Triple cogeneration fuel cell system using pure hydrogen and its operation control method.

Abstract

The present disclosure provides a fuel cell system for triple combined heat and power that is environmentally friendly by using pure oxygen as fuel and has improved economic efficiency through a recirculation system. The fuel cell system for triple combined heat and power can maximize energy conversion efficiency through a heat pump-linked fuel cell system and a recirculation system.

Description

Technology Field

[0001] The present invention relates to a fuel cell system using pure oxygen, and specifically to a fuel cell system for triple combined heat and power. Background Technology

[0002] A triple combined heat and power (CHP) system is a complex energy system installed in factories, buildings, vehicles, etc., that simultaneously produces electrical, heating, and cooling energy from a single energy source. Depending on the operating method, such triple CHP systems can be classified into engine-based and fuel cell-based operating systems.

[0003] Among these, fuel cell-based triple combined heat and power systems have outstanding advantages in terms of environmental friendliness and efficiency, as they can overcome the problems of air pollution and the depletion of fossil fuels. Fuel cells are power generation devices that directly convert chemical energy generated by the oxidation of fuel into electrical energy, and due to their high efficiency, pollution-free operation, noise-free operation, and the ability to use various fuels, technological development is actively underway in many countries around the world, including the United States, Japan, and Germany.

[0004] Fuel cells vary depending on the type of electrolyte, operating temperature, and application. Depending on the temperature, high-temperature types at 600°C or higher include solid oxide fuel cells (SOFC) and molten carbonate fuel cells (MCFC), while low-temperature types at 200°C or lower include alkaline fuel cells (AFC), phosphoric acid fuel cells (PAFC), and polymer electrolyte fuel cells (PEFC or proton exchange membrane fuel cells, PEMFC).

[0005] In addition, fuel cell systems supply more hydrogen and air to the fuel cell stack than is required for the cell reaction in order to ensure performance and extend the lifespan of the fuel cell stack. Consequently, 20 to 40 percent of the hydrogen supplied to the fuel cell stack does not react and is discharged from the fuel cell stack as unreacted hydrogen, resulting in unnecessary losses. To address this problem and improve the economic efficiency of the fuel cell system, the need for measures such as methods for treating unreacted hydrogen is being discussed. The problem to be solved

[0006] The present disclosure aims to provide a fuel cell system for triple combined heat and power that is environmentally friendly by using pure hydrogen as fuel and has improved economic efficiency through a recirculation system.

[0007] The present disclosure aims to provide a fuel cell system for triple combined heat and power that maximizes energy conversion efficiency through a heat pump-linked fuel cell system and a recirculation system. means of solving the problem

[0008] The present disclosure provides a triple combined heat and power generation system comprising: a fuel cell stack including a fuel supply system and an air supply system; and a fuel cell-linked absorption cooler, wherein the system includes a pure hydrogen recirculation system that feeds pure hydrogen as fuel into the fuel supply system to react with oxygen, and recovers unreacted pure hydrogen discharged from the fuel cell stack and feeds it back into the fuel supply system.

[0009] The above-described pure water recirculation system may include a recirculation blower and control the flow rate and pressure of the recirculated pure water through the recirculation blower.

[0010] The fuel cell system for triple combined heat and power of the present disclosure may be such that the flow rate of the recirculated pure carbon does not exceed the flow rate of the unreacted pure carbon.

[0011] The fuel cell system for triple combined heat and power of the present disclosure may be such that the pressure of the recirculated pure water is higher than the discharge pressure of the flow controller of the fuel supply system.

[0012] The flow rate of the above-mentioned recirculated pure water may be 10 to 30 LPM.

[0013] The above fuel cell stack may be a high-temperature polymer electrolyte membrane fuel cell stack operated in a temperature range of 120 to 180°C.

[0014] The above-described fuel cell system for triple combined heat and power includes an emergency stop system, and the emergency stop system may activate an emergency stop mode when any one of the following conditions is satisfied: a hydrogen flow rate in the fuel supply system of less than 10 LPM, an oxygen flow rate in the air supply system of less than 10 LPM, an average voltage of the fuel cell stack of less than 0.4 V, a refrigerant temperature at the fuel cell stack outlet of 170°C or higher, a refrigerant temperature at the fuel cell stack outlet of 120°C or lower, or an AC voltage produced by the fuel cell inverter of less than 200 V.

[0015] The above emergency stop system may include: a step of activating an emergency stop mode; a step of stopping the supply of pure oxygen and oxygen from the fuel supply system and the air supply system; and a step of cooling the stack temperature until the temperature of the fuel cell stack becomes less than 80°C.

[0016] The absorption cooler may be characterized by comprising: a first generator for separating a refrigerant into gaseous and liquid phases; a second generator for separating a refrigerant introduced from the first generator into gaseous and liquid phases; a condenser for converting the refrigerant supplied from the first generator and the second generator, respectively, into a liquid phase; an evaporator for producing chilled water by cooling hot water through the evaporation of the refrigerant introduced from the condenser; an absorber for reabsorbing the vapor of the refrigerant introduced from the evaporator; and a cooling tower for providing cooling water to cool the absorber and the condenser.

[0017] The above absorption cooler may form the absorber and the evaporator into a single chamber. Effects of the invention

[0018] A fuel cell system for triple combined heat and power according to one embodiment of the present disclosure can achieve excellent environmental friendliness by reducing carbon emissions through a pure carbon recirculation system and excellent economic efficiency.

[0019] A fuel cell system for triple combined heat and power according to one embodiment of the present disclosure can maximize energy efficiency by enabling emergency control according to specific conditions. Brief explanation of the drawing

[0020] FIG. 1 is a schematic diagram showing the configuration of a fuel cell system for triple combined heat and power according to one embodiment of the present disclosure. Figure 2 shows the specific configuration of an absorption cooler in the triple combined heat and power fuel cell system of Figure 1. Figure 3 shows the discharge hydrogen flow rate at the flow controller downstream of the high-pressure hydrogen tank according to the current in a pure hydrogen recirculation system. Figure 4 shows the recirculation blower characteristic curve in a pure oxygen recirculation system. Specific details for implementing the invention

[0021] The present invention will be described in detail below. Unless otherwise defined, terms used in this specification should be interpreted as generally understood by those skilled in the art. The drawings and embodiments of this specification are intended to enable those skilled in the art to easily understand and practice the present invention; therefore, details that may obscure the essence of the invention may be omitted from the drawings and embodiments, and the present invention is not limited to the drawings and embodiments.

[0022] The singular form used in this specification may be intended to include the plural form unless specifically indicated otherwise in the context.

[0023] Furthermore, the numerical range used in this invention includes lower and upper limits and all values ​​within the range, increments logically derived from the form and width of the defined range, all of the specified values, and all possible combinations of upper and lower limits of the numerical range defined in different forms. Unless otherwise specifically defined in the specification of this invention, values ​​outside the numerical range that may occur due to experimental error or rounding are also included in the defined numerical range.

[0024] In this specification, terms such as "include," "have," and "have" mean that the features or components described in the specification are present, and unless specifically limited, this does not preclude the possibility that one or more other features or components may be added.

[0025] The fuel cell system for triple combined heat and power of the present disclosure may be a triple combined heat and power generation system comprising a fuel cell stack including a fuel supply system and an air supply system; and a fuel cell-linked absorption cooler, wherein the system may include a pure hydrogen recirculation system that feeds pure hydrogen as fuel into the fuel supply system to react with oxygen, and recovers unreacted pure hydrogen discharged from the fuel cell stack and feeds it back into the fuel supply system.

[0026] A fuel cell system for triple combined heat and power according to one embodiment of the present disclosure can further maximize the efficiency of the system's electrical conversion by using pure hydrogen instead of reformed hydrogen in a system using a high temperature polymer electrolyte fuel cell (HT-PEFC) that operates at a high temperature of 100°C or higher.

[0027] According to one embodiment of the fuel cell system for triple combined heat and power of the present disclosure, the pure hydrogen recirculation system may include a recirculation blower and control the flow rate and pressure of the recirculated pure hydrogen through the recirculation blower. The pure hydrogen recirculation system of the present disclosure may recirculate unreacted hydrogen to eliminate hydrogen that is wasted to the outside even during startup before the triple combined heat and power system reaches a steady state.

[0028] Specifically, the flow rate of the recirculated pure water may not exceed the flow rate of the unreacted pure water.

[0029] Specifically, the pressure of the recirculated pure water may be higher than the discharge pressure of the flow controller of the fuel supply system.

[0030] According to one embodiment, the voltage of the pure oxygen recirculation blower may be 1.0 to 2.5 V, specifically 1.0 to 2.0 V. In addition, the recirculation flow rate of the pure oxygen recirculation blower may be 10 to 30 LPM, specifically 10 to 25 LPM, more specifically 10 to 20 LPM.

[0031] According to one embodiment, the fuel cell stack may be a high-temperature polymer electrolyte membrane fuel cell stack operated in a temperature range of 120 to 180°C, and specifically, may be operated in a temperature range of 140 to 160°C.

[0032] A fuel cell system for triple combined heat and power according to one embodiment of the present disclosure may include an emergency stop system capable of stopping the operation of the fuel cell system when conditions are met by monitoring a specific environment.

[0033] Specifically, the emergency stop system may activate an emergency stop mode when any one of the following conditions is satisfied: when the hydrogen flow rate in the fuel supply system is less than 10 LPM, when the oxygen flow rate in the air supply system is less than 10 LPM, when the average voltage of the fuel cell stack is less than 0.4 V, when the refrigerant temperature at the fuel cell stack outlet is 170°C or higher, when the refrigerant temperature at the fuel cell stack outlet is 120°C or lower, or when the AC voltage produced by the fuel cell inverter is less than 200 V.

[0034] Specifically, the emergency stop system may include the step of activating an emergency stop mode; the step of stopping the supply of pure oxygen and oxygen from the fuel supply system and the air supply system; and the step of cooling the stack temperature until the temperature of the fuel cell stack becomes less than 80°C.

[0035] A fuel cell system for triple combined heat and power according to one embodiment of the present disclosure includes an absorption cooler, which can maximize energy production efficiency as well as environmental friendliness and economic efficiency.

[0036] Specifically, according to one embodiment, the absorption cooler may be characterized by comprising: a first generator for separating a refrigerant into a gaseous and a liquid phase; a second generator for separating a refrigerant introduced from the first generator into a gaseous and a liquid phase; a condenser for converting the refrigerant supplied from the first generator and the second generator, respectively, into a liquid phase; an evaporator for producing chilled water by cooling hot water through the evaporation of the refrigerant introduced from the condenser; an absorber for reabsorbing the vapor of the refrigerant introduced from the evaporator; and a cooling tower for providing cooling water to cool the absorber and the condenser.

[0037] Specifically, the absorption cooler may form the absorber and the evaporator into a single chamber.

[0038] Hereinafter, the fuel display system for triple combined heat and power is described in detail based on the following drawings.

[0039] FIG. 1 is a schematic diagram of a fuel cell system for triple heat and power according to the present disclosure. Referring to FIG. 1, the fuel cell system for triple heat and power may include a fuel cell stack (100), a fuel cell-linked absorption cooler (200), and a pure oxygen recirculation system (300). That is, unreacted pure oxygen can be recirculated and utilized from a high-temperature polymer electrolyte fuel cell (HT-PEFC), and a cooling system based on the absorption cooler (200) can be provided using waste heat released from the fuel cell stack.

[0040] Specifically, the pure water recirculation system may include a pure water recirculation blower, and the flow rate and pressure of the recirculated pure water can be controlled by controlling the rpm of the recirculation blower.

[0041] More specifically, a fuel cell system for triple heat and power according to the present disclosure will be described with reference to FIG. 2. FIG. 2 is a configuration diagram of a fuel cell system for triple heat and power according to the present disclosure. Referring to FIG. 2, the fuel cell system for triple heat and power according to the present disclosure comprises a fuel cell stack (100) and a first generator (1 st Generator, 210), second generator (2 nd It may include an absorption cooler comprising a generator (220), a high temperature heat exchanger (230), a low temperature heat exchanger (240), a condenser (250), an evaporator (260), an absorber (270), and a cooling tower (280).

[0042] The fuel cell stack (100) includes a fuel supply system (110), an air supply system (120), and a heat recovery system (130). In this embodiment, the fuel cell stack (100) is preferably applied to a triple combined heat and power generation system in which the fuel cell operating temperature is in the range of 120 to 180°C. The heat recovery system (130) has a refrigerant inside that performs the function of cooling the fuel cell stack, and can also include a refrigerant vapor generator to simultaneously perform the function of a steam generator that evaporates the refrigerant.

[0043] An electrolyte membrane, although not shown, is included between the fuel supply system (110) and the air supply system (120), and electricity is generated through the reaction in the fuel supply system (110) and the air supply system (120), and the generated electricity is transmitted to the outside through an inverter.

[0044] The fuel supply system (110) may include a flow controller capable of controlling the flow rate and pressure of pure hydrogen supplied to the fuel cell stack (100). At this time, the pure hydrogen supplied to the fuel cell stack (100) can be controlled by increasing the amount of hydrogen discharged from the flow controller, and the amount of hydrogen discharged can be controlled according to the increase in current for increasing the electrical output of the fuel cell stack (100).

[0045] The fuel cell stack (100) is generally configured in a form in which a number of hydrogen electrodes, air electrodes, and cooling plates are repeatedly stacked, and this is simplified in FIG. 2. A typical high-temperature polymer electrolyte fuel cell is configured to include an independent refrigerant flow path passing through the cooling plate. Conventional technologies that combine a heat pump and a fuel cell to form a triple combined heat and power generation system also configured the refrigerant flow path of the fuel cell and the refrigerant flow path of the heat pump separately. However, in the present invention, the integrated refrigerant vapor generator included in the heat recovery system (130) integrates the flow paths that were previously configured separately, thereby reducing not only the fluid flow paths but also the number of devices such as condensers and pumps used in the fuel cell, which can reduce the size of the entire system and enable more efficient heat utilization.

[0046] The absorption heat pump in the present invention is a concept that includes an absorption cooler, and therefore, the absorption heat pump of the present invention may be interpreted as an absorption cooler.

[0047] The refrigerant used to cool the fuel cell as a fluid for the heat pump evaporates in the heat recovery system (130) due to the heat of the fuel cell stack (100). Depending on the load of the fuel cell, when the temperature is high, most of the refrigerant evaporates, and when the temperature is low, most of the refrigerant passes through in a liquid state and flows into the gas-liquid separator.

[0048] Specifically, the first generator (210) may be composed of a refrigerant vapor generator of the heat recovery system (130) and a small gas-liquid separator that separates the circulating refrigerant supplied therefrom into gaseous and liquid phases. The first generator (210) generates refrigerant vapor. If necessary, additional heat may be supplied to further increase the amount of gaseous refrigerant.

[0049] The gaseous refrigerant discharged from the first generator (210) can be directly supplied to the liquid portion of the second generator (220) through the pipe (5). Alternatively, the gaseous refrigerant discharged from the first generator (110) can be supplied to the condenser (250) through the pipe (5, 13) which includes a pipe structure that only transfers heat to the liquid portion.

[0050] The refrigerant supplied to the condenser (250) through the pipes (5, 9) loses heat while passing through the second generator (220), so some of it may be in a liquid state. Additionally, the refrigerant supplied to the condenser (250) may come into contact with a heat exchanger through which high-temperature cooling water flows in the form of a spray from the condenser (250).

[0051] The liquid refrigerant separated from the first generator (210) flows into the second generator (220) through the pipe (6). A high-temperature heat exchanger (230) may be placed in a part of the pipe (6, 7, 8). The heat recovered through the high-temperature heat exchanger (230) may be used to raise the temperature of the refrigerant supplied to the integrated refrigerant vapor generator included in the fuel cell stack (200), or may be used for building heating.

[0052] Meanwhile, in the second generator (220), a portion of the aqueous solution, which is a liquid circulating refrigerant, can be evaporated through the gaseous refrigerant supplied from the first generator (210) through the pipe (5), and the evaporated refrigerant flows into the condenser (250) through the pipe (13).

[0053] The liquid refrigerant of the second generator (220) is supplied to the absorber (270) through the pipes (10, 11, 12). A low-temperature heat exchanger (240) may be placed in a part of the pipes (10, 11, 12). The low-temperature heat exchanger (240), like the high-temperature heat exchanger (230), can raise the temperature of the aqueous solution supplied to the integrated refrigerant vapor generator included in the fuel cell stack (200).

[0054] Meanwhile, the absorber (270) receives low-temperature cooling water from the cooling tower (280) through the pipe (23), and can increase the temperature of the low-temperature cooling water through the heat exchanger of the absorber (270) to discharge high-temperature cooling water through the pipe (24). The discharged high-temperature cooling water is supplied to the condenser (250) through the pipe (24, 19). The temperature of the high-temperature cooling water supplied to the condenser (250) is further increased through the heat exchanger inside the condenser (250), and is supplied back to the cooling tower (180) through the pipe (20).

[0055] The condenser (250) includes a high-temperature cooling water pipe separate from the circulating fluid pipe, and the circulating fluid in the gaseous state comes into contact with the high-temperature cooling water pipe and is converted into a liquid state by condensation.

[0056] The liquid refrigerant discharged from the condenser (250) flows into the evaporator (260) through the pipes (14, 15). In the evaporator (260), the refrigerant supplied through the pipes (14, 15) is brought into contact with the surface of the hot water pipes through an internal heat exchanger using a method such as injection, and the refrigerant in contact with the hot water pipes evaporates and flows into the absorber (270) through the pipe (16). Hot water heated by the hot air inside the building is supplied to the evaporator (260) through the pipe (22), and its temperature is lowered by the refrigerant in the evaporator (260). The chilled water, with its temperature lowered, flows back into the building through the pipe (21) and can be used for cooling the building, etc. The evaporator (260) and the absorber (270) can be configured as an integrated chamber without separate piping, and the gaseous refrigerant discharged from the evaporator (260) is directly introduced into the absorber (270) through the piping (16) or the integrated chamber. When cooling is not required in the building, the refrigerant is supplied directly from the evaporator (260) to the absorber (270) without any reaction. In the absorber (270), the heat generated as the cooling fluid in the form of an aqueous solution absorbs the vapor of the refrigerant is discharged through an internal heat exchanger using the high-temperature cooling water piping (24), thereby lowering the temperature of the refrigerant and converting the fuel cell stack (200) into a state where it can be cooled. Additionally, the heat recovered from the absorber (270) can be used for heating.

[0057] In the absorber (270), heat generated while absorbing vapor of the refrigerant in the form of an aqueous solution is discharged through an internal heat exchanger using a high-temperature cooling water pipe (24), thereby lowering the temperature of the circulating fluid solution and converting the fuel cell stack (100) into a state where it can be cooled. Additionally, the heat recovered from the absorber (270) can be used for heating.

[0058] According to one embodiment, the fuel cell system for triple combined heat and power may further include a pre-cooling heat exchanger. The pre-cooling heat exchanger may perform heat exchange to provide cold water from low-temperature cooling water produced in the cooling tower of an absorption cooler. The cooling tower may be connected to the absorption cooler and may provide cooling water cooled in contact with the atmosphere depending on the temperature of the outside air. For example, when the temperature of the outside air is low, cooling water cooled in contact with the atmosphere may be provided directly to the pre-cooling heat exchanger.

[0059] Hereinafter, the fuel cell system for triple combined heat and power according to the present invention will be described in more detail through specific embodiments. However, the following embodiments are merely references for the detailed explanation of the present invention and the present invention is not limited thereto and may be implemented in various forms. Furthermore, the terms used in the description of the present invention are intended merely to effectively describe specific embodiments and are not intended to limit the present invention.

[0061] [Example 1] Fuel cell system for triple combined heat and power

[0062] As shown in FIGS. 1 and 2, a triple combined heat and power fuel cell system was configured including a fuel cell (100), a cold water production system (200) including a fuel cell-linked absorption cooler, and a pure hydrogen recirculation system (300), and operated with a control logic to eliminate wasted hydrogen even during startup before the system reached a normal state as follows.

[0063] 1) Fuel cell stack preheating step

[0064] The temperature of the fuel cell stack (100) was controlled by circulating a refrigerant at 145°C through the heat recovery system (130) of the fuel cell stack so that it reached 120°C, which is the minimum operating temperature of the HT-MEA, a membrane electrode assembly used in the HT-PEM.

[0065] 2) Oxygen and hydrogen supply process to the fuel cell stack

[0066] The oxygen supply was controlled by increasing the amount of air discharged from the air blower in accordance with the increase in current for increasing the electrical output of the fuel cell stack (100).

[0067] As shown in FIG. 3, the hydrogen supply was controlled by increasing the amount of hydrogen discharged from the flow controller at the rear of the high-pressure hydrogen tank in accordance with the increase in current for increasing the electrical output of the fuel cell stack (100).

[0068] 3) Hydrogen Recirculation Process

[0069] The flow rate and pressure of the hydrogen recirculation blower in the hydrogen recirculation system (300) were controlled so that unreacted hydrogen in the fuel cell stack (100) is not discarded outside but supplied back to the inlet of the stack according to the oxygen and hydrogen supply.

[0070] Specifically, as shown in FIG. 4, the correlation between the pressure difference between the inlet and outlet of the hydrogen recirculation blower and the flow rate of the recirculated hydrogen was investigated, and the flow rate and pressure of the recirculated hydrogen were controlled by adjusting the rpm of the hydrogen recirculation blower so that the flow rate of the recirculated hydrogen does not exceed the amount of unreacted hydrogen and the pressure of the recirculated hydrogen is maintained slightly higher than the discharge pressure of the flow rate controller at the downstream end of the high-pressure hydrogen tank of the fuel supply system (110).

[0071] Accordingly, the H2 flow rate of the recirculation blower based on 160 cells and 0.2A / cm2 (64A) was set to 15.9 LPM, and the recirculation blower input was set to 1.5V.

[0073] [Example 2] Emergency control system

[0074] The fuel cell system for triple heat and power of the present disclosure implements an emergency stop control system when any one of the following emergency stop occurrence situations is satisfied.

[0075] 1) Situation where an emergency stop occurs

[0076] - When the hydrogen flow rate in the fuel supply system (110) is less than 10 LPM

[0077] - When the oxygen flow rate in the air supply system (120) is less than 10 LPM

[0078] - When the average voltage of the fuel cell stack (100) is less than 0.4V

[0079] - When the refrigerant temperature at the outlet of the fuel cell stack (100) is 170℃ or higher

[0080] - When the refrigerant temperature at the outlet of the fuel cell stack (100) is 120℃ or lower

[0081] - When the AC voltage produced by the fuel cell inverter is less than 200V

[0082] 2) Emergency Stop Control System

[0083] In a situation satisfying any one of the above emergency stop occurrence situations, the following emergency stop control system is implemented.

[0084] 1. Power OFF for the triple combined heat and power fuel cell system

[0085] 2. The supply of pure oxygen and oxygen from the fuel supply system (110) and the air supply system (120) is stopped, and the recirculation pump of the hydrogen recirculation system (300) is turned OFF.

[0086] 3. The hydrogen valve in the fuel supply system (110) is closed, and nitrogen purging is prepared.

[0087] 4. Switch to operating mode in the fuel cell stack (100).

[0088] 5. Cooling the stack temperature until the temperature of the fuel cell stack (100) becomes less than 80℃

[0089] 6. Turn off the oil pump and coolant pump when the stack temperature is below 80℃.

[0090] 7. Turn off temperature and water level control of the thermal storage tank

[0092] As described above, the present invention has been explained by specific details, limited embodiments, and comparative examples; however, these are provided merely to aid in a more comprehensive understanding of the invention, and the invention is not limited to the above embodiments. Those skilled in the art can make various modifications and variations from this description.

[0093] Accordingly, the scope of the present invention is not limited to the described embodiments, and all things equivalent to or having equivalent variations to the claims set forth below, as well as the claims set forth below, shall be considered to fall within the scope of the concept of the present invention. Explanation of the symbols

[0095] 100 : Fuel cell stack 110: Fuel supply system 120: Air supply system 130: Heat recovery system 200 : Cold water production system (absorption chiller) 210 : 1st generator 220 : 2nd generator 230 : High-temperature heat exchanger 240 : Low-temperature heat exchanger 250 : Condenser 260 : Evaporator 270 : absorber 280 : Cooling tower 300: Pure Material Circulation System

Claims

Claim 1 A triple combined heat and power generation system comprising: a fuel cell stack including a fuel supply system and an air supply system; and a fuel cell-linked absorption cooler, wherein the fuel cell system includes a pure hydrogen recirculation system that feeds pure hydrogen as fuel into the fuel supply system to react with oxygen and recovers unreacted pure hydrogen discharged from the fuel cell stack and feeds it back into the fuel supply system, wherein the pure hydrogen recirculation system includes a recirculation blower and controls the flow rate and pressure of the recirculated pure hydrogen through the recirculation blower, such that the flow rate of the recirculated pure hydrogen does not exceed the flow rate of unreacted pure hydrogen, and such that the pressure of the recirculated pure hydrogen is higher than the discharge pressure of the flow rate controller of the fuel supply system. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 A fuel cell system for triple combined heat and power according to claim 1, wherein the flow rate of the recirculated pure water is 10 to 30 LPM. Claim 6 A fuel cell system for triple combined heat and power according to claim 1, wherein the fuel cell stack is a high-temperature polymer electrolyte membrane fuel cell stack operated in a temperature range of 120 to 180°C. Claim 7 A fuel cell system for triple combined heat and power according to claim 1, wherein the fuel cell system for triple combined heat and power includes an emergency stop system, and the emergency stop system activates an emergency stop mode when any one of the following conditions is satisfied: a hydrogen flow rate in the fuel supply system is less than 10 LPM, an oxygen flow rate in the air supply system is less than 10 LPM, an average voltage of the fuel cell stack is less than 0.4 V, a refrigerant temperature at the fuel cell stack outlet is 170°C or higher, a refrigerant temperature at the fuel cell stack outlet is 120°C or lower, and an AC voltage produced by the fuel cell inverter is less than 200V. Claim 8 A fuel cell system for triple combined heat and power according to claim 7, wherein the emergency stop system comprises: a step of activating an emergency stop mode; a step of stopping the supply of pure oxygen and oxygen from the fuel supply system and the air supply system; and a step of cooling the stack temperature until the temperature of the fuel cell stack becomes less than 80°C. Claim 9 A fuel cell system for triple combined heat and power according to claim 1, wherein the absorption cooler comprises: a first generator for separating a refrigerant into gaseous and liquid phases; a second generator for separating a refrigerant introduced from the first generator into gaseous and liquid phases; a condenser for converting the refrigerant supplied from the first generator and the second generator, respectively, into a liquid phase; an evaporator for producing chilled water by cooling hot water through the evaporation of the refrigerant introduced from the condenser; an absorber for reabsorbing the vapor of the refrigerant introduced from the evaporator; and a cooling tower for providing cooling water to cool the absorber and the condenser. Claim 10 In claim 9, the absorption cooler is a triple combined heat and power fuel cell system in which the absorber and the evaporator are formed into a single chamber.

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