JP7002389B2 - Fuel cell power generation system - Google Patents

Description

The present invention relates to a fuel cell power generation system in which raw fuel gas is supplied to a reforming unit at a predetermined flow rate by a fuel supply means, and power generation operation is performed in a cell stack using the fuel gas generated in the reforming unit.

Solid oxide fuel cells (SOFCs) used in fuel cell power generation systems are equipped with electrodes on both sides of a solid electrolyte that conducts oxygen ions, which have the function of oxidizing and reducing oxygen in the fuel gas and oxidant gas, respectively. As a material for the electrolyte, zirconia doped with itria is generally used. Then, the solid oxide fuel cell generates electricity by electrochemically reacting hydrogen, carbon monoxide, hydrocarbon and oxygen in the fuel gas at a high temperature of about 700 ° C to 1000 ° C. This fuel cell power generation system using a solid oxide fuel cell is prosperous as a promising power generation technology because it can generate power with particularly high efficiency compared to other fuel cell power generation systems and gas engines. Research and development is being carried out in.

By the way, in a fuel cell power generation system, one of the means for improving the power generation efficiency is known as a means for improving the fuel ratio (fuel utilization rate) used for power generation in the fuel gas generated in the reforming section. By improving the fuel utilization rate, the amount of raw fuel gas to be input can be reduced and the power generation efficiency can be improved.

In addition, as the raw material and fuel gas, city gas supplied by a gas company is often used. Normally, the gas company adjusts the calorific value of the city gas to a value such as 45 MJ and then supplies it to the consumer, and the raw material fuel gas of the calorific value is supplied to the reforming section. Then, by supplying the reforming portion with a predetermined flow rate of reforming water determined according to the flow rate of the raw fuel gas having the calorific value, the reforming unit is supplied under the optimum S / C value (steam / carbon ratio). Steam reforming of fuel gas is performed. If the S / C value is too small, the durability of the cell stack is lowered due to carbon precipitation or the like, and if the S / C value is too large, the power generation efficiency is lowered.

As one of the solutions to such a problem, for example, a fuel cell system disclosed in Patent Document 1 has been proposed. The fuel cell system disclosed in Patent Document 1 is made in view of the fact that the fuel utilization rate and the S / C ratio fluctuate due to the fluctuation of the calorific value due to the fluctuation of the composition of the raw material and fuel gas, and the above-mentioned problems occur. It is equipped with a calorific value detecting means for detecting the calorific value of the raw material fuel gas, and controls the flow rate of the raw material fuel gas according to the calorific value of the raw material fuel gas detected by the calorific value detecting means to utilize the fuel. It suppresses fluctuations in the rate and S / C value and keeps them constant.

Japanese Patent No. 5770622

By the way, the auxiliary equipment used for the gas flow meter that measures the flow rate of the raw fuel gas of the fuel cell power generation system has variations during manufacturing, etc., due to such variations in the auxiliary equipment. , The actual gas flow rate of raw material and fuel gas varies. Specifically, although the gas flow rate measured by the gas flow meter and the target gas flow rate seem to match, the actual gas flow rate has an error on the side larger or smaller than the measured gas flow rate. It becomes a state.

Therefore, considering the variation during manufacturing of the gas flow meter, it is necessary to control the flow rate of the raw material and fuel gas so that the flow rate has a certain safety margin, which improves the fuel utilization rate. There is a limit.

In addition, if the fuel cell power generation system is operated for a long time with an error between the measured gas flow rate and the actual gas flow rate due to variations in the manufacturing of the gas flow meter, the amount of reforming water supplied. On the other hand, there are problems that the supply amount of raw material and fuel gas becomes excessive or insufficient, the cell stack deteriorates or fails, and the power generation cost rises due to the excessive consumption of raw material and fuel gas. be.

However, the fuel cell system of Patent Document 1 does not consider the error between the measured gas flow rate and the actual gas flow rate due to variations in the manufacturing of the gas flow meter, and cannot solve the above problem.

The present invention has been made in view of the above circumstances, and it is possible to correct an error between the measured gas flow rate and the actual gas flow rate due to variations in the manufacturing of the gas flow meter, and the raw fuel gas is appropriate. It is an object of the present invention to provide a fuel cell power generation system that can be supplied by a flow rate.

The characteristic configuration of the fuel cell power generation system according to the present invention for achieving the above object is a reforming section for steam reforming raw fuel gas to generate fuel gas, and a fuel gas generated by the reforming section. A cell stack with multiple fuel cell cells to generate power using is provided inside the container.
A fuel supply means for supplying the raw material and fuel gas to the reforming unit,
An internal temperature sensor that measures the temperature of a predetermined part in the container,
A control device for controlling the operation of the fuel supply means is provided.
The fuel supply means includes a gas flow rate measuring unit and a gas supply unit whose operation is controlled by the control device based on the flow rate measured by the gas flow rate measuring unit.
The control device controls the operation of the gas supply unit based on the measured gas flow rate measured by the gas flow rate measuring unit in a state where the temperature inside the container has risen to a predetermined temperature rise target temperature. A fuel cell power generation system that supplies raw fuel gas at a predetermined flow rate and performs power generation operation to generate power in the cell stack.
The control device is
Before performing the power generation operation, the operation of the gas supply unit is controlled so that the measured gas flow rate of the gas flow rate measuring unit becomes constant in a state of apparently matching a predetermined reference gas flow rate, and the internal temperature sensor is used. A temperature rise step of raising the measured temperature of the above temperature to the temperature rise target temperature is carried out, and the temperature rise rate in a predetermined temperature range during the temperature rise step is calculated.
Using the calculated temperature rise rate, a flow rate correction coefficient for correcting an error between the measured gas flow rate of the gas flow rate measuring unit and the actual gas flow rate is determined.
The point is to control the operation of the gas supply unit based on the corrected gas flow rate obtained by multiplying the measured gas flow rate of the gas flow rate measuring unit by the flow rate correction coefficient.

The presence or absence of an error between the measured gas flow rate and the actual gas flow rate due to variations in the manufacturing of the gas flow rate measuring unit and the magnitude of the error appear as a difference in the temperature rise rate. That is, even if the raw fuel gas is supplied so that the measured gas flow rate is in a state of apparently matching with the reference gas flow rate and is constant, the measured gas flow rate is compared with the case where there is no error between the measured gas flow rate and the actual gas flow rate. Is smaller than the actual gas flow rate, the time required for the temperature of a predetermined part in the container to rise to the temperature rise target temperature becomes shorter and the temperature rise rate becomes faster, while the measured gas flow rate is higher than the actual gas flow rate. The larger the value, the longer it takes for the temperature of a predetermined portion in the container to rise to the temperature rise target temperature, and the slower the temperature rise rate.

According to the above characteristic configuration, the flow rate correction coefficient is determined using the presence or absence of an error between the measured gas flow rate and the actual gas flow rate and the temperature rise rate that changes depending on the magnitude, and the flow rate is corrected to the measured gas flow rate of the gas flow rate measuring unit. The corrected gas flow rate is calculated by multiplying by the coefficient and corrected for the error between the actual gas flow rate, and the control device controls the operation of the gas supply unit based on the corrected gas flow rate. That is, even if there are variations in the auxiliary machinery that make up the gas flow rate measuring unit during manufacturing and there is an error between the measured gas flow rate and the actual gas flow rate, the control device can use the flow rate corrected for this error. Since the operation of the gas supply unit can be controlled, the raw fuel gas can be supplied to the reforming unit at an appropriate flow rate. Therefore, the fuel utilization rate can be further improved, and deterioration of the cell stack, occurrence of failure, and increase in power generation cost due to excess or deficiency of fuel gas can be suppressed.

Further, a further characteristic configuration of the fuel cell power generation system according to the present invention further includes a storage device.
The control device is
The calculated temperature rise rate and the reference temperature stored in advance in the storage device and when the measured temperature of the internal temperature sensor rises to the temperature rise target temperature when the raw material fuel gas is supplied at the reference gas flow rate. Calculate the temperature rise rate difference from the rise rate,
A point of determining the flow rate correction coefficient according to the calculated temperature rise rate difference by referring to a flow rate correction coefficient map stored in advance in the storage device and defining the relationship between the temperature rise rate difference and the flow rate correction coefficient. It is in.

In the above characteristic configuration, the reference temperature rise rate is the rate at which the measurement temperature of the internal temperature sensor rises to the temperature rise target temperature when the raw fuel gas is supplied at the reference gas flow rate, and the raw fuel gas is used as the reference gas. The case where the gas is supplied at the flow rate corresponds to the case where the measured gas flow rate and the actual gas flow rate match (there is no error). That is, the difference between the reference temperature rise rate and the temperature rise rate (temperature rise rate difference) corresponds to the error between the measured gas flow rate and the actual gas flow rate.

Therefore, according to the above feature configuration, a flow rate correction coefficient map that defines the relationship between the temperature rise rate difference corresponding to the error between the measured gas flow rate and the actual gas flow rate and the flow rate correction coefficient is created in advance and stored in the storage device. Then, determine the flow rate correction coefficient according to the calculated temperature rise rate difference, multiply this by the measured gas flow rate, calculate the corrected gas flow rate that corrects the error with the actual gas flow rate, and calculate the corrected gas flow rate. Based on this, the control device controls the operation of the gas supply unit. Therefore, similarly to the above, even if there is an error between the measured gas flow rate and the actual gas flow rate, the control device can control the operation of the gas supply unit based on the flow rate corrected for this error. Fuel gas can be supplied to the reforming section at an appropriate flow rate, the fuel utilization rate can be further improved, cell stack deterioration and failure occur due to excess and deficiency of fuel gas, and power generation cost increases. Can be suppressed.

Further, a further characteristic configuration of the fuel cell power generation system according to the present invention is that the predetermined temperature range during the temperature rise step is 50 to 90% of the temperature rise target temperature.

Here, when the speed from the time when the temperature inside the container is about the same as the temperature outside the container (outside air temperature) to the temperature rise to a predetermined temperature is defined as the temperature rise rate, the temperature rise rate is the measured gas. In addition to the error between the flow rate and the actual gas flow rate, the influence of the outside air temperature is taken into consideration. Therefore, from the viewpoint of correcting the error between the measured gas flow rate and the actual gas flow rate, the temperature inside the container is sufficiently higher than the outside air temperature so that the influence of the outside air temperature is extremely small at the temperature rise rate. It is preferable that the speed is in the range of rising from the point in time to a predetermined temperature.

The temperature rise target temperature is a temperature at which power generation operation is possible (for example, 700 to 1000 ° C.). According to the above characteristic configuration, the temperature at which the measured temperature of the internal temperature sensor (the temperature of a predetermined part in the container) rises from a temperature sufficiently higher than the outside air temperature to a predetermined temperature is the temperature rise rate, and the temperature rise rate is the same. However, the influence of the outside air temperature becomes extremely small. Therefore, according to the flow rate correction coefficient determined by using the temperature rise rate, the error between the measured gas flow rate and the actual gas flow rate can be corrected more accurately.

It is a schematic block diagram of the fuel cell power generation system which concerns on 1st Embodiment. It is a flowchart explaining the flow rate correction coefficient determination process which concerns on 1st Embodiment. It is a graph explaining the difference in the temperature rise rate. It is a graph explaining the flow rate correction coefficient.

[First Embodiment]
Hereinafter, the fuel cell power generation system 1 according to the first embodiment will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a fuel cell power generation system using a solid oxide fuel cell. As shown in the figure, the fuel cell power generation system 1 includes a reforming unit 2 that steam reforms raw fuel gas to generate fuel gas, a vaporization unit 3 connected to the reforming unit 2, and a reforming unit 2. A cell stack 4 having a plurality of fuel cell Fs that generate power using the fuel gas generated in the cell stack 4 and a combustion unit 7 that burns off gas from the cell stack 4 are provided in the high temperature container 10 and the vaporization unit 3 is provided. A fuel supply means 11 that supplies raw fuel gas at a predetermined flow rate, a reforming water supply means 15 that supplies reforming water to the vaporization unit 3, and an air supply means 20 that supplies air into the high temperature container 10 at a predetermined flow rate. The cell stack 4 includes a power conversion unit 25 that converts the power generated in the cell stack 4 into power having a desired voltage, frequency, and phase, and a control device 30 that controls the operation.

The raw fuel gas is supplied to the vaporization unit 3 through the raw fuel gas flow path L1, and the reforming water used for steam reforming in the reforming unit 2 is supplied through the reforming water flow path L2. The vaporizing unit 3 heats the supplied reforming water using the combustion heat transmitted from the combustion unit 7 and evaporates it. Further, in the vaporization unit 3, the generated steam and the raw fuel gas are also mixed, and the mixed gas is supplied to the reforming unit 2 through the mixed gas flow path L3.

A gas flow meter 12, a gas blower 13, and a control valve (not shown) as the fuel supply means 11 are provided in the middle of the raw fuel gas flow path L1. As the gas flow meter 12, a thermal mass flow meter that measures by utilizing the heat diffusion action of raw materials and fuel is used. Further, in the raw material / fuel gas flow path L1 on the downstream side of the gas blower 13, for example, a desulfurizer (not shown) for removing the sulfur compound contained in the raw material / fuel gas is provided. By the operation of the gas blower 13 and the control valve, the raw fuel gas is supplied into the vaporization unit 3 through the raw fuel gas flow path L1. The gas flow meter 12 measures the gas flow rate per unit time of the raw fuel gas supplied to the vaporization unit 3, and the measurement result is transmitted to the control device 30 and stored in the storage device 31. Further, the operation of the gas blower 13 and the control valve is controlled by the control device 30. In the present embodiment, the gas flow meter 12 corresponds to the "gas flow rate measuring unit", and the gas blower 13 and the control valve correspond to the "gas supply unit".

A reforming water pump 16 and a reforming water tank 17 as a reforming water supply means 15 are provided in the middle of the reforming water flow path L2, and the reforming water pump 16 operates to reform the reforming water. The reforming water stored in the tank 17 flows through the reforming water flow path L2 and is supplied into the vaporization unit 3. The operation of the reforming water pump 16 is controlled by the control device 30.

A mixed gas of the raw material fuel gas and steam obtained in the vaporization unit 3 is supplied to the reforming unit 2. Then, in the reforming unit 2, steam reforming of the raw material fuel gas is performed to generate a fuel gas containing hydrogen as a main component. Further, the combustion heat generated in the combustion unit 7, which will be described later, is transmitted to the reforming unit 2, and the heat promotes the reforming reaction. The fuel gas generated by the reforming unit 2 is supplied to the manifold 5 of the cell stack 4, which will be described later, through the fuel gas flow path L4.

The cell stack 4 has a fuel flow section (not shown) through which the fuel gas generated in the reforming section 2 passes, and an air flow section through which air (that is, an oxidant (oxygen)) passes. A plurality of solid oxide fuel cell Fs provided are provided in a state of being electrically connected in series. Although not shown, the fuel cell F is configured in the form of a solid oxide having a solid electrolyte layer between the fuel electrode and the air electrode. In each fuel cell F, the fuel gas is supplied to the entire fuel electrode by allowing the fuel gas to pass upward through the fuel passage section, and the air is passed upward through the air passage section to allow the air electrode to flow upward. Air is supplied to the whole.

In addition, a manifold 5 for receiving fuel gas supplied from the reforming unit 2 through the fuel gas flow path L4 is provided in the lower part of the cell stack 4. The plurality of fuel cell Fs are arranged so as to be lined up on the upper side of the manifold 5, and the manifold 5 and the gas introduction port (not shown) at the lower end of the fuel flow portion in the plurality of fuel cell Fs are communicately connected to each other. ing. Then, the fuel gas supplied to the manifold 5 is supplied from the gas introduction port at the lower end to each fuel passage portion of the plurality of fuel cell F, and each fuel passage portion is passed from the lower side to the upper side. Is used for the power generation reaction. After being subjected to the power generation reaction, the discharged fuel gas is discharged from the fuel gas discharge port (not shown) at the upper end.

The high temperature container 10 is provided with an air introduction section 6, and an air supply flow path L5 through which air flows is connected to the air introduction section 6. An air filter 21, an air blower 22 and an air flow meter 23 as an air supply means 20 are provided in the middle of the air supply flow path L5, and the operation of the air blower 22 causes air to pass through the air supply flow path L5 to the high temperature container 10. Supplied within. The air filter 21 is provided to catch foreign matter such as dust in the air sucked into the air supply flow path L5 by the air blower 22 and prevent the foreign matter from entering the high temperature container 10. Further, the air flow meter 23 measures the flow rate per unit time supplied into the high temperature container 10, and the measurement result of the air flow meter 23 is transmitted to the control device 30 and stored in the storage device 31. The operation of the air blower 22 is controlled by the control device 30.

In the vicinity of the lower end of the air flow section in each of the plurality of fuel cell Fs, an air supply hole (not shown) for communicating the inside of the high temperature container 10 and the air flow section is provided, and the air flow section is provided. Is supplied with air in the high temperature container 10 through an air supply hole, and flows downward through each air flow section to be subjected to a power generation reaction. Then, the exhaust air after being subjected to the power generation reaction is discharged from the air outlet (not shown) at the upper end.

Further, above the cell stack 4 in the high temperature container 10, off gas (that is, exhaust gas discharged from the fuel flow section of each fuel cell F and exhaust air discharged from the air flow section (that is, oxygen). )) Is fueled, and a combustion space (that is, a combustion unit 7) is formed. That is, the combustion unit 7 is realized by the cell stack 4. Further, an igniter 8 is also provided in this combustion space (combustion unit 7). In addition, the vaporization unit 3 and the reforming unit 2 are provided adjacent to the combustion space above the cell stack 4. As a result, as described above, the vaporization unit 3, the reforming unit 2, and the cell stack 4 are heated by the combustion heat generated in the combustion unit 7.

Further, the high temperature container 10 is formed with an exhaust gas portion 9 formed on the lower surface portion or the like to discharge the combustion exhaust gas generated in the combustion portion 7 to the outside, and is in the combustion exhaust gas discharged to the outside from the exhaust gas portion 9. A combustion catalyst unit 9a (for example, a platinum-based catalyst) for removing carbon monoxide gas and the like is provided.

In the high temperature container 10, three temperature sensors T1, T2, T3 as internal temperature sensors for measuring the temperature of a predetermined portion in the high temperature container 10 are provided, and measurement by these temperature sensors T1, T2, T3 is provided. The result is transmitted to the control device 30 and stored in the storage device 31. The temperature sensor T1 measures the temperature in the vicinity of the combustion unit 7, and the measurement result is used for determining whether or not the combustion in the combustion unit 7 is properly performed. Further, the temperature sensor T2 measures the temperature inside the high temperature container 10, for example, the temperature on the side of the cell stack 4. Further, the temperature sensor T3 measures the temperature of the reforming unit 2 (for example, the temperature of the reforming catalyst), and the measurement result is used for determining whether or not the temperature of the reforming unit 2 is appropriate.

The power conversion unit 25 is an inverter or the like electrically connected to the cell stack 4. Then, the electric power generated by the cell stack 4 is supplied to various electric load devices, electric power systems, and the like via the electric power line 26 connected to the electric power conversion unit 25.

The control device 30 is a device configured by using an electric circuit unit having an arithmetic processing function such as a microcomputer, and is a storage device 31 configured by using an electric circuit unit having an information storage function such as a semiconductor memory. It exchanges data as appropriate and executes a predetermined process.

According to the fuel cell power generation system 1 having the above configuration, the control device 30 supplies the raw material / fuel gas to the reforming unit 2 (vaporization unit 3) so that the flow rate per unit time is constant, and at the same time, the raw material / fuel gas is supplied. After supplying reforming water corresponding to the supply amount of fuel gas to the reforming section 2 (vaporization section 3) and performing a temperature raising step of raising the temperature inside the high temperature container 10 to a predetermined target temperature by burning the fuel gas. , Performs power generation operation using an electrochemical reaction in the cell stack 4.

By the way, during power generation operation, in order to improve the fuel utilization rate and prevent deterioration of the cell stack 4 due to excess or deficiency of fuel gas, the flow rate of the raw fuel gas supplied to the reforming unit 2 (vaporization unit 3) is adjusted. It is important to control as strictly as possible, and in the fuel cell power generation system 1, the flow rate of the raw fuel gas is measured by the gas flow meter 12, and the flow rate of the raw fuel gas is timely and predetermined based on the measurement result. The control device 30 controls the operation of the gas blower 13 and the control valve so as to have a flow rate.

However, since accessories such as the gas flow meter 12 have variations during manufacturing, the gas flow rate (measured gas flow rate) measured by the gas flow meter 12 and the actual gas flow rate are based on the variations. There is an error with (actual gas flow rate). Specifically, even if the gas flow rate measured by the gas flow meter 12 apparently matches the predetermined target gas flow rate, the actual gas flow rate may be larger or smaller than the measured gas flow rate. Therefore, if the operations of the gas blower 13 and the control valve are controlled based on the measured gas flow rate, excess or deficiency of the actual gas flow rate with respect to the originally required gas flow rate occurs.

Therefore, in the fuel cell power generation system 1 according to the present embodiment, in order to perform power generation operation while correcting an error between the measured gas flow rate and the actual gas flow rate due to variations during manufacturing of the gas flow meter 12, the following Perform the process shown in.

Specifically, first, a process of determining a flow rate correction coefficient for correcting an error between the measured gas flow rate and the actual gas flow rate is performed. FIG. 2 is a flowchart illustrating a flow rate correction coefficient determination process. In the flow rate correction coefficient determination process, first, as described above, when the power generation operation is performed, the control device 30 makes sure that the measured gas flow rate of the gas flow meter 12 is constant in a state of matching a predetermined reference gas flow rate. A temperature raising step for controlling the operation of the gas blower 13 and the control valve is carried out (step # 1). Then, the control device 30 determines whether or not the temperature measured by the temperature sensor T2 (the temperature inside the high temperature container 10) has reached a predetermined temperature rise target temperature (step # 2), and reaches the temperature rise target temperature. If it is determined that the product has been reached, the process proceeds to step # 3. Step # 2 is repeated until it is determined that the temperature rise target temperature has been reached. Further, the temperature and elapsed time in the high temperature container 10 in the temperature raising step are sequentially stored in the storage device 31.

Here, as described above, there may be an error between the measured gas flow rate and the actual gas flow rate. In that case, even if the operations of the gas blower 13 and the control valve are controlled based on the measured gas flow rate, the time until the temperature inside the high temperature container 10 rises to a predetermined temperature changes due to the influence of the above error. This will be specifically described with reference to FIG. FIG. 3 shows the operation of the gas blower 13 and the control valve controlled so that the measured gas flow rates of the three different gas flow meters 12 (individuals A, B, and C) are constant in a state of apparently matching the predetermined reference gas flow rates. It is a graph which showed the relationship between the time and the temperature when the temperature in the high temperature container 10 was raised from 350 degreeC to 700 degreeC. The gas flow rate measured by the individual A has no error with the actual gas flow rate, the gas flow rate measured by the individual B is smaller than the actual gas flow rate, and the gas flow rate measured by the individual C is larger than the actual gas flow rate. It shall be.

In this case, even if the measured gas flow rate of each gas flow meter 12 apparently matches the reference gas flow rate, the actual gas flow rate will be different. As shown in FIG. 3, when the individual B is used, the measured gas flow rate is smaller than the actual gas flow rate, so that the actual gas flow rate is larger than when the individual A whose measured gas flow rate and the actual gas flow rate match is used. The temperature rise rate becomes faster. On the other hand, when the individual C is used, the measured gas flow rate is larger than the actual gas flow rate, so that the actual gas flow rate is smaller and the temperature rise rate is slower than when the individual A is used.

As described above, the error between the gas flow rate measured by the gas flow meter 12 and the actual gas flow rate appears as a difference in the temperature rise rate. Therefore, in the fuel cell power generation system 1 of the present embodiment, in step # 3, the control device 30 is in the high temperature container 10 based on the information regarding the temperature and the elapsed time in the high temperature container 10 stored in the storage device 31. The speed (temperature rise rate) in a predetermined temperature range until the temperature rises to the temperature rise target temperature is calculated and stored in the storage device 31, and the process proceeds to step # 4.

When the temperature from the time when the temperature inside the high temperature container 10 is about the same as the temperature outside the high temperature container 10 (outside air temperature) to the temperature rise to a predetermined temperature is taken as the temperature rise rate, the temperature rise rate is Not only the error between the measured gas flow rate and the actual gas flow rate, but also the influence of the outside air temperature is taken into consideration. Therefore, from the viewpoint of correcting the error between the measured gas flow rate and the actual gas flow rate, the temperature inside the high temperature container 10 is sufficiently higher than the outside air temperature so that the influence of the outside air temperature is extremely small in the temperature rise rate. It is preferable to calculate based on the temperature rise value in the range where the temperature rises from the time when the temperature rises to a predetermined temperature and the time required for the temperature rise. Therefore, in the present embodiment, the temperature rise rate is the temperature rise value and the time required for the temperature rise when the temperature is raised from 50% to 90% of the temperature rise target temperature (700 ° C.) which is sufficiently higher than the outside air temperature. Calculated based on. If the temperature is within the range of 50% to 90% of the temperature rise target temperature, it is not always necessary to use the temperature rise rate when the temperature is raised from 50% to 90%, and the temperature rises from 70% to 80%, for example. It can also be used by measuring the temperature rise rate during that period.

Then, in step # 4, the control device 30 calculates the temperature rise rate difference obtained by subtracting the reference temperature rise rate stored in the storage device 31 from the temperature rise rate, and shifts to step # 5. The reference temperature rise rate is the rate at which the temperature inside the high temperature container 10 rises from a predetermined temperature to the temperature rise target temperature when the raw fuel gas is accurately supplied at the reference gas flow rate, and is used for fuel cell power generation. It is stored in the storage device 31 in advance at the manufacturing stage of the system 1. In the present embodiment, a soap film type flow meter capable of measuring the gas flow rate extremely accurately is used, and the temperature rises when the temperature inside the high temperature container 10 rises from 350 ° C to the temperature rise target temperature of 700 ° C. The temperature rise rate calculated based on the value and the time required for the temperature rise is used as the reference temperature rise rate. Further, in Table 1, the temperature rise rate Vta, Vtb, Vtc, the reference temperature rise rate Vt, and the temperature rise rate are taken as an example when the above-mentioned three different gas flow meters 12 (individuals A, B, C) are used. The differences ΔVta, ΔVtb, and ΔVtc are shown.

In step # 5, the control device 30 refers to the flow rate correction coefficient map (graph defining the relationship between the temperature rise rate difference and the flow rate correction coefficient) shown in FIG. 4, and the flow rate correction according to the calculated temperature rise rate difference. The coefficient is determined and stored in the storage device 31. The flow rate correction coefficient map created in advance based on experimental data, calculation results, and the like is stored in the storage device 31.

For example, when the above-mentioned three different gas flow meters (individuals A, B, and C) are used as an example and described with reference to FIG. 4, the individual A in which the measured gas flow rate and the actual gas flow rate match will be described. Since the temperature rise rate difference ΔVta is 0 and it is not necessary to substantially correct the measured gas flow rate, the flow rate correction coefficient is 1. On the other hand, for the individual B whose measured gas flow rate is smaller than the actual gas flow rate, the temperature rise rate difference ΔVtb is positive (that is, the temperature rise rate Vtb is faster than the reference temperature rise rate Vt), and the measurement is performed. The flow rate correction coefficient for correcting the error between the gas flow rate and the actual gas flow rate is less than 1. Further, for the individual C whose measured gas flow rate is larger than the actual gas flow rate, the temperature rise rate ΔVtc is negative (that is, the temperature rise rate Vtc is slower than the reference temperature rise rate Vt), and the measured gas flow rate and the actual gas flow rate. The flow rate correction coefficient for correcting the error with the gas flow rate exceeds 1.

Then, in the power generation operation, the control device 30 controls the operation of the gas blower 13 and the control valve based on the corrected gas flow rate obtained by multiplying the measured gas flow rate of the gas flow meter 12 by the flow rate correction coefficient stored in the storage device 31. ..

As described above, according to the fuel cell power generation system 1 according to the present embodiment, the flow rate correction coefficient determination process is performed to correct the error between the gas flow rate measured by the gas flow rate meter 12 and the actual gas flow rate. The flow rate correction coefficient can be determined, and the control device 30 controls the gas blower 13 based on the corrected gas flow rate obtained by multiplying the measured gas flow rate of the gas flow meter 12 by the flow rate correction coefficient. That is, even if there are variations in the auxiliary machinery constituting the gas flow meter 12 during manufacturing and there is an error between the measured gas flow rate and the actual gas flow rate, the control device 30 is based on the flow rate corrected for this error. Can control the operation of the gas blower 13 and the control valve, so that the raw fuel gas can be supplied to the reforming unit 2 (vaporization unit 3) at an appropriate flow rate. Therefore, the fuel utilization rate can be increased, and deterioration and failure of the cell stack 4 due to excess or deficiency of fuel gas can be suppressed.

[Another Embodiment]
[1] In the above embodiment, the configuration of the fuel cell power generation system 1 has been described with specific examples, but the configuration can be changed as appropriate. For example, in the above embodiment, the temperature rise rate is calculated based on the temperature rise value in the range of 50% to 90% of the temperature rise target temperature and the time required for the temperature rise. Not limited. That is, it may be calculated based on the temperature rise value in an arbitrary temperature range in which the temperature rises linearly and the time required for the temperature rise.

[2] Further, in the above embodiment, the flow rate correction coefficient is determined by using the temperature rise rate of the measured temperature (temperature in the high temperature container 10) of the temperature sensor T2, but the present invention is not limited to this. .. For example, the measured temperature of the temperature sensor T1 (the temperature near the combustion unit 7) and the measured temperature of the temperature sensor T3 (the temperature of the reforming unit 2) also correspond to the temperature inside the high temperature container 10, and the gas flow meter 12 Since it is affected by the error between the measured gas flow rate and the actual gas flow rate, the flow rate correction coefficient may be determined by using the temperature rise rate of the measured temperature of each of the temperature sensors T1 and T2.

[3] Further, the flow rate correction coefficient determination process in the above embodiment can be performed at any timing. For example, it may be performed every time the fuel cell power generation system 1 is started, or it may be performed when the fuel cell power generation system 1 is first started after a predetermined start time has elapsed since the flow rate correction coefficient determination process was last performed. It may be performed when the number of activations after the flow rate correction coefficient determination process reaches a predetermined number of times.

The configuration disclosed in the above embodiment (including another embodiment, the same shall apply hereinafter) can be applied in combination with the configuration disclosed in other embodiments as long as there is no contradiction. The embodiments disclosed in the present specification are examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified without departing from the object of the present invention.

INDUSTRIAL APPLICABILITY The present invention is a fuel cell power generation system capable of correcting an error between a measured gas flow rate and an actual gas flow rate due to variations during manufacturing of a gas flow meter and supplying raw fuel gas at an appropriate flow rate. Can be used for.

1 Fuel cell power generation system 2 Remodeling unit 4 Cell stack 7 Combustion unit 10 High temperature container 11 Fuel supply means 12 Gas flow system 13 Gas blower 30 Control device C Fuel cell cells T1, T2, T3 Temperature sensor

Claims (3)

A reforming unit that steam reforms the raw fuel gas to generate fuel gas and a cell stack having a plurality of fuel cell cells that generate power using the fuel gas generated by the reforming unit are provided inside the container. ,
A fuel supply means for supplying the raw material and fuel gas to the reforming unit,
An internal temperature sensor that measures the temperature of a predetermined part in the container,
A control device for controlling the operation of the fuel supply means is provided.
The fuel supply means includes a gas flow rate measuring unit and a gas supply unit whose operation is controlled by the control device based on the flow rate measured by the gas flow rate measuring unit.
The control device controls the operation of the gas supply unit based on the measured gas flow rate measured by the gas flow rate measuring unit in a state where the temperature inside the container has risen to a predetermined temperature rise target temperature. A fuel cell power generation system that supplies raw fuel gas at a predetermined flow rate and performs power generation operation to generate power in the cell stack.
The control device is
Before performing the power generation operation, the operation of the gas supply unit is controlled so that the measured gas flow rate of the gas flow rate measuring unit becomes constant in a state of apparently matching a predetermined reference gas flow rate, and the internal temperature sensor is used. A temperature rise step of raising the measured temperature of the above temperature to the temperature rise target temperature is carried out, and the temperature rise rate in a predetermined temperature range during the temperature rise step is calculated.
Using the calculated temperature rise rate, a flow rate correction coefficient for correcting an error between the measured gas flow rate of the gas flow rate measuring unit and the actual gas flow rate is determined.
A fuel cell power generation system that controls the operation of the gas supply unit based on the corrected gas flow rate obtained by multiplying the measured gas flow rate of the gas flow rate measuring unit by the flow rate correction coefficient. With more storage
The control device is
The calculated temperature rise rate and the reference temperature stored in advance in the storage device and when the measured temperature of the internal temperature sensor rises to the temperature rise target temperature when the raw material fuel gas is supplied at the reference gas flow rate. Calculate the temperature rise rate difference from the rise rate,
A request for determining the flow rate correction coefficient according to the calculated temperature rise rate difference by referring to a flow rate correction coefficient map stored in advance in the storage device and defining the relationship between the temperature rise rate difference and the flow rate correction coefficient. Item 1. The fuel cell power generation system according to Item 1. The fuel cell power generation system according to claim 1 or 2, wherein the predetermined temperature range during the temperature rise step is 50 to 90% of the temperature rise target temperature.

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