JP2009146647A - Solid oxide fuel battery power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a startup time, reduce startup energy, and reduce power consumption when rated power is generated. <P>SOLUTION: The solid oxide fuel battery power generation system is provided with a fuel battery, a startup burner to raise a fuel battery temperature, a detection means to detect the fuel battery temperature and a current, and a system control device to produce a signal to stop the startup burner based on a signal from the detection means. This system structure stops the combustion of the startup burner when the system detects that the fuel battery temperature and the current exceed thresholds. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the solid oxide fuel cell power generation system, the present invention is a system that can achieve both shortening of startup time, reduction of startup energy, and reduction of power consumption during rated operation.

  A fuel cell includes an anode and a cathode on both sides of an electrolyte, fuel gas is supplied to the anode side, and oxidant gas (mainly air) is supplied to the cathode side, and the fuel and oxidant are electrochemically passed through the electrolyte. It is a power generation device that generates power by reacting. Solid oxide fuel cells, one of the types of fuel cells, have a high operating temperature of about 700-1000 ° C, high power generation efficiency, and easy use of exhaust heat, and are therefore eagerly studied worldwide. It is being advanced.

  Normally, a solid oxide fuel cell constitutes an assembly (module) in which several tens to several hundreds of cells are stacked in order to obtain a desired electric output. Usually, this module raises the temperature to a predetermined temperature (for example, about 600 ° C.) that can be generated by an external heat source such as a burner or a heater, and then generates power. However, it takes time to raise the temperature to this temperature, and there is a problem that the solid oxide fuel cell power generation system is not easy to use because of a large energy loss.

  Moreover, at the time of rated power generation, it is necessary to reduce the power consumption of the system equipment as much as possible for higher efficiency. That is, it is desired for a solid oxide fuel cell power generation system to achieve both shortening of start-up time / start-up energy and power consumption during rated operation.

  As a conventional example for reducing power consumption in a system, an example in which a fuel gas main booster and an auxiliary booster are provided in parallel, and the auxiliary booster is started according to the flow rate of the fuel gas, as shown in Patent Document 1. is there.

  However, in the above invention, only the start / stop of the auxiliary booster is determined based on the flow rate of the fuel gas, and the timing at which the start burner is turned off is not always clear, and the start energy loss is increased accordingly. There wasn't.

JP 2007-128666 A

  The problem to be solved by the present invention is to achieve both shortening of startup time and reduction of startup energy and reduction of power consumption during rated operation.

  The present invention relates to a fuel cell, a starting burner for raising the temperature of the fuel cell, a detecting means for detecting the fuel cell temperature and the fuel cell current or voltage, and the starting burner based on a signal from the detecting means. The present invention relates to a solid oxide fuel cell system including a system control device that generates a stop signal. That is, it is detected that the fuel cell temperature and the fuel cell current exceed a certain threshold in a system that raises the temperature of the fuel cell by combining heat transfer by the combustion gas supply of the start burner and self-heating by the power generation of the fuel cell. Thus, the main feature is to stop the combustion of the start burner. Further, the present invention is characterized in that the control power source for controlling the starting gas line and the control power source for controlling the power generation gas line are separately configured. Furthermore, the present invention is characterized in that the control power source for controlling the starting gas line is stopped after the combustion of the starting burner is stopped.

  Advantageous Effects of Invention According to the present invention, there are advantages that a solid oxide fuel cell or a solid oxide fuel cell system can be shortened in start-up time, reduced in start-up energy, and reduced in power consumption during rated power generation.

  According to an embodiment of the present invention, the control device is a solid oxide fuel cell system including a first control device that controls a startup gas line and a second control device that controls a power generation gas line. Provided. Furthermore, the present invention includes a solid oxide fuel cell system that stops a control power source that controls the starting gas line after the combustion of the starting burner is stopped. Thereby, not only the energy loss at the time of starting can be reduced, but also the power consumption of the fuel cell system shifted to the rated power generation can be reduced and the power generation efficiency can be improved.

  The present invention also includes a module composed of a plurality of solid oxide fuel cells, an air header disposed on the upper portion of the module, means for supplying power generation air to the air header, the air header and the activation burner. A start-up fuel line and start-up air line connected to each other, a sensor for detecting the temperature and current of the solid oxide fuel cell of the module, and a stop signal to the start-up burner based on the signal of the sensor A solid oxide fuel cell system comprising a system controller for transmitting is provided. By detecting the temperature and current value of the fuel cell after start-up operation and controlling the amount of anode gas and cathode gas based on the signal, the fuel cell becomes abnormally hot and is damaged, or wasteful fuel gas and It can prevent that air is supplied.

  In this specification, the “upper part” does not necessarily have a structural meaning, and the preheater is located upstream of the air header to which the cathode gas is supplied, or the air header is closer to the starter burner than the module. This means that it is located upstream.

  Furthermore, a module composed of a plurality of solid oxide fuel cells, an air header disposed on the upper part of the module, a preheater for preheating the power generation air supplied to the air header, and a power generator for the air header. Means for supplying air; a starting burner for supplying combustion gas to the air header; a starting fuel line and a starting air line connected to the air header and the starting burner; and a solid oxide fuel for the module A sensor that detects the temperature and current or voltage of the battery cell, a system control device that transmits a stop signal to the activation burner based on the signal of the sensor, and the activation device based on the control signal of the system control device Solid oxide fuel comprising a first control device for controlling a burner and a second control device for controlling the preheater based on a control signal of the system control device To provide a battery system.

  According to still another embodiment of the present invention, a module composed of a plurality of solid oxide fuel cells, an air header disposed on the module, and preheating for preheating power generation air supplied to the air header. , A means for supplying power generation air to the air header, a start burner for supplying combustion gas to the air header, a start fuel line and a start air line connected to the air header and the start burner And a sensor that detects the temperature and current or voltage of the solid oxide fuel cell of the module, and a system control device that transmits a stop signal to the activation burner based on the signal of the sensor, and the activation When the module temperature Tc and the module temperature increase rate ΔTh satisfy the condition I of Tc> Tmin and ΔTh1 <ΔTh <ΔThmax after the burner is ignited Step I for increasing the amount of air supplied to the air header and the amount of anode gas supplied to the module, starting power generation, and adjusting the combustion amount of the starting burner when the condition I is not satisfied (where Tmin is There is provided a solid oxide fuel cell system including a module temperature necessary for power generation, ΔTh1 is a minimum value of a module heating rate to be controlled, and ΔThmax is a module temperature threshold for preventing damage of the fuel cell) .

After the power generation is started, the system is configured such that when the condition II of Ta>Tc> Tmin, ΔTh1 <ΔTh <ΔThmax, Vc> V ₀ is satisfied, the amount of anode gas supplied to the module and the cathode air supplied to the air header Increase the amount to increase the generated current, decrease the combustion amount of the starting burner, and maintain the generated current at a predetermined value when the above condition II is not satisfied (where Ta is the starting burner Preferably, the module temperature threshold that can be stopped, V _0, is the module voltage required to generate electricity).

Further, when the condition II is satisfied, the system increases the amount of generated current and reduces the combustion amount of the start burner, so that the conditions of Tmax>Tc> Ta, Vc> V ₀ , I> Ia When III is satisfied, the starting burner is stopped and the process proceeds to rated power generation. When the condition III is not satisfied, the anode gas amount for the module is increased, and the cathode air amount for the air header is increased. (Where Tmax is the maximum module limit temperature, I is the generated current, and Ia is the module current threshold at which the start burner can be stopped). In the embodiment of the present invention, after the starting burner is stopped in the step III, the anode gas flow rate and the cathode gas flow rate can be increased to shift to rated power generation.

  The most preferred embodiment of the present invention is a solid oxide fuel cell system that executes from start-up to rated power generation in the order of step I, step II and step III. In this case, after stopping the starting burner in the step III, the anode gas flow rate and the cathode gas flow rate can be increased to shift to rated power generation.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  2, 3 and 4 show a solid oxide fuel cell system according to an embodiment of the present invention. As shown in FIG. 4 as an enlarged cross-sectional view, the solid oxide fuel cell 80 in FIG. 3 includes an anode 80a on the outside of the cylinder, a cathode 80c on the inside, and a solid oxide electrolyte 80e sandwiched between them. Become. Although only 36 solid oxide fuel cells 80 are shown in FIG. 3 for the sake of convenience, power generation is usually performed by stacking and gathering about several tens to several hundreds in series or in parallel. In this specification, this aggregate is referred to as a module 30.

  FIG. 2 is a schematic diagram in which the module 30 is incorporated in a system according to an embodiment of the present invention. An oxidant gas (air or combustion gas) is allowed to flow as the cathode gas 90 on the cathode side of the fuel cell 80. This gas is supplied from the gas supply port, passes through the air header 91 for evenly distributing the gas to each cell, passes through the air introduction pipe 92, and reaches the cathode 80c.

  As a starting procedure, the starting burner 600 is ignited and the starting fuel line 90a and the starting air line 90b are supplied to the starting burner 1 up to about 600 to 700 ° C. which is the lowest temperature at which power generation can be started. It is necessary to continue heating the module with this high-temperature gas.

  Thereafter, when the temperature sensor detects that the module has reached a temperature at which power generation can be started, the startup fuel line 90a is stopped, the startup burner 1 is stopped, and the anode gas 100 and the cathode gas (air) 90 are solid-oxidized. The fuel cell 80 is supplied to generate power. The anode gas 100 is usually supplied as the anode gas 100 after partially or completely steam reforming a gas obtained by mixing a city gas, a hydrocarbon fuel such as LNG or LPG, and steam with a reformer. At the time of power generation, the cell 80 generates heat, so that the cell 80 is operated thermally independently at about 700 to 1000 ° C. with the heat.

  The problem here is the timing of stopping the start burner 600. If the stop is too early, the temperature of the cell is lowered without becoming independent of heat, and the burner needs to be restarted. In this situation, a heat cycle such as a decrease in cell temperature and an increase in cell temperature at the time of restart is applied to the cell, which may lead to cell damage. In addition, if the stop is too slow, there is a problem that the cell and the module are excessively heated to cause material deterioration, and the heat energy loss increases because the starter burner that is originally unnecessary is continuously burned. Therefore, in practice, the detection of the predetermined temperature of the module and the stop of the activation burner based on the signal need to be performed within as short a time as possible (for example, within a few seconds to a few minutes). The time is determined by the heat capacity of the module, the heat capacity of the start burner, the amount of fuel gas, and the like.

  Here, the determination of only the flow rate shown in Patent Document 1 is not suitable for the above-described module thermal independence determination and cell temperature optimal determination, and the timing for stopping the activation burner is not optimized. Further, in the technique described in Patent Document 1, a control power source for controlling the starting gas line, a blower for supplying gas, a flow regulator, a solenoid valve, etc. are provided even after the starting burner is stopped. Since the system continues to operate, standby power is generated, resulting in an increase in power consumption during rated power generation.

  This problem is solved as follows by the system according to the embodiment of the present invention shown in FIG. 2 and the flowchart of FIG. First, the air header 91 in FIG. 2 has two supply ports, a supply port to which a high-temperature gas 90 for activation is supplied and a supply port to which a gas 90c for power generation is supplied, and a gas supply line for activation. And the gas supply line for power generation are separated. Further, the temperature of the module is detected by a temperature sensor 2A provided in the module, and is transmitted to the system control apparatus 300 as a detection signal 2AS for control.

In FIG. 1, Tmin is a module temperature required for power generation, Tmax is a maximum limit temperature of the module, Ta is a module temperature threshold at which the start burner can be stopped, and ΔThmax prevents damage to the fuel cell. Module temperature threshold, ΔTh1 is the minimum module heating rate to be controlled, V ₀ is a module voltage required for power generation, and Ia is a module current threshold at which the start burner can be stopped.

  As a starting procedure, air is sent from the starting air line 90b to the starting burner 600 by the control signal 302S to the starting line, and subsequently, fuel gas is sent from the starting fuel gas line 90a, and at the same time an igniter (not shown). The starting burner 600 is ignited. The high-temperature combustion gas after ignition passes through the air header 91 as 90, is supplied into the module 30, and the temperature rise starts.

  When the temperature rise starts, the module temperature is detected by the temperature sensor 2A in order to prevent damage to the module due to a sudden thermal shock, 2AS is input as a signal to the system controller 300, and the control signal 302S is sent to the start line 90a, The combustion amount of the starting burner is adjusted so as to keep the temperature rising rate transmitted to 90b.

  A temperature rise characteristic diagram in this system configuration is shown in FIG. The hot gas 90 as the module heating means is generated by supplying the burner 600 with the start fuel line 90a and the start air line 90b and combusting it, and supplying it to the nearest cell, thereby increasing the temperature of the module. It becomes easy, and shortening of starting time and starting energy can be achieved.

  In this system, when the temperature starts to rise and the temperature of the module becomes equal to or higher than the power generation start temperature Tmin (for example, 600 ° C.) by the startup gas 90, air is supplied from the power generation air line 90c to the cathode side while burning the startup burner 600. Supply. Then, the system control device 300 activates the load control device 400 by the control signal 303S, draws current from the module by the control signal 304S, and starts power generation. Then, the temperature rise of the module temperature 2A is accelerated by the self-heating of the cell caused by the generated current. Here, by separating the startup gas supply line and the power generation gas supply line, it is possible to adjust the combustion amount of the startup burner and the amount of air necessary for power generation simultaneously and independently. The invention can be activated. In addition, since the preheater 500 that exchanges heat with the exhaust gas 101 is provided, the air line 90c that is supplied when generating power can be supplied to the module in a preheated state, so that the module temperature may suddenly drop at the start of power generation. There is also an advantage of not being.

  Here, conventionally, the timing of stopping the burner 600 is not always clear. Even if the module temperature is low during the temperature rise, the starter burner 600 can be stopped if the amount of self-heating generated by the current can be ensured if the minimum temperature and voltage can be generated even if the module temperature is low. . However, if only the module temperature is set as the threshold value, it cannot be determined, and as a result, the combustion time of the start burner 600 increases, leading to an increase in start-up energy loss. In addition, there is a concern that the module is excessively heated at the threshold value of only current and causes material deterioration.

  On the other hand, in the present invention, as shown in the flowchart of FIG. 1, when the module temperature detected by the temperature sensor 2A exceeds the threshold value Tmin = 850 ° C. and the current also exceeds the threshold value Ia = 20A, the starting burner 600 Since the determination criteria for both the temperature and the current are set such that the start burner 600 is stopped, the stop timing of the start burner 600 is optimized. Here, a measure is taken to reduce the combustion amount of the start burner so that the maximum module temperature Tmax (eg, 950 ° C.) is not reached before the current threshold value Ia = 20 A is reached. As shown in the present invention, such a startup method is achieved by separating the startup gas supply line and the power generation gas supply line, thereby adjusting the combustion amount of the startup burner and the amount of air necessary for power generation. This can be achieved because adjustments can be made independently and simultaneously.

  Further, as shown in the flowchart of FIG. 1, if not only the temperature of the module but also the voltage of the module is monitored, it is possible to start up with less damage to the module. Here, Tmax = 950 ° C., Ta = 850 ° C., Tmin = 600 ° C., and Ia = 20A are merely examples, and there are optimum values depending on the fuel cell material, electrode area, number of cells, module scale, and the like. Needless to say. The most significant feature of the present invention is that both the temperature and the current value or the voltage value, or three of them are used as criteria for determination, and various changes and additions can be made within the spirit.

  FIG. 6 shows another embodiment of the present invention. In this embodiment, the system controller 300 is divided into a power generation line controller 301 and a startup line controller 302. In the present invention, first, the activation burner 1 described in the first embodiment is stopped by a control signal 302 from the activation line control device 302. Thereafter, the activation line control device 301 is turned off by a control signal 302A from the system control device 300. In addition, the power sources of devices such as a blower for the start burner 1, a flow rate regulator, and a solenoid valve are also turned off. By performing such control, the power of all the constituent devices and control devices of the start line, which is unnecessary after the burner is stopped, is turned off, so that standby power is greatly reduced. As a result, power consumption during rated power generation can be reduced, and high efficiency of the fuel cell power generation system can be achieved.

  In the embodiments described so far, a cylindrical shape is shown, but the present invention can be applied to a flat solid oxide fuel cell other than a cylindrical shape. In addition, although the control method of the start burner in the cathode side gas supply line has been described, it goes without saying that the same effect can be obtained with the same configuration on the anode side.

  According to the above-described embodiment of the present invention, the solid oxide fuel cell system can be used as a distributed power supply system that is friendly to the global environment because it can achieve both shortening of startup time, reduction of startup energy, and reduction of power consumption during rated power generation. .

It is a flowchart which shows the starting procedure of Example 1 of this invention. It is a system configuration figure of Example 1 of the present invention. It is a plane sectional view of the module along the AA line of Drawing 2 by Example 1 of the present invention. It is an expansion longitudinal cross-sectional view of the single cell in Example 1 of this invention. It is a temperature increase characteristic figure of the system employ | adopted in Example 1 of this invention. It is a system block diagram by the other Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Startup burner, 2A ... Temperature sensor, 2AS ... Detection signal, 30 ... Module, 80 ... Solid oxide fuel cell, 80a ... Anode, 80c ... Cathode, 80e ... Solid electrolyte, 90 ... Cathode gas, 90a ... Fuel gas line for start-up, 90b ... Air line for start-up, 90c ... Air line for power generation, 91 ... Air header, 92 ... Air introduction pipe, 93 ... Gas supply port, 100 ... Anode gas, 101 ... Exhaust gas, 300 ... System control 301, power generation line control device, 302 ... start line control device, 301S ... control signal to power generation line, 301A ... control signal to power generation line control device, 302S ... control signal to start line, 302A ... Control signal to start line, 303S ... Control signal to load control device, 304S ... Control signal for module generated current 400 ... load controller, 500 ... preheater 600 ... startup burner.

Claims (11)

  A fuel cell; a starting burner for raising the temperature of the fuel cell; a detecting means for detecting the fuel cell temperature and the fuel cell current; and based on a signal from the detecting means, the fuel cell temperature and the fuel cell current or A solid oxide fuel cell system comprising: a system controller that determines that the voltage has reached or exceeded a predetermined threshold and generates a stop signal of the start burner.   2. The solid oxide fuel cell according to claim 1, wherein the control device includes a first control device that controls a start-up gas line and a second control device that controls a power generation gas line. 3. system.   3. The solid oxide fuel cell system according to claim 1, wherein the control power source for controlling the starting gas line is stopped after the combustion of the starting burner is stopped.   A fuel cell module comprising a plurality of solid oxide fuel cells, an air header disposed on the upper portion of the fuel cell module, means for supplying power generation air to the air header, and the air header and starter burner System control for transmitting a stop signal to the start burner based on the connected start fuel line and start air line, a sensor for detecting the temperature and current or voltage of the fuel cell module, and a signal from the sensor And a solid oxide fuel cell system.   The air header has two supply ports, a supply port for supplying high-temperature gas for activation and a supply port for supplying gas for power generation, and separates the gas supply line for activation and the gas supply line for power generation. The solid oxide fuel cell system according to claim 4, wherein the solid oxide fuel cell system is used.   A module composed of a plurality of solid oxide fuel cells, an air header arranged on the upper part of the module, a preheater for preheating power generation air supplied to the air header, and power generation air supplied to the air header Means for supplying combustion gas to the air header, a starting fuel line and a starting air line connected to the air header and the starting burner, and a solid oxide fuel cell of the module A sensor for detecting a fuel cell temperature and a fuel cell current or voltage; and based on a signal from the sensor, it is determined that the fuel cell temperature and the fuel cell current or voltage have reached or exceeded a predetermined threshold. A system control device that transmits a stop signal to the start burner; a first control device that controls the start burner based on a control signal of the system control device; Solid oxide fuel cell system characterized by comprising a second control device for controlling the preheater in accordance with a control signal of the system controller.   A module composed of a plurality of solid oxide fuel cells, an air header arranged on the upper part of the module, a preheater for preheating power generation air supplied to the air header, and power generation air supplied to the air header Means for supplying combustion gas to the air header, a starting fuel line and a starting air line connected to the air header and the starting burner, and a solid oxide fuel cell of the module A sensor for detecting temperature, current, and voltage; and a system control device for transmitting a stop signal to the start burner based on a signal from the sensor; after igniting the start burner, module temperature Tc, module When the temperature increase rate ΔTh satisfies the condition I of Tc> Tmin and ΔTh1 <ΔTh <ΔThmax, the air supplied to the air header and Step I of increasing the amount of anode gas supplied to the joule to start power generation and adjusting the combustion amount of the start burner when the above condition I is not satisfied (where Tmin is the module temperature necessary for power generation, ΔTh1 includes the minimum value of the module temperature increase rate to be controlled, and ΔThmax indicates the module temperature increase rate threshold for preventing damage of the fuel cell). After the start of power generation, when the condition II of Ta>Tc> Tmin, ΔTh1 <ΔTh <ΔThmax, Vc> V ₀ is satisfied, the amount of anode gas supplied to the module and the amount of cathode air supplied to the air header are increased. Step II to increase the generated current, decrease the combustion amount of the start burner, and maintain the generated current at a predetermined value when the condition II is not satisfied (where Ta is a module capable of stopping the start burner) The solid oxide fuel cell system according to claim 7, further comprising: a temperature threshold value, V ₀ , which is a module voltage required for power generation. When the condition II is satisfied, when the amount of generated current is increased and the combustion amount of the starting burner is decreased, the condition III of Tmax>Tc> Ta, Vc> V ₀ , I> Ia is satisfied , Stop the start burner, shift to rated power generation, and when the condition III is not satisfied, increase the anode gas amount for the module and increase the cathode air amount for the air header (where Tmax is the module) 9. The solid oxide fuel cell system according to claim 8, including a maximum allowable temperature of I, a generated current, and Ia a module current threshold at which the start burner can be stopped.   10. The solid oxide fuel cell system according to claim 9, wherein after the start burner is stopped in the step III, the anode gas flow rate and the cathode gas flow rate are increased to shift to rated power generation.   10. The solid oxide fuel cell system according to claim 9, wherein from the start to the rated power generation is executed in the order of the step II and the step III following the step I. 11.

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