Fuel cell system

Abstract

The utility model relates to the technical field of fuel cells, in particular to a fuel cell system which comprises a humidifier, a back pressure valve, a shunting module, an air inlet system, an electric pile, an expansion machine and a tail exhaust, the expansion machine is communicated with the tail exhaust; a dry air inlet port of the humidifier is communicated with an air outlet end of the air inlet system, and the humidifier is communicated with the electric pile; the air inlet end of the back pressure valve is communicated with the exhaust port of the humidifier; the shunting module is provided with two groups of passages which are respectively communicated with the back pressure valve and the expansion machine, one group of passages is opened when the fuel cell system is less than or equal to the set drainage power, and the other group of passages is opened when the fuel cell system is greater than the set drainage power. By controlling the opening and closing states of the two groups of passages of the shunting module, the flow direction of gas exhausted from the cathode of the electric pile can be reasonably distributed, the overall energy utilization rate can be improved, and the reliability of the expansion machine can be guaranteed.

Description

Technical Field

[0001] This utility model relates to the field of fuel cell technology, and specifically to a fuel cell system. Background Technology

[0002] The market demand for high-power fuel cell systems is increasing, but the power consumption of the Base-of-Pack (BOP) has become a major concern for system integrators. The largest source of power consumption in the BOP is the air compressor. To reduce parasitic power consumption in the air compressor, system integrators often use expanders, such as turbo expanders (air compressors with energy recovery), to recover energy from the exhaust gas discharged from the fuel cell stack cathode outlet, thereby reducing the overall power consumption of the air compressor. However, because the exhaust gas from the fuel cell stack may contain a large amount of water, it can impact the turbine and the overall shaft system, negatively affecting the reliability of the entire system over time. To avoid this potential problem, some system manufacturers typically install a cathode water separator at the point from the fuel cell stack outlet to the turbine inlet in the system's air path to reduce the amount of liquid water entering the turbine, thus better protecting the expander.

[0003] However, adding a cathode water separator at the cathode outlet to the turbine inlet of the system has a drawback: it increases the overall system volume and flow resistance, reduces the expansion ratio, and thus affects the recovery effect, failing to minimize the overall power consumption of the air compressor. Although adding a cathode air-water separator reduces the impact of water vapor on the air compressor, the overall system performance is affected, the turbine's work is reduced, resulting in a decrease in the overall net output power of the system and a decline in economic efficiency. Utility Model Content

[0004] The purpose of this invention is to address the problems existing in the background technology by proposing a fuel cell system.

[0005] The technical solution of this utility model: A fuel cell system, including an intake system, a stack, an expander, and a tailpipe; the expander and the tailpipe are connected; and further includes...

[0006] Humidifier; its dry air inlet is connected to the air outlet of the air inlet system, and the humidifier is connected to the fuel cell stack.

[0007] Back pressure valve; its inlet end is connected to the exhaust port of the humidifier;

[0008] The shunt module has two sets of passages that connect to the back pressure valve and the expander, respectively. One set of passages is used to open when the fuel cell system's drainage power is less than or equal to the set value, and the other set of passages is used to open when the fuel cell system's drainage power is greater than the set value.

[0009] Preferably, a set of passages includes a switch valve A installed on the pipeline; the inlet of switch valve A is connected to the outlet of the back pressure valve, and the outlet of switch valve A is connected to the inlet of the expander.

[0010] Preferably, another set of passages includes a switch valve B installed on the pipeline and a separation device for gas-liquid separation;

[0011] The back pressure valve, switch valve B, separation device and expander are connected in sequence.

[0012] Preferably, the liquid outlet of the separation device is connected to the tail drain.

[0013] Preferably, it also includes a three-way valve; the outlet of the back pressure valve is connected to the inlet of the switching valve A and the inlet of the switching valve B respectively through the three-way valve.

[0014] Compared with the prior art, the above-mentioned technical solution of this utility model has the following beneficial technical effects:

[0015] This invention can rationally allocate the flow direction of the gas discharged from the cathode of the fuel cell stack by controlling the opening and closing states of the two sets of passages of the diversion module, which can improve the overall energy utilization rate and ensure the reliability of the expander.

[0016] The switching parameters of the shunt module can be adjusted according to customer needs and actual operating conditions; the energy recovery method can also be adjusted according to customer needs and actual operating conditions. It can directly select to bypass the cathode moisture, or it can make the gas discharged from the cathode outlet of the fuel cell completely pass through gas-water separation before entering the expander vortex end to do work. Attached Figure Description

[0017] Figure 1 This is a flowchart of one embodiment of the present invention. Detailed Implementation

[0018] like Figure 1 As shown, the present invention proposes a fuel cell system including a humidifier, a back pressure valve, a shunt module, an air intake system, a fuel cell stack, an expander, and a tailpipe; the expander and the tailpipe are connected.

[0019] The intake system is a conventional structure for existing fuel cell systems. Its main task is to provide sufficient air to the fuel cell to meet the needs of the chemical reaction. As it is a mature technology, it will not be described in detail. The outlet of the intake system is connected to the dry intake port of the humidifier through a pipeline. After the outside air is processed by the intake system, the dry air enters the dry inlet of the humidifier through the intake system. The humidifier is connected to the fuel cell stack through a pipeline so that the fuel cell stack exhaust enters from the wet inlet of the humidifier and then exits from the wet outlet. The intake end of the back pressure valve is connected to the exhaust port of the humidifier through a pipeline.

[0020] The diversion module has two sets of passages, namely passage A and passage B, which connect the back pressure valve and the expander respectively:

[0021] Passage A is used to open when the fuel cell system is less than or equal to the set drainage power. Passage A includes a switch valve A installed on the pipeline. The inlet of switch valve A is connected to the outlet of the back pressure valve, and the outlet of switch valve A is connected to the inlet of the expander.

[0022] Passage B is used to open when the fuel cell system is in a state where the drainage power is greater than the set value; passage B includes a switch valve B installed on the pipeline and a separation device for gas-liquid separation.

[0023] The back pressure valve, switch valve B, separation device, and expander are connected in sequence; the outlet of the back pressure valve is connected to the inlet of switch valve A and the inlet of switch valve B through a three-way valve A; the outlet of switch valve B is connected to the inlet of the separation device through a pipeline; the outlet of the separation device is connected to the inlet of the expander through a pipeline; and the liquid outlet of the separation device is connected to the tail drain through a pipeline.

[0024] In one optional embodiment, the air inlet of the expander is connected to the air outlet of the separator and the outlet of the switching valve A via a three-way valve B; the inlet of the tail section is connected to the liquid outlet of the separator and the liquid outlet of the expander via a three-way valve C; and the connection of the pipeline is controlled by installing solenoid valves on the above pipelines, depending on the system selection.

[0025] Before using the fuel cell system provided by this utility model, the parameters for switching valves A and B to open, i.e., the set drainage power value, are first tested based on the parameters of the fuel cell system. Specifically, a humidity sensor is installed in the pipeline between the back pressure valve and the shunt module, and this pipeline is transparent. During normal operation of the fuel cell system (i.e., the fuel cell system operates at rated power, and the intake system normally delivers gas), the humidity sensor detects a humidity value X, and there are no obvious liquid droplets on the inner wall of the transparent pipeline. The power of the fuel cell system is gradually increased until the power of the fuel cell system reaches P1, which is recorded as the drainage power under the pipeline switching state. Obvious liquid water droplets were observed on the inner wall of the transparent pipe, at which point the humidity sensor detected a humidity value of X1. Therefore, in the fuel cell system, when the humidity value detected by the humidity sensor is greater than or equal to X1, or the power of the fuel cell system is greater than or equal to P1, switch valve B is activated and switch valve A is closed. This allows the gas mixture discharged from the cathode to completely pass through the separation device to separate the cathode moisture before entering the expander vortex end to perform work. Conversely, switch valve A is activated and switch valve B is closed, allowing the gas mixture discharged from the cathode to completely enter the expander turbine end to perform work. In this way, the energy recovery effect of the entire machine is ensured, and the impact of cathode exhaust on the turbine is reduced, thereby ensuring the reliability of the entire machine.

[0026] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A fuel cell system, comprising an intake system, a stack, an expander, and a tailpipe; the expander and the tailpipe are connected; characterized in that, Also includes Humidifier; its dry air inlet is connected to the air outlet of the air inlet system, and the humidifier is connected to the fuel cell stack. Back pressure valve; its inlet end is connected to the exhaust port of the humidifier; The shunt module has two sets of passages that connect to the back pressure valve and the expander, respectively. One set of passages is used to open when the fuel cell system's drainage power is less than or equal to the set value, and the other set of passages is used to open when the fuel cell system's drainage power is greater than the set value.

2. The fuel cell system according to claim 1, characterized in that, A set of passages includes a switch valve A installed on the pipeline; the inlet of switch valve A is connected to the outlet of the back pressure valve, and the outlet of switch valve A is connected to the inlet of the expander.

3. A fuel cell system according to claim 2, characterized in that, Another set of pathways includes a switch valve B installed on the pipeline and a separation device for gas-liquid separation; The back pressure valve, switch valve B, separation device and expander are connected in sequence.

4. A fuel cell system according to claim 3, characterized in that, The liquid outlet of the separation device is connected to the tail drain.

5. A fuel cell system according to claim 3, characterized in that, It also includes a three-way valve; the outlet of the back pressure valve is connected to the inlet of switch valve A and the inlet of switch valve B respectively through the three-way valve.

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