JP2005276544A - Liquid delivery control system and fuel cell system utilizing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system suppressing increase in cost and enhancing reliability by controlling a reforming pump based on a rate of change of water pressure in a water storage device measured with an inexpensive reliable manometer. <P>SOLUTION: The fuel cell system is equipped with a reformer 20 forming reformed gas from supplied fuel and reforming water and supplying to a fuel cell, the water storage device 50 storing reforming water, a reforming water pump 53 sending the reforming water stored in a water storage device 50, the manometer 51 measuring water pressure in the water storage device 50, and a control device feedback-controlling the reforming water pump 53 based on the rate of change of water pressure measured with the manometer 51. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid delivery control system for delivering a liquid from a liquid tank that stores the liquid, and in particular, a reformed gas and air generated from fuel and reformed water supplied to a reformer, and a combustion cell. The present invention relates to control of a reforming water pump that supplies reforming water to a reformer in a fuel cell system that generates power by supplying to the fuel cell.

  As a fuel cell system, the cooling water circulation system 4 that recovers the heat generated by the fuel cell 1 and the CO converter 3 and keeps them at a predetermined operating temperature is provided with a water vapor separator 5, and the separated steam 8 is added to the raw fuel. In addition, there is known one that supplies the fuel reformer 2 and supplies it to an external heat utilization facility 16 as a heat medium (Patent Document 1). In this fuel cell system, as shown in FIG. 2 of Patent Document 1, the water level in the water vapor separator 5 is detected by the water level detector, and the liquid level is lowered from the set water level by the detection signal. A level control unit 17 that senses the above-described operation controls the supply of pure water intermittently by opening and closing the valve 14 to maintain the liquid level in the water vapor separator at the set level. (Patent Document 1 [0002] to [0003]). In this case, since replenishment of pure water is intermittently controlled, water supply is started when the water level in the water vapor separator 5 becomes low, and water supply is stopped when the water level returns to the set level. The temperature and pressure in the water vapor separator 5 fluctuate in accordance with the cycle of the water supply, and the supply amount of the steam periodically changes due to this, and the fuel reformer 2 and the heat using the stable heat amount as a heat load. There arises a problem that the supply equipment 16 cannot be supplied.

As shown in FIG. 1 of Patent Document 1, the fuel cell system that solves this problem is a water supply control that continuously controls the amount of water supplied to the steam separator 5 in proportion to the amount of steam supplied. Means including, for example, a main controller 21 which receives the detection signals of the steam flow detectors 25 and 26 and the detection signal of the feed water flow detector 27 and issues a primary operation command of the feed water adjustment valve 24, or a water level detector 28 The sub-regulator 22 which issues the secondary operation command which correct | amended the water supply amount corresponding to this detected water level is included ([0010]-[0012] of patent document 1).
Japanese Patent Laid-Open No. 06-275294 (pages 2, 3 and 1, 2)

  In the fuel cell system described in Patent Document 1 [0010] to [0012] described above, the steam flow detector 25 and the water level detector 28 are used. That is, since the flowmeter is generally expensive, there is a problem that the cost of the entire system increases. In addition, since the flow meter is a delicate device, it easily breaks down, and thus there is a problem that it is difficult to improve the reliability of the system.

  The present invention has been made to solve the above-described problems, and controls a reforming water pump based on a rate of change of water pressure in a water reservoir measured using an inexpensive and reliable pressure gauge. Thus, an object of the present invention is to provide a fuel cell system and a liquid delivery control system that suppresses an increase in cost and has high reliability.

  In order to solve the above-described problems, the structural feature of the invention according to claim 1 is that a liquid tank for storing a liquid and a liquid stored in the liquid tank for use equipment that uses the liquid. It is provided with a delivery means for delivering, a pressure gauge for measuring the pressure in the liquid tank, and a control means for feedback-controlling the delivery means based on the rate of change of the pressure measured by this pressure gauge.

  Further, the structural feature of the invention according to claim 2 is that, in claim 1, the control means derives the rate of change of pressure based on the pressure measured by the pressure gauge, and the rate of change derivation means. A delivery amount deriving means for deriving the delivery amount of the delivery means based on the rate of change of pressure derived by the control means, and the control means controls the delivery amount derived by the delivery amount deriving means to be a target delivery amount. It is.

  The structural features of the invention according to claim 3 are: a reformer that generates reformed gas from the supplied fuel and reformed water and supplies the reformed gas to the fuel cell; and a reservoir that stores the reformed water. , A reforming water pump that sends the reforming water stored in the reservoir to the reformer, a pressure gauge that measures the water pressure in the reservoir, and the rate of change of the water pressure measured by the pressure gauge. And a control means for feedback-controlling the reforming water pump.

  According to a fourth aspect of the present invention, in the configuration of the third aspect, the control means includes a change rate deriving means for deriving a water pressure change rate based on the water pressure measured by the pressure gauge, and the change rate deriving means. A delivery amount deriving means for deriving the delivery amount of the reforming water pump based on the rate of change of the water pressure derived by the control unit, and a reforming water pump so that the delivery amount derived by the delivery amount deriving means is a target delivery amount. And a pump control means for controlling.

  In the invention according to claim 1 configured as described above, the control means is stored in the liquid tank based on the rate of change in pressure measured by the pressure gauge that measures the pressure in the liquid tank. The feeding means for sending the liquid that is being used to the equipment that uses the liquid is feedback-controlled. The measured pressure is proportional to the amount of water in the liquid tank, and increases or decreases according to the amount of liquid flowing in and out of the liquid tank. That is, the flow rate of liquid in and out of the liquid tank is proportional to the rate of change of pressure. Therefore, it is possible to feedback control the delivery means based on the rate of change in pressure proportional to the liquid flow rate of the liquid tank. A pressure gauge for measuring the pressure in the liquid tank is generally an inexpensive device, and the inexpensive means is used to control the delivery means, so that the cost increase of the entire liquid delivery control system is suppressed. be able to. In addition, the pressure gauge is generally a highly reliable device, and since the highly reliable device is used to control the delivery means, the reliability of the liquid delivery control system can be improved.

  In the invention according to claim 2 configured as described above, the change rate deriving unit derives the water pressure change rate based on the pressure measured by the pressure gauge, and the delivery amount deriving unit is derived by the change rate deriving unit. Since the delivery amount of the delivery means is derived based on the water pressure change rate, and the control means controls the delivery means so that the delivery amount derived by the delivery amount derivation means is the target delivery amount, the delivery means can be reliably and easily Can be controlled.

  In the invention which concerns on Claim 3 comprised as mentioned above, a control means feedback-controls a reforming water pump based on the change rate of the water pressure measured by the pressure gauge which measures the water pressure in a water reservoir. The measured water pressure is proportional to the amount of water in the reservoir and increases or decreases according to the amount of water in and out of the reservoir. That is, the flow rate of water in and out of the water reservoir is proportional to the rate of change in water pressure. Therefore, the reforming water pump can be feedback controlled based on the rate of change of the water pressure proportional to the outflow rate of the water in the water reservoir. A pressure gauge that measures the water pressure in the water reservoir is generally an inexpensive device, and this inexpensive device is used to control the reforming water pump, thus suppressing an increase in the cost of the entire fuel cell system. be able to. The pressure gauge is generally a highly reliable device, and the reforming water pump is controlled using this highly reliable device, so that the reliability of the fuel cell system can be improved.

  In the invention according to claim 4 configured as described above, the change rate deriving unit derives the water pressure change rate based on the water pressure measured by the pressure gauge, and the delivery amount deriving unit is derived by the change rate deriving unit. Since the reforming water pump is controlled so that the delivery amount of the reforming water pump is derived based on the rate of change of the water pressure and the pump control means uses the delivery amount derived by the delivery amount deriving means as the target delivery amount. The reforming water pump can be easily controlled.

  Hereinafter, an embodiment of a fuel cell system to which a liquid delivery control system according to the present invention is applied will be described. FIG. 1 is a schematic diagram showing an outline of this fuel cell system. The fuel cell system includes a fuel cell 10 and a reformer 20 that generates a reformed gas containing hydrogen gas necessary for the fuel cell 10.

  The fuel cell 10 includes a fuel electrode 11, an air electrode 12, and an electrolyte 13 interposed between both electrodes 11, 12. The reformed gas supplied to the fuel electrode 11 and the air supplied to the air electrode 12 ( (Cathode air) is used to generate electricity. In the present embodiment, the case where the fuel cell 10 is a polymer electrolyte fuel cell will be described. Therefore, the electrolyte 13 is an ion exchange membrane (particularly a cation exchange membrane), and the fuel is natural gas or methanol.

  In the fuel electrode 11, the supplied hydrogen gas reacts as shown in the following chemical formula 1, and the product hydrogen ions are supplied to the air electrode 12 through the electrolyte 13 and the anode containing unreacted hydrogen gas. Off-gas is discharged. In the air electrode 12, oxygen in the supplied air and hydrogen ions supplied from the fuel electrode 11 through the electrolyte 13 react as shown in the following chemical formula 2 to generate water (water vapor) and include the water vapor. The cathode off gas is discharged.

(Chemical formula 1)
H ₂ → 2H ⁺ + 2e ⁻
(Chemical formula 2)
2H ⁺ + 1 / 2O ₂ + 2e ⁻ → H ₂ O
Here, the electrons generated in the fuel electrode 11 reach the air electrode 12 through a circuit (inverter circuit) connected to the outside, and the reaction shown in the chemical formula 2 is performed using the electrons in the air electrode 12. As a result, the fuel cell 10 generates power.

  A supply pipe 61 that supplies air and a discharge pipe 62 that discharges cathode off-gas are connected to the air electrode 12 of the fuel cell 10. Air is humidified in the middle of the supply pipe 61 and the discharge pipe 62. A humidifier 14 is provided. The humidifier 14 is of a water vapor exchange type and dehumidifies water vapor in the gas discharged from the discharge pipe 62, that is, from the air electrode 12, and supplies the water vapor into the supply pipe 61, that is, air supplied to the air electrode 12. And humidify.

  The reformer 20 steam-reforms fuel such as natural gas, LP gas, kerosene, methanol, etc., and supplies hydrogen-rich reformed gas to the fuel cell 10. It is composed of a carbon oxide shift reaction part (hereinafter referred to as a CO shift part) 23 and a carbon monoxide selective oxidation reaction part (hereinafter referred to as a CO selective oxidation part) 24. In the present embodiment, the reformer 20 is a utilization device that uses the liquid (reformed water) stored in the liquid tank (water reservoir 50).

  The burner 21 is supplied with combustion fuel and combustion air from the outside during start-up, or anode off-gas (reformed gas discharged to the fuel cell and not used) from the fuel electrode 11 of the fuel cell 10 during steady operation. Is supplied, the supplied gas is combusted, and the combustion gas is led out to the reforming section 22. This combustion gas heats the reforming section 22 (so that it becomes the activation temperature range of the catalyst of the reforming section 22), and then the water vapor contained in the combustion gas is condensed through the combustion gas condenser 34. And exhausted to the outside. The combustion gas condenser 34 communicates with a deionizer 40 described later via a pipe 63.

  The reforming unit 22 reforms a mixed gas obtained by mixing the fuel supplied from the outside with water vapor (reformed water) from the evaporator 25 by using a catalyst charged in the reforming unit 22 to generate hydrogen gas and carbon monoxide. Gas is generated (so-called steam reforming reaction). At the same time, carbon monoxide and steam generated by the steam reforming reaction are converted into hydrogen gas and carbon dioxide (so-called carbon monoxide shift reaction). These generated gases (so-called reformed gas) are led to the CO shift unit 23.

  The CO shift unit 23 is converted into hydrogen gas and carbon dioxide gas by reacting carbon monoxide and water vapor contained in the reformed gas with a catalyst filled therein. Thus, the reformed gas is led to the CO selective oxidation unit 24 with the carbon monoxide concentration reduced.

  The CO selective oxidation unit 24 generates carbon dioxide by reacting carbon monoxide remaining in the reformed gas with CO purification air further supplied from the outside using a catalyst filled therein. . As a result, the reformed gas is further reduced in carbon monoxide concentration (10 ppm or less) and is led to the fuel electrode 11 of the fuel cell 10.

  The evaporator 25 is disposed in the middle of the reforming water supply pipe 68 having one end disposed in the water reservoir 50 and the other end connected to the reforming unit 22. The reforming water supply pipe 68 is provided with a reforming water pump 53 serving as a sending means. The pump 53 is controlled by a control device 70 and pumps recovered water used as reforming water in the water reservoir 50 to the evaporator 25. The evaporator 25 is heated by, for example, the combustion gas discharged from the burner 21, the heat of the reforming unit 22, the CO shift unit 23, and the like, thereby steaming the reformed water fed under pressure.

  A condenser 30 is provided in the middle of a pipe 64 that connects the CO selective oxidation unit 24 of the reformer 20 and the fuel electrode 11 of the fuel cell 10. The condenser 30 is an integral structure in which a reformed gas condenser 31, an anode offgas condenser 32, and a cathode offgas condenser 33 are integrally connected. The reformed gas condenser 31 condenses water vapor in the reformed gas supplied to the fuel electrode 11 of the fuel cell 10 flowing in the pipe 64. The anode off-gas condenser 32 is provided in the middle of a pipe 65 that communicates the fuel electrode 11 of the fuel cell 10 and the burner 21 of the reformer 20, and the fuel electrode 11 of the fuel cell 10 that flows in the pipe 65. Water vapor in the anode off-gas discharged from is condensed. The cathode offgas condenser 33 is provided downstream of the humidifier 14 in the discharge pipe 62, and condenses the water vapor in the cathode offgas discharged from the air electrode 12 of the fuel cell 10 flowing in the discharge pipe 62. The condenser 30 is supplied with a low-temperature liquid in a hot water tank (not shown) or a liquid cooled by a radiator and a cooling fan, and condenses water vapor in each gas by heat exchange with the liquid. ing.

  These condensers 31, 32, and 33 communicate with the pure water device 40 through the pipe 66, and the condensed water condensed in each of the condensers 31, 32, and 33 is led out to the pure water device 40 and collected. It has become so. The deionizer 40 converts the condensed water supplied from the condenser 30 and the combustion gas condenser 34, that is, the recovered water into pure water using a built-in ion exchange resin, and the purified water is converted into the water reservoir 50. Is derived. A pipe 67 for introducing makeup water (tap water) supplied from a tap water supply source (for example, a water pipe) is connected to the deionizer 50, and the amount of water stored in the deionizer 50 has a lower limit water level. Below that, tap water is supplied.

  A water reservoir 50 that is a liquid tank temporarily stores (stores) the recovered water derived from the pure water device 40 as reformed water that is a liquid. A pressure gauge 51 is disposed at the bottom of the water reservoir 50. The pressure gauge 51 measures the water pressure (pressure) in the water reservoir 50, and the measurement signal is sent to the control device 70. The pressure gauge 51 can detect the water pressure at the water level where the detection unit for detecting the water pressure is located. Therefore, when the pressure gauge 51 is provided in contact with the inner wall of the bottom surface so that the detection unit is disposed at the lowermost part of the water reservoir 50, the water pressure of the total amount of water in the water reservoir 50 can be measured. If the pressure gauge 51 is provided so as to be arranged at a predetermined height from the lowermost part, the water pressure of the water amount up to that height can be measured. In the present embodiment, the pressure gauge 51 is provided in contact with the inner wall of the bottom surface. The pressure gauge 51 may be disposed at a predetermined height from the lowermost part of the water reservoir 50. In this case, the predetermined height may be set to the lower limit water level. According to this, when the detection signal of the pressure gauge 51 becomes 0, it can be determined that the recovered water in the water reservoir 50 is at the lower limit water level, so that the lower limit of the recovered water can be detected without the trouble of calculating.

  Further, the pressure gauge 51 and the reforming water pump 53 described above are connected to the control device 70 (see FIG. 2). The control device 70 includes a microcomputer (not shown), and the microcomputer includes an input / output interface, a CPU, a RAM, and a ROM (all not shown) connected via a bus. The CPU executes a program corresponding to the flowchart of FIG. 3 to perform feedback control of the reforming water pump 53. The RAM temporarily stores variables necessary for executing the program, and the ROM stores the program.

  Next, the operation of the fuel cell system described above will be described with reference to FIG. When a start switch (not shown) is turned on, the control device 70 executes the program shown in FIG. 3 every predetermined unit time. The control device 70 derives the water pressure change rate based on the water pressure measured by the pressure gauge 51 every time this program is started (change rate deriving means). That is, in step 102, the control device 70 measures the water pressure in the water reservoir 50 with the pressure gauge 51 and stores the measured value. In step 104, a water pressure change rate ΔP is derived from the water pressure measured and stored last time and the water pressure measured this time. Specifically, the difference in water pressure measured last time and this time is divided by a predetermined unit time. The water pressure change rate ΔP may be an average of a plurality of recently derived (for example, 10) times.

一方、底面の受ける初めの水圧Ｐ１は、下記数２に示すように、比重×（底面積Ｓ×水位Ｈ１）／底面積Ｓで演算され、汲みだし後の水圧Ｐ２は下記数３に示すように演算される。なお水の比重を１とする。

上記数２および数３の結果を上記数１に代入すると、上記数１は下記数４のように変形される。

したがって、測定された水圧は貯水器５０内の貯水量（厳密には圧力計より上位の貯水量）に比例しており、貯水器の水の出入量に応じて増減する。すなわち、貯水器５０の水の出入流量は水圧の変化率に比例する。このことを利用して、制御装置７０は、ステップ１０６において、上記数４から貯水器５０から導出されている改質水の流量Ｖｗ、すなわち改質水ポンプ５３の実際の送出量を導出する（送出量導出手段）。そして、制御装置７０は、ステップ１０８において、ステップ１０６にて導出された送出量（流量Ｖｗ）を目標送出量（例えば１０ｃｃ／ｍｉｎ）とするように改質水ポンプ５３をフィードバック制御する。 Here, the relationship between the water pressure change rate ΔP and the flow rate Vw will be described. Water is contained in a box-shaped container having a bottom area S up to a water level H1. The pump is operated for a predetermined time T, and water is pumped out until the water level becomes H2. In this case, the flow rate Vw is calculated by dividing the amount of water pumped out, that is, the bottom area S × the reduced water level H1-H2 by the pumping time T, as shown in the following equation (1).

On the other hand, the initial water pressure P1 received by the bottom surface is calculated by specific gravity × (bottom area S × water level H1) / bottom area S as shown in the following equation 2, and the water pressure P2 after pumping is expressed by the following equation 3. Is calculated. The specific gravity of water is 1.

Substituting the results of the above equations 2 and 3 into the above equation 1, the above equation 1 is transformed into the following equation 4.

Therefore, the measured water pressure is proportional to the amount of water stored in the water reservoir 50 (strictly, the amount of water stored above the pressure gauge), and increases or decreases according to the amount of water in and out of the water reservoir. That is, the flow rate of water in and out of the water reservoir 50 is proportional to the rate of change in water pressure. Using this, in step 106, the control device 70 derives the flow rate Vw of the reforming water derived from the water reservoir 50 from Equation 4 above, that is, the actual delivery amount of the reforming water pump 53 ( Delivery amount deriving means). In step 108, the control device 70 feedback-controls the reforming water pump 53 so that the delivery amount (flow rate Vw) derived in step 106 is set to the target delivery amount (for example, 10 cc / min).

  As can be understood from the above description, in this embodiment, the control device 70 controls the reforming water pump 53 based on the rate of change of the water pressure measured by the pressure gauge 51 that measures the water pressure in the water reservoir 50. Feedback control. Therefore, the pressure gauge 51 for measuring the water pressure in the reservoir 50 is generally an inexpensive device, and the reforming water pump 53 is controlled using this inexpensive device. An increase in cost can be suppressed. The pressure gauge 51 is generally a highly reliable device, and the reforming water pump 53 is controlled using this highly reliable device, so that the reliability of the fuel cell system can be improved. it can.

  Further, the water pressure change rate ΔP is derived based on the water pressure measured by the pressure gauge 51 in steps 102 and 104, and the actual delivery amount Vw of the reforming water pump 53 is derived based on the water pressure change rate Δ in step 106. In step 108, the reforming water pump 53 is controlled so that the delivery amount Vw becomes the target delivery amount, so that the reforming water pump 53 can be reliably and easily controlled to the target delivery amount.

  In the present embodiment, since the pressure gauge 51 is provided at the bottom of the liquid tank (reservoir 50), almost all liquid (reformed water) in the liquid tank can be used. There is an advantage that it is not easily affected by the fluctuation of the liquid level. However, it does not necessarily have to be provided at the bottom. When control is performed so that a predetermined amount of liquid always remains in the liquid tank, the liquid tank may be provided on the side surface of the liquid tank having a height equal to or lower than the predetermined amount.

  In addition, it is preferable that the liquid tank has a constant horizontal cross-sectional area because the correlation between the liquid delivery amount and the pressure change rate is linear, so that the calculation of the delivery amount can be simplified. However, even if the correlation between the liquid delivery amount and the pressure change rate is not linear, if the correlation between the height of the liquid level in the liquid tank and the pressure is stored in advance in a map or the like, the shape of the horizontal cross-sectional area is not constant. It can also be used in liquid tanks.

  In the above-described embodiment, the liquid delivery control system is used for delivery control of reformed water. However, the present invention is not limited to this, and delivery control of other liquids sent from the liquid tank to the liquid utilization device. Can also be used. For example, in a fuel cell system, it can be used for sending out humidified water for humidifying a gas supplied to the fuel cell, and when a liquid fuel such as methanol is used as the fuel sent to the reformer, or the fuel electrode of the fuel cell. In the case of supplying liquid fuel such as methanol to the tank, it can be used for delivery control of the liquid fuel.

  Also by this, the control means converts the liquid stored in the liquid tank to the utilization device using this liquid based on the rate of change of the pressure measured by the pressure gauge that measures the pressure in the liquid tank. The sending means for sending is feedback-controlled. The measured pressure is proportional to the amount of water in the liquid tank, and increases or decreases according to the amount of liquid flowing in and out of the liquid tank. That is, the flow rate of liquid in and out of the liquid tank is proportional to the rate of change of pressure. Therefore, it is possible to feedback control the delivery means based on the rate of change in pressure proportional to the liquid flow rate of the liquid tank. A pressure gauge for measuring the pressure in the liquid tank is generally an inexpensive device, and the inexpensive means is used to control the delivery means, so that the cost increase of the entire liquid delivery control system is suppressed. be able to. In addition, the pressure gauge is generally a highly reliable device, and since the highly reliable device is used to control the delivery means, the reliability of the liquid delivery control system can be improved. The rate-of-change deriving unit derives the water pressure change rate based on the pressure measured by the pressure gauge, and the amount-of-feeding deriving unit derives the delivery amount of the sending unit based on the water pressure change rate derived by the rate-of-change deriving unit. Since the control unit controls the sending unit so that the sending amount derived by the sending amount deriving unit is set as the target sending amount, the sending unit can be controlled reliably and easily.

1 is a schematic diagram showing an outline of an embodiment of a fuel cell system according to the present invention. It is a block diagram which shows the fuel cell system shown in FIG. It is a flowchart of the control program performed with the control apparatus shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 11 ... Fuel electrode, 12 ... Air electrode, 20 ... Reformer, 21 ... Burner, 22 ... Reformer, 23 ... Carbon monoxide shift reaction part (CO shift part), 24 ... Carbon monoxide Selective oxidation reaction section (CO selective oxidation section), 25 ... evaporator, 30 ... condenser, 31 ... reformer gas condenser, 32 ... anode off-gas condenser, 33 ... cathode off-gas condenser, 34 ... combustion gas Condenser, 40 ... pure water device, 50 ... water reservoir, 51 ... pressure gauge, 53 ... reforming water pump, 61-67 ... piping, 68 ... reforming water supply pipe.

Claims (4)

A tank for storing liquid, and
A delivery means for delivering the liquid stored in the liquid tank to a utilization device using the liquid;
A pressure gauge for measuring the pressure in the liquid tank;
A liquid delivery control system comprising: control means for feedback-controlling the delivery means based on a rate of change in pressure measured by the pressure gauge. The control means according to claim 1,
Change rate deriving means for deriving a pressure change rate based on the pressure measured by the pressure gauge;
A delivery amount deriving unit for deriving the delivery amount of the delivery unit based on the pressure change rate derived by the change rate deriving unit;
The liquid delivery control system, wherein the control means controls the delivery amount derived by the delivery amount derivation means to be a target delivery amount. A reformer that generates reformed gas from the supplied fuel and reformed water and supplies the reformed gas to the fuel cell;
A water reservoir for storing the reformed water;
A reforming water pump for sending the reforming water stored in the water reservoir to the reformer;
A pressure gauge for measuring the water pressure in the reservoir;
A fuel cell system comprising control means for feedback-controlling the reforming water pump based on a rate of change in water pressure measured by the pressure gauge. In Claim 3, the control means includes:
Change rate deriving means for deriving a water pressure change rate based on the water pressure measured by the pressure gauge;
A delivery amount deriving unit for deriving the delivery amount of the reforming water pump based on the water pressure change rate derived by the change rate deriving unit;
A fuel cell system comprising: pump control means for controlling the reforming water pump so that the delivery quantity derived by the delivery quantity deriving means is a target delivery quantity.

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