KR20090112822A - Fuel cell system and control method thereof - Google Patents

Abstract

PURPOSE: A fuel cell system and a control method thereof are provided to rapidly increase the temperature of a stack by supplying warm water generated during initial driving to a stack. CONSTITUTION: A fuel cell system includes a reformer(20) and a stack(30). The reformer generates reformate gas. The stack generates energy by supplying reformate gas generated in a reformer. A control method of a fuel system comprises the steps of: driving a reformer and heating heat media by heat energy generated by the driving of a reformer; heating a stack to the normal operating temperature by using heated heat media; and supplying the reformate gas to the stack after the stack reaches the normal operating temperature.

Description

FUEL CELL SYSTEM AND CONTROL METHOD THEREOF}

The present invention relates to a fuel cell system and a control method thereof, and more particularly, a method of heating a stack of a fuel cell system by circulating a heating medium heated by heat generated from a reformer and heating the stack of the fuel cell system is performed. The present invention relates to a fuel cell system and a control method thereof capable of raising the temperature economically and quickly to a state in which operation is possible.

In general, a fuel cell system is a device that can obtain electrical and thermal energy through electrochemical reactions of oxidation and reduction. Fossil energy, such as petroleum and coal, has a limited amount of reserves, resulting in energy depletion gradually becoming a reality, and environmental pollution due to various pollutants emitted in the process of using it.

Fuel cell systems are being spotlighted as alternative energy sources that can solve energy depletion and environmental pollution problems because electric energy and heat energy are generated through highly efficient electrochemical reactions.

The fuel cell system includes a fuel supply unit, a reformer, a stack, a coolant supply unit, and the like, as disclosed in Korean Patent Application No. 1998-0016383 and Korean Patent Application No. 2003-0047158.

Hereinafter, an operation of a fuel cell system according to an exemplary embodiment will be described in detail with reference to FIG. 1.

The fuel cell system 110 according to an exemplary embodiment supplies a hydrocarbon-based (CH-based) fuel such as LNG, LPG, kerosene, etc. to the reformer 120 from the fuel supply unit 150.

The reformer 120 is subjected to desulfurization so that the supplied fuel undergoes reforming and carbon monoxide removal. The fuel, which has undergone a series of processes, has a low carbon monoxide content and hydrogen as a main component, is mixed with the external inlet air supplied from the external inlet air supply unit 170, and is supplied as a reforming gas to the stack 130. .

The stack 130 is provided by stacking a plurality of single cells in which an electrochemical reaction occurs. The single cell is a membrane-electrode assembly (MEA) in which a fuel electrode and an air electrode are disposed around an electrolyte membrane. In the anode, the hydrogen is separated into hydrogen ions and electrons by a catalyst to generate electricity. In the cathode, the hydrogen ions and electrons combine with oxygen to generate water.

The coolant supply unit circulates the coolant with a cooling plate inserted between several single cells to discharge heat generated in the electrochemical reaction process to the outside of the stack 130.

On the other hand, since the chemical reaction does not take place in earnest for a predetermined time from the initial start-up of the fuel cell system 110, the state in which the temperature of each component of the fuel cell 110 does not reach a temperature for normal operation continues. Since the minimum temperature required for the normal operation of the fuel cell system 110 varies depending on each component, even if a portion requiring a low temperature condition is operating normally, a portion requiring a high temperature condition does not operate normally. Is generated.

For example, a reformer (not shown) included in the reformer 120 reaches an operational temperature to produce gas, while a shift reactor (not shown) included in the reformer 120 is still capable of functioning normally. Situations may occur in which carbon monoxide cannot be effectively removed because the temperature is not reached.

In this case, the gas passed through the shift reactor (not shown) contains about 75% hydrogen and about 5% carbon monoxide. Damage to the stack 130 may occur when a gas containing about 5% of carbon monoxide is supplied to the stack 130, and thus, even though about 75% of useful hydrogen is included, it may be used as a reforming gas for generating electricity. none. Therefore, until the reformed gas containing carbon monoxide in a predetermined range is produced at a constant temperature, the produced gas is exhausted by the combustion burner 160 or the fuel supply unit 150 for combustion.

However, the conventional fuel cell system takes a considerable time from the initial start-up to the temperature at which the fuel cell system can operate normally.

In order to solve this problem, a method of heating the fuel cell system with an electric heater and raising it to a normal operating temperature has been proposed. However, since the heat is required to be applied to the fuel cell system for a considerable time, the electrical energy consumption is uneconomical. .

The present invention is to solve such a problem, an object of the present invention is to operate the stack of the fuel cell system by applying a method of heating the stack of the fuel cell system is circulated heating the heating medium by the heat generated in the reformer This is to raise the temperature economically and quickly until possible.

A fuel cell system and a method for controlling a fuel cell system according to the present invention for achieving the above object include a reformer for generating reformed gas, and a stack for generating energy by receiving the reformed gas generated in the reformer. In the control method of the fuel cell system, after the operation of the reformer, heating the heat medium by the heat energy generated by the operation of the reformer, using the heated heat medium to raise the stack to the normal operating temperature And a normal start for supplying the reformed gas to the stack after the stack reaches a normal operating temperature.

The initial startup is performed by circulating the fruit medium supplied to the stack through a first startup for supplying the heated fruit object to the stack, and a circulating heating circuit provided between the reformer and the stack. It is preferred to include a second start for heating the stack.

In the first startup, the heated heating medium can be directly supplied to the cold plate of the stack.

In the first operation, the heated heating medium may be supplied to a cooling liquid reservoir provided in the stack and then supplied to a cooling plate of the stack.

In the first operation, the heated heating medium can be simultaneously supplied to the cooling plate of the stack and the cooling liquid reservoir provided in the stack.

In the first operation, after the temperature of the reformer provided in the reformer reaches the reformer operation start temperature, the first fruit is preferably heated through a heat exchanger of the reformer and supplied to the stack.

The first start can be performed after discharging the fruit object stored in the stack to the outside.

In the first operation, when the supply amount of the heated fruit object reaches the upper limit of the amount of fruit object in the stack, it is preferable to stop the supply of the heat object to the stack.

In the first operation, when the supply amount of the heated fruit object reaches the upper limit of the amount of fruit object of the stack, the part of the fruit object accommodated in the stack is discharged, and the corresponding fruit object is discharged. It is possible to receive a positive amount of said fruit entity.

The first starting is preferably performed after discharging the fruit object stored in the stack to the outside.

In the first operation, it is possible to stop the supply of the thermal object to the stack when the supply amount of the heated fruit object reaches the upper limit of the amount of fruit object in the stack.

In the first operation, when the supply amount of the heated fruit object reaches the upper limit of the amount of fruit object of the stack, the part of the fruit object accommodated in the stack is discharged, and the amount corresponding to the fruit object discharged. It is preferable to be supplied with the fruit entity of.

It is determined whether the temperature of the shift reactor provided in the reformer has reached the shift reactor set temperature, and if the temperature of the shift reactor reaches the shift reactor set temperature, stopping the first start and switching to the second start. It is possible.

Preferably, the shift reactor set temperature is 100 degrees Celsius.

In the second startup, it is possible that the fruit is forced circulation through the circulation heating circuit.

In the second operation, it is possible to totally circulate the heating circuit so that the fruit entity is naturally circulated by the heat siphon phenomenon.

Start supply of fuel to the reformer,

It is preferable to supply the reformed gas generated by the operation of the reformer to the heating burner of the reformer.

In the second startup, it is determined whether the temperature of the stack has reached the stack operating temperature, and if the stack temperature is equal to or higher than the stack operating temperature, the stack gas is heated and the reformed gas is circulated through the fruit medium. It is possible to stop the supply to the heating burner and supply the reformed gas to the stack.

The reformer is provided with a reformer, and in the initial start-up, it is determined whether the temperature of the reformer has reached the upper limit of the reformer operation temperature, and when the temperature of the reformer is higher than the upper limit of the reformer operation temperature, the reformer is not heated. It is preferable to control the temperature of the reformer by supplying the fruit individual.

The reformer is provided with a reformer, and in the normal startup, it is determined whether the temperature of the reformer has reached the upper limit of the reformer operation temperature, and the temperature of the reformer is higher than the upper limit of the reformer operation temperature. It is possible to control the temperature of the reformer by supplying the heated fruit medium passing through a heat exchanger.

The fruit entity is preferably water (Water).

In addition, the fuel cell system and the fuel cell system control method according to the present invention includes a reformer for emitting reformed gas; A stack for generating energy by receiving the reformed gas generated by the reformer; And a circulating heating circuit provided between the reformer and the stack to increase the temperature of the stack by using heat generated in the reformer during initial startup, wherein the circulating heating circuit is a fruit medium from the reformer to the stack. It can also be achieved by a fuel cell system including a cooling plate flow path for supplying a circulating flow path for returning the fruit medium from the stack to the reformer.

The cooling plate flow path may be provided between a heat exchanger provided in the reformer and a cooling plate provided in the stack.

The cooling plate flow path may be provided between a heat exchanger provided in the reformer and a cooling liquid reservoir provided in the stack.

The cooling plate flow path may be provided between the heat exchanger provided in the reformer and the cooling plate of the stack and between the heat exchanger and the cooling liquid reservoir provided in the stack.

The cooling plate flow passage is provided with a valve for controlling the supply of the fruit medium, the circulation passage is preferably provided with a valve for controlling the circulation of the fruit medium.

The cooling plate provided in the stack may be provided with a drain pipe extending outward to induce drainage of the fruit object stored in the cooling plate, and the drain pipe may be provided with a valve for controlling the drainage of the fruit object.

The reformer is provided with a reformer, and the reformer is provided with a flow path for supplying the fruit medium at room temperature to the reformer and a flow path for supplying the fruit medium branched and heated in the cooling plate flow path to the reformer. It is preferable.

The fuel cell system and its control method according to the present invention are economical to the state that the stack of the fuel cell system can be operated normally by applying a method of heating the stack of the fuel cell system by circulating the heat heated by the heat generated from the reformer. The temperature can be raised quickly and quickly.

In addition, the fuel cell system and the control method according to the present invention can quickly increase the temperature of the stack by supplying the hot water generated during the initial startup to the stack.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a view showing the operation of the fuel cell system according to the first embodiment of the present invention.

As shown in the drawing, the fuel cell system 10 according to the first embodiment of the present invention includes a reformer 20 in which a reforming reaction proceeds, a stack 30 for generating electricity, and a coolant. Cooling water reservoir 40 for fresh water, circulating heating circuit 71 provided between the heat exchanger 24 of the reformer 20 and the cooling plate 36 of the stack 30, and the hot water heated by the heat exchanger 24. It includes a cooling plate flow path 72 for supplying the cooling plate (36).

The reformer 20 converts the hydrocarbon-based fuel 50 into a reformed gas mainly composed of hydrogen through a reforming reaction. The reformer 20 includes a heating burner 22, a reformer 23, a shift reactor 26, a mixer 27, and a carbon monoxide remover 29.

The heating burner 22 generates heat by burning hydrocarbon-based fuel 50 such as LNG, LPG, kerosene, and the like. The heat generated from the heating burner 22 is supplied to the reformer 23 to promote the reforming reaction by the heat.

The reformer 23 is heated by the heating burner 22 and is a portion where the reforming reaction proceeds substantially. When the fuel cell system 10 is operated for the first time, air and fuel 50 are supplied to the heating burner 22 to be ignited, and the operation of the heating burner 22 is started. The ignited heating burner 22 heats the reformer 23 so that the temperature of the reformer 23 reaches 300 degrees Celsius, which is a reformer operation start temperature. In this case, all the valves inside the fuel cell system 10 are closed except for an essential part of the operation of the heating burner 22 for heating the reformer 23. Therefore, the heat generated by the heating burner 22 is used to heat the reformer 23 completely. When the first operation (dotted line), which is the first stage of the initial startup divided into two stages, is reached when the reformer operation start temperature is reached, the first valve 91 is opened so that water 64, which is pure water (DI water, deionized water), Pass through heat exchanger (24). The water 64 heated through the heat exchanger 24 is supplied to the cold plate 36 of the stack 30 along the cold plate channel 72 and heats the stack 30. At the same time, the heating burner 22 continuously heats the reformer 23 so that the temperature of the reformer 23 reaches 500 degrees Celsius which is the upper limit of the reformer operation. The reformer 23 exhibits optimum performance by setting the upper limit temperature and the lower limit temperature of the reformer operation at the upper limit of the operation time. In order to keep the temperature of the reformer 23 within the optimum range, when the temperature of the reformer 23 exceeds the upper limit of the reformer operation temperature, the fourth valve 94 provided on the flow path for supplying water 64 to the reformer 23 is provided. Open). When the fourth valve 94 is opened, the room temperature water 64 is supplied to the reformer 23, so that the rise of the reformer 23 temperature is limited. The water supplied to the reformer 23 through the fourth valve 94 takes heat from the reformer 23 and is converted into high temperature steam. The hot steam is supplied to the shift reactor 26 to raise the temperature of the shift reactor 26 and then discharged to the outside. The fourth valve 94 is frequently opened and closed during the initial startup of the fuel cell system 10 by a control signal of a controller (not shown), so that the temperature of the reformer 23 is maintained within a predetermined range.

The shift reactor 26 receives a gas in which hydrogen is a major component and reduces the component ratio of carbon monoxide contained therein. The gas supplied from the reformer 23 contains about 75% of hydrogen, about 15% of carbon dioxide, and about 5% of carbon monoxide. In the shift reactor 26, the following reaction takes place.

CO + H ₂ 0 ↔ CO ₂ + H ₂

When the temperature and the like of the shift reactor 26 are within the normal operating range, the forward reaction of the above-described reaction formula is activated to reduce the carbon monoxide content by about 0.5%. For the normal operation, the shift reactor 26 should be heated to a temperature of 100 degrees Celsius or more, which is a shift reactor set temperature by receiving heat from thermal by-products including water vapor due to the heating of the reformer 23. When the shift reactor 26 is higher than the shift reactor set temperature, the fuel 50 passed through the water 64 and the desulfurizer 62 is supplied to the reformer 23 so that the reforming reaction proceeds in the reformer 23. . The reforming reaction proceeds and the gas generated in the reformer 23 is supplied to the shift reactor 26. On the other hand, when the reforming reaction proceeds in the reformer 23 and gas is generated, the temperature of the stack 30 does not reach the stack operating temperature, the sixth valve 96 is opened to open the shift reactor 26. The second start (single-dashed line) which supplies the gas which passed through to the heating burner 22 advances. Since the gas generated in the second start (single-dashed line) state in which the shift reactor 26 is higher than the shift reactor set temperature contains sufficient hydrogen, a combustion reaction for supplying the heating burner 22 to heat the reformer 23. You can proceed. Therefore, when the second start (dashed dashed line) is started and gas is supplied from the shift reactor 26 to the heating burner 22, the fuel 50 supplied to the heating burner 22 is reduced or stopped. ) Can be saved. On the other hand, if the shift reactor 26 is higher than the shift reactor set temperature and the temperature of the stack 30 is also higher than the stack operating proper temperature, the sixth valve 96 is shut off and the normal operation (solid line) is performed, so that the gas is mixed (27). Is supplied.

The mixer 27 is supplied with the gas generated in the shift reactor 26 when the normal starting (solid line) proceeds. The mixer 27 mixes the gas supplied from the shift reactor 26 and the external inlet air 66 according to a control signal of a controller (not shown). The mixed gas mixed in the mixer 27 is supplied to the carbon monoxide remover 29 when the stack 30 is a low temperature type.

The carbon monoxide remover 29 reduces the amount of carbon monoxide within an allowable range through a selective oxidation (PROX, PReferential Oxidation) reaction. In the carbon monoxide remover 29, a series of reactions are performed as follows.

CO + 0.5O ₂ ↔ CO ₂

When the reaction proceeds in the carbon monoxide remover 29 in the forward direction, it means that the carbon monoxide is converted to carbon dioxide to reduce the content of carbon monoxide. The carbon monoxide passes through there 29 and the content of carbon monoxide is reduced to less than 10 parts per million (ppm). The carbon monoxide remover 29 is not necessary in the case of the high temperature stack 30 which is resistant to carbon monoxide, but is required in the case of the low temperature stack 30. The reformed gas discharged from the carbon monoxide remover 29 is supplied to the stack 30.

The stack 30 generates electrochemical and thermal energy by causing an electrochemical reaction on the supplied reformed gas. The stack 30 is provided by stacking a plurality of single cells (not shown) in which oxidation and reduction are performed and electricity is generated. In FIG. 2 of the present invention, for convenience of description, the shapes of the fuel electrode 32, the air electrode 34, and the cooling plate 36 are conceptually expressed, but a single cell (not shown) is mainly formed around an electrolyte membrane (not shown). The fuel electrode 32 and the air electrode 34 are arranged, and a plurality of single cells (not shown) are stacked, and then the cooling plate 36 is inserted. End plates 38 are provided on left and right sides of the stack 30.

In the fuel electrode 32 and the air electrode 34, electricity is generated by oxidation and reduction reaction of hydrogen. That is, in the anode 32, hydrogen is separated into hydrogen ions and electrons by a catalyst, and electricity is generated. In the cathode 34, hydrogen ions and electrons generated in the anode 32 combine with oxygen to generate water.

The cooling plate 36 is provided between the plurality of fuel electrodes 32 and the air electrodes 34 laminated to appropriately adjust the temperature of the stack 30. That is, in the process of the first and second startups (dotted line and one-dot chain line), which are the initial startups, heat is transferred from the heat medium in the circulating heating circuit 71 and the cooling plate flow path 72 to the cooling plate 36, whereby the stack ( In the process of increasing the temperature of 30) and normal starting (solid line), the ninth and tenth valves 99 and 100 provided in the cooling liquid flow path 73 are frequently opened and closed by a control signal of a controller (not shown). The temperature of 30 is kept constant.

The end plate 38 is provided on the left and right outermost sides of the stack 30. The end plate 38 is provided with a through hole (not shown) for the inflow and outflow of the reformed gas introduced into the stack 30. In addition, various fixing screws (not shown) are coupled to the end plate 38 to couple the unit cells (not shown). The end plate 38 is made of a rigid metal such as duralumin because it supports the overall weight of the stack 30 and maintains its shape.

The circulation heating circuit 71 is a circulation system provided between the heat exchanger 24 of the reformer 20 and the cooling plate 36 of the stack 30. The circulation heating circuit 71 heats the cooling plate 36 economically and rapidly as water naturally circulates due to a thermal siphon phenomenon at the initial startup of the fuel cell system 10. Since water is naturally circulated by the heat siphon phenomenon, it is not necessary to add a separate forced circulation device such as a pump, so that there is no additional energy consumption and an increase in the cost of adding the device. The thermosiphon phenomenon means two phase flow where gravity acts. Specifically, the circulation heating circuit 71 is filled with water, which is a fruit entity, and liquid water is supplied from the heating burner 22 and the reformer 23 in the heat exchanger 24 serving as a heating unit. It absorbs the transferred heat and phase changes into hot gaseous water vapor. Vaporized, vaporized and expanded at the same time as the volume is reduced, moves along the circulation heating circuit 71 to the cold plate 36 located at the top relative to the heat exchanger 24. The cooling plate 36 serves as a condenser. The high temperature water vapor loses heat to the stack 30 in the course of passing through the cooling plate 36 to become liquid water, and undergoes a phase change in which the volume decreases and the density increases. Liquid water of increased density moves to the heat exchanger 24 located at the lower end by gravity. By repeated heating and cooling, the water undergoes a phase change between the liquid and the gas, and naturally circulates inside the circulating heating circuit 71 without a separate forced circulation device to heat the stack 30. The circulation heating circuit 71 is provided with a fifth valve 95. The fifth valve 95 is opened during the second start (dotted and dashed line) operation of the fuel cell system 10. Circulation due to the heat siphon phenomenon occurs in earnest during the second startup (one dashed line) in which the heat exchanger 24 is sufficiently heated. The fifth valve 95 is shut off when the temperature of the stack 30 is higher than the stack operating temperature, and at the same time, the circulation through the circulation heating circuit 71 is also stopped.

The cooling plate flow path 72 is a flow path for supplying hot water heated by the heat exchanger 24 to the cooling plate 36. When the first start (dotted line) is started, the first valve 91 and the second valve 92 provided on the cooling plate flow passage 72 are opened. The water 64 at room temperature passes through the first valve 91 and is supplied to the heat exchanger 24. The heat 64, which absorbs the heat of the heating burner 22 and the reformer 23 in the heat exchanger 24 and rises in temperature, is supplied to the cooling plate 36 through the second valve 92, and the cooling plate 36 Heat is transferred to stack 30 at 36 to raise the temperature of stack 30. On the other hand, the water stored in the cooling plate 36 of the stack 30 before the water 64, the temperature of which has risen in the heat exchanger 24, is supplied to the cooling plate 36. Can be discharged in advance. By discharging the water stored in the cooling plate 36 in advance, the heat capacity of the entire stack 30 is reduced so that the thermal energy retained by the supplied hot water contributes to the temperature rise of the stack 30. It is possible to induce a rapid temperature rise of (30), even if the ion conductivity of the water existing in the cooling plate 36 is higher than the reference value can be discharged the water stored in the cooling plate 36. Furthermore, in order to continuously increase the temperature of the stack 30 even after the water level inside the cooling plate 36 reaches the target upper limit amount, the first, second, and third valves 91, 92, and 93 are controlled to open and close the cooling. It is possible to discharge the hot water stored in the plate 36 and receive fresh water at the same time.

Hereinafter, a control method of the fuel cell system shown in FIG. 2 according to the first embodiment of the present invention will be described with reference to FIGS. 3A and 3B.

When the fuel cell system 10 is operated for the first time, each component of the fuel cell system 10 is not in a normal temperature range in which the electrochemical reaction proceeds to produce electric energy, thereby blocking various valves provided therein. The fuel cell system 10 is initialized (S10) and the heating burner 22 is operated to heat the reformer 23 (S20).

It is determined whether or not the temperature of the reformer 23 reaches 300 degrees Celsius which is a reformer operation start temperature (S30).

When the temperature of the reformer 23 exceeds the reformer operation start temperature, the first and second valves 91 and 92 provided in the cooling plate flow path 72 are opened to supply the heat medium to the cooling plate 36 ( S40). At this time, the third valve 93 is opened first to discharge the water stored in the cooling plate 36, and then the third valve 93 is shut off and the first and second valves 91 and 92 are opened to provide hot water. It is possible to feed it. In addition, the supplied hot water is discharged to the outside via the cooling plate 36 and new hot water can be continuously supplied. That is, in order to continuously increase the temperature of the stack 30 even after the water level inside the cooling plate 36 reaches the target upper limit amount, the opening and closing of the first, second, and third valves 91, 92, and 93 are controlled to cool. It is possible to discharge the hot water stored in the plate 36 and receive fresh water at the same time. When hot water is supplied through the cooling plate flow path 72, the temperature of the cooling plate 36 is increased, and eventually the temperature of the entire stack 30 is increased.

Since the heating burner 22 continues to heat the reformer 23, it is determined whether or not the temperature of the reformer 23 reaches 500 degrees Celsius which is the upper limit of the reformer operation temperature (S50).

When the temperature of the reformer 23 exceeds the upper limit of the reformer operation temperature, the temperature of the reformer 23 is controlled by controlling the opening and closing of the fourth valve 94 provided on the flow path for supplying water 64 to the reformer 23. Control (S60). When water 64 at room temperature is supplied to the reformer 23, the temperature of the reformer 23 is decreased. When the supply of water 64 is stopped, the temperature of the reformer 23 is increased by the heat generated by the heating burner 22. do.

The amount of water accommodated in the cooling plate 36 is compared with the upper limit of storage (S70).

When the amount of water contained in the cooling plate 36 is greater than or equal to a predetermined storage upper limit by comparing the amount of water contained in the cooling plate 36 with the upper limit of water, the first valve 91 is blocked to determine the amount of water contained in the cooling plate 36. The amount is kept constant (S80). In this case, in order to continuously raise the temperature of the stack 30 even after the water level inside the cooling plate 36 reaches the target upper limit amount, the opening and closing of the first, second and third valves 91, 92 and 93 are controlled. As described above, it is possible to discharge hot water stored in the cooling plate 36 and to receive new water at the same time.

It is determined whether the temperature of the shift reactor 26 is higher than the shift reactor set temperature (S90). The reformer 23 is directly heated by the heating burner 22, so that the temperature rises relatively quickly, whereas the shift reactor 26 is heated by the steam generated by the reformer 23 or by the heat generated by the reformer 23. Heated indirectly. Therefore, the temperature of the shift reactor 26 is lower than the temperature of the reformer 23, and the temperature rises slower than the reformer 23. Since the temperature of the shift reactor 26 is higher than that of the reformer 23, the temperature of the shift reactor 26 is relatively low even though the temperature of the reformer 23 reaches a relatively high temperature of 500 degrees Celsius. The shift reactor set temperature of 100 degrees Celsius may not be reached.

If the temperature of the shift reactor 26 is higher than the shift reactor set temperature, the second reactor (single dashed line) is entered during the initial startup of the fuel cell system 10. That is, it is determined whether the temperature of the stack 30 reaches a stack operating temperature at which the stack 30 can operate normally (S100). The stack operating temperature is set differently depending on whether the stack 30 is cold or hot.

If the temperature of the stack 30 is lower than the stack operating temperature, the first valve 91 is blocked and the fifth valve 95 is opened (S110). As described above, the fifth valve 95 is an opening and closing device provided on the circulation heating circuit 71. Although the fifth valve 95 may be opened during the first startup (dotted line), the temperature inside the circulation heating circuit 71 may not be high enough to cause a heat siphon phenomenon in earnest during the first startup (dotted line). However, when the temperature of the shift reactor 26 also enters the second start (single-dashed line) beyond the shift reactor set temperature, the inside of the circulation heating circuit 71 has a temperature above the boiling point of water where a heat siphon phenomenon may occur. Leads to Therefore, when the temperature of the stack 30 is lower than the stack operating temperature, the stack 30 is heated by opening the fifth valve 95 so that a heat siphon phenomenon occurs in earnest. The heat siphon phenomenon does not require a separate pressurization means such as a pump, is naturally convection due to the temperature difference, and heat is transferred to the stack 30, and thus it is an economical method of rapidly raising the temperature of the stack 30. On the other hand, a forced circulation device may be added to make natural convection more smooth. In this case, the size and energy consumption of the forced circulation device are reduced compared to the case of not using the heat siphon phenomenon. to be.

While opening the fifth valve 95, the fuel 50 is supplied to the reformer 23, the fourth valve 94 is controlled, and the temperature of the reformer 23 is adjusted (S120). The fuel 50 is desulfurized through the desulfurizer 62 and supplied to the reformer 23, and water 64 is supplied to the reformer 23 through the fourth valve 94. When water 64 and the desulfurized fuel 50 are supplied to the reformer 23, reforming reaction is performed in the reformer 23 and gas is generated. Gas by the reforming reaction of the reformer 23 passes through the heat exchanger 23 and is supplied to the shift reactor 26. Since the shift reactor 26 is above a shift reactor set temperature capable of effectively removing carbon monoxide, when the shift reactor 26 passes, gas containing less than an appropriate amount of carbon monoxide is generated.

The gas is generated in the shift reactor 26 and the sixth valve 96 is opened to supply the generated gas to the heating burner 22 (S130). Since the temperature of the stack 30 is lower than the stack operating temperature, the stack 30 is not yet operating properly. Therefore, the gas generated in the shift reactor 26 is supplied to the heating burner 22 without being supplied to the stack 30. Since the gas generated in the shift reactor 26 is supplied to the heating burner 22, the supply of the fuel 50 can be reduced or completely stopped, so that the operation of the fuel cell system 10 becomes economical.

When the temperature of the stack 30 is equal to or higher than the stack operating temperature, the fuel cell system 10 enters the normal startup (solid line).

Normal start (solid line) of the fuel cell system 10 is initiated by blocking the fourth, fifth and sixth valves 94, 95 and 96 (S140). When the fifth valve 95 is blocked, the flow of the fluid on the circulation heating circuit 71 is stopped and the progress of the heat siphon phenomenon is stopped. Therefore, heat transfer to the stack 30 through the circulation heating circuit 71 is stopped. When the fourth valve 94 is shut off, the supply of water 64 directly to the reformer 23 is stopped. The fourth valve 94 which directly supplies the room temperature water 64 to the reformer 23 is shut off, so that the temperature of the reformer 23 is due to a temperature difference between the water 64 at room temperature and the high temperature reformer 23. The possibility of a significant change is eliminated. When the sixth valve 96 is shut off, gas generated in the shift reactor 26 is not supplied to the heating burner 22.

While blocking the fourth, fifth, and sixth valves 94, 95, and 96, the second valve 92 is blocked, and the first, seventh, and eighth valves 91, 97, and 98 are opened (S150). When the first valve 91 is opened, the temperature is raised while water 64 at room temperature passes through the heat exchanger 24. The seventh valve 97 passes through the heat exchanger 24 and is provided on a flow path through which water 64 having a raised temperature is supplied to the reformer 23. By closing the second and fourth valves 92 and 94 and opening the first and seventh valves 91 and 97, the reformer 23 is supplied with the heated water 64 instead of the water 64 at room temperature. There is less room for the temperature of (23) to change drastically. When the eighth valve 98 is opened, the reformed gas passing through the carbon monoxide remover 29 is supplied to the stack 30. The gas generated in the shift reactor 26 is mixed with the external inlet air 66 and supplied to the carbon monoxide remover 29. The carbon monoxide remover 29 is required when the stack 30 is of a low temperature type.

When the eighth valve 98 is opened to supply the reformed gas, the stack 30 is operated in earnest (S160).

When the stack 30 is operated, the ninth and tenth valves 99 and 100 are opened and closed by a control signal, and the temperature of the stack 30 is maintained within an appropriate range (S190). The ninth and tenth valves 99 and 100 are provided on the cooling liquid flow path 73. When the stack 30 is operated in earnest, a large amount of heat is generated at the same time as the electrical energy is generated in the stack 30. If the generated heat is not discharged, the stack 30 may not operate normally. Therefore, the cooling liquid is supplied to the cooling plate 36 through the cooling liquid flow path 73 communicated with the cooling liquid reservoir 40 to adjust the temperature of the stack 30. The ninth and tenth valves 99 and 100 are provided on the coolant flow path 73 to adjust the amount of the coolant so that the stack 30 can operate in an appropriate temperature range.

4 is a view showing the operation of the fuel cell system according to the second embodiment of the present invention, and will be described only parts different from the first embodiment of the present invention, the same parts as the first embodiment if necessary for explanation The same reference numerals are used to refer to the reference numerals, and the changed parts are referred to by the reference numerals added with 'a'.

In the fuel cell system 10a according to the second embodiment of the present invention, the cooling plate flow path 72a is directly connected to the cooling liquid reservoir 40.

Since the cooling plate flow passage 72a is directly connected to the cooling liquid reservoir 40, the ninth valve 99 is opened at the same time as the first start (dotted line) is started, and the hot water supplied to the cooling liquid reservoir 40 is cooled to the cooling liquid passage ( It is supplied to the cooling plate 46 through 73a). According to the second embodiment, like the first embodiment, the coolant can be discharged or exchanged at the time of initial startup through a valve (not shown) provided separately on the third valve 93 or the coolant flow path 73.

FIG. 5 is a view illustrating the operation of a fuel cell system according to a third embodiment of the present invention. FIG. 5 is only a part different from the first embodiment of the present invention. The same reference numerals are used to refer to the reference numerals, and for the changed parts, reference numerals with the addition of 'b' will be cited.

In the fuel cell system 10b according to the third embodiment of the present invention, the cooling plate flow path 72b is branched from the separator 78b to the first cooling plate flow path 74b and the second cooling plate flow path 76b.

The first cooling plate flow path 74b is directly supplied to the cooling plate 36 to contribute to the temperature increase of the stack 30, and the second cooling plate flow path 76b is supplied to the cooling liquid reservoir 40 and then the cooling liquid flow path ( 73b) is supplied to the cooling plate 36 to raise the temperature of the stack 30.

In the above-described embodiments, a case where a carbon monoxide remover is provided is mainly described assuming a low temperature stack, but whether the carbon monoxide remover is included or not depends on the characteristics of each component of the fuel cell system including the stack.

As described above, the present invention is not limited to the described embodiments, and various modifications and changes can be made without departing from the spirit and scope of the present invention, which will be apparent to those skilled in the art. Therefore, such modifications or variations will have to be belong to the claims of the present invention.

1 is a view showing the operation of a fuel cell system according to a conventional embodiment.

2 is a view showing the operation of the fuel cell system according to the first embodiment of the present invention.

3A and 3B are flowcharts illustrating a control method of the fuel cell system of FIG. 2.

4 is a view showing the operation of a fuel cell system according to a second embodiment of the present invention.

5 is a diagram illustrating the operation of a fuel cell system according to a third embodiment of the present invention.

* Description of symbols on the main parts of the drawings *

10 fuel cell 20 reformer

22: heating burner 23: reformer

26: shift reactor 29: carbon monoxide remover

30 stack 36 cold plate

40: coolant reservoir 71: circulation heating circuit

72: cooling plate flow path 73: cooling liquid flow path

Claims (25)

In the control method of a fuel cell system including a reformer for generating a reformed gas, and a stack for generating energy by receiving the reformed gas generated from the reformer, After starting the reformer, the initial heating to heat the fruit medium by the heat energy generated by the operation of the reformer, and to raise the stack to the normal operating temperature using the heated fruit medium, And a normal operation of supplying the reformed gas to the stack after the stack reaches a normal operating temperature. The method of claim 1, The initial startup, A first start for supplying the heated fruit entity to the stack; And a second operation for heating the stack by circulating the fruit material supplied to the stack through a circulating heating circuit provided between the reformer and the stack. The method of claim 2, In the first start, The heated heating medium is directly supplied to the cooling plate of the stack control method of a fuel cell system. The method of claim 2, In the first start, The heated heating medium is supplied to the cooling liquid reservoir provided in the stack, and then supplied to the cooling plate of the stack. The method of claim 2, In the first start, The heated heating medium is supplied to the cooling plate of the stack and the cooling liquid reservoir provided in the stack at the same time control method of the fuel cell system. The method of claim 2, The first start is, And after the temperature of the reformer provided in the reformer reaches a reformer operation start temperature, the fruit medium is heated by passing through a heat exchanger of the reformer and supplied to the stack. The method of claim 2, The first start is, A control method of a fuel cell system formed after discharging the fruit material stored in the stack to the outside. The method of claim 2, In the first start, And supplying the thermal object to the stack when the supply amount of the heated fruit object reaches the upper limit of the fruit object capacity of the stack. The method of claim 2, In the first start, When the supply amount of the heated fruit object reaches the upper limit of the amount of fruit object in the stack, a part of the fruit object contained in the stack is discharged, and the fruit object in an amount corresponding to the discharged fruit object is supplied. Control method of receiving fuel cell system. The method of claim 2, It is determined whether the temperature of the shift reactor provided in the reformer has reached the shift reactor set temperature, And stopping the first start and switching to the second start when the temperature of the shift reactor reaches the set temperature of the shift reactor. The method of claim 10, And the shift reactor set temperature is 100 degrees Celsius. The method of claim 2, In the second start, The control method of the fuel cell system in which the fruit is forced circulation through the circulation heating circuit. The method of claim 2, In the second start, And total heat circulation of the circulating heating circuit so that the fruit is naturally circulated by a heat siphon phenomenon. The method of claim 2, Start supply of fuel to the reformer, A control method of a fuel cell system for supplying a reforming gas generated by the operation of the reformer to the heating burner of the reformer. The method of claim 14, In the second start, It is determined whether the temperature of the stack has reached the stack operating temperature, and if the temperature of the stack is greater than the stack operating temperature, And controlling the heating of the stack through the circulation of the fruit medium and supplying the reformed gas to the heating burner, and supplying the reformed gas to the stack. The method of claim 1, The reformer is provided with a reformer, At the initial startup, It is determined whether the temperature of the reformer has reached the upper limit of the reformer operating temperature, and when the temperature of the reformer is higher than the upper limit of the reformer operating temperature, And controlling the temperature of the reformer by supplying the heat medium not heated to the reformer. The method of claim 1, The reformer is provided with a reformer, In the normal operation, It is determined whether the temperature of the reformer has reached the upper limit of the operating temperature of the reformer, and when the temperature of the reformer is higher than the upper limit of the operating temperature of the reformer, And controlling the temperature of the reformer by supplying the heated heating medium through the heat exchanger of the reformer to the reformer. The method of claim 1, The fruit medium is a control method of a fuel cell system, characterized in that (Water). A reformer for emitting reformed gas; A stack for generating energy by receiving the reformed gas generated by the reformer; And A circulating heating circuit provided between the reformer and the stack to increase the temperature of the stack by using heat generated by the reformer at initial startup, The circulating heating circuit, And a cooling plate channel for supplying the fruit medium from the reformer to the stack, and a circulation channel for returning the fruit object from the stack to the reformer. The method of claim 19, The cooling plate flow path, A fuel cell system provided between the heat exchanger provided in the reformer and the cooling plate provided in the stack. The method of claim 19, The cooling plate flow path, A fuel cell system provided between the heat exchanger provided in the reformer and the coolant reservoir provided in the stack. The method of claim 19, The cooling plate flow path, And a heat exchanger provided between the reformer and a cooling plate of the stack, and a fuel cell system provided between the heat exchanger and a coolant reservoir provided in the stack. The method of claim 19, The cooling plate flow passage is provided with a valve for controlling the supply of the fruit object, And a valve for controlling circulation of the fruit object in the circulation passage. The method of claim 19, The cooling plate provided in the stack is provided with a drain pipe extending outward to induce drainage of the fruit material stored in the cooling plate. The drain pipe is provided with a valve for controlling the drainage of the heat medium. The method of claim 19, The reformer is provided with a reformer, And a flow path for supplying the fruit medium at room temperature to the reformer and a flow path for supplying the fruit object branched and heated in the cooling plate flow path to the reformer.

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