Electricity-steam combined supply system for recovering complementary energy of proton exchange membrane fuel cell

Abstract

The invention relates to the field of low-grade waste heat utilization, in particular to a proton exchange membrane fuel cell waste energy recovery electricity-steam combined supply system, which comprises a fuel cell unit, a heat exchange membrane fuel cell unit and a heat exchange membrane fuel cell unit, the heat pump unit is connected with the fuel cell unit; the steam flash evaporation unit is connected with the heat pump unit; the water replenishing unit is connected with the fuel cell unit and the steam flash evaporation unit; the fuel cell unit provides a heat source for the heat pump unit; the steam flash evaporation unit absorbs heat of the heat pump to produce steam; the water replenishing unit recovers air waste heat, heats and replenishes water, water absorbing the waste heat is conveyed to the heat pump unit through the steam flash evaporation unit, unburnt hydrogen tail gas heat energy is recovered through a catalytic burner, pressure energy of air tail gas is recovered through an expansion machine, and air tail gas waste heat is recovered through an air-water heat exchanger. And all complementary energy of the proton exchange membrane fuel cell is recovered, so that the energy utilization rate of the whole system is improved.

Description

Technical Field

[0001] This invention relates to the field of low-grade waste heat utilization, and in particular to a combined power and steam system for recovering waste energy from a proton exchange membrane fuel cell. Background Technology

[0002] When hydrogen fuel cells are operating, chemical energy cannot be completely converted into electrical energy. Taking a typical proton exchange membrane fuel cell (PEMFC) as an example, its power generation efficiency is typically between 40% and 60%, meaning that 40% to 60% of the chemical energy is dissipated as heat. If this heat is directly wasted, it represents a huge energy loss. Fuel cell waste heat utilization technologies are mainly categorized based on the type of fuel cell (primarily considering operating temperature) and application scenario. High-temperature fuel cells such as solid oxide fuel cells (SOFC) have exhaust temperatures reaching hundreds or even thousands of degrees Celsius, resulting in high-grade waste heat that can be efficiently and diversely utilized, such as bottom-cycle power generation, steam reforming for hydrogen production, and combined heat and power (CHP) systems. Meanwhile, PEMFCs… The optimal operating temperature is approximately 60–80°C, requiring the use of low-temperature waste heat utilization technology. Low-temperature differential power generation is a promising method for utilizing low-temperature waste heat, but it is currently still in the laboratory research stage. The most direct and mature application is space heating and domestic hot water supply, i.e., combined heat and power (CHP) mode. This involves extracting the waste heat generated during PEMFC operation through a coolant loop and using a heat exchanger to heat domestic or heating water. Currently, the overall energy efficiency of this system can reach 80%–90%, with room for further improvement. Due to the low waste heat temperature of PEMFC, the waste heat utilization methods and application scenarios are limited, resulting in limited room for economic benefit improvement. Therefore, there is an urgent need to develop a more efficient and energy-saving low-grade heat utilization technology. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to provide a safe, reliable, and energy-efficient proton exchange membrane fuel cell combined power system for waste energy recovery.

[0004] The above-mentioned technical problems are solved by the following technical solution: This invention proposes a combined electric and steam power system for recovering waste energy from a proton exchange membrane fuel cell, comprising: a fuel cell unit; a heat pump unit connected to the fuel cell unit; a steam flash unit connected to the heat pump unit; and a water replenishment unit connected to the fuel cell unit and the steam flash unit; wherein, the fuel cell unit provides a heat source for the heat pump unit; the steam flash unit absorbs heat from the heat pump to produce steam; and the water replenishment unit recovers waste heat from the air, heats the water, and delivers the water that has absorbed waste heat to the heat pump unit through the steam flash unit.

[0005] In a preferred embodiment of the combined electric and gas power system for waste energy recovery from a proton exchange membrane fuel cell according to the present invention: the fuel cell unit includes a stack, the input end of the anode of the stack is connected to the output end of an ejector cycle integrated machine, the input end of the ejector cycle integrated machine is connected to the output end of a proportional valve, and the input end of the proportional valve is connected to a hydrogen storage tank.

[0006] In a preferred embodiment of the combined electric and gas power system for waste energy recovery from a proton exchange membrane fuel cell according to the present invention: the output end of the stack anode is connected to the input end of an exhaust valve, and the output end of the exhaust valve is connected to a catalytic combustor.

[0007] In a preferred embodiment of the combined electric and gas power system for waste energy recovery from a proton exchange membrane fuel cell according to the present invention: the input end of the fuel cell stack cathode is connected to the output end of the intercooler, the input end of the intercooler is connected to the output end of the air compressor; and the output end of the fuel cell stack cathode is connected to the catalytic combustor.

[0008] In a preferred embodiment of the combined power and steam power system for waste energy recovery of proton exchange membrane fuel cells according to the present invention: the heat pump unit includes an evaporator connected to the output end of the fuel cell stack cooling channel, the output end of the evaporator is connected to the input end of a circulation pump, and the output end of the circulation pump is connected to the cooling channel of the fuel cell stack.

[0009] In a preferred embodiment of the combined electric and gas power system for waste energy recovery from a proton exchange membrane fuel cell according to the present invention: the output end of the evaporator is connected to the input end of the superheater, the output end of the superheater is connected to the high-pressure inlet of the vapor injection enthalpy-enhancing compressor, the low-pressure outlet of the vapor injection enthalpy-enhancing compressor is connected to the input end of the condenser, the output end of the condenser has two branches, one branch is connected to the input end of the economizer, and the other branch is connected to the input end of the economizer through a throttle valve, the output end of the economizer is connected to the input end of the expansion valve, the output end of the expansion valve is connected to the input end of the evaporator, and the medium-pressure inlet of the vapor injection enthalpy-enhancing compressor is connected to the output end of the economizer.

[0010] In a preferred embodiment of the combined power and steam system for waste energy recovery from a proton exchange membrane fuel cell according to the present invention: the steam flash unit includes a pressure reducing valve connected to the output end of the condenser, the output end of the pressure reducing valve is connected to the input end of the pure water in the flash tank, the output end of the steam in the flash tank is connected to a steam delivery pipeline, the output end of the pure water in the flash tank is connected to the input end of a return water pump through a three-way valve, and the output end of the return water pump is connected to the input end of the condenser.

[0011] In a preferred embodiment of the combined power and steam power system for waste energy recovery from a proton exchange membrane fuel cell according to the present invention: the water replenishment unit includes a water storage tank connected to the output end of the air compressor cooling pipe, the input end of the air compressor cooling pipe is connected to the output end of the water inlet valve, the output end of the water inlet valve is also connected to the input end of the DC / DC transformer cooling pipe, the output end of the DC / DC transformer cooling pipe is connected to the input end of the water storage tank, the output end of the water storage tank is connected to the input end of the air-water heat exchanger, the output end of the air-water heat exchanger is connected to the input end of the water replenishment pump, and the output end of the water replenishment pump is connected to the output end of the flash tank through a three-way valve.

[0012] In a preferred embodiment of the combined power and steam power system for waste energy recovery from a proton exchange membrane fuel cell according to the present invention: the output end of the superheater is connected to the input end of the expander, and the exhaust port of the expander is connected to the input end of the air-water heat exchanger.

[0013] In a preferred embodiment of the combined power and steam power system for waste energy recovery from a proton exchange membrane fuel cell according to the present invention: the air compressor is coaxially connected to the expander.

[0014] The beneficial effects of this invention are as follows: By setting up a heat pump unit and a steam flash unit, and applying them to the recovery of waste heat from the coolant of a proton exchange membrane fuel cell (PEMFC) to generate high-temperature steam, the essential auxiliary components of the PEMFC system, such as the air compressor and intercooler, are modified for heat recovery. By setting up a catalytic burner to recover the heat energy of unburned hydrogen exhaust gas, by setting up an expander to recover the pressure energy of air exhaust gas, and by setting up an air-water heat exchanger to recover the waste heat of air exhaust gas, all the waste energy of the proton exchange membrane fuel cell is recovered. This not only improves the energy utilization rate, but also, because the heat pump evaporator is used as the PEMFC cooler, it helps the PEMFC system to operate stably and efficiently. This setup can produce high-temperature steam, which can expand the heating scenario from building heating to the industrial field, thereby improving the economic benefits of waste heat utilization in the PEMFC system. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention. Wherein: Figure 1 A flowchart of a combined electric power (CEHP) system for recovering residual energy from a proton exchange membrane fuel cell is shown. Figure 2 The graphs showing the changes in operating time and system energy utilization rate for different PEMFC systems are shown. Figure 3The diagram shows the average system energy utilization rate of different PEMFC systems over 20 years of operation. Detailed Implementation

[0016] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0017] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0018] Reference Figure 1 This embodiment provides a combined power and steam power system for recovering waste energy from a proton exchange membrane fuel cell, including a fuel cell unit 1; and... Heat pump unit 2 connected to fuel cell unit 1; and, A steam flash evaporation unit 3 connected to heat pump unit 2; and, Water replenishment unit 4 is connected to fuel cell unit 1 and steam flash unit 3; Among them, fuel cell unit 1 provides heat source for heat pump unit 2; steam flash unit 3 absorbs heat from heat pump to produce steam; water replenishment unit 4 recovers waste heat from air, heats water, and delivers the water that has absorbed waste heat to heat pump unit 2 through steam flash unit 3.

[0019] Specifically, such as Figure 1 As shown, the green area represents fuel cell unit 1, the gray area represents heat pump unit 2, the purple area represents steam flash unit 3, and the yellow area represents water replenishment unit 4.

[0020] In one embodiment provided in this application, the fuel cell unit 1 includes a stack 11, the input end of the anode of the stack 11 is connected to the output end of the ejector cycle integrated machine 12, the input end of the ejector cycle integrated machine 12 is connected to the output end of the proportional valve 13, the input end of the proportional valve 13 is connected to the hydrogen storage tank; the output end of the anode of the stack 11 is connected to the input end of the exhaust valve 14, and the output end of the exhaust valve 14 is connected to the catalytic burner 15.

[0021] The fuel cell stack 11 is the core component of the fuel cell unit 1. It is the component that generates electrical energy. The fuel cell stack consists of an anode, a cooling channel, and a cathode. The ejector cycle unit 12 is the component that introduces hydrogen, which is equivalent to a hydrogen delivery pump. The catalytic burner 15 is used to burn unburned hydrogen again. The burner 15 heats the air flowing out of the fuel cell stack to realize the conversion of the chemical energy of the exhaust gas into thermal energy for reuse. The proportional valve 13 is used to regulate the amount of hydrogen input. The exhaust valve 14 controls the exhaust gas discharge according to the set pressure.

[0022] Specifically, the external hydrogen storage tank is connected to the proportional valve 13 via a hydrogen pipeline. After passing through the proportional valve 13, the hydrogen enters the ejector circulation unit 12 and is then fed into the anode of the fuel cell stack 11. After the hydrogen is burned at the anode of the fuel cell stack 11, part of the exhaust gas is discharged through the exhaust valve 14, and the other part of the exhaust gas re-enters the ejector circulation unit 12. The exhaust gas flowing through the exhaust valve 14 enters the catalytic combustor 15 and is burned again.

[0023] In one embodiment provided in this application, the input terminal of the cathode of the fuel cell stack 11 is connected to the output terminal of the intercooler 16, and the input terminal of the intercooler 16 is connected to the output terminal of the air compressor 17; the output terminal of the cathode of the fuel cell stack 11 is connected to the catalytic burner 15, and the inlet of the air-side flow channel of the superheater 22 is connected to the outlet of the air-side flow channel of the catalytic burner 15 in the fuel cell unit 1; the air compressor 17 is coaxially connected to the expander 19, and can use the residual air pressure to increase kinetic energy, thereby reducing the load on the air compressor.

[0024] The air compressor 17 is the component that introduces air; the intercooler 16 cools down the high-temperature air coming out of the air compressor 17.

[0025] Specifically, after the air flows through the air compressor 17, it becomes high-temperature and high-pressure air, enters the intercooler 16, and then enters the cathode of the fuel cell stack 11; the exhaust air from the cathode of the fuel cell stack 11 enters the catalytic burner 15; the heated exhaust air enters the superheater 22 of the heat pump unit 2 to provide a heat source for the heat pump; the exhaust air from the heat pump superheater 22 still has a large pressure and enters the expander 19 to do work; the air from the expander 19 still has a high temperature and enters the air-water heat exchanger 44 of the water replenishment unit 4.

[0026] In one embodiment provided in this application, the inlet of the water-side flow channel of the evaporator 21 is connected to the outlet of the cooling flow channel of the fuel cell stack 11 in the fuel cell unit, the outlet of the water-side flow channel of the evaporator 21 is connected to the inlet of the circulation pump 18 in the fuel cell unit 1, and the output end of the circulation pump 18 is connected to the cooling flow channel of the fuel cell stack 11.

[0027] Among them, there is a circulating deionized water between the evaporator 21 and the cooling channel of the fuel cell unit 1. The waste heat of the fuel cell is discharged through the deionized water and supplied to the heat pump as a heat source.

[0028] The superheater 22 uses the air heated by the catalytic burner 15 as a heat source to heat all the gas-liquid mixture flowing out of the evaporator 21 into superheated steam and send it into the jet enthalpy compressor 23.

[0029] In one embodiment provided in this application, the outlet of the working fluid side channel of the evaporator 21 is connected to the inlet of the working fluid side channel of the superheater 22, the high-pressure inlet of the vapor injection enthalpy compressor 23 is connected to the outlet of the working fluid side channel of the superheater 22, the medium-pressure inlet of the vapor injection enthalpy compressor 23 is connected to the outlet of the gas phase side channel of the economizer 25, and the outlet (low-pressure port) of the vapor injection enthalpy compressor 25 is connected to the inlet of the working fluid side channel of the condenser 24.

[0030] It should be further explained that the jet enthalpy-enhancing compressor 23 is the core component, which mainly performs work on compressing the heat pump working fluid vapor to further increase the vapor temperature. This step is the key to improving the quality of low-grade waste heat. The high-temperature side of the condenser 24 contains the working fluid vapor, while the low-temperature side is supplied with circulating pure water from the steam flash evaporation unit 3. The high-temperature working fluid vapor heats the circulating water through the condenser 24.

[0031] In one embodiment provided in this application, there are two branches at the outlet of the working fluid side channel of the condenser 24. One branch is connected to the inlet of the liquid phase side channel of the economizer 25, and the other branch is connected to the inlet of the gas phase side channel of the economizer 25 through the throttle valve 26.

[0032] The outlet of the liquid phase flow channel of the economizer 25 is connected to the inlet of the expansion valve 27, and the outlet of the expansion valve 27 is connected to the inlet of the working fluid flow channel of the evaporator 21. The economizer 25 splits the condensed gas-liquid two-phase flow, with the gaseous working fluid entering the compressor and the liquid working fluid entering the expansion valve 27.

[0033] In one embodiment provided in this application, the outlet of the water side channel of the condenser 24 is connected to the inlet of the pressure reducing valve 31 of the steam flash unit 3, the inlet of the pure water of the flash tank 32 is connected to the outlet of the pressure reducing valve 31, the outlet of the steam of the flash tank 32 is connected to an external steam delivery pipeline, the outlet of the pure water of the flash tank 32 is connected to the inlet of the return water pump 34 through a three-way valve 33, and the inlet of the water side channel of the condenser 24 is connected to the outlet of the return water pump 34 of the steam flash unit 3.

[0034] Furthermore, the steam flash unit 3 is a subsystem for producing steam, consisting of a flash tank 32, a return water pump 34, and a pressure reducing valve 31. Pure water circulates between these three components. The flash tank 32 is the core component of the steam flash system. It suddenly reduces the pressure of the high-temperature, high-pressure pure water from the water-side pipe of the condenser 24, causing some of the liquid water to evaporate into high-temperature steam. The high-temperature steam flows out from the upper steam outlet of the flash tank 32, and the unevaporated liquid water flows out from the lower outlet of the flash tank. The return water pump 34 sends this unevaporated liquid water back to the water-side pipe of the condenser 24. The pressure reducing valve 31 is used to regulate the pressure of the pure water entering the flash tank 32.

[0035] In one embodiment provided in this application, the outlet of the water inlet valve 42 is connected to two pipes. One pipe is connected to the inlet of the cooling pipe of the DC / DC transformer 43, and the other pipe is connected to the inlet of the cooling pipe of the air compressor 17. The inlet of the water storage tank 41 is connected to two pipes. One pipe is connected to the outlet of the cooling pipe of the DC / DC transformer 43, and the other pipe is connected to the outlet of the cooling pipe of the air compressor 17. After passing through the water inlet valve 42, pure water enters the cooling water pipe of the air compressor 17. The inlet of the water side pipe of the air-water heat exchanger 44 is connected to the outlet of the water storage tank 41, and the outlet of the water side pipe of the air-water heat exchanger 44 is connected to the inlet of the water supply pump 45. The outlet of the water supply pump 45 is connected to the outlet of the flash tank 32 through the three-way valve 33.

[0036] The pure water added to the water replenishment unit 4 has two main functions: first, to recover the waste heat from the air compressor 17 and the exhaust gas; and second, to provide a water source for the steam flash unit 3 to ensure the continuous production of steam. The water inlet valve 42 controls the flow rate of the water replenishment. The water storage tank 41 can be used to store the water replenishment and also as a buffer tank. The air-water heat exchanger 44 recovers the exhaust gas waste heat through the water replenishment. Because the pipeline pressure of the steam flash unit 3 is very high, the water replenishment pump must be used to increase the water pressure in order to force the water replenishment into the circulating water pipeline of the steam flash unit 3.

[0037] In one embodiment provided in this application, the air-side flow channel outlet of the superheater 22 is connected to the air-side flow channel inlet of the expander 19 in the fuel cell unit 1, and the air-side pipe inlet of the air-water heat exchanger 44 is connected to the exhaust port of the expander 19.

[0038] In summary, by setting up a combined electric and steam power system for the recovery of waste heat from a proton exchange membrane fuel cell (PEMFC), a high-temperature heat pump and flash tank 32 are used to recover the waste heat of the PEMFC coolant to generate high-temperature steam. Simultaneously, all essential auxiliary components of the PEMFC system—air compressor 17, transformer, intercooler 16, etc.—are modified for heat recovery, and components such as catalytic burner 15 and expander 19 are added to recover the heat energy from incompletely burned hydrogen exhaust gas and the pressure energy of air. The direct current (DC) generated by this system is first converted into alternating current (AC) by an inverter and supplied to the heat pump unit 2 and the steam flash unit 3; the remaining electricity is transmitted to the power grid.

[0039] Reference Figures 1-3 This embodiment provides a simulation method for waste energy recovery from a proton exchange membrane fuel cell, calculating the energy utilization rate of the PEMFC combined power generation system according to the following formula: Among them, W p The power generation capacity of PEMFC; Q h For the heating capacity of a high-temperature heat pump; Δh H2 W represents the loss due to the enthalpy of hydrogen. c The electrical power consumed by the combined electric and gas power system.

[0040] Numerical simulation was used to calculate the system energy utilization rate of a PEMFC system without waste heat recovery, a PEMFC system with conventional waste heat recovery, and a PEMFC system with waste energy recovery, and the simulation results were compared.

[0041] Using 20 years of system operation as a timescale, the simulation comparison results are as follows: Figure 2 and Figure 3 As shown.

[0042] Comparison between PEMFC systems with waste heat recovery and PEMFC systems without waste heat recovery: 1. Energy Utilization Rate: The energy utilization rate of PEMFC systems without waste heat recovery is only about 0.4 to 0.6, resulting in a significant waste of energy. In contrast, the energy utilization rate of PEMFC systems with combined electric and gas power generation is 0.6 to 1.1, which is 50% to 90% higher than that of PEMFC systems without waste heat recovery, resulting in significant economic benefits.

[0043] 2. Temperature control effect: Since the heat pump evaporator is used as the cooler of PEMFC, its parameter stability is higher than that of the cooling tower that relies on air cooling, which helps the PEMFC system to operate stably and efficiently.

[0044] Comparison between PEMFC systems with waste energy recovery and conventional PEMFC systems with waste heat recovery: 1. Energy utilization rate: The energy utilization rate of conventional waste heat recovery PEMFC systems is about 0.6 to 0.8. The energy utilization rate of combined electric and steam power generation PEMFC systems is 0.6 to 1.1, which is 10% to 25% higher than that of conventional waste heat recovery PEMFC systems, resulting in higher economic benefits.

[0045] 2. Application Scenarios: The PEMFC (Power-Steam Combined Heat and Power) system can produce high-temperature steam, which can expand the heating scenario from building heating to the industrial field, adding a new revenue model for the waste heat utilization of the PEMFC system.

[0046] In summary, the air compressor 17 is connected to the cooling channel of the inlet valve 42, and water is used to recover the waste heat of the air compressor 17; the expander 19 is coaxially connected to the air compressor 17, and the exhaust gas of the expander drives the main shaft to rotate, recovering the kinetic energy of the air; the fuel cell stack 11 is connected to the evaporator 21 of the heat pump through its cooling channel, and deionized water circulates between the fuel cell stack 1 cooling channel and the heat pump evaporator 21, using the deionized water to remove the waste heat of the fuel cell and provide it to the heat pump as a heat source; the heat pump's superheater 22 and the catalytic converter... The system is connected to a combustion burner 15 to heat air using the heat energy from the combustion of hydrogen exhaust gas. The air then supplies heat to the heat pump, recovering the enthalpy of the hydrogen exhaust gas. An air-water heat exchanger 44 is connected to an expander 19 and a water storage tank 41 to recover waste heat from the air and heat the makeup water. A flash tank 32 is connected to a heat pump condenser 24 to absorb heat from the heat pump and produce steam. A makeup water pump 45 is connected to the circulating water pipe of the steam flash unit to send the water that has absorbed waste heat into the heat pump condenser 24. This setup significantly improves the system's energy efficiency.

[0047] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A combined power and steam power system for recovering waste energy from a proton exchange membrane fuel cell, characterized in that: include, Fuel cell unit (1); and, A heat pump unit (2) connected to the fuel cell unit (1); and, A steam flash evaporation unit (3) connected to the heat pump unit (2); and, A water replenishment unit (4) connected to the fuel cell unit (1) and the steam flash unit (3); The fuel cell unit (1) provides a heat source for the heat pump unit (2); the steam flash unit (3) absorbs the heat from the heat pump to produce steam; the water replenishment unit (4) recovers the waste heat from the air, heats the water, and delivers the water that has absorbed the waste heat to the heat pump unit (2) through the steam flash unit (3).

2. The combined power and steam power system for waste energy recovery from a proton exchange membrane fuel cell according to claim 1, characterized in that: The fuel cell unit (1) includes a stack (11), the input end of the anode of the stack (11) is connected to the output end of the ejector circulation unit (12), the input end of the ejector circulation unit (12) is connected to the output end of the proportional valve (13), and the input end of the proportional valve (13) is connected to the hydrogen storage tank.

3. The combined power and steam power system for waste energy recovery from a proton exchange membrane fuel cell according to claim 2, characterized in that: The output end of the anode of the fuel cell stack (11) is connected to the input end of the exhaust valve (14), and the output end of the exhaust valve (14) is connected to the catalytic burner (15).

4. The combined power and steam power system for waste energy recovery from a proton exchange membrane fuel cell according to claim 3, characterized in that: The input end of the cathode of the fuel cell stack (11) is connected to the output end of the intercooler (16), the input end of the intercooler (16) is connected to the output end of the air compressor (17); the output end of the cathode of the fuel cell stack (11) is connected to the catalytic combustor (15).

5. The combined power and steam power system for waste energy recovery from a proton exchange membrane fuel cell according to claim 4, characterized in that: The heat pump unit (2) includes an evaporator (21) connected to the output end of the cooling channel of the fuel cell stack (11). The output end of the evaporator (21) is connected to the input end of a circulating pump (18), and the output end of the circulating pump (18) is connected to the cooling channel of the fuel cell stack (11).

6. The combined power and steam power system for waste energy recovery from a proton exchange membrane fuel cell according to claim 5, characterized in that: The output end of the evaporator (21) is connected to the input end of the superheater (22). The output end of the superheater (22) is connected to the high-pressure inlet of the vapor injection enthalpy compressor (23). The low-pressure outlet of the vapor injection enthalpy compressor (23) is connected to the input end of the condenser (24). The output end of the condenser (24) has two branches, one of which is connected to the input end of the economizer (25), and the other branch is connected to the input end of the economizer (25) through the throttle valve (26). The output end of the economizer (25) is connected to the input end of the expansion valve (27). The output end of the expansion valve (27) is connected to the input end of the evaporator (21). The medium-pressure inlet of the vapor injection enthalpy compressor (23) is connected to the output end of the economizer (25).

7. The combined power and steam power system for waste energy recovery from a proton exchange membrane fuel cell according to claim 6, characterized in that: The steam flash unit (3) includes a pressure reducing valve (31) connected to the output end of the condenser (24). The output end of the pressure reducing valve (31) is connected to the input end of the pure water of the flash tank (32). The output end of the steam of the flash tank (32) is connected to the steam delivery pipeline. The output end of the pure water of the flash tank (32) is connected to the input end of the return water pump (34) through a three-way valve (33). The output end of the return water pump (34) is connected to the input end of the condenser (24).

8. The combined power and steam power system for waste energy recovery from a proton exchange membrane fuel cell according to claim 7, characterized in that: The water replenishment unit (4) includes a water storage tank (41) connected to the output end of the cooling pipe of the air compressor (17). The input end of the cooling pipe of the air compressor (17) is connected to the output end of the water inlet valve (42). The output end of the water inlet valve (42) is also connected to the input end of the cooling pipe of the DC / DC transformer (43). The output end of the cooling pipe of the DC / DC transformer (43) is connected to the input end of the water storage tank (41). The output end of the water storage tank (41) is connected to the input end of the air-water heat exchanger (44). The output end of the air-water heat exchanger (44) is connected to the input end of the water replenishment pump (45). The output end of the water replenishment pump (45) is connected to the output end of the flash tank (32) through a three-way valve (33).

9. The combined power and steam power system for waste energy recovery from a proton exchange membrane fuel cell according to claim 8, characterized in that: The output end of the superheater (22) is connected to the input end of the expander (19), and the exhaust port of the expander (19) is connected to the input end of the air-water heat exchanger (44).

10. The combined power and steam power system for waste energy recovery from a proton exchange membrane fuel cell according to claim 9, characterized in that: The air compressor (17) is coaxially connected to the expander (19).

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