JP6223802B2 - Control device for combined power generation system, combined power generation system including the same, and control method for combined power generation system - Google Patents

Description

  The present invention relates to a combined power generation system control device, a combined power generation system including the same, and a combined power generation system control method.

  A fuel cell is a power generation device that uses a power generation method based on an electrochemical reaction. A fuel electrode that is an electrode on the fuel side, an air electrode that is an electrode on the air (oxidant) side, and only ions between them. Various types of electrolytes have been developed depending on the type of electrolyte.

  Among these, for example, a solid oxide fuel cell (hereinafter referred to as “SOFC”) uses ceramics such as zirconia ceramics as an electrolyte, and city gas, natural gas, petroleum, methanol, coal gasification is used. This is a fuel cell operated using gas or the like as fuel. This SOFC is known as a high-efficiency high-temperature fuel cell having an operating temperature as high as about 700 to 1000 ° C. in order to increase ionic conductivity.

  The SOFC is a space in which a power stack composed of a fuel electrode, an electrolyte, and an air electrode is electrically connected via an interconnector, and a plurality of cell stacks are partitioned at least partially around the periphery. It is installed in the power generation room. In addition, since the operating temperature of this SOFC is increased in order to increase the ionic conductivity, the discharge air discharged from the compressor of the gas turbine and heated to high temperature using the exhaust gas heat of the gas turbine is converted to the air electrode side. Can be used as air (oxidant) supplied to Moreover, the compatibility with a gas turbine is good, for example, high-temperature exhaust fuel gas that could not be used in SOFC can be used as a fuel for a combustor of a gas turbine.

  In order to raise the temperature of the cell stack to the rated power generation temperature at the start-up of such SOFC, the temperature of the power generation chamber is increased by supply air (hereinafter referred to as “first temperature control”), and fuel is supplied to the power generation chamber and burned in the power generation chamber. The temperature is raised by (combustion in the furnace) (hereinafter referred to as “second temperature control”), and a technique for raising the temperature of the SOFC in a short time has been proposed.

In the following Patent Document 1, in a hybrid power generation apparatus including a fuel cell and a gas turbine, a start-up method in which the temperature of the fuel cell reaches a predetermined temperature by raising the temperature of the power generation chamber of the fuel cell with hot air from the compressor of the gas turbine. Is disclosed.
Further, in Patent Document 2 below, when the temperature is raised, the flow rate of air flowing through the high-temperature heat exchanger and the low-temperature heat exchanger is adjusted when being sent from the compressor of the gas turbine to the fuel cell via the heat exchanger. Thus, a technique for adjusting the temperature of air sent to the fuel cell is disclosed.

JP 2009-187756 A International Publication No. 2010/088883

  By the way, in the combined power generation system, when the temperature of the power generation chamber is increased by switching to the temperature increase using combustion in the power generation chamber of the fuel cell after the temperature increase by the compressed air supplied from the internal combustion engine, When the supply air flow rate is large or the supply air temperature from the internal combustion engine is lower than the temperature in the power generation chamber, the temperature in the furnace is cooled because the combustion field in the furnace of the fuel cell is cooled. On the other hand, if the supply air temperature supplied to the power generation chamber is too higher than the temperature in the power generation chamber, combustion at the lower portion of the power generation chamber, which is the inlet of the fuel cell air, increases and the temperature rises locally. is there. For this reason, in the temperature rise control of the fuel cell, it is a problem to optimize the switching timing of the temperature rise control in accordance with the state of the internal combustion engine and the fuel cell, and suppress heat loss and time loss.

  However, Patent Document 1 does not disclose adjusting the flow rate of hot air used to raise the temperature of the fuel cell, and supplying the fuel for combustion to the fuel cell to raise the temperature. Also in Patent Document 2, in a system for raising the temperature of air pressurized by a compressor using exhaust gas from a gas turbine, air is supplied to the fuel cell via a high temperature side heat exchanger and a low temperature side heat exchanger. Although it is described that the temperature rise is optimized by controlling the flow rate of air supplied to the gas turbine combustor and the fuel cell at the time of supply, the temperature rise control timing using combustion in the furnace is disclosed. It has not been.

  The present invention has been made to solve the above problems, and is a control device for a combined power generation system capable of suppressing heat loss and time loss in temperature rise control of a power generation chamber of a fuel cell, a combined power generation system including the same, and a combined power generation system including the same An object is to provide a method for controlling a power generation system.

In order to solve the above problems, the present invention employs the following means.
The present invention is a control device for a combined power generation system that generates power by combining a fuel cell and an internal combustion engine, wherein the internal combustion engine burns fuel discharged from the fuel cell, and is supplied from the combustor. A gas turbine driven by the generated combustion gas, a compressor for compressing air, heat exchange means for heating the air compressed by the compressor, and the fuel heated by the heat exchange means for the fuel A power generation chamber of the fuel cell, comprising: a first bypass path that bypasses the air to the combustor from a path that circulates the battery; and a control valve that adjusts a flow rate of the air that is circulated to the first bypass path. temperature, when it becomes within combustible first predetermined temperature or a furnace while supplying the fuel to the furnace combustion to the fuel cell, in accordance with the temperature of the power generation chamber, the control valve And adjusting the opening and to provide a control apparatus of the combined cycle power generation system which adjusts the output of the internal combustion engine.

According to the present invention, the air compressed by the compressor of the gas turbine is heated by the heat exchanging means, discharged from the outlet of the heat exchanging means, and supplied to the fuel cell, and from above the supply path to the fuel cell. Since it is divided into the air flowing through the first bypass path to be bypassed by the combustor, when the control valve is adjusted in the opening direction, the flow rate of air supplied to the fuel cell is made smaller than before the adjustment. Further, when the output of the internal combustion engine is controlled to decrease, the temperature of the air supplied to the fuel cell is made lower than when the output of the internal combustion engine is not decreased. Therefore, when the temperature of the power generation chamber of the fuel cell becomes equal to or higher than the first predetermined temperature at which combustion in the furnace is possible , fuel is supplied to the fuel cell and combustion in the furnace is performed. Since the temperature of the air supplied to the fuel cell is adjusted to be low, cooling of the in-furnace combustion field of the fuel cell or local temperature rise of the power generation chamber can be prevented in the second temperature rise control. .

  In a combined power generation system including a fuel cell and an internal combustion engine, when the fuel cell is started, a two-step temperature increase control of a first temperature increase control and a second temperature increase control is performed. In the temperature rise control, the flow rate of air supplied to the fuel cell is adjusted in accordance with the temperature of the power generation chamber of the fuel cell. Since the temperature of the air supplied to the fuel cell is adjusted according to the temperature of the power generation chamber of the fuel cell, air is supplied to the power generation chamber due to the high temperature of the supply air in the second temperature rise control. It is possible to prevent the temperature from excessively increasing due to increased combustion in the portion (near the air inlet). In addition, since the power generation chamber heated by the first temperature increase control can be prevented from being lowered, it is possible to efficiently switch from the first temperature increase control to the second temperature increase control when the power generation chamber is heated. The heat loss and time loss can be minimized, and the time required for starting the fuel cell can be shortened accordingly.

In the control device of the combined power generation system, it is preferable that the supply amount of the fuel supplied to the fuel cell is adjusted so as to follow a predetermined temperature increase rate of the power generation chamber.
Thereby, the temperature distribution in the power generation chamber can be optimized.

  In the control device of the combined power generation system, the supply of the fuel to be supplied to the fuel cell when the temperature of the power generation chamber of the fuel cell is equal to or higher than a first predetermined temperature and the temperature distribution in the power generation chamber exceeds an allowable value. It is preferable to reduce the amount or to stop the supply of the fuel.

  By reducing the amount of fuel supplied to the fuel cell or stopping the fuel supply, it is possible to suppress the temperature distribution in the power generation chamber from becoming larger than the allowable value. The temperature distribution in the power generation chamber indicates, for example, a distribution state of temperatures detected in the upper, central, and lower regions when the power generation chamber is divided into three regions in the vertical direction.

  The control device of the combined power generation system includes: a second bypass path that bypasses the air compressed by the compressor to an outlet of the heat exchange means without passing through the heat exchange means; and a second bypass path that discharges the air. It is good also as providing the bypass valve which adjusts the flow volume of the said air to distribute | circulate.

  The air compressed by the compressor is air heated in the heat exchange means and air discharged through the second bypass path and bypassed to the outlet of the heat exchange means without passing through the heat exchange means (that is, heat exchange). Therefore, the temperature of the air supplied to the fuel cell can be adjusted by adjusting the bypass valve.

  When the temperature of the power generation chamber of the fuel cell is lower than the first predetermined temperature, the control device for the combined power generation system is configured such that the temperature difference between the metal members constituting the power generation chamber is an allowable temperature distribution in the power generation chamber. It is preferable to control the flow rate and temperature of the air supplied from the internal combustion engine to the fuel cell so as to be equal to or less than the temperature difference.

  By controlling the temperature difference of the metal member constituting the power generation chamber to be equal to or less than the allowable temperature difference of the temperature distribution in the power generation chamber, the stress deformation of the member constituting the power generation chamber can be prevented.

  When the temperature difference between the metal members constituting the power generation chamber is larger than the allowable temperature difference in the temperature distribution in the power generation chamber, the control device of the combined power generation system is configured to control the valve opening degree of the control valve. At least one of the control and the control of the output of the internal combustion engine is temporarily stopped, and the temperature difference of the metal member constituting the power generation chamber becomes equal to or less than the allowable temperature difference of the temperature distribution in the power generation chamber. In this case, it is preferable to resume the control of the valve opening of the control valve and the control of the output of the internal combustion engine.

  When the temperature distribution in the power generation chamber becomes larger than the allowable temperature difference, the spread of the temperature distribution in the power generation chamber can be suppressed by preventing the flow rate or temperature of the supply air from changing.

The control device of the combined power generation system increases the flow rate of the air supplied to the fuel cell so as to follow a predetermined temperature increase rate of the power generation chamber until the temperature of the power generation chamber reaches the first predetermined temperature. It is good as well.
Thereby, the temperature distribution in the power generation chamber can be optimized.

  The power generation chamber of the control device of the combined power generation system is divided into a plurality of regions in the vertical direction, and is divided into an upper part, a central part, and a lower part in order from the top, and when the air is supplied from the lower part, the lower part At least one of the supply amount of the fuel, the supply amount of the air, and the temperature of the air supplied to the fuel cell so that the temperature of the region is lower than the temperature of the upper portion and the central portion. It is good also as adjusting one.

  When air is supplied from the lower part of the power generation chamber, if the temperature in the lower region is high, a lot of combustion proceeds in the lower part, and combustion does not progress in the center or upper part, but the temperature in the lower region becomes low Thus, by reducing the fuel supply amount or the air supply amount, it is possible to prevent the lower portion from being burned first.

  The present invention provides a combined power generation system including a fuel cell, any one of the above control devices, and the internal combustion engine.

The present invention relates to a fuel cell, a combustor that combusts fuel discharged from the fuel cell, a gas turbine that is driven by combustion gas supplied from the combustor, a compressor that compresses air, and compression by the compressor A method of controlling a combined power generation system that generates power in combination with an internal combustion engine having a heat exchange means for heating the heated air, wherein the temperature of the power generation chamber of the fuel cell is a first predetermined value capable of combustion in a furnace A path for supplying the fuel to the fuel cell and causing the air heated in the heat exchange means to flow to the fuel cell in accordance with the temperature of the power generation chamber while supplying fuel to the fuel cell and causing combustion in the furnace A combined power generation system that adjusts a control valve that adjusts the flow rate of the air that flows through a first bypass path that bypasses the air from above to the combustor, and that adjusts the output of the internal combustion engine To provide a control method.

  According to the present invention, there is an effect that heat loss and time loss in temperature increase control of a fuel cell can be suppressed.

It is the figure which showed the whole structure of the combined power generation system which concerns on this invention. It is the schematic of the electric power generation chamber provided in the fuel cell which concerns on this invention. (A) It is a figure for demonstrating the temperature rising control of a power generation chamber. (B) It is the figure which showed an example of the change of the power generation chamber temperature at the time of control based on (a). It is an operation | movement flow of the combined power generation system which concerns on this invention.

  Hereinafter, an embodiment of a control device for a combined power generation system, a combined power generation system including the same, and a control method for the combined power generation system according to the present invention will be described with reference to the drawings.

  A combined power generation system (combined power generation system using a fuel cell and an internal combustion engine) 1 shown in FIG. 1 includes a SOFC 20 that is a high-temperature fuel cell, a gas turbine that is an internal combustion engine, and a micro gas turbine (hereinafter referred to as a gas engine). (Referred to as “MGT”) 10 and a control device 30, and by combining the SOFC 20 and the MGT 10, efficient power generation is performed.

That is, in addition to the SOFC 20 that receives a supply of an oxidizing gas such as air and a fuel gas obtained by reforming city gas (natural gas) and the like, the high temperature discharged from the SOFC 20 after power generation The exhausted fuel and exhausted air are introduced into the combustor, the MGT 10 is operated with the combustion gas, and a generator (not shown) connected to the output shaft of the MGT 10 is driven to generate power.
Furthermore, if high-temperature combustion exhaust gas discharged from the MGT 10 is introduced into the exhaust heat recovery boiler, it is possible to construct a combined power generation system that combines power generation by driving a steam turbine with generated steam.

  Below, the combined power generation system 1 which employ | adopted SOFC20 mentioned above is demonstrated. This SOFC 20 uses ceramics such as zirconia ceramics as an electrolyte and operates (power generation) using city gas, natural gas, petroleum, methanol, coal gasification gas, etc. as fuel, and has an operating temperature to increase ionic conductivity. Is set as high as about 700-1000 degreeC.

  The MGT 10 includes a combustor 14 that combusts fuel discharged from the SOFC 20, a compressor 15 that compresses air, a gas turbine 16 that is driven by combustion gas supplied from the combustor 14, and a first bypass path 17. A control valve 11 provided, a bypass valve 13 provided on the second bypass path 18, and an air heater (heat exchange means) 12 for exchanging heat between the exhaust combustion gas from the gas turbine 16 and the compressed air are provided. Further, the first bypass path 17 bypasses the air supplied from the compressor 15 to the SOFC 20 to the combustor 14 from the oxidizing gas supply line 42. The second bypass path 18 is a path that causes the air discharged from the compressor 15 to bypass without passing through the air heater 12. In the present embodiment, the first bypass path 17 is installed in the package of the MGT 10. However, the present invention is not limited to this and may be provided outside the package of the MGT 10.

  The control valve 11 is provided in the first bypass path 17 and adjusts the flow rate of air flowing through the first bypass path 17. Specifically, the control valve 11 is controlled based on a command acquired from the control device 30, and when the valve opening degree is controlled in the opening direction, the flow rate of air flowing through the first bypass path 17 is increased, and the valve opening is performed. When the degree is controlled in the closing direction, the flow rate of air flowing through the first bypass path 17 is reduced.

  The bypass valve 13 is provided in the second bypass path 18 and adjusts the flow rate of the air flowing through the second bypass path 18. Specifically, the bypass valve 13 is controlled based on a command acquired from the control device 30. When the valve opening degree is controlled in the opening direction, the flow rate of air flowing through the second bypass path 18 is increased, and the valve opening is performed. When the degree is controlled in the closing direction, the flow rate of air flowing through the second bypass path 18 is reduced.

The gas turbine 16 is rotated by the energy of the combustion exhaust gas from the combustor 14 to generate a shaft output, and the compressor 15 and a generator (not shown) are driven using this shaft output. The combustion exhaust gas that has worked in the gas turbine 16 is subjected to heat exchange with compressed air by the air heater 12 and then released to the atmosphere.
The compressor 15 compresses the introduced air (atmosphere), and the drive source in this case is a gas turbine 16. The compressed air compressed by the compressor 15 is supplied to the SOFC or the like via the combustor 14 as combustion air, the air heater 12 as the oxidizing gas, and the oxidizing gas supply line 42.

  The combustor 14 is supplied with compressed air, burns fuel, generates high-temperature and high-pressure combustion exhaust gas, and supplies the combustion exhaust gas to the gas turbine 16. The combustor 14 includes an exhaust fuel gas supply line 27 that supplies exhaust fuel gas from the SOFC 20, a fuel gas supply line 40 that directly supplies unused city gas (fuel gas) without going through the SOFC 20, and an SOFC 20 Are connected to the oxidizing gas discharge passage 43 for supplying the exhausted oxidizing gas supplied to the MGT 10 to the MGT 10 and the first bypass passage 17 that branches from the oxidizing gas supply line 42 and supplies compressed air. ing.

  The combined power generation system 1 is a system that generates power by combining the SOFC 20 and the MGT 10, and includes a fuel supply line 41 that supplies fuel to the fuel electrode of the SOFC 20 and an oxidizing gas supply line 42 that supplies oxidizing gas to the air electrode. ing. The fuel supply line 41 includes a city gas (fuel) supply line 26 having a fuel supply valve (not shown). In FIG. 1, only the fuel supply line 26 is shown as the fuel supply line 41. However, the fuel supply line 41 is not limited to city gas but supplied from a line (not shown). Nitrogen and steam (water) are also included.

  When the combined power generation system 1 is started, the MGT is first started, and after the output of the MGT is stabilized at a certain load, a part of the air (compressed air) supplied from the compressor 15 is supplied to the SOFC 20. Then, pressurize the SOFC20. When the SOFC 20 is pressurized to a predetermined pressure, the SOFC 20 and the MGT 10 are connected, and a transition is made to a combined state in which air is supplied to the combustor 14 of the MGT 10 via the SOFC 20. In the combined state, the fuel gas may be supplied to the combustor 14 via the SOFC 20 as well.

After the transition to the combined state, the air flow rate supplied to the SOFC 20 is increased in order to raise the temperature of the SOFC 20, and the air flow rate supplied to the combustor 14 is reduced by bypassing the SOFC 20. Control is performed so that the entire amount of air is supplied to the combustor 14 via the SOFC 20 after a certain time.
When the temperature of the power generation chamber 50 of the SOFC 20 reaches a certain first predetermined temperature, temperature increase using heat generated by combustion of combustible gas is started inside the power generation chamber 50, and the internal temperature of the power generation chamber 50 is set to a power generation start temperature region. The temperature is raised to a second predetermined temperature. When the SOFC 20 reaches the second predetermined temperature, which is the power generation start temperature, power generation is started, and the temperature is raised to the rated power generation temperature by using heat generation using self-heat generation by power generation and heating by furnace combustion.
As described above, the SOFC 20 reaches the target temperature through a process of temperature rise by air, temperature rise by combustion in the furnace, and temperature rise by self-heating by power generation, and the start-up is completed.

The illustrated oxidizing gas supply line 42 is a flow path that supplies air compressed by the compressor 15 of the MGT 10 and heat-exchanged by the air heater 12 to the air electrode of the SOFC 20. The oxidizing gas supply line 42 is provided with an in-furnace combustion fuel gas supply line 44 for supplying fuel from the oxidizing gas supply line 42 into the power generation chamber for combustion in the furnace. The fuel gas for in-furnace combustion merges with air at the junction of the in-furnace combustion fuel gas supply line 44 and the oxidizing gas supply line 42 and is supplied to the power generation chamber 50 of the SOFC 20. Burn for purpose.
The oxidizing gas discharge flow path 43 is a flow path for supplying air supplied to the SOFC 20 and used for power generation to the MGT 10.

  The control device 30 includes, for example, a CPU (Central Processing Unit) (not shown), a RAM (Random Access Memory), a computer-readable recording medium, and the like. A series of processing steps for realizing various functions to be described later are recorded in a recording medium or the like in the form of a program, and the CPU reads the program into a RAM or the like to execute information processing / arithmetic processing. Thus, various functions described later are realized.

  In the combined power generation system 1 using the SOFC 20 and the MGT 10, when the SOFC 20 is activated, a first temperature increase control (temperature increase by air supplied from the compressor 15 of the MGT 10) and a second temperature increase control ( (Temperature rise by supplying fuel from the oxidizing gas supply line 42 to the power generation chamber and burning in the furnace in the power generation chamber) is performed. In this embodiment, the following control is performed. Thus, the first temperature rise control is effectively switched to the second temperature rise control so as to minimize heat loss and time loss.

First, the first temperature rise control when the temperature of the power generation chamber of the SOFC 20 is lower than the first predetermined temperature will be described.
When the temperature of the power generation chamber of the SOFC 20 is lower than the first predetermined temperature, the control device 30 performs temperature increase control that prevents stress deformation of the metal member. For example, the control device 30 performs control so that air adjusted to a temperature range of about 300 to 500 ° C. is supplied from the MGT 10 to the SOFC 20 with a small flow rate. Specifically, the control device 30 operates the MGT 10 with a constant load having a low output, thereby supplying air at about 450 to 500 ° C. according to the temperature increase rate, thereby increasing the temperature of the SOFC 20.

  In order to adjust the air supplied to the SOFC 20 to a temperature range of about 300 to 500 ° C., not only the output of the MGT 10 is adjusted, but also the air flow rate that flows through the second bypass path 18 to bypass the air heater 12 is adjusted. It may be adjusted by increasing the number (that is, controlling the opening degree of the bypass valve 13 in the opening direction).

Here, the temperature distribution in the power generation chamber means that when there is a power generation chamber 50 as shown in FIG. 2, the power generation chamber 50 is divided into a plurality of regions in the vertical direction (in this embodiment, three regions). The distribution states of temperatures detected at the upper part T1, the central part T2, and the lower part T3 in the case of the upper part T1, the central part T2, and the lower part T3 in order from the top are shown.
When the air is supplied from the lower part in the power generation chamber 50 as shown in FIG. 2, the control unit 30 causes the temperature of the region of the lower part T3 to be lower than the temperature of the upper part T1 and the central part T2. It is preferable to reduce the temperature distribution by controlling at least one of the supply amount and the temperature of the air supplied to the SOFC 20.

  The control device 30 prevents the temperature difference between the metal members constituting the power generation chamber 50 from becoming larger than the allowable temperature difference of the temperature distribution in the power generation chamber 50, that is, “the temperature difference of the metal member ≦ the temperature distribution of the power generation chamber. The valve opening degree of the control valve 13 is controlled so as to be within the management range indicated by “temperature difference”, and the amount of air that bypasses the air heater 12 via the second bypass path 18 is increased. Thereby, since the flow rate of the air passing through the air heater 12 is reduced, the temperature of the air supplied from the oxidizing gas supply line 42 to the SOFC 20 is lowered. For example, when the MGT 10 is operated at a constant load and air of 400 to 500 ° C. is supplied to the SOFC 20, when the control device 30 detects that the temperature difference of the temperature distribution of the power generation chamber 50 exceeds the management range, the control device 30 The opening degree of the control valve 13 is controlled so that the air temperature in the oxidizing gas supply line 42 is lower than the air temperature before detection, and the temperature of the power generation chamber 50 is maintained without increasing the temperature of the power generation chamber 50. To control.

Further, the control device 30 controls the temperature distribution in the power generation chamber 50 to be reduced by reducing the temperature of the air supplied from the oxidizing gas supply line 42.
That is, when it is detected that the temperature distribution becomes larger and exceeds the management range, the control for lowering the temperature of the supply air is executed as control for stopping the temperature increase control of the SOFC 20 and reducing the temperature distribution.
When the temperature distribution of the power generation chamber 50 becomes less than the allowable temperature difference, the valve opening degree of the control valve 13 is controlled, the air flow rate through the air heater 12 is increased, and the air supply at a higher temperature is resumed. The temperature is controlled to continue.

  The control device 30 supplies a predetermined temperature increase rate of the power generation chamber 50 until the temperature of the power generation chamber 50 reaches the first predetermined temperature after supplying compressed air having a relatively low temperature from the MGT 10 to the SOFC 20 at a small flow rate for a predetermined period. The flow rate of the compressed air supplied from the MGT 10 is increased and the flow rate is adjusted so as to comply with the above.

  The control device 30 supplies the air to the SOFC 20 while maintaining the air flow rate and the air temperature set in this way, and when the temperature of the power generation chamber 50 is detected to be equal to or higher than the first predetermined temperature, the control device 30 starts from the first temperature increase control. 2 Switch to temperature rise control.

Next, the second temperature rise control when the temperature of the power generation chamber of the SOFC 20 is higher than the first predetermined temperature will be described.
When the temperature of the power generation chamber 50 becomes higher than the first predetermined temperature, temperature increase control by in-furnace combustion is started. In this case, if the temperature in the lower T3 region is high, combustion of the in-furnace combustion fuel gas proceeds in the lower T3. Therefore, in-furnace combustion fuel gas supply is performed so that combustion does not proceed in the lower T3 region. The amount of combustion in the region of the lower T3 can be reduced by adjusting the amount so as to match the temperature increase rate and using the control for reducing the air supply amount and the control for lowering the air temperature in combination. Therefore, combustion in the region of the lower portion T3 that is in the vicinity of the portion that supplies air to the power generation chamber 50 increases, and it is possible to prevent the temperature of the power generation chamber 50 from excessively rising.

That is, the temperature of the power generation chamber 50 is increased according to the temperature increase rate, and when the temperature deviates from the temperature increase rate to the higher temperature side (overheating side), the valve opening degree of the control valve 11 is controlled in the opening direction. It is preferable to adjust the air temperature by reducing the flow rate of air supplied to the SOFC 20 and reducing the output of the MGT 10 to optimize the combustion state and the temperature distribution of the power generation chamber 50.
Note that the supply amount of the in-furnace combustion fuel gas supplied to the SOFC 20 is preferably controlled so as to match the temperature increase rate. Moreover, when the temperature distribution of the power generation chamber 50 becomes larger than a predetermined value, it is preferable to reduce the supply amount of the combustion fuel in the furnace or to stop it.

  When the temperature of the power generation chamber 50 of the SOFC 20 becomes equal to or higher than the first predetermined temperature and the temperature distribution in the power generation chamber 50 exceeds the allowable value, the control device 30 determines the supply amount of the in-furnace combustion fuel gas supplied to the SOFC 20 Alternatively, the supply of the in-furnace combustion fuel gas to the SOFC 20 may be stopped to suppress the spread of the temperature distribution.

  Furthermore, in the second temperature rise control, when the temperature of the power generation chamber 50 immediately before the start of power generation reaches a second predetermined temperature of about 800 ° C., the temperature difference between the central portion T2 and the lower portion T3 of the power generation chamber 50 is It is preferable that the temperature is controlled to be within a management range of 50 ° C. to 100 ° C. (that is, the temperature of the lower portion T3 is lower by 50 ° C. to 100 ° C. than the central portion T2).

  When the temperature difference between the metal members constituting the power generation chamber 50 becomes larger than the allowable temperature difference of the temperature distribution in the power generation chamber 50, the control device 30 adjusts the combustion amount of the furnace combustion to be low. Therefore, when the valve opening degree of the control valve 45 is controlled and the temperature difference between the metal members constituting the power generation chamber 50 becomes equal to or less than the allowable temperature difference of the temperature distribution in the power generation chamber 50, the valve opening of the control valve 45 is stopped. Resume control.

  Since the controller 30 completes the combined operation of the SOFC 20 and the MGT 10 and supplies the SOFC 20 with compressed air having a relatively low temperature relative to the power generation chamber temperature, the control device 30 sets the allowable temperature difference in the temperature distribution of the power generation chamber 50. While maintaining within the management range, the flow rate and temperature of the compressed air supplied from the MGT 10 can also be adjusted so that the temperature increase of the power generation chamber 50 follows a predetermined temperature increase rate.

  The control device 30 can also adjust the temperature distribution of the power generation chamber 50 by using the control based on the supply amount of the in-furnace combustion fuel gas and the control based on the flow rate and temperature of the compressed air alone or in combination.

  Hereinafter, the operation of the control device 30 of the combined power generation system 1 according to the present embodiment will be described with reference to FIGS. 1 to 4. 3 (a) and 3 (b) show the elapsed time on the horizontal axis, respectively, but the same time numbers (t0 to t6) in FIGS. 3 (a) and 3 (b) indicate the same time. Yes. Also, the x line in FIG. 3A indicates the air flow rate supplied from the MGT 10 to the SOFC 20, the y line indicates the output of the MGT 10, and the z line is input to the SOFC 20 for combustion in the furnace of the SOFC 20. The flow rate of fuel is shown. Further, T1, T2, and T3 described in the graph of FIG. 3B indicate power generation chamber temperatures (° C.) in the respective regions of the upper T1, the center T2, and the lower T3 of the power generation chamber 50, respectively.

  In the combined operation (combined operation) between the SOFC 20 and the MGT 10 of the combined power generation system 1, city gas as fuel is input to the SOFC 20, and the chemical energy of the fuel is directly converted into electric power by the SOFC 20. Thereafter, the exhaust fuel gas from the SOFC 20 is supplied to the combustor 14 of the MGT 10. On the other hand, the air introduced into the compressor 15 is pressurized and then supplied to the SOFC 20, and after being partially used as an oxidant (oxidizing gas), it is sent again to the MGT 10 together with the high-temperature exhaust heat, so that the air has Heat and pressure are also converted into electric power on the downstream MGT 10 side as energy, so that high power generation efficiency can be obtained in the entire system.

  At time t0 in FIG. 3, the valve opening degree of the control valve 11 is controlled in the opening direction, the MGT 10 is started to operate at a low output, and the valve opening degree of the bypass valve 13 is controlled in the opening direction (step SA1 in FIG. 4). . Then, in the initial stage, pressurization is performed with pressurized air, and then the temperature of the power generation chamber 50 of the SOFC 20 starts to rise gently. At this time, the air temperature supplied from the MGT 10 to the SOFC 20 is lower than when the output of the MGT 10 is large. Further, since the opening degree of the bypass valve 13 is controlled in the opening direction, the flow rate of the compressed air flowing through the second bypass path 18 without passing through the air heater 12 of the MGT 10 increases, and the temperature of the air discharged from the air heater 12 Is controlled to be relatively low. Further, when the valve opening degree of the control valve 11 is controlled in the opening direction, the air flow rate flowing through the first bypass path 17 is increased, and the air flow rate supplied to the SOFC 20 is relatively reduced.

  At time t1 in FIG. 3 after the lapse of a predetermined period, the valve opening degree of the control valve 11 is controlled in the closing direction according to the temperature of the power generation chamber 50, and the oxidizing gas that supplies the exhaust gas that passes through the SOFC 20 to the MGT 10 Controlling the supply of exhaust air from the gas exhaust passage 43 to the combustor 14, reducing the air flow rate flowing through the first bypass path 17, and increasing the air flow rate supplied from the MGT 10 to the SOFC 20 shifts to the combined operation. (Step SA2 in FIG. 4). When the flow rate of air supplied from the MGT 10 to the SOFC 20 is increased, the temperature of the power generation chamber 50 is increased as the air flow rate is increased as shown in FIG. At time t2 in FIG. 3, the supply air flow rate to the SOFC 20 is made constant, and then the bypass valve 13 is closed (step SA3 in FIG. 4). Then, since the compressed air discharged via the air heater 12 increases, the air temperature rises.

  Thereafter, at time t3, the output of the MGT 10 is increased according to the temperature of the power generation chamber 50 (step SA4 in FIG. 4). Then, the temperature of the air supplied from the MGT 10 to the SOFC 20 increases, and the temperature of the power generation chamber 50 further increases. At time t4, the output of the MGT 10 becomes constant, and then the first temperature rise control is continued, and the temperature of the power generation chamber 50 continues to rise.

It is determined whether or not the temperature of the power generation chamber 50 has reached a first predetermined temperature (for example, 450 ° C.) (step SA5 in FIG. 4), and it is detected that the first predetermined temperature has been reached at time t5. If this happens, switching from the first temperature rise control to the second temperature rise control is started.
When it is detected that the temperature of the power generation chamber 50 has reached the first predetermined temperature, the fuel for combustion in the furnace of the SOFC 20 is increased and combustion in the furnace is started (step SA6 in FIG. 4). At the same time, the valve opening of the bypass valve 13 is adjusted in the opening direction, and is adjusted so as to reduce the output of the MGT 10 (step SA7 in FIG. 4). Furthermore, the valve opening degree of the control valve 11 is adjusted in the opening direction, and the flow rate of air supplied from the MGT 10 to the SOFC 20 is decreased (step SA8 in FIG. 4).

Since the SOFC 20 has started in-furnace combustion, the temperature of the power generation chamber 50 continues to rise, but air having a temperature lower than the supply air from the MGT 10 that was supplied when the first temperature increase control was being performed. Since the air is supplied, the temperature rise in the lower portion T3, which is the portion for supplying air in the power generation chamber 50 (near the air inlet), becomes slower than the upper portion T1 and the central portion T2. By continuously reducing the output of the MGT 10 and reducing the flow rate of air supplied from the MGT 10 to the SOFC 20, the temperature difference between the lower T3 of the power generation chamber 50 to which air is supplied, and the upper T1 and the center T2 gradually increases. Become bigger.
When it is detected at time t6 that the temperature of the air supplied from the MGT 10 (the temperature of the air near the outlet of the MGT 10) is a desired value (for example, 420 ° C. or lower), Therefore, it is determined that the temperature can prevent an abnormal increase in the in-furnace combustion, and the supplied air flow rate, the output of the MGT 10 and the fuel flow rate for the in-furnace combustion of the SOFC 20 are held.

  At the second predetermined temperature immediately before the start of power generation, the temperature difference between the central portion T2 and the lower portion T3 is 50 ° C to 100 ° C (that is, the temperature of the lower portion T3 is 50 ° C to 100 ° C lower than the central portion T2). It is preferable that the temperature difference is controlled. When such a temperature difference is detected, the second temperature increase control is terminated and the power generation control is started.

  As described above, according to the control device 30 of the combined power generation system 1 and the combined power generation system 1 including the same and the control method 1 of the combined power generation system 1 according to the present embodiment, the SOFC 20 and the SOFC 20 are discharged. A combustor 14 for burning fuel, a gas turbine 16 driven by combustion gas supplied from the combustor 14, a compressor 15 for compressing air, and an air heater 12 for heating the air compressed by the compressor 15; In the control device 30 of the combined power generation system 1 that generates electric power by performing cooperative operation in combination with the MGT 10 including the air, the air compressed by the compressor 15 is heated by the air heater 12 and is discharged from the outlet of the air heater 12 to the SOFC 20. The first air to be supplied to the combustor 14 from the air to be supplied and the path for supplying the SOFC 20 Because it is divided into air flowing through the paths path 17, the control valve 11 provided on the first bypass passage 17 is adjusted in the opening direction, the air flow supplied to the SOFC20 is less than before the adjustment. When the output of the MGT 10 is controlled to decrease, the temperature of the air supplied to the SOFC 20 is made lower than when the output of the MGT 10 is not decreased. As a result, when the temperature of the power generation chamber 50 of the SOFC 20 becomes equal to or higher than a first predetermined temperature (for example, 450 ° C.), fuel is supplied to the SOFC 20 and burned in the furnace. The flow rate of the air supplied to the battery can be reduced, and the temperature can be adjusted low.

  In the combined power generation system 1 using the SOFC 20 and the MGT 10, when the SOFC 20 is started, in order to increase the temperature of the power generation chamber 50, two-step temperature increase control of first temperature increase control and second temperature increase control is performed. According to the invention, in the second temperature increase control, the flow rate of the air supplied to the SOFC 20 is adjusted according to the temperature of the power generation chamber 50 of the SOFC 20, so that there is much supply air at a temperature lower than the temperature of the power generation chamber 50. This prevents the combustion field in the furnace combustion from being hindered from hindering the temperature rise.

  Further, since the temperature of the air supplied to the SOFC 20 is adjusted according to the temperature of the power generation chamber 50 of the SOFC 20, a portion (air) that supplies air to the power generation chamber 50 when the temperature of the supply air is high in the second temperature rise control. In this embodiment, it is possible to prevent the combustion at the lower portion T3) from increasing and the temperature from locally rising so that the combustion at the upper portion T1 and the central portion T2 is prevented. Moreover, since it can suppress that the electric power generation room 50 heated up by 1st temperature rising control is lowered | hung by this, switching from the 1st temperature rising control at the time of power generation room temperature rising to 2nd temperature rising control is efficient. Thus, heat loss and time loss can be minimized, and the time required to start up the SOFC 20 can be shortened accordingly.

  In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary, it can change suitably.

1 Combined power generation system (fuel cell / gas turbine power generation system)
10 MGT (micro gas turbine)
11 Control valve 12 Air heater (A / H)
13 Bypass valve 14 Combustor 20 SOFC (Solid oxide fuel cell)
30 Control device 50 Power generation room

Claims (10)

A control device for a combined power generation system that generates power by combining a fuel cell and an internal combustion engine,
The internal combustion engine is compressed by the combustor that burns the fuel discharged from the fuel cell, a gas turbine that is driven by combustion gas supplied from the combustor, a compressor that compresses air, and the compressor. Heat exchange means for heating the air;
A first bypass path for bypassing the air to the combustor from a path for circulating the air heated in the heat exchange means to the fuel cell;
A control valve for adjusting the flow rate of the air flowing through the first bypass path,
When the temperature of the power generation chamber of the fuel cell is equal to or higher than a first predetermined temperature that can be combusted in the furnace, while supplying fuel to the fuel cell and combusting in the furnace, according to the temperature of the power generation chamber, A control device for a combined power generation system that adjusts a valve opening of the control valve and adjusts an output of the internal combustion engine.   2. The control device for a combined power generation system according to claim 1, wherein an amount of the fuel supplied to the fuel cell is adjusted to follow a predetermined temperature increase rate of the power generation chamber.   When the temperature of the power generation chamber of the fuel cell is equal to or higher than a first predetermined temperature and the temperature distribution in the power generation chamber exceeds an allowable value, the amount of fuel supplied to the fuel cell is reduced, or the fuel The control apparatus of the combined power generation system according to claim 1 or 2, wherein the supply of power is stopped. A second bypass path for bypassing the air compressed by the compressor to the outlet of the heat exchange means without passing through the heat exchange means;
The control device for a combined power generation system according to any one of claims 1 to 3, further comprising a bypass valve that adjusts a flow rate of the air flowing through the second bypass path.   When the temperature of the power generation chamber of the fuel cell is lower than the first predetermined temperature, the temperature difference of the metal member constituting the power generation chamber is less than the allowable temperature difference of the temperature distribution in the power generation chamber. The control apparatus of the combined power generation system according to any one of claims 1 to 4, which controls a flow rate and a temperature of the air supplied from an internal combustion engine to the fuel cell.   When the temperature difference of the metal member constituting the power generation chamber becomes larger than the allowable temperature difference of the temperature distribution in the power generation chamber, the control of the valve opening of the control valve and the output of the internal combustion engine When at least one of the controls is temporarily stopped, and the temperature difference of the metal member constituting the power generation chamber becomes equal to or less than the allowable temperature difference of the temperature distribution in the power generation chamber, the valve of the control valve The combined power generation system control device according to claim 5, wherein the control of the opening degree and the control of the output of the internal combustion engine are resumed. The flow rate of the air supplied to the fuel cell is increased so as to follow a predetermined rate of temperature increase of the power generation chamber until the temperature of the power generation chamber reaches the first predetermined temperature. A control device for a combined power generation system according to claim 1. The power generation chamber is divided into a plurality of regions in the vertical direction, and is divided into an upper part, a central part, and a lower part in order from the top, and when the air is supplied from the lower part,
Among the supply amount of the fuel supplied to the fuel cell, the supply amount of air, and the temperature of the air so that the temperature of the lower region is lower than the temperature of the upper portion and the central portion, The control apparatus of the combined power generation system according to any one of claims 1 to 7, wherein at least one of them is adjusted.   A combined power generation system comprising a fuel cell, the control device according to any one of claims 1 to 8, and the internal combustion engine. A fuel cell, a combustor that burns fuel discharged from the fuel cell, a gas turbine that is driven by combustion gas supplied from the combustor, a compressor that compresses air, and the air that is compressed by the compressor A control method for a combined power generation system that generates power in combination with an internal combustion engine having heat exchange means for heating
When the temperature of the power generation chamber of the fuel cell is equal to or higher than a first predetermined temperature that can be combusted in the furnace, while supplying fuel to the fuel cell and combusting in the furnace, according to the temperature of the power generation chamber, Adjusting a control valve for adjusting a flow rate of the air to be circulated from a path through which the air heated in the heat exchange means is circulated to the fuel cell to a first bypass path for bypassing the air to the combustor; and A control method of a combined power generation system for adjusting the output of the internal combustion engine.

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