KR20090113639A - Fuel cell system and control method thereof - Google Patents

Abstract

PURPOSE: A fuel cell system and a control method thereof are provided to raise temperature economically and rapidly until a stack of the fuel cell system can perform normal operation by heating a stack of the fuel cell system through a heat medium using heat energy generated from a carbon monoxide remover. CONSTITUTION: A fuel cell system comprises: a forming device(20) which generates reformed gas and includes a reformer(23) and a carbon monoxide remover; and a stack(30) which generates energy by receiving the reformed gas generated from the reformer. A control method of a fuel cell system comprises initial startup and normal startup. The initial startup heats a heat medium using at least one between heat energy generated as a reformer is operated and heat energy generated as the CO gas removal device is operated. The normal startup increases the stack to the normal operation temperature using the heated heat medium.

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 to a stack of a fuel cell system by applying a method of heating a stack of a fuel cell system with a heated heating medium using heat energy generated from a carbon monoxide remover. The present invention relates to a fuel cell system capable of raising the temperature economically and quickly to a state in which normal operation is possible, and a control method thereof.

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 system 110 does not reach a temperature for normal operation continues. do. 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 apply a method of heating the stack of the fuel cell system with the heating medium heated by using the heat energy generated in the carbon monoxide eliminator is a normal stack of the fuel cell system It is to raise the temperature economically and quickly until the operation is possible.

In the control method of the fuel cell system comprising a reformer for generating a reformed gas, including a reformer and a carbon monoxide remover, and a stack for generating energy by receiving the reformed gas generated from the reformer, After operating the reformer, the fruit is heated using at least one of thermal energy generated as the reformer is operated and thermal energy generated as the carbon monoxide remover is operated, and the stack is heated using the heated fruit media. It is achieved by the control method of the fuel cell system including an initial start to increase the temperature to the normal operating temperature, and a normal start to supply the reformed gas to the stack after the stack reaches the normal operating temperature.

The initial startup may include a first operation for supplying the heated fruit material to the stack, and the fruit material supplied to the stack through a circulating heating circuit provided between the reformer and the stack. It is preferred to include a second startup to heat the stack by allowing it to be circulated by a funnel.

In the first operation, the heated heating medium may be supplied to at least one of a cooling plate of the stack and a 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.

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.

The second operation is to supply the gas generated through the reformer and the shift reactor with the air to the carbon monoxide remover to operate the carbon monoxide remover, and the heat energy generated by the operation of the carbon monoxide remover to the heat exchanger of the reformer. It is preferable to supply.

In the initial start-up, 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, the fruit is not heated to the reformer to supply the reformer. It is possible to adjust the temperature of the.

In addition, the object is 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, carbon monoxide remover for reducing the content of carbon monoxide is provided, It can also be achieved by a fuel cell system for supplying thermal energy generated in the carbon monoxide eliminator to the reformer.

The reformer is provided with a heat exchanger, it is possible to supply the heat energy generated in the carbon monoxide remover to the heat exchanger.

At least one of the outer surfaces of the carbon monoxide remover is provided to be in surface contact with at least one of the outer surfaces of the heat exchanger, and the heat energy may be supplied through the contact surface in surface contact.

The fuel cell system and its control method according to the present invention apply a method of heating the stack of the fuel cell system with a heated heating medium using heat energy generated from the carbon monoxide remover until the stack of the fuel cell system can be operated normally. It can raise the temperature economically and quickly.

In addition, the fuel cell system and its control method according to the present invention can increase the temperature of the stack economically and quickly by applying a circulating heating circuit.

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 an embodiment of the present invention.

As shown in the drawing, the fuel cell system 10 according to an exemplary embodiment of the present invention includes a reformer 20 in which a reforming reaction proceeds, a stack 30 for generating electricity, and a coolant. The cooling liquid reservoir 40, the circulation 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 And a cooling plate passage 72 for supplying the cooling plate 36 and a heat supply path 180 provided between the carbon monoxide remover 29 and the heat exchanger 24 of the reformer 20.

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 exhaust gas 74 generated from the heating burner 22 is discharged to the outside after transferring the heat energy to the heat exchanger 24, the heat energy transferred to the heat exchanger 24 heats the water 64, the fruit medium supplied. do.

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, the air 66 and the 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 continues to heat 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 100 degrees Celsius or more, which is the shift reactor set temperature, by receiving heat from thermal by-products such as steam due to the heating of the reformer 23. When the shift reactor 26 is lower than the shift reactor set temperature, the shift reactor 26 passes through the heat exchanger 24 and the shift reactor 26 to transfer thermal energy to discharge the gas having a lower temperature. 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 carbon monoxide remover 29 through the shift reactor 26 and the mixer 27.

The mixer 27 is supplied with the gas generated in the shift reactor 26 when the second startup (one dashed line) and the normal startup proceed during the initial startup. The mixer 27 mixes the gas 66 supplied from the shift reactor 26 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.

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 + 47 kcal / mol

H ₂ + 0.5 O ₂ ↔ H ₂ 0 + 68 kcal / mol

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. Passing through the carbon monoxide remover 29, the content of carbon monoxide is reduced to less than 10 parts per million (ppm). When the temperature of the stack 30 is in the second starting (single dashed line) state in which the stack operating temperature is not reached, the above-described reaction equation proceeds and complete combustion occurs by adjusting the amount of air supplied to the mixer 27. At the same time, the thermal energy generated by the carbon monoxide remover 29 is provided to the heat exchanger 24. Thermal energy is heat of reaction generated when the reaction proceeds in the forward direction. That is, the reaction in the forward direction in the carbon monoxide remover 29 is an exothermic reaction, and a large amount of thermal energy is generated during the exothermic reaction. Carbon dioxide and water generated during the exothermic reaction are discharged to the outside, and the generated heat energy is supplied to the heat exchanger 24 through the heat supply path 180. In the present embodiment, the heat supply path 180 is represented by a supply path separately provided between the carbon monoxide remover 29 and the heat exchanger 24, but the carbon monoxide remover 29 is in surface contact with the outside of the heat exchanger 24 and closely adhered thereto. When provided, since the thermal energy is supplied from the carbon monoxide remover 29 to the heat exchanger 24 through the outer surface of the carbon monoxide remover 29 and the heat exchanger 24 provided in contact with each other, a separate supply path is not required. On the other hand, in the normal startup (solid line) state, 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 hot steam is deprived of 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 energy generated by the heating burner 22 and the reformer 23 in the heat exchanger 24 and rises in temperature, passes through the second valve 92 to reach the separator 78.

In the separator 78, the cooling plate flow path 72 is branched into the first cooling plate flow path 74 and the second cooling plate flow path 76. The separator 78 supplies the water 64 heated only in the direction of the first cooling plate flow path 74 by the control signal of the controller (not shown), or the water 64 heated only in the direction of the second cooling plate flow path 76. ) Or heated water 64 to both the first and second cooling plate flow paths 74 and 76. The first cooling plate flow path 74 directly supplies the hot water heated by the cooling plate 36, and the second cooling plate flow path 76 supplies the hot water heated by the cooling liquid reservoir 76. The heated hot water supplied to the cooling liquid reservoir 76 is supplied to the cooling plate 36 through the cooling liquid flow path 73 according to whether the ninth valve 99 is opened or closed according to the control signal. The heated water 64 supplied along the first and second cooling plate flow paths 74 and 76 transfers thermal energy to the stack 30 in the cooling plate 36 and raises the temperature of the 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, and even if the ion conductivity of the water existing in the cooling plate 36 is higher than the reference value, the water stored in the cooling plate 36 can be discharged. 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 an 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, second, and ninth valves 91, 92, and 99 and the separator 78 are controlled to supply the heat medium to the coolant reservoir 40. (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, opening and closing of the first, second, third and ninth valves 91, 92, 93, and 99 to continuously increase the temperature of the stack 30 even after the water level inside the cooling plate 36 reaches the target upper limit. It is possible to control and to discharge the hot water stored in the supply to the cooling plate 36 and receive new 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, the first, second, third, and nineth valves 91, 92, 93, 99 are used to continuously raise the temperature of the stack 30 even after the water level inside the cooling plate 36 reaches the target upper limit. It is possible to control the opening and closing of the hot water is supplied to the cooling plate 36 to discharge the stored water and at the same time receive new water.

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.

When the temperature of the stack 30 is lower than the stack operating temperature, the mixer 27 is opened to supply the mixed gas mixed with air to the carbon monoxide remover 29 (S110). At this time, in order to completely burn the gas passed through the shift reactor supplied from the carbon monoxide remover 29, the amount of air is adjusted to supply the mixed gas to the mixer 27. When the mixed gas is supplied to the carbon monoxide remover 29, an exothermic reaction is started in the carbon monoxide remover 29 and thermal energy is generated.

The thermal energy generated by the carbon monoxide remover 29 is supplied to the heat exchanger 24 (S120). Thermal energy is supplied to the heat supply path 180. On the other hand, when the carbon monoxide remover 29 and the heat exchanger 24 are in close contact with each other, even if a separate heat supply path 180 is not provided, heat energy may be transmitted through the contact surface.

Blocking the first valve 91 and opens the fifth valve (95) (S130). 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, if 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 thermal 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, which is an economical method of rapidly increasing 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 (S140). 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.

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 startup (solid line) of the fuel cell system 10 is initiated by blocking the fourth and fifth valves 94 and 95 (S160). 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 for directly supplying the room temperature water 64 to the reformer 23 is shut off, so that the temperature difference between the room temperature water 64 and the high temperature reformer 23 is reduced. There is no room for a significant change in temperature.

While blocking the fourth and fifth valves 94 and 95, the second valve 92 is blocked and the first, seventh and eighth valves 91, 97, and 98 are opened (S170). 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 (S180).

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.

In the above-described embodiment, the case in which the heating through the carbon monoxide remover and the heating through the reformer are performed at the same time is described. However, the heating through the carbon monoxide remover and the heating through the reformer may be selectively performed as necessary.

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 an embodiment of the present invention.

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

* 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

180: heat supply path

Claims (10)

In the control method of a fuel cell system comprising a reformer for generating a reformed gas, including a reformer and a carbon monoxide remover, and a stack for generating energy by receiving the reformed gas generated from the reformer, After operating the reformer, the fruit is heated using at least one of thermal energy generated as the reformer is operated and thermal energy generated as the carbon monoxide remover is operated, and the stack is heated using the heated fruit media. Initial startup to raise the temperature to normal operating temperature, 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 start of heating the stack by causing the fruit material supplied to the stack to circulate through a circulating heating circuit provided between the reformer and the stack. The method of claim 2, The first start is, The heated heating medium is supplied to at least one of the cooling plate of the stack and the cooling liquid reservoir provided in the stack. 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, 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 shift reactor set temperature. The method of claim 2, The second start, Supplying the gas generated through the reformer and the shift reactor to the carbon monoxide remover together with air to operate the carbon monoxide remover, And supplying heat energy generated by the operation of the carbon monoxide remover to the heat exchanger of the reformer. The method of claim 1, 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. A fuel cell system including a reformer for generating reformed gas and a stack for generating energy by receiving the reformed gas generated from the reformer, Carbon monoxide remover is provided to reduce the content of carbon monoxide, A fuel cell system for supplying the heat energy generated in the carbon monoxide remover to the reformer. The method of claim 8, The reformer is provided with a heat exchanger, A fuel cell system for supplying the heat energy generated in the carbon monoxide remover to the heat exchanger. The method of claim 9, At least one surface of the outer surface of the carbon monoxide remover is provided to be in surface contact with at least one surface of the outer surface of the heat exchanger, The supply of thermal energy, A fuel cell system comprising a contact surface in contact with the surface.

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