CN1717831A

CN1717831A - Fuel cell system and correlation technique

Info

Publication number: CN1717831A
Application number: CNA2003801002521A
Authority: CN
Inventors: 的场雅司; 小幡武昭
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 2002-11-13
Filing date: 2003-10-23
Publication date: 2006-01-04
Anticipated expiration: 2023-10-23
Also published as: CN100468848C

Abstract

The invention discloses a kind of fuel cell system and correlation technique, have based on status signal and implement the system controller (37) that enthalpy calculates, thereby the ignition temperature of forecast combustion chamber (7) during cleaning, this status signal relates to anode exhaust and cathode exhaust gas, and is detected by Temperature Detector (29), pressure detector (30) and moisture detector (31).Ignition temperature in prediction surpasses in limited time, and the cathode exhaust gas volume increases, thereby the ignition temperature of combustion chamber (7) is limited to below the higher limit.

Description

Fuel cell system and correlation technique

Technical field

The present invention relates to fuel cell system, more specifically to the fuel cell system that improved chamber temperature control is provided for the burning anode exhaust, with and related methods.

Background technology

In fuel cell system, carry out electrochemical reaction such as the fuel gas of hydrogen and the oxidant gas that comprises oxygen each other by electrolyte, emit electric energy from the electrode that is placed in the electrolyte two sides.Especially, as the power supply of motor vehicle, use the solid polymer fuel cell of solid electrolyte to be subjected to common attention with handling easily because of its low operating temperature.The vehicle of fuel cell-driven is the vehicle that cleans most, has only water as emission of substance and residual.This vehicle is installed the absorption of hydrogen unit, for example high pressure hydrogen tank, liquified hydrogen gas tank, and the amorphous alloy jar that absorbs hydrogen.Be transported to the fuel cell from the hydrogen and the oxygenous air of the supply of hydrogen absorptive unit, finish reaction, thereby from fuel cell, discharge electric energy to drive the motor that is connected with driving wheel.

Solid polymer fuel cell comprises the anode exhaust recirculation type, and the anode exhaust that wherein comprises the unreacting hydrogen of discharging from anode export is recycled to anode inlet.The type fuel cell comprises anode (fuel electrode) inlet of supply of hydrogen, flow velocity greater than with the electrochemical reaction of anode exhaust in the hydrogen flow rate that consumes.

When this anode recirculation type fuel cell continued operation, because air and steam leak from negative electrode (air electrode), so nitrous oxides concentration in the anode exhaust and vapour concentration increase.In addition, comprise impurity if form the hydrogen of fuel gas, different with hydrogen, they accumulate in the anode exhaust, do not consume in electrochemical reaction.

These phenomenons have reduced the performance that electric energy produces inadvisablely.Therefore, after continued operation a period of time, the anode exhaust that will comprise a large amount of impurity from anode exhaust recirculation unit is discharged to the outer cylinder, and the burning of anode exhaust and air takes place therein to a certain extent.

Use the combustion chamber of Japanese Patent Application Publication special permission (Laid-Open) 8-7803 suggestion, the flow velocity of control air, the temperature of consequently controlling the combustion chamber is no more than heat resisting temperature.

Under this technology, fuel cell system comprises the fuel reformer that forms with the combustion chamber, and anode exhaust and cathode exhaust gas are introduced into wherein and burning; With cathode exhaust gas turbine driven air compressor; And make air and the air carried is introduced into the low temperature air blast of combustion chamber together from air compressor.

In addition, this fuel cell system comprises based on the outlet temperature of the oxygen concentration of fuel cell output command, burning and gas-exhausting and combustion chamber gives the order of low temperature air blast output speed, and gives the controller of reformer-combustion chamber-air velocity regulator valve output opening degree (opening degree) corrective command.If the outlet temperature of combustion chamber surpasses the upper limit, according to the opening degree that is supplied to the reformer combustion chamber to be produced with the air velocity increase that reduces chamber temperature, the rotating speed of opening degree that controller control reformer-combustion chamber-air velocity regulator valve is to be increased and low temperature air blast to be increased.

Summary of the invention

But,, increase the structure that air velocity reduces the temperature of combustion chamber if above-mentioned technology has the higher limit that the detected value of combustor exit temperature surpasses temperature.Therefore, when carrying out the burning of discontinuity and short-term in the combustion chamber, the temperature of Outlet Gas Temperature rises owing to the thermal capacitance that exists in the combustion chamber reduces.Therefore, because can not detect ignition temperature, so the performance of combustion chamber reduces above temperature upper limit.

In order to address this problem, one aspect of the present invention is a fuel cell system, comprises the fuel gas feeding unit of fuel supplying gas; The oxidant gas feeding unit of supply oxidant gas; Use fuel gas and oxidant gas to produce the fuel battery of electric energy; The anode exhaust that will go out from the anode exhaust of fuel battery is recycled to the anode exhaust recirculation unit on the anode; Interim from anode exhaust recirculation unit with the cleaning unit of anode exhaust gas discharge to its outside; At least burn the anode exhaust of from cleaning unit, discharging, from the oxidant gas of fuel battery cathode exhaust and the combustion chamber of cathode exhaust gas, carry out the system controller of system's control operation, make that the ignition temperature of combustion chamber is no more than to fixed temperature when allowing cleaning unit to combustion chamber discharging anode exhaust.

According to a further aspect in the invention, provide a kind of method of controlling fuel cell system, this method comprises the fuel gas feeding unit of preparation fuel supplying gas; The oxidant gas feeding unit of supply oxidant gas; Use fuel gas and oxidant gas to produce the fuel battery of electric energy; At least burn from the anode exhaust of anode exhaust gas discharge, and from the oxidant gas of fuel battery cathode exhaust or the combustion chamber of cathode exhaust gas; Anode exhaust anode exhaust from fuel battery; Recirculation from the air supply unit or the anode exhaust of fuel battery anode exhaust to anode; At least burn from the anode exhaust of fuel battery anode exhaust and from the oxidant gas or the cathode exhaust gas of fuel battery cathode exhaust; And executive system control, so that when allowing anode exhaust to be discharged into the combustion chamber, the ignition temperature of combustion chamber is no more than to fixed temperature.

Description of drawings

Fig. 1 is the system construction drawing of setting forth the fuel cell system first embodiment structure according to the present invention.

Fig. 2 A to 2E sets forth the time diagram of ignition temperature control in the first embodiment, and wherein, Fig. 2 A represents the ignition temperature Te of combustion chamber 7; Fig. 2 B represents the flow velocity of air supply unit 2 air supplied; Fig. 2 C represents the rate of discharge of cathode exhaust gas; Fig. 2 D represents the flow velocity of the hydrogen of hydrogen supply unit 1 supply; And Fig. 2 E represents the rate of discharge of anode exhaust.

Fig. 3 is the flow chart of setting forth the system controller control content that forms first an embodiment part.

Fig. 4 is the system construction drawing of setting forth the fuel cell system second embodiment structure according to the present invention.

Fig. 5 A to 5E is the time diagram that is set forth in ignition temperature control in second embodiment, and wherein, Fig. 5 A represents the ignition temperature Te of combustion chamber 7; Fig. 5 B represents the flow velocity of air supply unit 2 air supplied; Fig. 5 C represents the rate of discharge of cathode exhaust gas; Fig. 5 D represents the flow velocity of the hydrogen of hydrogen supply unit 1 supply; And Fig. 5 E represents the rate of discharge of anode exhaust.

Fig. 6 is the flow chart of setting forth the system controller control content that forms second an embodiment part.

Fig. 7 is the system construction drawing of setting forth fuel cell system the 3rd embodiment structure according to the present invention.

Fig. 8 A to 8E is the time diagram that is set forth in ignition temperature control in the 3rd embodiment, and wherein, Fig. 8 A represents the ignition temperature Te of combustion chamber 7; Fig. 8 B represents the flow velocity of auxiliary air 28 air supplied; Fig. 8 C represents the rate of discharge of cathode exhaust gas; Fig. 8 D represents the flow velocity of the hydrogen of hydrogen supply unit 1 supply; And Fig. 8 E represents the rate of discharge of anode exhaust.

Fig. 9 is the flow chart of setting forth the system controller control content that forms the 3rd an embodiment part.

Figure 10 A to 10D is the time diagram that is set forth in ignition temperature control in the 4th embodiment, and wherein, Figure 10 A represents the ignition temperature Te of combustion chamber 7; Figure 10 B represents the rate of discharge of cathode exhaust gas; Figure 10 C represents the flow velocity of the hydrogen of hydrogen supply unit 1 supply; And Figure 10 D represents the rate of discharge of anode exhaust.

Figure 11 is the flow chart of setting forth the system controller control content that forms the 4th an embodiment part.

Figure 12 A to 12E is the time diagram that is set forth in ignition temperature control in the 5th embodiment, and wherein, Figure 12 A represents the ignition temperature Te of combustion chamber 7; Figure 12 B represents the flow velocity of air supply unit 2 air supplied; Figure 12 C represents the rate of discharge of cathode exhaust gas; Figure 12 D represents the flow velocity of the hydrogen of hydrogen supply unit 1 supply; And Figure 12 E represents the rate of discharge of anode exhaust.

Figure 13 is the flow chart of setting forth the system controller control content that forms the 5th an embodiment part.

Figure 14 is the system construction drawing of setting forth fuel cell system the 6th embodiment structure according to the present invention.

Figure 15 A to 15E is the time diagram that is set forth in ignition temperature control in the 6th embodiment, and wherein, Figure 15 A represents the ignition temperature Te of combustion chamber 7; Figure 15 B represents the delivery rate of water; Figure 15 C represents the rate of discharge of cathode exhaust gas; Figure 15 D represents the flow velocity of the hydrogen of hydrogen supply unit 1 supply; And Figure 15 E represents the rate of discharge of anode exhaust.

Figure 16 is the flow chart of setting forth the system controller control content that forms the 6th an embodiment part.

Figure 17 is the view of setting forth the ignition temperature prognostic chart in fuel battery operation condition mode.

Figure 18 A to 18E is the time diagram that is set forth in ignition temperature control in the 7th embodiment, and wherein, Figure 18 A represents the ignition temperature Te of combustion chamber 7; Figure 18 B represents the flow velocity of air supply unit 2 air supplied; Figure 18 C represents the rate of discharge of cathode exhaust gas; Figure 18 D represents the flow velocity of the hydrogen of hydrogen supply unit 1 supply; And Figure 18 E represents the rate of discharge of anode exhaust.

Figure 19 is the flow chart of setting forth the system controller control content that forms the 7th an embodiment part.

Figure 20 is set forth in to be used for the calculating voltage threshold value in the 7th embodiment, thereby judges the view of finding whether to implement the tables of data that anode exhaust cleans.

Figure 21 is set forth in to be used for the calculating voltage threshold value in the 7th embodiment, thereby judges the view of finding whether to implement the tables of data that anode exhaust cleans.

Figure 22 is the view that is set forth in the tables of data that is used for calculating the air velocity rate of change in the 7th embodiment.

Figure 23 is the view that is set forth in the tables of data that is used for calculating the air velocity rate of change in the 7th embodiment.

Figure 24 is the view that is set forth in the tables of data that is used for calculating the air velocity rate of change in the 7th embodiment.

Embodiment

(first embodiment)

Consult Fig. 1 to 3, describe first embodiment below in detail according to fuel cell system of the present invention.

Fig. 1 is the system construction drawing of setting forth the first embodiment structure.Among the figure, fuel cell system comprises the act as a fuel hydrogen supply unit 1 (fuel gas feeding unit) of gas of supply of hydrogen; The supply air is as the air supply unit 2 (oxidant gas feeding unit) of oxidant gas; Comprise the electrode that produces electric energy, for example distinguish supply of hydrogen and the anode 4 of air and the fuel battery 3 of negative electrode 5; Make the anode exhaust for the treatment of recirculation arrive the anode exhaust recirculation unit 6 of anode 4 upstream sides by anode exhaust recycling pipe 12; Between the starting period, use the coolant heat exchanger 8 of the burning and gas-exhausting heats coolant of combustion chamber 7; Coolant cools unit 9; Make hydrogen and air by the humidifier 10 of humidifying; Air flow control valve 16; Thereby the cooling medium pump 21 of running circulating coolant between heat exchanger 8 or coolant cools unit and fuel battery 3; Make coolant flow path change to the triple valve 22 of heat exchanger 8 or coolant cools unit 9; Anode exhaust is discharged to the anode off-gas discharge valve (cleaning unit) 27 of outside from anode exhaust recirculation unit 6; Temperature Detector 29a to 29g; Pressure detector 30a to 30d;

Moisture detector

31a and 31b; Mass air flow sensor 32; Hydrogen flowmeter 33; Detect the voltage detection unit 36 of fuel battery 3 cell voltages; And the system controller (system control unit) 37 of controlling whole fuel cell system.

In the following description, 6 interim discharging anode exhaust are called term to the stage the combustion chamber 7 and " clean (purging) " from anode exhaust recirculation unit with cathode exhaust gas.

Combustion chamber 7 is formed the blender 23 of mixed uniformly gas and is carried combustion catalyst by anode exhaust and the air or the cathode exhaust gas of mixing hydrogen or supply, and the combustion chamber 24 of combustion mixture body constitutes.

That be arranged in combustion chamber 24 is Temperature Detector 29e, and the information of gained detected temperatures is transported to system controller 37 by the holding wire of not expressing.

Combustion chamber 7 is by anode off-gas discharge valve 27 supply of hydrogen, by air flow control valve 16 from the air supply unit 2 supply air, and by cathode exhaust gas exhaust manifolds 15 supply cathode exhaust gas.These gases mix in blender 23, and the gas of mixing burns with combustion catalyst 24.During fuel cell start-up, the burning gases that come from combustion chamber 7 are used to carry out heat exchange with cooling agent in coolant heat exchanger 8, thereby the rising coolant temperature is to operating temperature.Subsequently, by exhaust manifolds 19 exhaust of gained is discharged to the outside of system.In addition, reclaim condensed water from exhaust manifolds 19, and stock in pure water jar 25.

The pure water of stocking in pure water jar 25 uses pure water pump 35 to be fed in the humidifier 10 by pure water conduit 26.Humidifier 10 uses these pure water to come humidifying to be fed to hydrogen and air in the fuel battery 3.

The temperature of fuel battery 3 is by the cooling agent control such as antifreeze mixture, so that operating temperature is maintained under the suitable temperature.Therefore, in normal manipulation mode, triple valve 22 makes cooling medium pump 21 and 9 intercommunications of coolant cools unit, thereby makes cooling agent by airtight circuit cycle, and closed loop is made up of cooling medium pump 21, triple valve 22, coolant cools unit 9, fuel battery 3 and cooling medium pump 21.This heat accumulation with regard to permission 9 fuel battery 3 that discharge from the coolant cools unit passes to the outside of system, thereby the temperature of fuel battery 3 is maintained under the suitable temperature.

Simultaneously, during fuel cell start-up, triple valve 22 makes cooling medium pump 21 and coolant heat exchanger 8 intercommunications, thereby cooling agent is circulated by the closed loop of being made up of cooling medium pump 21, triple valve 22, coolant heat exchanger 8, fuel battery 3 and cooling medium pump 21.This raises the coolant temperature in the coolant heat exchanger 8, thereby the temperature of fuel battery 3 is increased to be suitable for the temperature that begins to operate.

System controller 37 is used action control system, prevents when anode exhaust is discharged in the combustion chamber 7 by anode off-gas discharge valve 27, and the ignition temperature of combustion chamber 7 surpasses the system control unit to fixed temperature.

In addition, system controller 37 and mass air flow sensor 32, hydrogen flowmeter 33, Temperature Detector 29a to 29g, pressure detector 30a to 30d, moisture detector 31a to 31b, and voltage detector unit 36 links to each other.Therefore, from these unit, system controller 37 can use flow velocity, the temperature and pressure from air supply unit 2 air supplied respectively, flow velocity, the temperature and pressure of the hydrogen of 1 supply from the hydrogen supply unit, temperature, pressure and the humidity of the cathode exhaust gas of discharging from negative electrode 5, and temperature, pressure and the humidity of the anode exhaust of discharging from anode 5.

In addition, electric chair detector cell 36 detects the voltage of each element cell that forms fuel battery 3 or the voltage of each combination, and each combination is formed by a plurality of element cells, and the magnitude of voltage of gained is output in the system controller 37.

System controller 37 uses detection signal and the electric energy carried from top unit to produce the load command signal.By using these signals, system controller 37 control hydrogen supply unit 1, air supply unit 2, anode exhaust recirculation unit 6, cooling medium pump 21, pure water pump 35, air flow control valve 16, triple valve 22 and anode off-gas discharge valve 27, thereby control is fed to the hydrogen of fuel battery 3 and the flow velocity of air, and the temperature of fuel battery 3.In addition, system controller 37 is implemented control, and when consequently allowing anode exhaust to be discharged in the combustion chamber 7 by anode off-gas discharge valve 27, the ignition temperature of combustion chamber 7 is no more than to fixed temperature.In addition, although do not plan special restriction, in the embodiment of current filing, system controller 37 is made up of the microcomputer that comprises CPU, memory and I/O interface.

Now, the basic order of fuel cell system operation is described as follows.Anode 4 and negative electrode 5 are respectively from hydrogen supply unit 1 and air supply unit 2 supply of hydrogen and air.Then, in reaction, produce electric energy by hydrogen in the fuel battery 3 and air.In this operating period, discharge respectively and consumed part oxygen on the residual anode exhaust that is not consumed in the anode 4, the negative electrode 5 and comprised the cathode exhaust gas that comes from the moisture that electric energy produces.

During normal running, all anode exhaust are recycled to hydrogen supply conduit 11 by anode exhaust recirculation unit 6 through anode exhaust recycling pipe 12.Then, all anode exhaust are fed to anode 4 once more.

Cathode exhaust gas is supplied in the combustion chamber 7, after this, is discharged to the outside of system by coolant heat exchanger 8 and exhaust manifolds 19.

At this moment, detect the voltage that is lower than given magnitude of voltage if detect the voltage detector unit 36 of fuel battery 3 cell voltages, the purge signal that response is sent from system controller 37 is discharged anode exhaust with given flow velocity to combustion chamber 7 from anode off-gas discharge valve 27.Simultaneously, the hydrogen flow rate of 1 supply is increased and the identical flow velocity of anode exhaust flow velocity that discharges basically from the hydrogen supply unit, keeps the pressure of supply of hydrogen constant simultaneously.

In this operating period, according to mass air flow sensor 32 detected air velocitys, hydrogen flowmeter 33 detected hydrogen flow rates, the detected cathode exhaust gas temperature of Temperature Detector 29c, the detected cathode exhaust gas pressure of pressure detector 30a, and the detected cathode exhaust gas humidity of moisture detector 31a, calculate the gas composition of cathode exhaust gas, even comprise steam, and the enthalpy of cathode exhaust gas.

Simultaneously, the composition of supposing the anode exhaust that gives off from anode exhaust recirculation unit 6 only is made up of hydrogen.Under this assumption, according to predetermined anode exhaust gas discharge speed and the detected anode exhaust temperature of Temperature Detector 29d, calculate the anode exhaust enthalpy.

According to the cathode exhaust gas and the anode exhaust enthalpy that calculate, calculate the predetermined value of ignition temperature in the combustion chamber 7.An example of computational methods is represented below.

The enthalpy of 1 mole of every kind of gas component (unit: KJ/mol) as absolute temperature T (unit: function K) is with following formulate:

Hydrogen: Hh2 (T)=-8.64597E+00+2.90620E-02 * T-4.10000E-07 * T^2+6.63433E-10 * T^3 ... (1)

Oxygen: Ho2 (T)=-8.18267E+2.55940E-02 * T+6.62550E-06 * T^2-1.40167E-09 * T^3 ... (2)

Nitrogen: Hn2 (T)=-8.31059E+2.70160E-02 * T+2.90600E-06 * T^2-9.63333E-11 * T^3 ... (3)

Water: Hh2o (T))=-2.51277E+3.02040E-02 * T+4.96650E-06 * T^2-3.72333E-09 * T^3 ... (4)

Herein, we are defined as QCo2 (mol/sec) and QCn2 (mol/sec) respectively with the oxygen gas flow rate and the nitrogen flow rate that propose that comprises in the cathode exhaust gas from the air velocity Qsa (mol/sec) that is supplied to fuel battery 3 and hydrogen flow rate Qsh (mol/sec), will be based on passing through moisture detector 29c, pressure detector 30c and moisture detector 31a be the temperature T c (K) of detected cathode exhaust gas respectively, pressure P c (KPa) and relative humidity Huc (%) and the steam flow rate that obtains is defined as QCh2o (mol/sec), to be defined as QAh2 (mol/sec) by the anode exhaust flow velocity that the opening degree of anode off-gas discharge valve 27 is determined, and the temperature of anode exhaust will be defined as Ta (K).

Under these definition, the composition of supposing air is by oxygen: nitrogen=provide at 0.21: 0.79, and oxygen and nitrogen flow rate QCo2 and QCn2, and the flow velocity QCh2o of steam is expressed as follows:

QCo2＝0.21×Qsa-Qsh/2，…(5)

QCn2＝0.79×Qsa，…(6)

QCh2o＝(QCo2+QCn2)×(Huh2o(Tc)×Huc/100)/(Pc-Huh2o(Tc)×Huc/100)，…(7)

Herein, Huh2o (Tc) is the saturated vapor pressure (KPa) under the temperature T c.

Then, based on formula (1), (2), (3) and (4), the enthalpy HC of time per unit cathode exhaust gas and the enthalpy HA of time per unit anode exhaust are by following equation expression:

HC(Tc)＝Ho2(Tc)×QCo2+Hn2(Tc)×QCn2+Hh2o(Tc)×QCh2o(KJ/sec)，…(8)

HA(Ta)＝Hh2(Ta)×Qah2(KJ/sec)，…(9)

Ignition temperature when then, burning in the calculating combustion chamber 7.

Suppose hydrogen in the anode exhaust by completing combustion, can estimate the flow velocity of various components in the burning gases according to the composition and the flow velocity of cathode exhaust gas and anode exhaust, and be expressed as follows:

Oxygen gas flow rate: QEo2=QCo2-QAh2/2 (mol/sec) ... (10)

Nitrogen flow rate: QEn2=QCn2 (mol/sec) ... (11)

Steam flow rate: QEh2o=QCh2o+QAh2 (mol/sec) ... (12)

Herein, the definition ignition temperature is Te (K), according to formula (2), (3) and (4), with the enthalpy HE of following equation expression time per unit burning gases:

HE(Te)＝Ho2(Te)×QEo2+Hn2(Te)×QEn2+Hh2o(Te)×QEh2o(KJ/sec)，…(13)

In addition, the lower calorific value of supposing hydrogen is 241.8 (KJ/mol), and the reaction heat Hb of time per unit hydrogen expresses with following formula:

Hb＝241.8×QAh2(KJ/sec)，…(14)

Based on formula (8), (9), (13) and (14), in the mode that obtains following formula ignition temperature Te is restrained calculating, it is as follows to obtain ignition temperature Te:

HC(Tc)+HA(Ta)＝HE(Te)+Hb，…(15)

Initially comprise the nitrogen G﹠W that spreads by electrolytic thin-membrane although suppose anode exhaust on the area of covered cathode 5 and anode 4, density of hydrogen increases, and the concentration of impurity reduces along with the carrying out of anode exhaust cleaning.

Therefore, composition in the supposition anode exhaust only comprises hydrogen, when calculating ignition temperature, consider that following situation determines ignition temperature: the result of the anode exhaust recirculating system that the battery pack that acts as a fuel 3 inside are made up of the hydrogen path, combustion chamber 7 supply of hydrogen concentration are essentially 100% anode exhaust, and in the final stage of discharging anode exhaust, anode exhaust recirculation unit 6 and anode exhaust recycling pipe 12 are replaced fully by hydrogen.Therefore, can avoid combustion chamber 7 excessive temperature to rise.

In addition, gas composition in moment can be by measuring unit, for

example Temperature Detector

29c, 29d and

moisture detector

31a, 31b, arrest with sufficiently high response, and can realize under the supply gas flow rate conditions with good response, by obtaining the enthalpy of every kind of gas component, and even the antianode exhaust calculate ignition temperature, can carry out control.

At this moment, if as the ignition temperature predicted value of result of calculation less than the preset upper limit value, do not change flox condition.

But,, in order to make ignition temperature, increases the air capacity that is supplied to combustion chamber 7 by fuel battery 3, thereby realize control, so that ignition temperature is limited to the value that is lower than higher limit less than higher limit if the predicted value of ignition temperature surpasses higher limit.

In this case, with the recruitment of the order computation air that describes below.

At first, suppose that air velocity to be increased is Qair (mol/sec), and based on temperature T c (K), supposition increases the enthalpy Hair of the gaseous mixture between air and the steam in formula (2), (3) and (4), described enthalpy is taken from the increment of fuel battery 3.Under this hypothesis, even if because increasing to fuel battery 3 air supplied flow velocitys, and when the wettability of fuel battery 3 inside was enough simultaneously, the thermal capacitance of fuel battery 3 also was very big, so on short terms, think that the temperature T c of cathode exhaust gas and relative humidity Huc do not change.Therefore,

Hair(Tc)＝Qair×0.21×Ho2(Tc)+Qair×0.79×Hn2(Tc)+Qair×(Huh2o(Tc)×Huc/100/(Pc-Huh2o(Tc)×Huc/100))(KJ/mol)，…(16)

Then, the flow velocity increase of oxygen, nitrogen and steam equals the value that air velocity increases in the burning gases, and the following equation expression of enthalpy HE (Te) ' of the burning gases that obtain when temperature T e:

QEo2’＝QCo2-Qao2+0.21×Qair(mol/sec)，…(10)’

QEn2’＝QCn2+0.71×Qair(mol/sec)，…(11)’

QEh2o’＝QEh2o+Qair×(Huh2o(Tc)×Huc/100/(Pc-Huh2o(Tc)×Huc/100))(mol/sec)，…(12)’

HE(Te)’＝Ho2(Te)×QEo2’+Hn2(Te)×QEn2’+Hh2o(Te)×QEh2o’(KJ/sec)，…(13)’

Increase the value of Hair to the left side of equation, and when substituting ignition temperature Te with predetermined ignition temperature higher limit Tmax on the right, carry out convergence according to air velocity Qair and calculate, and the following calculating of Qair:

HC(Tc)+HA(Ta)+Hair(Tc)＝HE(Tmax)’+Hb，…(17)

When the given anode exhaust gas discharge time has disappeared, interruption is discharged anode exhaust in combustion chamber 7, interrupt simultaneously from the hydrogen supply unit 1 supply hydrogen flow rate increase and from the increase of air supply unit 2 air supplied flow velocitys, so operation is converted into normal running.

Fig. 2 A to 2E sets forth the flow chart of ignition temperature control in the first embodiment, and wherein, Fig. 2 A represents the ignition temperature Te of combustion chamber 7; Fig. 2 B represents the 2 air supplied flow velocitys from the air supply unit; Fig. 2 C represents the rate of discharge of cathode exhaust gas; Fig. 2 D represents the flow velocity of the hydrogen of hydrogen supply unit 1 supply; And Fig. 2 E represents the rate of discharge of anode exhaust.

In Fig. 2 A to 2E, because the hydrogen flow rate of 1 supply is increased and the identical flow velocity of anode exhaust flow velocity that discharges basically from the hydrogen supply unit, discharge anode exhaust simultaneously, thus before and after beginning to discharge anode exhaust a period of time at interval in, the output of fuel battery 3 remains unchanged.In addition, when the ignition temperature Te that is in prediction surpasses in the operation of higher limit Tmax of ignition temperature, shown in Fig. 2 C, because 2 air supplied flow velocitys increase from the air supply unit, and the rate of discharge of cathode exhaust gas increases, so so control makes and has avoided the ignition temperature in the combustion chamber to surpass the higher limit Tmax of ignition temperature in the actual practice.

By doing like this, produce following advantageous effect: shown in fine line among Fig. 2 A, the related art fuel cell that rises with excessive temperature is different, and the situation that ignition temperature surpasses ignition temperature higher limit Tmax can not take place, and can prevent the combustion catalyst degradation of combustion chamber.

Fig. 3 sets forth the flow chart of system controller controlled function in the first embodiment.

At first, in step (hereinafter referred " S ") 10, the cell voltage of fuel battery 3 is detected by voltage detector unit 36, and makes cell voltage whether less than the judgement of set-point.If the voltage of each element cell that voltage detector unit 36 detects or the voltage of every group of element cell drop to below the set-point, operation proceeds to S12.If these voltages surpass set-point, operation is back to S10 so, thereby repeats the detection and the judgement thereof of cell voltage.In S12, in order to predict when cleaning operation recovers cell voltage, the discharging ignition temperature that anode exhaust produced is calculated ignition temperature Te in combustion chamber 7.Formula (1) above using on the basis that the enthalpy of gas calculates in inflow or outflow combustion chamber 7, calculates the predicted value of described ignition temperature Te to (15).

In S14, judge whether ignition temperature Te surpasses the higher limit Tmax of ignition temperature.In the judgement of S14, if ignition temperature Te is no more than the higher limit Tmax of ignition temperature, operation proceeds to S40, implements to clean normally.

In the judgement of S14, surpass predetermined ignition temperature higher limit Tmax if judge ignition temperature Te, carry out S16 operation afterwards, implement to clean and control, so that increase the flow velocity of air supplied in combustion chamber 7, thereby the ignition temperature Te of prevention combustion chamber 7 surpasses the higher limit Tmax of ignition temperature.

In S16, the air velocity Qair that calculating will increase.In this computing interval, as proposing according to top formula (1) to (17), on of short duration meaning, think under situation about not changing aspect the temperature T c of cathode exhaust gas and the relative humidity Huc, to obtain the flow velocity Qair of air to be increased based on the calculating of enthalpy.

In next step S18, cleaning command is sent to air supply unit 2, anode off-gas discharge valve 27 and hydrogen supply unit 1 from system controller 37.When receiving described cleaning command, in S20, the flow velocity that air supply unit 2 increases to negative electrode 5 air supplied; In S24, anode off-gas discharge valve 27 is opened; And in S26, hydrogen supply unit 1 increases the flow velocity of the hydrogen of anode 4 supplies.

In S28 subsequently, judge from cleaning the given time interval Tp of beginning whether disappear, if do not have, operation is back to S28.If disappear from cleaning the given time interval Tp of beginning, operation proceeds to S30.In S30, interrupt the increase of the hydrogen flow rate of 1 supply, and in S32, close anode off-gas discharge valve 27 from the hydrogen supply unit, in S34, interrupt increase simultaneously from air supply unit 2 air supplied flow velocitys.This just makes fuel cell system be back to normal operating condition.

Simultaneously, in S40, under given condition, begin to discharge anode exhaust.In S42, cleaning command is sent to anode off-gas discharge valve 27 and hydrogen supply unit 1 from system controller 37.When receiving described cleaning command, in S44, open anode off-gas discharge valve 27; And in S46, hydrogen supply unit 1 increases the flow velocity of the hydrogen of anode 4 supplies.

In S48 subsequently, judge from cleaning the given time interval Tp of beginning whether disappear, if do not have, operation is back to S48.If disappear from cleaning the given time interval Tp of beginning, operation proceeds to S50.In S50, interrupt the increase of the hydrogen flow rate of 1 supply, and in S52, close anode off-gas discharge valve 27 from the hydrogen supply unit.This just makes fuel cell system be back to normal operating condition.

In the above in the embodiment of the current filing of Ti Chuing, when discharging anode exhaust from anode exhaust recirculation unit by control, the temperature of burning gases described in the combustion chamber never surpasses to fixed temperature, can have can suppress the combustion chamber because excessive heat load and the advantageous effect of performance reduction.

In addition, because the service load of fuel cell stack, can predict the flow velocity of the mist that enters the combustion chamber and form at least a, thereby tentative prediction ignition temperature, so can control system, so that may surpass under the situation to fixed temperature in ignition temperature, the prevention ignition temperature surpasses to fixed temperature, thereby, even if because burning is only finished at short notice, entry of combustion chamber temperature and combustor exit temperature there are differences, and have also limited the excessive rising of combustion chamber bulk temperature, thereby have suppressed because the reduction of the chamber performance that the excessive heat load causes.

(second embodiment)

Next, consult Fig. 4 to 6, describe second embodiment in detail according to fuel cell system of the present invention.

Fig. 4 is the system construction drawing of setting forth the second embodiment structure.In second embodiment, make up fuel cell system, so that between air supply unit 2 and combustion chamber 7, settle air flows control valve 17 and air supply conduit 18 in addition, make the portion of air of 2 supplies be shunted and directly be supplied to combustion chamber 7 from the air supply unit.Second embodiment is similar to first embodiment shown in Figure 1 on other structure, so in order to omit repeat specification, the components identical with first embodiment represented with identical label.

In above-mentioned this structure, the embodiment of current filing can directly be supplied air from air supply unit 2 to combustion chamber 7 by air flows control valve 17, and can not disturb fuel battery 3, the result has improved for the quick response that increases air supplied flow velocity in combustion chamber 7, thereby has limited the rising of ignition temperature more accurately.

In this case, except using the temperature T air (K) that detects by the Temperature Detector 29a that detects 2 air supplied temperature to replace Tc (k) to be used as the air themperature that will increase from the air supply unit, and because the air that will increase directly is supplied to combustion chamber 7, and do not disturb beyond the fuel battery 3, according to first embodiment in identical mode, do not consider to follow the steam flow rate that will increase of air increase, carry out the order that increases air velocity.

In this operation, replace formula (16) and (13) ', with following formula substitution formula (17), calculate the recruitment of air velocity.

Hair(Tair)＝Qair×0.21×Ho2(Tair)+Qair×0.79×Hn2(Tair)(KJ/mol)，…(16)’

HE(Te)’＝Ho2(Te)×QEo2’+Hn2(Te)×QEn2’+Hh2o(Te)×QEh2o(KJ/sec)，…(13)

Fig. 5 A to 5E is the flow chart that is set forth in ignition temperature control in second embodiment, and wherein, Fig. 5 A represents the ignition temperature Te of combustion chamber 7; Fig. 5 B represents the flow velocity of air supply unit 2 air supplied; Fig. 5 C represents the rate of discharge of cathode exhaust gas; Fig. 5 D represents the flow velocity of the hydrogen of hydrogen supply unit 1 supply; And Fig. 5 E represents the rate of discharge of anode exhaust.

In Fig. 5 A to 5E, because anode exhaust one discharging, the hydrogen flow rate of 1 supply is just increased the identical flow velocity of anode exhaust flow velocity with discharging basically from the hydrogen supply unit, so before and after beginning to discharge anode exhaust in a period of time interval, the output of fuel battery 3 remains unchanged.In addition, because when the ignition temperature Te of prediction surpasses the higher limit Tmax of ignition temperature, by air flows control valve 17, from the flow velocity increase of air supply unit 2 air supplied, so so control makes actual combustion temperature in the combustion chamber be no more than the higher limit Tmax of ignition temperature.When this thing happens,,, remain on certain fixed value so shown in Fig. 5 C, the mass rate of emission of cathode exhaust gas does not change because the flow path that air flows approach that will increase and cathode exhaust gas flow is irrelevant.

By doing like this, produce following advantageous effect: shown in fine line among Fig. 5 A, the related art fuel cell that rises with excessive temperature is different, and the situation that ignition temperature surpasses ignition temperature higher limit Tmax can not take place, and can prevent the combustion catalyst degradation of combustion chamber.

Fig. 6 is the flow chart that is set forth in system controller controlled function in second embodiment.

At first, in S10, the cell voltage of fuel battery 3 is detected by voltage detector unit 36, and makes cell voltage whether less than the judgement of set-point.If the voltage of each element cell that voltage detector unit 36 detects or the voltage of every group of element cell drop to below the set-point, operation proceeds to S12.If these voltages surpass set-point, operation is back to S10 so, thereby repeats the detection and the judgement thereof of cell voltage.In S12, in order to predict when cleaning operation recovers cell voltage, the discharging ignition temperature that anode exhaust produced is calculated ignition temperature Te in combustion chamber 7.Formula (1) above using on the basis that the enthalpy of gas calculates in inflow or outflow combustion chamber 7, calculates the predicted value of described ignition temperature Te to (15).

In S14, judge whether ignition temperature Te surpasses the higher limit Tmax of predetermined combustion temperature.In the judgement of S14, if ignition temperature Te is no more than the higher limit Tmax of ignition temperature, operation proceeds to S40, implements to clean normally.

In next step S18, cleaning command is sent to air supply unit 2 from system controller 37; Flow control valve 16,17; Anode off-gas discharge valve 27 and hydrogen supply unit 1.When receiving described cleaning command, in S20, the flow velocity that air supply unit 2 increases to negative electrode 5 air supplied; In S21, open air velocity control valve 16, to negative electrode 5 supply air, open air velocity control valve 17 simultaneously, directly supply air by this valve from air supply unit 2 to combustion chamber 7.In S24, open anode off-gas discharge valve 27; And in S26, hydrogen supply unit 1 increases the flow velocity of the hydrogen of anode 4 supplies.

In S28 subsequently, judge from cleaning the given time interval Tp of beginning whether disappear, if do not have, operation is back to S28.If disappear from cleaning the given time interval Tp of beginning, operation proceeds to S30.In S30, interrupt the increase of the hydrogen flow rate of 1 supply from the hydrogen supply unit, in S32, close anode off-gas discharge valve 27.In S33, recover the opening degree of air velocity control valve 16, close air velocity control valve 17 simultaneously.In S34, executable operations is to interrupt the increase from air supply unit 2 air supplied flow velocitys.This just makes fuel cell system be back to normal operating condition.

Simultaneously, the normal wash of carrying out in S40 to S52 is identical with the content of consulting the description of first embodiment, has therefore omitted repeat specification.

In the above in second embodiment of Ti Chuing, when discharging anode exhaust from anode exhaust recirculation unit by control, the temperature of burning gases described in the combustion chamber never surpasses to fixed temperature, can have can suppress the combustion chamber because excessive heat load and the advantageous effect of performance reduction.

In addition, because the service load of fuel cell stack, can predict the flow velocity of the mist that enters the combustion chamber and form at least a, thereby tentative prediction ignition temperature, so can control system, so that may surpass under the situation to fixed temperature in ignition temperature, the prevention ignition temperature surpasses to fixed temperature, thereby, even if make entry of combustion chamber temperature and combustor exit temperature there are differences because burning is only finished at short notice, also limited the excessive rising of combustion chamber bulk temperature, thereby suppressed because the reduction of the chamber performance that the excessive heat load causes.

In addition, has another favourable effect: when when anode exhaust recirculation unit discharges anode exhaust temporarily, implement control, make rate of discharge increase to the oxidant gas feeding unit of fuel battery supply oxidant gas, force a part of oxidant gas directly to be supplied to the combustion chamber, thereby suppress the excessive rising of ignition temperature; Thereby simplified the control of system, and can suppress because the reduction of the chamber performance that the excessive heat load causes.

(the 3rd embodiment)

Next, consult Fig. 7 to 9, describe the 3rd embodiment in detail according to fuel cell system of the present invention.

Fig. 7 is the system construction drawing of setting forth the 3rd embodiment structure.The assembly in first embodiment shown in Figure 1, the 3rd embodiment is planned further to comprise specific auxiliary air 28 of supplying auxiliary airs for combustion chamber 7, is measured the auxiliary air flow meter 38 of auxiliary air flow velocity, and detects from the Temperature Detector 29h of the auxiliary air temperature of auxiliary air 28 supplies.The 3rd embodiment is similar to first embodiment shown in Figure 1 on other structure, so in order to omit repeat specification, the components identical with first embodiment represented with identical label.

Compare with second embodiment with first embodiment,, make the air that during cleaning, will increase only by combustion chamber 7 and coolant heat exchanger 8, and be discharged to the outside, so flow resistance is minimized because dispose the 3rd embodiment.This has reduced from the pressure of the auxiliary air of auxiliary air 28 supplies, pressure ratio in the auxiliary air 28 is lowered, thereby suppressed the increase of power consumption, the while can be controlled and not change the conditions of air that is supplied to fuel battery 3.

In this case, suppose that the Qair in the 3rd embodiment is the flow velocity that is supplied to the auxiliary air of combustion chamber 7 from auxiliary air 28, and the detected temperature of temperature T air representation temperature detector 29h, auxiliary air require flow velocity according to second embodiment in identical mode calculate.

Fig. 8 A to 8E is the flow chart that is set forth in ignition temperature control in the 3rd embodiment, and wherein, Fig. 8 A represents the ignition temperature Te of combustion chamber 7; Fig. 8 B represents the air velocity of the auxiliary air of auxiliary air 28 supplies; Fig. 8 C represents the rate of discharge of cathode exhaust gas; Fig. 8 D represents the flow velocity of the hydrogen of hydrogen supply unit 1 supply; And Fig. 8 E represents the rate of discharge of anode exhaust.

In Fig. 8 A to 8E, because anode exhaust one discharging, the hydrogen flow rate of 1 supply is just increased the identical flow velocity of anode exhaust flow velocity with discharging basically from the hydrogen supply unit, so before and after beginning to discharge anode exhaust in a period of time interval, the output of fuel battery 3 remains unchanged.In addition, when the ignition temperature Te of prediction surpasses the higher limit Tmax of ignition temperature, shown in Fig. 8 B, because air also is fed to the combustion chamber 7 from auxiliary air 28, so so control makes actual combustion temperature in the combustion chamber be no more than the higher limit Tmax of ignition temperature.

By doing like this, produce following advantageous effect: shown in fine line among Fig. 8 A, the related art fuel cell that rises with excessive temperature is different, and the situation that ignition temperature surpasses ignition temperature higher limit Tmax can not take place, and can prevent the combustion catalyst degradation of combustion chamber.

Fig. 9 is the flow chart that is set forth in system controller controlled function in the 3rd embodiment.

In next step S18, cleaning command is sent to auxiliary air 28, anode off-gas discharge valve 27 and hydrogen supply unit 1 from system controller 37.When receiving described cleaning command, in S23, auxiliary air 28 is supplied auxiliary airs to combustion chamber 7, and in S24, opens anode off-gas discharge valve 27; And in S26, hydrogen supply unit 1 increases the flow velocity of the hydrogen of anode 4 supplies.

In S28 subsequently, judge from cleaning the given time interval Tp of beginning whether disappear, if do not have, operation is back to S28.If disappear from cleaning the given time interval Tp of beginning, operation proceeds to S30.In S30, interrupt the increase of the hydrogen flow rate of 1 supply from the hydrogen supply unit, in S32, close anode off-gas discharge valve 27, and interrupt the operation of auxiliary air 28.This just makes fuel cell system be back to normal operating condition.

In the above in the 3rd embodiment of Ti Chuing, when anode exhaust recirculation unit discharges anode exhaust temporarily, control never surpasses to provide to fixed temperature from the temperature of the described burning gases of combustion chamber and can suppress the combustion chamber because excessive heat load and advantageous effect that performance reduces.

(the 4th embodiment)

Next, consult Figure 10 A to 10E and Figure 11, describe the 4th embodiment of the present invention.The 4th embodiment has the structure identical with first embodiment shown in Figure 1.The 4th embodiment has following feature: if wherein judge the higher limit that the ignition temperature of prediction surpasses ignition temperature, the flow velocity that makes anode exhaust is less than predetermined rate of discharge, and prolong the time of anode exhaust gas discharge, thereby reduce the ignition temperature of combustion chamber.

Therefore, the 4th embodiment is implemented control, so that before calculating ignition temperature Te, carry out the calculating identical with first embodiment, if thereby the ignition temperature Te that judges calculating surpasses the higher limit Tmax of ignition temperature, do not change the flow velocity of cathode exhaust gas, and the rate of discharge that makes anode exhaust is less than predetermined flow velocity, and anode exhaust is discharged the time interval longer than predetermined drain time interval (Tp) (Tp ").

Figure 10 A to 10E is the time diagram that is set forth in ignition temperature control in the 4th embodiment, and wherein, Figure 10 A represents the ignition temperature Te of combustion chamber 7; Figure 10 B represents the rate of discharge of cathode exhaust gas; Figure 10 C represents the flow velocity of the hydrogen of hydrogen supply unit 1 supply; And Figure 10 D represents the rate of discharge of anode exhaust.

When the ignition temperature Te of prediction surpasses the higher limit Tmax of ignition temperature, shown in Figure 10 D, the rate of discharge that makes anode exhaust less than normal wash during the flow velocity of anode exhaust, and anode exhaust is discharged the longer time (Tp ") at interval.This has reduced the combustion heat value that time per unit produces, and causes the reduction of ignition temperature.

Produce following advantageous effect: shown in fine line among Figure 10 A, the related art fuel cell that rises with excessive temperature is different, the situation that ignition temperature surpasses ignition temperature higher limit Tmax can not take place, and can prevent the combustion catalyst degradation of combustion chamber.

In addition, when using high-pressure bottle, high pressure hydrogen tank for example, during as hydrogen supply unit 1, meet the hydrogen flow rate of only regulating supply by the opening degree of regulating anode off-gas discharge valve because use, so can avoid because when increasing air velocity air supply unit 2 that needs in first to the 3rd embodiment structure and auxiliary air 28 and the increase of the power consumption that causes.

The drain time that anode exhaust is predetermined is defined as Tp (second) at interval, and the drain time of anode exhaust is defined as Tp at interval after will changing ", the Rd that advances the speed of anode exhaust flow velocity is defined as follows:

Rd＝Tp”/Tp，…(18)

Anode exhaust flow velocity QAh2o when then, reducing rate of discharge " be expressed as follows:

QAh2o”＝QAh2×Rd，…(19)

From these equatioies, formula (9), (10), (12), (13), (15) can be rewritten as:

HA(Ta)”＝Hh2(Ta)×QAh2”，(KJ/sec)…(9)”

QEo2”＝QCo2-QAh2”/2，(mol/sec)…(10)”

QEh2o”＝QCh2o+QAh2”，(mol/sec)…(12)”

HE(Te)”＝Ho2(Te)×QEo2”+Hn2(Te)×QEn2+Hh2o(Te)×QEh2o”(KJ/sec)，…(13)”

HC(Tc)+HA(Ta)”＝HE(Te)”+ΔHb，…(15)”

Then, superincumbent equation (15) " in, replace ignition temperature Te with higher limit Tmax, calculate with regard to the Rd do convergence of advancing the speed of anode exhaust gas discharge speed, thereby calculate Rd.

The Rd that substitution provides from top equation (18) obtains the drain time interval T p of anode exhaust ".

In addition, take in the situation of the fixed throttle port form in aperture for example, can use hydrogen supply unit 1 to reduce hydrogen supply pressure as a kind of technology that reduces hydrogen flow rate in anode off-gas discharge valve 27.

Figure 11 is the flow chart that is set forth in system controller controlled function in the 4th embodiment.

At first, in S10, the cell voltage of fuel battery 3 is detected by voltage detector unit 36, and makes cell voltage whether less than the judgement of set-point.If the voltage of each element cell that voltage detector unit 36 detects or the voltage of every group of element cell drop to below the set-point, operation proceeds to S12.If these voltages surpass set-point, operation is back to S10 so, thereby repeats the detection and the judgement thereof of cell voltage.In S12, in order to predict the recovery of using cleaning operation to realize cell voltage, the ignition temperature that causes is calculated ignition temperature Te thereby anode exhaust is discharged in the combustion chamber 7.Formula (1) above using on the basis that the enthalpy of gas calculates in inflow or outflow combustion chamber 7, calculates the predicted value of described ignition temperature Te to (15).

In the judgement of S14, surpass predetermined ignition temperature higher limit Tmax if judge ignition temperature Te, carry out S15 operation afterwards, under following control, carry out and clean: reduce the anode exhaust flow velocity that is supplied to combustion chamber 7 from anode off-gas discharge valve 27, prolong the time interval of anode exhaust gas discharge simultaneously, thereby the ignition temperature Te of prevention combustion chamber 7 surpasses the higher limit Tmax of ignition temperature.

In S15, calculate the minimizing speed Rd of anode exhaust flow velocity.In continuous S17, calculate the drain time interval T p of anode exhaust " and rate of discharge QAh2 ".When calculating these factors, based on top formula (18), (19) and (9) " to (15) " form as discussed above the calculating of enthalpy calculate.

In next step S18, cleaning command is sent to anode off-gas discharge valve 27 and hydrogen supply unit 1 from system controller 37.When receiving described cleaning command, in S24, open anode off-gas discharge valve 27; And in S26, hydrogen supply unit 1 increases the flow velocity of the hydrogen of anode 4 supplies.

In S28 subsequently, judge from cleaning the given time interval Tp of beginning " whether disappear, if do not have, operation is back to S28.If from cleaning the given time interval Tp of beginning " disappear, operation proceeds to S30.In S30, interrupt the increase of the hydrogen flow rate of 1 supply from the hydrogen supply unit, in S32, close anode off-gas discharge valve 27.This just makes fuel cell system be back to normal operating condition.

In the above in the 4th embodiment of Ti Chuing, has following advantageous effect: forcing anode exhaust when anode exhaust recirculation unit discharges temporarily, make the anode exhaust flow velocity that is supplied to combustion chamber 7 less than predetermined rate of discharge, and control anode exhaust, so that the time that discharging prolongs, thereby suppress the excessive rising of ignition temperature, thereby in configuration, simplified the structure of system, and suppressed the performance reduction of combustion chamber.

(the 5th embodiment)

Next, consult Figure 12 A to 12E and Figure 13, describe the 5th embodiment of the present invention.The 5th embodiment has the structure identical with first embodiment shown in Figure 1.The 5th embodiment has following feature: if wherein judge the higher limit that the ignition temperature of prediction surpasses ignition temperature, the discharge mode of anode exhaust is changed into discontinuous discharge mode.That is to say, make the time interval of anode exhaust discharging in circulation once be shorter than given drain time at interval, and anode exhaust is repeated discharging repeatedly, thereby reduce the ignition temperature of combustion chamber.

Therefore, the 5th embodiment is implemented control, so that when calculating ignition temperature Te, carry out the calculating identical with first embodiment, if thereby the ignition temperature Te that judges calculating surpasses the higher limit Tmax of ignition temperature, do not change the flow velocity of cathode exhaust gas and the rate of discharge of anode exhaust, and make the time interval of anode exhaust discharging in circulation once be shorter than given drain time at interval, and in the longer at interval time, repeatedly discharging anode exhaust than given drain time.This makes the discharge mode of anode exhaust be set at the time interval of predetermined optional anode exhaust gas discharge once more, thereby anode exhaust is discharged in the circulation that disperses, thereby during anode exhaust gas discharge, the ignition temperature of combustion chamber is suppressed to the value that is lower than higher limit.

By operating condition, determine drain time Tp to each prediction preliminary and experimentally " (second) drain time interval T r " (second) and discharging number of times X (inferior) control the drain time method at interval of setting.

Figure 12 A to 12E is the flow chart that is set forth in ignition temperature control in the 5th embodiment, and wherein, Figure 12 A represents the ignition temperature Te of combustion chamber 7; Figure 12 B represents the flow velocity of air supply unit 2 air supplied; Figure 12 C represents the rate of discharge of cathode exhaust gas; Figure 12 D represents the flow velocity of the hydrogen of hydrogen supply unit 1 supply; And Figure 12 E represents the rate of discharge of anode exhaust.

In Figure 12 A to 12E, repeatedly carry out repetitive operation, make anode exhaust be discharged time interval Tp , and will discharge interval T r break period.To be discharged time interval Tp synchronous with anode exhaust, and the hydrogen flow rate of 1 supply is increased the speed that equals anode exhaust gas discharge speed from the hydrogen supply unit.When carrying out the anode exhaust gas discharge operation in this discontinuous mode, chamber temperature Te takes the sawtooth waveform shown in Figure 12 A, and carries out control, so that the peak value of sawtooth waveform is no more than the higher limit Tmax of ignition temperature.

By doing like this, produce following advantageous effect: shown in fine line among Figure 12 A, the related art fuel cell that rises with excessive temperature is different, and the situation that ignition temperature surpasses ignition temperature higher limit Tmax can not take place, and can prevent the combustion catalyst degradation of combustion chamber.

Figure 13 is the flow chart that is set forth in system controller controlled function in the 5th embodiment.

At first, in S10, the cell voltage of fuel battery 3 is detected by voltage detector unit 36, and makes cell voltage whether less than the judgement of set-point.If the voltage of each element cell that voltage detector unit 36 detects or the voltage of every group of element cell drop to below the set-point, operation proceeds to S12.If these voltages surpass set-point, operation is back to S10 so, thereby repeats the detection and the judgement thereof of cell voltage.In S12, use cleaning operation to recover cell voltage, thereby the discharging ignition temperature that anode exhaust produced in the pre-direction finding combustion chamber 7 is calculated ignition temperature Te like this.Formula (1) above using on the basis that the enthalpy of gas calculates in inflow or outflow combustion chamber 7, calculates the predicted value of described ignition temperature Te to (15).

In the judgement of S14, surpass predetermined ignition temperature higher limit Tmax if judge ignition temperature Te, by the operation after the S60, anode exhaust is discharged in discontinuous mode, thereby cleans under the control below: the ignition temperature Te of control combustion chamber 7 is no more than the higher limit Tmax of ignition temperature.In S60, calculate the Rg that advances the speed of cathode exhaust gas flow velocity.In S62, as the conditions of discharge of anode exhaust, executable operations is set drain time Tp , the drain time interval T r of once circulation and is discharged number of times X.

In next step S64, cleaning command is sent to anode off-gas discharge valve 27 and hydrogen supply unit 1 from system controller 37.When receiving described cleaning command, in S66, open anode off-gas discharge valve 27; And in S68, hydrogen supply unit 1 increases the flow velocity of the hydrogen of anode 4 supplies.

In S70 subsequently, judge whether given time interval Tp disappears from cleaning, if do not have, operation is back to S70.If from cleaning, given time interval Tp disappears, operation proceeds to S72.In S72, interrupt the increase of the hydrogen flow rate of 1 supply from the hydrogen supply unit, in S74, close anode off-gas discharge valve 27.In S76, judge whether given time interval Tr disappears, if do not have, operation is back to S76.If given time interval Tr disappears, operation proceeds to S78, wherein, judges whether the discharging number of times has reached the value of X.If the discharging number of times does not reach the value of X, operation is back to S66.If the discharging number of times has reached the value of X, interrupt batch cleaning, and return.This makes fuel cell system return to normal operating condition.

In the above in the 5th embodiment of Ti Chuing, forcing anode exhaust when anode exhaust recirculation unit discharges temporarily, implement control, the flow velocity of cathode exhaust gas and anode exhaust is not changed, and make the time interval of anode exhaust discharging in once circulating be shorter than given rate of discharge, force anode exhaust to be discharged discontinuously repeatedly simultaneously; Therefore, has following advantageous effect:, reduced the average ignition temperature between draining period by implement the discharging of anode exhaust in the mode of separating.

(the 6th embodiment)

Next, consult Figure 14,15A to 15E and Figure 16, describe the 6th embodiment in detail according to fuel cell system of the present invention.Figure 14 is the system construction drawing of setting forth the 6th embodiment structure.The assembly in first embodiment shown in Figure 1, the 6th embodiment plans further to comprise the blender 23 inner feed water valves 34 that inject water to combustion chamber 7, and detects from the Temperature Detector 29j of pure water pump 35 to the water temperature of feed water valve 34 supplies.The 6th embodiment is similar to first embodiment shown in Figure 1 on other structure, so in order to omit repeat specification, the components identical with first embodiment represented with identical label.

In the 6th embodiment, surpass higher limit if judge the ignition temperature of calculating, supply pure water from feed water valve 34 to combustion chamber 7 with suitable flow velocity, thereby responsively suppress the excessive rising of ignition temperature fast.

In this operation, to the flow velocity of the water of combustion chamber supply by the order computation of describing below.

Definition is Tw (K) by the detected water temperature of Temperature Detector 29j, and the enthalpy Hw (KJ/mol) of per 1 mole of aqueous water calculates according to following formula:

Water (liquid state): Hw (Tw)=-3.07835e+02+7.25025e-02 * Tw+4.38217e-06 * Tw^2 ... (20)

The flow velocity of the water of definition supply is Qw (mol/sec), so the enthalpy (Hsw (Tw)) of the water of supply is provided by following formula:

Hsw(Tw)＝Hw(Tw)×Qw(KJ/mol)，…(21)

Therefore, formula (12) and (13) are rewritten as:

QEh2o””＝QCh2o+QAh2+Qw(mol/sec)，…(12)””

HE(Te)””＝Ho2(Te)×QEo2+Hn2(Te)×QEn2+Hh2o(Te)×QEh2o””(KJ/sec)，…(13)””

According to equation (15), the water yield Qw that just replenishes the supply restrains calculating, under the situation of ignition temperature Te=higher limit Tmax, and formula below setting up, thus calculate Qw:

HC(Tc)+HA(Ta)+Hw(Tw)＝HE(Tmax)+Hb，…(22)

Figure 15 A to 15E is the flow chart that is set forth in ignition temperature control in the 6th embodiment, and wherein, Figure 15 A represents the ignition temperature Te of combustion chamber 7; Figure 15 B represents from the flow velocity of feed water valve 34 to the water of combustion chamber 7 supplies; Figure 15 C represents the rate of discharge of cathode exhaust gas; Figure 15 D represents the flow velocity of the hydrogen of hydrogen supply unit 1 supply; And Figure 15 E represents the rate of discharge of anode exhaust.

When the ignition temperature Te of prediction surpasses the higher limit Tmax of ignition temperature,, supply pure water to combustion chamber 7 from feed water valve 34 according to the drain time Tp of discharging anode exhaust.As the result of rapid evaporation, be supplied to the water of combustion chamber 7 to draw heat of evaporation from environment, cause the ignition temperature of combustion chamber 7 to reduce.

According to described embodiment, has following favourable effect: can avoid temperature shown in fine line among Figure 15 A to rise to ignition temperature, and can prevent the combustion catalyst degradation of combustion chamber above ignition temperature higher limit Tmax.Temperature rises to ignition temperature, as figure

Figure 16 is the flow chart that is set forth in system controller controlled function in the 6th embodiment.

At first, in S10, the cell voltage of fuel battery 3 is detected by voltage detector unit 36, and makes cell voltage whether less than the judgement of set-point.If the voltage of each element cell that voltage detector unit 36 detects or the voltage of every group of element cell drop to below the set-point, operation proceeds to S12.If these voltages surpass set-point, operation is back to S10 so, thereby repeats the detection and the judgement thereof of cell voltage.In S12, use cleaning operation to realize the recovery of cell voltage, the ignition temperature that causes is calculated ignition temperature Te thus thereby the prediction anode exhaust is discharged in the combustion chamber 7.Formula (1) above using on the basis that the enthalpy of gas calculates in inflow or outflow combustion chamber 7, calculates the predicted value of described ignition temperature Te to (15).

In the judgement of S14, surpass predetermined ignition temperature higher limit Tmax if judge ignition temperature Te, carry out S80 operation afterwards, implement to clean, carry out temperature control simultaneously, so that to combustion chamber 7 supply water, thereby the ignition temperature Te of prevention combustion chamber 7 surpasses the higher limit Tmax of ignition temperature.

In S80, calculate from the flow velocity Qw of feed water valve 34 to the water of combustion chamber 7 supplies.In this calculated, to (22), the enthalpy that calculates on the basis based on the water temperature T w that detects at Temperature Detector 29j obtained the flow velocity Qw of the water of supply according to above-mentioned formula (20).

In next step S82, cleaning command is sent to feed water valve 34, anode off-gas discharge valve 27 and hydrogen supply unit 1 from system controller 37.When receiving described cleaning command, in S23, air are supplied to combustion chamber 7 in air supply unit 2, and in S84, begin to supply water from feed water valve 34 to combustion chamber 7, and in S86, open anode off-gas discharge valve 27; And in S88, hydrogen supply unit 1 increases the flow velocity of the hydrogen of anode 4 supplies.

In S90 subsequently, judge whether given time interval Tp disappears from cleaning, if do not have, operation is back to S90.If from cleaning, given time interval Tp disappears, operation proceeds to S92, interrupts the increase of the hydrogen flow rate of 1 supply from the hydrogen supply unit, and in S94, closes anode off-gas discharge valve 27, and in S96, interrupt from feed water valve 34 supply water.This makes fuel cell system return to normal operating condition.

In the above in the 6th embodiment of Ti Chuing, when anode exhaust recirculation unit discharges anode exhaust temporarily, owing to can suppress the excessive rising of ignition temperature to combustion chamber 7 supply water with suitable flow velocity, thereby only provide and to need change the fuel battery operating condition minimumly, just can suppress the advantageous effect of the chamber performance reduction that cause with favourable response because of the excessive heat load.

(the 7th embodiment)

Next, consult Figure 18 A to 18E and Figure 19 to 24, describe the 7th embodiment of the present invention.The 7th embodiment has the structure identical with first embodiment shown in Figure 1.In the first embodiment, in order to suppress the rising of ignition temperature, in the discharging anode exhaust simultaneously, increase the flow velocity (or flow velocity of cathode exhaust gas) of air fast.But, when increasing air velocity with this immediate mode, because actuator is for example controlled the response of the pressure-regulating valve delay of air velocity, the fluctuation of pressure may take place.In addition, according to the quantity of pressure oscillation, the membrane electrode assembly of fuel cell has the compressive strength of increase certainly, and the possibility of result increases cost.

Consider the problems referred to above, a target of the embodiment of current filing provides a kind of fuel cell system of control, suppresses the fluctuation of air pressure, even if force in fuel cell, the ignition temperature of combustion chamber also is no more than to fixed temperature, does not need concrete compressive strength simultaneously.

Figure 18 A to 18E is the flow chart that is set forth in ignition temperature control in the 7th embodiment, and wherein, Figure 18 A represents the ignition temperature Te of combustion chamber 7; Figure 18 B represents the flow velocity of air supply unit 2 air supplied; Figure 18 C represents the rate of discharge of cathode exhaust gas; Figure 18 D represents the flow velocity of the hydrogen supplied; And Figure 18 E represents the rate of discharge of anode exhaust.

Shown in Figure 18 A to 18E, because when beginning to discharge anode exhaust, the hydrogen flow rate of 1 supply just is increased the added value that equals anode exhaust gas discharge speed from the hydrogen supply unit, so before and after beginning to discharge anode exhaust a period of time at interval in, the output of fuel battery 3 remains unchanged.

In addition, carry out control, so that when the ignition temperature Te of prediction surpasses the higher limit Tmax of ignition temperature, increase from the air supply unit by 2 air supplied flow velocitys, thereby increase the rate of discharge of cathode exhaust gas, shown in Figure 18 C; Therefore, the impossible actual combustion temperature that takes place in the combustion chamber surpasses the situation of ignition temperature higher limit Tmax.

By doing like this, produce following advantageous effect: shown in fine line among Figure 18 A, the related art fuel cell that rises with excessive temperature is different, and the situation that ignition temperature surpasses ignition temperature higher limit Tmax can not take place, and can prevent the combustion catalyst degradation of combustion chamber.

In addition, when increasing from the air supply unit by 2 air supplied flow velocitys, perhaps when volume of air that reduction once was increased, the rate of change of limit air flow velocity can make air velocity gradually change, shown in Figure 18 B.

Therefore, has the advantageous effect that can be suppressed at the air pressure fluctuation that increase produces during 2 air supplied flow velocitys from the air supply unit.

Figure 19 is the flow chart that is set forth in system controller controlled function in the 7th embodiment.

At first, in S100, the cell voltage of fuel battery 3 is detected by voltage detector unit 36, and makes cell voltage whether less than the judgement of set-point (voltage threshold).If the voltage of each element cell that voltage detector unit 36 detects or the voltage of every group of element cell drop to below the voltage threshold, operation proceeds to S12.If these voltages surpass voltage threshold, operation is back to S100 so, thereby repeats the detection and the judgement thereof of cell voltage.

In addition, calculate the voltage threshold that uses when in S100, judging cell voltage in the following manner.

According to the value of

air themperature detector

29a or 29c detection, use tables of data calculating voltage threshold value shown in Figure 20.Set this tables of data, so that air themperature is high more, voltage threshold is big more, therefore along with air themperature increases, begins to increase the operation of air velocity in early days, and this will describe in detail below.Equally, although details is described below, because, the fluctuation of air pressure takes place easily, so for surge suppressing, executable operations makes rate of change (absolute value) minimum of the air velocity that will increase along with the increase of air themperature.By doing like this, because it is very long to increase the required time interval of air velocity, so along with the increase of air themperature, increase the feasible flow velocity that begins to increase air in early days of above-mentioned voltage threshold, thereby can before beginning to discharge anode exhaust, finish the increase of air.

In addition, according to the value that mass air flow sensor 32 detects, use the tables of data of in Figure 21, representing to calculate the voltage threshold that is used in S100, judging cell voltage.Set this tables of data, so that air velocity is high more, voltage threshold is big more, therefore begins to increase the operation of air velocity in early days.Equally, although details is described below, because, fluctuate easily, so for surge suppressing, executable operations makes rate of change (absolute value) minimum of the air velocity that will increase along with the increase of air velocity.By doing like this, because it is very long to increase the required time interval of air velocity, so along with the increase of air velocity, increase the feasible flow velocity that begins to increase air in early days of above-mentioned voltage threshold, thereby can before beginning to discharge anode exhaust, finish the increase of air.

The content of S12 to S16 shown in Figure 3 is identical in the content of operation of S12 to S16 and first embodiment.

Now, in S102, the rate of change of the air velocity that calculating will increase.

Calculate the rate of change of the air velocity that will increase herein, in the following manner.

Value according to mass air flow sensor 32 detections, use as shown in figure 23 lay in tables of data in system controller 37 in advance, the rate of change of the air velocity that calculating will increase (absolute value), tables of data shown in Figure 23 is the tables of data that allows from the air velocity rate of change of air velocity acquisition, and it is high more to be configured to air themperature, and the rate of change of air velocity (absolute value) is more little.When air themperature increases, because the increment rate of saturated steam amount increases, so atmospheric density a large amount of variations in the mode of air temperature variations.Therefore, in attempting to control the situation that air pressure maintains fixed value, the fluctuation of atmospheric density causes the marked change of control variables (for example opening degree of pressure-control valve), and therefore along with the increase of air themperature, air pressure is easy to fluctuation.Therefore, use tables of data shown in Figure 22 that following advantageous effect is provided: along with the increase of air themperature, air velocity increases gradually, and the result can suppress the fluctuation of air pressure during the air velocity increase stage.

In addition, calculate the rate of change (absolute value) of the air velocity that will increase in the following manner.

According to the value that mass air flow sensor 32 detects, use tables of data as shown in figure 23, the rate of change of the air velocity that calculating will increase (absolute value).Tables of data shown in Figure 24 is to describe an example of the tables of data of air velocity, from this tables of data, can obtain the air velocity rate of change (absolute value) that will increase, and the air velocity that is configured to circulate is big more, and the rate of change of air velocity (absolute value) is more little.If attempt to use butterfly valve control air pressure, so that control it and be under the fixed pressure, opening along with the increase of air velocity of valve increases, cause valve open aspect the reduction of air velocity sensitivity.Therefore, air velocity is big more, and aspect the air velocity variation, the variation that valve is opened is big more, thereby the fluctuation of air pressure takes place easily.So have following advantageous effect: by using tables of data shown in Figure 23, along with the increase of air velocity, air velocity increases gradually, thereby can during the air velocity increase stage, suppress the fluctuation of air pressure.

In addition, the rate of change of the air velocity that calculating will increase (absolute value), it have ended than the increase stage after, the bigger value that occurs during the air velocity reduction stage.Figure 24 is an example laying in the tables of data in system controller 37 in advance, and be illustrated in from air themperature when obtaining air velocity and changing, make the example that is higher than the air velocity rate of change (absolute value) during the air velocity reduction stage that dotted line is represented at the air velocity rate of change (absolute value) during the air velocity increase stage that solid line is represented.

When the air themperature according to above-mentioned

air themperature detector

29a or 29c detection, when calculating the rate of change (absolute value) of air velocity, the tables of data shown in the solid line is calculated the rate of change (absolute value) of the air velocity that will increase among use Figure 24.As previously mentioned, when using butterfly valve control air pressure, opening along with the increase of air velocity of valve increases, and the sensitivity of result's air velocity aspect the valve opening degree reduces.Therefore, when attempting when using F/B to control to implement air-pressure controlling, during air velocity increased, the F/B compensation variable that calculate was possible very big.When using PI control commonly used, I control variables (whole control variables) is got very big value.

Under this condition, if attempt to reduce fast the flow velocity of air, may take place owing to described F/B compensation variable, control variables is taked the situation of incorrect value temporarily, thereby causes the air pressure fluctuation.Therefore, has following advantageous effect: when the tables of data of using shown in Figure 24 dotted line, the value of the rate of change (absolute value) of air velocity during the rate of change (absolute value) of the air velocity that will calculate during the increase stage is by the reduction stage after ending has less than the air velocity increase stage, thereby not only when increasing air velocity, and can suppress the fluctuation of air pressure when after the increase stage, reducing air velocity.

In next step S104, air supply unit 2 begins to increase the flow velocity to negative electrode 5 air supplied.At this moment, according to the rate of change that calculates among the S102, implement to increase the operation of air velocity.

In S106, judge whether the increase of air velocity is finished.Detected value based on air velocity is judged, and under the situation that the increase operation has been done, operation proceeding to S18.

In S18, cleaning command is sent to anode off-gas discharge valve 27 and hydrogen supply unit 1 from system controller 37.When receiving described cleaning command, in S24, open anode off-gas discharge valve 27; And in S26, hydrogen supply unit 1 increases the flow velocity of the hydrogen of anode 4 supplies.

In S28 subsequently, judge whether given time interval Tp disappears from cleaning, if do not have, operation is back to S28.If from cleaning, given time interval Tp disappears, operation proceeds to S30.In S30, interrupt the increase of the hydrogen flow rate of 1 supply, and in S32, close anode off-gas discharge valve 27 from the hydrogen supply unit.

In the S108 that follows, the rate of change of the air velocity that calculating will increase.

At this moment, according to the value of

air themperature detector

29a or 29c detection, use tables of data as shown in figure 22, the rate of change of the air velocity that calculating will increase (absolute value).This tables of data is following to be determined: thus as described above, air themperature is high more, and the rate of change of air velocity (absolute value) is more little, and has following advantageous effect: along with the increase of air themperature, air velocity reduces gradually, and can suppress the fluctuation of air pressure during the reduction stage.

In addition, according to the value that pneumatic detector 32 detects, use tables of data as shown in figure 23, the rate of change of the air velocity that calculating will reduce (absolute value).Set this tables of data, so that as mentioned above, the air velocity of circulation is big more, the rate of change of air velocity (absolute value) is more little, and have following advantageous effect: along with the increase of air velocity, air velocity reduces gradually, and can suppress the fluctuation of air pressure during the reduction stage.

In addition, the rate of change (absolute value) of air velocity during the calculating reduction stage, it has the littler value of rate of change (absolute value) than air velocity during the increase stage.Has following advantageous effect: according to the tables of data shown in Figure 24 dotted line, the rate of change (absolute value) of air velocity during the calculating reduction stage, make not only when increasing air velocity, and when after the increase stage, reducing air velocity, can suppress the fluctuation of air velocity in above-mentioned described mode.

In the S110 that follows, air supply unit 2 begins to reduce the flow velocity to negative electrode 5 air supplied.At this moment, according to the rate of change that calculates among the S108, reduce air velocity, and air velocity is restored to initial condition.This makes fuel cell system be back to normal operating condition.

S40 to S52 is identical with the S40 to S52 of first embodiment shown in Fig. 3.

In addition, in first to the 7th embodiment, when forecast combustion temperature T e, come the forecast combustion temperature by the calculating of enthalpy that flows into or flow out the gas of combustion chamber, the figure that can use the ignition temperature shown in Figure 17 that fuel battery operation condition (cathode exhaust gas flow velocity and relative humidity) is drawn herein.

That is to say, collect in the prototype fuel cell measurement data, and, draw the figure of ignition temperature operating condition by using described data for each operating condition ignition temperature.And described chart is stored in the system controller 37, is used for the forecast combustion temperature.In this case, the static step of system controller program and the quantity of dynamic steps obviously reduce, thereby can be with mode realization system control relatively simply.

But, when using described chart forecast combustion temperature, because the situation that the ignition temperature prediction accuracy reduces may take place the adverse influence of the error of system flow rate control and atmospheric temperature aspect, preferably capping value Tmax is to the level that is lower than the ignition temperature that obtains based on enthalpy.

Industrial applicability

In above-mentioned the present invention, by by cleaning unit discharging anode exhaust the time, the temperature of burning gases never surpasses to fixed temperature in the control combustion chamber, has can suppress because the advantageous effect that the chamber performance that the excessive heat load causes reduces.

Date of filling is that Japanese patent application P2002-329978 number on November 13rd, 2002 and 2003-296773 number full content that date of filling is on August 20th, 2003 are incorporated herein for referencial use.

Described the present invention although consult particular of the present invention, the present invention is not restricted to above-mentioned embodiment, and according to described instruction, those those skilled in the art can make modification.Scope of the present invention is consulted following claim and is defined.

Claims

1, a kind of fuel cell system comprises:

The fuel gas feeding unit of fuel supplying gas;

The oxidant gas feeding unit of supply oxidant gas;

Use fuel gas and oxidant gas to produce the fuel battery of electric energy;

The anode exhaust that will go out from the anode exhaust of fuel battery is recycled to the anode exhaust recirculation unit on the anode;

Interim from anode exhaust recirculation unit with the cleaning unit of anode exhaust gas discharge to its outside;

At least burn the anode exhaust of from cleaning unit, discharging, from the oxidant gas of fuel battery cathode exhaust or the combustion chamber of cathode exhaust gas; And

Carry out the system controller of system's control operation, make that the ignition temperature of combustion chamber is no more than to fixed temperature when allowing cleaning unit to combustion chamber discharging anode exhaust.

2, according to the fuel cell system of claim 1, operating system controller wherein, service load based on fuel battery, flow velocity and the composition of predicting the mist that enters the combustion chamber are at least a, predict the outcome thereby provide, and based on predicting the outcome, the ignition temperature of forecast combustion chamber, thereby when the ignition temperature of judging prediction has surpassed to fixed temperature, executive system control, thus the prevention ignition temperature surpasses to fixed temperature.

3, according to the fuel cell system of claim 2, wherein the operating system controller is implemented control, if thereby when anode exhaust recirculation unit discharges anode exhaust temporarily, the ignition temperature of judging prediction has surpassed gives fixed temperature, increase will will be supplied to the oxidant gas of combustion chamber or the flow velocity of cathode exhaust gas thereby increase from the flow velocity of the oxidant gas of oxidant gas feeding unit supply.

4,, further comprise cooxidant gas supply unit to combustion chamber supply cooxidant gas according to the fuel cell system of claim 2;

Wherein the operating system controller is implemented control, if thereby when anode exhaust recirculation unit discharges anode exhaust temporarily, the ignition temperature of judging prediction has surpassed gives fixed temperature, from the cooxidant gas supply unit to combustion chamber accessory supplied cooxidant gas.

5, according to the fuel cell system of claim 2, wherein the operating system controller is implemented control, if thereby when anode exhaust recirculation unit discharges anode exhaust temporarily, the ignition temperature of judging prediction has surpassed gives fixed temperature, the anode exhaust flow velocity is set less than predetermined rate of discharge, and increases the drain time interval of anode exhaust.

6, according to the fuel cell system of claim 2, wherein the operating system controller is implemented control, if thereby when anode exhaust recirculation unit discharges anode exhaust temporarily, the ignition temperature of judging prediction has surpassed gives fixed temperature, do not change cathode exhaust gas flow velocity and anode exhaust gas discharge flow velocity, yet for once circulation, the drain time that anode exhaust is set is shorter than predetermined drain time at interval, and repeatedly discharges anode exhaust discontinuously.

7, according to the fuel cell system of claim 2, wherein the operating system controller is implemented control, if thereby when anode exhaust recirculation unit discharges anode exhaust temporarily, the ignition temperature of judging prediction has surpassed gives fixed temperature, supplies water with given flow velocity to the combustion chamber.

8, according to the fuel cell system of claim 3, operating system controller wherein comes the forecast combustion temperature by the calculating of enthalpy that flows into or flow out the gas of combustion chamber.

9, according to the fuel cell system of claim 3, wherein the operating system controller tentatively stores prior chart by the ignition temperature target exhaust emissions rate conditions of testing acquisition, and comes the forecast combustion temperature with reference to ignition temperature figure.

10, according to the fuel cell system of claim 1, wherein for the rate of change of limited flow rate, make before cleaning unit begins to discharge anode exhaust, the operating system controller, beginning increases from the oxidant feeding unit to the oxidant gas of combustion chamber supply or the flow velocity of cathode exhaust gas.

11, according to the fuel cell system of claim 1, wherein for the rate of change of limited flow rate, after ending the discharging anode exhaust, the operating system controller begins to reduce from the oxidant feeding unit to the oxidant gas of combustion chamber supply or the flow velocity of cathode exhaust gas.

12, according to the fuel cell system of claim 1, operating system controller wherein, restriction is from the rate of change of oxidant feeding unit to the flow velocity of the oxidant gas of combustion chamber supply or cathode exhaust gas, thereby from the oxidant gas of oxidant gas feeding unit to the combustion chamber supply, perhaps the rate of change absolute value of cathode exhaust gas reduces along with the increase of oxidant gas or cathode exhaust gas temperature.

13, according to the fuel cell system of claim 1, operating system controller wherein, in advance from the oxidant gas of oxidant feeding unit to combustion chamber supply, the perhaps flow velocity of cathode exhaust gas time of beginning to increase along with the increase of oxidant gas or cathode exhaust gas temperature.

14, according to the fuel cell system of claim 1, operating system controller wherein, restriction is from the oxidant gas of oxidant feeding unit to the combustion chamber supply, the perhaps change in flow rate of cathode exhaust gas, thus the absolute value of rate of change reduces along with the increase of oxidant gas or anode exhaust flow velocity.

15, according to the fuel cell system of claim 1, operating system controller wherein, in advance from the oxidant gas of oxidant feeding unit to combustion chamber supply, the perhaps flow velocity of cathode exhaust gas time of beginning to increase along with the increase of oxidant gas or cathode exhaust gas flow velocity.

16,, further comprise the oxidant gas pressure control unit of controlled oxidation agent gas or cathode exhaust gas pressure according to the fuel cell system of claim 1;

Operating system controller wherein, controlled oxidation agent gas pressure control unit, thereby during the flow velocity reduction stage after the flow velocity of oxidant gas that is supplied to the combustion chamber or cathode exhaust gas increases the stage, the oxidant gas that the absolute value of change in flow rate that makes the oxidant gas that is supplied to the combustion chamber or cathode exhaust gas is supplied during less than the increase stage or the absolute value of cathode exhaust gas flow velocity rate of change.

17, a kind of fuel cell system comprises:

The fuel gas feeding mechanism of fuel supplying gas;

The oxidant gas feeding mechanism of supply oxidant gas;

Use fuel gas and oxidant gas to produce the fuel battery of electric energy;

The anode exhaust that will go out from the anode exhaust of fuel battery is recycled to the anode exhaust EGR on the anode;

Temporarily from the anode exhaust EGR with the cleaning device of anode exhaust gas discharge to its outside;

At least burn the anode exhaust of from cleaning device, discharging, from the oxidant gas of fuel battery cathode exhaust or the combustion chamber of cathode exhaust gas; And

Carry out the system control device of system's control, make that the ignition temperature of combustion chamber is no more than to fixed temperature when allowing cleaning device to combustion chamber discharging anode exhaust.

18, a kind of method of controlling fuel cell system comprises:

The oxidant gas feeding unit of the fuel gas feeding unit of preparation fuel supplying gas, supply oxidant gas, use fuel gas and oxidant gas produce electric energy fuel battery, burn from the anode exhaust of anode exhaust gas discharge and from the oxidant gas of fuel battery cathode exhaust or the combustion chamber of cathode exhaust gas at least;

Anode exhaust anode exhaust from fuel battery;

Recirculation from the anode exhaust of fuel battery anode exhaust to anode;

At least burn from the anode exhaust of fuel battery anode exhaust, and from the oxidant gas or the cathode exhaust gas of fuel battery cathode exhaust; And

Executive system control makes that the ignition temperature of combustion chamber is no more than to fixed temperature when allowing anode exhaust gas discharge to the combustion chamber.