JP7478987B2 - Method for operating fuel processor, computer program, recording medium, and fuel processor - Google Patents

Description

The present disclosure relates to a method for operating a fuel processor, a computer program, a recording medium, and a fuel processor.

The fuel processor of Patent Document 1 includes a reformer, a CO reducer, a combustor, a flame detector, and a controller. The reformer produces hydrogen-containing gas from a feedstock mainly composed of hydrocarbons. The CO reducer reduces the carbon monoxide concentration of the hydrogen-containing gas. The combustor heats at least one selected from the group consisting of the reformer and the CO reducer. The flame detector detects the presence or absence of a flame in the combustor. Patent Document 1 describes an operating method in which a flame detector detects a hydrocarbon flame when the hydrogen generation device is started. In Patent Document 1, a flame rod is used as the flame detector.

JP 2018-090461 A

This disclosure provides technology that uses a flame rod as a flame detector and makes it possible to detect a flame even when the raw material contains hydrogen and carbon monoxide and almost no hydrocarbons.

The present disclosure relates to
A reformer;
A CO remover;
a combustor for heating the reformer;
a fluid machine that forms a fluid flow in which a fluid flows through the reformer, the CO remover, and the combustor in this order;
a flame rod through which an ion current flows according to a combustion state of the combustor;
A method for operating a fuel processor comprising:
A raw material containing hydrogen and carbon monoxide and having a hydrocarbon concentration below the lower flammable limit is supplied to the reformer;
An operation of the heater heating the CO remover is defined as a heating operation;
When the operation of the fluid machine to form the fluid flow by supplying the raw material to the reformer is defined as a flow forming operation,
The operating method includes:
Initiating the heating operation; and
and commencing the flow forming operation after commencing the heating operation, thereby supplying the fluid having a higher hydrocarbon concentration than the feedstock to the combustor.
Provide a method of operation.

The present disclosure relates to
A reformer;
A CO remover;
a combustor for heating the reformer;
a fluid machine that forms a fluid flow in which a fluid flows through the reformer, the CO remover, and the combustor in this order;
a flame rod through which an ion current flows according to a combustion state of the combustor;
A method for operating a fuel processor comprising:
An operation of the heater heating the CO remover is defined as a heating operation;
When the operation of the fluid machine to supply the raw material to the reformer to form the fluid flow is defined as a flow forming operation,
The operating method includes:
Initiating the heating operation; and
and after starting the heating operation, starting to perform the flow forming operation while performing the heating operation.
Provide a method of operation.

The present disclosure relates to
A reformer;
A CO remover;
a combustor for heating the reformer;
a fluid machine that forms a fluid flow in which a fluid flows through the reformer, the CO remover, and the combustor in this order;
a flame rod through which an ion current flows according to a combustion state of the combustor;
a heater for heating the CO remover;
A fuel processor including a controller that executes a heating control for causing the heater to heat the CO remover, and a flow formation control for causing the fluid machine to form the fluid flow by supplying a raw material to the reformer,
In a predetermined operation of the fuel processor, after the heating control is started, the flow formation control is started while the heating control is being performed.
A fuel processor is provided.

The technology disclosed herein makes it possible to detect a flame using a flame rod as a flame detector, even when the raw material contains hydrogen and carbon monoxide and almost no hydrocarbons.

Block diagram of a fuel processor according to a first embodiment. FIG. 1 is a characteristic diagram showing the relationship between the raw material supply time, the detected temperature of the reformer temperature detector, and the methane concentration in the first gas in the first embodiment. FIG. 1 is a characteristic diagram showing the relationship between the raw material supply time and the methane concentration in the second gas in the first embodiment. FIG. 1 is a characteristic diagram showing the relationship between the methane concentration in the fuel and the current value of the flame rod in the first embodiment. 1 is a flowchart showing a system operation of a fuel processor according to the first embodiment. Block diagram of a fuel processor according to a second embodiment. 1 is a flowchart showing a system operation of a fuel processor according to a second embodiment.

(Knowledge and other information that forms the basis of this disclosure)
At the time when the inventors came up with the present disclosure, fuel processors had been under study. In one example of a conventional fuel processor, at start-up, hydrocarbons are supplied to a reformer as a raw material. The hydrocarbons are passed through the reformer and the CO reducer and then supplied to a combustor as a fuel. The combustor heats the reformer by burning the fuel. A flame in the combustor is detected by a flame detector.

A flame rod is sometimes used as a flame detector. The flame rod is a metal rod. The flame rod is combined with a power source and a current sensor to form a current detection circuit. When the flame rod is exposed to a flame, an ion current flows through the flame rod. This current is detected by the current sensor. The state of the flame is determined based on the magnitude of the detected value.

When there are few hydrocarbons in the flame, not enough ion current may flow through the flame rod. In this case, a false determination may be made that a flame is not formed, when in fact a flame is formed.

There are techniques to avoid erroneous judgments like the one above. For example, when using anode off-gas as fuel for the combustor, the temperature of the reformer is adjusted so that the hydrocarbons contained in the anode off-gas reach a predetermined concentration or higher.

However, some raw materials contain almost no hydrocarbons such as methane. When using such raw materials, it is not easy to generate a sufficient ion current during combustion, and flame detection is not easy. Even in a situation where a flame is expected to be formed, if a flame cannot be detected, the supply of fuel to the combustor must be stopped for safety reasons. This can make it impossible to start the fuel processor.

Therefore, this disclosure provides a technology that uses a flame rod as a flame detector and makes it possible to detect a flame even when the raw material contains hydrogen and carbon monoxide and almost no hydrocarbons.

Below, the embodiments will be described in detail with reference to the drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to make it easier for those skilled in the art to understand.

The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure and are not intended to limit the subject matter described in the claims.

(Embodiment 1)
Hereinafter, the first embodiment will be described with reference to FIG. 1 to FIG.

[1-1. Configuration]
1 , the fuel processor 41 includes a reformer 2, a CO remover 4, a combustor 5, a raw material supplier 6, a heater 9, a reformer temperature detector 12, a CO remover temperature detector 14, an igniter 15, a flame rod 16, and a controller 11. Hereinafter, the reformer temperature detector 12 may be referred to as a first detector 12. The CO remover temperature detector 14 may be referred to as a second detector 14.

A reforming catalyst (not shown) is installed inside the reformer 2. In this embodiment, the reforming catalyst is a catalyst in which ruthenium is supported on an alumina carrier.

A raw material is supplied to the reformer 2. In the reformer 2, a methanation reaction using the raw material occurs. In this methanation reaction, methane and water vapor are produced from hydrogen and carbon monoxide contained in the raw material, as shown in the following chemical formula 1. Hereinafter, the gas present at the outlet of the reformer 2 is referred to as a first gas. Hereinafter, the outlet of the reformer 2 is an outlet that opens toward the CO remover 4, in detail.
Chemical formula 1: _3H2 + CO → _CH4 + _H2O

In this embodiment, the raw material contains hydrogen and carbon monoxide. Meanwhile, the concentration of hydrocarbons in the raw material is below the lower flammable limit. The raw material may contain almost no hydrocarbons. The raw material containing almost no hydrocarbons means, for example, that the concentration of hydrocarbons in the raw material is less than 2% by volume.

In one example, the feedstock is endothermic reformed gas. In one numerical example, the hydrogen concentration in the feedstock is 41 vol. %. The carbon monoxide concentration in the feedstock is 20 vol. %. The nitrogen concentration in the feedstock is 39 vol. %. The hydrocarbon concentration in the feedstock is less than 0.1 vol. %. In the experiments described below with reference to Figures 2 to 4, the endothermic reformed gas according to this numerical example was used.

The CO remover 4 is equipped with a CO removal catalyst (not shown). In this embodiment, the CO removal catalyst is a selective oxidation catalyst. In this embodiment, the CO removal catalyst is a catalyst in which ruthenium is supported on an alumina carrier.

Gas is supplied to the CO remover 4 from the reformer 2. This gas contains hydrogen and carbon monoxide. In the CO remover 4, a methanation reaction occurs using this gas. In this methanation reaction, methane and water vapor are produced from the hydrogen and carbon monoxide contained in the gas, as shown in the following chemical formula 2. Hereinafter, the gas present at the outlet of the CO remover 4 is referred to as a second gas. Hereinafter, the outlet of the CO remover 4 is an outlet that opens toward the combustor 5, in detail.
Chemical formula 2: _3H2 +CO→ _CH4 + _H2O

The combustor 5 mixes fuel and air and burns them. This heats the reformer 2. The gas supplied from the CO remover 4 is used as fuel for the combustor 5.

The raw material supplier 6 supplies raw material to the reformer 2. In this embodiment, the raw material supplier 6 is a pump.

The heater 9 heats the CO remover 4. In this embodiment, the heater 9 is an electric heater. The electric heater may be a resistance heater or an infrared heater. In one numerical example, the power consumption of the electric heater is 500 W.

The first detector 12 detects the temperature of the reforming catalyst installed in the reformer 2. In this embodiment, the first detector 12 is a thermocouple.

The second detector 14 detects the temperature of the CO removal catalyst installed in the CO remover 4. In this embodiment, the second detector 14 is a thermocouple.

The igniter 15 ignites the mixture of fuel and air supplied to the combustor 5. In this embodiment, the igniter 15 ignites by spark discharge.

The flame rod 16 is a metal rod. The flame rod 16 is combined with a power source and a current sensor (not shown) to form a current detection circuit. When the flame rod 16 is exposed to a flame, an ion current flows through the flame rod 16. This current is detected by the current sensor. The state of the flame is determined based on the magnitude of the detected value.

The controller 11 controls the raw material supplier 6, the heater 9, and the igniter 15. Specifically, the controller 11 controls the raw material supplier 6, the heater 9, and the igniter 15 using the first detector 12 and the second detector 14.

The expression "The raw material supplier 6 performs XXX" can be read as "The controller 11 controls the raw material supplier 6 so that the raw material supplier 6 performs XXX." The expression "The heater 9 performs XXX" can be read as "The controller 11 controls the heater 9 so that the heater 9 performs XXX." The expression "The igniter 15 performs XXX" can be read as "The controller 11 controls the igniter 15 so that the igniter 15 performs XXX."

[1-2. motion]
The operation and function of the fuel processor 41 configured as above will be described below. The operation method of the fuel processor 41 includes four steps, in this order: a standby step, a start-up step, a power generation step, and a stop step. .

During the standby process, the temperatures of the reformer 2, the CO remover 4, and the combustor 5 are maintained near room temperature. During the standby process, the raw material supplier 6, the heater 9, the igniter 15, and the current detection circuit do not operate. The standby process continues until the start-up process begins.

In the startup process, first, the heater 9 heats the CO remover 4 so that the temperature of the CO remover 4 rises to a predetermined range. This predetermined range is the temperature range in which the methanation reaction produces methane in the CO remover 4 at a concentration required for flame detection with the flame rod 16. In this embodiment, this predetermined range is from 150°C to 250°C.

In the startup process, the raw material supplier 6 and igniter 15 are then operated. This causes combustion in the combustor 5. The combustor 5 heats the reformer 2 through combustion so that the temperature of the reformer 2 rises to a predetermined range. This predetermined range is the temperature range in which methane is produced from the raw material through a methanation reaction at a concentration required for flame detection with the flame rod 16. In this embodiment, this predetermined range is from 150°C to 550°C.

When the temperature of the reformer 2 is in the range of 150°C to 550°C, the start-up process is completed. Then, the process moves to the power generation process.

In the power generation process, the gas generated by the CO remover 4 is continuously and stably supplied to a hydrogen-utilizing device (not shown). The fuel processor 41 continues the power generation process until it transitions to the shutdown process.

In the stop process, the reformer 2 and the CO remover 4 are cooled so that the temperatures of the reformer 2 and the CO remover 4 drop to near room temperature. When the temperatures of the reformer 2 and the CO remover 4 drop to near room temperature, the process transitions to the standby process.

Hereinafter, the terms first threshold temperature T _th1 , interval ΔT, second threshold temperature T _th2 , and third threshold temperature T _th3 may be used. The first threshold temperature T _th1 is the temperature T ₁₄ detected by the second detector 14 when starting to supply raw material to the reformer 2, and is the temperature at which it is expected that continuous detection of a flame by the flame rod 16 becomes possible. The interval ΔT is the increase in the first threshold temperature T _th1 for each control cycle when, contrary to this expectation, it is impossible to detect a flame by the flame rod 16. The second threshold temperature T _th2 is the upper limit temperature in terms of durability of the CO removal catalyst. The third threshold temperature T _th3 is the temperature T ₁₂ detected by the first detector 12, and is the temperature at which methane is expected to be produced from the raw material in the reformer 2.

The first threshold temperature T _th1 will be specifically described with reference to FIG. 2 to FIG.

The production of methane in the CO remover 4 can contribute to realizing a state in which a flame can be detected by the flame rod 16. Hereinafter, this contribution will be referred to as a first contribution. Moreover, the production of methane in the reformer 2 can contribute to realizing a state in which a flame can be detected by the flame rod 16. Hereinafter, this contribution will be referred to as a second contribution. The first threshold temperature T _th1 is a value of the detection temperature T ₁₄ of the second detector 14 for enabling continuous detection of a flame by the flame rod 16 by at least one of the first contribution and the second contribution.

Fig. 2 is a characteristic diagram showing the relationship among the raw material supply time, the detected temperature _T12 of the first detector 12, and the methane concentration in the first gas in the first embodiment. In Fig. 2, the solid line represents the detected temperature _T12 . The dashed and dotted line represents the methane concentration in the first gas. In the following description of Fig. 2, the unit of methane concentration, % is volume % with respect to the total volume of the first gas.

The plot shown in FIG. 2 was obtained by the following experiment. That is, the endothermic converted gas according to the above numerical example was used as the raw material. With the igniter 15 operating and the heater 9 not operating, the raw material was supplied from the raw material supply device 6 to the reformer 2 at 1 mol/min. This formed a flow of fluid flowing from the reformer 2 to the combustor 5 via the CO remover 4, and the fluid was supplied to the combustor 5 as fuel, and the reformer 2 was heated by combustion of the fuel. The relationship of the detected temperature T ₁₂ to the raw material supply time to the reformer 2 was plotted. Also, the methane concentration in the first gas was plotted against the raw material supply time. The methane concentration in the first gas was measured by a non-dispersive infrared absorption analyzer.

As shown in Fig. 2, 12 minutes after the start of the raw material supply, the detected temperature _T12 of the first detector 12 exceeded 250°C, and the methane concentration in the first gas began to increase. 14 minutes after the start of the raw material supply, the temperature of the reformer temperature detector exceeded 350°C, and the methane concentration in the first gas exceeded 1%. When the detected temperature _T12 reached 420°C, the methane concentration in the first gas reached 5%. Thereafter, as the detected temperature _T12 increased, the methane concentration in the first gas decreased.

2, in the region where the detection temperature _T12 is relatively low, the methane concentration increases as the detection temperature _T12 increases. This is believed to be because the reaction rate of the methanation reaction in the reforming catalyst increases as the temperature of the reforming catalyst increases. On the other hand, in the region where the detection temperature _T12 is relatively high, the methane concentration decreases as the detection temperature _T12 increases. This is believed to be because the equilibrium point of the methanation reaction in the reforming catalyst shifts toward hydrogen and carbon monoxide as the temperature of the reforming catalyst increases.

Figure 3 is a characteristic diagram showing the relationship between the raw material supply time and the methane concentration in the second gas in embodiment 1. In the following description of Figure 3, the unit of methane concentration, %, is the volume % with respect to the total volume of the second gas.

The plots shown in FIG. 3 were obtained by the following first, second and third experiments. That is, the same endothermic reformed gas as the endothermic reformed gas used in the experiment for obtaining the plots in FIG. 2 was used as the raw material. With the igniter 15 not in operation, the raw material was supplied from the raw material supply device 6 to the reformer 2 at 1 mol/min. Specifically, the supply of the raw material to the reformer 2 was started when the detection temperature T 14 of the CO remover detector 14 reached a predetermined temperature by heating the CO remover ₄ with the heater 9. Specifically, in the first experiment, the predetermined temperature was 150° C. In the second experiment, the predetermined temperature was 200° C. In the third experiment, the predetermined temperature was 250° C. In the first, second and third experiments, the methane concentration in the second gas was plotted against the raw material supply time. The methane concentration in the second gas was measured by a non-dispersive infrared absorption analyzer.

In all three of the first, second and third experiments, the methane concentration in the second gas began to increase immediately after the start of the raw material supply. The methane concentration reached its maximum value when 1 to 1.5 minutes had elapsed since the start of the raw material supply. Thereafter, the methane concentration decreased.

In the first experiment, the period during which the methane concentration in the second gas was 1% or higher was 12 minutes from immediately after the start of raw material supply. In the second experiment, the period during which the methane concentration in the second gas was 1% or higher was 15 minutes from immediately after the start of raw material supply. In the first experiment, the period during which the methane concentration in the second gas was 1% or higher was 19 minutes from immediately after the start of raw material supply.

Figure 4 is a characteristic diagram showing the relationship between the methane concentration in the fuel and the current value of the flame rod 16 in embodiment 1. The current value of the flame rod 16 is specifically the value of the ion current flowing through the flame rod 16. In the following explanation of Figure 4, the unit of methane concentration, % is the volume % with respect to the total volume of the fuel.

The plot shown in Figure 4 was obtained by the following experiment. That is, the same endothermic reformed gas as that used in the experiments to obtain the plots in Figures 2 and 3 was used as the raw material. However, in the experiment to obtain the plots in Figure 4, a mixed fluid was generated by adding methane to this raw material. The mixed fluid was supplied from the raw material supply 6 to the reformer 2 at 1 mol/min without heating the CO remover detector 14 by the heater 9, and the mixed fluid was supplied to the combustor 5 as fuel. During this supply, the methane concentration of the mixed fluid was changed by gradually increasing the amount of methane added to the raw material, while the current value of the flame rod 16 was measured. As a result, the current value of the flame rod 16 was plotted against the methane concentration in the fuel. The methane concentration in the fuel was measured by a non-dispersive infrared absorption analyzer.

As shown in FIG. 4, the higher the methane concentration in the fuel, the larger the ion current value. The current detection circuit using the flame rod 16 can detect a flame in a region where the ion current is 0.4×10 ⁻⁶ A or more. An ion current of 0.4×10 ⁻⁶ A corresponds to a methane concentration of 0.4%. However, in order to reliably determine the presence or absence of a flame, it is better to pass an ion current greater than 0.4×10 ⁻⁶ A. Therefore, when determining the first threshold temperature T _th1 as described below, the threshold concentration is set to 1% instead of 0.4%. Then, when the detection value of the ion current is equal to or greater than the threshold current corresponding to this threshold concentration, it is determined that a flame exists, and when the detection value of the ion current is less than this threshold current, it is determined that a flame does not exist.

Based on the above explanation, the basis for determining the first threshold temperature T _th1 will be summarized.

The startup process of this embodiment includes a period in which the heater 9 heats the CO remover 4 without supplying new raw material to the reformer 2 before starting the combustion of fuel in the combustor 5. The fact that new raw material is not being supplied to the reformer 2 means that no gas flow is formed in the CO remover 4. Therefore, during the above period, although the reaction rate of the methanation reaction in the CO remover 4 is slow, it is easier to ensure the contact time between the gas and the CO removal catalyst in the CO remover 4 compared to when raw material is being supplied. Therefore, high-concentration methane can be generated in the CO remover 4. In this context, the contact time between the gas and the CO removal catalyst refers to the time during which the mass of gas located around the CO removal catalyst remains around the CO removal catalyst without being replaced by fresh gas.

On the other hand, when the supply of raw material to the reformer 2 starts, the methane stored inside the CO remover 4 is pushed toward the combustor 5. This causes the methane concentration in the second gas to rise to a concentration higher than 1%. However, the methane concentration in the second gas subsequently falls to 1% or less. This is because a gas flow is formed in the CO remover 4 when the supply of raw material to the reformer 2 starts, and the contact time between the gas and the CO removal catalyst in the CO remover 4 is shortened.

Therefore, methane is supplied from the reformer 2 so that the methane concentration in the second gas is maintained at a level higher than 1% after the supply of raw material to the reformer 2 begins. Specifically, before the concentration of methane in the second gas originating from the CO remover 4 falls to 1% or less, the methanation reaction in the reformer 2 is promoted to increase the methane concentration in the first gas to a level higher than 1%. In this way, the reformer 2 contributes to maintaining the methane concentration in the second gas at a level higher than 1%. By maintaining the methane concentration in the second gas at a level higher than 1%, continuous detection of a flame by the flame rod 16 becomes possible.

According to the above study with reference to Fig. 2, in order to make the methane concentration in the first gas higher than 1%, it is necessary to supply raw material to the reformer 2 for at least 14 minutes. During this period, it is necessary to realize a state in which the methane concentration in the second gas is higher than 1% by the CO remover 4. According to the above study with reference to Fig. 3, if raw material supply to the reformer 2 is started at the time when the detection temperature _T14 of the CO remover detector 14 reaches 200°C, the methane concentration in the second gas can be maintained at 1% or more for 15 minutes (>14 minutes) from immediately after the start of raw material supply. Therefore, in this embodiment, the first threshold temperature _Tth1 is set to 200°C.

Next, we will explain the step size ΔT.

When the carbon monoxide concentration of the raw endothermic converted gas is low, it is possible to increase the temperature of the CO remover 4 in order to obtain a methane concentration at which a flame can be detected using the flame rod 16 through a methanation reaction. In typical real-world control, when the temperature of the CO remover 4 needs to be increased, the temperature of the CO remover 4 is increased by a predetermined increase amount for each control cycle. The step width ΔT corresponds to this increase amount.

The situation where the carbon monoxide concentration in the endothermic converted gas is low can occur in the following way: the endothermic converted gas can be produced from hydrocarbons. The carbon monoxide concentration in the endothermic converted gas depends on the composition of the hydrocarbons.

In the methanation reaction, methane is produced from carbon monoxide and hydrogen. If the carbon monoxide concentration of the endothermic converted gas is low, the reaction rate of the methanation reaction is slow. Therefore, the reaction rate of the methanation reaction is increased by increasing the reaction temperature of the methanation reaction. This creates a situation in which the concentration of methane is likely to increase in the CO remover 4. Specifically, as can be seen from FIG. 3, by increasing the temperature of the CO remover 4 to increase the reaction rate of the methanation reaction, the methane concentration in the second gas can be maintained at the desired level for a sufficient period of time.

Specifically, in the start-up process of this embodiment, when the detection temperature _T14 of the second detector 14 reaches the first threshold temperature _Tth1 , the supply of raw material to the reformer 2 by the raw material supplier 6 and the ignition operation of the combustor 5 by the igniter 15 are started. If a flame cannot be detected using the flame rod 16 despite the start of these operations, it is determined that the methane concentration in the fuel has not reached a concentration required for flame detection, and the first threshold temperature _Tth1 is updated to a temperature obtained by adding the step width ΔT to the first threshold temperature _Tth1 . This can promote the production of methane.

In this embodiment, the step size ΔT is 10°C. If the step size ΔT is this high, the control responsiveness can be sufficiently ensured. If the step size ΔT is this low, the control stability can be sufficiently ensured. Also, if the step size ΔT is this low, it is unlikely that a situation will occur in which the amount of methane supplied to the combustor 5 increases rapidly, causing the combustion in the combustor 5 to become unstable.

Next, the second threshold temperature T _th2 will be described.

As described above, the second threshold temperature T _th2 is the upper limit temperature in terms of durability of the CO removal catalyst. The CO removal catalyst of this embodiment is obtained by dispersing ruthenium on an alumina carrier. When exposed to an environment with a higher temperature than the temperature at which it is normally used, ruthenium aggregates and its surface area decreases. When the surface area decreases, the area that contributes to the functioning of the CO removal catalyst decreases, and the CO removal capacity may decrease in a short period of time. Therefore, the second threshold temperature T _th2 can be set so that the necessary capacity as a CO removal catalyst can be exerted at least for a time exceeding the design life of the fuel processor 41. In this embodiment, the second threshold temperature T _th2 is 250° C.

The third threshold temperature T _th3 is the detection temperature T ₁₂ of the first detector 12, and is the temperature at which methane is expected to be produced from the raw material in the reformer 2. Specifically, the third threshold temperature T _th3 is the temperature at which methane is expected to be produced from the hydrogen and carbon monoxide filled in the reformer 2. According to the above consideration with reference to FIG. 2, when the detection temperature T ₁₂ is 350° C. or higher, the methane concentration in the first gas becomes higher than 1%. The third threshold temperature T _th3 can be set based on this. In this embodiment, the third threshold temperature T _th3 is 350° C.

Next, the system operation of the fuel processor 41 will be explained in more detail using Figure 5.

When the startup process begins, the fuel processor 41 performs the following operations:

In step S101, the heater 9 starts a heating operation. The heating operation is an operation for heating the CO remover 4. Specifically, in step S101, the controller 11 controls the heater 9 so that the heater 9 starts a heating operation.

The heating operation started in step S101 can promote the production of methane from the hydrogen and carbon monoxide filled in the CO remover 4. The start-up process can be started with hydrogen and carbon monoxide filled in the fuel processor 41. This is for the following reason, for example. If appropriate measures are not taken, the water vapor added in the reaction to reduce the carbon monoxide concentration derived from the raw material can condense on the catalyst as its temperature drops, deteriorating the catalyst. To avoid this situation, the water vapor is removed by supplying raw material into the fuel processor 41 in the stop process of the fuel processor 41. This hydrogen and carbon monoxide derived from the raw material remains in the fuel processor 41 even when the start-up process is started thereafter.

After step S101, in step S102, the controller 11 determines whether or not the condition that the detected temperature _T14 of the second detector 14 is equal to or higher than the first threshold temperature _Tth1 is satisfied. If this condition is satisfied, the process proceeds to step S103. If this condition is not satisfied, the process proceeds to step S102. That is, step S102 is repeatedly executed until the detected temperature _T14 reaches the first threshold temperature _Tth1 . When the detected temperature _T14 reaches the first threshold temperature _Tth1 , the process proceeds to step S103.

In step S103, the igniter 15 starts the ignition operation. Specifically, in step S103, the controller 11 controls the igniter 15 so that the igniter 15 starts the ignition operation. The ignition operation is an operation of igniting the combustor 5. In this embodiment, the ignition operation is an operation of generating a spark.

After step S103, in step S104, the raw material supply device 6 starts a raw material supply operation. Specifically, in step S104, the controller 11 controls the raw material supply device 6 so that the raw material supply device 6 starts a raw material supply operation. The raw material supply operation is an operation of supplying raw material to the reformer 2.

Steps S103 and S104 start the combustion of fuel in the combustor 5. Note that steps S103 and S104 may be performed simultaneously.

After step S104, in step S105, the controller 11 determines whether or not the condition that a flame has been detected by the flame rod 16 is satisfied. If this condition is satisfied, the process proceeds to step S106. If this condition is not satisfied, the process proceeds to step S151.

The above condition in step S105 can also be explained using the term ion current. That is, the above condition is that the ion current flowing through the frame rod 16 is equal to or greater than a threshold current. Specifically, the above condition is that the detection value of the ion current by the current detection circuit is equal to or greater than a threshold current.

In step S151, the raw material supply device 6 stops the raw material supply operation. Specifically, in step S151, the controller 11 controls the raw material supply device 6 so that the raw material supply device 6 stops the raw material supply operation.

After step S151, in step S152, the igniter 15 stops the ignition operation. Specifically, in step S152, the controller 11 controls the igniter 15 so that the igniter 15 stops the ignition operation.

Steps S151 and S152 stop the combustion of fuel in the combustor 5. In this embodiment, the igniter 15 stops the ignition operation after the raw material supply device 6 stops the raw material supply operation. In this way, even if a flammable fluid leaks from at least one selected from the group consisting of the reformer 2 and the CO remover 4 after the raw material supply operation of the raw material supply device 6 is stopped, the flammable fluid can be completely combusted.

After step S152, in step S153, the controller 11 updates the first threshold temperature T _th1 to a temperature obtained by adding the step size ΔT to the first threshold temperature T _th1 .

By updating step S153, even if the carbon monoxide concentration in the raw material is low, it becomes easier for methane of a concentration sufficient for flame detection by the flame rod 16 to be produced in the CO remover 4.

After step S153, in step S154, the controller 11 determines whether or not the condition that the detected temperature _T14 of the second detector 14 is equal to or higher than the second threshold temperature _Tth2 is satisfied. If this condition is satisfied, the process proceeds to step S155. If this condition is not satisfied, the process proceeds to step S102.

In step S155, the heater 9 stops the heating operation. Specifically, in step S155, the controller 11 controls the heater 9 so that the heater 9 stops the heating operation.

In steps S154 and S155, when the detected temperature T ₁₄ is equal to or greater than the second threshold temperature T _th2 , the heating of the CO remover 4 by the heater 9 is stopped. This can prevent the CO removal ability of the CO removal catalyst from decreasing in a short period of time.

After step S155, the startup process ends. Then, the process moves to the standby process.

In step S106, the igniter 15 stops the ignition operation. Specifically, in step S106, the controller 11 controls the igniter 15 so that the igniter 15 stops the ignition operation.

After step S106, in step S107, the controller 11 determines whether or not the condition that the detected temperature _T12 of the first detector 12 is equal to or higher than the third threshold temperature _Tth3 is satisfied. If this condition is satisfied, the process proceeds to step S108. If this condition is not satisfied, the process proceeds to step S107. That is, step S107 is repeatedly executed until the detected temperature _T12 reaches the third threshold temperature _Tth3 . When the detected temperature _T12 reaches the third threshold temperature _Tth3 , the process proceeds to step S108.

In step S108, the heater 9 stops the heating operation. Specifically, in step S108, the controller 11 controls the heater 9 so that the heater 9 stops the heating operation.

In steps S107 and S108, when the detection temperature T ₁₂ ≧the third threshold temperature T _th3 , the heating of the CO remover 4 by the heater 9 is stopped. This makes it possible to stop the generation of methane in the CO remover 4 after the temperature of the reformer 2 has risen to a temperature at which methane of a concentration sufficient for detecting a flame by the flame rod 16 can be generated in the reformer 2.

After step S108, the startup process ends. Then, the process moves to the power generation process.

When methane and steam come into contact with the reforming catalyst, not only the steam reforming reaction but also the methanation reaction proceeds. The steam reforming reaction is a reaction in which hydrogen and carbon monoxide are produced from methane and steam. The methanation reaction is a reaction in the opposite direction to the steam reforming reaction. In other words, the methanation reaction is a reaction in which methane and steam are produced from hydrogen and carbon monoxide. These reactions reach equilibrium at a concentration that depends on the temperature. Taking a hint from this, the inventors came up with the idea of using a reforming catalyst to produce methane from the raw materials hydrogen and carbon monoxide. After further investigation, the inventors came up with the technology related to this embodiment.

[1-3. Effects, etc.]
As described above, in this embodiment, the fuel processor 41 includes the reformer 2, the CO remover 4, the combustor 5, the igniter 15, the fluid machine, the frame rod 16, the heater 9, and the controller 11. The reformer 2 has a reforming catalyst. The CO remover 4 has a CO removal catalyst. The combustor 5 heats the reformer 2. The igniter 15 ignites the combustor 5. The fluid machine forms a fluid flow in which a fluid flows through the reformer 2, the CO remover 4, and the combustor 5 in this order. An ion current according to the combustion state of the combustor 5 flows through the flame rod 16. The heater 9 heats the CO remover 4. In the example of FIG. 1, the fluid machine is the raw material supplier 6.

Hereinafter, the operation of the heater 9 to heat the CO remover 4 is referred to as the heating operation. The operation of the fluid machine to form the above-mentioned fluid flow by supplying raw material to the reformer 2 is referred to as the flow forming operation. The operation of the igniter 15 to ignite the combustor 5 is referred to as the ignition operation. The ignition operation is, for example, an operation to generate a spark.

Hereinafter, the control that causes the heater 9 to heat the CO remover 4 is referred to as heating control. The control that causes the fluid machine to form the above-mentioned fluid flow by supplying the raw material to the flow reformer 2 is referred to as flow formation control. The control that causes the igniter 15 to ignite the combustor 5 is referred to as ignition control. Ignition control is, for example, control that causes spark generation. The controller 11 performs heating control, flow formation control, and ignition control.

In this embodiment, a raw material containing hydrogen and carbon monoxide and having a hydrocarbon concentration below the lower flammable limit is supplied to the reformer 2. The operating method of the fuel processor 41 includes a step of starting a heating operation. The operating method includes a step of starting a flow forming operation after starting the heating operation, thereby supplying a fluid having a higher hydrocarbon concentration than the raw material to the combustor 5. According to this configuration, the fuel processor 41 generates hydrocarbons having a higher concentration than the hydrocarbon concentration in the raw material, and the ion current can be increased to above the detection limit by supplying the high-concentration hydrocarbons to the combustor 5. Therefore, this configuration makes it possible to detect a flame even when a flame rod 16 is used as a flame detector and the raw material contains hydrogen and carbon monoxide and almost no hydrocarbons.

Specifically, according to the above configuration, the fuel processor 41 can be started with hydrogen and carbon monoxide filled in the fuel processor 41. This is, for example, due to the following reason. That is, if appropriate measures are not taken, the water vapor added in the reaction to reduce the carbon monoxide concentration derived from the raw material may condense on the catalyst as its temperature drops, causing the catalyst to deteriorate. To avoid such a situation, the water vapor is removed by supplying raw material into the fuel processor 41 in the shutdown process of the fuel processor 41. This hydrogen and carbon monoxide derived from the raw material remain in the fuel processor 41 even when the fuel processor 41 is started up again. Since the fuel processor 41 can be started with hydrogen and carbon monoxide filled in the fuel processor 41, hydrocarbons can be produced from hydrogen and carbon monoxide by heating the fuel processor 41. Therefore, flame detection by the flame rod 16 is possible even when raw material containing almost no hydrocarbons is used.

The lower flammable limit of a hydrocarbon is the minimum concentration of the hydrocarbon required for combustion of the hydrocarbon to occur. Examples of hydrocarbons are methane, ethane, propane, butane, etc. The lower flammable limit of methane is 5.0 vol.%. The lower flammable limit of ethane is 3.0 vol.%. The lower flammable limit of propane is 2.1 vol.%. The lower flammable limit of butane is 1.8 vol.%. In the above context, "the concentration of the hydrocarbon is less than the lower flammable limit" may be read as "the concentration of the hydrocarbon is less than 5.0 vol.%."

In this embodiment, the above-mentioned process of starting the flow forming operation is a process of starting the flow forming operation while performing the heating operation. Performing the flow forming operation while performing the heating operation is advantageous from the viewpoint of ensuring the amount of hydrocarbons produced in the CO remover 4 and increasing the concentration of hydrocarbons supplied to the combustor 5.

In this embodiment, the period during which the flow forming operation is performed includes a first period, a second period, and a third period. The second period is a period following the first period. The third period is a period following the second period. The first period is a period during which the concentration of hydrocarbons in the fluid in the combustor 5 increases due to the hydrocarbons generated in the CO remover 4. The second period is a period during which the concentration of hydrocarbons in the fluid in the combustor 5 decreases. The third period is a period during which the concentration of hydrocarbons in the fluid in the combustor 5 increases due to the hydrocarbons generated in the reformer 2. In this configuration, the concentration of hydrocarbons supplied to the combustor 5 can be maintained at a sufficient level due to the hydrocarbons generated in the CO remover 4 and the hydrocarbons generated in the reformer 2. Therefore, an ion current equal to or greater than the detection limit can be continuously generated.

The above expression "hydrocarbon concentration of the fluid in the combustor 5" will now be explained. In this expression, "fluid in the combustor 5" specifically refers to the fluid at the flame nozzle of the combustor 5.

Typically, the increase in the concentration of hydrocarbons in the CO remover 4 is due to the production of methane in the CO remover 4. The increase in the concentration of hydrocarbons in the reformer 2 is due to the production of methane in the reformer 2.

In this embodiment, the carbon monoxide concentration in the feedstock is 5% by volume or more. The hydrogen concentration in the feedstock is 30% by volume or more. The hydrocarbon concentration in the feedstock is 2% by volume or less. A feedstock having this composition can be used in the fuel processor 41 of this embodiment. Specifically, the carbon monoxide concentration in the feedstock can be 6% by volume or more and 25% by volume or less. The hydrogen concentration in the feedstock can be 30% by volume or more and 48% by volume or less. The hydrocarbon concentration in the feedstock can be 1% by volume or less.

In one example, the raw material is exhaust gas generated outside the fuel processor 41. The exhaust gas can be used as a raw material to be supplied to the fuel processor 41 of this embodiment. In one specific example, the exhaust gas can be generated outside the fuel processor by at least one selected from the group consisting of combustion and chemical reaction. The exhaust gas is, for example, exhaust gas from an industrial device.

In this embodiment, the operating method is executed when the fuel processor 41 is started.

In this embodiment, the operating method includes a step of starting a heating operation. The operating method includes a step of starting a flow forming operation while performing the heating operation after starting the heating operation. This configuration makes it possible to detect a flame even when a flame rod 16 is used as a flame detector and the raw material contains hydrogen and carbon monoxide and almost no hydrocarbons.

Specifically, in this embodiment, the operating method includes a process of starting the ignition operation and the flow forming operation while performing the heating operation after starting the heating operation. With this configuration, unnecessary ignition operations can be avoided, and it is easy to avoid a shortened life of the igniter 15. Note that the expression "performing the ignition operation and the flow forming operation" is intended to mean that the start time of the ignition operation and the start time of the flow forming operation may be the same or different, and that the stop time of the ignition operation and the stop time of the flow forming operation may be the same or different. The same applies to the expressions "starting the ignition operation and the flow forming operation" and "stopping the ignition operation and the flow forming operation".

In this embodiment, the operating method includes a step of stopping the flow forming operation when the ion current is relatively small after starting the flow forming operation. The operating method includes a step of continuing the flow forming operation when the ion current is relatively large after starting the flow forming operation. When the ion current is relatively small, it cannot be excluded that the fuel is not being burned in the combustor 5 even though the fuel is being supplied to the combustor 5. In such a case, the supply of the raw material to the reformer 2 can be stopped. Also, when the ion current is relatively large, it is understood that the fuel supplied to the combustor 5 is being burned in the combustor 5. In such a case, the supply of the raw material to the reformer 2 can be continued. "When the ion current is relatively large" specifically means "when the ion current is equal to or larger than the threshold current". "When the ion current is relatively small" specifically means "when the ion current is smaller than the threshold current".

Specifically, the operating method includes a step of stopping the ignition operation and the flow forming operation when the ion current is relatively small after starting the ignition operation and the flow forming operation. The operating method includes a step of continuing the flow forming operation when the ion current is relatively large after starting the ignition operation and the flow forming operation.

In this embodiment, the operating method includes a step of starting a flow forming operation while performing a heating operation when the temperature of the CO removal catalyst is equal to or higher than a first threshold temperature. The operating method includes a step of updating the first threshold temperature to a higher value after stopping the flow forming operation due to a relatively small ion current. The operating method includes a step of resuming the flow forming operation while performing a heating operation when the temperature of the CO removal catalyst is equal to or higher than the first threshold temperature after updating the first threshold temperature. With this configuration, it is possible to increase the amount of hydrocarbons generated in the CO remover 4 when the ion current is relatively small. This is useful, for example, when endothermic shift gas is used as the raw material and the carbon monoxide concentration of the endothermic shift gas is low. The first threshold temperature is given, for example, as the temperature of the CO removal catalyst when methane can be generated by the CO removal catalyst.

Specifically, the operating method includes a step of starting an ignition operation and a flow forming operation while performing a heating operation when the temperature of the CO removal catalyst is equal to or higher than a first threshold temperature. The operating method includes a step of updating the first threshold temperature to a higher value after stopping the ignition operation and the flow forming operation due to a relatively small ion current. The operating method includes a step of resuming the ignition operation and the flow forming operation while performing a heating operation after updating the first threshold temperature when the temperature of the CO removal catalyst is equal to or higher than the first threshold temperature.

In this embodiment, the operating method includes a step of stopping the ignition operation after the flow forming operation is stopped due to the relatively small ion current. With this configuration, even if a flammable fluid leaks from at least one selected from the group consisting of the reformer 2 and the CO remover 4 after the raw material supply operation of the raw material supply device 6 is stopped, the flammable fluid can be completely combusted.

In this embodiment, the operating method includes a step of stopping the heating operation when the temperature of the CO removal catalyst is equal to or higher than the second threshold temperature after the flow forming operation is stopped due to the relatively small ion current. This configuration can prevent the CO removal ability of the CO removal catalyst from decreasing in a short period of time. The second threshold temperature is given, for example, as the upper limit temperature of the durability of the CO removal catalyst. Typically, the second threshold temperature is higher than the first threshold temperature.

Specifically, the operating method includes a step of stopping the heating operation when the temperature of the CO removal catalyst is equal to or higher than a second threshold temperature after stopping the ignition operation and the flow forming operation due to the relatively small ion current.

In this embodiment, the operating method includes a step of stopping the heating operation when the flow forming operation continues due to a relatively large ion current and the temperature of the reforming catalyst is equal to or higher than the third threshold temperature. With this configuration, the production of hydrocarbons in the CO remover 4 can be stopped after the temperature of the reformer 2 has risen to a temperature at which methane of a concentration sufficient for flame detection by the flame rod 16 can be produced in the reformer 2. The third threshold temperature is given, for example, as the temperature of the reforming catalyst when methane can be produced by the reforming catalyst.

In this embodiment, the operating method is executed when the fuel processor 41 is started.

A computer program can be realized that, when executed by a computer, has instructions for causing a computer to execute the above-mentioned operating method. A computer-readable non-transient recording medium can be realized on which the above-mentioned computer program is recorded. The recording medium may be an offline recording medium or an online recording medium. Offline recording media include, for example, semiconductor recording media such as HDD, SD card, and USB memory, magnetic recording media such as flexible disks, magneto-optical recording media such as MO, and optical recording media such as CDs and DVDs. Online recording media include, for example, cloud servers, FTP servers, and network storage.

In this embodiment, during a given operation of the fuel processor 41, after heating control is started, flow formation control is started while performing heating control.

Specifically, during a given operation, after heating control has started, ignition control and flow formation control are started while performing heating control.

In this embodiment, during a specified operation, after flow formation control is started, when the ion current is relatively small, the flow formation control is stopped. During a specified operation, after flow formation control is started, when the ion current is relatively large, the flow formation control is continued.

Specifically, in a specified operation, after ignition control and flow formation control are started, when the ion current is relatively small, ignition control and flow formation control are stopped. In a specified operation, after ignition control and flow formation control are started, when the ion current is relatively large, flow formation control is continued.

In this embodiment, in a predetermined operation, after heating control is started, when the temperature of the CO removal catalyst is equal to or higher than the first threshold temperature, flow formation control is started while performing heating control. In a predetermined operation, after flow formation control is stopped due to a relatively small ion current, the first threshold temperature is updated to a higher value. In a predetermined operation, after the first threshold temperature is updated, flow formation control is resumed while performing heating control when the temperature of the CO removal catalyst is equal to or higher than the first threshold temperature.

Specifically, in a predetermined operation, after heating control is started, when the temperature of the CO removal catalyst is equal to or higher than the first threshold temperature, ignition control and flow formation control are started while performing heating control. In a predetermined operation, after ignition control and flow formation control are stopped due to a relatively small ion current, the first threshold temperature is updated to a higher value. In a predetermined operation, after the first threshold temperature is updated, ignition control and flow formation control while performing heating control are resumed while performing heating control when the temperature of the CO removal catalyst is equal to or higher than the first threshold temperature.

In this embodiment, during a given operation, the ion current is relatively small, so flow formation control is stopped, and then ignition control is stopped.

In this embodiment, during a given operation, after flow formation control is stopped due to a relatively small ion current, heating control is stopped when the temperature of the CO removal catalyst is equal to or higher than the second threshold temperature.

Specifically, during a given operation, after ignition control and flow formation control are stopped due to a relatively small ion current, heating control is stopped when the temperature of the CO removal catalyst is equal to or higher than the second threshold temperature.

In this embodiment, during a given operation, when the ion current is relatively large, flow formation control continues, and the temperature of the reforming catalyst is equal to or higher than the third threshold temperature, heating control is stopped.

In this embodiment, the specified operation is performed when the fuel processor 41 is started.

Other embodiments are described below. Elements common to the previous and following embodiments are given the same reference symbols, and their description may be omitted. The descriptions of each embodiment may be mutually applicable, so long as there is no technical contradiction. Each embodiment may be combined with each other, so long as there is no technical contradiction.

(Embodiment 2)
The second embodiment will be described below with reference to FIGS.

[2-1. Configuration]
In Fig. 6, the fuel processor 42 includes a CO reducer 3, a water supplier 7, an oxidizing gas supplier 8, and a CO reducer temperature detector 13. The fuel processor 42 also includes a heater 10 instead of the heater 9. In Fig. 6, a hydrogen utilization device 51 is shown. The hydrogen utilization device 51 is disposed outside the fuel processor 42. Hereinafter, the CO reducer temperature detector 13 may be referred to as a third detector 13.

The CO reducer 3 is equipped with a conversion catalyst (not shown). In this embodiment, the conversion catalyst is an alloy of copper and zinc.

The CO reducer 3 reduces the concentration of carbon monoxide contained in the gas supplied from the reformer 2. In the CO reducer 3 of this embodiment, an aqueous shift reaction occurs. In this aqueous shift reaction, carbon dioxide and hydrogen are produced from carbon monoxide and water vapor, as shown in the following chemical formula 3.
Chemical formula 3: CO + _H2O → _CO2 + _H2

The water supplier 7 supplies water to the reformer 2. In this embodiment, the water supplier 7 is a pump.

The oxidizing gas supplier 8 supplies oxidizing gas to the CO remover 4. In this embodiment, the oxidizing gas supplier 8 is a pump. The oxidizing gas is air.

The heater 10 heats the CO reducer 3 and the CO remover 4, and also heats the reformer 2. Specifically, the heater 10 is disposed adjacent to the CO reducer 3 and the CO remover 4. The heater 10 directly heats the CO reducer 3 and the CO remover 4. The reformer 2 is thermally coupled to the CO reducer 3. The heater 10 indirectly heats the reformer 2 by thermal conduction from the CO reducer 3. In this embodiment, the heater 10 is an electric heater. The electric heater may be a resistance heating type heater or an infrared heater. It is a heater. In one numerical example, the power consumption of the electric heater is 500 W.

The third detector 13 detects the temperature of the conversion catalyst installed in the CO reducer 3. In this embodiment, the third detector 13 is a thermocouple.

The controller 11 controls the raw material supplier 6, the water supplier 7, the oxidizing gas supplier 8, the heater 10, and the igniter 15. Specifically, the controller 11 controls the raw material supplier 6, the water supplier 7, the oxidizing gas supplier 8, the heater 10, and the igniter 15 using the first detector 12, the third detector 13, and the second detector 14.

The expression "water supplier 7 performs XXX" can be read as "controller 11 controls water supplier 7 so that water supplier 7 performs XXX." The expression "oxidizing gas supplier 8 performs XXX" can be read as "controller 11 controls oxidizing gas supplier 8 so that oxidizing gas supplier 8 performs XXX." The expression "heater 10 performs XXX" can be read as "controller 11 controls heater 10 so that heater 10 performs XXX."

The gas generated in the CO remover 4 is supplied to the hydrogen utilization device 51. The gas not consumed in the hydrogen utilization device 51 is supplied to the combustor 5 of the fuel processor 42.

In this embodiment, the hydrogen utilization device 51 is, for example, a fuel cell. In one specific example, the hydrogen utilization device 51 is a polymer electrolyte fuel cell. In this specific example, the polymer electrolyte fuel cell generates electricity by an electrochemical reaction between hydrogen supplied to the anode and oxygen supplied to the cathode. The catalyst used in the anode of the polymer electrolyte fuel cell is vulnerable to carbon monoxide. The concentration of carbon monoxide allowed to maintain the performance of the anode is 10 ppm or less.

[2-2. motion]
The operation and function of the fuel processor 42 configured as above will be described below.

First, the fourth threshold temperature T _th4 and the fifth threshold temperature T _th5 will be described.

The fourth threshold temperature T _th4 is the detection temperature T ₁₂ of the first detector 12, and is the temperature at which water vapor is expected not to condense inside the reformer 2. Metal particles used in the reforming catalyst may oxidize when they come into contact with liquid water, and their ability as a reforming catalyst may decrease. This problem can be avoided by evaporating the water supplied to the reformer 2 before it reaches the reforming catalyst. The fourth threshold temperature T _th4 can be set based on this. In this embodiment, the fourth threshold temperature T _th4 is 150° C.

The fifth threshold temperature T _th5 is the detected temperature T ₁₃ of the third detector 13, and is the temperature at which a shift reaction is expected to occur in the CO reducer 3. Specifically, the fifth threshold temperature T _th5 is the temperature at which carbon dioxide and hydrogen are expected to be produced from carbon monoxide and water vapor contained in the gas supplied to the CO reducer 3 by the shift reaction. The shift reaction has the following characteristics.
The higher the temperature during the shift reaction, the faster the reaction rate of the shift reaction. Assuming that the contact time between the gas and the shift catalyst is infinitely long, the higher the temperature during the shift reaction, the higher the concentration of carbon monoxide after the reaction. The lower the temperature during the shift reaction, the slower the reaction rate of the shift reaction. Assuming that the contact time between the gas and the shift catalyst is infinitely long, the lower the temperature during the shift reaction, the lower the concentration of carbon monoxide after the reaction. In this context, the contact time between the gas and the shift catalyst refers to the time during which the mass of gas located around the shift catalyst continues to be in contact with the shift catalyst without being replaced with fresh gas. In the CO reducer 3, a flow of gas originating from the raw material supplier 6 is formed, so the contact time between the gas and the shift catalyst is finite. Therefore, when the temperature of the shift catalyst of the CO reducer 3 is neither too low nor too high, the concentration of carbon monoxide in the gas flowing out from the CO reducer 3 to the CO remover 4 is the lowest. According to an experiment conducted by the inventors, the detection temperature T ₁₃ of the third detector 13 at which this concentration is the lowest is 250°C. Taking this into consideration, the fifth threshold temperature T _th5 can be set. In this embodiment, the fifth threshold temperature T _th5 is 250°C.

Next, the system operation of the fuel processor 42 will be explained in more detail using Figure 7.

When the start-up process begins, the fuel processor 42 performs the following operations. Note that, in the following, explanations of steps similar to those in the first embodiment shown in FIG. 5 will be omitted.

In step S201, the heater 10 starts a heating operation. The heating operation is an operation of heating the CO remover 4. The heating operation is also an operation of heating the CO reducer 3. The heating operation is also an operation of heating the reformer 2. Specifically, in step S201, the controller 11 controls the heater 10 so that the heater 10 starts a heating operation.

The heating operation started in step S201 can promote the production of methane from the hydrogen and carbon monoxide filled in the CO remover 4. The heating operation can promote the production of carbon dioxide and hydrogen from the carbon monoxide and water vapor contained in the gas supplied to the CO reducer 3. The heating operation can evaporate the water supplied to the reformer 2.

After step S201, in step S202, the controller 11 determines whether or not all of the following three conditions are met. If all three conditions are met, the process proceeds to step S103. If at least one of the three conditions is not met, the process proceeds to step S202. In other words, step S202 is repeatedly executed until all three conditions are met. If all three conditions are met, the process proceeds to step S103.

The three conditions in step S201 include a first condition, a second condition, and a third condition. The first condition is that the detected temperature _T12 of the first detector 12 is equal to or higher than a fourth threshold temperature _Tth4 . The second condition is that the detected temperature _T13 of the third detector 13 is equal to or higher than a fifth threshold temperature _Tth5 . The third condition is that the detected temperature _T14 of the second detector 14 is equal to or higher than a first threshold temperature _Tth1 .

After step S103, in step S204, the water supplier 7 starts a water supply operation. Specifically, in step S204, the controller 11 controls the water supplier 7 so that the water supplier 7 starts a water supply operation. The water supply operation is an operation of supplying water to the reformer 2. After step S204 is completed, the process proceeds to step S104.

The water supply operation started in step S204 enables the carbon monoxide concentration to be reduced, for example to 1% or less, through a shift reaction in the CO reducer 3.

After step S104, in step S206, the oxidizing gas supply device 8 starts the oxidizing gas supply operation. Specifically, in step S206, the controller 11 controls the oxidizing gas supply device 8 so that the oxidizing gas supply device 8 starts the oxidizing gas supply operation. The oxidizing gas supply operation is an operation of supplying oxidizing gas to the CO remover 4. After step S204 is completed, the process proceeds to step S105.

The oxidizing gas supply operation started in step S206 enables carbon monoxide to be removed by the carbon monoxide oxidation reaction in the CO remover 4.

In embodiment 2, if the condition in step S105 is not met, the process proceeds to step S251.

In step S251, the oxidizing gas supply device 8 stops the oxidizing gas supply operation. Specifically, in step S251, the controller 11 controls the oxidizing gas supply device 8 so that the oxidizing gas supply device 8 stops the oxidizing gas supply operation. After step S251 is completed, the process proceeds to step S151.

By stopping the oxidizing gas supply operation in step S251, the carbon monoxide oxidation reaction in the CO remover 4 can be stopped.

After step S151, in step S253, the water supply device 7 stops the water supply operation. Specifically, in step S253, the controller 11 controls the water supply device 7 so that the water supply device 7 stops the water supply operation. After step S253 is completed, the process proceeds to step S152.

By stopping the water supply operation in step S253, the shift reaction in the CO reducer 3 can be stopped.

In the second embodiment, the igniter 15 stops the ignition operation after the water supply device 7 stops the water supply operation. In this way, even if a flammable fluid leaks from at least one selected from the group consisting of the reformer 2, the CO reducer 3, and the CO remover 4 after the water supply operation of the water supply device 7 is stopped, the flammable fluid can be completely combusted.

In embodiment 2, if the condition in step S154 is met, the process proceeds to step S257.

In step S257, the heater 10 stops the heating operation. Specifically, in step S257, the controller 11 controls the heater 10 so that the heater 10 stops the heating operation.

After step S257, the startup process ends. Then, the process moves to the standby process.

In embodiment 2, if the condition in step S107 is met, the process proceeds to step S210.

In step S210, the heater 10 stops the heating operation. Specifically, in step S210, the controller 11 controls the heater 10 so that the heater 10 stops the heating operation.

In steps S107 and S210, when the detection temperature T ₁₂ ≧the third threshold temperature T _th3 , the heating of the CO remover 4 by the heater 10 is stopped. This makes it possible to stop the generation of methane in the CO remover 4 after the temperature of the reformer 2 has risen to a temperature at which methane of a concentration sufficient for detecting a flame by the flame rod 16 can be generated in the reformer 2.

After step S210, the startup process ends. Then, the power generation process begins.

Here, the action of step S153 in the second embodiment will be explained. As described above, in the CO remover 4, methane is produced using carbon monoxide. Meanwhile, the CO reducer 3 reduces the concentration of carbon monoxide. However, step S153 increases the temperature of the CO remover 4, thereby improving the methane production action of the CO removal catalyst. Furthermore, step S153 shifts the temperature of the CO reducer 3 away from the temperature at which the carbon monoxide concentration reduction action of the shift catalyst is at its maximum. According to step S153 in the second embodiment, these actions work together to make it easier for methane to be produced in the CO remover 4.

The above-described embodiments are intended to illustrate the technology disclosed herein, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

The present disclosure is applicable to devices that utilize hydrogen extracted from endothermic shift gas. Specifically, the present disclosure is applicable to a fuel cell system that obtains electric power using an endothermic shift gas generator, a gas carburizing furnace, a gas reforming device, and a fuel cell. The present disclosure is also applicable to a hydrogen production system that obtains purified hydrogen using an endothermic shift gas generator, a gas carburizing furnace, and a gas reforming device, as well as a pressure swing adsorption device, a temperature swing adsorption device, or an electrochemical hydrogen purifier.

Reference Signs List 2 Reformer 3 CO reducer 4 CO remover 5 Combustor 6 Raw material supplier 7 Water supplier 8 Oxidizing gas supplier 9 Heater 10 Heater 12 Reformer temperature detector 13 CO reducer temperature detector 14 CO remover temperature detector 15 Igniter 16 Flame detector 41 Fuel processor 42 Fuel processor 51 Hydrogen utilization device

Claims (19)

A reformer;
A CO remover;
a combustor for heating the reformer;
a fluid machine that forms a fluid flow in which a fluid flows through the reformer, the CO remover, and the combustor in this order;
a flame rod through which an ion current flows according to a combustion state of the combustor;
A method for operating a fuel processor comprising:
A raw material containing hydrogen and carbon monoxide and having a hydrocarbon concentration below the lower flammable limit is supplied to the reformer;
An operation of the heater heating the CO remover is defined as a heating operation;
When the operation of the fluid machine to form the fluid flow by supplying the raw material to the reformer is defined as a flow forming operation,
The operating method includes:
Initiating the heating operation; and
and commencing the flow forming operation after commencing the heating operation, thereby supplying the fluid to the combustor, the fluid having a higher hydrocarbon concentration than the feedstock;
The period during which the flow forming operation is performed includes at least a period during which hydrocarbons are produced by a chemical reaction from hydrogen and carbon monoxide contained in the raw material in the reformer.
how to drive. The period during which the flow forming operation is performed includes at least a period during which methane is produced by a methanation reaction from hydrogen and carbon monoxide contained in the raw material in the reformer.
The operating method according to claim 1. and after starting the heating operation, starting to perform the flow forming operation while performing the heating operation.
The operating method according to claim 1 or 2 . The period during which the flow forming operation is performed includes a first period, a second period following the first period, and a third period following the second period;
the first period is a period during which a methane concentration in the fluid at an outlet of the CO remover increases from a concentration equal to or lower than a threshold concentration to a concentration higher than the threshold concentration due to methane generated in the CO remover;
the second time period is a time period during which a concentration of methane in the fluid in the combustor is maintained equal to or greater than the threshold concentration ;
the third period is a period during which a methane concentration in the fluid at an outlet of the reformer increases from a concentration equal to or lower than the threshold concentration to a concentration higher than the threshold concentration due to methane generated in the reformer;
The threshold concentration is 0.4% or more and 1.0% or less.
The operating method according to any one of claims 1 to 3 . The concentration of carbon monoxide in the raw material is 5% by volume or more,
The concentration of hydrogen in the raw material is 30% by volume or more,
The concentration of hydrocarbons in the feedstock is 2% by volume or less.
The operating method according to any one of claims 1 to 4 . The feedstock is exhaust gas generated outside the fuel processor.
The operating method according to any one of claims 1 to 5 . A reformer;
a CO remover having a CO removal catalyst;
a combustor for heating the reformer;
a fluid machine that forms a fluid flow in which a fluid flows through the reformer, the CO remover, and the combustor in this order;
a flame rod through which an ion current flows according to a combustion state of the combustor;
A method for operating a fuel processor comprising:
An operation of the heater heating the CO remover is defined as a heating operation;
When the operation of the fluid machine to supply the raw material to the reformer to form the fluid flow is defined as a flow forming operation,
The operating method includes:
Initiating the heating operation; and
starting to perform the flow forming operation while performing the heating operation when a temperature of the CO removal catalyst is equal to or higher than a first threshold temperature after starting the heating operation;
After starting the flow forming operation, when the ion current is smaller than a threshold current, stopping the flow forming operation;
After starting the flow forming operation, when the ion current is equal to or greater than the threshold current, continuing the flow forming operation;
updating the first threshold temperature to a higher value after the flow forming operation is stopped because the ion current is less than the threshold current;
and resuming the flow forming operation while performing the heating operation when the temperature of the CO removal catalyst is equal to or higher than the first threshold temperature after updating the first threshold temperature.
how to drive. The reformer has a reforming catalyst,
8. The method of claim 7, further comprising stopping the heating operation when the ion current is equal to or greater than the threshold current such that the flow forming operation is continued and the temperature of the reforming catalyst is equal to or greater than a third threshold temperature. a reformer having a reforming catalyst;
A CO remover;
a combustor for heating the reformer;
a fluid machine that forms a fluid flow in which a fluid flows through the reformer, the CO remover, and the combustor in this order;
a flame rod through which an ion current flows according to a combustion state of the combustor;
A method for operating a fuel processor comprising:
An operation of the heater heating the CO remover is defined as a heating operation;
When the operation of the fluid machine to supply the raw material to the reformer to form the fluid flow is defined as a flow forming operation,
The operating method includes:
Initiating the heating operation; and
After starting the heating operation, starting to perform the flow forming operation while performing the heating operation;
After starting the flow forming operation, when the ion current is smaller than a threshold current, stopping the flow forming operation;
After starting the flow forming operation, when the ion current is equal to or greater than the threshold current, continuing the flow forming operation;
and stopping the heating operation when the ion current is equal to or greater than the threshold current so that the flow forming operation is continued and the temperature of the reforming catalyst is equal to or greater than a third threshold temperature.
how to drive. The fuel processor further includes an igniter for igniting the combustor.
When the operation of the igniter to ignite the combustor is defined as an ignition operation,
and stopping the ignition operation after stopping the flow forming operation due to the ion current being less than the threshold current .
The operating method according to any one of claims 7 to 9 . The CO remover has a CO removal catalyst,
and stopping the heating operation when a temperature of the CO removal catalyst is equal to or higher than a second threshold temperature after the flow forming operation is stopped because the ion current is smaller than the threshold current .
The operating method according to any one of claims 7 to 10 . 12. The method of claim 7, wherein the threshold current is greater than or equal to 0.4 microamps. 13. The method of claim 7 , wherein the method is performed at start-up of the fuel processor. A computer program comprising instructions which, when executed by a computer, cause the computer to carry out the method of any one of claims 7 to 13 . A computer-readable non-transitory recording medium on which the computer program according to claim 14 is recorded. A reformer;
a CO remover having a CO removal catalyst;
a CO removal catalyst temperature detector for detecting a temperature of the CO removal catalyst;
a combustor for heating the reformer;
a fluid machine that forms a fluid flow in which a fluid flows through the reformer, the CO remover, and the combustor in this order;
a flame rod through which an ion current flows according to a combustion state of the combustor;
a current sensor for detecting the ion current;
a heater for heating the CO remover;
A fuel processor including a controller that executes a heating control for causing the heater to heat the CO remover, and a flow formation control for causing the fluid machine to form the fluid flow by supplying a raw material to the reformer,
during a predetermined operation of the fuel processor, when the temperature of the CO removal catalyst is equal to or higher than a first threshold temperature after the heating control is started, the flow formation control is started while the heating control is being performed ;
After starting the flow formation control, when the ion current is smaller than a threshold current, the flow formation control is stopped;
After starting the flow formation control, when the ion current is equal to or greater than the threshold current, the flow formation control is continued;
After the flow formation control is stopped because the ion current is smaller than the threshold current, the first threshold temperature is updated to a higher value;
When the temperature of the CO removal catalyst is equal to or higher than the first threshold temperature after the first threshold temperature is updated, the flow formation control is resumed while the heating control is being performed.
Fuel processor. The reformer has a reforming catalyst,
A reformer temperature detector is further provided for detecting the temperature of the reforming catalyst.
the flow formation control is continued because the ion current is equal to or greater than the threshold current, and the temperature of the reforming catalyst is equal to or greater than a third threshold temperature, the heating control is stopped.
17. The fuel processor of claim 16. a reformer having a reforming catalyst;
a reformer temperature detector that detects the temperature of the reforming catalyst;
a CO remover having a CO removal catalyst;
a CO removal catalyst temperature detector for detecting a temperature of the CO removal catalyst;
a combustor for heating the reformer;
a fluid machine that forms a fluid flow in which a fluid flows through the reformer, the CO remover, and the combustor in this order;
a flame rod through which an ion current flows according to a combustion state of the combustor;
a current sensor for detecting the ion current;
a heater for heating the CO remover;
a controller that executes a heating control for causing the heater to heat the CO remover, and a flow formation control for causing the fluid machine to form the fluid flow by supplying a raw material to the reformer,
In a predetermined operation of the fuel processor, after the heating control is started, the flow formation control is started while the heating control is being performed;
After starting the flow formation control, when the ion current is smaller than a threshold current, the flow formation control is stopped;
After starting the flow formation control, when the ion current is equal to or greater than the threshold current, the flow formation control is continued;
the flow formation control is continued because the ion current is equal to or greater than the threshold current, and the temperature of the reforming catalyst is equal to or greater than a third threshold temperature, the heating control is stopped.
Fuel processor. 19. The fuel processor of any one of claims 16 to 18, wherein the threshold current is greater than or equal to 0.4 microamps.

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