JPS6056374A - Fuel flow controlling device for fuel cell - Google Patents

Abstract

PURPOSE:To improve the response performance of a device for controlling the flow rate of fuel for a fuel cell by setting a utilization rate of the fuel with a margin, producing a fuel flow rate corresponding to the utilization rate from a finction generator by using an output current as a parameter and controlling a fuel-flow-rate-controlling valve according to the output. CONSTITUTION:The output current of the fuel cell of a fuel-cell power generation system is detected with a detector 22. The required fuel flow rate function for the normal operation condition is produced with a function generator 32 to obtain a command value. The thus obtained command value is added to the signal of a differential block 33 to produce an amended command value 35. The amended command value 35 is then added to a fuel flow rate correction amount 55 obtained from both the temperature detector of an improver catalyst layer and a fuel flow rate 23. After that, the resulting value is fed to the input of a limiter block 60 for giving an upper and a lower limit (UL) and (LL) through a PID computing element 59, thereby controlling a valve 9 for controlling the amount of fuel fed to the fuel cell. As a result, controlling can be performed while always securing the lower limit of the supplied amount of the fuel and the response efficiency of fuel supply can be improved.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a method for converting raw fuel into a reformer (
2. The reformed fuel after being converted into reformed fuel is supplied to the fuel electrode chamber of the fuel cell using hydrogen obtained from the tank as fuel through the fuel flow control valve; The present invention relates to a fuel flow rate control device for a fuel cell power generation system that uses the exhaust gas as heating fuel to maintain the reaction temperature of a reformer provided as necessary.

[Technical background of the invention and its problems]

/! i'! FIG. 1 is a system configuration diagram showing an example of a fuel cell power generation system that uses a reformer and a fuel cell according to the present invention, and the fuel cell is shown as a single cell. The hydrocarbon-based raw fuel supplied from source 1 is revised)
The fuel is guided to the catalyst layer 4 in a plurality of reforming reaction tubes (only one tree is shown) 3 stored in the R reactor 2, where a reforming reaction is carried out and the fuel is reformed into hydrogen-rich reformed fuel. Ru. Modified Kai,
The carbon monoxide contained in the water is converted into hydrogen and carbon gas in a carbon oxide converter 5, and then cooled in a low-temperature medium 8 via a second cooler 6. The water flows into the water separator 7 and is separated into heat.The thus reformed fuel 1, the main fuel, and the fuel electrode of the fuel cell 10 are passed through the fuel flow pipe and control valve 9. A compressor (not shown) is guided into the chamber 11.
What is the oxygen in the air introduced into the air chamber 12? ) - reacts mechanically and generates electricity. Sho 1
1 is the common pole, and the 12th is the air pole. The reformed fuel that has passed through the fuel electrode chamber 11 of the upper fuel reservoir 10 contains residual reformed fuel that has not reacted in the electrochemical reaction, so it must be removed first.
The Baertsuji reformer 2 (1 is led and used with integrated heating fuel [7] that supplies the heat necessary for the reforming reaction.
The unreacted residual fuel is removed from the absorber 1 at the outlet of the fuel electrode chamber 11.
3 to the cooler 14, low (, 11M medium 1
7 (cooled in step 2 and removed moisture in the remaining reformed fuel by water separator 1)
After separating -C into 5 and -C, the burner 16 (1 lead) of the reformer 2 is combusted together with the air supplied through the compressor (not shown). Air may also be used.On the other hand, electricity generated in the fuel cell 10 (2) is pumped out by 3% from the fuel electrode 11 and air electrode 12 provided on both sides of the matrix 18 holding the electrolyte, and゛C is consumed.

Next, detection of control signals used in the fuel flow rate control device according to the present invention will be explained with reference to FIG.

The output current of the fuel cell 10 is detected by a current detector 22. In addition, the flow of reformed fuel supplied to the fuel cell 10 is detected by a landscape detector 23 (2).The internal temperature of the reformer 2 is detected by a plurality of temperature detectors 24.

kl-hi has a reformer and a fuel cell according to the present invention,
I have given an overview of the fuel cell power generation system, but regarding the fuel flow control of the late 5 system, there is Ll M34 of F/4 that must be solved, so I will discuss the important problems to be solved below. However, items (1) to (4) of their problems to be solved involve only fuel cells (
This problem also occurs in the fuel cell power generation system (which does not have a reformer) and is solved by the present invention. It also applies to systems.

Problems to be solved: (1) The amount of electrochemical reactants contained in the feedstock supplied to the fuel cell, and , the output of the science electrician 704', 'i'l: Between the juice, there is a
of·? Assuming that the output current is constant, FIG. Here, the rate of reactant price profit 71- is and ro) constant r (2 based on the usage of the reactant - < (ch) = fuel? ■ the amount of reactant supplied to the pond. By the way, fuel? i5: oil output power, Electrochemistry i'+r
= jet O) Reactant n: can be calculated from the following formula (-Z-0 electrochemical equivalent -kII・kE・■
・Peku 1 unit conversion constant kE 2, Yukuihi scientific constant ■ 2 electric current, (ampere) Indicate L?3. Below is the utilization rate of the reactant -F6~
)" In other words, it is necessary to ensure a lower limit of the fuel supply amount as a parameter of the output current so that the utilization rate of the amount of reactant material in the fuel supplied to the fuel cell does not exceed the L point. be.

(2) The electrical output of the fuel cell is increased or decreased depending on the demands of the electrical load. As this ≦1, the fuel cell output current is increased or decreased, but it is necessary to supply the fuel cell with a fuel containing a reactant at least electrochemically equivalent to this output current. In fact, as stated in section (1), if the utilization rate of the reactant is increased above a certain value, the fuel cell output U:pressure decreases, and therefore the /il output decreases. It is necessary to set a margin above the limit value mentioned above and to reduce the fuel supply amount at point N shown in FIG.

(3) In Figure 2, lowering the utilization rate of the reactant supplied to the fuel cell more than necessary reduces the flow rate of the reactant that passes through the fuel cell 1 and is discharged unreacted. This means increasing the fuel cell power generation system, which results in a decrease in the efficiency of the overall fuel cell power generation system, which is not a Q measure. Therefore, the second
It is necessary to ensure an upper limit of 1゛ by adjusting the parameters of the output current so that the utilization rate does not fall below point M, which has a width of margin α at point N shown in the figure.

(4) Fuel flow - Fuel γ3 through I control valve 1-: 42 in the pond
r, (Process of supplying fuel to the electrode (:) From a control point of view, there are delay elements for each O, 1, and 1. Therefore, l, , ;'
P charge 7:5. /11. ! 1-) (4-i-7) A means is needed to improve responsiveness to sudden changes in air pressure.

(5)? (1, Rikikuichi on the Qi load side, state of zero force, target, J
When the electric and air pressures of the fuel cells are zero, it is better to continue operation without stopping the 9f, 4+n, and the time it takes to stop and start the acid generator.
7-D can be reduced, and σ) can rapidly respond to power increase requests from the electrical load side. Leave this reformer in operation＼・６
The mode of operation in which the battery output is zero is hereinafter referred to as "standby operation." During this stand-by operation, it is necessary to maintain the reforming reaction of the reformer (2 enough lees must pass through the fuel cell and be supplied to the fuel control valve C2).

(6) In the reformer, it is necessary to maintain the temperature of the medium layer at the optimum catalytic reaction temperature.

(7) Until the fuel control valve starts supplying the burner fuel of the reformer, there is a delay caused mainly by the volume sequence of the fuel cell body, absorber, water separator, piping system, etc. element exists. In order to maintain the catalyst temperature of the reformer at a certain level when the electrical output of the fuel cell power generation system changes, these delay elements must be considered.

It is necessary to design a control system that

[Purpose of the invention]

The present invention has been developed to solve the above-mentioned problems, and an object of the present invention is to provide a fuel flow rate control device for a fuel cell power generation system that solves the above-mentioned problems.

[Summary of the invention 1'? ] In order to achieve the above [J objective, in the present invention, C is the fuel 1
One car and this fuel cell? A device that supplies 1qqi,
Similarly, in a fuel cell power generation system that stores hydrogen that is supplied to the fuel cell and undergoes an electrochemical reaction with the oxygen in the air, an increase in the fuel utilization rate of the free pond (1 Determine the fuel utilization rate that takes into account a predetermined margin value from the output type [the utilization rate at which lo does not fall below a predetermined value]-limit value, and calculate the fuel utilization rate corresponding to this utilization rate (k
Is the leap that occurs as a function of the fuel cell output (1F) as a parameter? , 'to 4'l raw 2,) and the output of this function generator;
It consists of a raw material flow control valve and is classified as 21.

[Embodiments of the invention]

The control method of the present invention for solving the above-mentioned problem 1
An embodiment of the device will be described with reference to Section 2-Bfs 91S. Non-invention (1 in 1 is a regret v; ゛Quantity 5 pieces''; Section day 9 is the last one: 1:0.111 end, this 11''
The control signals necessary for the 11th motor are inputted from the left side of FIG. 1fii. In FIGS. 5 to 8, among the components of the 6i control device, the final 1: l fjl, l, . . .
The overlapping spots other than the flow rate control valve 9, which is M+, are indicated by broken lines, and one point ti! Enclose with i line and do not overlap j
': ii minutes and 1. ,′(Separate.

In Fig. 4, first, the output current (Q 31 is shown) at the current detector 22 at the prostitute η factory output'-I.
``31]-'', the output ``4'' in the steady operating state (-) is set to the required fuel flow rate X'-; This command value is then applied to, for example, an electro-pneumatic converter to drive and control the fuel flow control valve 9.

The third method for determining the required fuel flow rate function for 1° force current
This will be explained using figures. In Figure 3, draw a straight line 8. It is a -4 function that represents the fuel flow rate for electrochemical consumption due to the fuel flow. In addition, the curve shows the reformer catalyst Iθ quality at full, constant temperature 1
(To support F (- necessary (Qi side, with battery inlet 8
-1 绾成(-A・keru) It is a leapfrog J that indicates the flow of flames.

What should be noted here is that the output current from the two fuel chambers is +7. Also, if the catalyst temperature of the reformer is specified as C2, then C2 is different, then there is a complex sum as shown in A;7. That is, during standby operation, it is possible to resume operation without having to read the curve (by supplying υχ1;- to IL to stop the converter). From the above, the song P whose request for output (8, flow) is a flow word/function can be seen as a curve C, which is a combination of the straight line a and the curved line C.

The function of the required solvent flow rate for one output flow determined by
The width of the output current is set so as not to fall below the curve d in FIG. Fig. 3 shows the case in which no interruption occurs; however, in the case of interrupt

On the other hand, the fuel cell output requirements changed rapidly (at the 5th stage,
Fear: Considering that the output current of the 5 batteries is also subject to fluctuations in the same way as the output demand, as shown in FIG.
Input the output current change rate l2 to obtain the proportional
Request this fuel flow command value (2+/yT block) 3
4 to obtain a corrected requested fuel flow rate command value 35, which is used as a control command to the external fuel flow valve 9. By doing this, will the cell output and fuel reform be improved? Outside the field m: Responsiveness to negative and negative load changes can be improved. The several minute block 33 is 1^functional (as long as it can detect the two changing speeds IW, it is sufficient if it can detect two changing speeds IW. Perfect differential gain T: Imperfect differential time constant S Nira plus operator Next, temperature control of the reformer catalyst layer 4 will be explained using FIG. 6. The temperature of the catalyst layer 4 is detected by the exhaustion IJ3' detector 24. In Fig. 6, the detectors at three points are shown.
Increase or decrease the number of detectors as necessary. The average temperature of the detected catalyst layer temperatures 7u is calculated in an averaging block 36.

Or the number of catalyst layers is 6. High temperature of M degree detector
If you want to control the reverse, you can replace the averaging block with a maximum value selection 4 block, or (although it is not shown in Section 11), you can replace the averaging block and the maximum weight [5 selection - 7 block]. The averaged block output is used for normal control, and temperature control is suppressed only when the maximum value selection block output exceeds the standard 5.7?j7a degrees. It is also possible to adopt a control method that prevents the temperature from exceeding the temperature.The temperature signal processed in this way is reduced.
- input to block 37 and the other input temperature setpoint To
The difference is taken and input to the PID calculator 38 at the next stage. The PID calculator output 39 can be regarded as a fuel flow rate to the reformer 2 necessary to keep the temperature of the catalyst layer of the reformer 2 constant at a specified temperature: 1irli control signal.

On the other hand, in the fuel flow path system leading to the reformer 2, there is a
), there are various delay elements ≧e as described above.

What measures should be taken in the control system to compensate for this delay element? It is described in Figure F7. - The fuel flow rate on the fuel cell inlet side is detected by the C view detector 23. On the other hand, the fuel consumed in heavy oil is calculated by multiplying the output width and the flow coefficient by the coefficient block 40r. These two signals n, ↓), the remaining fuel flow rate signal 42 at the base block 41 (returning point) and outlet (ill) is obtained.This remaining fuel flow,
:il, i' times signal subtracter 45 and PID calculator 38
After performing a differential calculation with the 18 force 39, an integral block 43 having a refinement coefficient determined by the internal volume of the flow path from the fuel cell to the reformer burner 16 performs an integral calculation. The output 44 of this integral block 43 is calculated by furnace 71 for the internal volume C2 of the flow path from the smoke sting battery to the reformer burner C2.
The parent is set so that the output is 10 when 11 is full.

Immediately r, if the 6g charge replenishment is insufficient, the output 44 of the integral block 43 +i 1. If the value is less than o and the amount of raw material replenishment is excessive, it takes the value above OJU. The input to this integral block 43 is the output of the subtractor 45 mentioned earlier (=the output of the subtractor 45 mentioned above), and the body weight ratio of the remaining effective mosquitoes 1:1 to the total exhaust gas of the fuel chamber 7:L is the output current of the fuel cell. Since the parameter changes as the usage rate of Confucianism increases, the function generator 46 calculates the integral time in the integral block.
Determine the coefficient for the ringing and correct it using the multiplier 47 (and the output c 8j kt of the subtracter 45). In FIG. As a modification, the fuel flow rate signal or the fuel f1 flow rate command value which is the final output of the control system may be used). The value of the output 44 of the integration block 43 mentioned earlier is constantly monitored by the reset windup prevention logic 49, and if the output is less than O or more than 1.0+α, the input of the proportional divider is switched to the switching block 50. Controls the so-called reset windup prevention function of the integrator that is forced to zero. Furthermore, when the fuel cell power generation plant is stopped, the residual fuel in the system is purged using an inert gas or the like, so the integral value of the integral block 43 is forcibly reset to zero.

The signal 44 indicating the fuel replenishment amount described above is multiplied by the remaining fuel flow rate signal 42 in a multiplier 51 to obtain an expected value 52 of the reformer burner fuel flow rate signal. This signal is subtracted by a subtracter 53 from the output frequency 39 of the PID calculator 38 mentioned earlier, and then sent to a cascade calculator 54 to determine the fuel flow to keep the temperature of the catalyst layer of the reformer constant. Obtain a one-piece correction 'tii-55.

In FIG. 8, the fuel flow rate correction value 55 is added to the corrected requested fuel flow rate command value 35 described in l1iT in an adder 56 to create a comprehensive fuel temperature component command value 57, After performing flow rate and difference calculation, P1.D performance Jl???
At step 59, the health charge flow rate control command value is obtained. This command value is given upper and lower limiters (UL, LT) by the upper and lower limit limiter block 6 ( ) in the next stage, and then becomes a control command to the fuel flow rate control valve 9 . The lower limit value LL is expressed by a function that uses the output current of the fuel cell as a parameter at point L in FIG. 2, as shown by the straight line e in FIG. 3, and is expressed by the function generator 6 in FIG.
1 will be given. In addition, the upper limit value UL is determined by the line f in Figure 3, which represents point M in Figure 2 with the fuel cell output current as a parameter, and the higher value side of both functions of curve C (1), which represents the required fuel flow rate function with respect to the output current. In FIG. 8, an adder 62 adds or subtracts a constant C to the output of the billing fuel flow rate command function generator 32 for the output current to determine the upper limit function.

The function is shown in FIG. 3 as curve g.

If the above-mentioned inventions are collectively described, it will be shown in Figure 239.

As an uninvented modification, all the control blocks inside the box X in FIG. method is also possible. In this case, the output 39 of the I'ID calculator 38 means a fuel flow rate correction amount for maintaining the temperature of the I'J' layer of the reformer at the specified humidity.

〔Effect of the invention〕

The water supply invention has been explained in detail, but according to the present invention, the fuel utilization rate is set with a margin in mind, and the fuel flow rate is controlled based on this utilization rate, so the lower limit of the fuel supply amount can be set. It is possible to control the flow rate to ensure the same flow rate. In addition, since the control f of the fuel flow rate corresponds to the rate of change of the output current of the fuel cell, and the value t is used as a correction amount for flow rate control, the fuel flow rate can be adjusted to a value corresponding to the rate of change of the output current of the fuel cell. (Jl, it is possible to improve the responsiveness of salary.

[Brief explanation of drawings]

Figure 1 shows a schematic diagram of a fuel cell power generation system to which the present invention is applied, and Figure 2 shows the relationship between reactant utilization rate and output voltage of a heating cell. showing curved mouth,
Figure 3 shows the output current of the Shun 2 battery and the battery output current. Figures 4 and 5 are block diagrams showing different embodiments of the present invention, and Figures 61x1 and 7 are diagrams showing the relationship between the control device and A1. Block diagram, District 8 1. FIG. 9 is a block diagram 1 showing different embodiments of the present invention. 1 Raw fuel source, 2. Reformer, 9. Fuel flow rate control valve 10
・Fuel cell, 22...Current detector, 32...Function generator, 33...Differential block 34・Addition block I) Figure 4 Figure 5 Figure 6

Claims (3)

[Claims] (1) In a fuel cell power generation system comprising a fuel cell, a device for supplying air to the fuel cell, and a tank for storing hydrogen that is also supplied to the fuel cell and undergoes an electrochemical reaction with oxygen in the air. , a fuel utilization rate is determined that takes into account a predetermined margin of 1 from the upper limit of the utilization rate at which the output 'voltage, which decreases as the fuel utilization rate of the fuel cell increases, does not fall below a predetermined value, and a fuel utilization rate of 22 is determined. (2) A fuel cell consisting of a function generator that generates the corresponding fuel flow as a function of the flow as a parameter to the output '1□ of the fuel cell, and a transmission flow rate control valve that is controlled by the output of this function generator. Building material flow control device. (2) comprising a fuel cell, a device for supplying air to the fuel cell, and a fuel reformer for obtaining hydrogen from raw fuel that is also supplied to the fuel cell and undergoes an electrochemical reaction with oxygen in the air; In a fuel cell power generation system in which the residual fuel discharged from the fuel cell is used as a heating fuel for a fuel reformer to extract hydrogen from the aqueous fuel, the amount of electrochemical equivalent that sinks from the output WE flow of the building material battery is Fuel cell output current and the above 4. −
The fuel flow F: required to maintain the temperature of the Geo-1 reformer at a predetermined value (1) is the 4S charge year 1 cell output electric curtain, ゛・? Parameters are the leap fj, r and 1-1. the first, each occurring separately;
Second function Imao 2゛: And these bolts! 2) an adder that adds the outputs of the two generators; Taking into account the margin value, calculate the fuel flow cooling equivalent to the amount of 4(,>Fee usage>1.'<, ?g il, 7', %?l!t
The leap W generated as a function of the output current of
A fuel flow control device for a fuel cell, comprising a generator, a selection device for selecting the higher value side of the output of the function generator and the output of the adder, and a fuel flow rate control valve controlled by the output of the selection device. . (3) Claim 1, wherein a number corresponding to the rate of change of the output current is obtained by differentiation, incomplete differentiation, or difference calculation of the fuel cell output current, and this is added to the output of the function generator. Or the fuel flow control device for a fuel cell according to item 2.