JPS58133784A - Control system of fuel cell power generating plant - Google Patents

Abstract

PURPOSE:To keep the ratio of raw fuel to steam in an optimum value by measuring the composition of raw fuel, and adjusting steam flow rate supplying to a fuel reformer according to a measured result. CONSTITUTION:An operating signal 533 of a steam flow rate adjusting valve 201 is decided by the following procedure. A main hydrogen gas system moisture setting value 527 is obtained as a function of a load command LD from the middle supply with a main hydrogen gas system moisture setting valve generator 426. The deviation from a moisture signal 528 measured with a main hydrogen gas system moisture detector 304 is obtained (a subtracter 427), and the feedback operation such as proportion, integration is conducted (a feedback controller 428) to obtain a feedback control signal 530. In a feedforward controller 429, a feedforward control signal 531 of a valve 201 is obtained as a function of a load command LD from the middle supply. An operating signal 533 of the valve 201 is decided with the feedforward control signal 531 and the feedback control signal 530.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to control of a fuel cell power generation system, and particularly to a control system for a fuel cell that requires rapid load following.

Conventional fuel control systems include a fuel cell, a hydrogen generator (called a reformer or reformer),
The fuel cell generation system consisting of the air supply system was configured to be operated independently by nine control devices.

That is, the fuel cell power generation system, as shown schematically in Figure 1, consists of raw fuel (LNG) and naphtha that are supplied as raw fuel, J4 node valve 00, and raw fuel (naphtha). ) FJ @ section valve 7 allows raw fuel (
The steam 102i supplied by the combined fuel) 101 and the steam flow regulating valve 201 is mixed with the large volume gas 115 and naphtha 1161, and the hydrogen gas 107t at the outlet of the Ochi 205 is heated as fuel, and the hydrogen gas is heated as a fuel. gas 10
3, a reformer 202 that produces hydrogen lick gas lO3
The carbon monoxide *coi contained in the water vapor reacts with the water vapor to generate carbon dioxide gas COs and water 171 Hs, and the main hydrogen gas 104
- A shift comparator 203 to obtain battery hydrogen sludge control valve 204 to adjust the flow rate of hydrogen gas 105 in the pond, and a reformer exhaust gas 10 to supply oxygen used in the battery.
8 as a power source and an air supply system 20 that pressurizes air 110.
6. From the pressurized air 11'l produced by the air supply system 206 to the air 112't required by the battery, the oil separation air value adjustment valve 207, the battery 205, and the moisture in the gas are collected. This system is composed of moisture recovery heat exchangers 211, 213, and 215, and obtains the battery output current 106 through the reaction between hydrogen and d-wire. Further, the battery outlet hydrogen gas 107 is used as a heat source in the reforming table 11202 and as a power source for the air supply system 206, and then is discharged into the air as exhaust gas 109. In addition, an auxiliary fuel control valve 208 and an auxiliary air release control valve 220 adjust the auxiliary fuel 114 and auxiliary air 118 used for starting the reformer 202.
%-Hydrogen recirculation fan 209 recirculating pond outlet hydrogen gas and 4 pond outlet air Hydrogen refilling regulating valve 210 and air recirculation 4777218, air P+muts control valve 21
8 way valve.

Incidentally, a problem with such a fuel cell power generation system is the calibration of the ratio of raw fuel and water vapor supplied to the fuel reformer. In other words, the raw fuel supplied to the reformer is LNG.

These raw materials and fuels, such as naphtha, vary in composition depending on the place of production or manufacturing process.

Ninth, conventionally, the ratio of steam to raw fuel was set to be large enough to accommodate all raw fuels; however, with this method, the ratio of steam to raw fuel For raw fuels with a smaller than the above-mentioned set value, there is a problem in that extra thermal energy is consumed to raise the temperature of unnecessary water vapor, resulting in a decrease in efficiency.

The purpose of the present invention is to maintain the ratio of raw fuel and steam supplied to a fuel reformer at an appropriate value even if the composition of raw fuel varies depending on the production area or manufacturing process, and to raise the temperature of unnecessary steam. A fuel source that can improve the efficiency of fuel cell power plants by reducing thermal energy consumption
The plan is to provide itIlIogly stem.

The present invention maintains the ratio of raw fuel and steam supplied to the fuel reformer at the highest value, and increases the temperature of unnecessary steam in order to reduce energy consumption and improve efficiency. It is characterized by measuring the composition of the raw fuel and adjusting the amount of steam supplied to the fuel reformer according to the measurement results.

A fuel cell power generation plant control system according to the present invention,
It can be broadly divided into the following four categories.

(11 Fuel cell control system (see Figure 2 2#@) (2) Reformer electrical control system (see Figure 3) (3) Air supply system control system (see Figures 5 and 6) (4 ) Control system of recirculation system (see FIG. 7) The control method will be explained below in detail using one example of the four control systems.

FIG. 2 shows one embodiment of the fuel foaming control system. First, the output of the hydrogen pressure control set value generator 400 at the outlet of the reservoir as a function of the load command LD from the intermediate feeder is shown in FIG. Obtain the pond outlet hydrogen intensity setting 11i500, calculate the electrodeposition 502 with the hydrogen concentration signal 501 at the Ku-ike outlet measured by the battery outlet/kJ chastity integral detection 01 (subtractor 401), and calculate the proportional, integral, etc. After performing the feed pack control calculation, the feed back controller 402) obtains the feed pack control signal 502. on the other hand.

The feedforward control signal 504 of the valve 204 is determined as a function of the feedforward 1ttll (in the IIl unit 403, the load command LD+2 from the intermediate supply). Basically, the operation signal 506 to the valve 204 is determined by adding the feed-forward control signal 504 and the feedback control signal 503.
The operation signal to the valve 204 is corrected using the prepressure, that is, the main hydrogen gas pressure deviation signal 522 (see FIG. 3).

An example will be explained in which the battery output increases due to the addition of such supplementary iE. That is, as the battery output increases, the amount of water consumed within the battery increases. For this reason, the hydrogen-ji 501 at the outlet of the pond decreases, and to compensate for this, the feedback telJ rm unit 402
operates and opens the valve 204, thereby restoring the hydrogen concentration 501 at the foaming outlet. However, when the valve 204t is opened, the main hydrogen gas pressure 521 decreases, but in general, the response of the fuel reformer 202 (No. 11A) is slow, and the recovery of the main hydrogen gas pressure 521 is slow. If the valve 204 is controlled only by the hydrogen concentration 501 at the outlet, a problem arises in that the main hydrogen gas pressure 521 continues to decrease. This is where the effect of correcting with the main hydrogen gas pressure 1° difference signal 522 lies.

That is, in the above example, the main hydrogen gas pressure difference 522 increases in the positive direction, and via the adder 404, the valve 204tl-
In other words, wait for the function of suppressing the valve 204 from opening unilaterally, and then increase the main hydrogen gas pressure 521.
From the above point, the zero function block 405, which has the effect of suppressing fluctuations in the value, may be used in a simple proportional manner, or may move only when a certain threshold value is exceeded and hold the signal from the valve 204. In short, it is sufficient if the function of suppressing fluctuations in the main hydrogen gas pressure 521 is added to the valve 2040 control system.

In exactly the same way, the magneto-electric air control valve 207 in FIG.
The deviation from the oxygen intensity signal 508 measured by the battery outlet oxygen concentration detector 302 is calculated (subtractor 407), and a feedback controller 408) is used to perform feedback control calculations such as proportional and integral operations. Back control signal 510
get. On the other hand, the feed forward controller 409 calculates the feed forward control signal 5111 of the valve 207 as a function of the load command LD from the intermediate supply.
In addition to this feed forward control signal 511, the operation signal 513 is determined by a feedback control signal 510 and an air it*section valve passage valve C main air pressure>tS difference signal 562. The function and seedlings of block 411 are completely similar to block 405.

Next, one embodiment of the reformer control system will be explained using FIG. 3. In FIG. The main hydrogen gas system pressure setting value is 520t as a function of the load command LD from
- The obtained 0th order, the main hydrogen gas pressure detection value 521 (
Calculate the difference 522 (block 421), and perform feed pack example calculations such as proportionality and integral (block 422).
, determines the feedback control signal 523. on the other hand,
The feed forward controller 423 calculates a feed forward control signal 524f of the raw fuel demand as a function of the load demand LD from the intermediate supply.

The father, block 425, is the 4-pond outlet hydrogen tank shown in Figure 2.
This is a function for inputting the agricultural honey 1 difference signal 502 and operating the valves 200 and 217t in cooperation with the operation of the valve 204.
Calculate the signal 525 of valve 200, 217 corresponding to valve 204. The raw fuel demand signal 526 is obtained as the sum of these three signals 523, 524°525.

Next, the raw fuel t is operated using the valve 200 and the valve 217 according to the Tomohara fuel demand signal 526 obtained above, which will be explained. First, the main hydrogen gas system hydrogen concentration setting value generator 432 obtains the main hydrogen gas system water line collapse degree setting value 534 as a function of the load command LD from the intermediate supply, and the main hydrogen gas system hydrogen performance level detector 305 measures it. The deviation from the obtained hydrogen signal 535 is determined (subtractor 433), and feedback control calculations such as proportional and integral operations are performed (feedback+tilJm unit 434) to determine a feedback control signal 537. On the other hand, the feed forward controller 435 obtains a feed forward control signal 538 of the raw fuel share of the valve 200 as a function of the load command LD from the intermediate feed. The original ma ratio 539 of the valve 200 is:
In addition to this feed pot forward control signal 538, it is determined by a feed back control signal 537. valve 20
The operation signal 540 of 0 is applied to the raw fuel demand 526 by the valve 20.
It is obtained by multiplying the raw fuel share ratio 539 of 0 (multiplier 4
37). Further, the operation signal 543 of the valve 217 is changed from the signal 541 corresponding to the constant 1 to the raw fuel share ratio 539 of the valve 200.
It is obtained by subtracting t (subtractor 438) and multiplying the obtained raw fuel share 542 of the valve 217 by the raw fuel demand 526t (multiplier 439).

9. Operation of the water vapor flow regulating valve 201 No. 6 533 is as follows:
Determine as follows. First, the main hydrogen gas system moisture set value generator 426 obtains the main hydrogen gas system moisture set value 527 as a function of the load command Ll) from the intermediate supply, and the main hydrogen gas system moisture detector 304 measures the moisture content >1. Find the one gate difference with No. 528 (subtractor 427), and use the proportional/integral feed/pack controller'&! By applying L, the feedback controller 428) obtains the feedback It+lj@ signal 530. On the other hand, feed forward I controller 4
In step 29, the feed forward control signal 531 of the valve 201 is obtained as the number of negative@commands LDtDIa from the intermediate feed. Valve 2010 operation (t4 533 is determined by this feed forward + blJ m iWi 531) feed back control signal 530.

In addition, the auxiliary fuel control valve 208 and the auxiliary air amount control valve 2
The operation signals 557 and 558 of No. 20 are determined as shown in Fig. 4. First, a temperature setting value of 550 t is obtained as a function of the load command LD from the intermediate supply by the re-former outlet hydrogen-rich gas system temperature setting 1 direct generator 450, and the temperature is measured by the re-former exit hydrogen-rich gas system temperature detection 4308. A deviation from the temperature signal 551 is determined (subtractor 451), and feedback control calculations such as proportional and integral operations are performed using a feedback controller 453) to obtain a feedback control signal 553t. On the other hand, the feed-forward controller 454 controls the valve 2 as a function of the load command LD from the intermediate supply.
08 feed forward control signal 555 is determined.

In addition, the over/amp firing controller 452 generates a control signal 55 for over/amp firing the auxiliary fuel in accordance with the time change of the load command LD from the intermediate supply.
Find 4. The operating signal 557 for the valve 208 is determined by the feed forward control signal 555, the feedback control signal 553 and the over/a/da firing control signal 554 described above.

The operating signal 55B for the valve 22G is determined by the ratio setting device 457 based on the operating signal 557 for the valve 208 so that the ratio between the auxiliary fuel 114 and the auxiliary air 118 is maintained at a constant ratio.

FIG. 5 shows the equipment configuration of the air supply system 206.

In the figure, the power source is the exhaust gas 108 of the fuel reformer 202,
This exhaust gas drives a gas turbine 2062, and a compressor 2063 directly connected to the gas turbine 2062 increases the pressure of the air 110 to the pressure required by the fuel cell, and supplies the air 110 to the fuel cell.

The fc empty fil 11 is pressed 1'd and the valve 207 (8
1), the amount of air required by the fuel cell is extracted, and the remaining air is sent to the gas turbine 2062 via the valve 2061t.
is discharged as exhaust gas 109.

Although not shown in the figure, a portion of the compressed air 111 is also used as air for hydrogen combustion in the reformer 202.

FIG. 6 shows a control method for the air supply system 206.

First, in the main air system pressure setting value generator 460, a setting value 560 of the front pressure (main air system pressure) 561 of the valve 207 is determined as a function of the load command LD from the intermediate supply, and the main air system pressure detection 6
The output 561 and part 562 of 309 are obtained. Next, block-1-462) executes feedback control calculations such as proportional and integral operations, and the feedback control signal 563
Determine. On the other hand, feed forward controller 463
Then, as a function of the load command LD from the intermediate supply, the valve 2061
Determine the feed forward signal 564 of . Block 465 also determines the signal 565 of valve 215 corresponding to valve 207 since it is in coordination with valve 207 .

Next, one embodiment of the control system of the recirculation system will be explained using FIG. 7. In FIG. The outlet hydrogen gas system pressure setting value 570 is determined. Next, the deviation 572 from the battery outlet hydrogen gas system pressure signal 571 is calculated (C block 471), and feedback control calculations such as proportional and integral are executed (block 472), and the feedback control signal 573't- is determined. . On the other hand, the feed
The forward controller 473 receives the load command LD from the intermediate supply.
Determine the feed forward signal 574 of the hydrogen recirculation regulating valve 210 as a function of . Block 475 cooperates with the operation of oxygen recirculation amount control valve 219 to control valve 210.
This is the ninth function that operates the signal 575t of the valve 210 in response to the signal of the valve 219. The operation signal 576 of the valve 210 is composed of these three signals 573, 574, 5
It is found as the sum of 75.

In addition, the operation signal 59 of the oxygen recirculation amount control valve 219 in the same figure
1Fi is determined as follows. First, the battery outlet hydrogen gas system/air system moisture ratio set value generator 483 obtains the hydrogen gas system/air system moisture ratio set value 580 as a function of the load command LD from the intermediate supply, and the foaming outlet hydrogen gas system moisture Detector 3
06 and the ratio 579 of the filtrate moisture signal 577.578 measured by the battery outlet air system moisture detector 307 is determined (
A resuscitator 411), a feed pack controller 485) for performing feedback control calculations such as proportional and integral, and a feed pack control signal 582 are obtained. On the other hand, the differential pressure setting value generator 476 for the leakage hydrogen gas system and the air system calculates the differential pressure setting value 583 as a function of the load command LD from the intermediate supply. The battery outlet air system pressure setting 1 straight 585 is determined by the feedback control signal 582 and the battery outlet hydrogen gas system pressure signal 571 in addition to this differential pressure setting value 583, and is measured by the battery outlet air system pressure detection 312. Air pressure signal 5
86 (subtractor 478), performs feedback control calculations such as proportional and integral operations (feedback control 6479), and obtains a feed pack control signal 588. Further, the feed forward controller 480 obtains a feed self-forward control signal 589 for the valve 219 as a function of the load command LD from the intermediate supply. The operation signal 591 of the valve 219 is based on this feed rumor forward control signal 58
9, a feedback control signal 588, and a battery outlet hydrogen gas system pressure deviation 572.

In one embodiment of the invention, the amount of steam 102 supplied to the reformer 202 is controlled by a moisture feed pack in the main hydrogen gas system (see FIG. 3), as shown in FIG. The main hydrogen gas system may be controlled by carbon monoxide (CO) @ degree feedback, that is, first, the hydrogen gas system - carbon oxide concentration set value generator 6
00, the main hydrogen gas system - carbon oxide set value 70G is obtained as a function of the 94 load command LD from the intermediate supply, and the main hydrogen gas system -
The deviation from the carbon monoxide concentration signal 701 measured by the carbon oxide concentration detector 311 is calculated (subtractor 601), and the feedback control calculations such as proportional and integral are calculated.
pack controller 602), feed pack control signal 70
Get 3. On the other hand, the feed forward controller 603 obtains a feed forward control signal 704 for the valve 201 as a function of the load command LD from the intermediate supply. valve 201
The operation signal 705 is determined by the feed forward control signal 704 and the feedback control signal 703.

In one embodiment of the invention, the set value of the control variable and the feed forward control signal are determined as a function of the load command LD from the intermediate supply, but if the signal is equivalent to the load command LD from the intermediate supply, For example, it may be the battery outlet current, or it may be the load demand set by the operator.

In one embodiment of the invention, the battery outlet air system pressure set value is determined by the battery outlet hydrogen gas system pressure signal and the battery hydrogen gas system pressure signal.
Although it is determined based on the air system differential pressure setting value, it may also be determined based on the battery outlet hydrogen gas system pressure setting value and the battery hydrogen gas system/air system differential pressure setting value. Determine the battery outlet air system pressure set value as a function of the load command LD, and set the battery outlet hydrogen gas system pressure set value to the battery hydrogen gas system/air system differential pressure set value and the battery outlet air system pressure signal or battery outlet air. It may be determined based on the system pressure setting value.

In one embodiment of the invention, the hydrogen concentration at the battery outlet and the oxygen concentration at the battery outlet are controlled by the battery hydrogen gas flow rate and the battery air flow rate, respectively, and the hydrogen gas system pressure at the battery outlet and the battery outlet air system pressure are controlled by hydrogen recirculation. However, the hydrogen gas system pressure at the battery outlet and the air system pressure at the battery outlet were controlled by the battery hydrogen gas flow rate and battery air flow rate, respectively. The outlet oxygen concentration may be controlled by the amount of hydrogen recirculation and the amount of air recirculation, respectively.

In one embodiment of the invention, the amount of water vapor 102 supplied to the reformer 202 is determined according to the moisture content of the main hydrogen gas system, but the composition of the raw fuel is measured and the amount of water vapor 102 supplied to the reformer 202 is Alternatively, the amount of water vapor 102 to be supplied may be determined.

In one embodiment of the invention, predetermined operating conditions (temperature, pressure) for the reformer and fuel cell are used, and a friend measures the composition of the raw fuel and reforms it according to the results. The operating conditions for the device and the fuel cell may be determined, and the reformer and the fuel cell may be operated under these conditions.

In one embodiment of the invention, a fuel cell temperature control system is not illustrated, but this control system performs feed/forward control of the fuel cell cooling water flow rate in accordance with a load command from an intermediate supply, and 1! The deviation from the fuel cell temperature set value tm degree measured value determined as a function of the lFt command is subjected to feedback control processing, and the fuel cell cooling water flow rate is corrected and controlled using the mourning signal.

The present invention measures the composition of raw fuel and adjusts the flow rate of steam supplied to the fuel reformer according to the measurement result.
Even if the raw fuel composition varies depending on the production area or manufacturing process, the ratio of raw fuel and steam supplied to the fuel reformer can be maintained at an optimal value, reducing the consumption of thermal energy to raise the temperature of unnecessary steam. This has the effect of improving the efficiency of fuel cell power generation plants.

[Brief explanation of the drawing]

Fig. 1 shows a schematic configuration of a fuel cell power generation plant that is the object of control of the present invention, and Fig. 2 shows an example of a fuel cell control system.
Figure 3.4 shows one embodiment of the fuel reformer control system, Figure 5 shows the equipment configuration of the air supply system, and Figure 6 shows one example of the control system of the air supply system.
Embodiment FIG. 7 shows one embodiment of a control system for a recirculation system, and FIG. 8 shows another embodiment of a fuel reformer control system. 101...Raw fuel, 102...Steam, 103...
・Hydrogen rich gas, 104... Main hydrogen gas, 105・
...Battery inlet hydrogen gas, 106...Battery outlet current, 1
07... Battery outlet hydrogen gas, 108... Reformer exhaust gas, 109... Exhaust gas, 110... Air, 111
... Pressurized air, 112 ... Battery inlet air, 113.
...Battery outlet current, 114...Auxiliary fuel, 115...
・Raw fuel (LNG), 116...Raw fuel (naphtha),
117... Water vapor, 118... Auxiliary air, 200...
・・Raw fuel (LNG) control valve, 201 ・・Steam n,
Control valve, 202... reformer fill (reformer)
, 203...Shift converter, 204...Battery hydrogen gas control valve, 205...Battery, 206...Air supply system, 207...Battery air! Control valve, 208...
Auxiliary fuel control valve, 209...Hydrogen recirculation fan, 21
0...Hydrogen recirculation amount control valve, 211...Moisture recovery heat exchanger, 212...Drainage amount control valve, 213...Moisture recovery heat exchanger, 214...Drainage IL-control valve, 215
...Moisture recovery heat exchanger, 216...Drainage volume adjustment measure
4 (21 308

Claims (1)

[Claims] 1. Fuel reforming kmMm for reforming raw fuel as a mixed component into hydrogen gas, an air supply system for supplying compressed FC oxygen gas, and a reaction between the supplied hydrogen gas and oxygen gas. I
In the Hatashina Battery@Koshi plant, which is composed of fuel cells that output t flow, the steam flow 11 to be supplied to the fuel reformer according to the composition of the raw fuel is: I4. -Plant control system. 2. In the fuel pond-originated sybrant all # system according to claim 1, the flow rate of water vapor supplied to the fuel reformer is feed-forward controlled as a function of load) 1, and the composition of the raw fuel is controlled. A fuel pond power generation plant control system characterized by correcting the water vapor flow f supplied to the material reforming device according to +titl@t-.