KR102580540B1 - Fuel cell system - Google Patents

Abstract

The present invention relates to fuel cell systems. A fuel cell system according to an embodiment of the present invention includes a stack that generates electricity; A blower that supplies air to the stack; a humidifier disposed between the stack and the blower, supplying moisture to the air discharged from the blower and discharging the air discharged from the stack to the outside; a first switching valve disposed at the front of the blower and supplying external air or air discharged from the stack to the blower; a first purge passage connecting the stack discharge end and the first switching valve and guiding air discharged from the stack to the first switching valve; a second switching valve disposed at a rear end of the humidifying device and supplying air discharged from the humidifying device to the stack or re-supplying the air discharged from the humidifying device to the humidifying device; a second purge passage connecting the second switching valve and the stack discharge end and guiding the air discharged from the humidifying device to the humidifying device; and a purge valve disposed at the discharge end of the stack and guiding air discharged from the stack to the first purge passage.

Description

Fuel cell system{FUEL CELL SYSTEM}

The present invention relates to a fuel cell system, and more specifically, to a fuel cell system that removes oxygen remaining in the stack after termination of power generation operation.

A fuel cell system is a power generation system that generates electrical energy by electrochemically reacting hydrogen contained in hydrocarbon-based materials, such as methanol, ethanol, and natural gas, with oxygen.

A general fuel cell system, similar to Prior Art 1 (Korean Patent Publication No. 10-2012-0071288), includes a fuel processing device for reforming fuel containing hydrogen atoms into hydrogen gas, and a fuel processing device. It is provided with a stack that generates electrical energy using hydrogen gas supplied from. In addition, the fuel cell system may be further equipped with a heat exchanger and cooling water piping for cooling the stack and recovering heat, and a power conversion device for converting the produced direct current power into alternating current power.

In the case of prior art 1 (Korean Patent Publication No. 10-2012-0071288), there is a problem that the lifespan of the stack is reduced as oxygen remaining in the cathode electrode part of the stack reacts after the power generation operation ends.

Meanwhile, in order to remove oxygen remaining in the stack after the end of power generation operation, prior art 2 (Korean Patent Publication No. 10-2011-0019274) uses hydrogen purge in the hydrogen purge line of the fuel supply system that supplies fuel to the stack. A separate branch valve is installed that branches off from the valve, and the hydrogen passing through the branch valve at the end of power generation operation is disclosed to purge the cathode electrode part of the stack through the air supply line. However, the cathode ) Anode off gas (AOG) must be additionally generated and supplied to supply to the electrode part, and the life of the stack may be shortened due to heat generation due to the chemical reaction between residual oxygen and hydrogen in the cathode electrode part. There is a problem that is being reduced.

Therefore, there is a need for research to prevent a decrease in the lifespan of the stack by removing oxygen remaining in the cathode electrode part of the stack after the power generation operation ends.

KR 10-2012-0071288 A KR 10-2011-0019274 A

The present invention aims to solve the above-mentioned problems and other problems.

Another object of the present invention is to provide a fuel cell system that performs a purge operation to remove oxygen remaining in the cathode electrode part of the stack after the power generation operation is completed.

Another object of the present invention is to provide a fuel cell system that can reduce system maintenance costs.

The problems of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

In order to achieve the above object, a fuel cell system according to an embodiment of the present invention includes a stack that generates electricity; A blower that supplies air to the stack; a humidifier disposed between the stack and the blower, supplying moisture to the air discharged from the blower and discharging the air discharged from the stack to the outside; a first switching valve disposed at the front of the blower and supplying external air or air discharged from the stack to the blower; a first purge passage connecting the stack discharge end and the first switching valve and guiding air discharged from the stack to the first switching valve; a second switching valve disposed at a rear end of the humidifying device and supplying air discharged from the humidifying device to the stack or re-supplying the air discharged from the humidifying device to the humidifying device; a second purge passage connecting the second switching valve and the stack discharge end and guiding the air discharged from the humidifying device to the humidifying device; and a purge valve disposed at the discharge end of the stack and guiding air discharged from the stack to the first purge passage.

It includes a control unit that controls switching of the first switching valve and the second switching valve, opening and closing of the purge valve, and operation of the blower according to the operation mode, and the control unit controls the first purge flow path and the The first switching valve is adjusted so that the blower is connected, the second switching valve is adjusted so that the humidifier and the second purge passage are connected, and the air discharged from the stack flows into the first purge passage. The purge valve may be closed and the blower may be operated to remove air remaining in the stack.

It is disposed in the first purge passage and includes a pressure gauge that measures the pressure of the first purge passage, and the control unit is configured to allow external air to flow into the first purge passage when the pressure of the first purge passage detected by the pressure gauge is below a set value. The first switching valve can be adjusted so that supply is supplied to the blower.

The set value may be atmospheric pressure or a pressure more negative than atmospheric pressure.

The purge valve may be located between a branch point of the first purge passage and a branch point of the second purge passage.

A branch point of the first purge passage may be located closer to the stack than a branch point of the second purge passage.

It includes a control unit that controls the first switching valve and the second switching valve according to the operation mode, and controls opening and closing of the purge valve and operation of the blower, wherein the control unit directs external air to the blower during power generation operation. The first switching valve can be adjusted to supply air, the second switching valve can be switched to connect the humidifier and the stack, and the blower can be operated to supply external air to the stack.

It is disposed at the rear end of the blower and includes an air flow meter that measures the air flow rate supplied to the stack, and the control unit, when the air flow rate measured by the air flow meter is less than a set value, the first purge flow path and the The first switching valve is adjusted so that the blower is connected, the second switching valve is adjusted so that the humidifier and the second purge passage are connected, and the air discharged from the stack flows into the first purge passage. You can enter purge operation by closing the purge valve.

Stacks that generate electricity; A blower that supplies air to the stack; a humidifier that supplies moisture to the air discharged from the blower and discharges the air discharged from the stack to the outside; a purge valve that guides air discharged from the stack to the blower; a first switching valve that supplies external air or air discharged from the stack to the blower; and a second switching valve for supplying air discharged from the humidifying device to the stack or re-supplying the air discharged from the humidifying device, wherein air is supplied to the stack through the blower to performing a power generation operation to generate electricity; And at the end of the power generation operation, it may include performing a purge operation to remove air remaining in the stack by adjusting the first switching valve, the second switching valve, and the purge valve.

The step of performing the power generation operation includes switching the first switching valve so that the air inflow path and the blower are connected, switching the second switching valve so that the humidifier and the stack are connected, and operating the blower. External air can be supplied to the stack.

It is disposed at the rear end of the blower and includes an air flow meter that measures the air flow rate supplied to the stack, and when a power generation operation end signal is received from the input unit or the air flow rate measured by the air flow meter is less than the set value, power generation is performed. You can end operation and perform purge operation.

The step of performing the purge operation includes adjusting the first switching valve so that the first purge flow path and the blower are connected, adjusting the second switching valve so that the humidifier and the second purge flow path are connected, and controlling the stack. The purge valve can be closed so that the air discharged from flows into the first purge passage.

When the pressure of the first purge passage detected by the pressure gauge is below the set value, external air can be supplied to the blower by adjusting the first switching valve so that the air inlet passage is connected to the blower.

The set value may be atmospheric pressure or a pressure more negative than atmospheric pressure.

Specific details of other embodiments are included in the detailed description and drawings.

According to various embodiments of the present invention, a purge operation is performed after the power generation operation is completed to block air inflow into the stack, and oxygen remaining in the stack is discharged to the outside through a blower to prevent oxidation of the cathode electrode portion. This can prevent a decrease in the lifespan of the stack due to

In addition, according to various embodiments of the present invention, as the service life of the stack increases due to the purge operation, system maintenance costs are reduced, thereby securing economic efficiency.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a schematic diagram of the configuration of a fuel processing device according to an embodiment of the present invention.
Figure 2 is a configuration diagram of a fuel cell system according to an embodiment of the present invention.
Figure 3 is a diagram of configurations for performing a purge operation of a fuel cell system according to an embodiment of the present invention.
Figure 4 is a diagram for explaining the power generation operation of a fuel cell system according to an embodiment of the present invention.
Figure 5 is a diagram for explaining a purge operation of a fuel cell system according to an embodiment of the present invention.
Figure 6 is a control block diagram of a fuel cell system according to an embodiment of the present invention.
7 and 8 are flowcharts of a control method of a fuel cell system according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. In the drawings, parts not related to the description are omitted in order to clearly and briefly explain the present invention, and identical or extremely similar parts are denoted by the same drawing reference numerals throughout the specification.

The suffixes “module” and “part” for components used in the following description are simply given in consideration of the ease of writing this specification, and do not in themselves give any particularly important meaning or role. Accordingly, the terms “module” and “unit” may be used interchangeably.

In this application, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Additionally, in this specification, terms such as first and second may be used to describe various elements, but these elements are not limited by these terms. These terms may be used only to distinguish one element from another.

1 is a schematic diagram of the configuration of a fuel processing device according to an embodiment of the present invention.

Referring to FIG. 1, the fuel processing device 10 includes a desulfurizer 110, a burner 120, a steam generator 130, a reformer 140, a first reactor 150, and/or a second reactor 160. ) may include. The fuel processing device 10 may further include at least one mixer 111 and 112.

The desulfurizer 110 may perform a desulfurization process to remove sulfur compounds contained in fuel gas. For example, the desulfurizer 110 may have an adsorbent therein. At this time, sulfur compounds contained in the fuel gas passing through the desulfurizer 110 may be adsorbed on the adsorbent.

The adsorbent may be composed of metal oxide, zeolite, activated carbon, etc.

The desulfurizer 110 may further include a filter that removes foreign substances contained in the fuel gas.

The burner 120 may supply heat to the reformer 140 to promote the reforming reaction in the reformer 140. For example, the fuel gas discharged from the desulfurizer 110 and the air introduced from the outside may be mixed in the first mixer 111 and supplied to the burner 120. At this time, the burner 120 may generate combustion heat by burning a mixed gas of fuel gas and air. At this time, the internal temperature of the reformer 140 can be maintained at an appropriate temperature (e.g., 800°C) by the heat supplied from the burner 120.

Meanwhile, the exhaust gas generated in the burner 120 by combustion of the mixed gas may be discharged to the outside of the fuel processing device 10.

The steam generator 130 can vaporize water and discharge it as steam. For example, the steam generator 130 may vaporize water by absorbing heat from the exhaust gas generated by the burner 120, the first reactor 150, and/or the second reactor 160.

The steam generator 130 may be placed adjacent to a pipe through which exhaust gas discharged from the first reactor 150, the second reactor 160, and/or the burner 120 flows.

The reformer 140 may perform a reforming process to generate hydrogen gas from fuel gas from which sulfur compounds have been removed, using a catalyst. For example, the fuel gas discharged from the desulfurizer 110 and the water vapor discharged from the steam generator 130 may be mixed in the second mixer 112 and supplied to the reformer 140. At this time, when the fuel gas and water vapor supplied to the reformer 140 undergo a reforming reaction within the reformer 140, hydrogen gas may be generated.

The first reactor 150 can reduce carbon monoxide generated by the reforming reaction among the components contained in the gas discharged from the reformer 140. For example, carbon monoxide contained in the gas discharged from the reformer 140 may react with water vapor inside the first reactor 150 to generate carbon dioxide and hydrogen. At this time, the internal temperature of the first reactor 150 may be lower than the internal temperature of the reformer 140 and higher than room temperature (e.g., 200°C).

The first reactor 150 may be called a shift reactor.

The second reactor 160 can reduce carbon monoxide remaining among the components contained in the gas discharged from the first reactor 150. For example, a preferential oxidation (PROX) reaction may occur in which carbon monoxide contained in the gas discharged from the first reactor 150 reacts with oxygen inside the second reactor 160.

Meanwhile, in the case of a selective oxidation reaction, a large amount of oxygen is required, so additional supply of air is required, and the hydrogen is diluted by the additionally supplied air, which has the disadvantage of reducing the concentration of hydrogen supplied to the stack. Therefore, to overcome these disadvantages, a selective methanation reaction in which carbon monoxide and hydrogen react can be utilized.

Meanwhile, the gas discharged from the fuel processing device 10 through the reformer 140, the first reactor 150, and/or the second reactor 160 may be called reformed gas.

The stack 20 can generate electrical energy by causing an electrochemical reaction in the reformed gas supplied from the fuel processing device 10.

The stack 20 may be constructed by stacking single cells in which an electrochemical reaction occurs.

A single cell may be composed of a membrane-electrode assembly (MEA) in which a fuel electrode and an air electrode are arranged around an electrolyte membrane, a separator, etc. At the fuel electrode of the membrane-electrode assembly, hydrogen can be separated into hydrogen ions and electrons by a catalyst to generate electricity, and at the air electrode of the membrane-electrode assembly, hydrogen ions and electrons can combine with oxygen to generate water.

The stack 20 may further include a stack heat exchanger (not shown) that dissipates heat generated during the electrochemical reaction. A stack heat exchanger may be a heat exchanger that uses water as a refrigerant. For example, the coolant supplied to the stack heat exchanger can absorb heat generated during the electrochemical reaction, and the coolant whose temperature rises due to the absorbed heat is used in the stack heat exchanger. It may be discharged to the outside of the body.

Figure 2 is a configuration diagram of a fuel cell system including a fuel processing device according to an embodiment of the present invention. Figure 3 is a diagram of configurations for performing a purge operation according to an embodiment of the present invention.

Referring to FIGS. 2 and 3, the fuel cell system 1 may include a fuel processing unit (I), a power generation unit (II), a coolant circulation unit (III), and/or a heat recovery unit (IV).

The fuel processing unit (I) includes a fuel processing device 10, a fuel valve 30 that regulates the flow of fuel gas supplied to the fuel processing device 10, and a first blower that flows air into the fuel processing device 10. (71), etc. may be included.

The power generation unit (II) is a stack (20a, 20b), a reformed gas heat exchanger (21) in which heat exchange of the reformed gas discharged from the fuel processing device (10) occurs, and a reformed gas heat exchanger (21) in which heat exchange of the reformed gas discharged from the fuel processing device (10) occurs, and the stack (20a, 20b) discharges unreacted gas. AOG heat exchanger (22) in which gas heat exchange occurs, a humidifier (23) that supplies moisture to the air supplied to the stacks (20a, 20b), and a second blower (72) that flows air to the stacks (20a, 20b) It may include etc. Here, the gas discharged from the stacks 20a and 20b without reacting may be referred to as anode off gas (AOG). In one embodiment of the present invention, the fuel cell system 1 is described as having two stacks 20a and 20b, but is not limited thereto.

The cooling water circulation unit (III) includes a water supply tank (13) for storing water generated in the fuel cell system (1), a water pump (38) for flowing water to the fuel processing device (10), and a fuel processing device (10). ) may include a water supply valve (39) that controls the flow of water supplied to the water supply valve (39), a cooling water pump (43) that flows water to the reforming gas heat exchanger (21), etc.

The heat recovery unit (IV) may include a heat recovery tank 15 that stores water used for heat exchange, a hot water pump 48 that flows water stored in the heat recovery tank 15 to the outside of the heat recovery tank 15, etc. .

The fuel valve 30 may be disposed in the fuel supply passage 101 through which fuel gas supplied to the fuel processing device 10 flows. Corresponding to the degree of opening of the fuel valve 30, the flow rate of fuel gas supplied to the fuel processing device 10 may be adjusted. For example, the fuel valve 30 may block the fuel supply passage 101 so that the supply of fuel gas to the fuel processing device 10 is stopped.

A first fuel flow meter 51 that detects the flow rate of fuel gas flowing in the fuel supply passage 101 may be disposed in the fuel supply passage 101.

The first blower 71 may be connected to the first external air inflow passage 201 and the fuel-side air supply passage 202. The first blower 71 can flow air introduced from the outside through the first external air inlet passage 201 to the fuel processing device 10 through the fuel-side air supply passage 202.

Air flowing into the fuel processing device 10 through the fuel-side air supply passage 202 may be supplied to the burner 120 of the fuel processing device 10. For example, the air flowing into the fuel processing device 10 may be mixed with the fuel gas discharged from the desulfurizer 110 in the first mixer 111 and then supplied to the burner 120.

In the first external air inflow passage 201, an air filter 91 that removes foreign substances such as dust contained in the air and/or a first air side check valve 81 that limits the flow direction of air may be disposed. there is.

The fuel processing unit (I) may include a first internal gas flow path 102 through which the fuel gas discharged from the desulfurizer 110 flows to the reformer 140. The first internal gas passage 102 includes a proportional control valve 31, an internal fuel valve 32 that regulates the flow of fuel gas flowing into the reformer 140, and a proportional control valve 32 that controls the flow of fuel gas flowing into the internal gas passage 102. A second fuel flow meter 52 that detects the flow rate, a fuel side check valve 83 that limits the flow direction of the fuel gas flowing in the internal gas passage 102, and/or a sulfur detection device 94 may be disposed. there is.

The proportional control valve 31 can control the flow rate and pressure of the fuel gas discharged from the desulfurizer 110 and flowing into the reformer 140 through internal/external feedback in an electrical control manner.

The sulfur detection device 94 can detect sulfur contained in the fuel gas discharged from the desulfurizer 110. The sulfur detection device 94 may include an indicator that changes color in response to sulfur compounds not removed by the adsorbent of the desulfurizer 110. Here, the indicator may include phenolphthalein, a molybdenum compound, etc.

The fuel processing unit (I) may include a second internal gas flow path 103 through which the fuel gas discharged from the desulfurizer 110 flows to the burner 120. The burner 120 can use the fuel gas flowing in through the second internal gas passage 103 for combustion.

The first internal gas passage 102 and the second internal gas passage 103 may be in communication with each other.

The fuel processing device 10 may be connected to the water supply passage 303 through which water discharged from the water supply tank 13 flows. In the water supply passage 303, a water pump 38, a water supply valve 39 that regulates the flow of water, and/or a water flow meter 54 that detects the flow rate of water flowing in the water supply passage 303 will be disposed. You can.

The exhaust gas generated in the burner 120 of the fuel processing device 10 may be discharged from the fuel processing device 10 through the exhaust gas discharge passage 210.

The fuel processing device 10 may be connected to the reformed gas discharge passage 104. The reformed gas discharged from the fuel processing device 10 may flow through the reformed gas discharge passage 104.

The reformed gas discharge passage 104 may be connected to the reformed gas heat exchanger 21 in which heat exchange of the reformed gas occurs. A reformed gas valve 33 that regulates the flow of reformed gas flowing into the reformed gas heat exchanger 21 may be disposed in the reformed gas discharge passage 104.

The reformed gas discharge passage 104 may communicate with a bypass passage 105 through which the reformed gas discharged from the fuel processing device 10 flows to the fuel processing device 10. The bypass passage 105 may be connected to the fuel processing device 10. The reformed gas flowing into the fuel processing device 10 through the bypass passage 105 may be used as fuel for combustion in the burner 120. A bypass valve 34 that regulates the flow of reformed gas flowing into the fuel processing device 10 may be disposed in the bypass passage 105.

The reformed gas heat exchanger 21 may be connected to the reformed gas discharge passage 104 through which the reformed gas discharged from the fuel processing device 10 flows. The reforming gas heat exchanger 21 may be connected to the cooling water supply passage 304 through which water discharged from the water supply tank 13 flows. The reformed gas heat exchanger 21 can exchange heat between the reformed gas flowing in through the reformed gas discharge passage 104 and the water supplied through the cooling water supply passage 304.

The cooling water supply passage 304 includes a cooling water pump 43 that flows water stored in the water supply tank 13 to the reforming gas heat exchanger 21, and/or detects the flow rate of water flowing in the cooling water supply passage 304. A coolant flow meter 56 may be disposed.

The reformed gas heat exchanger 21 may be connected to the stack gas supply passage 106. The reformed gas discharged from the reformed gas heat exchanger 21 is sent to the stacks 20a and 20b through the stack gas supply passage 106. It can be fluid.

A reformed gas moisture removal device 61 that adjusts the amount of moisture contained in the reformed gas may be disposed in the stack gas supply passage 106. The reformed gas flowing into the reformed gas moisture removal device 61 may be discharged from the reformed gas moisture removal device 61 after the moisture is removed.

Condensed water generated in the reformed gas moisture removal device 61 may be discharged from the reformed gas moisture removal device 61 and flow into the first water recovery passage 309. A first water recovery valve 44 that regulates the flow of water may be disposed in the first water recovery passage 309.

The stacks 20a and 20b can generate electrical energy by causing an electrochemical reaction in the reformed gas flowing in through the stack gas supply passage 106. In one embodiment, when the fuel cell system 1 is provided with a plurality of stacks 20a and 20b, the reformed gas discharged without reacting from the first stack 20a is additionally electrochemically processed in the second stack 20b. may cause a reaction.

The second blower 72 may be connected to the second external air inflow passage 203 connected to the first external air inflow passage 201 and the stack-side air supply passage 204. The second external air inflow passage 203 may be connected to the rear end of the air filter 91. The second blower 72 can cause air flowing in through the second external air inflow passage 203 to flow toward the stack 20 through the stack-side air supply passage 204.

The second blower 72 may include an impeller 73 that pressurizes air as it rotates, and a motor 74 that transmits rotational force through a rotation shaft connected to the impeller 73.

A second air-side check valve 82 that limits the flow direction of air may be disposed in the second external air inflow passage 203.

A first switching valve 223 that switches the air flow path according to the operation mode may be disposed in the second external air inflow path 203. For example, the first switching valve 223 may be a three-way valve.

The first switching valve 223 switches the air flow path to supply air introduced through the second external air inlet flow path 203 to the second blower 72 or to control air discharged from the stack 20. 2 Can be supplied with blower (72). For example, the first inlet end of the first switching valve 223 is connected to the second external air inlet flow path 203, and the second inlet end of the first switching valve 223 is connected to the first purge flow path ( 221).

A pressure gauge 57 that detects the pressure of air flowing through the first purge passage 221 may be disposed in the first purge passage 221.

An air flow meter 53 that detects the flow rate of air flowing in the stack-side air supply passage 204 may be disposed in the stack-side air supply passage 204.

The humidifier 23 can supply moisture to the air flowing in through the stack-side air inlet passage 204 and discharge air containing moisture through the stack-side air supply passage 205.

A stack-side air supply valve 36 that regulates the flow of air supplied to the stack 20 may be disposed in the stack-side air supply passage 205.

A second switching valve 224 that switches the air flow path according to the operation mode may be disposed in the stack-side air supply passage 205. For example, the second switching valve 224 may be a three-way valve.

The second switching valve 224 can switch the air flow path to supply the air discharged from the humidifying device 23 to the stack 20 or supply it back to the humidifying device 23. The first discharge end of the second switching valve 224 may be connected to the stack-side air supply passage 205, and the second discharge end of the second switching valve 224 may be connected to the second purge passage 222. there is.

The stack-side air supply passage 205 may be connected to the individual supply passages 206 and 207 corresponding to the stacks 20a and 20b, respectively. Air flowing through the stack-side air supply passage 205 may be supplied to the stacks 20a and 20b through the individual supply passages 206 and 207.

A plurality of stacks 20a and 20b may be connected to each other by a gas connection passage 107. The reformed gas discharged from the first stack 20a without reacting may flow into the second stack 20b through the gas connection passage 107.

An additional moisture removal device 62 may be disposed in the gas connection passage 107 to remove water generated by condensation of the reformed gas while passing through the first stack 20a.

The water generated in the additional moisture removal device 62 may be discharged from the additional moisture removal device 62 and flow into the second water recovery passage 310. A second water recovery valve 45 that regulates the flow of water may be disposed in the second water recovery passage 310. The second water recovery passage 310 may be connected to the first water recovery passage 309.

The anode exhaust gas (AOG) discharged without reacting from the stacks 20a and 20b may flow through the stack gas discharge passage 108.

The AOG heat exchanger 22 may be connected to the stack gas discharge passage 108 through which the anode exhaust gas (AOG) discharged from the stacks 20a and 20b flows. The AOG heat exchanger 22 may be connected to the hot water supply passage 313 through which water discharged from the heat recovery tank 15 flows. The AOG heat exchanger 22 can exchange heat between anode exhaust gas (AOG) flowing in through the stack gas discharge passage 108 and water supplied through the hot water supply passage 313.

In the hot water supply passage 313, there is a hot water pump 48 that flows the water stored in the heat recovery tank 15 to the AOG heat exchanger 22 and/or a hot water flow meter that detects the flow rate of water flowing in the hot water supply passage 313. (55) can be placed.

The AOG heat exchanger 22 may be connected to the AOG supply passage 109 and may discharge heat-exchanged anode exhaust gas (AOG) through the AOG supply passage 109. The anode exhaust gas (AOG) discharged from the AOG heat exchanger 22 may flow to the fuel processing device 10 through the AOG supply passage 109. The anode exhaust gas (AOG) supplied to the fuel processing device 10 through the AOG supply passage 109 can be used as fuel for combustion in the burner 120.

In the AOG supply passage 109, the flow of anode exhaust gas (AOG) supplied to the AOG moisture removal device 63 and/or the fuel processing device 10 controls the amount of moisture contained in the anode exhaust gas (AOG). An AOG valve 35 that regulates may be disposed. The anode exhaust gas (AOG) flowing into the AOG moisture removal device 63 may be discharged from the AOG moisture removal device 63 after the moisture is removed.

Condensed water generated in the AOG moisture removal device 63 may be discharged from the AOG moisture removal device 63 and flow through the third water recovery passage 311. A third water recovery valve 46 that regulates the flow of water may be disposed in the third water recovery passage 311. The third water recovery passage 311 may be connected to the first water recovery passage 309.

The stack-side air discharge passage 211 may be connected to the individual discharge passages 208 and 209 corresponding to the stacks 20a and 20b, respectively. Air discharged from the stacks 20a and 20b may flow into the stack-side air discharge passage 211 through the individual discharge passages 208 and 209. At this time, the air flowing through the stack-side air discharge passage 211 may contain moisture generated by the electrochemical reaction occurring in the stacks 20a and 20b.

A stack-side air discharge valve 37 that regulates the flow of air discharged from the stack 20 may be disposed in the stack-side air discharge passage 211.

The stack-side air discharge passage 211 is opened and closed depending on the operation mode to limit the flow direction of the air discharged from the stack 20 to the direction of the humidifier 23 or to discharge the stack-side air through the second purge passage 222. A purge valve 225 may be disposed to limit the flow direction of air flowing in the discharge passage 211 to the direction of the first purge passage 221.

The purge valve 225 may be located between the branch point (P1) of the first purge passage 221 and the junction point (P2) of the second purge passage 222. Here, the branch point P1 of the first purge passage 221 may be located upstream from the junction point P2 of the second purge passage 222 based on the air flow direction.

The stack side air discharge passage 211 may be connected to the humidifier 23. The humidifier 23 can supply moisture to the air flowing into the stack 20 using moisture contained in the air supplied through the stack-side air discharge passage 211. The air supplied to the humidifier 23 through the stack-side air discharge passage 211 may be discharged to the humidifier discharge passage 212 through the humidifier 23.

The water supply tank 13 may be connected to the water inflow passage 301 and may store water supplied through the water inflow passage 301. The water inflow passage 301 includes a first liquid filter 92 that removes foreign substances contained in water supplied from the outside and/or a water inlet valve 41 that regulates the flow of water flowing into the water supply tank 13. can be placed.

The water supply tank 13 may be connected to the water discharge passage 302, and may discharge at least a portion of the water stored in the water supply tank 13 to the outside through the water discharge passage 302. A water discharge valve 42 that regulates the flow of water discharged from the water supply tank 13 may be disposed in the water discharge passage 302.

The water supply tank 13 may be connected to the water storage passage 308 and may store water flowing through the water storage passage 308. For example, it is discharged from the reformed gas moisture removal device 61, the additional moisture removal device 62, the AOG moisture removal device 63, and/or the air moisture removal device 64 and passes through the third water recovery passage 311. Water flowing through the water may flow into the water supply tank 13 through the water storage passage 308. A second liquid filter 93 may be disposed in the water storage passage 308 to remove foreign substances contained in the water returned to the water supply tank 13.

At least some of the water stored in the water supply tank 13 may flow into the reforming gas heat exchanger 21 by the cooling water pump 43 and exchange heat with the reforming gas in the reforming gas heat exchanger 21. Water discharged from the reforming gas heat exchanger 21 may flow into the stacks 20a and 20b through the stack water supply passage 305.

Water flowing into the stacks 20a and 20b through the stack water supply passage 305 can cool the stacks 20a and 20b. The water flowing into the stacks 20a and 20b may flow along the stack heat exchanger (not shown) included in the stacks 20a and 20b, and may cause electrochemical reactions occurring in the stacks 20a and 20b. Can absorb heat.

A plurality of stacks 20a and 20b may be connected by a water connection passage 306. Water discharged from the first stack 20a may flow into the second stack 20b through the water connection passage 306.

Water discharged from the stacks 20a and 20b may flow into the coolant heat exchanger 24 through the stack water discharge passage 307. The cooling water heat exchanger 24 can exchange heat between water discharged from the stacks 20a and 20b and water discharged from the heat recovery tank 15. The water discharged from the stacks 20a and 20b may flow into the water storage passage 308 through the cooling water heat exchanger 24.

Water discharged from the heat recovery tank 15 by the hot water pump 48 may flow into the AOG heat exchanger 22 through the hot water supply passage 313. The water heat-exchanged with the anode exhaust gas (AOG) in the AOG heat exchanger 22 may be discharged to the first hot water circulation circuit 314.

The air heat exchanger 25 may be connected to the humidifier discharge passage 212 through which air discharged from the humidifier 23 flows. The air heat exchanger 25 may be connected to the first hot water circulation circuit 314 through which water discharged from the AOG heat exchanger 22 flows. The air heat exchanger 25 can heat exchange the air flowing in through the humidifier discharge passage 212 and the water flowing in through the first hot water circulation circuit 314.

The air heat-exchanged in the air heat exchanger 25 may be discharged from the air heat exchanger 25 through the air discharge passage 213. The air discharge passage 213 may be in communication with the exhaust gas discharge passage 210, and the exhaust gas flowing in the exhaust gas discharge passage 210 and the air flowing in the air discharge passage 213 may be mixed.

An air moisture removal device 64 may be disposed in the air discharge passage 213. The air moisture removal device 64 can control the amount of moisture contained in the air discharged to the outside. The air introduced into the air moisture removal device 64 may be discharged from the air moisture removal device 64 after the moisture is removed.

Condensed water generated in the air moisture removal device 64 may be discharged from the air moisture removal device 64 and flow through the fourth water recovery passage 312. A fourth water recovery valve 47 that regulates the flow of water may be disposed in the fourth water recovery passage 312. The fourth water recovery passage 312 may be connected to the water storage passage 308.

Water heat-exchanged in the air heat exchanger 25 may be discharged from the air heat exchanger 25 through the second hot water circulation passage 315. Water discharged from the air heat exchanger (25) may flow into the coolant heat exchanger (24) through the second hot water circulation passage (315).

The cooling water heat exchanger 24 can exchange heat between water flowing in through the stack water discharge passage 307 and water flowing in through the second hot water circulation passage 315.

The exhaust heat exchanger 26 may be connected to the exhaust gas discharge passage 210 through which exhaust gas flows. The exhaust heat exchanger 26 may be connected to the third hot water circulation passage 316 through which water discharged from the coolant heat exchanger 24 flows. The exhaust heat exchanger 26 can exchange heat between the exhaust gas flowing in through the exhaust gas discharge passage 210 and the water flowing in through the third hot water circulation passage 316.

The exhaust gas heat-exchanged in the exhaust heat exchanger 26 may be discharged to the exhaust passage 214, and the exhaust gas flowing in the exhaust passage 214 may be discharged to the outside.

Water heat exchanged in the exhaust heat exchanger 26 may be discharged to the hot water recovery passage 317, and water flowing in the hot water recovery passage 317 may flow into the heat recovery tank 15.

<Generation operation>

Figure 4 is a diagram for explaining the power generation operation of a fuel cell system according to an embodiment of the present invention .

Hereinafter, with reference to FIG. 4, air flow during power generation operation of the fuel cell system 1 will be described.

During power generation operation of the fuel cell system 1, an air flow toward the stack 20 may be formed according to the operation of the second blower 72. Specifically, the air flowing into the second external air inflow passage 203 is connected to the first switching valve 223 so that the first purge passage 221 and the suction end 203 of the second blower 72 are connected. It may flow into the second blower 72. The air introduced into the second blower 72 may be pressurized by the rotating impeller 73 and supplied to the humidifying device 23. The air supplied to the humidifier 23 receives moisture from air containing moisture generated by a chemical reaction in the stack 20, and then the stack side air humidification passage 205 and the stack inlet end 205 It may be supplied to the stack 20 through the second switching valve 224 that is switched to be connected. The air supplied to the stack 20 may produce electricity through a chemical reaction with the reformed gas supplied from the reformer 140 and then be discharged into the stack-side air discharge passage 211. The air discharged through the stack-side air discharge passage 211 passes through the open purge valve 225 and is supplied back to the humidifier 23. After supplying moisture to the air supplied to the stack 20, it is discharged to the outside. may be discharged.

<Fuzzy operation>

Figure 5 is a diagram for explaining a purge operation (stop operation) of a fuel cell system according to an embodiment of the present invention.

Hereinafter, with reference to FIG. 5, air flow during purge operation of the fuel cell system 1 will be described.

Referring to FIG. 5A, after the power generation operation of the fuel cell system 1 ends, an air flow toward the second blower 72 may be formed according to the operation of the second blower 72. Specifically, the air remaining in the stack 20 may be blocked from flowing to the humidifier 23 by the closed purge valve 225 and may flow into the first purge passage 221. The air flowing into the first purge passage 221 passes through the first switching valve 223, which is switched to connect the first purge passage 221 and the suction end 203 of the second blower, to the second blower 72. can be supplied. The air supplied to the second blower 72 may be pressurized by the rotating impeller 73 and supplied to the humidifying device 23. The air supplied to the humidifier 23 flows into the second purge passage 222 through the second switching valve 224, which is switched to connect the stack side air humidification passage 205 and the second purge passage 222. It can be. The air flowing into the second purge passage 222 may be blocked from flowing to the stack outlet end 211 by the closed purge valve 225, and may be supplied back to the humidifier 23 and discharged to the outside.

By the purge operation of the fuel cell system described above, external air flowing into the stack 20 is blocked, and the air remaining in the stack 20 is discharged to the outside, thereby preventing oxidation of the cathode electrode part of the stack 20. It is possible to prevent a decrease in the lifespan of the stack 20 due to this.

Referring to FIGS. 5B and 5C, when it is determined that the remaining oxygen in the stack 20 has been removed based on the pressure value measured through the pressure gauge 57, the outside air is supplied to the second outside air inflow passage 203 and It may be supplied to the second blower 72 through the first switching valve 223, which is switched to connect the suction end 203 of the second blower 72. The air supplied to the second blower 72 may be pressurized by the rotating impeller 73 and supplied to the humidifying device 23. The air supplied to the humidifier 23 flows into the second purge passage 222 through the second switching valve 224, which is switched to connect the stack side air humidification passage 205 and the second purge passage 222. It can be. The air flowing into the second purge passage 222 may be blocked from flowing to the stack outlet end 211 by the closed purge valve 225, and may be supplied back to the humidifier 23 and discharged to the outside.

Thereafter, when a predetermined time has elapsed, the operation of the second blower 72 is stopped, and the fuel cell system 1 can maintain a standby state for power generation operation.

Figure 6 is a control block diagram of a fuel cell system according to an embodiment of the present invention.

Referring to FIG. 6, the fuel cell system 1 may further include at least one control unit (M). The control unit M may include at least one processor. Here, the processor may be a general processor such as a central processing unit (CPU). Of course, the processor may be a dedicated device such as an ASIC or another hardware-based processor.

The control unit M can control the overall operation of the fuel cell system 1. The control unit may be connected to each component provided in the fuel cell system 1 and may transmit and/or receive signals to and from each component. For example, the control unit may process signals received from each component provided in the fuel cell system 1, and send a control signal according to the result of signal processing to each component provided in the fuel cell system 1. Can be sent.

For example, the control unit M may vary the air flow path by adjusting the switching of the first switching valve 223 and the second switching valve 224 according to the operation mode. Additionally, the control unit M may block air flow by controlling the opening and closing of the purge valve 225 according to the operation mode.

7 and 8 are flowcharts of a control method of a fuel cell system according to an embodiment of the present invention.

Referring to FIG. 7, the control unit M may set the power generation amount input from the user through the input unit (not shown) as the target power generation amount (S11).

After S11, the control unit (M) may switch the air flow path by adjusting the first switching valve 223 so that the second external air inlet flow path 203 and the blower suction end 203 are connected (S12). Accordingly, outside air can be supplied to the second blower 72 along the second outside air inflow passage 203.

After S12, the control unit (M) may switch the air flow path by adjusting the second switching valve 224 so that the stack side air humidifying flow path 205 and the stack inlet end 205 are connected (S13). Accordingly, the air humidified in the humidifier 23 can be supplied to the stack 20 along the stack-side air humidification passage 205.

After S13, the control unit (M) may open the purge valve 225 so that the stack-side air discharge passage 211 is opened (S14). Accordingly, air containing moisture after a chemical reaction in the stack 20 is supplied to the humidifier 23 along the air discharge passage 211, thereby supplying moisture to the air supplied to the stack 20.

After S14, the control unit M may perform a power generation operation by adjusting the rotation speed of the second blower 72 to satisfy the flow rate according to the user target power generation amount (S15).

After S15, the control unit (M) can determine whether the power generation operation is finished (S16). For example, the control unit M may end the power generation operation when receiving a power generation operation termination signal from the user through an input unit (not shown). Additionally, the control unit (M) can end the power generation operation when an error occurs in the system. An example of an error occurring in the system may be a case where a sufficient air flow rate is not supplied from the second blower 72 to the stack 20 compared to the power generation amount. Specifically, the control unit M may end the power generation operation when the flow rate measured by the air flow meter 53 is less than the set value. Here, the set value may mean a flow rate value according to the user's target power generation amount.

When the power generation operation is terminated (Yes in S16), the control unit (M) can enter the purge operation (S17). On the other hand, if the power generation operation has not ended (No in S16), the control unit (M) can return to S15 and perform the power generation operation.

Referring to FIG. 8, after S17, the control unit M may perform a purge operation. Specifically, the control unit (M) may switch the air flow path by adjusting the first switching valve 223 so that the first purge flow path 221 and the second blower suction end 203 are connected (S21). Accordingly, the flow of external air supplied to the stack 20 is blocked, and the air remaining in the stack 20 can be supplied to the second blower 72 along the first purge passage 221.

After S21, the control unit (M) may switch the air flow path by adjusting the second switching valve 224 so that the stack side air humidifying flow path 205 and the second purge flow path 222 are connected (S22). Accordingly, the air discharged from the humidifier 23 may be supplied back to the humidifier 23 along the second purge passage 222 and discharged to the outside.

After S22, the control unit M may close the purge valve 225 (S23). Accordingly, the air discharged from the humidifier 23 is supplied back to the humidifier 23 along the second purge passage 222, and the air discharged from the stack 20 is supplied to the first purge 221. 2 Can be supplied to the blower (72).

After S23, the control unit M may perform a purge operation for a predetermined time to remove air remaining in the stack (S24).

After S24, the control unit M may determine whether the purge operation is complete by comparing the pressure of the first purge passage 221 measured by the pressure gauge 57 with the set value (S25). For example, the control unit (M) determines that the purge operation is not completed when the pressure of the first purge passage 221 exceeds the set value, and when the pressure of the first purge passage 221 is less than the set value. , it can be determined that the purge operation has been completed. Here, the set value is a value at which it is determined that all remaining air in the stack has been removed, and may mean a value that is atmospheric pressure or negative pressure compared to atmospheric pressure.

If the purge operation is not completed (No in S25), the control unit M can return to S24 and continue performing the purge operation.

When the purge operation is completed (Yes in S25), the control unit (M) adjusts the first switching valve 223 so that the second external air inlet flow path 203 and the second blower inlet end 203 are connected to the air flow path. can be switched (S26).

After S26, the control unit M may stop the operation of the second blower 72 after a predetermined time has elapsed (S27). Accordingly, the purge operation is completely terminated, and the fuel cell system 1 can maintain a standby state for performing the power generation operation.

The attached drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical idea disclosed in the present specification is not limited by the attached drawings, and all changes and equivalents included in the spirit and technical scope of the present invention are not limited to the attached drawings. It should be understood to include water or substitutes.

Likewise, although operations are depicted in the drawings in a particular order, this should not be construed to mean that those operations must be performed in the specific order or sequential order shown or that all of the depicted operations must be performed to obtain desirable results. You can. In certain cases, multitasking and parallel processing may be advantageous.

In addition, although preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific embodiments described above, and the technical field to which the invention pertains without departing from the gist of the present invention as claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be understood individually from the technical idea or perspective of the present invention.

10: fuel processing device 20: stack
53: air flow meter 57: pressure gauge
72: Second blower 203: Second external air inflow path
204: Stack side air supply passage 205: Stack side air humidification passage
211: Stack side air discharge passage 221: First purge passage
222: Second purge flow path 223: First switching valve
224: second switching valve 225: purge valve

Claims (14)

Stacks that generate electricity;
A blower that supplies air to the stack;
a humidifier disposed between the stack and the blower, supplying moisture to the air discharged from the blower and discharging the air discharged from the stack to the outside;
a first switching valve disposed at the front of the blower and supplying external air or air discharged from the stack to the blower;
a first purge passage connecting the stack discharge end and the first switching valve and guiding air discharged from the stack to the first switching valve;
a second switching valve disposed at a rear end of the humidifying device and supplying air discharged from the humidifying device to the stack or re-supplying the air discharged from the humidifying device to the humidifying device;
a second purge passage connecting the second switching valve and the stack discharge end and guiding the air discharged from the humidifying device to the humidifying device; and
A purge valve disposed at the discharge end of the stack and guiding air discharged from the stack to the first purge passage.
According to paragraph 1,
It includes a control unit that controls switching of the first and second switching valves, opening and closing of the purge valve, and operation of the blower according to the operation mode,
The control unit,
During purge operation, the first switching valve is adjusted so that the first purge flow path and the blower are connected, the second switching valve is adjusted so that the humidifier and the second purge flow path are connected, and the water discharged from the stack is adjusted. A fuel cell system in which the purge valve is closed to allow air to flow into the first purge passage, and the blower is operated to remove air remaining in the stack.
According to paragraph 2,
A pressure gauge disposed in the first purge passage and measuring the pressure of the first purge passage,
The control unit,
A fuel cell system that adjusts the first switching valve so that external air is supplied to the blower when the pressure of the first purge passage detected by the pressure gauge is below a set value.
According to paragraph 3,
The set value is a fuel cell system that is atmospheric pressure or a pressure more negative than atmospheric pressure.
According to paragraph 1,
The purge valve is,
A fuel cell system located between a branch point of the first purge flow path and a branch point of the second purge flow path.
According to clause 5,
A fuel cell system in which a branch point of the first purge flow path is located closer to the stack than a branch point of the second purge flow path.
According to paragraph 1,
It includes a control unit that controls the first switching valve and the second switching valve according to the operation mode, and controls opening and closing of the purge valve and operation of the blower,
The control unit,
During power generation operation, the first switching valve is adjusted so that external air is supplied to the blower, the second switching valve is switched so that the humidifier and the stack are connected, and the blower is operated to supply external air to the stack. Fuel cell system supplied.
In clause 7,
It is disposed at the rear end of the blower and includes an air flow meter that measures the air flow rate supplied to the stack,
The control unit,
When the air flow rate measured by the air flow meter is less than the set value, the first switching valve is adjusted so that the first purge flow path and the blower are connected, and the second switching valve is adjusted so that the humidifier and the second purge flow path are connected. A fuel cell system that enters a purge operation by adjusting a switching valve and closing the purge valve so that air discharged from the stack flows into the first purge passage.
Stacks that generate electricity; A blower that supplies air to the stack; a humidifier that supplies moisture to the air discharged from the blower and discharges the air discharged from the stack to the outside; a purge valve that guides air discharged from the stack to the blower; a first switching valve that supplies external air or air discharged from the stack to the blower; and a second switching valve that supplies air discharged from the humidifier to the stack or re-supplies the air discharged from the humidifier to the humidifier,
performing a power generation operation to generate electricity in the stack by supplying air to the stack through the blower; and
A control method of a fuel cell system comprising performing a purge operation to remove air remaining in the stack by adjusting the first switching valve, the second switching valve, and the purge valve at the end of the power generation operation.
According to clause 9,
The step of performing the power generation operation is,
Fuel that switches the first switching valve to connect the air inlet flow path and the blower, switches the second switching valve to connect the humidifier and the stack, and operates the blower to supply external air to the stack. Control method of battery system.
According to clause 9,
It is disposed at the rear end of the blower and includes an air flow meter that measures the air flow rate supplied to the stack,
A control method for a fuel cell system that terminates the power generation operation and performs a purge operation when a power generation operation termination signal is received from an input unit or the air flow rate measured by the air flow meter is less than the set value.
According to clause 9,
The step of performing the purge operation is,
The first switching valve is adjusted so that the first purge passage and the blower are connected, the second switching valve is adjusted so that the humidifier and the second purge passage are connected, and the air discharged from the stack is connected to the first purge. A control method of a fuel cell system that closes the purge valve to allow flow to flow.
According to clause 12,
A control method for a fuel cell system that supplies external air to the blower by adjusting the first switching valve so that the air inlet flow path and the blower are connected when the pressure of the first purge passage detected by the pressure gauge is below the set value.
According to clause 13,
The set value is atmospheric pressure or a negative pressure than atmospheric pressure.