JP2012079409A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system preventing occurrence of carbon deposition, reforming catalyst degradation and others that can be caused at the time of restart and enabling long life operation.SOLUTION: A fuel cell system 1 includes a reformer 20 and a control unit 110, and the control unit 110 is configured to perform (1) control of heating the reformer by combustion heat due to fuel gas when the temperature of the reformer is less than a partial oxidation and reforming reaction start temperature (T1), (2) a POX process when the temperature of the reformer is T1 or more and less than a steam reforming reaction possible temperature (T2) and (3) an ATR process when the temperature of the reformer is T2 or more, in this order in a start-up control of the fuel cell system 1. The control unit 110 does not start a start-up control from the ATR process when the temperature of the reformer 20 at the time of starting a start-up control of the fuel cell system 1 is T2 or more, and performs the POX process after the temperature of the reformer 20 declines to less than T2.

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system capable of shortening a startup time at the time of restart.

  Conventionally, in a solid oxide fuel cell (SOFC), at start-up, each partial start-up reforming reaction (POX), autothermal reforming reaction (ATR), and steam reforming reaction (SR) of the fuel gas is started in the reformer. It is known that the temperature of the reformer and the like is increased in order according to the stage.

  In such a fuel cell, when restarting during the operation stop operation from the operation state or after the operation stop state, in the state where the residual heat is still accumulated in the fuel cell module, all of the above POX, ATR, SR It is possible to shift to SR (or ATR) without sequentially executing the reaction steps, that is, without performing POX (see, for example, Patent Document 1). By omitting POX in this way, the restart time can be shortened.

JP 2008-159463 A JP 2005-340075 A

  However, when starting from SR when the reformer is in a high temperature state at the time of restarting, there is a problem that carbon deposition or deterioration of the reforming catalyst occurs. That is, when starting from SR, it is necessary to ensure that the fuel gas and water supply start timings coincide with each other. If these supply timings do not coincide with each other and water supply is delayed or insufficiently supplied, carbon deposition occurs. On the other hand, when the water is supplied excessively, the reforming catalyst is deteriorated.

  For example, Patent Document 2 relates to a method for stopping a fuel cell. However, Patent Document 2 describes that when only water vapor is supplied to a catalyst layer in a high temperature region at the time of stop, water vapor is used as an oxygen source to oxidize the catalyst. It points out the problem of end.

  Further, the reformer is disposed, for example, in the fuel cell module, and at the time of restart, the reformer may be locally hot due to temperature variations in the fuel cell module. Therefore, even if the measured temperature of the reformer is low, there is a possibility that a high temperature region exists locally. When the steam reforming (SR) is started in such a state, the above-described carbon deposition or the like occurs. There was a problem that it occurred.

  The present invention has been made in order to solve such problems, and provides a fuel cell system capable of preventing the occurrence of carbon deposition or reforming catalyst deterioration that may occur at the time of restart and enabling a long-life operation. The purpose is to do.

  In order to achieve the above object, the present invention provides a fuel cell system including a reformer for supplying a reformed fuel gas to a fuel cell and a control means, the control means comprising a fuel cell In the start-up control of the battery system, (1) a heating step of heating the reformer with combustion heat from the fuel gas when the temperature of the reformer is lower than the partial oxidation reforming reaction start temperature (T1); When the reformer temperature is equal to or higher than the partial oxidation reforming reaction start temperature (T1) and lower than the steam reforming reaction possible temperature (T2), the reaction heat of the partial oxidation reforming reaction of the fuel gas and the combustion heat of the combustion gas POX process for heating the reformer, and (3) When the reformer temperature is equal to or higher than the steam reforming temperature (T2), the partial oxidation reforming reaction of the fuel gas and the steam reforming reaction are used in combination. Auto-thermal reforming reaction is performed to improve partial oxidation of fuel gas The reaction heat of the reaction, the heat of combustion by the fuel gas, and the ATR process of heating the reformer by controlling the heat absorption of the steam reforming reaction of the fuel gas, and the control means comprises the fuel When the temperature of the reformer at the time of starting the start control of the battery system is equal to or higher than the steam reforming reaction possible temperature (T2), the temperature of the reformer is changed to the steam without starting the start control from the ATR process. It is characterized in that the POX process is performed after the temperature falls below the reforming reaction possible temperature (T2).

  When the fuel cell system is started or restarted when the temperature of the reformer is equal to or higher than the steam reforming reaction possible temperature (T2) (that is, the temperature range corresponding to the ATR process), the deterioration of the reformer in a high temperature environment ( That is, in order to prevent the occurrence of carbon deposition or catalyst deterioration due to the insufficient or excessive water supply amount), it is necessary to cause water and fuel gas to reach the reforming catalyst simultaneously. However, it is difficult to control so that water and fuel gas reach the reforming catalyst at the time of restart.

Therefore, in the present invention, when the temperature of the reformer at the time of starting the restart control is equal to or higher than the steam reforming reaction possible temperature (T2), the normal start that starts the start control from a low temperature or normal temperature state Unlike the time, even if the reformer temperature is equal to or higher than the steam reforming reaction possible temperature (T2), the start control is not started from the ATR process, and the reformer temperature is lower than the steam reforming possible temperature (T2). After the decrease, the activation control is started from the POX process. In the POX process, the steam reforming reaction that requires water supply is not performed, and it is not necessary to precisely control the supply timing of water and fuel gas, so the above-mentioned problems such as carbon deposition and catalyst deterioration are surely avoided. can do. In the POX process, instead of the steam reforming reaction, an oxidation reaction of fuel gas with air is performed. However, in this reaction, it is not necessary to supply the air and the fuel gas at the same time, so the control is simplified. be able to.
Further, in the present invention, since the reformer temperature is shifted to the temperature raising step when the temperature of the reformer falls below the steam reforming reaction possible temperature (T2), the normal start-up is performed after the reformer temperature is lowered to room temperature. Compared with the case where control is executed, the startup time can be shortened.

  In the present invention, preferably, the control means performs the POX step after the temperature of the reformer is lowered to a temperature lower than the steam reforming reaction possible temperature (T2), and the temperature of the reformer is the partial oxidation reforming reaction start temperature. The control content is executed differently from the POX process in the normal startup control started from a state less than (T1).

  Even if the temperature of the reformer falls below the steam reforming reaction possible temperature (T2), the residual heat is accumulated in the entire fuel cell module. For this reason, if the normal POX process (exothermic reaction) is performed, the temperature raising rate of the reformer may become too high compared to the fuel cell, and in this case, the reformer overheats and reforms. There is a risk of deterioration. For this reason, in the present invention, in the restart control, even if the reformer is cooled to a temperature at which the POX process can be performed, the normal POX process is not performed and the restart is performed by starting POX different from normal. It is possible to prevent excessive temperature rise at the time.

In the present invention, it is preferable that the control means performs the POX process performed after the temperature of the reformer is lowered to a temperature lower than the steam reforming reaction possible temperature (T2) than the POX process in the normal start-up control. Control to reduce the amount.
At the time of restarting, since the remaining heat has already accumulated in the reformer, the temperature raising rate of the reformer tends to be too high. In the present invention, however, the POX process with reduced calorific value is executed. As a result, it is possible to reliably prevent overheating of the reformer.

In the present invention, preferably, the control means shortens the time of the POX process performed after the temperature of the reformer falls below the steam reforming reaction possible temperature (T2) as compared with the POX process in the normal start-up control. It is configured.
In the present invention configured as described above, excessive temperature rise can be prevented by terminating the POX process, which is an exothermic reaction, in a short time and shifting to the ATR process.

In the present invention, preferably, the control means is configured not to start the POX process until the temperature of the reformer decreases to a predetermined temperature lower than the steam reforming reaction possible temperature (T2).
Even if the temperature measurement value of the reformer falls below the steam reforming reaction possible temperature (T2), there is a possibility that it is locally T2 or more at a specific part other than the measurement part. Therefore, if the process shifts to the POX process at this time, there is a possibility that the temperature of the specific part is excessively increased due to the exothermic reaction of POX, and the reforming catalyst is oxidized.
For this reason, in the present invention, the measured temperature value is lowered to a predetermined temperature at which the entire reformer is surely T2 or less, and then the process proceeds to the POX process. It is possible to prevent an excessive temperature rise at.

In the present invention, preferably, the steam reforming reaction possible temperature (T2) is 350 ° C. or higher, and the predetermined temperature is set to be 100 ° C. or lower lower than the steam reforming reaction possible temperature (T2).
In the present invention configured as described above, the process does not proceed to the POX process until the measured temperature of the reformer is lowered to a temperature lower than T2 by 100 ° C. or more. Even if it exists, it can prevent exceeding the temperature (350 degreeC) which performs catalytic oxidation in the said site | part.

  In the present invention, preferably, the control means obtains the inlet temperature and the outlet temperature of the reformer, respectively, transitions to the POX process after the inlet temperature decreases to a predetermined temperature, and the outlet temperature is higher than the predetermined temperature. When the temperature exceeds a predetermined temperature, the supply amount of fuel gas and air in the POX process is increased.

  Heat generation due to the POX reaction is most likely to occur near the inlet of the reformer. For this reason, in this invention, after confirming that inlet temperature fell to predetermined temperature, it transfers to a POX process, and the malfunction by local excessive temperature rise can be prevented. Furthermore, in the present invention, until the outlet temperature rises (that is, until it is confirmed that the temperature rise due to the combustion flame has spread throughout), the fuel amount and the air amount are reduced to make the local amount small. An excessive temperature rise can be suppressed more reliably.

  According to the fuel cell system of the present invention, it is possible to prevent the occurrence of carbon deposition, reforming catalyst deterioration, or the like that may occur at the time of restart, and to enable a long-life operation.

1 is an overall configuration diagram showing a fuel cell system according to an embodiment of the present invention. It is a front sectional view showing a fuel cell module of a fuel cell system by one embodiment of the present invention. It is sectional drawing which follows the III-III line of FIG. It is a fragmentary sectional view showing a fuel cell unit of a fuel cell system by one embodiment of the present invention. 1 is a perspective view showing a fuel cell stack of a fuel cell system according to an embodiment of the present invention. 1 is a block diagram showing a fuel cell system according to an embodiment of the present invention. It is a time chart which shows the operation | movement at the time of starting of the fuel cell system by one Embodiment of this invention. It is a time chart which shows the operation | movement at the time of the driving | operation stop of the fuel cell system by one Embodiment of this invention. It is a restart control processing flow of the fuel cell system by one Embodiment of this invention. It is a restart control processing flow of the fuel cell system by other embodiment of this invention. It is a figure which shows the starting mode at the time of normal of the fuel cell system by one Embodiment of this invention, and the starting mode at the time of restart.

Next, a solid oxide fuel cell (SOFC) according to an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is an overall configuration diagram showing a solid oxide fuel cell (SOFC) according to an embodiment of the present invention. As shown in FIG. 1, a solid oxide fuel cell (SOFC) 1 according to an embodiment of the present invention includes a fuel cell module 2 and an auxiliary unit 4.

  The fuel cell module 2 includes a housing 6, and a sealed space 8 is formed inside the housing 6 via a heat insulating material (not shown, but the heat insulating material is not an essential component and may not be necessary). Is formed. In addition, you may make it not provide a heat insulating material. A fuel cell assembly 12 that performs a power generation reaction with fuel gas and an oxidant (air) is disposed in a power generation chamber 10 that is a lower portion of the sealed space 8. The fuel cell assembly 12 includes ten fuel cell stacks 14 (see FIG. 5), and the fuel cell stack 14 includes 16 fuel cell unit 16 (see FIG. 4). Yes. Thus, the fuel cell assembly 12 has 160 fuel cell units 16, and all of these fuel cell units 16 are connected in series.

A combustion chamber 18 is formed above the above-described power generation chamber 10 in the sealed space 8 of the fuel cell module 2. In this combustion chamber 18, the remaining fuel gas that has not been used for the power generation reaction and the remaining oxidant (air) ) And combusted to generate exhaust gas.
Further, a reformer 20 for reforming the fuel gas is disposed above the combustion chamber 18, and the reformer 20 is heated to a temperature at which a reforming reaction can be performed by the combustion heat of the residual gas. ing. Further, an air heat exchanger 22 for receiving combustion heat and heating air is disposed above the reformer 20.

  Next, the auxiliary unit 4 stores a pure water tank 26 that stores water from a water supply source 24 such as tap water and uses the filter to obtain pure water, and a water flow rate that adjusts the flow rate of the water supplied from the water storage tank. An adjustment unit 28 (such as a “water pump” driven by a motor) is provided. The auxiliary unit 4 also includes a gas shut-off valve 32 that shuts off the fuel gas supplied from a fuel supply source 30 such as city gas, a desulfurizer 36 for removing sulfur from the fuel gas, and a flow rate of the fuel gas. A fuel flow rate adjusting unit 38 (such as a “fuel pump” driven by a motor) is provided. Further, the auxiliary unit 4 includes an electromagnetic valve 42 that shuts off air that is an oxidant supplied from the air supply source 40, a reforming air flow rate adjusting unit 44 that adjusts the air flow rate, and a power generation air flow rate adjusting unit 45 (such as an “air blower” driven by a motor), a first heater 46 for heating the reforming air supplied to the reformer 20, and a second for heating the power generating air supplied to the power generation chamber And a heater 48. The first heater 46 and the second heater 48 are provided in order to efficiently raise the temperature at startup, but may be omitted.

Next, a hot water production apparatus 50 to which exhaust gas is supplied is connected to the fuel cell module 2. The hot water production apparatus 50 is supplied with tap water from the water supply source 24, and the tap water is heated by the heat of the exhaust gas and supplied to a hot water storage tank of an external hot water heater (not shown).
The fuel cell module 2 is provided with a control box 52 for controlling the amount of fuel gas supplied and the like.
Furthermore, the fuel cell module 2 is connected to an inverter 54 that is a power extraction unit (power conversion unit) for supplying the power generated by the fuel cell module to the outside.

Next, the internal structure of a solid oxide fuel cell (SOFC) fuel cell module according to an embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a side sectional view showing a solid oxide fuel cell (SOFC) fuel cell module according to an embodiment of the present invention, and FIG. 3 is a sectional view taken along line III-III in FIG.
As shown in FIGS. 2 and 3, in the sealed space 8 in the housing 6 of the fuel cell module 2, as described above, the fuel cell assembly 12, the reformer 20, and the air heat exchange are sequentially performed from below. A vessel 22 is arranged.

  The reformer 20 is provided with a pure water introduction pipe 60 for introducing pure water and a reformed gas introduction pipe 62 for introducing reformed fuel gas and reforming air to the upstream end side thereof. In addition, in the reformer 20, an evaporation unit 20a and a reforming unit 20b are formed in order from the upstream side, and the reforming unit 20b is filled with a reforming catalyst. The fuel gas and air mixed with the steam (pure water) introduced into the reformer 20 are reformed by the reforming catalyst filled in the reformer 20. As the reforming catalyst, a catalyst obtained by imparting nickel to the alumina sphere surface or a catalyst obtained by imparting ruthenium to the alumina sphere surface is appropriately used.

  A fuel gas supply pipe 64 is connected to the downstream end side of the reformer 20, and the fuel gas supply pipe 64 extends downward and further in an manifold 66 formed below the fuel cell assembly 12. It extends horizontally. A plurality of fuel supply holes 64 b are formed in the lower surface of the horizontal portion 64 a of the fuel gas supply pipe 64, and the reformed fuel gas is supplied into the manifold 66 from the fuel supply holes 64 b.

  A lower support plate 68 having a through hole for supporting the fuel cell stack 14 described above is attached above the manifold 66, and the fuel gas in the manifold 66 flows into the fuel cell unit 16. Supplied.

  Next, an air heat exchanger 22 is provided above the reformer 20. The air heat exchanger 22 includes an air aggregation chamber 70 on the upstream side and two air distribution chambers 72 on the downstream side. The air aggregation chamber 70 and the air distribution chamber 72 include six air flow path tubes 74. Connected by. Here, as shown in FIG. 3, three air flow path pipes 74 form a set (74a, 74b, 74c, 74d, 74e, 74f), and the air in the air collecting chamber 70 is in each set. It flows into each air distribution chamber 72 from the air flow path pipe 74.

The air flowing through the six air flow path pipes 74 of the air heat exchanger 22 is preheated by exhaust gas that burns and rises in the combustion chamber 18.
An air introduction pipe 76 is connected to each of the air distribution chambers 72, the air introduction pipe 76 extends downward, and the lower end side communicates with the lower space of the power generation chamber 10, and the air that has been preheated in the power generation chamber 10. Is introduced.

Next, an exhaust gas chamber 78 is formed below the manifold 66. Further, as shown in FIG. 3, an exhaust gas passage 80 extending in the vertical direction is formed inside the front surface 6 a and the rear surface 6 b which are surfaces along the longitudinal direction of the housing 6, and the upper end side of the exhaust gas passage 80 is formed. Is in communication with the space in which the air heat exchanger 22 is disposed, and the lower end side is in communication with the exhaust gas chamber 78. Further, an exhaust gas discharge pipe 82 is connected to substantially the center of the lower surface of the exhaust gas chamber 78, and the downstream end of the exhaust gas discharge pipe 82 is connected to the above-described hot water producing apparatus 50 shown in FIG.
As shown in FIG. 2, an ignition device 83 for starting combustion of fuel gas and air is provided in the combustion chamber 18.

Next, the fuel cell unit 16 will be described with reference to FIG. FIG. 4 is a partial cross-sectional view showing a fuel cell unit of a solid oxide fuel cell (SOFC) according to an embodiment of the present invention.
As shown in FIG. 4, the fuel cell unit 16 includes a fuel cell 84 and inner electrode terminals 86 respectively connected to the vertical ends of the fuel cell 84.
The fuel cell 84 is a tubular structure extending in the vertical direction, and includes a cylindrical inner electrode layer 90 that forms a fuel gas flow path 88 therein, a cylindrical outer electrode layer 92, an inner electrode layer 90, and an outer side. An electrolyte layer 94 is provided between the electrode layer 92 and the electrode layer 92. The inner electrode layer 90 is a fuel electrode through which fuel gas passes and becomes a (−) electrode, while the outer electrode layer 92 is an air electrode in contact with air and becomes a (+) electrode.

  Since the inner electrode terminal 86 attached to the upper end side and the lower end side of the fuel cell 16 has the same structure, the inner electrode terminal 86 attached to the upper end side will be specifically described here. The upper portion 90 a of the inner electrode layer 90 includes an outer peripheral surface 90 b and an upper end surface 90 c exposed to the electrolyte layer 94 and the outer electrode layer 92. The inner electrode terminal 86 is connected to the outer peripheral surface 90b of the inner electrode layer 90 through a conductive sealing material 96, and is further in direct contact with the upper end surface 90c of the inner electrode layer 90, thereby Electrically connected. A fuel gas passage 98 communicating with the fuel gas passage 88 of the inner electrode layer 90 is formed at the center of the inner electrode terminal 86.

  The inner electrode layer 90 includes, for example, a mixture of Ni and zirconia doped with at least one selected from rare earth elements such as Ca, Y, and Sc, and Ni and ceria doped with at least one selected from rare earth elements. The mixture is formed of at least one of Ni and a mixture of lanthanum garade doped with at least one selected from Sr, Mg, Co, Fe, and Cu.

  The electrolyte layer 94 is, for example, zirconia doped with at least one selected from rare earth elements such as Y and Sc, ceria doped with at least one selected from rare earth elements, lanthanum gallate doped with at least one selected from Sr and Mg, Formed from at least one of the following.

  The outer electrode layer 92 includes, for example, lanthanum manganite doped with at least one selected from Sr and Ca, lanthanum ferrite doped with at least one selected from Sr, Co, Ni and Cu, Sr, Fe, Ni and Cu. It is formed from at least one of lanthanum cobaltite doped with at least one selected from the group consisting of silver and silver.

Next, the fuel cell stack 14 will be described with reference to FIG. FIG. 5 is a perspective view showing a fuel cell stack of a solid oxide fuel cell (SOFC) according to an embodiment of the present invention.
As shown in FIG. 5, the fuel cell stack 14 includes 16 fuel cell units 16, and the lower end side and the upper end side of these fuel cell units 16 are a ceramic lower support plate 68 and an upper side, respectively. It is supported by the support plate 100. The lower support plate 68 and the upper support plate 100 are formed with through holes 68a and 100a through which the inner electrode terminal 86 can pass.

  Furthermore, a current collector 102 and an external terminal 104 are attached to the fuel cell unit 16. The current collector 102 includes a fuel electrode connection portion 102a that is electrically connected to an inner electrode terminal 86 attached to the inner electrode layer 90 that is a fuel electrode, and an entire outer peripheral surface of the outer electrode layer 92 that is an air electrode. And an air electrode connecting portion 102b electrically connected to each other. The air electrode connecting portion 102b is formed of a vertical portion 102c extending in the vertical direction on the surface of the outer electrode layer 92 and a plurality of horizontal portions 102d extending in a horizontal direction along the surface of the outer electrode layer 92 from the vertical portion 102c. Has been. The fuel electrode connection portion 102a is linearly directed obliquely upward or obliquely downward from the vertical portion 102c of the air electrode connection portion 102b toward the inner electrode terminal 86 positioned in the vertical direction of the fuel cell unit 16. It extends.

  Further, the inner electrode terminals 86 at the upper end and the lower end of the two fuel cell units 16 located at the ends of the fuel cell stack 14 (the far left side and the near side in FIG. 5) are external terminals, respectively. 104 is connected. These external terminals 104 are connected to the external terminals 104 (not shown) of the fuel cell unit 16 at the end of the adjacent fuel cell stack 14, and as described above, the 160 fuel cell units 16 Everything is connected in series.

Next, sensors and the like attached to the solid oxide fuel cell (SOFC) according to the present embodiment will be described with reference to FIG. FIG. 6 is a block diagram illustrating a solid oxide fuel cell (SOFC) according to an embodiment of the present invention.
As shown in FIG. 6, the solid oxide fuel cell 1 includes a control unit 110, and the control unit 110 includes operation buttons such as “ON” and “OFF” for operation by the user. A device 112, a display device 114 for displaying various data such as a power generation output value (wattage), and a notification device 116 for issuing an alarm (warning) in an abnormal state are connected. The notification device 116 may be connected to a remote management center and notify the management center of an abnormal state.

Next, signals from various sensors described below are input to the control unit 110.
First, the combustible gas detection sensor 120 is for detecting a gas leak, and is attached to the fuel cell module 2 and the auxiliary unit 4.
The CO detection sensor 122 detects whether or not CO in the exhaust gas originally discharged to the outside through the exhaust gas passage 80 or the like leaks to an external housing (not shown) that covers the fuel cell module 2 and the auxiliary unit 4. Is to do.
The hot water storage state detection sensor 124 is for detecting the temperature and amount of hot water in a water heater (not shown).

The power state detection sensor 126 is for detecting the current and voltage of the inverter 54 and the distribution board (not shown).
The power generation air flow rate detection sensor 128 is for detecting the flow rate of power generation air supplied to the power generation chamber 10.
The reforming air flow sensor 130 is for detecting the flow rate of the reforming air supplied to the reformer 20.
The fuel flow sensor 132 is for detecting the flow rate of the fuel gas supplied to the reformer 20.

The water flow rate sensor 134 is for detecting the flow rate of pure water (steam) supplied to the reformer 20.
The water level sensor 136 is for detecting the water level of the pure water tank 26.
The pressure sensor 138 is for detecting the pressure on the upstream side outside the reformer 20.
The exhaust temperature sensor 140 is for detecting the temperature of the exhaust gas flowing into the hot water production apparatus 50.

As shown in FIG. 3, the power generation chamber temperature sensor 142 is provided on the front side and the back side in the vicinity of the fuel cell assembly 12, and detects the temperature in the vicinity of the fuel cell stack 14 to thereby detect the fuel cell stack. 14 (ie, the fuel cell 84 itself) is estimated.
The combustion chamber temperature sensor 144 is for detecting the temperature of the combustion chamber 18.
The exhaust gas chamber temperature sensor 146 is for detecting the temperature of the exhaust gas in the exhaust gas chamber 78.
The reformer inlet temperature sensor 148 is for detecting the inlet temperature of the reformer 20, and the reformer outlet temperature sensor 149 is for detecting the outlet temperature of the reformer 20.
The outside air temperature sensor 150 is for detecting the temperature of the outside air when the solid oxide fuel cell (SOFC) is disposed outdoors. Further, a sensor for measuring the humidity or the like of the outside air may be provided.

Signals from these sensors are sent to the control unit 110, and the control unit 110, based on data based on these signals, the water flow rate adjustment unit 28, the fuel flow rate adjustment unit 38, the reforming air flow rate adjustment unit 44, A control signal is sent to the power generation air flow rate adjusting unit 45 to control each flow rate in these units.
Further, the control unit 110 sends a control signal to the inverter 54 to control the power supply amount.

Next, the operation at the time of start-up by the solid oxide fuel cell (SOFC) according to the present embodiment will be described with reference to FIG. FIG. 7 is a time chart showing the operation at the time of startup of the solid oxide fuel cell (SOFC) according to one embodiment of the present invention.
Initially, in order to warm the fuel cell module 2, the operation is started in a no-load state, that is, in a state where a circuit including the fuel cell module 2 is opened. At this time, since no current flows through the circuit, the fuel cell module 2 does not generate power.

First, reforming air is supplied from the reforming air flow rate adjustment unit 44 to the reformer 20 of the fuel cell module 2 via the first heater 46. At the same time, the power generation air is supplied from the power generation air flow rate adjustment unit 45 to the air heat exchanger 22 of the fuel cell module 2 via the second heater 48, and this power generation air is supplied to the power generation chamber 10 and the combustion chamber. Reach chamber 18.
Immediately after this, the fuel gas is also supplied from the fuel flow rate adjustment unit 38, and the fuel gas mixed with the reforming air passes through the reformer 20, the fuel cell stack 14, and the fuel cell unit 16, and It reaches the combustion chamber 18.

  Next, the ignition device 83 is ignited to burn the fuel gas and air (reforming air and power generation air) in the combustion chamber 18. Exhaust gas is generated by the combustion of the fuel gas and air, and the power generation chamber 10 is warmed by the exhaust gas, and when the exhaust gas rises in the sealed space 8 of the fuel cell module 2, The fuel gas containing the reforming air is warmed, and the power generation air in the air heat exchanger 22 is also warmed.

  At this time, the fuel gas mixed with the reforming air is supplied to the reformer 20 by the fuel flow rate adjusting unit 38 and the reforming air flow rate adjusting unit 44. The partial oxidation reforming reaction POX shown in FIG. Since the partial oxidation reforming reaction POX is an exothermic reaction, the startability is good. Further, the heated fuel gas is supplied to the lower side of the fuel cell stack 14 through the fuel gas supply pipe 64, whereby the fuel cell stack 14 is heated from below, and the combustion chamber 18 also has the fuel gas and air. The fuel cell stack 14 is also heated from above, and as a result, the fuel cell stack 14 can be heated substantially uniformly in the vertical direction. Even if the partial oxidation reforming reaction POX proceeds, the combustion reaction between the fuel gas and air continues in the combustion chamber 18.

_{C m H n + xO 2 →} aCO 2 + bCO + cH 2 (1)

  When the reformer inlet temperature sensor 148 and the reformer outlet temperature sensor 149 detect that the reformer 20 has reached a predetermined temperature (for example, 600 ° C.) after the partial oxidation reforming reaction POX starts, The adjusting unit 28, the fuel flow rate adjusting unit 38, and the reforming air flow rate adjusting unit 44 supply a gas in which fuel gas, reforming air, and water vapor are mixed in advance to the reformer 20. At this time, in the reformer 20, an autothermal reforming reaction ATR in which the partial oxidation reforming reaction POX described above and a steam reforming reaction SR described later are used proceeds. Since the autothermal reforming reaction ATR is thermally balanced internally, the reaction proceeds in the reformer 20 in a thermally independent state. That is, when oxygen (air) is large, heat generation by the partial oxidation reforming reaction POX is dominant, and when there is much steam, an endothermic reaction by the steam reforming reaction SR is dominant. At this stage, the initial stage of startup has already passed, and the temperature inside the power generation chamber 10 has been raised to a certain temperature. Therefore, even if the endothermic reaction is dominant, no significant temperature drop is caused. Further, the combustion reaction continues in the combustion chamber 18 even while the autothermal reforming reaction ATR is in progress.

  When the reformer temperature sensor 146 detects that the reformer 20 has reached a predetermined temperature (for example, 700 ° C.) after the start of the autothermal reforming reaction ATR shown in Formula (2), the reforming air flow rate The supply of reforming air by the adjustment unit 44 is stopped, and the supply of water vapor by the water flow rate adjustment unit 28 is increased. As a result, the reformer 20 is supplied with a gas that does not contain air and contains only fuel gas and water vapor, and the steam reforming reaction SR of formula (3) proceeds in the reformer 20.

_{C m H n + xO 2 +} yH 2 O → aCO 2 + bCO + cH 2 (2)
C _m H _n + xH ₂ O → aCO ₂ + bCO + cH ₂ (3)

  Since the steam reforming reaction SR is an endothermic reaction, the reaction proceeds while maintaining a heat balance with the combustion heat from the combustion chamber 18. At this stage, since the fuel cell module 2 is in the final stage of start-up, the power generation chamber 10 is heated to a sufficiently high temperature. Therefore, even if the endothermic reaction proceeds, the power generation chamber 10 is greatly reduced in temperature. There is nothing. Even if the steam reforming reaction SR proceeds, the combustion reaction continues in the combustion chamber 18.

  In this way, after the fuel cell module 2 is ignited by the ignition device 83, the partial oxidation reforming reaction POX, the autothermal reforming reaction ATR, and the steam reforming reaction SR proceed in sequence, so that the inside of the power generation chamber 10 The temperature gradually increases. Next, when the temperature in the power generation chamber 10 and the fuel cell 84 reaches a predetermined power generation temperature lower than the rated temperature at which the fuel cell module 2 is stably operated, the circuit including the fuel cell module 2 is closed, and the fuel cell Power generation by the module 2 is started, so that a current flows in the circuit. Due to the power generation of the fuel cell module 2, the fuel cell 84 itself also generates heat, and the temperature of the fuel cell 84 also rises. As a result, the rated rated temperature at which the fuel cell module 2 is operated becomes, for example, 600 ° C. to 800 ° C.

  Thereafter, in order to maintain the rated temperature, more fuel gas and air than the amount of fuel gas and air consumed in the fuel cell 84 are supplied, and combustion in the combustion chamber 18 is continued. During power generation, power generation proceeds in a steam reforming reaction SR with high reforming efficiency.

Next, the operation when the solid oxide fuel cell (SOFC) according to the present embodiment is stopped will be described with reference to FIG. FIG. 8 is a time chart showing the operation when the solid oxide fuel cell (SOFC) is stopped according to this embodiment.
As shown in FIG. 8, when the operation of the fuel cell module 2 is stopped, first, the fuel flow rate adjustment unit 38 and the water flow rate adjustment unit 28 are operated to supply fuel gas and water vapor to the reformer 20. Reduce the amount.

  Further, when the operation of the fuel cell module 2 is stopped, the amount of fuel gas and water vapor supplied to the reformer 20 is reduced, and at the same time, the fuel cell module for generating air by the reforming air flow rate adjusting unit 44 The supply amount into 2 is increased, the fuel cell assembly 12 and the reformer 20 are cooled by air, and these temperatures are lowered. Thereafter, when the temperature of the power generation chamber decreases to a predetermined temperature, for example, 400 ° C., the supply of fuel gas and steam to the reformer 20 is stopped, and the steam reforming reaction SR of the reformer 20 is ended. This supply of power generation air continues until the temperature of the reformer 20 decreases to a predetermined temperature, for example, 200 ° C., and when this temperature is reached, the power generation air from the power generation air flow rate adjustment unit 45 is supplied. Stop supplying.

  As described above, in the present embodiment, when the operation of the fuel cell module 2 is stopped, the steam reforming reaction SR by the reformer 20 and the cooling by the power generation air are used in combination. The operation of the fuel cell module can be stopped.

Next, with reference to FIG. 9, the operation at the time of restart of the fuel cell system 1 according to the present embodiment will be described.
The fuel cell system 1 of the present embodiment includes a control mode (normal start mode) for executing the operation at the normal start shown in FIG.
In addition, the fuel cell system 1 according to the present embodiment performs a restart control for restarting an operation when an operation start (that is, restart) is requested during the operation stop operation shown in FIG. It has a mode (restart mode).

FIG. 9 shows an embodiment of the processing flow in the restart mode.
First, when the restart control process flow is started, the control unit 110 acquires the reformer temperature Tr based on the detection signals of the reformer inlet temperature sensor 148 and the reformer outlet temperature sensor 149 ( Step S1). The reformer temperature Tr is, for example, an average temperature of the inlet temperature and the outlet temperature of the reformer 20 calculated based on detection signals from the reformer inlet temperature sensor 148 and the reformer outlet temperature sensor 149.

  Next, the controller 110 determines whether or not the reformer temperature Tr is lower than the steam reforming reaction possible temperature T2 (hereinafter also referred to as “SR possible temperature T2”) (step S2). The SR possible temperature T2 is 350 ° C. or higher, and is usually set within the range of 450 ° C. to 600 ° C.

When the reformer temperature Tr is lower than the SR possible temperature T2 (step S2; Yes), the control unit 110 proceeds to the process of step S4.
On the other hand, when the reformer temperature Tr is not lower than the SR possible temperature T2 (step S2; No), the control unit 110 supplies the power generation air supplied to the fuel cell module 2 by the power generation air flow rate adjustment unit 45. , The reformer 20 is forcibly cooled with air until the reformer temperature Tr becomes lower than the SR possible temperature T2 (step S3), and the process proceeds to step S4.

  In the process of step S4, the control unit 110 starts the restart control of the fuel cell system 1 from the operation control state (POX process) of the partial oxidation reforming reaction POX (step S4), and ends the process. After shifting to the POX process for restarting, the operation control state is changed to the operation control state of the autothermal reforming reaction ATR (ATR process) and the operation control state of the steam reforming reaction SR (SR process) according to predetermined conditions. Can be transferred sequentially.

  In the present embodiment, in the POX process at the time of restart, the amount of fuel gas and reforming air supplied is reduced and the amount of heat generated per unit time is reduced compared to the POX process at the time of normal startup. The control contents are set differently. By reducing the supply amount of fuel gas and / or reforming air, the calorific value per unit time can be reduced. Thereby, it is possible to prevent the overall or local overheating of the reformer 20 or the like due to the accumulation of the residual heat in the fuel cell module 2.

Thus, in this embodiment, at the time of restarting, even if the reformer temperature Tr is equal to or higher than the SR possible temperature T2, starting from the ATR process or SR process is prohibited. In the present embodiment, when the reformer temperature Tr is equal to or higher than the SR possible temperature T2 at the time of restart, the reformer 20 in the high temperature state is forcibly cooled to reduce the reformer temperature Tr to the SR possible temperature T2. After lowering the temperature, start-up control is performed from the POX process.
In the present embodiment, the reformer 20 is forcibly air-cooled in the process of step S3. However, the present invention is not limited to this, and the reformer 20 is not forcedly air-cooled, but by a normal operation stop operation or natural cooling. It may be configured to wait for cooling.

  With this configuration, in this embodiment, the restart control is started from the POX process at the time of restart, so that the water and fuel supply timing control in the ATR process and the SR process is precisely performed as in the past. Since it is not necessary, the control can be simplified and the occurrence of problems such as carbon deposition and catalyst deterioration due to the difficulty in controlling the supply timing of water and fuel in the ATR process and SR process can be avoided. .

Next, with reference to FIG. 10, the operation | movement at the time of restart of the fuel cell system 1 by other embodiment is demonstrated.
FIG. 10 shows a processing flow of restart control executed in place of FIG.
First, when the restart control process flow is started, the control unit 110 acquires the reformer inlet temperature Tr1 based on the detection signal from the reformer inlet temperature sensor 148 (step S11).

Next, the controller 110 determines whether or not the reformer inlet temperature Tr1 is lower than a predetermined temperature (200 ° C. in this example) (step S12). The predetermined temperature is a temperature set at 100 ° C. or more lower than the SR possible temperature T2.
Since the temperature distribution in the fuel cell module 2 varies, there is a possibility that any specific part of the reformer 20 is locally hotter than the measurement part. For this reason, at the start of the restart control, even if the reformer inlet temperature Tr1 is lower than the SR possible temperature T2, there is a possibility that the specific part in the reformer 20 is equal to or higher than the SR possible temperature T2. .

  Therefore, in the present embodiment, in consideration of variations in temperature distribution in the fuel cell module 2 and the reformer 20, the predetermined temperature is the reformer inlet temperature Tr1 during the shutdown operation. Sometimes, all the parts in the reformer 20 are set to be lower than the SR possible temperature T2. In this embodiment, when the reformer inlet temperature Tr1 is 100 ° C. or more lower than the SR possible temperature T2, it is confirmed that all the parts in the reformer 20 are surely lower than the SR possible temperature T2. .

When the reformer inlet temperature Tr1 is lower than the predetermined temperature (step S12; Yes), the control unit 110 proceeds to the process of step S14.
On the other hand, when the reformer inlet temperature Tr1 is not lower than the predetermined temperature (step S12; No), the control unit 110 determines the amount of power generation air supplied by the power generation air flow rate adjustment unit 45 into the fuel cell module 2. By increasing the temperature, the reformer 20 is forcibly cooled with air until the reformer inlet temperature Tr1 becomes lower than a predetermined temperature (step S13), and the process proceeds to step S14.

  In the process of step S14, the control unit 110 starts the restart control of the fuel cell system 1 from the POX process (step S14). However, the POX process started in step S14 is a preliminary or restrictive POX process (hereinafter referred to as “restrictive POX process”) before starting the full-scale POX process. In the present embodiment, the supply amount of the fuel gas and reforming air necessary for performing the partial oxidation reforming reaction POX is set to be smaller than that in the subsequent POX process (step S17) in this restrictive POX process. ing.

  The fuel cell module 2 accumulates a large amount of residual heat at the time of restarting from the operation stop operation compared to the case of starting from normal temperature. That is, even if the reformer inlet temperature Tr1 is lower than the predetermined temperature in steps S12 and S13, the fuel cell module 2 including the reformer 20 accumulates a large amount of residual heat inside. Therefore, at the time of the process of step S14, when starting from the normal or near POX process, the reformer 20 or the like may be excessively heated and deteriorate.

  For this reason, in the present embodiment, instead of starting a POX process that is normal or close to that from the beginning, in order to initially suppress the exothermic reaction due to the partial oxidation reforming reaction POX, by executing the restrictive POX process, The supply amount of fuel gas and reforming air is limited to a small amount. By the restrictive POX process using the small amount of fuel gas and reforming air, the reformer 20 is gradually heated by the reaction heat of POX and the combustion heat of the fuel gas.

  Next, the control unit 110 acquires the reformer outlet temperature Tr2 based on the detection signal from the reformer outlet temperature sensor 149 (step S15), and the reformer outlet temperature Tr2 is set to a second predetermined temperature (the main temperature). In the example, it is determined whether the temperature is 250 ° C. or higher (step S16).

  When the reformer outlet temperature Tr2 is not equal to or higher than the second predetermined temperature (step S16; No), the control unit 110 repeats the process of step S15 and calculates the reformer outlet temperature Tr2. In this way, the control unit 110 repeats the processes of steps S15 and S16 until the reformer outlet temperature Tr2 becomes equal to or higher than the second predetermined temperature (step S16; Yes).

  When the reformer outlet temperature Tr2 becomes equal to or higher than the second predetermined temperature (step S16; Yes), the control unit 110 shifts from the restrictive POX process to the full-scale restart POX process, In accordance with the POX process, the supply amounts of the fuel gas and the reforming air are increased, and the process proceeds to the restarting POX process (step S17), and the process ends. After shifting to the POX process for restarting, it is possible to shift to the ATR process and the SR process sequentially according to predetermined conditions.

  Although the temperature of the reformer 20 gradually increases as a whole by the above-described restrictive POX process, in this embodiment, if the outlet temperature Tr2 of the reformer 20 rises to a second predetermined temperature or higher. Since it is possible to confirm that the temperature rise due to the combustion flame has spread throughout and the temperature of the reformer 20 has been raised to the second predetermined temperature or higher as a whole, the reformer outlet temperature Tr2 is equal to or higher than the second predetermined temperature. Until the temperature rises, the local excessive temperature rise can be more reliably suppressed by reducing the amount of fuel gas and the amount of reforming air.

  As described above, in the present embodiment, at the time of restart, the entire reformer 20 is surely cooled to the SR possible temperature T2 or lower, and then the reformer 20 is gradually heated by the restrictive POX process. Thus, the temperature of the entire reformer 20 is increased, and when the temperature is sufficiently increased, the fuel gas and the reforming air are increased and the POX process is executed in earnest. This avoids the occurrence of problems such as carbon deposition and catalyst deterioration due to the difficulty in controlling the supply timing of water and fuel in the ATR process and SR process, and increases the excessive temperature rise of the reformer 20 in the temperature raising process. Can be prevented.

Next, each operation control state in the normal start mode and the restart mode will be described with reference to FIG.
First, the normal activation mode will be described. As shown in FIG. 11, in the normal startup mode, the control unit 110 sequentially executes each operation control state (ignition process, combustion operation process, normal startup POX process, normal startup ATR process, normal startup SR process) in time order. It is configured as follows. The time change of parameters such as the reformer temperature in the normal startup mode is as described with reference to FIG.

  First, in the ignition process, the fuel gas supply amount by the fuel flow rate adjustment unit 38 is 6.0 (L / min), and the reforming air supply amount by the reforming air flow rate adjustment unit 44 is 10.0 (L / min). min), the supply amount of power generation air by the power generation air flow rate adjustment unit 45 is set to 100.0 (L / min), and the supply amount of water by the water flow rate adjustment unit 28 is set to 0.0 (cc / min). .

  In this state, in the ignition process, the fuel gas is ignited by the ignition device 83, and the process proceeds to the combustion operation process (heating process). In the combustion operation process, the fuel gas supply amount, the reforming air supply amount, the power generation air supply amount, and the water supply amount are the same as those in the ignition process, and the reformer 20 is heated by the combustion heat of the fuel gas. To do.

  When the reformer temperature Tr becomes equal to or higher than 300 ° C., which is the partial oxidation reforming reaction start temperature T1, during the combustion operation process, the control unit 110 shifts the operation control state to the normal startup POX process. At this time, the supply amount of the fuel gas is reduced to 5.0 (L / min), the supply amount of the reforming air is increased to 18.0 (L / min), and the partial oxidation reforming reaction POX of the fuel gas is performed. The reformer 20 is heated by the reaction heat and the combustion heat of the combustion gas.

  Next, during the normal startup POX process, the reformer temperature Tr becomes 600 ° C., which is the steam reforming reaction possible temperature T2 (SR possible temperature T2), and the fuel cell measured by the power generation chamber temperature sensor 142 When the stack temperature Ts, which is the temperature near the stack 14 (that is, the fuel cell 84 itself) becomes 250 ° C. or higher, the control unit 110 shifts the operation control state from the normal startup POX process to the normal startup ATR process. At this time, the fuel gas supply amount is reduced to 4.0 (L / min), the reforming air supply amount is further reduced to 4.0 (L / min), and the water supply amount is 3.0 (L / min). cc / min) and the autothermal reforming reaction ATR is performed. In the autothermal reforming reaction ATR, the partial oxidation reforming reaction POX and the steam reforming reaction SR are used together, the reaction heat of the partial oxidation reforming reaction POX of the fuel gas, the combustion heat of the fuel gas, and the steam of the fuel gas The reformer 20 is heated by controlling the endothermic reaction of the reforming reaction SR.

Next, when the reformer temperature Tr becomes 650 ° C. or higher and the stack temperature Ts becomes 600 ° C. or higher during the normal startup ATR process, the control unit 110 changes the operation control state from the normal startup ATR process to the normal startup SR. Move to the process. At this time, the fuel gas supply amount is further reduced to 3.0 (L / min), the reforming air supply amount is reduced to 0.0 (L / min), and the water supply amount is 8.0 (L / min). cc / min), and the steam reforming reaction SR is performed.
Thereafter, when the reformer temperature Tr becomes 650 ° C. or higher and the stack temperature Ts becomes 700 ° C. or higher during the normal startup SR process, the control unit 110 ends the normal startup SR process and thereby starts normal startup. Exit the mode and enter normal operation mode.

  Next, the restart mode will be described. As shown in FIG. 11, in the restart mode, the control unit 110 sequentially executes each operation control state (ignition process, restart POX process, normal start ATR process, normal start SR process) in time order as necessary. It is configured as follows.

First, in the ignition step, the fuel gas supply amount, the reforming air supply amount, the power generation air supply amount, and the water supply amount are set to be the same as those in the normal startup mode ignition step.
In this state, the fuel gas is ignited by the ignition device 83 in the ignition process. However, in the restart mode, the control unit 110 performs ignition after waiting until the reformer temperature Tr becomes a temperature lower than the SR possible temperature T2 (200 ° C. or less in this example), and restarts after ignition. Move to POX process. In the example of FIG. 10, the reformer temperature Tr1 is used as the reformer temperature Tr.

In the restart POX process, the supply amount of fuel gas is reduced to 4.5 (L / min), the supply amount of reforming air is increased to 17.0 (L / min), and partial oxidation reforming of the fuel gas is performed. The reformer 20 is heated by the reaction heat of the quality reaction POX and the combustion heat of the combustion gas.
In the present embodiment, the contents of control are different in the restart POX process so that the supply amount of the fuel gas and the reforming air is reduced and the calorific value per time is reduced compared to the normal startup POX process. Is set. Thereby, it is possible to prevent an excessive temperature rise of the reformer 20 and the like due to the accumulation of residual heat in the fuel cell module 2.

  Similarly to the example of FIG. 10, the restrictive POX process is executed before the restart POX process, and the reformer outlet temperature Tr2 becomes equal to or higher than the second predetermined temperature (250 ° C.). Alternatively, it may be configured to shift to the restart POX process.

  Next, when the reformer temperature Tr becomes 500 ° C. or higher during the restart POX process, the control unit 110 shifts the operation control state from the restart POX process to the normal start ATR process. At this time, the fuel gas supply amount is reduced to 4.0 (L / min), the reforming air supply amount is reduced to 4.0 (L / min), and the water supply amount is 3.0 (cc). / min) and the autothermal reforming reaction ATR is performed. Note that the supply amount of fuel gas, the supply amount of reforming air, the supply amount of power generation air, and the supply amount of water at this time are set to be the same as the normal startup ATR in the normal startup mode.

  In the restart POX process of this embodiment, when the reformer temperature Tr reaches 500 ° C. or higher, the operation control state is configured to switch to the normal start ATR process, and the normal start from the normal start POX process in the normal start mode. It is set lower than the temperature condition (600 ° C.) for switching to the ATR process. That is, the switching temperature of the reformer temperature Tr is 600 ° C. in the normal startup mode, while it is reduced to 500 ° C. in the restart mode. As a result, the restart POX process has a shorter execution time than the normal start POX process. In the restart mode, the partial oxidation reforming reaction POX, which is an exothermic reaction, is completed in a short time, and the next autothermal reforming process is performed. By shifting to the quality reaction ATR, excessive temperature rise can be prevented.

  Next, when the reformer temperature Tr becomes 600 ° C. or higher and the stack temperature Ts becomes 600 ° C. or higher during the normal startup ATR process in the restart mode, the control unit 110 changes the operation control state to the normal startup ATR. The process proceeds from the process to the normal startup SR process. At this time, the fuel gas supply amount is further reduced to 3.0 (L / min), the reforming air supply amount is reduced to 0.0 (L / min), and the water supply amount is 8.0 (L / min). cc / min), and the steam reforming reaction SR is performed. At this time, the supply amount of fuel gas, the supply amount of reforming air, the supply amount of power generation air, and the supply amount of water are set to be the same as the normal startup SR in the normal startup mode.

  In the present embodiment, the reformer temperature Tr as a condition for shifting from the normal startup ATR process in the restart mode to the normal startup SR process is 600 ° C., which is higher than that in the normal startup mode (650 ° C.). Is set too low. At the time of restart, since the residual heat is accumulated in the fuel cell module 2 as described above, in the present embodiment, the reformer temperature Tr becomes 600 ° C. or higher, which is a temperature lower than 650 ° C. in the restart mode. This makes it possible to move to the normal startup SR process at an early stage.

  Thereafter, when the reformer temperature Tr becomes 650 ° C. or higher during the normal startup SR process in the restart mode (and the stack temperature Ts becomes 700 ° C. or higher), the control unit 110 performs the normal startup mode, that is, the normal startup SR process. To end the normal operation mode.

1 Solid electrolyte fuel cell (fuel cell system)
2 Fuel cell module 4 Auxiliary unit 10 Power generation chamber 12 Fuel cell assembly 14 Fuel cell stack 16 Fuel cell unit 18 Combustion chamber 20 Reformer 22 Air heat exchanger 28 Water flow rate adjustment unit 38 Fuel flow rate adjustment unit 44 reforming air flow rate adjustment unit 45 power generation air flow rate adjustment unit 54 inverter 83 ignition device 84 fuel cell 110 controller

Claims (7)

A fuel cell system comprising a reformer for supplying a reformed fuel gas to a fuel cell and a control means,
In the start-up control of the fuel cell system, the control means (1) heats the reformer with heat of combustion caused by fuel gas when the temperature of the reformer is lower than a partial oxidation reforming reaction start temperature (T1). (2) When the temperature of the reformer is equal to or higher than the partial oxidation reforming reaction start temperature (T1) and lower than the steam reforming reaction possible temperature (T2), the partial oxidation reforming reaction of the fuel gas is performed. A POX process in which the reformer is heated by reaction heat and combustion heat from the combustion gas; and (3) partial oxidation reforming of the fuel gas when the temperature of the reformer is equal to or higher than the steam reforming reaction temperature (T2). Autothermal reforming reaction, which combines the quality reaction and steam reforming reaction, to control the reaction heat of partial oxidation reforming reaction of fuel gas, combustion heat by fuel gas, and endotherm of steam reforming reaction of fuel gas And an ATR process for heating the reformer, It is configured to execute,
If the temperature of the reformer at the time of starting the start control of the fuel cell system is equal to or higher than the steam reforming reaction possible temperature (T2), the control means does not start the start control from the ATR step. The fuel cell system is characterized in that the POX step is executed after the temperature of the reformer has dropped below a steam reforming reaction possible temperature (T2).   The control means performs the POX process after the temperature of the reformer is lowered to a temperature lower than the steam reforming reaction possible temperature (T2), and the temperature of the reformer is lower than the partial oxidation reforming reaction start temperature (T1). 2. The fuel cell system according to claim 1, wherein the control content is executed differently from the POX process in the normal start-up control started from the state.   The control means performs a POX process performed after the temperature of the reformer has decreased below the steam reforming reaction possible temperature (T2) so that the amount of heat generated per hour is smaller than that of the POX process in the normal start-up control. The fuel cell system according to claim 2, wherein the fuel cell system is controlled.   The control means is configured to make the POX process performed after the temperature of the reformer lowers below the steam reforming reaction possible temperature (T2) to be shorter than the POX process in the normal start-up control. The fuel cell system according to claim 2.   The control means is configured not to start the POX process until the temperature of the reformer decreases to a predetermined temperature lower than the steam reforming reaction possible temperature (T2). The fuel cell system according to claim 2.   6. The steam reforming reaction possible temperature (T2) is 350 ° C. or higher, and the predetermined temperature is set to be 100 ° C. lower than the steam reforming reaction possible temperature (T2). Fuel cell system.   The control means obtains the inlet temperature and the outlet temperature of the reformer, respectively, transitions to the POX process after the inlet temperature is lowered to the predetermined temperature, and a second predetermined temperature at which the outlet temperature is higher than the predetermined temperature. 7. The fuel cell system according to claim 6, wherein the fuel cell system is configured to increase a supply amount of fuel gas and air in the POX process when the temperature becomes higher than a temperature.

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