JP6827357B2

JP6827357B2 - Solid oxide fuel cell system

Info

Publication number: JP6827357B2
Application number: JP2017074909A
Authority: JP
Inventors: 勝己檜垣; 雄也宅和
Original assignee: Osaka Gas Co Ltd
Current assignee: Osaka Gas Co Ltd
Priority date: 2017-04-05
Filing date: 2017-04-05
Publication date: 2021-02-10
Anticipated expiration: 2037-04-05
Also published as: JP2018181455A

Description

本発明は、燃料ガスを改質した改質燃料ガス及び酸化材ガスの酸化及び還元によって発電を行う固体酸化物形燃料電池システムに関する。 The present invention relates to a solid oxide fuel cell system that generates electricity by oxidizing and reducing a reformed fuel gas obtained by reforming a fuel gas and an oxide gas.

燃料電池システムとして、固体酸化物形の燃料電池セルを積層したセルスタックを備えた固体酸化物形燃料電池（ＳＯＦＣ）が実用に供されている（例えば、特許文献１参照）。この固体酸化物形の燃料電池セルは、酸素イオンを伝導する固体電解質の片側に改質燃料ガス（「燃料ガス」とも称する）を酸化する燃料極が配設され、その他側に酸化材ガス（例えば、空気中の酸素）を還元する酸素極が配設され、固体電解質の材料として、一般的にイットリアをドープしたジルコニアが用いられている。 As a fuel cell system, a solid oxide fuel cell (SOFC) provided with a cell stack in which solid oxide fuel cell cells are stacked is put into practical use (see, for example, Patent Document 1). In this solid oxide fuel cell, a fuel electrode that oxidizes reformed fuel gas (also referred to as "fuel gas") is arranged on one side of a solid electrolyte that conducts oxygen ions, and an oxide gas (also referred to as "fuel gas") is arranged on the other side. For example, an oxygen electrode for reducing oxygen in the air) is arranged, and zirconia doped with itria is generally used as a material for a solid electrolyte.

この固体酸化物形のセルスタックは、７００〜１０００℃の高温で、燃料ガス中の水素、一酸化炭素、炭化水素と酸化材ガス中の酸素とを電気化学反応させて発電が行われる。固体酸化物形燃料電池システムは、他の燃料電池システムやガスエンジンなどに比べて、特に高発電効率での発電が可能なことから、有望な発電技術として開発が行われてきた。 This solid oxide type cell stack generates electricity by electrochemically reacting hydrogen, carbon monoxide, and hydrocarbons in the fuel gas with oxygen in the oxide gas at a high temperature of 700 to 1000 ° C. The solid oxide fuel cell system has been developed as a promising power generation technology because it can generate power with particularly high power generation efficiency as compared with other fuel cell systems and gas engines.

固体酸化物形燃料電池システムはセルスタックの作動温度が高いため、セルスタックにて消費されない（発電に寄与しない）燃料ガス、換言するとセルスタックの燃料極側から流出する改質燃料ガス（反応燃料ガス）と、セルスタックの酸素極側から流出する酸化材ガス（空気）とが、セルスタックの排出側の燃焼空間において燃焼され、この燃焼によって得られる燃焼熱により、改質用水を気化する気化器や燃料ガスを水蒸気改質する改質器が加熱されるように構成されている。 Since the operating temperature of the cell stack is high in the solid oxide fuel cell system, the fuel gas that is not consumed in the cell stack (does not contribute to power generation), in other words, the reformed fuel gas that flows out from the fuel electrode side of the cell stack (reaction fuel). Gas) and oxide gas (air) flowing out from the oxygen electrode side of the cell stack are burned in the combustion space on the discharge side of the cell stack, and the combustion heat obtained by this combustion vaporizes the reforming water. It is configured to heat the vessel and the reformer that reforms the fuel gas with steam.

この公知の固体酸化物形燃料電池システムでは、この燃焼空間の上方に気化器及び改質器が配設されている。気化器で行われる気化反応及び改質器で行われる改質反応はともに吸熱反応であり、それ故に、燃焼空間の燃焼で生じる熱はこれらの吸熱反応により奪われ、熱が奪われた後の燃焼排気ガスが外部に排出される。 In this known solid oxide fuel cell system, a vaporizer and a reformer are arranged above the combustion space. Both the vaporization reaction performed in the vaporizer and the reforming reaction performed in the reformer are endothermic reactions, and therefore, the heat generated by combustion in the combustion space is deprived by these endothermic reactions, and after the heat is deprived. Combustion exhaust gas is discharged to the outside.

このような固体酸化物形燃料電池システムのセルスタックで消費される燃料ガス（即ち、発電に寄与する燃料ガス）の割合は燃料利用率で示される。正確には、燃料利用率は、燃料ガスの流量に比例する燃料ガスの価電子の供給速度に対し、発電による燃料価電子の消費速度の割合をいう。 The ratio of fuel gas (that is, fuel gas that contributes to power generation) consumed in the cell stack of such a solid oxide fuel cell system is indicated by the fuel utilization rate. To be precise, the fuel utilization rate refers to the ratio of the consumption rate of fuel valence electrons by power generation to the supply rate of valence electrons of fuel gas, which is proportional to the flow rate of fuel gas.

また、固体酸化物形燃料システムの発電効率は、一般的に、次式（１）、
発電効率＝係数×セルスタック電圧×燃料利用率×補機効率×インバータ効率
で表される。ここで係数とは、燃料ガスの価電子数や熱量によって決定される係数であり、補機効率とは、セルスタックから出力された直流電力と、この直流電力により作動される各種ブロア、ポンプなど燃料電池システム内部を駆動するために補機にて消費される直流損失分を差し引いた後の正味直流出力との比であり、またインバータ効率とは、正味直流出力から交流出力に変換する際の変換効率である。 In addition, the power generation efficiency of solid oxide fuel cells is generally determined by the following equation (1),
It is expressed as power generation efficiency = coefficient x cell stack voltage x fuel utilization rate x auxiliary equipment efficiency x inverter efficiency. Here, the coefficient is a coefficient determined by the number of valence electrons and the amount of heat of the fuel gas, and the auxiliary machine efficiency is the DC power output from the cell stack and various blowers, pumps, etc. operated by this DC power. It is the ratio to the net DC output after deducting the DC loss consumed by the auxiliary equipment to drive the inside of the fuel cell system, and the inverter efficiency is the conversion from the net DC output to the AC output. Conversion efficiency.

上述の発電効率の式（１）から理解されるように、セルスタック（燃料電池セル）の出力電圧が同じであれば、燃料利用率が高いほど発電効率は高くなることが判る。しかし、この燃料利用率を高めたときには、セルスタックでの発電に使用しない余剰燃料ガスが減じるために、この燃焼空間での燃焼熱が少なくなってセルスタックの温度が低下し、これにより、セルスタックの内部抵抗が増加してセルスタックの発電電圧の低下を招くようになる。そのため、燃料利用率を単純に上昇させてもセルスタックの発電効率は頭打ちになる。また、この燃料利用率を極端に高くすると、燃焼空間における燃焼が部分的に正常に維持できなくなり、大幅な温度の低下を招くことが起こるおそれがある。この場合、気化器における気化状態に大きな変化を生じさせることになり、Ｓ／Ｃ（水蒸気／炭素の比率）も不安定になり、その結果、固体酸化物形燃料電池システムの即時故障モードに入る可能性が高くなる。 As can be understood from the above-mentioned power generation efficiency equation (1), if the output voltage of the cell stack (fuel cell) is the same, it can be seen that the higher the fuel utilization rate, the higher the power generation efficiency. However, when this fuel utilization rate is increased, the excess fuel gas that is not used for power generation in the cell stack is reduced, so that the heat of combustion in this combustion space is reduced and the temperature of the cell stack is lowered, which causes the cell. The internal resistance of the stack increases, leading to a decrease in the generated voltage of the cell stack. Therefore, even if the fuel utilization rate is simply increased, the power generation efficiency of the cell stack will reach a plateau. Further, if the fuel utilization rate is extremely high, combustion in the combustion space cannot be partially maintained normally, which may lead to a significant decrease in temperature. In this case, the vaporization state in the vaporizer will change significantly, and the S / C (water vapor / carbon ratio) will also become unstable, resulting in an immediate failure mode of the solid oxide fuel cell system. The possibility is high.

一方、燃料利用率と並んで、固体酸化物形燃料電池システムを稼働させる際の重要な制御パラメーターとして酸化材利用率（酸化ガスが空気である場合、空気利用率）がある。この空気利用率とは、セルスタックに供給する酸素の総量に対する発電に利用される酸素の割合である。酸化材ガス（例えば、空気）の流量と空気利用率とは、セルスタックの動作温度を適正範囲に保つ上で最適な制御範囲が設定される。即ち、酸化材ガスの流量が少なければ、酸化材ガスによる冷却作用が低下してセルスタックの温度が上昇し、これにより、セルスタックの出力電圧は高くなり、高い発電効率を得るには有利となるが、セルスタックの耐熱性を考慮すると、所定の流量以下にすることはできない。また、セルスタックの経年劣化などによる温度上昇を相殺するためにセルスタックの冷却を行いたい場合、初期に設定された酸化材ガスの供給流量よりも増やして（即ち、空気利用率を低下させて）セルスタックの温度を適正範囲に収めることも行われる。 On the other hand, along with the fuel utilization rate, there is an oxide utilization rate (air utilization rate when the oxide gas is air) as an important control parameter when operating the solid oxide fuel cell system. This air utilization rate is the ratio of oxygen used for power generation to the total amount of oxygen supplied to the cell stack. The flow rate of the oxide gas (for example, air) and the air utilization rate are set to the optimum control range for keeping the operating temperature of the cell stack within an appropriate range. That is, if the flow rate of the oxide gas is small, the cooling action of the oxide gas decreases and the temperature of the cell stack rises, which increases the output voltage of the cell stack, which is advantageous for obtaining high power generation efficiency. However, considering the heat resistance of the cell stack, the flow rate cannot be reduced to a predetermined level or less. Further, when it is desired to cool the cell stack in order to offset the temperature rise due to the aging deterioration of the cell stack, increase the supply flow rate of the oxide gas (that is, reduce the air utilization rate) set at the initial setting. ) It is also done to keep the temperature of the cell stack within the proper range.

このような固体酸化物形燃料電池システムでは、その発電中においては、上述したことを考慮しながら燃料ガスの燃料利用率及び酸化材ガスの酸化材利用率（空気の場合、空気利用率）を設定し、設定した燃料利用率及び酸化材利用率となるように燃料ガス及び酸化材ガスの供給が制御される。 In such a solid oxide fuel cell system, during the power generation, the fuel utilization rate of the fuel gas and the oxide utilization rate of the oxide gas (in the case of air, the air utilization rate) are determined in consideration of the above. The supply of fuel gas and oxide gas is controlled so as to be set and the set fuel utilization rate and oxide utilization rate are obtained.

燃料ガス及び酸化材ガスの供給の制御の代表的方法の一つは、セルスタックの発電出力の電流値（出力値）に基づく方法であり、この方法では、発電出力の電流値が決定され、この電流値となるように燃料ガスの燃料利用率と酸化材ガス（例えば、空気）の酸化材利用率が決定され、この燃料利用率及び酸化材利用率となるように燃料ガスの流量及び酸化材ガスの流量が算出され、この算出された流量となるように、燃料ガスブロア及び酸化材ガスブロア（空気ブロア）が作動制御される。このような制御方法による運転は、燃料利用率及び酸化材利用率に基づき制御する利用率値優先運転となり、セルスタックの温度（作動温度）は、外気温度の変化、燃料ガス流量計測手段の検知誤差、更には、セルスタックの経年劣化によるジュール発熱の上昇などにより変動する。 One of the typical methods for controlling the supply of fuel gas and oxide gas is a method based on the current value (output value) of the power generation output of the cell stack, and in this method, the current value of the power generation output is determined. The fuel utilization rate of the fuel gas and the oxide utilization rate of the oxide gas (for example, air) are determined so as to have this current value, and the flow rate and oxidation of the fuel gas so as to be the fuel utilization rate and the oxide utilization rate. The flow rate of the material gas is calculated, and the operation of the fuel gas blower and the oxide gas blower (air blower) is controlled so as to obtain the calculated flow rate. The operation by such a control method becomes the utilization rate value priority operation controlled based on the fuel utilization rate and the oxide material utilization rate, and the cell stack temperature (operating temperature) is detected by the change in the outside air temperature and the fuel gas flow rate measuring means. It fluctuates due to an error and an increase in Joule heat generation due to aged deterioration of the cell stack.

この代表的方法の他の一つは、セルスタック又はその近傍の温度（所謂、作動温度）に基づく方法であり、この方法では、セルスタックの温度（作動温度）と例えば燃料ガスの燃料利用率が決定され、そして、この温度となるように酸化材ガス（例えば、空気）の酸化材利用率（例えば、空気利用率）が可変に設定され、セルスタックの温度が目標温度になるように燃料ガスブロア及び酸化材ガスブロア（空気ブロア）が作動制御される。このような制御方法による運転は、セルスタックの温度に基づき制御する温度優先運転となり、例えば、セルスタックの経年劣化などによる温度上昇を相殺するために酸化材ガス（例えば、空気）の供給流量を増大させて所望の温度範囲に収まるようにする制御は、この運転方法となる。 The other one of the typical methods is a method based on the temperature of the cell stack or its vicinity (so-called operating temperature), and in this method, the temperature of the cell stack (operating temperature) and the fuel utilization rate of, for example, fuel gas. Is determined, and the oxide utilization (eg, air utilization) of the oxide gas (eg, air) is variably set to this temperature, and the fuel so that the cell stack temperature reaches the target temperature. The operation of the gas blower and the oxide gas blower (air blower) is controlled. The operation by such a control method is a temperature priority operation in which the temperature is controlled based on the temperature of the cell stack. For example, the supply flow rate of the oxide gas (for example, air) is adjusted to offset the temperature rise due to the aging deterioration of the cell stack. Control to increase the temperature so that it falls within a desired temperature range is this method of operation.

特開２００６−１９０８４号公報Japanese Unexamined Patent Publication No. 2006-19804

この固体酸化物形燃料電池システムの運転において、燃料ガスの燃料利用率は、燃料ガスの価電子の供給速度に対し、発電による燃料価電子の消費速の割合であり、これは燃料電池システム上、セルスタックから引き出す電流値と、燃料電池システムが認識している燃料ガスの供給流量にて決定されるが、この燃料ガスの供給流量に関しては、それを計測する燃料ガス流量計測手段（例えば、燃料ガス流量計測センサ）の計測精度が問題となり、燃料ガスの供給流量については、燃料ガス流量計測手段の検知誤差により意図した供給流量になっていないことがある。この検知誤差、即ち実際の供給流量との乖離は、燃料電池システムの外部に設置した別個の流量計にて計測することが可能であるが、流量を計測する流量計測センサ（燃料ガス流量計測センサ、酸化材ガス流量計測センサ）については、一般的に計測値の±3％程度のものが使用されることが多く、燃料電池システムでは、この流量計測センサ（燃料ガス流量計測センサ、酸化材ガス流量計測センサ）の流量誤差を把握することは困難である。 In the operation of this solid oxide fuel cell system, the fuel utilization rate of the fuel gas is the ratio of the consumption rate of the fuel valence electrons by the power generation to the supply rate of the valence electrons of the fuel gas, which is on the fuel cell system. , The current value drawn from the cell stack and the fuel gas supply flow rate recognized by the fuel cell system are determined. The fuel gas supply flow rate is determined by a fuel gas flow rate measuring means (for example,) for measuring the fuel gas supply flow rate. The measurement accuracy of the fuel gas flow rate measuring sensor) becomes a problem, and the fuel gas supply flow rate may not be the intended supply flow rate due to a detection error of the fuel gas flow rate measuring means. This detection error, that is, the deviation from the actual supply flow rate, can be measured by a separate flow meter installed outside the fuel cell system, but a flow rate measurement sensor (fuel gas flow rate measurement sensor) that measures the flow rate. , Oxidate gas flow rate measurement sensor) is generally about ± 3% of the measured value, and in the fuel cell system, this flow rate measurement sensor (fuel gas flow rate measurement sensor, oxide gas) It is difficult to grasp the flow rate error of the flow rate measurement sensor).

このことを具体的に説明すると、固体酸化物形燃料電池システムに用いた燃料ガス流量計測センサの計測値に検知誤差が存在し、燃料ガス流量計測センサが実際の供給流量値よりも少ない値を示している（換言すると、マイナス側の検知誤差がある）場合、この燃料電池システムが認識している供給流量（即ち、燃料ガス流量計測センサの計測値）よりもより多くの燃料ガスが供給され、より多くの燃料ガスを流す方向の制御誤差が生じている。例えば、燃料電池システムが、上限の燃料利用率を例えば８０．５％に設定しているとしても、上述した燃料ガス流量計測センサのマイナス側の検知誤差により多くの燃料ガスを流す方向の制御誤差が生じ、この制御誤差により実際の燃料利用率は例えば７９％程度に止まり、燃料電池システムの発電効率自体が意図した目標レベルに到達しないことが起こり得る。 To explain this concretely, there is a detection error in the measured value of the fuel gas flow rate measurement sensor used in the solid oxide fuel cell system, and the fuel gas flow rate measurement sensor sets a value smaller than the actual supply flow rate value. When indicated (in other words, there is a detection error on the negative side), more fuel gas is supplied than the supply flow rate recognized by this fuel cell system (that is, the value measured by the fuel gas flow rate measurement sensor). , There is a control error in the direction in which more fuel gas flows. For example, even if the fuel cell system sets the upper limit fuel utilization rate to, for example, 80.5%, the control error in the direction in which more fuel gas flows due to the detection error on the negative side of the fuel gas flow rate measurement sensor described above. Due to this control error, the actual fuel utilization rate may be limited to, for example, about 79%, and the power generation efficiency of the fuel cell system itself may not reach the intended target level.

本発明の目的は、高い燃料利用率を設定する際に特に問題となる燃料ガスの供給流量の検知誤差の有無をセルスタックの発電中に確認することができる固体酸化物形燃料電池システムを提供することである。 An object of the present invention is to provide a solid oxide fuel cell system capable of confirming the presence or absence of a detection error of a fuel gas supply flow rate, which is a particular problem when setting a high fuel utilization rate, during power generation of a cell stack. It is to be.

本発明の請求項１に記載の固体酸化物形燃料電池システムは、燃料ガス及び酸化材ガスを反応させて発電を行う固体酸化物形の燃料電池セルを積層したセルスタックと、酸化材ガスを前記セルスタックの酸素極側に送給するための酸化材ガス供給手段と、燃料ガスを前記セルスタックの燃料極側に供給するための燃料ガス供給手段と、前記燃料ガス供給手段から前記セルスタックの前記燃料極側に供給される燃料ガスの流量を計測するための燃料ガス流量計測手段と、前記セルスタックの温度を検知するための温度検知手段と、前記燃料ガス供給手段及び前記酸化材ガス供給手段を作動制御するためのコントローラと、を備えた固体酸化物形燃料電池システムであって、
前記コントローラは、前記セルスタックでの発電で消費される燃料ガスの利用率を設定するための燃料利用率設定手段と、前記セルスタックでの発電で消費される酸化材ガスの利用率を設定するための酸化材利用率設定手段と、前記燃料ガス流量計測手段の検知誤差の有無を判定するための流量誤差判定手段とを含み、
前記セルスタックの定格発電状態において、前記コントローラは、燃料利用率及び酸化材利用率を優先した利用率値優先運転を行い、前記利用率値優先運転においては、前記燃料利用率設定手段は第１燃料利用率を設定するとともに、前記酸化材利用率設定手段は第１酸化材利用率を設定し、その後、前記コントローラは、燃料利用率を上昇させた利用率上昇運転を行い、前記利用率上昇運転においては、前記酸化材利用率設定手段は前記第１酸化材利用率を維持するとともに、前記燃料利用率設定手段は前記第１燃料利用率よりも高い第２燃料利用率を設定し、前記温度検知手段は、前記利用率値優先運転における前記セルスタックの第１温度状態と前記利用率上昇運転における前記セルスタックの第２温度状態を検知し、前記流量誤差判定手段は、前記セルスタックの前記第１温度状態における第１検知温度及び前記第２温度状態における第２検知温度に基づいて前記燃料ガス流量計測手段の検知誤差の有無を判定することを特徴とする。 The solid oxide fuel cell system according to claim 1 of the present invention comprises a cell stack in which solid oxide fuel cell cells that generate power by reacting a fuel gas and an oxide gas are laminated, and an oxide gas. An oxide gas supply means for supplying to the oxygen electrode side of the cell stack, a fuel gas supply means for supplying fuel gas to the fuel electrode side of the cell stack, and the cell stack from the fuel gas supply means. A fuel gas flow rate measuring means for measuring the flow rate of the fuel gas supplied to the fuel electrode side, a temperature detecting means for detecting the temperature of the cell stack, the fuel gas supply means, and the oxide gas. A solid oxide fuel cell system equipped with a controller for operating and controlling the supply means.
The controller sets the fuel utilization rate setting means for setting the utilization rate of the fuel gas consumed in the power generation in the cell stack, and the utilization rate of the oxide gas consumed in the power generation in the cell stack. The oxide material utilization rate setting means for the purpose and the flow rate error determining means for determining the presence or absence of the detection error of the fuel gas flow rate measuring means are included.
In the rated power generation state of the cell stack, the controller performs a utilization rate value priority operation that prioritizes the fuel utilization rate and the oxide material utilization rate, and in the utilization rate value priority operation, the fuel utilization rate setting means is the first. While setting the fuel utilization rate, the oxide utilization rate setting means sets the first oxide utilization rate, and then the controller performs a utilization rate increase operation in which the fuel utilization rate is increased, and the utilization rate is increased. In operation, the oxide utilization rate setting means maintains the first oxide utilization rate, and the fuel utilization rate setting means sets a second fuel utilization rate higher than the first fuel utilization rate. The temperature detecting means detects the first temperature state of the cell stack in the utilization rate value priority operation and the second temperature state of the cell stack in the utilization rate increasing operation, and the flow rate error determining means of the cell stack It is characterized in that the presence or absence of a detection error of the fuel gas flow rate measuring means is determined based on the first detection temperature in the first temperature state and the second detection temperature in the second temperature state.

また、本発明の請求項２に記載の固体酸化物形燃料電池システムでは、前記流量誤差判定手段は、前記温度検知手段の前記第１検知温度及び前記第２検知温度の演算温度差と基準温度差とを比較し、前記演算温度差が前記基準温度差よりも小さいときに前記燃料ガス流量計測手段にプラス側誤差ありの判定を行い、前記燃料利用率設定手段は、前記第２燃料利用率よりも高い第３燃料利用率を設定することを特徴とする。 Further, in the solid oxide fuel cell system according to claim 2 of the present invention, the flow rate error determining means is the calculated temperature difference between the first detected temperature and the second detected temperature of the temperature detecting means and the reference temperature. The difference is compared, and when the calculated temperature difference is smaller than the reference temperature difference, it is determined that the fuel gas flow rate measuring means has a positive side error, and the fuel utilization rate setting means determines the second fuel utilization rate. It is characterized by setting a higher third fuel utilization rate.

また、本発明の請求項３に記載の固体酸化物形燃料電池システムでは、前記コントローラは、前記流量誤差判定手段が前記燃料ガス流量計測手段にプラス側誤差ありとの判定したときに前記第２燃料利用率から更に上昇させる上昇利用率を演算するための上昇利用率演算手段を含み、前記上昇利用率演算手段は、前記演算温度差と前記基準温度差との比較温度差に基づいて前記上昇利用率を演算し、前記燃料利用率設定手段は、前記第２燃料利用率に前記上昇利用率を加算した前記第３燃料利用率を設定することを特徴とする。 Further, in the solid oxide fuel cell system according to claim 3 of the present invention, the controller determines that the fuel gas flow rate measuring means has a positive side error when the flow rate error determining means determines that the fuel gas flow rate measuring means has a positive side error. The increase utilization rate calculation means for calculating the increase utilization rate to be further increased from the fuel utilization rate is included, and the increase utilization rate calculation means is said to increase based on a comparative temperature difference between the calculated temperature difference and the reference temperature difference. The fuel utilization rate setting means calculates the utilization rate, and is characterized in that the third fuel utilization rate is set by adding the increase utilization rate to the second fuel utilization rate.

また、本発明の請求項４に記載の固体酸化物形燃料電池システムは、燃料ガス及び酸化材ガスを反応させて発電を行う固体酸化物形の燃料電池セルを積層したセルスタックと、酸化材ガスを前記セルスタックの酸素極側に送給するための酸化材ガス供給手段と、燃料ガスを前記セルスタックの燃料極側に供給するための燃料ガス供給手段と、前記燃料ガス供給手段から前記セルスタックの前記燃料極側に供給される燃料ガスの流量を計測するための燃料ガス流量計測手段と、前記酸化材ガス供給手段から前記セルスタックの前記酸素極側に供給される酸化材ガスの流量を計測するための酸化材ガス流量計測手段と、前記セルスタックの温度を検知するための温度検知手段と、前記燃料ガス供給手段及び前記酸化材ガス供給手段を作動制御するためのコントローラと、を備えた固体酸化物形燃料電池システムであって、
前記コントローラは、前記セルスタックでの発電で消費される燃料ガスの利用率を設定するための燃料利用率設定手段と、前記セルスタックでの発電で消費される酸化材ガスの利用率を設定するための酸化材利用率設定手段と、前記燃料ガス流量計測手段の検知誤差の有無を判定するための流量誤差判定手段とを含み、
前記セルスタックの定格発電状態において、前記コントローラは、燃料利用率及び酸化材利用率を優先した利用率値優先運転を行い、前記利用率値優先運転においては、前記燃料利用率設定手段は第１燃料利用率を設定するとともに、前記酸化材利用率設定手段は第１酸化材利用率を設定し、その後、前記コントローラは、前記温度検知手段の検知温度が目標温度となるように温度優先運転を行い、前記温度優先運転においては、前記燃料利用率設定手段は前記第１燃料利用率よりも高い第２燃料利用率を設定するとともに、前記酸化材ガス供給手段は、前記温度検知手段の検知温度が前記目標温度となるように制御され、その後、前記流量誤差判定手段は、前記温度優先運転における第２酸化材利用率に基づいて前記燃料ガス流量計測手段の検知誤差の有無を判定することを特徴とする。 Further, the solid oxide fuel cell system according to claim 4 of the present invention has a cell stack in which solid oxide fuel cell cells for generating power by reacting a fuel gas and an oxide gas to generate electricity, and an oxide material. From the oxide gas supply means for supplying gas to the oxygen electrode side of the cell stack, the fuel gas supply means for supplying fuel gas to the fuel electrode side of the cell stack, and the fuel gas supply means. A fuel gas flow rate measuring means for measuring the flow rate of the fuel gas supplied to the fuel electrode side of the cell stack, and an oxide gas supplied from the oxide gas supply means to the oxygen electrode side of the cell stack. An oxide gas flow rate measuring means for measuring the flow rate, a temperature detecting means for detecting the temperature of the cell stack, a controller for operating and controlling the fuel gas supply means and the oxide gas supply means, and the like. It is a solid oxide fuel cell system equipped with
The controller sets the fuel utilization rate setting means for setting the utilization rate of the fuel gas consumed in the power generation in the cell stack, and the utilization rate of the oxide gas consumed in the power generation in the cell stack. The oxide material utilization rate setting means for the purpose and the flow rate error determining means for determining the presence or absence of the detection error of the fuel gas flow rate measuring means are included.
In the rated power generation state of the cell stack, the controller performs a utilization rate value priority operation that prioritizes the fuel utilization rate and the oxide material utilization rate, and in the utilization rate value priority operation, the fuel utilization rate setting means is the first. While setting the fuel utilization rate, the oxide utilization rate setting means sets the first oxide utilization rate, and then the controller performs a temperature priority operation so that the detection temperature of the temperature detection means becomes the target temperature. In the temperature priority operation, the fuel utilization rate setting means sets a second fuel utilization rate higher than the first fuel utilization rate, and the oxide gas supply means sets the detection temperature of the temperature detection means. Is controlled to be the target temperature, and then the flow error determining means determines whether or not there is a detection error of the fuel gas flow measuring means based on the second oxide utilization rate in the temperature priority operation. It is a feature.

また、本発明の請求項５に記載の固体酸化物形燃料電池システムでは、前記コントローラは、酸化材利用率を演算するための酸化材利用率演算手段を含み、前記酸化材利用率演算手段は、前記温度優先運転における酸化材ガスの供給流量に基づいて前記第２酸化材利用率を演算し、前記流量誤差判定手段は、前記温度優先運転における前記第２酸化材利用率と基準酸化材利用率とを比較し、前記第２酸化材利用率が前記基準酸化材利用率よりも小さいときに前記燃料ガス流量計測手段にプラス側誤差ありの判定を行い、前記燃料利用率設定手段は、前記第２燃料利用率よりも高い第３燃料利用率を設定することを特徴とする。 Further, in the solid oxide fuel cell system according to claim 5 of the present invention, the controller includes an oxide material utilization rate calculation means for calculating the oxide material utilization rate, and the oxide material utilization rate calculation means is The second oxide utilization rate is calculated based on the supply flow rate of the oxide gas in the temperature priority operation, and the flow error determination means uses the second oxide utilization rate and the reference oxide utilization in the temperature priority operation. The rate is compared, and when the second oxide utilization rate is smaller than the reference oxide utilization rate, it is determined that the fuel gas flow rate measuring means has a positive side error, and the fuel utilization rate setting means is described. It is characterized in that a third fuel utilization rate higher than the second fuel utilization rate is set.

また、本発明の請求項６に記載の固体酸化物形燃料電池システムでは、前記コントローラは、前記流量誤差判定手段がプラス側誤差ありとの判定したときに前記第２燃料利用率から更に上昇させる上昇利用率を演算するための上昇利用率演算手段を含み、前記上昇利用率演算手段は、前記第２酸化材利用率と前記基準酸化材利用率との比較酸化材利用率差に基づき前記上昇利用率を演算し、前記燃料利用率設定手段は、前記第２燃料利用率に前記上昇利用率を加算した前記第３燃料利用率に設定することを特徴とする。 Further, in the solid oxide fuel cell system according to claim 6 of the present invention, the controller further increases the fuel utilization rate from the second fuel when the flow error determining means determines that there is a positive side error. The increase utilization rate calculation means includes the increase utilization rate calculation means for calculating the increase utilization rate, and the increase utilization rate calculation means is based on the difference in the comparative oxide utilization rate between the second oxide material utilization rate and the reference oxide utilization rate. The utilization rate is calculated, and the fuel utilization rate setting means is set to the third fuel utilization rate by adding the increase utilization rate to the second fuel utilization rate.

また、本発明の請求項７に記載の固体酸化物形燃料電池システムは、燃料ガス及び酸化材ガスを反応させて発電を行う固体酸化物形の燃料電池セルを積層したセルスタックと、酸化材ガスを前記セルスタックの酸素極側に送給するための酸化材ガス供給手段と、燃料ガスを前記セルスタックの燃料極側に供給するための燃料ガス供給手段と、前記燃料ガス供給手段から前記セルスタックの前記燃料極側に供給される燃料ガスの流量を計測するための燃料ガス流量計測手段と、前記酸化材ガス供給手段から前記セルスタックの前記酸素極側に供給される酸化材ガスの流量を計測するための酸化材ガス流量計測手段と、前記セルスタックの温度を検知するための温度検知手段と、前記燃料ガス供給手段及び前記酸化材ガス供給手段を作動制御するためのコントローラと、を備えた固体酸化物形燃料電池システムであって、
前記コントローラは、前記セルスタックでの発電で消費される燃料ガスの利用率を設定するための燃料利用率設定手段と、前記セルスタックでの発電で消費される酸化材ガスの利用率を設定するための酸化材利用率設定手段と、前記燃料ガス流量計測手段の検知誤差の有無を判定するための流量誤差判定手段とを含み、
前記セルスタックの定格発電状態において、前記コントローラは、燃料利用率及び酸化材利用率を優先した利用率値優先運転を行い、前記利用率値優先運転においては、前記燃料利用率設定手段は第１燃料利用率を設定するとともに、前記酸化材利用率設定手段は第１酸化材利用率を設定し、その後、前記コントローラは、前記温度検知手段の検知温度が目標温度となるように第１温度優先運転を行い、前記第１温度優先運転においては、前記燃料利用率設定手段は前記第１燃料利用率を設定するとともに、前記酸化材ガス供給手段は、前記温度検知手段の検知温度が前記目標温度となるように制御され、更にその後、前記コントローラは第２温度優先運転を行い、前記第２温度優先運転においては、前記燃料利用率設定手段は前記第１燃料利用率よりも高い第２燃料利用率を設定するとともに、前記酸化材ガス供給手段は、前記温度検知手段の検知温度が前記目標温度となるように制御され、前記流量誤差判定手段は、前記第１温度優先運転における第２酸化材利用率及び前記第２温度優先運転における第３酸化材利用率に基づいて前記燃料ガス流量計測手段の検知誤差の有無を判定することを特徴とする。 Further, the solid oxide fuel cell system according to claim 7 of the present invention has a cell stack in which solid oxide fuel cell cells for generating power by reacting a fuel gas and an oxide gas to generate electricity, and an oxide material. From the oxide gas supply means for supplying gas to the oxygen electrode side of the cell stack, the fuel gas supply means for supplying fuel gas to the fuel electrode side of the cell stack, and the fuel gas supply means. A fuel gas flow rate measuring means for measuring the flow rate of the fuel gas supplied to the fuel electrode side of the cell stack, and an oxide gas supplied from the oxide gas supply means to the oxygen electrode side of the cell stack. An oxide gas flow rate measuring means for measuring the flow rate, a temperature detecting means for detecting the temperature of the cell stack, a controller for operating and controlling the fuel gas supply means and the oxide gas supply means, and the like. It is a solid oxide fuel cell system equipped with
The controller sets the fuel utilization rate setting means for setting the utilization rate of the fuel gas consumed in the power generation in the cell stack, and the utilization rate of the oxide gas consumed in the power generation in the cell stack. The oxide material utilization rate setting means for the purpose and the flow rate error determining means for determining the presence or absence of the detection error of the fuel gas flow rate measuring means are included.
In the rated power generation state of the cell stack, the controller performs a utilization rate value priority operation that prioritizes the fuel utilization rate and the oxide material utilization rate, and in the utilization rate value priority operation, the fuel utilization rate setting means is the first. While setting the fuel utilization rate, the oxide utilization rate setting means sets the first oxide utilization rate, and then the controller gives priority to the first temperature so that the detection temperature of the temperature detection means becomes the target temperature. In the first temperature priority operation, the fuel utilization rate setting means sets the first fuel utilization rate, and the oxide gas supply means sets the detection temperature of the temperature detecting means to the target temperature. After that, the controller performs a second temperature priority operation, and in the second temperature priority operation, the fuel utilization rate setting means uses a second fuel higher than the first fuel utilization rate. While setting the rate, the oxide gas supply means is controlled so that the detection temperature of the temperature detection means becomes the target temperature, and the flow error determination means is the second oxide material in the first temperature priority operation. It is characterized in that the presence or absence of a detection error of the fuel gas flow rate measuring means is determined based on the utilization rate and the utilization rate of the third oxide material in the second temperature priority operation.

また、本発明の請求項８に記載の固体酸化物形燃料電池システムでは、前記コントローラは、酸化材利用率を演算するための酸化材利用率演算手段を含み、前記酸化材利用率演算手段は、前記第１温度優先運転における酸化材ガスの供給流量に基づいて前記第２酸化材利用率を演算するとともに、前記第２温度優先運転における酸化材ガスの供給流量に基づいて前記第３酸化材利用率を演算し、前記流量誤差判定手段は、前記第２酸化材利用率及び前記第３酸化材利用率の演算酸化材利用率差と基準酸化材利用率差とを比較し、前記演算酸化材利用率差が前記基準酸化材利用率差よりも小さいときに前記燃料ガス流量計測手段にプラス側誤差ありの判定を行い、前記燃料利用率設定手段は、前記第２燃料利用率よりも高い第３燃料利用率を設定することを特徴とする。 Further, in the solid oxide fuel cell system according to claim 8 of the present invention, the controller includes an oxide material utilization rate calculation means for calculating the oxide material utilization rate, and the oxide material utilization rate calculation means is The second oxide utilization rate is calculated based on the supply flow rate of the oxide gas in the first temperature priority operation, and the third oxide gas is calculated based on the supply flow rate of the oxide gas in the second temperature priority operation. The utilization rate is calculated, and the flow error determination means compares the difference between the calculated second oxide utilization rate and the third oxide utilization rate with the reference oxide utilization rate difference, and the calculated oxidation When the material utilization rate difference is smaller than the reference oxide utilization rate difference, it is determined that the fuel gas flow rate measuring means has a positive side error, and the fuel utilization rate setting means is higher than the second fuel utilization rate. It is characterized by setting a third fuel utilization rate.

更に、本発明の請求項９に記載の固体酸化物形燃料電池システムでは、前記コントローラは、前記流量誤差判定手段が前記燃料ガス流量計測手段にプラス側誤差ありとの判定したときに前記第２燃料利用率から更に上昇させる上昇利用率を演算するための上昇利用率演算手段を含み、前記上昇利用率演算手段は、前記演算酸化材利用率差と前記基準酸化材利用率差との比較酸化材利用率差に基づいて前記上昇利用率を演算し、前記燃料利用率設定手段は、前記第２燃料利用率に前記上昇利用率を加算した前記第３燃料利用率を設定することを特徴とする。 Further, in the solid oxide fuel cell system according to claim 9 of the present invention, the controller determines that the fuel gas flow rate measuring means has a positive side error when the flow rate error determining means determines that the fuel gas flow rate measuring means has a positive side error. The increase utilization rate calculation means for calculating the increase utilization rate further increased from the fuel utilization rate is included, and the increase utilization rate calculation means is a comparative oxidation of the calculated oxide utilization rate difference and the reference oxide utilization rate difference. The increase utilization rate is calculated based on the material utilization rate difference, and the fuel utilization rate setting means sets the third fuel utilization rate by adding the increase utilization rate to the second fuel utilization rate. To do.

本発明の請求項１に記載の固体酸化物形燃料電池システムによれば、燃料電池システムを制御するためのコントローラは、燃料ガスの利用率を設定するための燃料利用率設定手段と、酸化材ガス（例えば、空気）の利用率を設定するための酸化材利用率設定手段（例えば、空気利用率設定手段）と、燃料ガス流量計測手段の検知誤差の有無を判定するための流量誤差判定手段とを含み、セルスタックの定格発電状態において、燃料利用率及び酸化材利用率を優先した利用率値優先運転が行なわれ、この利用率値優先運転においては、第１燃料利用率（例えば、７８％）及び第１酸化材利用率（例えば、３８％）が設定され、その後、燃料利用率を上昇させる利用率上昇運転が行われ、この利用率上昇運転においては、第１酸化材利用率（３８％）が維持された状態において第２燃料利用率（例えば、８０％）が設定される。このように運転状態を切り替えるときに、酸化材利用率（空気利用率）を一定に保持することにより、セルスタックの温度状態に着目してその変化状態を捉まえることができ、この温度状態の変化を利用して燃料ガス流量計測手段の検知誤差の有無を調べることができる。 According to the solid oxide fuel cell system according to claim 1 of the present invention, the controller for controlling the fuel cell system includes a fuel utilization rate setting means for setting a fuel gas utilization rate and an oxide material. Oxide material utilization rate setting means (for example, air utilization rate setting means) for setting the gas (for example, air) utilization rate, and flow rate error determining means for determining the presence or absence of a detection error of the fuel gas flow rate measuring means. In the rated power generation state of the cell stack, the utilization rate value priority operation that prioritizes the fuel utilization rate and the oxide material utilization rate is performed, and in this utilization rate value priority operation, the first fuel utilization rate (for example, 78) is performed. %) And the primary oxide utilization rate (for example, 38%) are set, and then a utilization rate increase operation for increasing the fuel utilization rate is performed. In this utilization rate increase operation, the primary oxide utilization rate (for example, 38%) is set. The second fuel utilization rate (for example, 80%) is set while the 38%) is maintained. By keeping the oxide material utilization rate (air utilization rate) constant when switching the operation state in this way, it is possible to focus on the temperature state of the cell stack and grasp the change state, and this temperature state can be grasped. The change can be used to check for detection errors in the fuel gas flow rate measuring means.

例えば、燃料ガス流量計測手段が実際の供給流量値よりも少ない値を示していて、燃料ガス流量計測手段にマイナス側の誤差がある場合、燃料ガスを実際の計測値よりも多く流す方向の制御誤差が生じ、この制御誤差がない場合に比してセルスタックの温度が高くなり、この温度状態の程度を見ることにより測定誤差の程度を知ることができる。 For example, if the fuel gas flow rate measuring means shows a value smaller than the actual supply flow rate value and the fuel gas flow rate measuring means has a negative error, control of the direction in which the fuel gas flows more than the actual measured value. An error occurs, and the temperature of the cell stack becomes higher than when there is no control error, and the degree of measurement error can be known by observing the degree of this temperature state.

また、本発明の請求項２に記載の固体酸化物形燃料電池システムによれば、温度検知手段の第１検知温度及び第２検知温度の演算温度差と基準温度差が比較され、この演算温度差が基準温度差よりも小さいと、流量誤差判定手段は、第１燃料利用率から第２燃料利用率に遷移する過程で燃料ガス流量計測手段にプラス側の検知誤差が拡大しているとの判定を行うようになる。そして、プラス側の検知誤差が拡大している場合、燃料ガスが計測流量値よりも多く供給されているために、燃料ガスの燃料利用率として第２燃料利用率よりも高い第３燃料利用率の設定が可能となり、この第３燃料利用率に設定することにより燃料電池システムの発電効率を高めることができる。 Further, according to the solid oxide fuel cell system according to claim 2 of the present invention, the calculated temperature difference between the first detection temperature and the second detection temperature of the temperature detecting means and the reference temperature difference are compared, and this calculated temperature is compared. If the difference is smaller than the reference temperature difference, the flow error determining means has an increased detection error on the positive side of the fuel gas flow measuring means in the process of transitioning from the first fuel utilization rate to the second fuel utilization rate. Judgment will be made. When the detection error on the plus side is widening, the fuel gas is supplied in a larger amount than the measured flow rate value, so that the fuel utilization rate of the fuel gas is higher than the second fuel utilization rate. Can be set, and the power generation efficiency of the fuel cell system can be improved by setting this third fuel utilization rate.

また、本発明の請求項３に記載の固体酸化物形燃料電池システムによれば、上昇利用率演算手段は、上述の演算温度差と基準温度差との比較温度差に基づいて上昇利用率を演算し、燃料利用率設定手段は、第２燃料利用率にこの上昇利用率を加算した第３燃料利用率を燃料利用率として設定するので、この第３燃料利用率は燃料ガス流量計測手段の検知誤差の程度に応じた値とすることができる。 Further, according to the solid oxide fuel cell system according to claim 3 of the present invention, the ascending utilization rate calculation means determines the ascending utilization rate based on the comparative temperature difference between the above-mentioned calculated temperature difference and the reference temperature difference. The fuel utilization rate setting means calculates and sets the third fuel utilization rate, which is the sum of the second fuel utilization rate and the increased utilization rate, as the fuel utilization rate. Therefore, the third fuel utilization rate is the fuel gas flow rate measuring means. The value can be set according to the degree of detection error.

また、本発明の請求項４に記載の固体酸化物形燃料電池システムによれば、燃料電池システムを制御するためのコントローラは、燃料ガスの利用率を設定するための燃料利用率設定手段と、酸化材ガス（例えば、空気）の利用率を設定するための酸化材利用率設定手段（例えば、空気利用率設定手段）と、燃料ガス流量計測手段の検知誤差の有無を判定するための流量誤差判定手段とを含み、セルスタックの定格発電状態において、燃料利用率及び酸化材利用率（例えば、空気利用率）を優先した利用率値優先運転を行い、この利用率値優先運転においては、第１燃料利用率（例えば、７８％）及び第１酸化材利用率（例えば、３８％）が設定され、その後、セルスタックの温度を目標温度に維持する温度優先運転が行なわれ、この温度優先運転においては、第１燃料利用率（例えば、７８％）よりも高い第２燃料利用率（例えば、８０％）が設定されるとともに、温度検知手段の検知温度が目標温度（例えば、７４３℃）となるように酸化材ガス供給手段が制御される。このように運転を切り替えるときに、温度優先運転における酸化材利用率に着目し、この温度優先運転における第２酸化材利用率を捉まえることにより、この第２空気利用率を利用して燃料ガス流量計測手段の検知誤差の有無を調べることができる。 Further, according to the solid oxide fuel cell system according to claim 4 of the present invention, the controller for controlling the fuel cell system includes a fuel utilization rate setting means for setting a fuel gas utilization rate and a fuel utilization rate setting means for setting the fuel gas utilization rate. Flow rate error for determining whether or not there is a detection error between the oxide material utilization rate setting means (for example, air utilization rate setting means) for setting the utilization rate of the oxide gas (for example, air) and the fuel gas flow rate measuring means. Including the determination means, in the rated power generation state of the cell stack, the utilization rate value priority operation that gives priority to the fuel utilization rate and the oxide material utilization rate (for example, the air utilization rate) is performed, and in this utilization rate value priority operation, the first 1 Fuel utilization rate (for example, 78%) and first oxide utilization rate (for example, 38%) are set, and then a temperature priority operation for maintaining the cell stack temperature at the target temperature is performed, and this temperature priority operation is performed. In, a second fuel utilization rate (for example, 80%) higher than the first fuel utilization rate (for example, 78%) is set, and the detection temperature of the temperature detecting means is set to the target temperature (for example, 743 ° C.). The oxide gas supply means is controlled so as to be. When switching the operation in this way, paying attention to the oxide material utilization rate in the temperature priority operation and grasping the second oxide material utilization rate in this temperature priority operation, the fuel gas is utilized by utilizing this second air utilization rate. It is possible to check the presence or absence of a detection error of the flow rate measuring means.

例えば、燃料ガス流量計測手段が実際の供給流量値よりも少ない値を示していて、燃料ガスの計測流量にマイナス側の検知誤差がある場合、より多くの燃料ガスを流す制御誤差を生じるようになり、その結果、セルスタックの温度が上昇傾向となり、目標温度に保つために酸化材ガスの供給量が増加し（このことは、酸化材利用率が小さくなることを意味する）、この酸化材利用率の低下を見ることにより測定誤差の程度を知ることができる。 For example, if the fuel gas flow rate measuring means shows a value smaller than the actual supply flow rate value and the measured flow rate of the fuel gas has a detection error on the negative side, a control error for flowing more fuel gas may occur. As a result, the temperature of the cell stack tends to rise, and the amount of oxide gas supplied to maintain the target temperature increases (this means that the oxide utilization rate decreases), and this oxide material is used. The degree of measurement error can be known by observing the decrease in utilization rate.

また、本発明の請求項５に記載の固体酸化物形燃料電池システムによれば、酸化材利用率演算手段は、温度優先運転における酸化材ガスの流量に基づいて第２酸化材利用率を演算し、この温度優先運転における第２酸化材利用率（第２空気利用率）と基準酸化材利用率（基準空気材利用率）との比較が行われ、第２酸化材利用率と基準酸化材利用率とが等しいときには検知誤差はないが、この第２酸化材利用率が基準酸化材利用率よりも小さいと、燃料ガスが計測流量よりも多く供給されているとして、流量誤差判定手段は燃料ガス流量計測手段にプラス側誤差ありとの判定を行い、この判定に基づき、第２燃料利用率よりも高い第３燃料利用率が設定される。 Further, according to the solid oxide fuel cell system according to claim 5 of the present invention, the oxide material utilization rate calculation means calculates the second oxide material utilization rate based on the flow rate of the oxide material gas in the temperature priority operation. Then, the second oxide utilization rate (second air utilization rate) and the reference oxide utilization rate (reference air material utilization rate) in this temperature priority operation are compared, and the second oxide utilization rate and the reference oxide utilization material are compared. When the utilization rate is equal, there is no detection error, but when this second oxide utilization rate is smaller than the reference oxide utilization rate, it is assumed that more fuel gas is supplied than the measured flow rate, and the flow error determination means is fuel. It is determined that the gas flow rate measuring means has a positive side error, and based on this determination, a third fuel utilization rate higher than the second fuel utilization rate is set.

また、本発明の請求項６に記載の固体酸化物形燃料電池システムによれば、上昇利用率演算手段は、上述の第２酸化材利用率（例えば、第２空気利用率）と基準酸化材利用率（例えば、基準空気利用率）との酸化材利用率差に基づいて上昇利用率を演算し、燃料利用率設定手段は、第２燃料利用率にこの上昇利用率を加算した第３燃料利用率を燃料利用率として設定するので、このようにしても第３燃料利用率を燃料ガス流量計測手段の検知誤差の程度に応じた値とすることができる。 Further, according to the solid oxide fuel cell system according to claim 6 of the present invention, the rising utilization rate calculation means is the above-mentioned second oxide utilization rate (for example, second air utilization rate) and the reference oxide material. The increase utilization rate is calculated based on the difference in the oxide utilization rate from the utilization rate (for example, the reference air utilization rate), and the fuel utilization rate setting means is the third fuel obtained by adding this increase utilization rate to the second fuel utilization rate. Since the utilization rate is set as the fuel utilization rate, the third fuel utilization rate can be set to a value according to the degree of the detection error of the fuel gas flow rate measuring means.

また、本発明の請求項７に記載の固体酸化物形燃料電池システムによれば、燃料電池システムを制御するためのコントローラは、燃料ガスの利用率を設定するための燃料利用率設定手段と、酸化材ガス（例えば、空気）の利用率を設定するための酸化材利用率設定手段（例えば、空気利用率設定手段）と、燃料ガス流量計測手段の検知誤差の有無を判定するための流量誤差判定手段とを含み、セルスタックの定格発電状態において、燃料利用率及び酸化材利用率を優先した利用率値優先運転を行い、この利用率値優先運転においては、第１燃料利用率（例えば、７８％）及び第１酸化材利用率（例えば、３８％）が設定され、その後、セルスタックの温度が目標温度となるように第１温度優先運転を行い、この第１温度優先運転においては、第１燃料利用率（例えば、７８％）に維持した状態においてセルスタックの温度が目標温度（例えば、７４３℃）となるように酸化材ガス供給手段が制御され、更にその後、第２温度優先運転において、第１燃料利用率（例えば、７８％）よりも高い第２燃料利用率（例えば、８０％）が設定されるとともに、セルスタックの温度がこの目標温度（例えば、７４３℃）となるように酸化材ガス供給手段が制御される。このように運転を切り替えるときに、第１温度優先運転における第２酸化材利用率と第２温度優先運転における第３酸化材利用率との酸化材利用率の変動に着目し、この酸化材利用率の変化状態を捉まえることにより、燃料ガス流量計測手段の検知誤差の有無を調べることができる。 Further, according to the solid oxide fuel cell system according to claim 7 of the present invention, the controller for controlling the fuel cell system includes a fuel utilization rate setting means for setting the fuel gas utilization rate and a fuel utilization rate setting means for setting the fuel gas utilization rate. Flow rate error for determining whether or not there is a detection error between the oxide material utilization rate setting means (for example, air utilization rate setting means) for setting the utilization rate of the oxide material gas (for example, air) and the fuel gas flow rate measuring means. Including the determination means, the fuel utilization rate and the oxide material utilization rate are prioritized in the utilization rate value priority operation in the rated power generation state of the cell stack, and in this utilization rate value priority operation, the first fuel utilization rate (for example, 78%) and the first oxide utilization rate (for example, 38%) are set, and then the first temperature priority operation is performed so that the temperature of the cell stack becomes the target temperature, and in this first temperature priority operation, The oxide gas supply means is controlled so that the temperature of the cell stack reaches the target temperature (for example, 743 ° C.) while the first fuel utilization rate (for example, 78%) is maintained, and then the second temperature priority operation is performed. In, a second fuel utilization rate (for example, 80%) higher than the first fuel utilization rate (for example, 78%) is set, and the temperature of the cell stack becomes this target temperature (for example, 743 ° C.). The oxide gas supply means is controlled. When switching the operations in this way, paying attention to the fluctuation of the oxide utilization rate between the second oxide utilization rate in the first temperature priority operation and the third oxide utilization rate in the second temperature priority operation, this oxide utilization By capturing the change state of the rate, it is possible to check the presence or absence of a detection error of the fuel gas flow rate measuring means.

また、本発明の請求項８に記載の固体酸化物形燃料電池システムによれば、酸化材利用率演算手段は、第１温度優先運転における酸化材ガスの流量に基づいて第２酸化材利用率を演算し、また第２温度優先運転における酸化材ガスの流量に基づいて第３酸化利用率を演算する。そして、流量誤差判定手段は、第２酸化材利用率及び第３酸化材利用率の演算酸化材利用率差と基準酸化材利用率差とを比較し、この演算酸化材利用率差が基準酸化材利用率差よりも小さいときに、燃料ガスが計測流量値より多く供給されているとして流量誤差判定手段は燃料ガス流量計測手段にプラス側誤差ありとの判定を行い、第２燃料利用率よりも高い第３燃料利用率が設定される。 Further, according to the solid oxide fuel cell system according to claim 8 of the present invention, the oxide material utilization rate calculation means uses the second oxide material utilization rate based on the flow rate of the oxide material gas in the first temperature priority operation. Is calculated, and the third oxidation utilization rate is calculated based on the flow rate of the oxide gas in the second temperature priority operation. Then, the flow rate error determining means compares the calculated difference in the utilization rate of the second oxide material and the third utilization rate of the third oxide material with the difference in the utilization rate of the reference oxide material, and the difference in the utilization rate of the reference oxide material is the reference oxidation. When it is smaller than the material utilization rate difference, the flow rate error determining means determines that the fuel gas flow rate measuring means has a positive side error, assuming that more fuel gas is supplied than the measured flow rate value, and the second fuel utilization rate is used. A high third fuel utilization rate is set.

更に、本発明の請求項９に記載の固体酸化物形燃料電池システムによれば、上昇利用率演算手段は、上述の演算酸化材利用率差と基準酸化材利用率差との比較酸化材利用率差に基づいて上昇利用率を演算し、燃料利用率設定手段は、第２燃料利用率にこの上昇利用率を加算した前記第３燃料利用率を設定するで、この第３燃料利用率は、燃料ガス流量計測手段の検知誤差の程度に応じた値とすることができる。 Further, according to the solid oxide fuel cell system according to claim 9 of the present invention, the ascending utilization rate calculation means is a comparison of the above-mentioned calculated oxide utilization rate difference and the reference oxide utilization rate difference. The increase utilization rate is calculated based on the rate difference, and the fuel utilization rate setting means sets the third fuel utilization rate by adding the increase utilization rate to the second fuel utilization rate. Therefore, the third fuel utilization rate is , The value can be set according to the degree of detection error of the fuel gas flow rate measuring means.

本発明に従う固体酸化物形燃料電池システムの第１の実施形態を示す簡略断面図。FIG. 3 is a simplified cross-sectional view showing a first embodiment of a solid oxide fuel cell system according to the present invention. 図１の固体酸化物形燃料電池システムの制御系を示すブロック図。The block diagram which shows the control system of the solid oxide fuel cell system of FIG. 燃料ス流量計測手段に検知誤差がある場合のセルスタックの電出力と燃料利用率との関係を示す図。The figure which shows the relationship between the electric output of a cell stack and a fuel utilization rate when there is a detection error in a fuel flow rate measuring means. 図２の制御系による流量誤差チェック運転の流れを示すフローチャート。The flowchart which shows the flow of flow rate error check operation by the control system of FIG. 本発明に従う固体酸化物形燃料電池システムの第２の実施形態における制御系を示すブロック図。The block diagram which shows the control system in the 2nd Embodiment of the solid oxide fuel cell system according to this invention. 図５の制御系による流量誤差チェック運転の流れを示すフローチャート。The flowchart which shows the flow of flow rate error check operation by the control system of FIG. 本発明に従う固体酸化物形燃料電池システムの第３の実施形態における制御系を示すブロック図。The block diagram which shows the control system in 3rd Embodiment of the solid oxide fuel cell system according to this invention. 図７の制御系による流量誤差チェック運転の流れを示すフローチャート。The flowchart which shows the flow of the flow rate error check operation by the control system of FIG.

以下添付図面を参照して、本発明に従う固体酸化物形燃料電池システムの実施形態について説明する。まず、図１〜図４を参照して、第１の実施形態の固体酸化物形燃料電池システムについて説明する。 Hereinafter, embodiments of a solid oxide fuel cell system according to the present invention will be described with reference to the accompanying drawings. First, the solid oxide fuel cell system of the first embodiment will be described with reference to FIGS. 1 to 4.

図１において、図示の固体酸化物形燃料電池システム２は、燃料ガス（例えば、天然ガス、都市ガスなど）を改質するための改質器４と、改質器４にて水蒸気改質された燃料ガス（「改質燃料ガス」とも称する）及び酸化材ガスとしての空気の酸化及び還元によって発電を行うセルスタック６とを備えている。 In FIG. 1, the illustrated solid oxide fuel cell system 2 is steam reformed by a reformer 4 for reforming a fuel gas (for example, natural gas, city gas, etc.) and a reformer 4. It includes a fuel gas (also referred to as “reformed fuel gas”) and a cell stack 6 that generates power by oxidizing and reducing air as an oxide gas.

セルスタック６は、複数の燃料電池セル（図示せず）を積層して構成され、各燃料電池セルは酸素イオンを伝導する固体電解質と、固体電解質の一方側に設けられた燃料極と、固体電解質の他方側に設けられた酸素極とを備えており、固体電解質として例えばイットリアをドープしたジルコニアが用いられる。 The cell stack 6 is configured by stacking a plurality of fuel cell cells (not shown), and each fuel cell has a solid electrolyte that conducts oxygen ions, a fuel electrode provided on one side of the solid electrolyte, and a solid. It is provided with an oxygen electrode provided on the other side of the electrolyte, and zirconia doped with itria, for example, is used as the solid electrolyte.

セルスタック６の燃料極側８の導入側は、改質燃料ガス送給ライン１０を介して改質器４に接続され、この改質器４は、燃料ガス供給ライン１２を介して燃料ガスを供給するための燃料ガス供給源１４（例えば、埋設管や燃料ガスタンクなど）に接続されている。燃料ガス供給ライン１２には、燃料ガスを供給するための燃料ガスブロア１６が配設され、またこの燃料ガスブロア１６の下流側に燃料ガス流量計測手段１７（例えば、燃料ガス流量計測センサ）が配設されている。燃料ガスブロア１６は燃料ガス供給源１４からの燃料ガスを改質器４に供給し、その回転数が増大（又は減少）すると、燃料ガス供給ライン１２を通して供給される燃料ガスの供給流量が増大（又は減少）し、燃料ガス流量計測手段１７は、燃料ガス供給ライン１２を通して供給される燃料ガスの供給流量を計測する。この燃料ガス供給源１４、燃料ガス供給ライン１２及び燃料ガスブロア１６は、燃料ガスを供給するための燃料ガス供給手段を構成する。 The introduction side of the fuel electrode side 8 of the cell stack 6 is connected to the reformer 4 via the reformed fuel gas supply line 10, and the reformer 4 supplies fuel gas via the fuel gas supply line 12. It is connected to a fuel gas supply source 14 for supplying (for example, a buried pipe, a fuel gas tank, or the like). A fuel gas blower 16 for supplying fuel gas is provided in the fuel gas supply line 12, and a fuel gas flow rate measuring means 17 (for example, a fuel gas flow rate measuring sensor) is provided on the downstream side of the fuel gas blower 16. Has been done. The fuel gas blower 16 supplies the fuel gas from the fuel gas supply source 14 to the reformer 4, and when the number of rotations thereof increases (or decreases), the supply flow rate of the fuel gas supplied through the fuel gas supply line 12 increases (). Or decrease), and the fuel gas flow rate measuring means 17 measures the supply flow rate of the fuel gas supplied through the fuel gas supply line 12. The fuel gas supply source 14, the fuel gas supply line 12, and the fuel gas blower 16 constitute a fuel gas supply means for supplying the fuel gas.

また、セルスタック６の酸素極側１８の導入側は、空気送給ライン２０（酸化材ガス送給ラインとして機能する）を介して酸化材ガスとしての空気を予熱するための空気予熱器２２（酸化材ガス余熱器として機能する）に接続され、この空気予熱器２２は、空気供給ライン２４（酸化材供給ラインとして機能する）を介して酸化材ブロアとしての空気ブロア２６に接続され、空気供給ライン２０には、酸化材ガスとしての空気の流量を計測するための空気流量計測手段２７（酸化材ガス流量計測手段として機能する）が配設され、この空気流量計測手段２７は空気供給ライン２０を通して供給される空気の供給流量を計測する。この空気ブロア２６の回転数が上がる（又は下がる）と、空気供給ライン２４を通して供給される空気の供給量が増大（又は減少）し、空気供給ライン２４及び空気ブロア２６は、酸化材ガスとしての空気を供給するための空気供給手段（酸化材ガス供給手段として機能する）を構成する。 Further, the introduction side of the oxygen electrode side 18 of the cell stack 6 is an air preheater 22 (which functions as an oxide gas supply line) for preheating air as an oxide gas via an air supply line 20 (functions as an oxide gas supply line). Connected to an oxidant gas preheater), the air preheater 22 is connected to an air blower 26 as an oxidant blower via an air supply line 24 (which functions as an oxidant supply line) to supply air. The line 20 is provided with an air flow rate measuring means 27 (which functions as an oxide gas flow rate measuring means) for measuring the flow rate of air as an oxide gas, and the air flow rate measuring means 27 is an air supply line 20. Measure the supply flow rate of air supplied through. When the rotation speed of the air blower 26 increases (or decreases), the amount of air supplied through the air supply line 24 increases (or decreases), and the air supply line 24 and the air blower 26 serve as an oxide gas. It constitutes an air supply means (functioning as an oxide gas supply means) for supplying air.

セルスタック６の燃料極側８及び酸素極側１８の流出側には燃焼空間２８が設けられ、燃料極側８から流出された燃料ガス（「反応燃料ガス」とも称する）と酸素極側１８から流出された空気（酸化材ガス）とがそれぞれこの燃焼空間２８に送給されて燃焼される。この燃焼空間２８は燃焼排気ガスライン３０を介して空気予熱器２２に接続され、この空気予熱器２２には燃焼排気ガス排出ライン３２が接続されている。 A combustion space 28 is provided on the outflow side of the fuel pole side 8 and the oxygen pole side 18 of the cell stack 6, and the fuel gas (also referred to as “reaction fuel gas”) flowing out from the fuel pole side 8 and the oxygen pole side 18 are provided. The outflowed air (oxidant gas) is sent to the combustion space 28 and burned. The combustion space 28 is connected to an air preheater 22 via a combustion exhaust gas line 30, and a combustion exhaust gas discharge line 32 is connected to the air preheater 22.

この実施形態では、セルスタック６、改質器４及び空気余熱器２２が電池ハウジング３４内に収容されている。電池ハウジング３４の内面又は外面、或いはその両面には断熱材が配設され、この電池ハウジング３４が高温状態に保たれる高温空間３６を規定し、セルスタック６、改質器４及び空気余熱器２２は、この高温空間３６に収容されて高温状態に保たれる。 In this embodiment, the cell stack 6, the reformer 4, and the air preheater 22 are housed in the battery housing 34. Insulation is provided on the inner surface, the outer surface, or both sides of the battery housing 34 to define a high temperature space 36 in which the battery housing 34 is kept in a high temperature state, and the cell stack 6, the reformer 4, and the air preheater are defined. 22 is housed in the high temperature space 36 and kept in a high temperature state.

この固体酸化物形燃料電池システム２では、改質器４には水供給ライン３８を介して水供給源４０（例えば、純水タンクなど）が接続され、この水供給ライン３８に水ポンプ４２が配設されている。この水ポンプ４２の回転数が上がる（又は下がる）と、水供給ライン３８を通して供給される改質用水の供給量が増大（又は減少）し、水供給ライン３８及び水ポンプ４２は、改質用水を供給するための水供給手段を構成する。尚、この形態では、水供給源４０からの水を供給しているが、このような構成に代えて、燃焼排気ガスに含まれる水蒸気を凝縮して回収し、この回収した凝縮水を改質器４に供給して改質用水として利用するように構成することもできる。 In the solid oxide fuel cell system 2, a water supply source 40 (for example, a pure water tank) is connected to the reformer 4 via a water supply line 38, and a water pump 42 is connected to the water supply line 38. It is arranged. When the rotation speed of the water pump 42 increases (or decreases), the supply amount of reforming water supplied through the water supply line 38 increases (or decreases), and the water supply line 38 and the water pump 42 increase (or decrease) the reforming water. Construct a water supply means for supplying water. In this form, water is supplied from the water supply source 40. Instead of such a configuration, water vapor contained in the combustion exhaust gas is condensed and recovered, and the recovered condensed water is reformed. It can also be configured to be supplied to the vessel 4 and used as reforming water.

この固体酸化物形燃料電池システム２の稼動運転は、次のようにして行われる。燃料ガス供給源１４からの燃料ガスが燃料ガス供給ライン１２を通して改質器４に供給されると共に、水供給源４０からの改質用水が水供給ライン３８を通して改質器４に供給される。改質器４においては、燃料ガスが水（水蒸気）により水蒸気改質され、水蒸気改質された燃料ガス（改質燃料ガス）が改質燃料ガス送給ライン１０を通してセルスタック６の燃料極側８に送給される。また、空気ブロア２６からの空気は、空気供給ライン２４を通して空気予熱器２２に供給され、この空気予熱器２２において燃焼排気ガスとの間で熱交換されて加温された後に、空気送給ライン２０を通してセルスタック６の酸素極側１８に送給される。 The operation of the solid oxide fuel cell system 2 is performed as follows. The fuel gas from the fuel gas supply source 14 is supplied to the reformer 4 through the fuel gas supply line 12, and the reforming water from the water supply source 40 is supplied to the reformer 4 through the water supply line 38. In the reformer 4, the fuel gas is steam reformed with water (steam), and the steam reformed fuel gas (reformed fuel gas) passes through the reformed fuel gas supply line 10 to the fuel electrode side of the cell stack 6. It will be sent to 8. Further, the air from the air blower 26 is supplied to the air preheater 22 through the air supply line 24, and after being heated by heat exchange with the combustion exhaust gas in the air preheater 22, the air supply line is heated. It is supplied to the oxygen electrode side 18 of the cell stack 6 through 20.

セルスタック６の燃料極側８は改質燃料ガスを酸化し、またその酸素極側１８は空気中の酸素を還元し、燃料極側８の酸化及び酸素極側１８の還元による電気化学反応により発電が行われる。燃料極側８からの反応燃料ガス及び酸素極側１８からの空気は燃焼空間２８に流出され、空気中の酸素を利用して反応燃料ガス（余剰燃料ガスを含んでいる）が燃焼され、この燃焼熱によりセルスタック６、改質器４及び空気予熱器２２が加熱される。 The fuel electrode side 8 of the cell stack 6 oxidizes the reformed fuel gas, and the oxygen electrode side 18 reduces oxygen in the air by an electrochemical reaction due to the oxidation of the fuel electrode side 8 and the reduction of the oxygen electrode side 18. Power is generated. The reaction fuel gas from the fuel electrode side 8 and the air from the oxygen electrode side 18 flow out to the combustion space 28, and the reaction fuel gas (including surplus fuel gas) is burned using the oxygen in the air, and this The cell stack 6, the reformer 4, and the air preheater 22 are heated by the heat of combustion.

燃焼空間２８からの燃焼排気ガスは燃焼排気ガスライン３０を通して空気予熱器２２に送給され、この空気予熱器２２において空気ブロア２６からの空気との熱交換に利用されて燃焼排気ガス排出ライン３２を通して外部に排出される。 The combustion exhaust gas from the combustion space 28 is supplied to the air preheater 22 through the combustion exhaust gas line 30, and is used in the air preheater 22 for heat exchange with the air from the air blower 26 to be used in the combustion exhaust gas discharge line 32. It is discharged to the outside through.

尚、燃焼排気ガスの廃熱を温水として貯える貯湯タンクを備えた貯湯装置を設け、更にこの貯湯装置に関連して、燃焼排気ガス排出ライン３２を通して流れる燃焼排気ガスとの間で熱交換を行う熱交換器を燃焼排気ガス排出ライン３２に配設し、この熱交換器における熱交換により加温された温水を貯湯装置の貯湯タンクで貯えるようにしてもよい。 A hot water storage device equipped with a hot water storage tank for storing waste heat of combustion exhaust gas as hot water is provided, and heat exchange is performed with the combustion exhaust gas flowing through the combustion exhaust gas discharge line 32 in connection with this hot water storage device. The heat exchanger may be arranged in the combustion exhaust gas discharge line 32, and the hot water heated by the heat exchange in the heat exchanger may be stored in the hot water storage tank of the hot water storage device.

この固体酸化物形燃料電池システム２は、図２に示す制御系により制御される。図１とともに図２を参照して、固体酸化物形燃料電池システム２は、これを作動制御するためのコントローラ５２を備え、このコントローラ５２は、例えばマイクロプロセッサなどから構成される。燃料ガス流量計測手１７（燃料ガス流量計測センサ）及び酸化材ガス流量計測手段としての空気流量計測手段２７（空気流量計測センサ）からの計測信号は、このコントローラ５２に送給される。 The solid oxide fuel cell system 2 is controlled by the control system shown in FIG. With reference to FIG. 1 and FIG. 2, the solid oxide fuel cell system 2 includes a controller 52 for controlling its operation, and the controller 52 is composed of, for example, a microprocessor or the like. The measurement signals from the fuel gas flow rate measuring hand 17 (fuel gas flow rate measuring sensor) and the air flow rate measuring means 27 (air flow rate measuring sensor) as the oxide gas flow rate measuring means are sent to the controller 52.

また、セルスタック６又はその近傍の温度（所謂、セルスタック６の作動温度）を検出するための温度検出手段５４（温度センサ）が設けられ、この温度検出手段５４からの検知信号がコントローラ５２に送給される。更に、セルスタック６の発電出力ライン（図示せず）には、直流電力を交流電力に変換するためのインバータ５６が設けられ、セルスタック６の発電電力はこのインバータ５６にて交流電力に変換された後に電力負荷（図示せず）に送給される。このインバータ５６に関連して、セルスタック６の発電出力を検知するための発電出力検知手段５８が設けられ、この発電出力検知手段５６からの検知信号もコントローラ５２に送給される。 Further, a temperature detecting means 54 (temperature sensor) for detecting the temperature of the cell stack 6 or its vicinity (so-called operating temperature of the cell stack 6) is provided, and the detection signal from the temperature detecting means 54 is sent to the controller 52. Will be sent. Further, the power generation output line (not shown) of the cell stack 6 is provided with an inverter 56 for converting DC power into AC power, and the generated power of the cell stack 6 is converted into AC power by this inverter 56. After that, it is sent to the power load (not shown). In connection with the inverter 56, a power generation output detecting means 58 for detecting the power generation output of the cell stack 6 is provided, and a detection signal from the power generation output detecting means 56 is also sent to the controller 52.

このコントローラ５２は、制御手段６０、温度差演算手段６２、燃料利用率設定手段６４、空気利用率設定手段６６（酸化材利用率設定手段として機能する）、流量誤差判定手段６８、タイマ手段７０及びメモリ手段７２を含んでいる。制御手段６０は、燃料ガスブロア１６、空気ブロア２６（酸化材ガスブロア）、水ポンプ４２及びインバータ５６を所要の通りに作動制御する。また、温度差演算手段６２は、後述する第１燃料利用率でもって運転するときの第１温度状態と第２燃料利用率でもって運転するときの第２温度状態の温度差を演算する。燃料利用率設定手段６４は後述する如く燃料利用率を設定し、空気利用率設定手段６６（酸化材利用率設定手段として機能する）は後述する如く空気利用率（酸化材利用率）を設定し、流量誤差判定手段６８は後述する如くして燃料ガス流量計測手段５４に検知誤差ありとの判定をする。 The controller 52 includes a control means 60, a temperature difference calculation means 62, a fuel utilization rate setting means 64, an air utilization rate setting means 66 (functioning as an oxide utilization rate setting means), a flow rate error determination means 68, a timer means 70, and the like. The memory means 72 is included. The control means 60 controls the operation of the fuel gas blower 16, the air blower 26 (oxidant gas blower), the water pump 42, and the inverter 56 as required. Further, the temperature difference calculating means 62 calculates the temperature difference between the first temperature state when operating with the first fuel utilization rate and the second temperature state when operating with the second fuel utilization rate, which will be described later. The fuel utilization rate setting means 64 sets the fuel utilization rate as described later, and the air utilization rate setting means 66 (which functions as an oxide utilization rate setting means) sets the air utilization rate (oxidant utilization rate) as described later. The flow rate error determining means 68 determines that the fuel gas flow rate measuring means 54 has a detection error as described later.

また、タイマ手段７０は、後述する利用率値優先運転が安定するまでの第１設定時間（例えば、１０〜３０分程度に設定される）及び利用率上昇運転が安定するまでの第２設定時間（例えば、１〜３時間程度に設定される）などを計時する。更に、メモリ手段７２には、セルスタック６の発電出力と燃料利用率（「Ｕｆ」とも表現する）との関係を示す発電出力−Ｕｆマップ、セルスタック６の発電出力と空気利用率（「Ｕａ」とも表現する）との関係を示す発電出力−Ｕａマップ、第１設定時間、第２設定時間、利用率上昇運転で設定される第２燃料利用率及び燃料ガス流量計測手段５４に検知誤差ありとの判定をしたときに設定される第３燃料利用率などが登録されている。 Further, the timer means 70 has a first set time (for example, set to about 10 to 30 minutes) until the utilization rate priority operation, which will be described later, stabilizes, and a second set time until the utilization rate increase operation stabilizes. (For example, it is set to about 1 to 3 hours) and so on. Further, the memory means 72 has a power generation output-Uf map showing the relationship between the power generation output of the cell stack 6 and the fuel utilization rate (also referred to as "Uf"), and the power generation output and the air utilization rate of the cell stack 6 ("Ua"). There is a detection error in the power generation output-Ua map, the first set time, the second set time, the second fuel utilization rate set in the utilization rate increase operation, and the fuel gas flow rate measuring means 54, which indicate the relationship with). The third fuel utilization rate, etc., which is set when the determination is made, is registered.

この固体酸化物形燃料電池システム２では、次の通りにして燃料ガス流量計測手段１７の流量誤差のチェックが行われる。主として図２及び図４を参照して、この流量誤差のチェックは、セルスタック６の発電出力が安定した運転状態に行われる。セルスタック６の発電出力が定格出力（例えば、７００Ｗ）になると、ステップＳ１からステップＳ２に進み、燃料利用率（Ｕｆ）及び空気利用率（Ｕａ）を一定にした利用率値優先運転が行われる。即ち、発電出力検知手段５８の検知出力が定格出力になると、燃料利用率設定手段６４は、メモリ手段７２に登録された発電出力−Ｕｆマップに基づき定格出力に対応する燃料利用率、即ち第１燃料利用率（例えば、７８％）に設定し、空気利用率設定手段６６は、メモリ手段７２に登録された発電出力−Ｕａマップに基づき定格出力に対応する空気利用率、即ち第１空気利用率（例えば、３８％）を設定し、第１燃料利用率及び第１空気利用率を一定に保持した利用率値優先運転が行われ、このような利用率値優先運転では、制御手段６０は、第１燃料利用率となるように燃料ガスブロア１６を制御するとともに、第１空気利用率となるように空気ブロア２６を制御する。 In the solid oxide fuel cell system 2, the flow rate error of the fuel gas flow rate measuring means 17 is checked as follows. Mainly referring to FIGS. 2 and 4, this flow rate error check is performed in an operating state in which the power generation output of the cell stack 6 is stable. When the power generation output of the cell stack 6 reaches the rated output (for example, 700 W), the process proceeds from step S1 to step S2, and the utilization rate value priority operation with the fuel utilization rate (Uf) and the air utilization rate (Ua) constant is performed. .. That is, when the detected output of the power generation output detecting means 58 reaches the rated output, the fuel utilization rate setting means 64 has the fuel utilization rate corresponding to the rated output based on the power generation output-Uf map registered in the memory means 72, that is, the first. The fuel utilization rate (for example, 78%) is set, and the air utilization rate setting means 66 is set to the air utilization rate corresponding to the rated output based on the power generation output-Ua map registered in the memory means 72, that is, the first air utilization rate. (For example, 38%) is set, and the utilization rate value priority operation is performed in which the first fuel utilization rate and the first air utilization rate are kept constant. In such utilization rate value priority operation, the control means 60 is used. The fuel gas blower 16 is controlled so as to have the first fuel utilization rate, and the air blower 26 is controlled so as to have the first air utilization rate.

この利用率値優先運転が第１設定時間（例えば、１０分間）継続すると、ステップＳＳ３からステップＳ４に進み、温度検知手段５４はセルスタック６の温度を検知し、この検知信号がコントローラ５２に送給され、その検知温度（Ｔ１）がメモリ手段７２に記憶される。 When this utilization rate value priority operation continues for the first set time (for example, 10 minutes), the process proceeds from step SS3 to step S4, the temperature detecting means 54 detects the temperature of the cell stack 6, and this detection signal is sent to the controller 52. It is supplied and its detection temperature (T1) is stored in the memory means 72.

このように利用率値優先運転におけるセルスタック６の温度状態を検知した後、燃料利用率設定手段６４は、第１燃料利用率よりも高い第２燃料利用率（例えば、８０％）を設定し（ステップＳ５）、この上昇した第２燃料利用率による利用率上昇運転を行う。尚、この利用率上昇運転においては、空気利用率は利用率値優先運転における第１空気利用率（例えば、３８％）に設定され、制御手段６０は、第２燃料利用率となるように燃料ガスブロア１６を制御するとともに、第１空気利用率となるように空気ブロア２６を制御する。 After detecting the temperature state of the cell stack 6 in the utilization rate value priority operation in this way, the fuel utilization rate setting means 64 sets the second fuel utilization rate (for example, 80%) higher than the first fuel utilization rate. (Step S5), the utilization rate increasing operation is performed by the increased second fuel utilization rate. In this utilization rate increase operation, the air utilization rate is set to the first air utilization rate (for example, 38%) in the utilization rate value priority operation, and the control means 60 uses fuel so as to be the second fuel utilization rate. The gas blower 16 is controlled, and the air blower 26 is controlled so as to have a first air utilization rate.

そして、このような利用率上昇運転が第２所定時間（例えば、２時間）継続して行われ、この運転状態が安定すると、ステップＳ５からステップＳ６を経てステップＳ７に進み、温度検知手段５４はセルスタック６の温度を検知し、この検知温度（Ｔ２）がメモリ手段７２に記憶される。 Then, such an operation for increasing the utilization rate is continuously performed for a second predetermined time (for example, 2 hours), and when this operating state becomes stable, the process proceeds from step S5 to step S6 to step S7, and the temperature detecting means 54 The temperature of the cell stack 6 is detected, and the detected temperature (T2) is stored in the memory means 72.

このように利用率値優先運転におけるセルスタック６の温度状態と利用率上昇運転におけるセルスタック６の温度状態の検知が行われると、ステップＳ８において、温度差演算手段６２は、これら温度状態の温度差、即ち利用率優先運転における検知温度（Ｔ１）と利用率値上昇運転における検知温度（Ｔ２）との温度差（ΔＴ）を演算する（ΔＴ＝Ｔ１−Ｔ２）。利用率値優先運転から利用率上昇運転に切り替えると、空気利用率については第１空気利用率（例えば、３８％）に維持した状態において、燃料利用率については第１燃料利用率（例えば、７８％）から第２燃料利用率（例えば、８０％）に上昇するので、セルスタック６で発電に寄与する燃料ガスの消費量が多くなり、従って、セルスタック６の下流側の燃焼空間２８で燃料される燃料ガスが少なくなり、セルスタック６の温度は幾分低下するようになる（例えば、７４３℃程度から７４０℃程度に低下する）。 When the temperature state of the cell stack 6 in the utilization rate value priority operation and the temperature state of the cell stack 6 in the utilization rate increase operation are detected in this way, in step S8, the temperature difference calculation means 62 determines the temperature of these temperature states. The difference, that is, the temperature difference (ΔT) between the detection temperature (T1) in the utilization rate priority operation and the detection temperature (T2) in the utilization rate value increase operation is calculated (ΔT = T1-T2). When switching from the utilization rate priority operation to the utilization rate increase operation, the air utilization rate is maintained at the first air utilization rate (for example, 38%), and the fuel utilization rate is the first fuel utilization rate (for example, 78%). %) Increases to the second fuel utilization rate (eg, 80%), which increases the consumption of fuel gas that contributes to power generation in the cell stack 6, and therefore fuel in the combustion space 28 downstream of the cell stack 6. The amount of fuel gas produced is reduced, and the temperature of the cell stack 6 is lowered to some extent (for example, it is lowered from about 743 ° C. to about 740 ° C.).

ここで、燃料ガス流量計測手段１７の検知誤差について説明すると、一般的に、このような固体酸化物形燃料電池システム２に用いられる燃料ガス流量計測手段１７には検知誤差があり、例えば±３％の許容範囲のものが採用されている。この燃料ガス流量計測手段１７に検知誤差がない場合、燃料ガス流量計測手段１７の計測値が燃料ガスの実際の供給流量となり、この場合におけるセルスタック６の発電出力と燃料利用率との関係は、図３に実線Ａで示すようになり、この実線で示す燃料利用率となるように燃料ガスブロア１６が制御される。 Here, the detection error of the fuel gas flow rate measuring means 17 will be described. Generally, the fuel gas flow rate measuring means 17 used in such a solid oxide fuel cell system 2 has a detection error, for example, ± 3. Those with an allowable range of% are adopted. If there is no detection error in the fuel gas flow rate measuring means 17, the measured value of the fuel gas flow rate measuring means 17 becomes the actual supply flow rate of the fuel gas, and the relationship between the power generation output of the cell stack 6 and the fuel utilization rate in this case is , The solid line A is shown in FIG. 3, and the fuel gas blower 16 is controlled so as to have the fuel utilization rate shown by the solid line.

ところが、燃料ガス流量計測手段１７が実際の供給流量値よりも少ない値を示して、例えば−３％の検知誤差がある場合、実際にはこの計測値よりも＋３％多くの燃料ガスが供給されるプラス側の制御誤差が生じるようになり、従って、この場合の実際の燃料利用率は、設定された燃料利用率（即ち、実線Ａで示す燃料利用率）よりも低く、セルスタック６の発電出力と燃料利用率との関係は、図３に破線Ｂで示すようになる。一方、燃料ガス流量計測手段１７が実際の供給流量値よりも多い値を示して、例えば＋３％の検知誤差がある場合、実際にはこの計測値よりも−３％少ない燃料ガスが供給されるマイナス側の制御誤差を生じるようになり、この場合の実際の燃料利用率は、設定された燃料利用率（即ち、実線Ａで示す燃料利用率）よりも高く、セルスタック６の発電出力と燃料利用率との関係は、図３に一点鎖線Ｃで示すようになる。 However, if the fuel gas flow rate measuring means 17 shows a value smaller than the actual supply flow rate value, for example, if there is a detection error of -3%, the fuel gas is actually supplied + 3% more than this measured value. Therefore, the actual fuel utilization rate in this case is lower than the set fuel utilization rate (that is, the fuel utilization rate indicated by the solid line A), and the power generation of the cell stack 6 is generated. The relationship between the output and the fuel utilization rate is shown by the broken line B in FIG. On the other hand, if the fuel gas flow rate measuring means 17 shows a value larger than the actual supply flow rate value and there is a detection error of, for example, + 3%, the fuel gas actually supplied is -3% less than this measured value. A control error on the negative side will occur, and the actual fuel utilization rate in this case is higher than the set fuel utilization rate (that is, the fuel utilization rate indicated by the solid line A), and the power output and fuel of the cell stack 6 The relationship with the utilization rate is shown by the one-point chain line C in FIG.

この燃料ガス流量計測手段１７の検知誤差は、利用率値優先運転における第１検知温度（Ｔ１）と利用率上昇運転における第２検知温度（Ｔ２）との演算温度差（ΔＴ）にも現れ、この第１の実施形態では、かかる検知温度（Ｔ１，Ｔ２）の演算温度差（ΔＴ）に着目して燃料ガス流量計測手段１７の検知誤差をチェックしている。即ち、燃料ガス流量計測手段１７に検知誤差がない場合、セルスタック６の温度低下幅は、上述したように、例えば約３℃程度となる。一方、燃料ガス流量計測手段１７の検知誤差によりプラス側の制御誤差（換言すると、増量側の誤差）が存在する場合、この検知温度の演算温度差（ΔＴ）（即ち、温度低下幅）は、検知誤差がない場合に比して小さくなる。 The detection error of the fuel gas flow rate measuring means 17 also appears in the calculated temperature difference (ΔT) between the first detection temperature (T1) in the utilization rate value priority operation and the second detection temperature (T2) in the utilization rate increase operation. In this first embodiment, the detection error of the fuel gas flow rate measuring means 17 is checked by paying attention to the calculated temperature difference (ΔT) of the detected temperatures (T1, T2). That is, when the fuel gas flow rate measuring means 17 has no detection error, the temperature drop width of the cell stack 6 is, for example, about 3 ° C. as described above. On the other hand, when there is a control error on the plus side (in other words, an error on the increase side) due to the detection error of the fuel gas flow rate measuring means 17, the calculated temperature difference (ΔT) (that is, the temperature decrease width) of this detection temperature is It is smaller than when there is no detection error.

更に説明すると、利用率値優先運転から利用率上昇運転（例えば、燃料利用率を２．０ポイント上昇させる運転）に切り換える過程で、燃料ガス流量計測手段１７に検知誤差、特にマイナス側への誤差が拡大していると、燃料ガスがより多く流れるために温度の低下幅は想定よりも小さくなり、計測値においてマイナス側に例えば２％の検知誤差が新たに発生し、この検知温度の演算温度差（ΔＴ）（即ち、温度低下幅）は、例えば０．８℃程度となり、検知誤差がない場合の温度低下幅の約３℃よりも小さくなる。 Further explaining, in the process of switching from the utilization rate value priority operation to the utilization rate increase operation (for example, the operation of increasing the fuel utilization rate by 2.0 points), the fuel gas flow rate measuring means 17 has a detection error, particularly an error to the minus side. When is expanding, the amount of decrease in temperature becomes smaller than expected because more fuel gas flows, and a new detection error of, for example, 2% occurs on the negative side of the measured value, and the calculated temperature of this detected temperature. The difference (ΔT) (that is, the temperature decrease width) is, for example, about 0.8 ° C., which is smaller than the temperature decrease width of about 3 ° C. when there is no detection error.

このようなことから、検知温度の演算温度差（ΔＴ）を演算した後は、ステップＳ９においてこの検知温度の演算温度差（ΔＴ）（温度低下幅）が基準温度差よりも小さいかが判断される。基準温度差としては、例えば、検知誤差がない場合における温度低下幅の例えば３．１℃程度に設定される。即ち、流量誤差判定手段６８は、検知温度の演算温度差（ΔＴ）とこの基準温度差（例えば、３，１℃）とを対比し、この演算温度差（ΔＴ）が基準温度差よりも小さいときには燃料ガス流量計測手段１７の計測値と実際の燃料ガスの流量との間にプラス側の乖離があり、このような場合、流量誤差判定手段６８は、燃料ガス流量計測手段１７にプラス側の制御誤差ありと判定する（ステップＳ１０）。 Therefore, after calculating the calculated temperature difference (ΔT) of the detected temperature, it is determined in step S9 whether the calculated temperature difference (ΔT) (temperature decrease width) of the detected temperature is smaller than the reference temperature difference. To. The reference temperature difference is set to, for example, about 3.1 ° C., which is the temperature drop range when there is no detection error. That is, the flow rate error determining means 68 compares the calculated temperature difference (ΔT) of the detected temperature with the reference temperature difference (for example, 3.1 ° C.), and the calculated temperature difference (ΔT) is smaller than the reference temperature difference. Occasionally, there is a positive deviation between the measured value of the fuel gas flow rate measuring means 17 and the actual flow rate of the fuel gas. In such a case, the flow rate error determining means 68 is on the positive side of the fuel gas flow rate measuring means 17. It is determined that there is a control error (step S10).

流量誤差判定手段６８がかく判定すると、燃料利用率設定手段６４は燃料利用率として第３燃料利用率（例えば、８２％）を設定する（ステップＳ１１）ことで、システムの発電効率をより高めることができる。尚、この検知温度の演算温度差（ΔＴ）が基準温度以上であると、燃料ガス流量計測手段１７に検知誤差が存在しないか、或いは存在していてもマイナス側の制御誤差（換言すると、不足側の誤差）であるために、燃料利用率はそのまま維持される。 When the flow rate error determining means 68 determines in this way, the fuel utilization rate setting means 64 sets the third fuel utilization rate (for example, 82%) as the fuel utilization rate (step S11), thereby further increasing the power generation efficiency of the system. Can be done. If the calculated temperature difference (ΔT) of the detected temperature is equal to or higher than the reference temperature, the fuel gas flow rate measuring means 17 does not have a detection error, or even if it exists, a negative control error (in other words, insufficient). The fuel utilization rate is maintained as it is because of the error on the side).

この第１の実施形態では、燃料ガス流量計測手段１７にプラス側の制御誤差が存在していると第３燃料利用率（例えば、８２％）に上昇させているが、燃料利用率の上昇程度については、燃料ガス流量計測手段１７のプラス側の検知誤差に応じて、次のように構成するようにしてもよい。即ち、コントローラ５２に上昇利用率を演算するための上昇利用率演算手段（図示せず）を含め、この上昇率演算手段により第２燃料利用率から上昇させる上昇利用率を演算するようにしてもよい。 In this first embodiment, if the fuel gas flow rate measuring means 17 has a control error on the positive side, the fuel utilization rate is increased to the third fuel utilization rate (for example, 82%), but the degree of increase in the fuel utilization rate is high. May be configured as follows according to the detection error on the positive side of the fuel gas flow rate measuring means 17. That is, even if the controller 52 includes an ascending utilization rate calculating means (not shown) for calculating the ascending utilization rate, the ascending utilization rate is calculated by the ascending utilization rate calculating means to be increased from the second fuel utilization rate. Good.

上昇利用率演算手段は、利用率値優先運転におけるセルスタック６の温度（温度検知手段５４の第１検知温度（Ｔ１））及び上昇利用率運転におけるセルスタック６の温度（温度検知手段５４の第２検知温度（Ｔ２））の演算温度差（ΔＴ）と基準温度差との温度差、即ち比較温度差（ΔＴＨ）を演算し、この比較温度差（ΔＴＳ）の値に基づいて上昇利用率を演算する。この比較温度差（ΔＴＳ）が大きい（又は小さい）と、燃料ガス流量計測手段１７の計測値と実際の燃料ガスの流量との間に大きな（又は小さな）乖離があり、従って、上昇利用率演算手段により演算される上昇利用率の値も大きく（又は小さく）なる。 The increase utilization rate calculation means is the temperature of the cell stack 6 in the utilization rate value priority operation (first detection temperature (T1) of the temperature detecting means 54) and the temperature of the cell stack 6 in the increase utilization rate operation (the first of the temperature detection means 54). 2 The temperature difference between the calculated temperature difference (ΔT) of the detected temperature (T2)) and the reference temperature difference, that is, the comparative temperature difference (ΔTH) is calculated, and the increase utilization rate is calculated based on the value of this comparative temperature difference (ΔTS). Calculate. When this comparative temperature difference (ΔTS) is large (or small), there is a large (or small) deviation between the measured value of the fuel gas flow rate measuring means 17 and the actual fuel gas flow rate, and therefore, the increase utilization rate calculation. The value of the ascending utilization rate calculated by the means also becomes large (or small).

この上昇利用率演算手段による上昇利用率は、例えば、式（２）、
上昇利用率＝α×比較温度差（ΔＴＳ）
を用いて演算することができる。ここで、αは係数であって、この係数αは、実験的に導き出される値である。このように上昇利用率を演算し、第２燃料利用率にこの上昇利用率を加算して第３燃料利用率を算出することによって、燃料ガス流量計測手段５４の測定誤差の程度を考慮して上昇すべき燃料利用率、即ち第３燃料利用率を設定することができる。 The increase utilization rate by the increase utilization rate calculation means is, for example, the equation (2),
Increased utilization rate = α × comparative temperature difference (ΔTS)
Can be calculated using. Here, α is a coefficient, and this coefficient α is a value derived experimentally. By calculating the rising utilization rate in this way and adding this rising utilization rate to the second fuel utilization rate to calculate the third fuel utilization rate, the degree of measurement error of the fuel gas flow rate measuring means 54 is taken into consideration. The fuel utilization rate to be increased, that is, the third fuel utilization rate can be set.

例えば、利用率値優先運転における温度検知手段５４の第１検知温度（Ｔ１）と上昇利用率運転における温度検知手段５４の第２検知温度（Ｔ２）との演算温度差（ΔＴ）は、燃料ガス流量計測手段５４に検知誤差に変化がないときには例えば３．１℃となり、基準温度差（例えば、３．１℃）と一致し、比較温度差（ΔＴＨ）はゼロとなる。一方、この演算温度差（ΔＴ）が上述したように例えば０．８℃であると、比較温度差（ΔＴＨ）は、２．３℃となり、上昇利用率演算手段は、上記式（２）を用い、係数（例えば、０．６５）にこの比較温度差（ΔＴＨ）の２．３を積算し、この積算結果の１．５ポイントを第２燃料利用率（例えば、８０％）に加算した８１．５％が第３燃料利用率として設定される。 For example, the calculated temperature difference (ΔT) between the first detected temperature (T1) of the temperature detecting means 54 in the utilization rate value priority operation and the second detected temperature (T2) of the temperature detecting means 54 in the increased utilization rate operation is the fuel gas. When there is no change in the detection error in the flow rate measuring means 54, it becomes, for example, 3.1 ° C., which coincides with the reference temperature difference (for example, 3.1 ° C.), and the comparative temperature difference (ΔTH) becomes zero. On the other hand, when the calculated temperature difference (ΔT) is, for example, 0.8 ° C. as described above, the comparative temperature difference (ΔTH) is 2.3 ° C., and the rising utilization rate calculation means uses the above equation (2). Using, 2.3 of this comparative temperature difference (ΔTH) was integrated into the coefficient (for example, 0.65), and 1.5 points of this integration result was added to the second fuel utilization rate (for example, 80%) 81. 5.5% is set as the third fuel utilization rate.

次いで、図５及び図６を参照して、本発明に従う固体酸化物形燃料電池システムの第２の実施形態について説明する。上述の第１の実施形態では、利用率値優先運転におけるセルスタック６の第１温度状態と上昇利用率運転におけるセルスタック６の第２温度状態における温度差を利用して燃料ガス流量計測手段の測定誤差の判定を行っているが、この第２の実施形態では、利用率値優先運転を行った後に温度優先運転を行い、この温度優先運転における空気利用率を利用して燃料ガス流量計測手段の測定誤差の判定を行っている。尚、以下の実施形態において、上述した第１の実施形態と実質上同一のものには同一の参照番号を付し、その説明を省略する。 Next, a second embodiment of the solid oxide fuel cell system according to the present invention will be described with reference to FIGS. 5 and 6. In the above-described first embodiment, the temperature difference between the first temperature state of the cell stack 6 and the second temperature state of the cell stack 6 in the utilization rate operation is used to measure the fuel gas flow rate. Although the measurement error is determined, in the second embodiment, the temperature priority operation is performed after the utilization rate value priority operation is performed, and the air utilization rate in this temperature priority operation is used to measure the fuel gas flow rate. The measurement error of is determined. In the following embodiments, substantially the same reference numbers as those in the first embodiment described above will be assigned the same reference numbers, and the description thereof will be omitted.

図５及び図６において、この第２の実施形態では、コントローラ５２Ａは、燃料利用率設定手段６４、空気利用率設定手段６４、流量誤差判定手段６８Ａ、タイマ手段７０Ａ及びメモリ手段７２Ａに加えて空気利用率演算手段７６（酸化材利用率演算手段として機能する）を備え、燃料利用率設定手段６４は、上述したように燃料利用率を設定し、また空気利用率設定手段６６は、上述したように空気利用率を設定し、空気利用率演算手段７６は空気の流量に基づいて空気利用率（第２空気利用率）を演算し、流量誤差判定手段６８Ａは、後述する如くして燃料ガス流量計測手段１７の検知誤差の有無を判定する。また、タイマ手段７０Ａは、定格運転状態が安定するまでの第１設定時間（例えば、１０〜３０分程度に設定される）及び温度優先運転が安定するまでの第２設定時間（例えば、１〜３時間程度に設定される）を計時する。更に、メモリ手段７２Ａには、セルスタック６（図１参照）の発電出力と燃料利用率との関係を示す発電出力−Ｕｆマップ、セルスタック６の発電出力と空気利用率との関係を示す発電出力−Ｕａマップ、第１設定時間、第２設定時間、温度優先運転で設定されるセルスタックの目標温度（例えば、７５０℃程度に設定される）、この温度優先運転において設定される第２燃料利用率（例えば、８０％）、燃料ガス流量計測手段５４に検知誤差ありとの判定基準となる基準空気利用率（基準酸化材利用率）及び検知誤差をしたときに設定される第３燃料利用率（例えば、８２％）などが登録されている。この第２の実施形態におけるその他の構成（固体酸化物形燃料電池システムの基本的構成を含むその他の構成）は、上述の第１の実施形態と同様である。 In FIGS. 5 and 6, in the second embodiment, the controller 52A includes air in addition to the fuel utilization rate setting means 64, the air utilization rate setting means 64, the flow rate error determination means 68A, the timer means 70A, and the memory means 72A. The utilization rate calculation means 76 (which functions as an oxide utilization rate calculation means) is provided, the fuel utilization rate setting means 64 sets the fuel utilization rate as described above, and the air utilization rate setting means 66 sets the fuel utilization rate as described above. The air utilization rate is set to, the air utilization rate calculating means 76 calculates the air utilization rate (second air utilization rate) based on the air flow rate, and the flow rate error determining means 68A calculates the fuel gas flow rate as described later. It is determined whether or not there is a detection error in the measuring means 17. Further, the timer means 70A has a first set time (for example, set to about 10 to 30 minutes) until the rated operating state stabilizes and a second set time (for example, 1 to 1) until the temperature priority operation stabilizes. (Set to about 3 hours) is timed. Further, the memory means 72A has a power generation output-Uf map showing the relationship between the power generation output of the cell stack 6 (see FIG. 1) and the fuel utilization rate, and a power generation showing the relationship between the power generation output of the cell stack 6 and the air utilization rate. Output-Ua map, 1st set time, 2nd set time, target temperature of cell stack set in temperature priority operation (for example, set to about 750 ° C), 2nd fuel set in this temperature priority operation Utilization rate (for example, 80%), reference air utilization rate (reference oxide utilization rate), which is a criterion for determining that the fuel gas flow rate measuring means 54 has a detection error, and third fuel utilization set when a detection error is made. The rate (for example, 82%) is registered. Other configurations in this second embodiment (other configurations including the basic configuration of the solid oxide fuel cell system) are the same as those in the first embodiment described above.

第２の実施形態の固体酸化物形燃料電池システムでは、次の通りにして燃料ガス流量計測手段１７の流量誤差のチェックが行われる。この流量誤差のチェックは、セルスタック６の発電出力が安定した運転状態に行われる。セルスタック６の発電出力が定格出力（例えば、７００Ｗ）になると、ステップＳ２１からステップＳ２に進み、燃料利用率（Ｕｆ）を第１燃料利用率（例えば、７８％）に、また空気利用率（Ｕａ）を第１空気利用率（例えば、３８％）に維持した利用率値優先運転が行われ、この利用率値優先運転が第１設定時間（例えば、１０分間）継続すると、ステップＳＳ２３からステップＳ２４に進み、温度優先運転が行われる。尚、ステップＳ２１からステップＳ２３までの実行内容は、上述したステップＳ１からステップＳ４までの実行内容と同様である。 In the solid oxide fuel cell system of the second embodiment, the flow rate error of the fuel gas flow rate measuring means 17 is checked as follows. This flow rate error check is performed so that the power generation output of the cell stack 6 is in a stable operating state. When the power generation output of the cell stack 6 reaches the rated output (for example, 700 W), the process proceeds from step S21 to step S2, and the fuel utilization rate (Uf) is changed to the first fuel utilization rate (for example, 78%) and the air utilization rate (for example, 78%). When the utilization rate value priority operation in which Ua) is maintained at the first air utilization rate (for example, 38%) is performed and the utilization rate value priority operation continues for the first set time (for example, 10 minutes), steps are taken from step SS23. Proceeding to S24, the temperature priority operation is performed. The execution contents from step S21 to step S23 are the same as the execution contents from step S1 to step S4 described above.

ステップＳ２４においては、制御手段６０は、セルスタック６の温度が目標温度（例えば、７５０℃）となるように制御する温度優先運転に切り替え、この目標温度となるように空気ブロア２６を制御する。また、燃料利用率設定手段６４は、第１燃料利用率（例えば、７８％）よりも高い第２燃料利用率（例えば、８０％）を設定し、制御手段６０は、この第２燃料利用率となるように燃料ガスブロア１６を制御する。 In step S24, the control means 60 switches to the temperature priority operation in which the temperature of the cell stack 6 is controlled to be the target temperature (for example, 750 ° C.), and controls the air blower 26 so as to be the target temperature. Further, the fuel utilization rate setting means 64 sets a second fuel utilization rate (for example, 80%) higher than the first fuel utilization rate (for example, 78%), and the control means 60 sets the second fuel utilization rate. The fuel gas blower 16 is controlled so as to be.

そして、このような温度優先運転が第２所定時間（例えば、２時間）継続して行われ、この運転状態が安定すると、ステップＳ２５からステップＳ２６に進み、このときの空気流量が計測され、空気利用率演算手段７６は、この計測された空気流量に基づいて第２空気利用率を演算し、この第２空気利用率がメモリ手段７２Ａに記憶される。尚、温度優先運転においては、セルスタック６は定格運転状態にあるので、空気流量から空気利用率を演算することができる。 Then, such a temperature priority operation is continuously performed for a second predetermined time (for example, 2 hours), and when this operating state is stabilized, the process proceeds from step S25 to step S26, the air flow rate at this time is measured, and the air is measured. The utilization rate calculation means 76 calculates the second air utilization rate based on the measured air flow rate, and the second air utilization rate is stored in the memory means 72A. In the temperature priority operation, since the cell stack 6 is in the rated operation state, the air utilization rate can be calculated from the air flow rate.

このように温度優先運転における空気流量に基づいて第２空気利用率が演算されると、ステップＳ２７において、この第２空気利用率が基準空気利用率より小さいかが判断される。利用率値優先運転から温度優先運転に切り替えると、燃料利用率については第２燃料利用率に上昇するので、セルスタック６で発電に寄与する燃料ガスの消費量が多くなり、従って、セルスタック６の下流側の燃焼空間で燃料される燃料ガスが少なくなってセルスタック６の温度は低下傾向になるが、温度優先運転を行っているために、セルスタック６の温度低下を抑えるように空気（酸化材ガス）の供給流量が少なくなる。 When the second air utilization rate is calculated based on the air flow rate in the temperature priority operation in this way, it is determined in step S27 whether the second air utilization rate is smaller than the reference air utilization rate. When switching from the utilization rate value priority operation to the temperature priority operation, the fuel utilization rate rises to the second fuel utilization rate, so that the consumption of fuel gas that contributes to power generation in the cell stack 6 increases, and therefore the cell stack 6 The fuel gas fueled in the combustion space on the downstream side of the cell stack 6 decreases, and the temperature of the cell stack 6 tends to decrease. However, since the temperature priority operation is performed, the air (air) is used to suppress the temperature decrease of the cell stack 6. The supply flow rate of (oxidant gas) is reduced.

このとき、燃料ガス流量計測手段１７の検知誤差は、温度優先運転における第２空気利用率にも現れ、この第２の実施形態では、かかる第２空気利用率に着目して燃料ガス流量計測手段１７の検知誤差をチェックしている。即ち、燃料ガス流量計測手段１７に検知誤差がない場合、燃料利用率を第１燃料利用率から第２燃料利用率に上昇させ、セルスタック６の温度が目標温度となるように制御すると、第２空気利用率は例えば４６％程度となる。一方、燃料ガス流量計測手段１７に検知誤差、特にプラス側の誤差が存在する場合、この第２空気利用率は、検知誤差がない場合に比して小さくなる。 At this time, the detection error of the fuel gas flow rate measuring means 17 also appears in the second air utilization rate in the temperature priority operation, and in this second embodiment, the fuel gas flow rate measuring means pays attention to the second air utilization rate. 17 detection errors are checked. That is, when there is no detection error in the fuel gas flow rate measuring means 17, the fuel utilization rate is increased from the first fuel utilization rate to the second fuel utilization rate, and the temperature of the cell stack 6 is controlled to be the target temperature. 2 The air utilization rate is, for example, about 46%. On the other hand, when the fuel gas flow rate measuring means 17 has a detection error, particularly an error on the plus side, the second air utilization rate becomes smaller than when there is no detection error.

更に説明すると、利用率値優先運転から温度優先運転に切り換えた際に燃料ガス流量計測手段１７に検知誤差、特にプラス側の誤差が存在していると、燃料ガスがより多く流れるために温度の低下幅は小さくなり、従って、このときに絞る空気量も少なくてよく、第２空気利用率は測定誤差のない場合に比して小さく、例えば、燃料ガス流量計測手段１７においてプラス側に例えば２％の検知誤差が存在していると、この第２空気利用率は４１．５％程度となる。 Further explaining, if there is a detection error in the fuel gas flow rate measuring means 17, especially an error on the positive side when switching from the utilization rate value priority operation to the temperature priority operation, the fuel gas flows more and the temperature rises. The amount of decrease is small, and therefore the amount of air to be throttled at this time may be small, and the second air utilization rate is smaller than when there is no measurement error. For example, in the fuel gas flow rate measuring means 17, for example, 2 on the positive side. If there is a detection error of%, this second air utilization rate is about 41.5%.

このようなことから、温度優先運転において空気流量が計測された後は、ステップＳ２７において第２空気利用率が基準空気利用率よりも小さいかが判断される。基準空気利用率としては、例えば、検知誤差がない場合における第２空気利用率の例えば４６％程度に設定される。 Therefore, after the air flow rate is measured in the temperature priority operation, it is determined in step S27 whether the second air utilization rate is smaller than the reference air utilization rate. The reference air utilization rate is set to, for example, about 46% of the second air utilization rate when there is no detection error.

この場合、流量誤差判定手段６８Ａは、第２空気利用率とこの基準空気利用率（例えば、４６％）とを対比し、この第２空気利用率が基準空気利用率よりも小さいときには燃料ガス流量計測手段１７の計測値と実際の燃料ガスの流量との間にプラス側の乖離があり、このような場合、流量誤差判定手段６８Ａは、燃料ガス流量計測手段１７にプラス側の誤差ありと判定する（ステップＳ２８）。 In this case, the flow rate error determining means 68A compares the second air utilization rate with the reference air utilization rate (for example, 46%), and when the second air utilization rate is smaller than the reference air utilization rate, the fuel gas flow rate. There is a positive deviation between the measured value of the measuring means 17 and the actual flow rate of the fuel gas. In such a case, the flow rate error determining means 68A determines that the fuel gas flow rate measuring means 17 has an error on the positive side. (Step S28).

流量誤差判定手段６８Ａがかく判定すると、燃料利用率設定手段６４は燃料利用率として第３燃料利用率（例えば、８２％）を設定し（ステップＳ２９）、このように燃料ガス流量計測手段１７のプラス側の測定誤差により燃料利用率を第３燃料利用率に上昇させることにより、燃料供給不足などが生じることなく発電効率をより高めることができる。尚、この第２空気利用率が基準空気利用率以上であると、燃料ガス流量計測手段１７に検知誤差が存在しないか、或いは存在していてもマイナス側の検知誤差（換言すると、不足側の誤差）であるために、燃料利用率はそのまま維持される。 When the flow rate error determining means 68A determines in this way, the fuel utilization rate setting means 64 sets the third fuel utilization rate (for example, 82%) as the fuel utilization rate (step S29), and thus the fuel gas flow rate measuring means 17 By increasing the fuel utilization rate to the third fuel utilization rate due to the measurement error on the positive side, it is possible to further improve the power generation efficiency without causing a fuel supply shortage or the like. If the second air utilization rate is equal to or higher than the reference air utilization rate, the fuel gas flow rate measuring means 17 does not have a detection error, or even if it exists, a negative detection error (in other words, a shortage side). Since it is an error), the fuel utilization rate is maintained as it is.

この第２の実施形態では、燃料ガス流量計測手段１７にプラス側の測定誤差が存在していると第３燃料利用率（例えば、８２％）に上昇させているが、燃料利用率の上昇程度については、第１の実施形態と同様に、燃料ガス流量計測手段１７のプラス側の測定誤差に応じて、上昇利用率を演算して第３燃料利用率を設定するようにしてもよい。 In this second embodiment, if there is a measurement error on the positive side in the fuel gas flow rate measuring means 17, the fuel utilization rate is increased to the third fuel utilization rate (for example, 82%), but the degree of increase in the fuel utilization rate is high. The third fuel utilization rate may be set by calculating the increase utilization rate according to the measurement error on the plus side of the fuel gas flow rate measuring means 17, as in the first embodiment.

この場合においても、コントローラ５２Ａに上昇利用率演算手段（図示せず）を含め、この上昇利用率演算手段は、温度優先運転における第２空気利用率と基準空気利用率との空気利用率差（酸化材利用率差）、即ち比較空気利用率差（比較酸化材利用率差）を演算し、この比較空気利用率差の値に基づいて上昇利用率を演算する。この比較空気利用率差が大きい（又は小さい）と、燃料ガス流量計測手段１７の計測値と実際の燃料ガスの流量との間に大きな（又は小さな）乖離があり、従って、上昇利用率演算手段により演算される上昇利用率の値も大きく（又は小さく）なる。 Also in this case, the controller 52A includes the rising utilization rate calculating means (not shown), and the rising utilization rate calculating means includes the air utilization rate difference between the second air utilization rate and the reference air utilization rate in the temperature priority operation (not shown). Oxidizing material utilization rate difference), that is, the comparative air utilization rate difference (comparative oxide utilization rate difference) is calculated, and the increase utilization rate is calculated based on the value of the comparative air utilization rate difference. When this comparative air utilization rate difference is large (or small), there is a large (or small) divergence between the measured value of the fuel gas flow rate measuring means 17 and the actual fuel gas flow rate, and therefore, the rising utilization rate calculating means. The value of the ascending utilization rate calculated by is also large (or small).

この場合、上昇利用率演算手段による上昇利用率は、例えば、式（３）、
上昇利用率＝α×比較空気利用率差
を用いて演算することができる。ここで、αは係数であって、この係数αは、実験的に導き出される値である。 In this case, the increase utilization rate by the increase utilization rate calculation means is, for example, the equation (3),
It can be calculated using the rising utilization rate = α × comparative air utilization rate difference. Here, α is a coefficient, and this coefficient α is a value derived experimentally.

例えば、基準空気利用率が４６％であるときに、この第２空気利用率が例えば４１．５％であると、第２空気利用率と基準空気利用率との比較空気利用率差は、４．５となり、上昇利用率演算手段は、上記式（３）を用い、係数（例えば、０．３５）にこの比較空気利用率差の４．５を積算して例えば１．６ポイントを算出し、第３燃料利用率として第２燃料利用率（例えば、８０％）にこの上昇利用率（例えば、１．６％）を加算した８１．６％が設定される。 For example, when the reference air utilization rate is 46% and the second air utilization rate is, for example, 41.5%, the comparison air utilization rate difference between the second air utilization rate and the reference air utilization rate is 4. The result is .5, and the rising utilization rate calculation means uses the above equation (3) and integrates 4.5 of this comparative air utilization rate difference into the coefficient (for example, 0.35) to calculate, for example, 1.6 points. As the third fuel utilization rate, 81.6% is set by adding the increased utilization rate (for example, 1.6%) to the second fuel utilization rate (for example, 80%).

次いで、図７及び図８を参照して、本発明に従う固体酸化物形燃料電池システムの第３の実施形態について説明する。上述の第２の実施形態では、利用率値優先運転を行った後に温度優先運転を行い、この温度優先運転における空気利用率を利用して燃料ガス流量計測手段の測定誤差の判定を行っているが、この第３の実施形態では、利用率値優先運転を行った後に温度優先運転を行い、この温度優先運転において燃料利用率を上昇させる前後の空気利用率差を利用して燃料ガス流量計測手段の測定誤差の判定を行っている。 Next, a third embodiment of the solid oxide fuel cell system according to the present invention will be described with reference to FIGS. 7 and 8. In the second embodiment described above, the temperature priority operation is performed after the utilization rate value priority operation is performed, and the measurement error of the fuel gas flow rate measuring means is determined by using the air utilization rate in this temperature priority operation. However, in this third embodiment, the temperature priority operation is performed after the utilization rate value priority operation is performed, and the fuel gas flow rate is measured by utilizing the difference in air utilization rate before and after increasing the fuel utilization rate in this temperature priority operation. The measurement error of the means is determined.

図７及び図８において、この第３の実施形態では、コントローラ５２Ｂは、燃料利用率設定手段６４、空気利用率設定手段６６、流量誤差判定手段６８Ｂ、空気利用率演算手段７６、タイマ手段７０Ｂ及びメモリ手段７２Ｂに加えて空気利用率差演算手段８４（酸化材利用率差演算手段として機能する）を備えている。燃料利用率設定手段６４は、上述したと同様にして燃料利用率を設定し、また空気利用率設定手段６６は、上述するように空気利用率を設定し、空気利用率演算手段７６は、上述したように空気利用率を演算する。また、空気利用率差演算手段８４は、後述するようにして第２空気利用率と第３空気利用率との利用率差、即ち演算空気利用率差（演算酸化材利用率差）を演算し、流量誤差判定手段６８Ｂは、この演算空気利用率差に基づいて燃料ガス流量計測手段１７の検知誤差の有無を後述する如く判定する。 In FIGS. 7 and 8, in the third embodiment, the controller 52B includes the fuel utilization rate setting means 64, the air utilization rate setting means 66, the flow rate error determination means 68B, the air utilization rate calculation means 76, the timer means 70B, and the like. In addition to the memory means 72B, an air utilization rate difference calculation means 84 (which functions as an oxide utilization rate difference calculation means) is provided. The fuel utilization rate setting means 64 sets the fuel utilization rate in the same manner as described above, the air utilization rate setting means 66 sets the air utilization rate as described above, and the air utilization rate calculation means 76 sets the air utilization rate as described above. Calculate the air utilization rate as described above. Further, the air utilization rate difference calculating means 84 calculates the utilization rate difference between the second air utilization rate and the third air utilization rate, that is, the calculated air utilization rate difference (calculated oxide utilization rate difference) as described later. The flow rate error determining means 68B determines whether or not there is a detection error of the fuel gas flow rate measuring means 17 based on the calculated air utilization rate difference as described later.

更に、タイマ手段７０Ｂは、定格運転状態が安定するまでの第１設定時間（例えば、１０〜３０分程度に設定される）及び第１及び第２温度優先運転が安定するまでの第２設定時間（例えば、１〜３時間程度に設定される）を計時する。更に、メモリ手段７２Ｂには、セルスタック６の発電出力と燃料利用率との関係を示す発電出力−Ｕｆマップ、セルスタック６の発電出力と空気利用率との関係を示すマップ、第１設定時間、第２設定時間、第１及び第２温度優先運転で設定されるセルスタック６の目標温度、この第２温度優先運転において設定される第２燃料利用率、燃料ガス流量計測手段５４に検知誤差ありとの判定基準となる基準空気利用率及び検知誤差と判定したときに設定される第３燃料利用率などが登録されている。この第３の実施形態におけるその他の構成（固体酸化物形燃料電池システムの基本的構成を含むその他の構成）は、上述の第２の実施形態と同様である。 Further, the timer means 70B has a first set time (for example, set to about 10 to 30 minutes) until the rated operating state stabilizes, and a second set time until the first and second temperature priority operations stabilize. (For example, it is set to about 1 to 3 hours) is clocked. Further, the memory means 72B has a power generation output-Uf map showing the relationship between the power generation output of the cell stack 6 and the fuel utilization rate, a map showing the relationship between the power generation output of the cell stack 6 and the air utilization rate, and a first set time. , 2nd set time, target temperature of cell stack 6 set in 1st and 2nd temperature priority operation, 2nd fuel utilization rate set in this 2nd temperature priority operation, detection error in fuel gas flow rate measuring means 54 The reference air utilization rate, which is the criterion for determining the existence, and the third fuel utilization rate, which is set when the detection error is determined, are registered. The other configurations in the third embodiment (other configurations including the basic configuration of the solid oxide fuel cell system) are the same as those in the second embodiment described above.

第３の実施形態の固体酸化物形燃料電池システムでは、次の通りにして燃料ガス流量計測手段１７の流量誤差のチェックが行われる。この流量誤差のチェックは、上述したと同様に、セルスタック６の発電出力が安定した運転状態に行われる。セルスタック６の発電出力が定格出力（例えば、７００Ｗ）になると、ステップＳ３１からステップＳ３２に進み、燃料利用率（Ｕｆ）を第１燃料利用率（例えば、７８％）に、また空気利用率（Ｕａ）を第１空気利用率（例えば、３８％）に維持した利用率値優先運転が行われ、この利用率値優先運転が第１設定時間（例えば、１０分間）継続すると、ステップＳ３３からステップＳ３４に進み、第１温度優先運転が行われる。尚、ステップＳ３１からステップＳ３３までの実行内容は、上述したステップＳ２１からステップＳ２３までの実行内容と同様である。 In the solid oxide fuel cell system of the third embodiment, the flow rate error of the fuel gas flow rate measuring means 17 is checked as follows. The check for the flow rate error is performed in a stable operating state when the power generation output of the cell stack 6 is as described above. When the power generation output of the cell stack 6 reaches the rated output (for example, 700 W), the process proceeds from step S31 to step S32, and the fuel utilization rate (Uf) is changed to the first fuel utilization rate (for example, 78%) and the air utilization rate (for example, 78%). When the utilization rate value priority operation in which Ua) is maintained at the first air utilization rate (for example, 38%) is performed and the utilization rate value priority operation continues for the first set time (for example, 10 minutes), steps S33 to step are performed. Proceeding to S34, the first temperature priority operation is performed. The execution contents from step S31 to step S33 are the same as the execution contents from step S21 to step S23 described above.

ステップＳ３４においては、制御手段６０は、セルスタック６の温度が目標温度（例えば、７５０℃）となるように制御する温度優先運転に切り替え、この目標温度となるように空気ブロア２６を制御する。このとき、燃料利用率設定手段６４は、第１燃料利用率（例えば、７８％）を設定し、制御手段６０は、この第１燃料利用率となるように燃料ガスブロア１６を制御する。 In step S34, the control means 60 switches to the temperature priority operation in which the temperature of the cell stack 6 is controlled to be the target temperature (for example, 750 ° C.), and controls the air blower 26 so as to be the target temperature. At this time, the fuel utilization rate setting means 64 sets the first fuel utilization rate (for example, 78%), and the control means 60 controls the fuel gas blower 16 so as to be the first fuel utilization rate.

そして、このような第１温度優先運転が第２所定時間（例えば、２時間）継続して行われ、この運転状態が安定すると、ステップＳ３５からステップＳ３６に進み、このときの空気流量が計測され、空気利用率演算手段７６は、この計測された空気流量に基づいて第２空気利用率を演算し（ステップＳ３８）、この第２空気利用率がメモリ手段７２Ｂに記憶される。 Then, such a first temperature priority operation is continuously performed for a second predetermined time (for example, 2 hours), and when this operating state becomes stable, the process proceeds from step S35 to step S36, and the air flow rate at this time is measured. The air utilization rate calculation means 76 calculates the second air utilization rate based on the measured air flow rate (step S38), and the second air utilization rate is stored in the memory means 72B.

このように第１温度優先運転における空気流量に基づいて第２空気利用率が演算されると、ステップＳ３８に進み、コントローラ５２Ｂは第２温度優先運転を設定する。この第２温度優先運転においては、燃料利用率設定手段６４は、第１燃料利用率（例えば、７８％）よりも高い第２燃料利用率（例えば、８０％）を設定し，制御手段６０はこの第２燃料利用率となるように燃料ガスブロア１６を制御するとともに、セルスタック６の温度（温度検知手段５４の検知温度）が目標温度となるように空気ブロア２６を制御する。 When the second air utilization rate is calculated based on the air flow rate in the first temperature priority operation in this way, the process proceeds to step S38, and the controller 52B sets the second temperature priority operation. In this second temperature priority operation, the fuel utilization rate setting means 64 sets a second fuel utilization rate (for example, 80%) higher than the first fuel utilization rate (for example, 78%), and the control means 60 sets the second fuel utilization rate (for example, 80%). The fuel gas blower 16 is controlled so as to have the second fuel utilization rate, and the air blower 26 is controlled so that the temperature of the cell stack 6 (the temperature detected by the temperature detecting means 54) becomes the target temperature.

そして、このような第２温度優先運転が第２所定時間（例えば、２時間）継続して行われ、この運転状態が安定すると、ステップＳ３９からステップＳ４０に進み、このときの空気流量が計測され、空気利用率演算手段７６は、この計測された空気流量に基づいて第３空気利用率を演算し（ステップＳ４１）、この第３空気利用率がメモリ手段７２Ｂに記憶される。尚、この第２温度優先運転が行われる時間は、第２所定時間と異なる第３所定時間（例えば、１時間）行うようにしてもよい。 Then, such a second temperature priority operation is continuously performed for a second predetermined time (for example, 2 hours), and when this operating state becomes stable, the process proceeds from step S39 to step S40, and the air flow rate at this time is measured. The air utilization rate calculation means 76 calculates a third air utilization rate based on the measured air flow rate (step S41), and the third air utilization rate is stored in the memory means 72B. The time during which the second temperature priority operation is performed may be a third predetermined time (for example, 1 hour) different from the second predetermined time.

このように第２温度優先運転における第３空気利用率が演算されると、空気利用率差演算手段８４は、第１温度優先運転における第２空気利用率と第２温度優先運転における第３空気利用率との空気利用率差を演算し、この演算空気利用率差に基づいて燃料ガス流量計測手段１７の検知誤差の有無の判定が行われる。 When the third air utilization rate in the second temperature priority operation is calculated in this way, the air utilization rate difference calculation means 84 uses the second air utilization rate in the first temperature priority operation and the third air in the second temperature priority operation. The air utilization rate difference from the utilization rate is calculated, and the presence or absence of a detection error of the fuel gas flow rate measuring means 17 is determined based on the calculated air utilization rate difference.

第１温度優先運転から第２温度優先運転に切り替えると、燃料利用率については第２燃料利用率に上昇するので、セルスタック６で発電に寄与する燃料ガスの消費量が多くなり、従って、セルスタック６の下流側の燃焼空間で燃料される燃料ガスが少なくなってセルスタック６の温度は低下傾向になるが、温度優先運転を行っているために、セルスタック６の温度低下を抑えるように空気（酸化材ガス）の供給流量が少なくなる。 When switching from the first temperature priority operation to the second temperature priority operation, the fuel utilization rate rises to the second fuel utilization rate, so that the consumption of fuel gas that contributes to power generation in the cell stack 6 increases, and therefore the cell. The fuel gas fueled in the combustion space on the downstream side of the stack 6 decreases, and the temperature of the cell stack 6 tends to decrease. However, since the temperature priority operation is performed, the temperature decrease of the cell stack 6 should be suppressed. The supply flow rate of air (oxidant gas) is reduced.

このとき、燃料ガス流量計測手段１７の検知誤差は、第１及び第２温度優先運転における空気利用率差にも現れ、この第３の実施形態では、かかる空気利用率差（演算空気利用率差）に着目して燃料ガス流量計測手段１７の検知誤差をチェックしている。即ち、燃料ガス流量計測手段１７に検知誤差がない場合、第１温度優先運転における第２空気利用率は例えば４０％程度となり、また燃料利用率を第２燃料利用率に上昇させた第２温度優先運転における第３空気利用率は例えば４６％程度となり、空気利用率差（演算空気利用率差）は例えば６ポイントとなる。一方、燃料ガス流量計測手段１７に検知誤差、特にプラス側の誤差が存在する場合、この空気利用率差は、検知誤差がない場合に比して小さく、６ポイントよりも小さくなる。 At this time, the detection error of the fuel gas flow rate measuring means 17 also appears in the difference in air utilization rate in the first and second temperature priority operations, and in the third embodiment, the difference in air utilization rate (calculated air utilization rate difference). ), And the detection error of the fuel gas flow rate measuring means 17 is checked. That is, when there is no detection error in the fuel gas flow rate measuring means 17, the second air utilization rate in the first temperature priority operation is, for example, about 40%, and the second temperature in which the fuel utilization rate is increased to the second fuel utilization rate. The third air utilization rate in the priority operation is, for example, about 46%, and the air utilization rate difference (calculated air utilization rate difference) is, for example, 6 points. On the other hand, when the fuel gas flow rate measuring means 17 has a detection error, particularly an error on the plus side, this air utilization rate difference is smaller than that when there is no detection error, and is smaller than 6 points.

更に説明すると、第１温度優先運転から第２温度優先運転に切り換えた際に燃料ガス流量計測手段１７に検知誤差、特にプラス側の誤差が存在していると、燃料ガスがより多く流れるために温度の低下幅は小さくなり、従って、このときに絞る空気量も少なくてよく、空気利用率差は測定誤差のない場合に比して小さく、例えば、燃料ガス流量計測手段１７においてプラス側に例えば２％の検知誤差が存在していると、この第３空気利用率は４１．５％程度となる。 Further explaining, if there is a detection error in the fuel gas flow rate measuring means 17 when switching from the first temperature priority operation to the second temperature priority operation, particularly an error on the positive side, more fuel gas flows. Therefore, the amount of air squeezed at this time is small, and the difference in air utilization rate is smaller than when there is no measurement error. For example, in the fuel gas flow rate measuring means 17, the positive side is, for example. If there is a detection error of 2%, this third air utilization rate will be about 41.5%.

このようなことから、第２空気利用率と第３空気利用率との空気利用率差が演算された後は、ステップＳ４３においてこの空気利用率差（演算空気利用率差）が基準空気利用率差よりも小さいかが判断される。基準空気利用率としては、例えば、検知誤差がない場合における空気利用率差の例えば６ポイント程度に設定される。 Therefore, after the air utilization rate difference between the second air utilization rate and the third air utilization rate is calculated, this air utilization rate difference (calculated air utilization rate difference) becomes the reference air utilization rate in step S43. It is judged whether it is smaller than the difference. The reference air utilization rate is set to, for example, about 6 points of the air utilization rate difference when there is no detection error.

この場合、流量誤差判定手段６８Ｂは、この空気利用率差（演算空気利用率差）と基準空気利用率差（例えば、６ポイント）とを対比し、この空気利用率差が基準空気利用率差よりも小さいときには燃料ガス流量計測手段１７の計測値と実際の燃料ガスの流量との間にプラス側の乖離があり、このような場合、流量誤差判定手段６８Ｂは、燃料ガス流量計測手段１７にプラス側の誤差ありと判定する（ステップＳ４４）。 In this case, the flow rate error determining means 68B compares the air utilization rate difference (calculated air utilization rate difference) with the reference air utilization rate difference (for example, 6 points), and this air utilization rate difference is the reference air utilization rate difference. When it is smaller than, there is a positive deviation between the measured value of the fuel gas flow rate measuring means 17 and the actual flow rate of the fuel gas. In such a case, the flow rate error determining means 68B uses the fuel gas flow rate measuring means 17 It is determined that there is an error on the plus side (step S44).

流量誤差判定手段６８Ｂがかく判定すると、燃料利用率設定手段６４は燃料利用率として第３燃料利用率（例えば、８２％）を設定し（ステップＳ４５）、このように燃料ガス流量計測手段１７のプラス側の測定誤差により燃料利用率を第３燃料利用率に上昇させることにより、燃料供給不足などが生じることなく発電効率をより高めることができる。尚、この空気利用率差が基準空気利用率差以上であると、燃料ガス流量計測手段１７に検知誤差が存在しないか、或いは存在していてもマイナス側の検知誤差（換言すると、不足側の誤差）であるために、燃料利用率はそのまま維持される。 When the flow rate error determining means 68B determines in this way, the fuel utilization rate setting means 64 sets the third fuel utilization rate (for example, 82%) as the fuel utilization rate (step S45), and thus the fuel gas flow rate measuring means 17 By increasing the fuel utilization rate to the third fuel utilization rate due to the measurement error on the positive side, it is possible to further improve the power generation efficiency without causing a fuel supply shortage or the like. If the air utilization rate difference is equal to or greater than the reference air utilization rate difference, the fuel gas flow rate measuring means 17 does not have a detection error, or even if it exists, a negative detection error (in other words, a shortage side). Since it is an error), the fuel utilization rate is maintained as it is.

この第３の実施形態においても、第２の実施形態と略同様に、燃料ガス流量計測手段１７のプラス側の測定誤差に応じて、上昇利用率を演算して第３燃料利用率を設定するようにしてもよく、この場合においても、コントローラ５２Ｂに上昇利用率演算手段（図示せず）を含めることができる。 Also in this third embodiment, similarly to the second embodiment, the ascending utilization rate is calculated and the third fuel utilization rate is set according to the measurement error on the plus side of the fuel gas flow rate measuring means 17. In this case as well, the controller 52B can include an ascending utilization rate calculation means (not shown).

この上昇利用率演算手段は、第１及び第２温度優先運転における空気利用率差（演算空気利用率差）と基準空気利用率差との空気利用率差、即ち比較空気利用率差（比較酸化材利用率差）を演算し、この比較空気利用率差の値に基づいて上昇利用率を演算するようにすることができる。 This increased utilization rate calculation means is an air utilization rate difference between the air utilization rate difference (calculated air utilization rate difference) and the reference air utilization rate difference in the first and second temperature priority operations, that is, the comparative air utilization rate difference (comparative oxidation). The material utilization rate difference) can be calculated, and the increase utilization rate can be calculated based on the value of this comparative air utilization rate difference.

この場合、上昇利用率演算手段による上昇利用率は、例えば、式（４）、
上昇利用率＝α×比較空気利用率差
を用いて演算することができる。ここで、αは係数であって、この係数αは、実験的に導き出される値である。 In this case, the increase utilization rate by the increase utilization rate calculation means is, for example, the equation (4),
It can be calculated using the rising utilization rate = α × comparative air utilization rate difference. Here, α is a coefficient, and this coefficient α is a value derived experimentally.

例えば、基準空気利用率差が６ポイントであるときに、この演算空気利用率差が１．５ポイントであると、この基準空気利用率差と演算空気利用率差との比較空気利用率差は４．５ポイントとなり、上昇利用率演算手段は、上記式（４）を用い、係数（例えば、０．３５）にこの比較空気利用率差の４．５を積算して例えば１．６ポイントを算出し、第３燃料利用率として第２燃料利用率（例えば、８０％）にこの上昇利用率（例えば、１．６％）を加算した８１．６％が設定される。 For example, when the reference air utilization rate difference is 6 points and the calculated air utilization rate difference is 1.5 points, the comparison air utilization rate difference between the reference air utilization rate difference and the calculated air utilization rate difference is It becomes 4.5 points, and the rising utilization rate calculation means uses the above equation (4) and adds 4.5 of this comparative air utilization rate difference to the coefficient (for example, 0.35) to obtain 1.6 points, for example. 81.6% is set as the third fuel utilization rate, which is calculated by adding the increased utilization rate (for example, 1.6%) to the second fuel utilization rate (for example, 80%).

以上、本発明に従う固体酸化物形燃料電池システムの各種実施形態について説明したが、本発明はこれら実施形態に限定されるものではなく、本発明の範囲を逸脱することなく種々の修正乃至変更が可能である。 Although various embodiments of the solid oxide fuel cell system according to the present invention have been described above, the present invention is not limited to these embodiments, and various modifications or changes can be made without departing from the scope of the present invention. It is possible.

本願発明の効果を確認するために、次の通りのシミュレーションを行った。まず、第１の実施形態の固体酸化物形燃料電池システムの制御系によるシミュレーションを行い、このシミュレーションにおいて定格出力７００Ｗのセルスタックを用いたシステムを想定した。利用率値優先運転において第１燃料利用率を７８％、第１空気利用率を３８％に設定し、燃料ガス流量計測手段の測定誤差として、測定誤差なし、プラス側２％この測定誤差あり、プラス側３％の測定誤差ありについてシミュレーションを行った。 In order to confirm the effect of the present invention, the following simulation was performed. First, a simulation was performed by the control system of the solid oxide fuel cell system of the first embodiment, and a system using a cell stack having a rated output of 700 W was assumed in this simulation. In the utilization rate value priority operation, the first fuel utilization rate is set to 78% and the first air utilization rate is set to 38%, and the measurement error of the fuel gas flow rate measuring means is no measurement error, plus side 2%. A simulation was performed for a measurement error of 3% on the plus side.

このシミュレーション結果は、表１に示す通りであった。表１に示す結果から理解されるように、第１燃料利用率（７８％）から第２燃料利用率（８０％）に上昇させたときには、セルスタックの温度は低下するが、その低下傾向は測定誤差が大ききほど小さくなった（尚、測定誤差プラス３％の場合、温度差は上昇している）。そして、このプラス側の測定誤差の大きさに応じて第３燃料利用率を設定し、プラス側２％の測定誤差の場合に第３燃料利用率を８１．６％に、またプラス側３％の測定誤差の場合に第３燃料利用率を８２．４％に設定して発電運転したときの発電効率を演算したところいずれも５３．５％であり、第１燃料利用率で運転したときよりも１．１ポイント改善されることがわかった。 The results of this simulation are as shown in Table 1. As can be seen from the results shown in Table 1, when the temperature of the cell stack is increased from the first fuel utilization rate (78%) to the second fuel utilization rate (80%), the temperature of the cell stack decreases, but the decreasing tendency is The larger the measurement error, the smaller it became (note that the temperature difference increased when the measurement error was plus 3%). Then, the third fuel utilization rate is set according to the magnitude of the measurement error on the plus side, and in the case of a measurement error of 2% on the plus side, the third fuel utilization rate is set to 81.6% and 3% on the plus side. In the case of the measurement error of, when the third fuel utilization rate was set to 82.4% and the power generation efficiency was calculated, it was 53.5%, which is higher than when the first fuel utilization rate was used. Was also found to be improved by 1.1 points.

次いで、第２の実施形態の固体酸化物形燃料電池システムの制御系によるシミュレーションを、上述したと同様の条件で行った。利用率値優先運転において第１燃料利用率を７８％、第１空気利用率を３８％に設定し、温度優先運転において第２燃料利用率を８０％に設定し、燃料ガス流量計測手段の測定誤差として、測定誤差なし、プラス側２％この測定誤差ありについてシミュレーションを行った。

Next, a simulation by the control system of the solid oxide fuel cell system of the second embodiment was performed under the same conditions as described above. The first fuel utilization rate is set to 78% and the first air utilization rate is set to 38% in the utilization rate priority operation, the second fuel utilization rate is set to 80% in the temperature priority operation, and the measurement of the fuel gas flow rate measuring means is performed. As an error, a simulation was performed with no measurement error and 2% on the plus side with this measurement error.

このシミュレーション結果は、表２に示す通りであった。表２に示す結果から理解されるように、利用率値優先運転から温度優先運転に切り替えたときには、空気利用率は上昇するが、プラス側２％の測定誤差の場合には４１．５％までしか上昇せず、この上昇に基づき第３燃料利用率を８２％に設定して発電運転したときの発電効率を演算したところ５３．８％であり、第１燃料利用率で運転したときよりも１．４ポイント改善されることがわかった。 The results of this simulation are as shown in Table 2. As can be understood from the results shown in Table 2, the air utilization rate increases when the utilization rate value priority operation is switched to the temperature priority operation, but up to 41.5% in the case of a measurement error of 2% on the plus side. However, based on this increase, the power generation efficiency when the third fuel utilization rate was set to 82% and the power generation operation was calculated was 53.8%, which was higher than when the first fuel utilization rate was operated. It was found to be improved by 1.4 points.

次に、第３の実施形態の固体酸化物形燃料電池システムの制御系によるシミュレーションを、上述したと同様の条件で行った。利用率値優先運転において第１燃料利用率を７８％、第１空気利用率を３８％に設定し、その後利用率値優先運転から第１温度優先運転に切り替え、この第１温度優先運転において第１燃料利用率を７８％に設定し、その後、第１温度優先運転から第２温度優先運転に切り替え、第２燃料利用率を８０％に設定し、測定誤差なし、プラス側２％この測定誤差ありについてシミュレーションを行った。

Next, a simulation by the control system of the solid oxide fuel cell system of the third embodiment was performed under the same conditions as described above. In the utilization rate value priority operation, the first fuel utilization rate is set to 78%, the first air utilization rate is set to 38%, and then the utilization rate value priority operation is switched to the first temperature priority operation, and in this first temperature priority operation, the first 1 Set the fuel utilization rate to 78%, then switch from the 1st temperature priority operation to the 2nd temperature priority operation, set the 2nd fuel utilization rate to 80%, no measurement error, plus side 2% This measurement error A simulation was performed for the presence.

このシミュレーション結果は、表３に示す通りであった。表３に示す結果から理解されるように、第１温度優先運転から第２温度優先運転に切り替えたときには、空気利用率は上昇し、測定誤差がない場合には第３空気利用率は４６％まで上昇するが、プラス側２％の測定誤差の場合には４１．５％までしか上昇せず、このとき第３燃料利用率を８２．４％に設定して発電運転したときの発電効率を演算したところ５３．８％であり、第１燃料利用率で運転したときよりも１．４ポイント改善されることがわかった。 The results of this simulation are as shown in Table 3. As can be understood from the results shown in Table 3, when switching from the first temperature priority operation to the second temperature priority operation, the air utilization rate increases, and if there is no measurement error, the third air utilization rate is 46%. However, in the case of a measurement error of 2% on the plus side, it only rises to 41.5%, and at this time, the power generation efficiency when the third fuel utilization rate is set to 82.4% and power generation operation is performed. It was calculated to be 53.8%, which was found to be 1.4 points better than when operating at the first fuel utilization rate.

比較のために、従来の条件のシミュレーションも行った。燃料ガス流量測定手段の測定誤差なしの場合は、燃料利用率を７８％及び８０％に設定し、この測定誤差プラス側２％の場合は、燃料利用率を８０％に設定し、またその測定誤差がプラス側３％の場合には、燃料利用率を８０％に設定して行った。

For comparison, a simulation of conventional conditions was also performed. If there is no measurement error of the fuel gas flow rate measuring means, the fuel utilization rate is set to 78% and 80%, and if this measurement error is 2% on the plus side, the fuel utilization rate is set to 80% and its measurement. When the error was 3% on the plus side, the fuel utilization rate was set to 80%.

このシミュレーション結果は、表４に示す通りであり、測定誤差がプラス側にあるときには、測定誤差なしの場合に比して発電効率が低いことがわかった。 The results of this simulation are as shown in Table 4, and it was found that when the measurement error is on the plus side, the power generation efficiency is lower than when there is no measurement error.

２固体酸化物形燃料電池システム
６セルスタック
１６燃料ガスブロア
１７燃料ガス流量計測手段
２６空気ブロア（酸化材ガスブロア）
２７空気流量計測手段（酸化材ガス流量計測手段）
５２，５２Ａ，５２Ｂコントローラ
６２温度差演算手段
６４燃料利用率設定手段
６６空気利用率設定手段（酸化材利用率設定手段）
６８，６８Ａ，６８Ｂ流量誤差判定手段
７６空気利用率演算手段
８４空気利用率差演算手段（酸化材利用率差演算手段）

2 Solid oxide fuel cell system 6 Cell stack 16 Fuel gas blower 17 Fuel gas flow rate measuring means 26 Air blower (oxidant gas blower)
27 Air flow rate measuring means (oxidant gas flow rate measuring means)
52, 52A, 52B controller 62 Temperature difference calculation means 64 Fuel utilization rate setting means 66 Air utilization rate setting means (oxidant utilization rate setting means)
68, 68A, 68B Flow rate error determination means 76 Air utilization rate calculation means 84 Air utilization rate difference calculation means (oxidant utilization rate difference calculation means)

Claims

A cell stack in which solid oxide fuel cell cells that generate power by reacting a fuel gas and an oxide gas are laminated, and an oxide gas supply means for supplying the oxide gas to the oxygen electrode side of the cell stack. To measure the flow rate of the fuel gas supply means for supplying the fuel gas to the fuel electrode side of the cell stack and the fuel gas supplied from the fuel gas supply means to the fuel electrode side of the cell stack. A solid oxide fuel cell comprising a fuel gas flow rate measuring means, a temperature detecting means for detecting the temperature of the cell stack, and a controller for operating and controlling the fuel gas supply means and the oxide gas supply means. It ’s a fuel cell system,
The controller sets the fuel utilization rate setting means for setting the utilization rate of the fuel gas consumed in the power generation in the cell stack, and the utilization rate of the oxide gas consumed in the power generation in the cell stack. The oxide material utilization rate setting means for the purpose and the flow rate error determining means for determining the presence or absence of the detection error of the fuel gas flow rate measuring means are included.
In the rated power generation state of the cell stack, the controller performs a utilization rate value priority operation that prioritizes the fuel utilization rate and the oxide material utilization rate, and in the utilization rate value priority operation, the fuel utilization rate setting means is the first. While setting the fuel utilization rate, the oxide utilization rate setting means sets the first oxide utilization rate, and then the controller performs a utilization rate increase operation in which the fuel utilization rate is increased, and the utilization rate is increased. In operation, the oxide utilization rate setting means maintains the first oxide utilization rate, and the fuel utilization rate setting means sets a second fuel utilization rate higher than the first fuel utilization rate. The temperature detecting means detects the first temperature state of the cell stack in the utilization rate value priority operation and the second temperature state of the cell stack in the utilization rate increasing operation, and the flow rate error determining means of the cell stack A solid oxide fuel cell system characterized in that the presence or absence of a detection error of the fuel gas flow rate measuring means is determined based on the first detection temperature in the first temperature state and the second detection temperature in the second temperature state. ..

The flow rate error determining means compares the calculated temperature difference between the first detected temperature and the second detected temperature of the temperature detecting means with the reference temperature difference, and when the calculated temperature difference is smaller than the reference temperature difference. The first aspect of claim 1 is characterized in that the fuel gas flow rate measuring means is determined to have a positive side error, and the fuel utilization rate setting means sets a third fuel utilization rate higher than the second fuel utilization rate. The solid oxide fuel cell system described.

The controller is an increase utilization rate calculation means for calculating an increase utilization rate further increased from the second fuel utilization rate when the flow rate error determining means determines that the fuel gas flow rate measuring means has a positive side error. The rising utilization rate calculating means calculates the rising utilization rate based on the comparative temperature difference between the calculated temperature difference and the reference temperature difference, and the fuel utilization rate setting means is the second fuel utilization rate. The solid oxide fuel cell system according to claim 2, wherein the third fuel utilization rate is set by adding the increase utilization rate to the above.

A cell stack in which solid oxide fuel cell cells that generate power by reacting a fuel gas and an oxide gas are laminated, and an oxide gas supply means for supplying the oxide gas to the oxygen electrode side of the cell stack. To measure the flow rate of the fuel gas supply means for supplying the fuel gas to the fuel electrode side of the cell stack and the fuel gas supplied from the fuel gas supply means to the fuel electrode side of the cell stack. The fuel gas flow rate measuring means, the oxide gas flow rate measuring means for measuring the flow rate of the oxide gas supplied from the oxide gas supply means to the oxygen electrode side of the cell stack, and the temperature of the cell stack are measured. A solid oxide fuel cell system comprising a temperature detecting means for detecting, a fuel gas supply means, and a controller for operating and controlling the fuel gas supply means and the oxide gas supply means.
The controller sets the fuel utilization rate setting means for setting the utilization rate of the fuel gas consumed in the power generation in the cell stack, and the utilization rate of the oxide gas consumed in the power generation in the cell stack. The oxide material utilization rate setting means for the purpose and the flow rate error determining means for determining the presence or absence of the detection error of the fuel gas flow rate measuring means are included.
In the rated power generation state of the cell stack, the controller performs a utilization rate value priority operation that prioritizes the fuel utilization rate and the oxide material utilization rate, and in the utilization rate value priority operation, the fuel utilization rate setting means is the first. The fuel utilization rate is set, the oxide utilization rate setting means sets the first oxide utilization rate, and then the controller performs a temperature priority operation so that the detection temperature of the temperature detection means becomes the target temperature. In the temperature priority operation, the fuel utilization rate setting means sets a second fuel utilization rate higher than the first fuel utilization rate, and the oxide gas supply means sets the detection temperature of the temperature detection means. Is controlled to be the target temperature, and then the flow error determining means determines whether or not there is a detection error of the fuel gas flow measuring means based on the second oxide utilization rate in the temperature priority operation. Characterized solid oxide fuel cell system.

The controller includes an oxide material utilization rate calculation means for calculating the oxide material utilization rate, and the oxide material utilization rate calculation means is based on the supply flow rate of the oxide material gas in the temperature priority operation. The utilization rate is calculated, and the flow error determination means compares the second oxide utilization rate and the reference oxide utilization rate in the temperature priority operation, and the second oxide utilization rate is the reference oxide utilization rate. When it is smaller than, it is determined that the fuel gas flow rate measuring means has a positive side error, and the fuel utilization rate setting means sets a third fuel utilization rate higher than the second fuel utilization rate. The solid oxide fuel cell system according to claim 4.

The controller includes an ascending utilization rate calculating means for calculating an ascending utilization rate further increased from the second fuel utilization rate when the flow rate error determining means determines that there is a positive side error, and the ascending utilization rate. The calculation means calculates the increase utilization rate based on the difference in the comparison oxide utilization rate between the second oxide utilization rate and the reference oxide utilization rate, and the fuel utilization rate setting means is the second fuel utilization rate. The solid oxide fuel cell system according to claim 5, wherein the third fuel utilization rate is set by adding the increased utilization rate to the above.

A cell stack in which solid oxide fuel cell cells that generate power by reacting a fuel gas and an oxide gas are laminated, and an oxide gas supply means for supplying the oxide gas to the oxygen electrode side of the cell stack. To measure the flow rate of the fuel gas supply means for supplying the fuel gas to the fuel electrode side of the cell stack and the fuel gas supplied from the fuel gas supply means to the fuel electrode side of the cell stack. The fuel gas flow rate measuring means, the oxide gas flow rate measuring means for measuring the flow rate of the oxide gas supplied from the oxide gas supply means to the oxygen electrode side of the cell stack, and the temperature of the cell stack are measured. A solid oxide fuel cell system comprising a temperature detecting means for detecting, a fuel gas supply means, and a controller for operating and controlling the fuel gas supply means and the oxide gas supply means.
The controller sets the fuel utilization rate setting means for setting the utilization rate of the fuel gas consumed in the power generation in the cell stack, and the utilization rate of the oxide gas consumed in the power generation in the cell stack. The oxide material utilization rate setting means for the purpose and the flow rate error determining means for determining the presence or absence of the detection error of the fuel gas flow rate measuring means are included.
In the rated power generation state of the cell stack, the controller performs a utilization rate value priority operation that prioritizes the fuel utilization rate and the oxide material utilization rate, and in the utilization rate value priority operation, the fuel utilization rate setting means is the first. While setting the fuel utilization rate, the oxide utilization rate setting means sets the first oxide utilization rate, and then the controller gives priority to the first temperature so that the detection temperature of the temperature detection means becomes the target temperature. In the first temperature priority operation, the fuel utilization rate setting means sets the first fuel utilization rate, and the oxide gas supply means sets the detection temperature of the temperature detecting means to the target temperature. After that, the controller performs a second temperature priority operation, and in the second temperature priority operation, the fuel utilization rate setting means uses a second fuel higher than the first fuel utilization rate. While setting the rate, the oxide gas supply means is controlled so that the detection temperature of the temperature detection means becomes the target temperature, and the flow error determination means is the second oxide material in the first temperature priority operation. A solid oxide fuel cell system characterized in that the presence or absence of a detection error of the fuel gas flow rate measuring means is determined based on the utilization rate and the utilization rate of the third oxide material in the second temperature priority operation.

The controller includes an oxide material utilization rate calculation means for calculating the oxide material utilization rate, and the oxide material utilization rate calculation means is based on the supply flow rate of the oxide material gas in the first temperature priority operation. The oxide material utilization rate is calculated, and the third oxide material utilization rate is calculated based on the supply flow rate of the oxide material gas in the second temperature priority operation. The flow rate error determining means is the second oxide material utilization rate. And the calculated oxide utilization rate difference of the third oxide material utilization rate and the reference oxide utilization rate difference are compared, and when the calculated oxide utilization rate difference is smaller than the reference oxide utilization rate difference, the fuel gas The solid according to claim 7, wherein the flow rate measuring means is determined to have a positive side error, and the fuel utilization rate setting means sets a third fuel utilization rate higher than the second fuel utilization rate. Oxidized fuel cell system.

The controller is an increase utilization rate calculation means for calculating an increase utilization rate further increased from the second fuel utilization rate when the flow rate error determining means determines that the fuel gas flow rate measuring means has a positive side error. The increase utilization rate calculation means calculates the increase utilization rate based on the comparison oxide utilization rate difference between the calculated oxide utilization rate difference and the reference oxide utilization rate difference, and sets the fuel utilization rate. The solid oxide fuel cell system according to claim 8, wherein the means is to set the third fuel utilization rate by adding the increase utilization rate to the second fuel utilization rate.