JPH0676846A - Operation control device for fuel cell power generating device - Google Patents

Abstract

PURPOSE:To provide an operation control device improving the responsiveness of the raw material and combustion air when a load is abruptly changed in a fuel cell power generating device. CONSTITUTION:An operation control device is provided with a load detector 71, a switching unit 72, and a second arithmetic unit 74 determining the opening difference between regulating valves V1, V2 based on the change quantity of a load. When the load is abruptly changed, the openings of the regulating valves V1, V2 corresponding to the load change are added to the present openings, and the responsiveness of the gas flow is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for a fuel cell power generator, and more particularly to control of the flow rates of a reforming raw material and combustion air when the load suddenly changes.

[0002]

2. Description of the Related Art FIG. 12 shows, for example, JP-A-62-29868.
2 shows a conventional fuel cell power generation system disclosed in Japanese Patent Publication No.
In the figure, 50 is a reformer as a fuel processor having a burner section 51, V1 is a raw material supply control valve, Q1 is a raw material flow rate measuring section, and C1 is a raw material flow rate controller. Similarly, V
1, Q2 and C2 are a steam control valve, a flow rate measuring unit and a flow rate controller, respectively. Reference numeral 10 is a fuel cell, 11 is a fuel chamber, and 12 is an air chamber. An output control calculation unit 70 calculates and outputs a set value of the raw material gas using a signal relating to the electric load of the fuel cell 10 as an input.

Next, the operation will be described. When city gas is used as the raw material gas, the city gas contains a sulfur compound that reduces the activity of the reforming catalyst as an odorant.Therefore, a desulfurization reactor for removing this and a reformer The carbon monoxide transformer for transforming carbon monoxide contained in the gas reformed in step (hereinafter referred to as reformed gas) into carbon dioxide is required, but this is omitted in FIG. To do.

Hydrogen and oxygen which are fuels of the fuel cell 10 are
They are supplied as reformed gas and air, respectively. The raw materials for the reforming reaction are city gas and steam, and the city gas controlled by the raw material flow rate control valve V1 and the steam controlled by the steam flow rate control valve V2 are mixed to form the reformer 5
0, and becomes the fuel gas for the fuel cell 10.

This fuel gas is supplied to the fuel chamber 11 of the fuel cell 10 through the fuel flow rate control valve 13. Fuel chamber 1
The fuel exhaust gas leaving 1 is reformer 5 as a fuel processing device.
0 is sent to the burner section 51 and burned as a heat source necessary for the reforming reaction.

The flow rate of the raw material gas and the flow rate of the air are calculated by the output control calculation unit 70 based on the output of the fuel cell 10 and are obtained. This calculation can be performed based on the battery output, hydrogen utilization rate, air utilization rate, methane decomposition rate, and the like. The flow rate setting value S0 obtained by the output control calculation unit 70 is sent to the flow rate controllers C1, C2, C3 at the same time to control the amount of each gas.

For example, in the case of the raw material gas, the raw material gas flow rate adjusting section C1 compares the given flow rate set value with the measured value detected by the flow rate measuring section Q1 so that the deviation becomes zero. The opening degree of the flow rate control valve V1 is controlled. By always performing this control, the gas required for the fuel cell 10 can be supplied. The flow rate control of steam and fuel gas is the same as the control of raw material gas.

[0008]

Since the conventional fuel cell system is configured as described above, the fuel cell 10
Since the control for adjusting the flow rate of each gas to the set value will be performed even when the load of No. 2 suddenly changes, the operation of stabilizing the control delays the opening / closing operation of the control valves V1, V2, V3, and It caused shortages or excesses.

Further, the fuel gas control valve V is used for controlling the fuel gas.
Raw gas (city gas, steam)
Control and double control, resulting in a complicated configuration.

The present invention has been made in order to solve the above problems, and it is possible to control the flow rate control valve so that the raw material gas can flow at the required flow rate to the battery even when the load changes rapidly. The purpose of the present invention is to obtain a device with a simple structure by reducing the flow rate control system, and to obtain an operation control device for a fuel cell power generator in which the temperature change of the reformer is small and the structure is simple. Is intended.

[0011]

According to a first aspect of the present invention, there is provided an operation control device for a fuel cell power generation device for reforming a mixed gas, the flow rate of which is controlled by a raw material gas control valve and a steam control valve. Unit, a fuel cell that receives the supply of the fuel gas reformed by the reformer to generate electricity, an orthogonal converter that converts the DC output of the fuel cell into an AC and supplies the AC load to a load, and the orthogonal converter In the operation control device of the fuel cell power generator including the control means for controlling the opening degree of each of the control valves based on the output and the set value given, the sudden change of the load based on the output of the orthogonal conversion device. A load detection unit for detecting the load and a correction control unit for correcting and controlling the opening by giving a difference in the opening of each control valve according to the change when the load sudden change is detected by the load detection unit.

An operation control device for a fuel cell power generator according to a second aspect of the present invention includes a reformer for reforming a mixed gas whose flow rate is controlled by a raw material gas control valve and a steam control valve.
A combustion air control valve that controls the supply of combustion air to the burner of the reformer, a fuel cell that receives the fuel gas reformed by the reformer to generate electricity, and a DC output of the fuel cell A fuel cell power generator including a quadrature conversion device that converts into alternating current and supplies the load, and control means that controls the opening of each of the control valves based on the output of the quadrature conversion device and a given set value. In the operation control device, a load detection unit that detects a sudden change in load based on the output of the orthogonal transformation device,
When the load detection unit detects a sudden change in the load, a correction control unit is provided for giving a difference in the opening of the combustion air control valve according to the change and correcting and controlling the opening.

Further, an operation control device of a fuel cell power generator according to a third aspect of the present invention is a reformer for reforming a mixed gas whose flow rate is controlled by a raw material gas control valve and a steam control valve, and the reformer. Combustion air control valve for controlling the supply of combustion air to the burner section, a fuel cell for generating power by receiving the supply of the fuel gas reformed by the reformer, and converting the DC output of this fuel cell into AC. Orthogonal transformation device that supplies the load to the load,
In the operation control device of the fuel cell power generation device, which includes the control means for controlling the opening degree of each of the control valves based on the output of the orthogonal conversion device and the given set value, the temperature of the reformer is detected. A temperature detector, a load detection unit that detects a sudden change in the load based on the output of the orthogonal transformation device, and the combustion based on the improved raw material flow rate, the battery current, and the reformer temperature when the load change is detected by the load detection unit. And a correction control means for correcting and controlling the opening degree of the air control valve.

[0014]

According to the first aspect of the present invention, a quick response is possible when the load of the raw material gas flow rate suddenly changes.

Further, according to the second aspect, since the responsiveness of the flow rate control of the combustion air becomes faster, a stable reforming reaction can be obtained.

Further, in claim 3, since the set value of the combustion air is corrected by the flow rate of the raw material and the set value of the reaction tube temperature of the reformer, the temperature of the reformer is further stabilized, and it is suitable for the load. The temperature of the reaction tube can be controlled and a stable system can be constructed.

[0017]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 10 denotes a hydrogen-oxygen type fuel cell, which is composed of a fuel chamber 11, an air chamber 12, electrodes 13 and 14, and an electrolyte impregnated matrix, and an air blower 17 is interposed in the air chamber 12. Is being supplied with air.

Reference numeral 60 is an orthogonal converter for converting the output of the fuel cell 10 into AC power, and 50 is the fuel of the fuel cell 10 by steam reforming the mixed gas whose flow rate is controlled by the raw material gas control valve V1 and the steam control valve V2. It is a reformer that supplies gas to the fuel chamber 11. In FIG. 1, equipment not particularly related to the present invention, such as a desulfurizer and a carbon monoxide shift converter, is omitted.

The exhaust gas from the fuel chamber 11 is recirculated to the burner portion 51 of the reformer 50 and burned by the combustion air supplied from the air blower 17 to serve as a heat source for the reforming reaction.

In the fuel cell power generation system, the hydrogen utilization rate is determined in consideration of the characteristics of the fuel cell 10 and the reforming efficiency in order to obtain high efficiency. By adding this utilization rate and the loss of each device, the flow rates of the city gas and steam, which are the raw materials corresponding to the load of the fuel cell 10, are determined. This flow rate is controlled so that the deviation from the set value is zero with respect to fluctuations and disturbances in the process during stable operation.

However, with respect to a sudden change in load, the raw material and steam flow rates cannot keep up with the proper flow rates due to the dead time and the first-order delay time of control, as shown in FIG. 7 (b). For this reason, the orthogonal transformation device 60 extracts a current commensurate with the load, and the battery voltage decreases as shown in FIG.

The operation with a high hydrogen utilization rate as shown in FIG. 7 (c) leads to deterioration of battery performance. Therefore, it is necessary to control the gas flow rate so that the hydrogen utilization rate is quickly returned to the steady state value.

When the load changes abruptly, the load detector 7
1 detects a sudden change in the load based on the battery current value of the orthogonal transformation device 60 and sends a detection signal to the switch 72. In addition, the second calculator 74 calculates the difference between the battery current value and the previous measured value, and determines the opening according to the load change amount from the function of the control valve opening and the load change amount given in advance. Find and control valves V1, V
The calculated opening is added to the current value of 2, and an opening signal is given to the control valves V1 and V2 via the switch 72.

At this time, the switch 72 receives the detection signal from the load detector 71 when the load changes suddenly so that the output of the second calculator 74 is applied to the control valves V1 and V2 only for a certain period of time after the load changes suddenly. Switch the signal.

FIG. 2 shows details of the above-mentioned raw material flow rate adjustment. In FIG. 2, the orthogonal transformation device 60 sends the battery current value to the load detector 71 and the second computing unit 74.
The second computing unit 74 obtains the difference between the current value of the previous time and the current value of this time, and calculates the opening degree of the control valve corresponding to the difference. Generally, as the control valve, as shown in FIG. 3, it is possible to select one in which the opening V and the flow rate Q of the control valve are linear.
Therefore, the difference between the increased amount of the raw material flow rate and the control valve opening corresponding to the increased amount of the current has the relationship shown in FIG.

As shown in FIG. 5, the second calculator 74 calculates the opening to be opened from the function F of the control valve opening increase / decrease and the current increase / decrease and the current opening. Further, the load detector 71 detects a sudden change in current equal to or greater than the set value, and operates the switch 72 for the set time. Further, the switch 72 applies the control valve opening signal obtained by the second computing unit 74 to the output device 75 only for a certain period of time after the sudden change in the battery current is detected, and keeps the opening of the control valve V1 constant.

The control valve V1 whose opening is maintained can change its flow rate earlier than when it is opened while controlling the flow rate. FIG. 8 shows changes in the flow rate according to this control method. When the set time elapses, the switch 72 outputs the control valve opening by the flow rate control obtained by the first calculator 73 to the output device 7
Give to 5. Therefore, the flow rate is stable, and the flow rate suitable for the load is maintained.

In FIG. 5, a method of directly determining the opening degree instruction value from the current value may be considered, but in this case, after long-term operation, the catalyst of the reformer 50 in the plant is deteriorated or crushed, and the pressure in the system is generally reduced. Therefore, there is a problem in that the same opening function as in the initial operation cannot be used because of the high value.

In the case of this embodiment, the functions are not exactly the same, but the amount of increase or decrease is added to the current opening, so that there is little influence of aging and the amount becomes negligible.

In FIG. 2, each of the first computing unit 73 and the second computing unit 74 is provided with a computation for obtaining the required gas amount from the battery current value. You may put together in.

Example 2. In addition, although the flow rate control of the city gas and the steam, which are the raw materials of the reforming system, has been described in the above-mentioned embodiment, the same control method may be used for the control of the air flow rate given to the air chamber 12 of the fuel cell 10.

FIG. 6 shows the second embodiment. In FIG. 6, V3 is an air flow rate control valve, and Q3 is an air flow meter.
Reference numeral 71 is a load detector, 72 is a switch, 76 is a first arithmetic unit, and 77 is a second arithmetic unit.

The flow rate of air required by the battery can be calculated from the battery current, the air utilization rate and the conversion constant.
During stable operation, flow rate control is performed by the flow rate controller C3 so as to achieve this set value, and when the load changes suddenly, the opening degree obtained by the second computing unit 77 is output via the switch 72 to respond to the flow rate. Improve. The flow rate response is similar to the raw material flow rate response shown in FIG.

Further, FIG. 6 shows a method in which the control valve 13 is inserted downstream of the air blower 17 and the air flow rate is controlled by the opening degree of the control valve. Similar effects can be obtained when controlling the number of revolutions.

Further, in a system in which the air blower 17 is provided with an inverter and a control valve is also used, a set value is set for the air flow rate, and inverter control is performed above the set value, and control valve control and control target below the set value. By dividing, the same effect can be obtained.

Example 3. Next, FIG. 9 shows a combustion air flow rate control according to claim 2 of the present invention. In FIG. 9, as a new configuration, 78 is a first computing unit that obtains the opening of the combustion air control valve V4, 79 is a second computing unit that obtains the opening of the control valve V4 when the load changes suddenly, and 80 is a limit. , Q4 is an air flow rate measuring unit, and C4 is a flow rate controller. Note that FIG. 9 shows the first and second arithmetic units 73 shown in FIG. 1 for simplification of description.
, 74 and the output device 75 are omitted, the flow rate of the raw material gas and steam is controlled by providing these configurations.

The flow rate of the combustion air can be obtained by multiplying the amount of hydrogen in the exhaust gas by subtracting the hydrogen consumption amount of the fuel cell 10 calculated from the cell current from the hydrogen amount obtained from the raw material flow rate by the ratio of the required combustion air. it can. Q _AIR = {Q _H2 −F _H2 (I)} × K × J Q _AIR : Combustion air amount Q _H2 : Hydrogen amount generated by reforming reaction F _H2 (I): Hydrogen consumption amount in fuel cell I: Battery Current K: ratio of required air to hydrogen J: excess air ratio

When the load suddenly changes, the output of the second computing unit 79 is set as the control valve command value by the switching unit 72. A limiter 80 is used for the output of the calculator 79 in order to secure the minimum flow rate of the combustion air. The other relationships between the control valve opening and the flow rate are the same as in the first embodiment.

Therefore, according to the above embodiment, the amount of air corresponding to the amount of hydrogen in the exhaust gas is made to flow quickly, so that the reaction temperature of the reformer 50 does not rise or fall too much, and a stable reforming system is obtained. Can be provided.

Example 4. Next, FIG. 10 shows a combustion air flow rate control according to claim 3 of the present invention. In the third embodiment, it has been shown that the combustion air flow rate is expressed by a function having the air excess ratio as a constant, but in the fourth embodiment, the air excess ratio is modified to reduce the temperature change of the reformer 50. Pawn 50
As a function of the representative temperature of.

In FIG. 10 shown in comparison with FIG. 9,
Reference numeral 90 is a thermometer for measuring the representative temperature of the reformer, and 82 is a third arithmetic unit for obtaining the excess air ratio from the temperature. The flow rate of the output from the thermometer 90 is set by the first calculator 81 and controlled by the controller C4 so that the reformer temperature becomes the set value during stable operation. When the load changes abruptly, the excess air ratio J is calculated by the third calculator 82, and the output is given to the second calculator 79. The processing after the second arithmetic unit is the same as that in the case of claim 2 of the third embodiment.

FIG. 11 shows details of the third arithmetic unit 82.
The difference between the representative temperature of the reformer and the set value is obtained, and the set excess air ratio J _S is multiplied by the ratio having the difference as a function to obtain the excess air ratio J used for the flow rate calculation.

[0043]

As described above, according to the first aspect of the present invention, the control in which the opening corresponding to the set flow rate is added when the load suddenly changes is added to the current opening of the raw material flow rate control valve. Therefore, operation control with good load response becomes possible.

Further, according to the second aspect, by using the opening degree control for the combustion air flow rate control, it becomes possible to perform the operation control in which the temperature change of the reformer is small.

Further, according to the third aspect, since the reformer temperature is corrected in the combustion air flow rate control according to the second aspect, it is possible to further reduce the temperature change of the reformer.

[Brief description of drawings]

FIG. 1 is a system diagram showing a control system according to a first embodiment of the present invention.

FIG. 2 is a system diagram showing the arithmetic unit of FIG.

FIG. 3 is a graph showing the relationship between the control valve opening and the flow rate.

FIG. 4 is a graph showing a flow rate change amount and an opening difference.

FIG. 5 is a flow chart for obtaining an opening degree instruction value from a load change amount.

FIG. 6 is a system diagram showing a control system according to a second embodiment of the first aspect of the present invention.

FIG. 7 is a graph showing a state of flow rate control by a conventional device.

FIG. 8 is a graph showing a state according to the present invention.

FIG. 9 is a system diagram showing a control system according to a third embodiment of the present invention.

FIG. 10 is a system diagram showing a control system according to a fourth embodiment of the present invention.

FIG. 11 is a flowchart showing the calculation of a correction coefficient used in claim 3 of the present invention.

FIG. 12 is a system diagram showing a control system according to a conventional operation control method.

[Explanation of symbols]

 10 Fuel Cell 50 Reformer 51 Berth 60 Orthogonal Transform Device 71 Load Detector 72 Switcher 74 Second Calculator 80 Limiter 82 Third Calculator 90 Temperature Detector

[Procedure amendment]

[Submission date] May 11, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[Description of reference numerals] 10 fuel cell 50 reformer 51 burners 60 orthogonal transform apparatus 71 load detector 72 switcher 74 second operator 80 limiter 82 third computing unit 90 temperature detector

Claims (3)

[Claims] 1. A reformer for reforming a mixed gas, the flow rate of which is controlled by a raw material gas control valve and a steam control valve, and a fuel for generating power by receiving the fuel gas reformed by the reformer. A battery, a quadrature conversion device that converts the direct current output of the fuel cell into an alternating current and supplies it to a load, and a control that controls the opening of each of the control valves based on the output of the quadrature conversion device and a given set value. In the operation control device of the fuel cell power generator including means, a load detection unit that detects a sudden change in the load based on the output of the orthogonal transformation device, and according to the change amount when the load sudden change is detected by the load detection unit. An operation control device for a fuel cell power generation device, comprising: a correction control unit that gives an opening difference of each of the control valves and corrects and controls the opening. 2. A reformer for reforming a mixed gas, the flow rate of which is controlled by a raw material gas control valve and a steam control valve, and a combustion air control valve for controlling the supply of combustion air to a burner section of the reformer. A fuel cell that receives the supply of the fuel gas reformed by the reformer to generate electric power; an orthogonal converter that converts the DC output of the fuel cell into an alternating current and supplies it to a load; In the operation control device of the fuel cell power generator including the control means for controlling the opening degree of each control valve based on the output and the given set value, the sudden change of the load is detected based on the output of the orthogonal conversion device. And a correction control means for correcting and controlling the opening of the combustion air control valve in response to the change in load suddenly detected by the load detector. Fuel cell power plant operation Control device. 3. A reformer for reforming a mixed gas, the flow rate of which is controlled by a raw material gas control valve and a steam control valve, and a combustion air control valve for controlling the supply of combustion air to a burner section of the reformer. A fuel cell that receives the supply of the fuel gas reformed by the reformer to generate electric power; an orthogonal converter that converts the DC output of the fuel cell into an alternating current and supplies it to a load; In the operation control device of the fuel cell power generator including the control means for controlling the opening degree of each of the control valves based on the output and the set value given, a temperature detector for detecting the temperature of the reformer, A load detection unit that detects a sudden change in the load based on the output of the orthogonal transformation device, and the combustion air control valve is opened based on the improved raw material flow rate, the battery current, and the reformer temperature when the load detection unit detects a sudden change in the load. Correction control to correct the degree An operation control device for a fuel cell power generator, comprising: a step.