JP2810367B2 - Operating method of fuel cell power plant and fuel cell power plant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cogeneration plug using a fuel cell.
In particular, stable operation up to low load range
Can be selected and the heat / electronic output can be selected arbitrarily.
Operating method and its device.
You. [Prior art] In a conventional fuel cell power plant, Japanese Patent Publication No. 58-56231
Unreacted fuel in the fuel cell anode as described in
By supplying heat to the reformer combustion section,
The aim was to improve the power generation efficiency at the rated power. But partial negative
Driving method during loading, especially for cogeneration
No consideration was given to the characteristics under minute load
Therefore, no special consideration was given. [Problems to be Solved by the Invention] In the above prior art, the operation method under a partial load is not described.
Power generation efficiency during rated load operation
Therefore, a pressurized power plant is configured. And
During partial load operation, the auxiliary turbine is
Keep the compressor at nearly constant operating conditions over the entire load range,
The operating pressure of the runt is kept constant. Thus the pressure
If the pressure is kept constant, the control characteristics of the fuel control valve and the expansion
Since the operating characteristics of the bin compressor are restricted,
Poor operating characteristics, especially high minimum load factor
There is. Also, in cogeneration plants
Has a load operation that addresses both power and heat demand.
There was a problem that it was not possible. An object of the present invention is to provide a partial load of a pressurized fuel cell plant.
At the same time as co-generation
Electrical power and heat output at an arbitrary ratio
Excellent load operability that can supply power and reliability
A highly efficient and efficient fuel cell power plant operation method
Another purpose is to implement the above method properly.
It is to provide a fuel cell power plant that can be used. [Means for Solving the Problems] In the operation method of the fuel cell power plant according to the present invention,
Calculates the fuel pressure of the fuel system based on the power demand load signal.
Select and absorb the difference between the selected pressure and the current fuel pressure
Adjusting the opening of the fuel pressure adjustment valve to
Heat exchange of cathode exhaust gas discharged from the pond cathode,
Adjusting the heat input of exhaust gas supplied to the expansion turbine
The exhaust gas supplied from the expansion turbine to the exhaust heat recovery boiler
Adjusting the heat input of the gas.
Things. In the fuel cell power plant of the present invention,
Select the fuel pressure of the fuel system based on the required load signal,
In order to absorb the difference between the selected pressure and the current fuel pressure, the fuel
Means for adjusting the opening of the fuel pressure regulating valve and cathode exhaust gas
It is installed in the middle of the system and exchanges heat with the cathode exhaust gas.
And heat exchanged cathode exhaust gas into an expansion turbine.
Heat recovery boiler to be supplied to the
Installed in the exhaust system of exhaust gas
Of waste gas supplied to the waste heat recovery boiler
Characterized by having an auxiliary combustion device for adjusting the amount of heat input
Is what you do. [Operation] In the operation method of the fuel cell power plant according to the present invention,
The fuel pressure of the fuel system based on the power demand load signal.
Force and select the difference between the selected pressure and the current fuel pressure.
There is a process to adjust the opening of the fuel pressure control valve to absorb
Therefore, the electric output can be controlled and the fuel cell
The cathode exhaust gas discharged from the cathode exchanges heat and expands.
Adjusting the heat input of the exhaust gas supplied to the tension turbine
The exhaust gas supplied from the expansion turbine to the exhaust heat recovery boiler
It has a process to adjust the heat input of the gas, so the heat output is controlled.
And therefore the electrical and thermal output
It can be supplied at any ratio, and the power demand and heat demand
Can handle both demands of
High reliability and high efficiency can be obtained. Further, in the fuel cell power plant of the present invention,
The fuel pressure of the fuel system based on the power demand load signal.
Select and absorb the difference between the selected pressure and the current fuel pressure
Means for adjusting the opening of the fuel pressure regulating valve to
Installed in the middle of the exhaust gas system,
Heat exchange and expansion of heat exchanged cathode exhaust gas
Heat recovery boiler to supply to turbine and expansion turbine
In the exhaust system of exhaust gas discharged from
Of waste gas supplied to the waste heat recovery boiler
And an auxiliary combustion device for adjusting the heat input.
Thus, the above method can be performed accurately. Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 15.
I do. 1 to 8 show a fuel cell power generation unit according to the present invention.
The first fruit of the plant to implement the method of operating the runt
An example is shown. Fuel cell power generation plug for implementing the operation method of the present invention
The fuel 1 shown in Fig. 1 is approximately 6 to 10 kg / cm ^Two Pressurized
And supplied to the reformer 4. In the reformer 4, natural gas
Of the expansion turbine 37 in the reformer reactor 5
A reforming reaction occurs with steam 3 generated by the recovery boiler 41 and the like.
The main component is fuel (hydrogen) and carbon monoxide
Reform into gas. Reaction gas mainly composed of reformed hydrogen and carbon monoxide
The fuel is supplied to the anode 9 of the fuel cell 8 at about 600 ° C. The fuel cell 8 used in the present embodiment is a fuel cell laminated body.
Each fuel cell has a positive electrode, a negative electrode, and both
An electrolyte 10 placed between the electrodes and a non-electrolyte side of the positive electrode
Gas passage (the cathode and the cathode gas passage are connected to the cathode 11
) And a gas passage (negative electrode) provided on the non-electrolyte side of the negative electrode.
(Anode and anode gas passages are referred to as anodes 9). In this embodiment, the electrolyte 10 contains lithium carbonate and potassium carbonate.
About 550 ° C, when it uses a carbonate such as
Use a molten carbonate type operating at a temperature of ~ 700 ° C
Have been. The reaction gas 7 supplied to the anode 9 is supplied to the cathode 11
Gas mixture with supplied air and carbon dioxide (oxidant gas
React with 30). At the cathode 11, the oxidizing gas is
Upon receiving the electrons, they become carbonate ions and enter the electrolyte 10.
You. At the anode 9, hydrogen and carbonate ions in the electrolyte react with each other.
In response, it generates carbon dioxide gas and water and emits electrons. this
As a result, electrons move from the anode 9 to the cathode 11
Generates a current. The anode exhaust gas 12 of the fuel cell 8 includes
Formed by the reaction of hydrogen and carbon monoxide with carbonate ions
Contains carbon dioxide and water. And this anode
The exhaust gas 12 is cooled by heat exchange in a gas / gas heat exchanger 13.
It is. This is further cooled by the gas cooler 87,
The water is separated by the separator 15. Anode separated from water
The exhaust gas 17 is compressed by the compressor 18 and goes to the reformer combustion section 6.
Supplied. React fuel 1 with steam 3 to convert to hydrogen and carbon monoxide
Steam reforming reaction is an endothermic reaction,
Need to be In this embodiment, the fuel is supplied to the reformer combustion section 6.
Supply battery anode exhaust gas 12 (20), contained in gas
Of unreacted fuel such as hydrogen and carbon monoxide
Has been supplied. The reaction of the reformer 4 depends on the fuel 1 supplied to the reformer reactor 5.
So that the ratio of steam to steam 3 is constant.
Controlling the flow rate of the gas 3 and keeping the reaction temperature constant
The combustion temperature 84 of the reformer combustion section 6 is supplied to the air flow control valve 73.
More by adjusting the excess air ratio.
You. Oxidant gas (mixed gas) supplied to the cathode 11 of the fuel cell 8
30) is a gas mixture of air and carbon dioxide as described above.
Is. Of which, the air is rated negative by the air compressor 36.
6 ~ 10kg / cm when loading ^Two And is supplied to it. Meanwhile, charcoal
The acid gas is supplied as an exhaust gas 21 of the reformer combustion section 6.
You. Exhaust gas 21 is used as anode exhaust gas 20 as fuel.
Pressurizing with compressor 18 and pressurizing air 27 with compressor 36
6 to 10 kg / cm during rated load operation ^Two Generated to
I have. The fuel cell 8 has a reaction pressure, a reaction temperature, a fuel in the reaction gas.
The higher the charge concentration, the more the heat output of the reaction gas
Is known to have high power generation efficiency
I have. Regarding the reaction gas pressure, the power generation efficiency of the fuel cell is
The higher the power, the higher it will be.
About 10kg / cm ^Two In general, Of the calorific value of the gas reacted by the fuel cell, the electric output
The amount of heat that cannot be extracted as
Cooling the fuel cell to convert it to heat
Need to be The cooling of the fuel cell 8 is applied to the anode 9 and the cathode 11.
Cooling by flowing a large amount of gas. Fuel cell cathode 11
Exhaust gas 32 is supplied to an expansion turbine 37 and the expansion turbine
The heat recovery is performed by driving the compressor 36 with the
ing. The fuel cell power plant comprises a reformer 4, a fuel cell 8, an expansion
Bins 37 balance each other to form a heat recovery system
The total power generation efficiency of the plant during rated load operation.
It achieves a rate of 45-50% and a total thermal efficiency of 80-85%. The fuel cell 8 is composed of a thin fuel cell stack.
Therefore, the differential pressure between the anode 9 and the cathode 11 is 0.01 to 0.
1kg / cm ^Two It is necessary to hold down to the extent. In a conventional pressurized fuel cell plant, the fuel pressure is kept constant.
The fuel flow rate is controlled by the fuel flow rate regulating valve 68 to expand
Supplementary fuel is supplied to the turbine 37, and the expansion turbine 37 is
The operation was almost constant and the partial load was operated. this
In this case, the adjustment range of the fuel flow control valve 68 is about 20 to 100%.
And the operating characteristics of the expansion turbine 37
Partial load operation of the body is restricted. The adjustment of the fuel flow control valve 68 is performed as shown in FIG.
The difference calculation unit 66a of the control device 66
Comparing the load request signal 64 with the load set value and finding the difference
At the same time, when the fuel flow rate is determined according to the determined difference,
In 66b, based on the value, selector 66c, automatic / manual switching
Signal for valve via changer (automatic in this case) 66d
The output to the converter 66e is converted to fuel
The opening of the flow control valve 68 is adjusted. According to the present invention, the power load request to the fuel cell power plant is
A fuel pressure is selected based on the signal 64, and the selected fuel pressure is selected.
By adjusting the opening of the pressure regulating valve 65 according to the force,
The electric output of the fuel cell 8 is controlled. That is, as shown in FIG.
Install the fuel pressure transmitter (PX) 102 in the middle
As shown in FIG.
Is input, the difference calculation unit 66a outputs the power load request signal 6
4 and the fuel pressure detected by pressure transmitter 102
Power based on a predetermined relationship between load and pressure.
While selecting the fuel pressure corresponding to the load request signal 64,
The selected fuel pressure and the current load signal 62 of the fuel cell 8 are
The difference from the corresponding fuel pressure is determined, and the proportional gain 66
b is a selector 66c for auto / manual
Switch 66d (automatic in this case)
The converter 66e outputs the electric signal for the valve.
To adjust the opening of the fuel pressure regulating valve 65.
Adjust. Therefore, it is selected based on the power load request signal 64.
To absorb the difference between the measured fuel pressure and the current fuel pressure.
By adjusting the opening of the fuel pressure adjustment valve 65,
Output 48 is controlled. In addition, the expansion turbine 37 corresponds to the selected fuel pressure.
By adjusting the calorific value of the exhaust gas supplied to the compressor
The discharge air pressure of the fuel cell 8 is controlled so that the anode 9
The differential pressure between the swords 11 is kept within the allowable value range. That is, between the cathode 11 of the fuel cell 8 and the expansion turbine 37
A heat recovery boiler 81 is installed at an intermediate position in the exhaust gas line of
Exhaust gas from sword 11 passes through heat recovery boiler 81
Control the amount of heat of the exhaust gas supplied to the expansion turbine 37
Is in place. In this case, the power supplied to the heat recovery boiler 81
By adjusting the flow rate of the water 82, the calorific value of the exhaust gas is controlled. As shown in FIG. 1, the flow rate of the feed water 82 is adjusted by the compressor 36.
Transmitter 80 that detects the pressure of air supplied from
You. Then, the controller 66 calculates the difference as shown in FIG.
The section 66a receives the detection signal (pneumatic pressure) from the detector 80 and
Comparison with the detection signal (fuel pressure) from the fuel pressure transmitter 102
And determine the difference, and the water supply 82 corresponding to the difference
The flow rate is calculated, and the proportional gain 66b is calculated based on the calculated value.
Output to converter 66e via selector 66c and switch 66d
Thus, the opening of the water supply flow rate adjustment valve 83 is adjusted. this
Adjustment controls the amount of steam sent to heat recovery boiler 81
Is controlled, so that the gas to be supplied to the expansion turbine 37 is controlled.
The heat input amount of the mode exhaust gas 32 is controlled. The electrical output 48 generated by the fuel cell travels through the electrolyte 10
Is proportional to the number of ions. That is, the weight of the supplied fuel
It will be proportional to the mass flow rate. The weight flow rate of the fuel
Since it is proportional to the pressure, adjust the fuel pressure
The supplied fuel gas (mixed gas of reaction gas 7 and exhaust gas)
If adjusted, the electric output of the fuel cell 8 is controlled as a result.
be able to. Furthermore, in accordance with the flow rate and pressure characteristics of the compressor 36,
It is necessary to keep the reaction temperature of the quality reaction and the battery reaction constant. The discharge air flow rate of the compressor 36 is almost proportional to the discharge pressure.
Although it decreases, the insulation efficiency of the expansion turbine 37 and compressor 36 is low.
The operating point of the expansion turbine and compressor is below the fuel cell
The operating point shifts to a relatively high load area as compared with the operating point No. 8. I
Therefore, the discharge air flow rate is set to the flow rate required for the reaction.
Supplied in excess. Reformer 4 reaction depends on temperature
Therefore, the temperature of the reformer combustion section 6 is controlled by the air flow control valve 73.
The control is performed by controlling the air-fuel ratio. That
In order to detect the temperature of the reformer combustion section 6,
A transmitter 84 is installed, and a difference calculation unit 66a is provided in the control device 66.
As shown in FIG. 5, the detected temperature of the
By comparing with the set value (SG),
In both cases, the air flow rate corresponding to the obtained difference is calculated, and the proportional
The selector 66c and the switching unit 6
Output to the converter 66e via 6d, the air flow regulating valve 73
Is adjusted. Regarding the reaction temperature of the fuel cell 8, the cathode outlet gas
Part of the temperature gas of 31 is removed by the cathode recirculation compressor 34
This is done by recirculation. During the partial load operation, the air 77 supplied to the reformer combustion section 6
A part 46 of the fuel is sent to the auxiliary combustor 69 to empty the reformer combustion section 6.
Since part of the air bypasses, it is supplied to the cathode 11.
Since the temperature of the oxidizing gas 21 decreases, the cathode circulation
Although the flow rate may increase and the auxiliary power may increase,
The auxiliary combustor 69 installed at the outlet of the reformer combustion section 6
And a part of fuel 1 is drawn in as auxiliary fuel 47,
The temperature of the oxidizing gas 21 is supplied by the
Is controlling. Therefore, as shown in FIG.
Temperature transmitter 85 for detecting
As shown in FIG. 6, the difference calculation unit 66a
Therefore, based on the detected gas temperature and the power load request signal 64,
Then, the temperature corresponding to the power load request signal is selected,
Find the difference between the selected temperature and the temperature corresponding to the load signal 62.
In addition, the fuel amount corresponding to the difference is obtained, and the proportional gain 66
Selector 66c, auto / manual switching based on the difference
Output to the converter 66e via the changer 66d.
Adjust the opening of auxiliary fuel adjustment valve 43 to control oxidant gas temperature
doing. For demand for heat output, separate from demand for electrical output,
A part of fuel 1 is supplied as auxiliary fuel 55 at the inlet side of heat recovery steam generator 41.
By installing the auxiliary combustion device 45 drawn out as
Can respond. That is, an intermediate position of the fuel 1 pipe
A pipe with an auxiliary fuel regulating valve 44 and auxiliary combustion device 45
Exhaust gas from the expansion turbine 37 to the auxiliary combustion device 45
39 and supplementary fuel 55 are supplied to further
The gas 58 is sent to the exhaust heat recovery boiler 41. Here, when the auxiliary fuel 55 is used and increased, the auxiliary fuel 55 is used.
Fuel supply shortage, the fuel
For combustion air flow, the fuel flow supplied to the plant
Calculate the required air volume from the volume, electrical output 48 and heat output
Adjust the bypass air flow control valve 74. That is, as shown in FIG.
Transmission of fuel flow between fuel compressor 49 and fuel pressure regulating valve 65
With the compressor 101 installed, the flow rate of air 27 from the compressor 36
Is installed. And the system
The control device 66 is, as shown in FIG.
While taking in their detection output, electrical output and heat output,
The difference calculation unit 66a detects them and the air flow rate transmitter 111 detects them.
The flow rate is compared with that of the air flow
To determine the air flow rate according to the difference
The proportional gain 66b is output to the converter 66e based on this.
The opening of the bypass air flow control valve 74
adjust. In this case, in response to the increase in the bypass air flow rate,
Adjustment of the auxiliary fuel adjustment valve 43 increases the auxiliary fuel 47 and oxidizes it.
The temperature of the agent gas 21 can be kept at the set value. In addition, by increasing the flow rate of auxiliary fuel 47 and 55, bypass
The required air flow 46 increases. However, the fuel cell output
Even in certain cases, the air pressure increases as the auxiliary fuel increases.
As the pressure drops, the expansion turbine
What is necessary is just to increase a load. This allows the entire plant
Pressure balances. For controlling the heat output, the configuration shown in FIG. 7 may be used.
No. For example, as shown in FIG.
For detecting the supplied steam flow rate, steam pressure and steam temperature
Steam flow transmitter 104, steam pressure transmitter 105, steam temperature generator
While the transmitter 106 is installed, it is supplied from the heat recovery boiler 81.
Steam for detecting steam flow, steam pressure, and steam temperature
Flow transmitter 108, steam pressure transmitter 109, steam temperature transmitter 110
Is installed. Then, the control device 66 operates as shown in FIG.
In addition, the comparison operation unit 66f detects the detection value of each of the transmitters 104 to 106.
And the detected values of each of the transmitters 108 to 110,
The result of the comparison is further set to the heat output set value by the difference calculation unit 66a.
Calculate the difference by comparing with, and assist to correspond to the obtained difference
The fuel supply amount is calculated, and the proportional gain is calculated based on the calculated value.
66b is output to converter 66e via selector 66c and switch 66d.
Force to adjust the opening of the auxiliary fuel adjustment valve 44.
U. According to the above embodiment, adjusting the pressure of the fuel 1
Can control the electrical output 48 and the expansion
Heat input to bin 37, heat input to waste heat recovery boiler 41, and
By adjusting the amount of air and fuel to the
The operation of the fuel cell is independent of the electrical output 48 of the pond 8.
The heat output can be arbitrarily obtained within the rotation limit range.
You. The means for changing the fuel pressure includes fuel compression.
The fuel flow rate and fuel pressure by controlling the rotation speed of the machine 49
It is also possible. Especially in fuel cell power plants
The DC electrical output 48 from the fuel cell 8
It is also possible to control the number of revolutions by a flow motor. Also, use a multi-stage reciprocating compressor to respond to the load range.
Adjust the number of stages to switch the number of stages for large load changes.
Pressure fine adjustment that cannot be adjusted by switching the number of stages.
The adjustment can be performed by the adjustment valve 65. FIG. 9 shows a second example of a plant for carrying out the method of the present invention.
In this embodiment, the fuel pressure is changed according to the rotation speed of the compressor 49.
Adjusted. That is, the control device 66, as shown in FIG.
66a selects fuel pressure based on power load request signal 64
Calculating the difference between the selected fuel pressure and the current fuel pressure.
And the electric motor 49A of the fuel compressor 49 corresponding to the difference.
The rotational speed is determined, and a proportional gain 66b is set based on the determined value.
Motor 49A for the fuel compressor 49 via the collector 66c and the switch 66d
And the motor 49A is driven at the determined rotational speed.
The number of revolutions of the fuel compressor 49 is adjusted by the above. I
Therefore, the fuel pressure is adjusted by changing the rotation speed of the fuel compressor 49.
As described above, the fuel pressure is adjusted.
This is basically the same as the first embodiment. 3 to 8 are the same as in the first embodiment.
Since it can be shared and achieve the same effect,
Then, the description is omitted. FIG. 10 and FIG. 11 also show a third embodiment.
You. In this example, FIGS. 3 to 6 described above are shared.
doing. The difference between this embodiment and the previous embodiment is that
The output is controlled mainly by adjusting the load of the heat recovery boiler 81.
It is intended to be performed. That is, in this embodiment,
Therefore, the control device 66, as shown in FIG.
Are the detected values of the transmitters 104 to 106 and the transmitters 108 to 110
With the detected values of
The difference is obtained by comparing with the heat output set value by the minute calculation unit 66a,
Calculate the auxiliary fuel supply amount so as to correspond to the obtained difference,
Based on that, the proportional gain 66b changes the selector 66c and the switch 66d.
Output to the converter 66e through the auxiliary fuel regulating valve 43
To adjust. As for the temperature control of the oxidizing gas 21,
Based on the detection signal from the temperature transmitter 85 and the load request signal.
The amount of bypass air 46 to be supplied to the reformer auxiliary combustor 69
Is roughly adjusted in the first embodiment.
6 is similar to that of FIG.
I do. Each of the above embodiments corresponds to the output signal 62 of the fuel cell 8.
And select the fuel pressure so that the selected fuel pressure is reached.
By changing the pressure of the fuel 1 by various means,
Large load changes are handled by the fuel pressure and small load changes.
Can be dealt with by the fuel flow control valve 26,
The load operation range can be reliably increased. Reason
What used to be about 20-100% load in the past,
In the embodiment, the load can be increased to about 5 to 100%.
it can. Also, the compressor discharge air pressure corresponds to the fuel supply pressure.
Reduced auxiliary fuel for air pressurization
Power generation efficiency during partial load operation.
You. As the fuel pressure decreases, for example, 50% load operation
Sometimes the battery efficiency decreases by about 3-4%, but in the conventional example,
Had supplied auxiliary fuel equivalent to about 10-15% of the fuel
However, in the embodiment, it can be reduced to almost 0, and after all, about 6 to 10% power generation
Efficiency can be improved. Further, regardless of the electric output 48 of the fuel cell 8,
Since heat output can be obtained, each of power and heat
Operation is possible in response to demand, and the utilization rate is
The depreciation period and increase the economy.
Wear. In this embodiment, the heat / electric output ratio is set to about 0.6 to
It can be arbitrarily selected within a range of about 6%. FIG. 12 shows a fourth embodiment of a plant for carrying out the method of the present invention.
Is shown. In the first embodiment described above, the pressure of the compressor discharge air 27 is increased.
Although it was directly detected and controlled by the air pressure transmitter 80,
In this embodiment, the heat input to the expansion turbine 37 is determined.
The compressor discharge pressure is estimated from
You. That is, this embodiment has an inlet to the expansion turbine 37.
Transmits the gas temperature on the outlet side and the gas temperature on the outlet side
(Indicated by TE in the figure) and the compressor 36
When these discharge air flow rates are detected by the air flow rate transmitter 111,
The control device 66 calculates the above heat input based on them.
It is. FIG. 13 shows that the auxiliary combustion device 45 is placed on the expansion turbine 37 inlet side.
14 shows a fifth embodiment installed. That is, the cathode 11
When an auxiliary combustion device 45 is installed in the middle of the exhaust gas 31
In order to guide a part 55 of the fuel 1 to the combustion device 45,
A pipe having a charge adjusting valve 44 is connected. According to this embodiment, auxiliary combustion is performed on the expansion turbine 37 inlet side.
With the installation of the device 45, expansion in response to load changes
Compare the load of the turbine 37 with the first and fourth embodiments.
And can be changed quickly. FIG. 14 shows another embodiment. In the first to third embodiments, the anode outlet gas 20 is
An example in which the fuel was supplied to the reformer combustion section 6 was shown.
In other words, the anode outlet gas 20 can be supplied to the auxiliary combustor 69.
It is the one that was plumbed. According to this embodiment, during the partial load operation, the fuel cell
Excess fuel will be supplied and the fuel cell anode
As compared with the first embodiment, the hydrogen concentration in
Power generation efficiency during partial load operation.
You. The improvement is about 3 to 4% compared to the first embodiment.
You. FIG. 15 shows a first example of the calorific power generation plant according to the present invention.
4 shows a partial load characteristic in the embodiment. Electric output at 94,
The heat output at minimum and at maximum is indicated by 96. Heat output
The heat / electricity output can be varied in the range of 95 to 96.
The power ratio can be varied from 97 to 98.
As a result, the utilization rate of
It can be seen that the cost performance is improved. [Effects of the Invention] As described above, according to the method of the present invention, the power demand
The fuel pressure of the fuel system is selected based on the load signal.
Fuel pressure to absorb the difference between the set pressure and the current fuel pressure.
Adjusting the opening of the regulating valve, and from the fuel cell cathode
Heat exchange of the discharged cathode exhaust gas to the expansion turbine
In addition to adjusting the heat input of the supplied exhaust gas, the expansion
The amount of heat input of the exhaust gas supplied from the bin to the waste heat recovery boiler
Adjustment process, so that electrical output and heat output
Power can be supplied at any ratio, power demand and heat
Load management by being able to deal with both demand and demand
Of high reliability and high efficiency
There is. And in the fuel cell power plant of the present invention,
Select fuel pressure of fuel system based on power demand load signal
And absorb the difference between the selected pressure and the current fuel pressure.
Means for adjusting the opening of the fuel pressure adjusting valve,
It is installed in the middle of the gas system and exchanges heat with the cathode exhaust gas.
And heat exchanged cathode exhaust gas
Heat recovery boiler to supply to the bin and exhaust from the expansion turbine
In the exhaust system of the emitted exhaust gas, the fuel
Partial heat input of exhaust gas supplied to the waste heat recovery boiler
And an auxiliary combustion device that adjusts the amount.
There is an effect that the above-mentioned method can be performed accurately. Also, in the present invention, based on the power demand load signal,
Select the fuel pressure of the fuel system, and
Adjust the opening of the fuel pressure adjustment valve to absorb the difference from the fuel pressure.
Control means and an intermediate part of the cathode exhaust system.
And heat exchange with the cathode exhaust gas.
Heat recovery unit that supplies the exhaust gas from the exhaust gas to the expansion turbine
Ira and cathode and heat recovery in cathode exhaust system
It is installed between boilers and guides part of the fuel in the fuel system,
Adjust the calorific value of the cathode exhaust gas passing through the heat recovery boiler
And auxiliary combustion means.
There is an effect that the law can be properly implemented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall system diagram showing a first embodiment of an operating device for implementing a method of operating a fuel cell power plant according to the present invention, and FIGS. 2 to 8 are operating devices. FIG. 9 is a control explanatory diagram showing a second embodiment of the operating device, and FIG. 10 is a control of an auxiliary fuel adjusting valve also showing a third embodiment of the present invention. FIG. 11 is an explanatory diagram for controlling a bypass air flow control valve, FIG. 12 is an overall system diagram showing a fourth embodiment, and FIG. 13 is an overall system diagram showing a fifth embodiment. FIG. 14 is an overall system diagram showing another embodiment, and FIG. 15 is a table for explaining the effects of the present invention. 1 ... fuel, 3 ... steam, 4 ... reformer, 5 ... reformer reaction section, 6 ... reformer combustion section, 7 ... reaction gas, 8 ...
Fuel cell, 9: anode of fuel cell, 11: cathode of fuel cell, 12: anode outlet gas, 20: exhaust gas of anode of fuel cell, 21: exhaust gas of combustion section of reformer, 26 ...
… Air, 31, 32… exhaust gas from fuel cell cathode, 36…
Compressor, 37 ... Expansion turbine, 43 ... Auxiliary fuel regulating valve,
44 …… Auxiliary fuel regulating valve, 45 …… Auxiliary combustion device, 48 …… Electric output, 62 …… Fuel cell load signal, 64 …… Power load request signal, 65 …… Fuel pressure regulating valve, 66 …… Control device , 68 ……
Fuel flow control valve, 69 Auxiliary combustor, 73 Air flow control valve, 74 Bypass air flow control valve, 80 Air pressure transmitter, 81 Heat recovery boiler, 83 Water supply flow control valve,
84 Reformer fuel temperature transmitter, 85 Oxidant gas temperature transmitter, 102 Fuel pressure transmitter, 104,108 Steam flow transmitter, 105,109 Steam pressure transmitter, 106,110 Steam temperature Transmitter.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Hattori 3-2-1 Sachimachi, Hitachi-shi, Ibaraki Prefecture Within Hitachi Engineering Co., Ltd. (72) Inventor Takeshi Yokosuka 4-6-1 Kanda Surugadai, Chiyoda-ku, Tokyo Stock Hitachi, Ltd. (72) Inventor Naruhisa Sugita 502, Kandachicho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. (56) References JP-A-60-10566 (JP, A) JP-A-59-75571 ( JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H01M 8/00-8/24

Claims (1)

(57) [Claims] A fuel cell in which a fuel gas and an oxidant gas undergo an electrochemical reaction to output electricity, a reformer that generates and supplies the fuel gas to the fuel cell; and supplies fuel to the reformer and adjusts a fuel flow rate. A fuel system having a valve and a fuel pressure regulating valve, an expansion turbine that takes in the cathode exhaust gas discharged from the cathode of the fuel cell, heat exchange with the exhaust gas discharged from the expansion turbine to generate desired steam, and Operation of a fuel cell power plant having an exhaust heat recovery boiler for supplying part of the fuel gas to the fuel system, and an anode exhaust gas circulation system for supplying anode exhaust gas discharged from the anode of the fuel cell to the combustion section of the reformer In the method, a fuel pressure of a fuel system is selected based on a power demand load signal, and an opening of a fuel pressure regulating valve is adjusted to absorb a difference between the selected pressure and a current fuel pressure. And heat exchange of the cathode exhaust gas discharged from the fuel cell cathode to adjust the heat input amount of the exhaust gas supplied to the expansion turbine, and also adjust the heat input amount of the exhaust gas supplied from the expansion turbine to the exhaust heat recovery boiler. And an operating method of the fuel cell power plant. 2. A fuel cell in which a fuel gas and an oxidant gas perform an electrochemical reaction to output electricity; a reformer that generates the fuel gas and supplies the fuel gas to the fuel cell; and an oxidant gas discharged from a combustion section of the reformer An auxiliary combustor for heating the fuel cell, a fuel system for supplying fuel to the reformer and having a fuel flow control valve and a fuel pressure control valve, and a cathode exhaust system discharged from a cathode of the fuel cell. Expansion turbine, a compressor driven by the expansion turbine and supplying compressed air to a combustion section of a reformer, and an exhaust system for exhaust gas from the expansion turbine, and the exhaust gas and heat of the exhaust system are connected. An exhaust heat recovery boiler that generates a desired steam by replacement and supplies a part of the steam to the fuel system, and an anode exhaust gas discharged from an anode of a fuel cell is supplied to a combustion unit of a reformer. Anode exhaust gas In a fuel cell power plant having a ring system, a fuel pressure of a fuel system is selected based on a power demand load signal, and a fuel pressure regulating valve is opened to absorb a difference between the selected pressure and a current fuel pressure. A heat recovery boiler that is installed at an intermediate position in the cathode exhaust gas system, exchanges heat with the cathode exhaust gas, and supplies the heat-exchanged cathode exhaust gas to the expansion turbine; and an exhaust gas discharged from the expansion turbine. A fuel cell power plant, comprising: an auxiliary combustion device installed at an intermediate position of the exhaust system, guiding a part of the fuel of the fuel system, and adjusting the heat input amount of the exhaust gas supplied to the exhaust heat recovery boiler. . 3. 3. A reformer according to claim 2, wherein at least based on the pressure of the fuel in the fuel system and the pressure of the air discharged from the compressor, the opening of the flow control valve of the feed water supplied to the heat recovery boiler is adjusted. Means for adjusting the opening of an air flow control valve capable of adjusting the flow rate of air supplied from the compressor to the reformer combustion section based on the temperature and the set value in the combustion section; Means for adjusting the opening of an auxiliary fuel adjusting valve capable of adjusting the flow rate of fuel supplied from the fuel system to the reformer auxiliary combustor based on the temperature of the discharged oxidizing gas and the load signal of the fuel cell; The auxiliary combustion device is configured based on the steam flow rate, steam pressure, and steam temperature exchanged by the waste heat recovery boiler and the steam flow rate, steam pressure, steam temperature, and heat output setting exchanged by the heat recovery boiler. Guided fuel flow Means for adjusting the opening of the auxiliary fuel adjusting valve capable of settling, the electrical output of the fuel cell, heat output,
A means for adjusting the opening of a bypass air flow control valve capable of adjusting the amount of air supplied from the compressor to the auxiliary reformer combustor based on the fuel flow rate in the fuel system and the air flow rate from the compressor. A fuel cell power plant comprising: 4. A fuel cell in which a fuel gas and an oxidant gas perform an electrochemical reaction to output electricity; a reformer that generates the fuel gas and supplies the fuel gas to the fuel cell; and an oxidant gas discharged from a combustion section of the reformer An auxiliary combustor for heating the fuel cell, a fuel system for supplying fuel to the reformer and having a fuel flow control valve and a fuel pressure control valve, and a cathode exhaust system discharged from a cathode of the fuel cell. Expansion turbine, a compressor driven by the expansion turbine and supplying compressed air to a combustion section of a reformer, and an exhaust system for exhaust gas from the expansion turbine, and the exhaust gas and heat of the exhaust system are connected. An exhaust heat recovery boiler that generates a desired steam by replacement and supplies a part of the steam to the fuel system, and an anode exhaust gas discharged from an anode of a fuel cell is supplied to a combustion unit of a reformer. Anode exhaust gas In a fuel cell power plant having a ring system, a fuel pressure of a fuel system is selected based on a power demand load signal, and a fuel pressure regulating valve is opened to absorb a difference between the selected pressure and a current fuel pressure. A heat recovery boiler installed in the middle of the cathode exhaust gas system to exchange heat with the cathode exhaust gas and to supply the heat-exchanged cathode exhaust gas to the expansion turbine; A fuel cell power plant comprising: an auxiliary combustion device installed between recovery boilers, for guiding a part of fuel in a fuel system, and adjusting the calorific value of cathode exhaust gas passing through the heat recovery boiler. 5. 5. A reformer according to claim 4, wherein at least based on the pressure of the fuel in the fuel system and the pressure of the air discharged from the compressor, the opening degree of the flow control valve of the water supply to the heat recovery boiler is adjusted. Means for adjusting the opening of an air flow control valve capable of adjusting the flow rate of air supplied from the compressor to the reformer combustion section based on the temperature and the set value in the combustion section; Means for adjusting the opening of an auxiliary fuel adjusting valve capable of adjusting the flow rate of fuel supplied from the fuel system to the reformer auxiliary combustor based on the temperature of the discharged oxidizing gas and the load signal of the fuel cell; The auxiliary combustion device is configured based on the steam flow rate, steam pressure, and steam temperature exchanged by the waste heat recovery boiler and the steam flow rate, steam pressure, steam temperature, and heat output setting exchanged by the heat recovery boiler. Guided fuel flow Means for adjusting the opening of the auxiliary fuel adjusting valve capable of settling, the electrical output of the fuel cell, heat output,
Means for adjusting the opening of a bypass air flow control valve that can adjust the amount of air supplied from the compressor to the reformer auxiliary combustor based on the fuel flow rate in the fuel system and the air flow rate from the compressor. A fuel cell power plant comprising: