JP2006310291A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a fuel cell system, having high efficiency of fuel treatment system and high power generation efficiency, and capable of realizing energy-saving and economical operation. <P>SOLUTION: The fuel cell system has a combustor 10 which has integrated in common a starting burner for burning a starting fuel obtained through a starting fuel line 29 at starting of a fuel cell body 2 and a combustion burner for burning a power generation fuel at power generation of the fuel cell body 2, and is equipped with a fuel reformer 6 which performs fuel reforming by burning the fuel by the combustor 10 and supplies the reformed fuel to the fuel electrode of the main body 2, a process gas line 42 to transfer the fuel reformed by the reformer 6 to the fuel electrode of the body 2, an off-gas fuel line 30 to transfer the fuel remaining non-reacted at the main body 2 to the reformer 6, a degassing line 7 for degassing an inert gas existing in the process gas line 42 at starting before power generation of the body 2 and a shut-off valve for degassing 23 provided in the degassing line 17, and an off-gas fuel line check valve 24 which makes the starting fuel line 29 and the off-gas fuel line 29 communicate and separates them 29, 30 at starting before power generation of the body 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell system for obtaining electric energy by supplying, to a fuel cell, hydrogen obtained by extracting city gas or LPG and water vapor through a fuel reformer (reactor).

  In recent years, power supply systems for homes using fuel cells are considered promising in the future, and the technological development competition is becoming more intense among companies. In these systems, not only the use of battery power but also a cogeneration system that uses battery exhaust heat is common.

  There are many types of fuel cells depending on the type of electrolyte. For example, a polymer electrolyte fuel cell generates exhaust heat of about 100 ° C. or less with generation of electric energy. This indicates that the heat released from the high battery temperature to the ambient temperature is generated as heat unless the battery efficiency reaches 100%, that is, unless power generation is possible with the battery body temperature at the ambient temperature. Yes.

  On the other hand, also in a fuel processing system for reforming fuel to hydrogen, since a combustor is usually used for heating a reforming reaction of a reformer or the like, combustion exhaust gas or exhaust heat from the fuel processor is generated. These waste heats are suitable for hot water use such as hot water supply and baths, and if there is much heat recovery, the total efficiency of electricity and heat can be improved to nearly 80%. In other words, such cogeneration operation is more energy efficient than conventional grid power use, can save energy, is friendly to the global environment, and can be operated more economically. large.

  FIG. 4 is a schematic diagram showing an example of a conventional fuel cell system. As can be seen from the figure, the conventional reforming combustor 10 includes a start burner (start burner, hereinafter referred to as start burner) and a main burner (main burner, hereinafter referred to as power generation burner), and is disposed in the combustion chamber space. Since the two burners are arranged, the combustion chamber tends to be narrow, and there is a drawback that if the main fuel burner is arranged in the center, the starting burner must be arranged obliquely. In the case of this conventional example, the combustion of the start burner is premixed combustion, and the combustion of the main fuel burner is diffusion combustion. In addition, it is necessary to flow air for cooling the starter burner, and as a result, the flame shape of the main fuel burner drifts, and the thermal efficiency for heating the reforming catalyst tends to decrease.

  In the configuration of FIG. 4, the same parts as those in FIG. 1 for describing the embodiment of the present invention to be described later are denoted by the same reference numerals, and the description thereof is omitted.

  In such a fuel cell system, when the fuel is city gas or LPG mainly composed of methane, the reformer 6 for reforming the fuel gas into hydrogen is necessary, and the reforming catalyst is activated. In order to do so, a combustion device for heating is required. The burner used in this combustion device may be divided into two types: the burner used at start-up before power generation operation and the burner used at power generation, or it may be operated with only one type of burner having both functions. There is a case.

  The reason for switching between the two types of burners as in the former operation is that the main fuel is city gas or propane at start-up, hydrogen at power generation, and the combustion speed is different, so a stable flame is produced with one type of burner. This is because it is difficult to form.

In order to solve this problem, in the latter one type of burner, in order to achieve good and stable flammability, in Patent Document 1, the burner used at the start before the power generation operation and the burner used at the time of power generation are integrated into one type. The device is made like a burner (see Patent Document 1).
JP 2004-6111 A

  In the case of one type of burner that integrates the burner used at the start-up before the power generation operation and the burner used at the time of power generation, there is almost no problem in burning the assumed fuel gas with the burner alone.

  However, when the integrated burner is incorporated into the conventional fuel cell system of FIG. 4 and an attempt is made to smoothly shift the operation from the start-up to the power generation state, non-ignition and misfire occur at the start-up, and the start-up fuel changes to off-gas fuel. It has become difficult to continue burning.

  The present invention has been made to solve this type of problem, and an object of the present invention is to provide a fuel cell system with improved ignitability and combustion stability at startup and high power generation efficiency.

  In order to achieve the above object, an invention corresponding to claim 1 includes a burner used at the time of starting a fuel cell system, a combustor in which a burner used at the time of power generation of the fuel cell system is integrated, and a starting fuel in the combustor. In a fuel cell system comprising an activation fuel line for supplying gas and an off-gas fuel line for supplying off-gas fuel to the combustor and communicating the activation fuel line and the off-gas fuel line, when the fuel cell is activated before power generation A fuel cell system comprising means for separating the starting fuel line and the off-gas fuel line and enabling degassing of the process line.

  In order to achieve the above object, the invention corresponding to claim 2 is a fuel cell main body comprising an electrolyte membrane, a fuel electrode and an oxygen electrode, and obtaining electric energy by supplying fuel and air to the fuel electrode and oxygen electrode. And a starter burner that burns starter fuel obtained via a starter fuel line when the fuel cell body is started and a power generation burner that burns generated fuel when the fuel cell body generates power, and the starter burner, the power generation burner Provided with a combustor capable of supplying combustion air to the fuel, reforming the raw fuel by burning the fuel, and obtaining the reformed reformed fuel, and a fuel reformer from the fuel reformer A process gas line that transmits the reformed fuel to the fuel electrode of the fuel cell main body, and an off-gas that is communicated with the startup fuel line and that transmits unreacted fuel remaining in the fuel cell main body to the fuel reformer And charge line, a fuel cell system characterized by comprising a degassing means for degassing the inert gas present in the process gas in the line during power generation before activation of the fuel cell body.

  In order to achieve the above object, the invention corresponding to claim 3 comprises a fuel cell main body comprising an electrolyte membrane, a fuel electrode and an oxygen electrode, and obtaining electric energy by supplying fuel and air to the fuel electrode and oxygen electrode. And a starter burner that burns starter fuel obtained via a starter fuel line when the fuel cell body is started and a power generation burner that burns generated fuel when the fuel cell body generates power, and the starter burner, the power generation burner Provided with a combustor capable of supplying combustion air to the fuel, reforming the raw fuel by burning the fuel, and obtaining the reformed reformed fuel, and a fuel reformer from the fuel reformer A process gas line that transmits the reformed fuel to the fuel electrode of the fuel cell main body, and an off-gas that is communicated with the startup fuel line and that transmits unreacted fuel remaining in the fuel cell main body to the fuel reformer A fuel line, degassing means for degassing an inert gas present in the process gas line when the fuel cell main body is started before power generation, the starter fuel line and the offgas fuel line are communicated, and the fuel cell main body The fuel cell system further comprises a fuel flow blocking means for preventing starting fuel in the starting fuel line from flowing into the off-gas fuel line when starting before power generation.

  In order to achieve the above object, an invention corresponding to claim 10 comprises a fuel cell main body comprising an electrolyte membrane, a fuel electrode and an oxygen electrode, and obtaining electric energy by supplying fuel and air to the fuel electrode and oxygen electrode. A starting fuel line that performs fuel reforming of the raw fuel by burning the starting fuel when starting the fuel cell body and supplies the reformed fuel to the fuel reformer, and the startup A starting fuel line shut-off valve provided in a fuel line and opened when the fuel cell main body is started, and for fuel reforming of raw fuel to the fuel reformer, The starter burner for burning the starter fuel and the power generation burner for combusting the generated fuel at the time of power generation of the fuel cell main body, the starter burner, a combustor capable of supplying combustion air to the power generation burner, and the fuel reformer from A process gas line for transmitting quality fuel to the fuel electrode of the fuel cell body, and an off-gas fuel line that communicates with the starting fuel line and transmits unreacted fuel in the fuel cell body to the fuel reformer A check valve that is provided in the offgas fuel line and prevents the starting fuel from flowing out of the starting fuel line to the offgas fuel line, or provided in the offgas fuel line, and the flow path of the offgas fuel line An off-gas fuel line valve that closes the off-gas fuel line when the fuel cell body is started before power generation, and opens the off-gas fuel line when the fuel cell body is started before non-power generation, and the fuel Bypassing the battery body, one end is connected to the process gas line and the other end is connected to the exhaust side. A degassing line valve that is provided in the degassing line, opens the degassing line when the fuel cell body starts before power generation, and closes when the fuel cell body starts before power generation, and An activation fuel line valve provided in an activation fuel line, which opens the activation fuel line when the fuel cell body is activated before power generation; and is closed when the fuel cell body is activated before non-power generation; and activation of the combustor A common air supply path for supplying combustion air to each of the burner and the power generation burner is provided, provided in the middle of the air supply path, and opened when the fuel cell main body is started, to supply premixed combustion air and diffusion mixing air. The fuel cell body generates power for the combustion air switching valve, the start fuel line shut-off valve, the off-gas fuel line valve, the degassing line valve, and the combustion air switching valve that enable supply. A fuel cell system comprising: a controller that gives an opening / closing command in accordance with a pre-start state and a non-power generation start state.

  ADVANTAGE OF THE INVENTION According to this invention, the ignition property and combustion stability at the time of starting can improve, and a fuel cell system with high electric power generation efficiency can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3. As shown in FIG. 1, the embodiment of the present invention is generally configured as follows. That is, a fuel cell body that includes an electrolyte membrane (electrolyte body) 16, a fuel electrode (anode) 13, and an oxygen electrode (cathode) 14, and obtains electric energy by supplying fuel and air to the fuel electrode 13 and the oxygen electrode 14. 2 is provided.

  Further, a starter burner that burns fuel obtained via the starter fuel line 29 when the fuel cell main body 2 is started up and a power generation burner that burns generated fuel when the fuel cell main body generates power are integrated into the starter burner and the power generation burner. A combustor 10 capable of supplying combustion air is provided, and the reforming reaction by the endothermic reaction of the raw fuel is promoted by burning the fuel, whereby the fuel reforming is performed, and the reformed reformed fuel is obtained. A fuel reformer 6 is provided.

  Furthermore, the process gas line 42 that transmits the reformed fuel from the fuel reformer 6 to the fuel electrode of the fuel cell main body 2 and the starting fuel line 29 are communicated, and the fuel that remains unreacted in the fuel cell main body 2 Off-gas fuel line 30 transmitted to the fuel reformer 6 and degassing means such as a degassing line (bypass line) 17 for degassing the inert gas present in the process gas line 42 when the fuel cell main body 2 is started before power generation. And a deaeration shut-off valve (deaeration line valve) 23 provided in the middle of the deaeration line 17, an activation fuel line 29, and an off-gas fuel line 30 communicate with each other, and the activation is performed when the fuel cell body is activated before power generation. A fuel flow blocking means for blocking the flow of fuel between the fuel line 29 and the off gas fuel line 30, for example, an off gas fuel line check valve 24 is provided. In addition to this, similarly to the conventional example shown in FIG. 4, the gas fuel supply device 3, the fuel shutoff valve 20, the desulfurizer 4, the fuel pump 40, the switching valve 22, the steam flow rate adjusting valve 27, the steam The separator 9, the water switching valve 36, the tank 12, the tap water control valve 37, the hot water tank 35, the water pump 38, and the heat exchanger 28 are provided.

  In addition, a premix combustion method in which fuel and air are premixed, for example, a combustion air blower 26 and a combustion air switching valve 25 are provided upstream of the combustor 10 during the start-up operation before power generation of the fuel cell system. In addition, a diffusion combustion system, for example, a combustion air blower 26 that performs diffusion combustion by mixing off-gas fuel and air left unreacted in the fuel cell body 2 on the downstream side of the combustor 10 during power generation of the fuel cell body 2; Is a fuel cell system further provided.

  Further, the switching between the premixed combustion method and the diffusion combustion method is a fuel cell system further comprising means for spontaneously igniting the off-gas fuel with the residual heat of the premixed combustion and switching the combustion mode to diffusion combustion. .

  Next, an embodiment of the present invention will be specifically described. In other words, the off-gas fuel line 30 is provided, the flow path of the off-gas fuel line 30 can be opened and closed, the fuel cell body 2 closes the off-gas fuel line 30 when the fuel cell body 2 is started before power generation, and the fuel cell body 2 During startup, specifically during power generation operation (power generation combustion operation), the offgas fuel line 30 is functionally opened, for example, the offgas fuel line check valve 24 and the fuel cell main body 2 are bypassed, and one end thereof is A degassing line 17 connected to the process gas line 42 and having the other end communicating with the exhaust side, and a degassing line 17 are provided. When the fuel cell main body 2 is started before power generation, When the fuel cell body 2 is opened and the fuel cell main body 2 is started before power generation, specifically during the power generation operation (power generation combustion operation), the deaeration line valve, for example, the deaeration shut-off valve 23 and the start fuel line 29 are closed. When the fuel cell body 2 is started before power generation, the startup fuel line 29 is opened, and when the fuel cell body 2 is started before non-power generation, specifically during power generation operation (power generation combustion operation), the start is closed. It is detected by some means whether the state of the fuel line valve (starting fuel cutoff valve) 21 and the fuel cell main body 2 is a starting state before power generation or a starting state before non-power generation, and the valves 20, 21 are detected accordingly. , 23, 25, 29, 36, an opening / closing command is given, pumps 40, 38, 11 are given a start / stop command, and other blowers 26, 18, 15 are given a start / stop command. For example, a controller 41 such as a microcomputer is provided.

  Here, an example of the reformer 6 including the combustor 10 will be described with reference to FIGS. 2 and 3. The reformer 6 includes a combustor 123 (corresponding to 10 in FIG. 1), steam generators 105a and 105b (corresponding to 5 in FIG. 1), and a reformer body. Of these, the combustor 123 is a unit in which a starter burner for combusting starter fuel, which has been conventionally configured separately, and a power generation burner for combusting power generation fuel, that is, off-gas fuel, during power generation. Specifically, it is provided so as to communicate with the combustion chamber 125 formed in the interior of the container 122 of the reformer 6, and is, for example, a cylindrical member that penetrates the central axis position in the axial direction. Are formed on the outer peripheral side of the air jet 130, and a plurality of fuel jets 131 penetrating in the axial direction are formed. The outer peripheral side of each fuel jet 131 is formed in the axial direction. An annular air jet 132 penetrating therethrough is formed, and the off-gas fuel from the off-gas fuel line 30 is spontaneously ignited by spontaneous ignition, that is, by heating it above the ignition temperature of hydrogen.

  The reformer main body is, for example, a cylindrical reforming catalyst 124 disposed on the outer peripheral surface of the combustion chamber 125 inside the container 122, and the off-gas fuel can pass through the reforming catalyst 124, for example. For example, it is formed on the side surface of the container 122 so that the reformed hydrogen obtained by passing through the off-gas fuel intake port 125a and the reforming catalyst 124 formed on the bottom surface of the container 122 can be guided to the fuel cell body 13. And a hydrogen outlet 125b.

  The steam generator 105a includes a heat transfer tube 129a, a heat insulating member 126, and a heat insulating member 128, and the water vapor generator 105b includes a heat transfer tube 129b and a steam generating container 129b0, and is configured as follows. That is, the combustion exhaust gas exhaust port 122a formed through the bottom surface of the combustion chamber 125 formed inside the container 122, and the bottom surface of the combustion chamber 125 at the outer peripheral side of the combustion exhaust gas exhaust port 122a. In the combustion chamber 125, a cylindrical heat insulating member 128, a heat transfer pipe 129a that is disposed so as to surround the heat insulating member 128 on the outer peripheral side of the heat insulating member 128, and allows water in the tank 12 to pass therethrough. It is comprised between the outer peripheral side of the heat exchanger tube 129a and the outer peripheral surface of the combustion chamber 125, and comprises a bottomed cylindrical heat insulating member 126 disposed so that the bottom surface is on the top.

  With such a configuration, the combustion gas obtained in the combustion chamber 125 by the combustor 123 passes through the space between the inner peripheral wall where the reforming catalyst 124 is disposed and the heat insulating member 126, and the heat insulating member 126. While circulating around the heat transfer tube 129a disposed between the heat insulating members 128, the heat insulating member 128 enters the inside and is exhausted to the outside through the combustion exhaust gas exhaust port 122a.

  The steam generator 105b is formed on the outer peripheral side of the container 122 so as to surround the container 122, and includes a heat transfer pipe 129b through which water in the tank 12 passes, and a steam container 129b0 disposed around the heat transfer pipe 129b. I have.

  Here, a solid polymer fuel cell system will be described as an example, but the present invention is not limited to this, and other fuel cell system configurations may be used. This is mainly composed of a fuel processing system (FPS) 1 and a fuel cell main body (CSA; Cell Stack Assembly) 2.

  The fuel treatment system 1 includes a gas fuel supply device 3, a desulfurizer 4, a steam generator (steam heater) 5, a fuel reformer 6, a CO shift reactor 7, a CO selective oxidizer 8, a steam separator 9, It comprises a quality combustor 10, a reforming water pump 11, an exhaust heat exchanger & tank 12, and the like. The fuel supplied by the gas fuel supply device 3 is a hydrocarbon fuel, such as city gas or propane gas.

  On the other hand, the fuel cell body 2 includes a fuel electrode 13, an oxygen electrode 14, and an electrolyte membrane 16.

  Further, the parts common to the fuel processing system 1 and the fuel cell main body 2 include a cathode electrode air blower 15, a CO selective oxidizer air blower 18, and the like.

  Here, the principle of power generation will be briefly described. For example, when city gas is used as the fuel, reforming from city gas to hydrogen gas is performed in the fuel processing system 1. The gas fuel from the gas fuel supply device 3 passes through the desulfurizer 4, where sulfur is removed by, for example, activated carbon or zeolite adsorption, and then passes through the reformer 6. Water is heated by the steam generator 5 in front of this, and the gasified steam joins the fuel gas. In the reformer 6, hydrogen is generated from the reaction of city gas and water vapor by a catalyst, but at the same time, CO is also generated. Since this steam reforming is an endothermic reaction, the reformer 6 includes a combustor 10 for heating.

Polymer electrolyte fuel cell system, since the CO poisoning in the electrolyte membrane 16 and the catalyst layer of the fuel cell main body 2 composed of (not shown) MEA (Membrane Electrode Assembly) becomes a problem, CO is CO ₂ Need to be oxidized. For this reason, the CO shift reactor 7 needs to advance the shift reaction by H ₂ O, and the CO selective oxidizer 8 needs to advance the oxidation reaction by supplying air from the air blower 18 to the extent that CO poisoning is not generated by the catalyst. Although not shown for simplification, these catalytic reaction temperatures including the reformer 6 are different from each other, from several hundred degrees of the reformer 6 to hundreds of degrees of the CO selective oxidizer 8. Since the temperature difference between the upstream and downstream of the gas is large, a water heat exchanger for reducing the downstream temperature is actually required.

  Next, main process reactions in each catalyst are shown below. For example, in the case of city gas reforming mainly composed of a methane component, the steam reforming reaction is represented by equation (1), the CO shift reaction is represented by equation (2), and the CO selective oxidation reaction is represented by equation (3).

CH ₄ + 2H ₂ O → CO ₂ + 4H ₂ (1)
CO + H ₂ O → CO ₂ + H ₂ (2)
2CO + O ₂ → 2CO ₂ (3)
The reformed gas that has passed through the CO selective oxidizer 8 is mainly composed of hydrogen, carbon dioxide gas, excess steam, and the like. These gases are sent to the fuel electrode 13. The hydrogen gas sent to the fuel electrode 13 passes through the MEA catalyst layer, the proton H + passes through the electrolyte membrane 16, and is combined with oxygen and electrons in the air passing through the oxygen electrode 14 by the oxygen electrode air blower 15. Generated. Therefore, the fuel electrode 13 becomes a negative electrode and the oxygen electrode 14 becomes a positive electrode, and generates a DC voltage with a potential. If there is an electrical load between these potentials, it will function as a power source. The fuel electrode outlet gas remaining without being used for power generation is used as a combustion gas for heating the steam generator 5 and the reformer 6. Further, the water vapor in the outlet of the oxygen electrode 14 and the water vapor in the combustion exhaust gas are collected by the exhaust heat exchanger 12 to achieve water self-supporting in the system. The hot water heated by exchanging heat in the exhaust heat exchanger 12 is stored in the hot water storage tank 35 and used as hot water for the hot water supply or bath.

  Next, an operation method from the start-up of the fuel cell system closely related to the present invention to power generation will be described.

  The reformer 6 and its peripheral devices include a fuel cutoff valve 20, a start fuel line valve 21, a main fuel cutoff valve 22, a degassing cutoff valve 23, an offgas fuel check valve such as an offgas fuel line check valve 24, combustion air. It comprises a switching valve 25, a combustion air blower 26, a steam flow rate adjusting valve 27, and others.

  First, the operation method at the time of starting is shown. As shown in FIG. 2, when an operation start command is input to the controller 41, an open command is given to the combustion air switching valve 25, and the combustion air blower 26 is started with the combustion air switching valve 25 open. Then, the combustion chamber in the reformer 6 is purged with air. In this case, the combustion air is supplied from the combustion air blower 26 not only as premixed air for the starting fuel but also as diffusion air into the combustion chamber.

  When the air purge in the combustion chamber is completed, a spark from, for example, a spark plug (not shown) for starting fuel ignition is generated in the combustion chamber. When the fuel cutoff valve 20 and the startup fuel line valve 21 are opened with the main fuel cutoff valve 22 closed and the deaeration cutoff valve 23 opened, the startup fuel that has passed through the fuel cutoff valve 20 and the startup fuel line valve 21 Is ignited in the combustion chamber to form a flame. The burner used in the combustion chamber is an integrated burner for both start-up and power generation, and methane-based starter fuel has a lower combustion speed than hydrogen-based fuel, which is off-gas fuel during power generation, and is easily blown out. The premixed combustion improves the combustibility.

  Combustion continues, the reformer 6 is heated by the combustion gas, and the CO shift reactor 7, the CO selective oxidizer 8, the steam separator 9, and the like heated by an electric heater (not shown), etc. When the temperature is reached, the steam flow rate adjusting valve 27 is opened and steam is supplied from the steam separator 9, then the main fuel shut-off valve 22 is opened, and fuel is supplied into the fuel processing system 1 to start the reforming reaction. At the same time as the off-gas fuel that has passed through the fuel electrode 13 is ignited by the combustor 10, the starting fuel line valve 21, the deaeration cutoff valve 23, and the combustion air switching valve 25 are closed.

  Here, the role of the off-gas fuel line check valve 24 and the deaeration shut-off valve 23 will be described. First, shortly after the start-up operation is started, the pressure loss in the burner section that performs premixed combustion is relatively large. Therefore, if the off-gas fuel line check valve 24 is not provided, the start-up fuel burns through the burner section. Since the fuel flows not only to the chamber side but also to the off-gas fuel line side, the amount of fuel required for the start-up combustion is reduced and the fuel becomes lean, the combustion is likely to become unstable, and misfire is likely to occur. Eventually, as the temperature of the reformer 6 rises, the temperature of the inert gas such as water vapor and nitrogen accumulated in the process gas line expands, and if the reformer 6 is supplied with the reforming fuel, it is used for degassing. If the shut-off valve 23 is not open, there is no place for these inert gases to escape, and this time, the inert gas enters the starting fuel line from the off-gas line and the combustion state becomes unstable, resulting in misfire. To put it simply, both valves are considered to be indispensable parts for stable combustion of starting fuel.

  The reason why the inert gas tends to remain in the process gas line 42 at the time of start-up is that nitrogen or steam purge is required at the time of start-up or stop in order to drive out the remaining fuel. The deaeration shut-off valve 23 is closed at the same time as the reformed fuel is supplied, so that the process gas is not released to the atmosphere while remaining unburned.

Return the explanation to the operating state of the plant. After the reforming reaction has started, the reformed gas exiting from the outlet of the CO selective oxidizer 8 is mainly composed of components such as hydrogen, carbon dioxide, and water vapor, and is supplied to the fuel electrode (anode electrode) 13 of the battery body 2. The inverter is activated (not shown) and power generation begins. When the reformed gas is supplied to the fuel electrode 13, the proton gas H ⁺ flows through the electrolyte membrane 16 through the catalyst layer (not shown) of the membrane electrode assembly MEA, and the oxygen gas is supplied from the oxygen electrode air blower 15. It combines with oxygen and electrons in the air supplied to the pole 14 to generate water. Accordingly, the fuel electrode 13 becomes a negative (−) electrode and the oxygen electrode 14 becomes a positive (+) electrode, and generates DC power with a potential.

  When an electric load is present between these potentials, a function as a power source can be provided. On the other hand, the off-gas exiting from the outlet of the fuel electrode 13 remaining without contributing to power generation passes through the off-gas fuel line check valve 24 and is then supplied to the reforming combustor 10.

  The start-up fuel and air supplied to the reforming combustor 10 are already shut off, and the temperature of the combustion chamber starts to decrease, but is still sufficiently high to ignite off-gas hydrogen main fuel. Therefore, the off-gas fuel supplied to the reforming combustor 10 is easily ignited and starts stable diffusion combustion with the main fuel air. Thereafter, oxygen electrode air is supplied to the battery body 2, and when the inverter starts, power generation of the fuel cell body 2 starts.

  In the case of one type of burner in which the above-described start burner used at start-up before power generation operation and the power generation burner used during power generation are integrated, the burner alone has almost no problem in burning assumed fuel gas. However, an integrated burner can be incorporated into a conventional fuel cell system, and the operation can be smoothly transferred from start to power generation, non-ignition at start-up can be prevented, and misfire can be prevented. It is easy to continue burning.

  As a result, according to the fuel cell system of the present embodiment, the ignitability and combustion stability at the time of start-up are improved, so that the efficiency and power generation efficiency of the fuel processing system 1 are high, and it is friendly to the global environment and is very energy saving. Economic operation can be realized.

  Thus, in the embodiment of the present invention shown in FIG. 1, since the burner is integrated, not only the flame shape is uniform and the thermal efficiency is improved, but also the effect of reducing the equipment cost is great.

  According to the embodiment described above, the following operational effects can be obtained.

  1) In a system flow configuration in which a burner in which combustion at startup and power generation is commonly integrated is arranged, during startup operation before power generation, the startup fuel line 29 and the offgas fuel line 30 are disconnected, and the offgas fuel line 30 is deaerated. Therefore, the ignitability at start-up and the combustion stability are improved, and a flame can be uniformly formed in the combustion chamber space during start-up and power generation operation. Thereby, the fuel processor efficiency at the time of power generation operation becomes high, and it is possible to realize an economical and energy efficient operation with high power generation efficiency.

  2) During start-up before power generation, premixed combustion is performed by premixing fuel and air upstream of the burner. During power generation, diffusion combustion is performed by mixing fuel and air downstream of the burner. In addition, combustion stability and safety during power generation are improved, and a flame can be uniformly formed in the combustion chamber space during startup and power generation operation. Thereby, the fuel processor efficiency at the time of power generation operation becomes high, and it is possible to realize an economical and energy efficient operation with high power generation efficiency.

  3) When switching from premixed combustion to diffusion combustion, the hydrogen main off-gas fuel is spontaneously ignited by the residual heat of premixed combustion, and the combustion mode is switched to diffusion combustion. Therefore, combustion stability at startup, power generation, and transition Safety can be improved, and a flame can be uniformly formed in the combustion chamber space during startup and power generation operation. Thereby, the fuel processor efficiency at the time of power generation operation becomes high, and it is possible to realize an economical and energy efficient operation with high power generation efficiency.

  4) Since the off-gas fuel line check valve 24 is provided in the off-gas fuel line 30 so that the fuel does not flow from the starting fuel line 29 to the off-gas fuel line 30, the ignitability and combustion stability at the time of starting are improved. A flame can be formed uniformly in the combustion chamber space during startup and power generation operation. Thereby, the fuel processor efficiency at the time of power generation operation becomes high, and it is possible to realize an economical and energy efficient operation with high power generation efficiency.

(Modification)
The present invention is not limited to the above-described embodiment, and can be modified as follows.

  (1) In the above embodiment, the offgas fuel line check valve 24 is provided in the offgas fuel line 30 so that the starting fuel does not flow from the starting fuel line to the offgas fuel line. The stop valve 24 may be replaced with an electromagnetic valve and operated by the controller 41.

  (2) Further, for example, an electromagnetic shut-off valve is provided as the degas shut-off valve 23 provided in the degas line 17 bypassing the off-gas fuel line 30, but the present invention is not limited to this, and other valves may be used. The deaeration shut-off valve 23 is operated by the controller 41, that is, the deaeration shut-off valve 23 is opened during the start-up combustion operation before power generation so that the heated expansion gas inside the fuel processing system 1 is deaerated to the atmosphere. With this configuration, the ignitability and combustion stability at the time of startup are improved, and a flame can be uniformly formed in the combustion chamber space during startup and power generation operation. As a result, the efficiency of the fuel processor during the power generation operation is increased, so that the operation with high power generation efficiency and economy and high energy efficiency can be realized.

  (3) Further, the deaeration cutoff valve 23 provided in the deaeration line 17 bypassing the off-gas fuel line 30 is operated by the controller 41, that is, the deaeration cutoff valve 23 is closed during the power generation operation. Thus, combustion stability during power generation is improved, and a flame can be uniformly formed in the combustion chamber space during startup and power generation operation. As a result, the efficiency of the fuel processor during the power generation operation is increased, so that the operation with high power generation efficiency and economy and high energy efficiency can be realized.

  (4) The aforementioned deaeration line 17 is configured to bypass the off-gas fuel line 30 and communicate with the exhaust port. The deaeration line 17 is provided with an electromagnetic shut-off valve, and the start-up combustion operation before power generation is performed during the start-up combustion operation. By operating the controller 41 so as to open the electromagnetic shut-off valve, it becomes possible to deaerate to the atmosphere from the exhaust port, and the ignitability and combustion stability at the time of startup are improved, and during startup and power generation operation A flame can be formed uniformly in the combustion chamber space. As a result, the efficiency of the fuel processor during the power generation operation is increased, so that the operation with high power generation efficiency and economy and high energy efficiency can be realized.

(5) Further, the off-gas fuel line check valve 24 provided in the off-gas fuel line 30 of the above-described embodiment is not provided, but an electromagnetic valve that operates by an electric signal is provided instead, and the start-up fuel line 29 is provided. The fuel line valve 21 is an electromagnetic valve, and the electromagnetic valve and the electromagnetic valve are configured to be operated by the controller 41 so that the former electromagnetic cutoff valve is closed and the latter electromagnetic cutoff valve is opened during the power generation combustion operation. Thus, the main fuel can be prevented from flowing out from the off-gas fuel line 30 to the starting fuel line 29, the combustion stability during power generation is improved, and the flame is evenly distributed in the combustion chamber space during the starting and power generating operation. Can be formed. As a result, the efficiency of the fuel processor during the power generation operation is increased, so that the operation with high power generation efficiency and economy and high energy efficiency can be realized.

  (6) In the above-described embodiment, the case where the off-gas fuel is ignited in the combustor 123 by the natural ignition method has been described. However, depending on the installation location of the fuel cell system, a high voltage may be used instead of the above-mentioned natural ignition method. You may make it ignite by the ignition means which combined the transformer and the spark rod. In this case, the spark rod is embedded in, for example, an intermediate position between the air outlet 130 and the fuel outlet 131 in FIG.

The system diagram which shows schematic structure of embodiment which concerns on the fuel cell system of this invention. FIG. 2 is a longitudinal sectional view showing an example of a fuel reformer in FIG. 1. Sectional drawing cut | disconnected along the AA line of FIG. 2 and looked at the arrow direction. The system diagram which shows schematic structure of an example of the conventional fuel cell system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel processing system, 2 ... Fuel cell main body, 3 ... Gas fuel supply device, 4 ... Desulfurizer, 5 ... Steam generator, 6 ... Fuel reformer, 7 ... CO shift reactor, 8 ... CO selective oxidizer , 9 ... Steam separator, 10 ... Reforming combustor, 11 ... Reforming water pump, 12 ... Tank, 12 ... Waste heat exchanger, 13 ... Fuel electrode, 14 ... Oxygen electrode, 15 ... Air for oxygen electrode Blower, 16 ... electrolyte membrane, 17 ... deaeration line, 18 ... air blower for CO selective oxidizer, 20 ... fuel cutoff valve, 21 ... startup fuel line valve, 22 ... main fuel cutoff valve, 23 ... deaeration line valve (degassing) Shutoff valve for gas), 24 ... off gas fuel line check valve, 25 ... combustion air switching valve, 26 ... combustion air blower, 27 ... steam flow control valve, 28 ... heat exchanger, 29 ... starting fuel line, 30 ... Off-gas fuel line, 35 ... Hot water tank, 41 ... Controller, 42 ... Process Gas line, 105a ... combustion unit, 105b ... steam generation unit, 122 ... vessel, 123 ... combustor, 124 ... reforming catalyst, 125 ... combustion chamber, 126 ... heat insulation member, 127 ... compartment chamber, 128 ... heat insulation member, 129a ... heat transfer tube, 129b ... heat transfer tube, 130 ... air jet, 131 ... fuel jet, 132 ... air jet.

Claims (10)

A burner used at the start of the fuel cell system, a combustor integrated with a burner used at the time of power generation of the fuel cell system, a start fuel line for supplying start fuel to the combustor, and an off-gas fuel to the combustor A fuel cell system comprising: an off-gas fuel line that communicates with the start-up fuel line; and the off-gas fuel line;
A fuel cell system comprising means for separating the startup fuel line and the off-gas fuel line at the time of startup of the fuel cell before power generation, and enabling the process line to be deaerated. A fuel cell main body comprising an electrolyte membrane, a fuel electrode and an oxygen electrode, and obtaining electric energy by supplying fuel and air to the fuel electrode and the oxygen electrode;
A starter burner that burns starter fuel obtained via a starter fuel line at the time of start-up of the fuel cell main body and a power generation burner that burns power generation fuel at the time of power generation of the fuel cell main body are integrated, and the starter burner and the power generation burner burn A fuel reformer that includes a combustor capable of supplying air, performs fuel reforming of the raw fuel by burning the fuel, and obtains the reformed reformed fuel;
A process gas line for transmitting the reformed fuel from the fuel reformer to the fuel electrode of the fuel cell body;
An off-gas fuel line that communicates with the startup fuel line and transmits unreacted fuel remaining in the fuel cell body to the fuel reformer;
A degassing means for degassing an inert gas present in the process gas line when the fuel cell body is activated before power generation;
A fuel cell system comprising: A fuel cell main body comprising an electrolyte membrane, a fuel electrode and an oxygen electrode, and obtaining electric energy by supplying fuel and air to the fuel electrode and the oxygen electrode;
A starter burner that burns starter fuel obtained via a starter fuel line at the time of start-up of the fuel cell main body and a power generation burner that burns power generation fuel at the time of power generation of the fuel cell main body are integrated, and the starter burner and the power generation burner burn A fuel reformer that includes a combustor capable of supplying air, performs fuel reforming of the raw fuel by burning the fuel, and obtains the reformed reformed fuel;
A process gas line for transmitting the reformed fuel from the fuel reformer to the fuel electrode of the fuel cell body;
An off-gas fuel line that communicates with the startup fuel line and transmits unreacted fuel remaining in the fuel cell body to the fuel reformer;
A degassing means for degassing an inert gas present in the process gas line when the fuel cell body is activated before power generation;
A fuel flow blocking means for communicating the starting fuel line and the off-gas fuel line, and for preventing the starting fuel of the starting fuel line from flowing into the off-gas fuel line when the fuel cell main body is started before power generation;
A fuel cell system comprising:   At the time of start-up operation before the power generation of the fuel cell system, a premixed combustion method in which a part of fuel and air is premixed on the upstream side of the combustor is used, and at the time of power generation of the fuel cell system, The fuel cell system according to any one of claims 1 to 3, wherein a diffusion combustion system is used in which diffusion combustion is performed by mixing unreacted off-gas fuel and air on the side. .   The switching between the premixed combustion method and the diffusion combustion method further comprises means for causing the off-gas fuel to spontaneously ignite with the residual heat of the premixed combustion and switching the combustion mode to diffusion combustion. 5. The fuel cell system according to 4.   The switching between the premixed combustion method and the diffusion combustion method is characterized by further comprising means for igniting the off-gas fuel by ignition means with residual heat of the premixed combustion and switching the combustion mode to diffusion combustion. The fuel cell system according to claim 4.   4. The check valve according to claim 3, wherein the fuel flow blocking means is a check valve that is provided in the off-gas fuel line and prevents the start-up fuel from flowing out of the start-up fuel line to the off-gas fuel line. Fuel cell system.   4. The fuel cell system according to claim 3, wherein the fuel flow blocking means is a valve that is provided in the off-gas fuel line and that closes the off-gas fuel line when the fuel cell main body is activated before power generation.   The degassing means bypasses the fuel cell main body, one end thereof is connected to the process gas line, and the other end is provided to communicate with the exhaust side, and is provided in the degassing line and the degassing line, The fuel cell system according to claim 2 or 3, further comprising a valve that opens the deaeration line when the fuel cell system is started before power generation. A fuel cell main body comprising an electrolyte membrane, a fuel electrode and an oxygen electrode, and obtaining electric energy by supplying fuel and air to the fuel electrode and the oxygen electrode;
A startup fuel line for performing fuel reforming of the raw fuel by burning the startup fuel at the startup of the fuel cell main body and supplying the fuel reformer to obtain the reformed reformed fuel;
An activation fuel line shut-off valve provided in the activation fuel line and opened when the fuel cell body is activated;
A fuel reformer for reforming raw fuel to the fuel reformer, comprising: a starting burner for burning the starting fuel; and a power generating burner for burning the generated fuel during power generation of the fuel cell body. A combustor that is integrated and capable of supplying combustion air to the startup burner and the power generation burner;
A process gas line for transmitting the reformed fuel from the fuel reformer to the fuel electrode of the fuel cell body;
An off-gas fuel line that communicates with the startup fuel line and transmits unreacted fuel remaining in the fuel cell body to the fuel reformer;
A check valve provided in the off-gas fuel line to prevent the starting fuel from flowing out of the starting fuel line into the off-gas fuel line, or provided in the off-gas fuel line, and the flow path of the off-gas fuel line is opened and closed An off-gas fuel line valve that closes the off-gas fuel line when the fuel cell body is activated before power generation and opens the off-gas fuel line when the fuel cell body is activated before power generation;
Bypassing the fuel cell body, one end thereof is connected to the process gas line, and the other end is provided to communicate with the exhaust side, and a deaeration line;
A degassing line valve that is provided in the degassing line, opens the degassing line when the fuel cell body starts before power generation, and closes when the fuel cell body starts before power generation; and
An activation fuel line valve that is provided in the activation fuel line, opens the activation fuel line when the fuel cell main body is activated before power generation, and closes when the fuel cell main body is activated before non-power generation;
A common air supply passage for supplying combustion air to the startup burner and the power generation burner of the combustor, provided in the middle of the air supply passage, and opened when the fuel cell main body is started; A combustion air switching valve that enables supply of diffusion mixing air;
The fuel cell body opens and closes with respect to the start fuel line shut-off valve, the off-gas fuel line valve, the degassing line valve, and the combustion air switching valve according to the start state before power generation and the start state before non-power generation And a controller for giving a command.

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