Fuel cell waste heat utilization system

Abstract

The utility model discloses a fuel cell waste heat utilization system which is characterized in that an ejector is arranged in a tail exhaust air pipeline, the tail end of the tail exhaust air pipeline is connected with a water tank, an ejection port and an outlet of the ejector are connected into the tail exhaust air pipeline, the ejection port is close to a fuel cell stack, and the outlet is close to the water tank; a water return pipe is further connected between the water tank and the inlet of the ejector, and a water pump is arranged on the water return pipe; and water in the water return pipe is driven by the water pump to pass through the ejector and is mixed with exhaust air entering from the ejection opening for heat exchange. According to the fuel cell waste heat utilization system disclosed by the utility model, water can be heated by utilizing heat of high-temperature and high-humidity air at an electric pile outlet through the arrangement of the water return pipe and the ejector. In addition, high-temperature steam and cold water are fully mixed, and the heat exchange efficiency is higher than that of a non-contact heat exchanger. Meanwhile, water in high-humidity air at the outlet of the galvanic pile can be synchronously recycled, and water vapor is cooled after heat exchange to generate liquid water to be recycled.

Description

Technical Field

[0001] The utility model belongs to the technical field of fuel cells, and in particular relates to a fuel cell waste heat utilization system. Background Art

[0002] Combined heat and power is a direction with broad application prospects for fuel cells in the stationary field. It uses the power generation technology of fuel cells to provide electricity and heat to the user at the same time. The combined heat and power system can use both the electricity generated by fuel cells and the waste heat generated during the operation of the fuel cell system to improve the energy utilization efficiency of the fuel cell system.

[0003] In the existing fuel cell cogeneration system, as described in the utility model with authorization announcement number CN218918959U, a heat exchanger, a hot water storage tank and a water pump are connected in sequence to form a circulation loop to recover the heat taken away by the coolant when the fuel cell system is running.

[0004] However, when the fuel cell system is running, the temperature of the exhaust gas from the fuel cell can generally reach 80-85°C, and the exhaust gas from the fuel cell contains a large amount of liquid water, hydrogen that has not completely participated in the reaction, and saturated steam. There is currently no suitable solution for efficiently utilizing the heat in the exhaust gas from the fuel cell and the discharged liquid water and hydrogen that has not completely participated in the reaction. Utility Model Content

[0005] The utility model aims at the above-mentioned deficiencies in the prior art and provides a fuel cell waste heat utilization system.

[0006] A fuel cell waste heat utilization system comprises a fuel cell stack, the fuel cell stack having an air inlet and an air outlet, the air outlet being connected to a tail exhaust air pipeline, the end of the tail exhaust air pipeline being connected to a water tank, an ejector being arranged in the tail exhaust air pipeline, the ejector having an inlet, an outlet and an ejection port, the ejection port and the outlet of the ejector being connected to the tail exhaust air pipeline, the ejection port being close to the fuel cell stack, and the outlet being close to the water tank;

[0007] A water return pipe is also connected between the water tank and the inlet of the ejector, and a water pump is provided on the water return pipe;

[0008] When the water in the return water pipe passes through the ejector driven by the water pump, it is mixed with the tail exhaust air in the tail exhaust air pipeline entering from the ejection port to perform heat exchange.

[0009] Preferably, the air inlet is connected to an air intake pipeline, the air intake pipeline is connected to an air compressor, an air filter is provided upstream of the air compressor, an intercooler is provided downstream of the air compressor, and the air intake pipeline is provided with a first back pressure valve between the intercooler and the air inlet.

[0010] Preferably, a dehydrogenator is provided on the exhaust air pipeline at one end of the ejector close to the fuel cell stack for catalytically oxidizing the hydrogen mixed in the exhaust air to generate water. The dehydrogenator uses catalytic combustion to catalytically burn the hydrogen that has not completely participated in the reaction at the stack outlet to release heat, thereby increasing the temperature of the air entering the waste heat recovery device.

[0011] More preferably, the tail exhaust air pipeline is provided with a second back pressure valve at one end close to the fuel cell stack; and a check valve is provided between the hydrogen remover and the second back pressure valve.

[0012] Preferably, the end of the tail exhaust air pipeline is connected to the upper part of the water tank, and the return water pipe is connected to the bottom of the water tank.

[0013] Preferably, the top surface of the water tank is also provided with an exhaust valve for exhausting air.

[0014] Beneficial effects of the utility model:

[0015] (1) The utility model fuel cell waste heat utilization system can utilize the heat of the high-temperature and high-humidity air at the outlet of the fuel cell stack to heat water through the arrangement of the return pipe and the ejector. In addition, the high-temperature steam and cold water are fully mixed, and the heat exchange efficiency is higher than that of the non-contact heat exchanger.

[0016] (2) At the same time, the water in the high-humidity air at the outlet of the battery stack can be recovered synchronously, and the water vapor in the air is also cooled down after heat exchange to generate liquid water for recovery.

[0017] (3) The waste heat utilization system is a purely mechanical component and has a more reliable structure than moving parts such as expanders. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the fuel cell waste heat utilization system of the utility model.

[0019] Figure numerals: air filter 1, air compressor 2, intercooler 3, first back pressure valve 4, fuel cell stack 5, second back pressure valve 6, check valve 7, hydrogen dehydrogenator 8, ejector 9, water pump 10, water tank 11, exhaust valve 12. DETAILED DESCRIPTION

[0020] like Figure 1As shown, a fuel cell waste heat utilization system includes a fuel cell stack 5, the fuel cell stack 5 has an air inlet and an air outlet, the air inlet is connected to an air inlet pipeline, the air inlet pipeline is connected to an air compressor 2, an air filter 1 is provided upstream of the air compressor 2, an intercooler 3 is provided downstream of the air compressor 2, and the air inlet pipeline is provided with a first back pressure valve 4 between the intercooler 3 and the air inlet of the fuel cell stack 5. In the present application, the upstream and downstream of the air inlet pipeline are distinguished by the air flow direction, the upstream is far away from the fuel cell stack 5, and the downstream is close to the fuel cell stack 5.

[0021] The air outlet of the fuel cell stack 5 is connected to the tail exhaust air pipeline, the end of the tail exhaust air pipeline is connected to the water tank 11, and the tail exhaust air pipeline is provided with an ejector 9, the ejector 9 has an inlet, an outlet and an ejection port, the ejection port and the outlet of the ejector 9 are connected to the tail exhaust air pipeline, the ejection port is close to the fuel cell stack 5, and the outlet is close to the water tank 11. A return water pipe is also connected between the water tank 11 and the inlet of the ejector 9, and a water pump 10 is provided on the return water pipe. When the water in the return water pipe passes through the ejector 9 driven by the water pump 10, it is mixed with the tail exhaust air in the tail exhaust air pipeline entering from the ejection port for heat exchange.

[0022] By setting up the return pipe and the ejector 9, the heat of the high-temperature and high-humidity air at the outlet of the stack can be used to heat the water. In addition, the high-temperature steam and the cold water are fully mixed, and the heat exchange efficiency is higher than that of the non-contact heat exchanger. Thus, the heat in the tail exhaust air can be effectively recovered. The water in the water tank 11 reaches a certain temperature and can be used for other applications. At the same time, the water in the high-humidity air at the outlet of the stack can be synchronously recovered, and the water vapor therein is also cooled down to generate liquid water after heat exchange and is recovered.

[0023] A dehydrogenator is provided on the tail exhaust air pipeline at one end of the ejector 9 near the fuel cell stack 5 for catalytically oxidizing the hydrogen mixed in the tail exhaust air to generate water. The dehydrogenator uses catalytic combustion to catalytically burn the hydrogen that has not completely participated in the reaction at the stack outlet to release heat, thereby increasing the temperature of the air entering the waste heat recovery device. The structure of the dehydrogenator can adopt the structure in the prior art, and the existing finished product can be directly purchased.

[0024] The tail exhaust air pipeline is provided with a second back pressure valve 6 at one end close to the fuel cell stack 5. A check valve 7 is provided between the hydrogen remover 8 and the second back pressure valve 6.

[0025] The end of the tail exhaust air pipeline is connected to the upper part of the water tank 11, preferably connected to the upper part of the liquid level of the water tank 11. The return pipe is connected to the bottom of the water tank 11. The water entering the water tank 11 from the tail exhaust air pipeline is the water with higher temperature after heat exchange, while the water with lower temperature in the water tank 11 is at the bottom of the water tank 11. Connecting the return pipe to the bottom of the water tank 11 can utilize the water with lower temperature to exchange heat with the tail exhaust air, thereby improving the efficiency of heat exchange.

[0026] The top surface of the water tank 11 is also provided with an exhaust valve 12 for exhausting. The exhaust valve 12 is used to exhaust the air in the tail exhaust air, and the air is discharged from the exhaust valve 12 after entering the water tank.

Claims

1. A fuel cell waste heat utilization system, comprising a fuel cell stack, wherein the fuel cell stack has an air inlet and an air outlet, characterized in that: The air outlet is connected to a tail exhaust air pipeline, the end of the tail exhaust air pipeline is connected to a water tank, an ejector is provided in the tail exhaust air pipeline, the ejector has an inlet, an outlet and an ejection port, the ejection port and the outlet of the ejector are connected to the tail exhaust air pipeline, the ejection port is close to the fuel cell stack, and the outlet is close to the water tank; A water return pipe is also connected between the water tank and the inlet of the ejector, and a water pump is provided on the water return pipe; When the water in the return water pipe passes through the ejector driven by the water pump, it is mixed with the tail exhaust air in the tail exhaust air pipeline entering from the ejection port to perform heat exchange.

2. The fuel cell waste heat utilization system according to claim 1, characterized in that: The air inlet is connected to an air inlet pipeline, the air inlet pipeline is connected to an air compressor, an air filter is provided upstream of the air compressor, an intercooler is provided downstream of the air compressor, and the air inlet pipeline is provided with a first back pressure valve between the intercooler and the air inlet.

3. The fuel cell waste heat utilization system according to claim 1, characterized in that: A hydrogen remover is provided on the tail exhaust air pipeline at one end of the ejector close to the fuel cell stack for catalytically oxidizing hydrogen mixed in the tail exhaust air to generate water.

4. The fuel cell waste heat utilization system according to claim 3, characterized in that: The tail exhaust air pipeline is provided with a second back pressure valve at one end close to the fuel cell stack; a check valve is provided between the hydrogen remover and the second back pressure valve.

5. The fuel cell waste heat utilization system according to claim 1, characterized in that: The end of the tail exhaust air pipeline is connected to the upper part of the water tank, and the return water pipe is connected to the bottom of the water tank.

6. The fuel cell waste heat utilization system according to claim 1, characterized in that: The top surface of the water tank is also provided with an exhaust valve for exhausting air.

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