Fuel cell system with high-temperature self-leakage detection function and leakage detection method

Abstract

The invention discloses a fuel cell system with a high-temperature self-leakage detection function and a leakage detection method. The system is characterized in that natural gas sequentially passes through a fuel gas inlet switch valve and an electric pile fuel gas side inlet BOP and then enters an electric pile fuel gas side, and then sequentially passes through an electric pile fuel gas side outlet BOP, a fuel gas cooler and a fuel gas tail gas switch valve and then enters a combustor; a cold area pressure sensor is arranged between the fuel gas inlet switch valve and the fuel gas side inlet BOP of the electric pile; hot area pressure sensors are respectively arranged at the inlet and the outlet of the fuel gas side of the electric pile, or the hot area pressure sensors are respectively arranged at the inlet and the outlet of the fuel gas side of the electric pile and the inlet of the fuel gas cooler. Whether leakage occurs or not is judged according to the leakage rate, and automatic leakage detection of the fuel cell system is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell system with a high-temperature self-leak detection function and a leak detection method. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Solid oxide fuel cells are third-generation fuel cells. They are all-solid-state chemical power generation devices that directly convert the chemical energy stored in fuel and oxidant into electrical energy in an efficient and environmentally friendly manner at medium and high temperatures. Solid oxide fuel cells have the highest operating temperature and are classified as high-temperature fuel cells.

[0004] Solid oxide fuel cells have the characteristics of high efficiency and wide fuel adaptability among various fuel cells. In order to ensure its long-term continuous operation, it is necessary to regularly conduct leak detection on the battery stack, high-temperature heat exchanger and pipe seals in the system. Since leak detection belongs to the scope of operation and maintenance, the current common solution is for the operation and maintenance personnel to transport the leak detector to the site and perform leak detection when the system is cold. However, high-temperature fuel cells are generally expected to work continuously. Even if they are occasionally shut down, users do not want them to cool down to a cold state, which results in too long a time for cold start again.

[0005] The prior art discloses a solid oxide fuel cell leak detection method, which determines whether the object under test is leaking by the flow rate after the pressure of three pressure sensors is stabilized, and obtains the leakage value. However, for objects with high temperature and changing temperature, the pressure of the leak detection system is often difficult to stabilize, resulting in the method being difficult to implement and the detection results being inaccurate. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes a fuel cell system and a leak detection method with a high-temperature self-leak detection function, which performs leak detection according to the size of the leak rate at different measurement positions, thereby realizing regional online leak detection of the system.

[0007] In some embodiments, the following technical solutions are adopted:

[0008] A fuel cell system with a high-temperature self-leak detection function, comprising:

[0009] The natural gas enters the fuel cell gas side after passing through the fuel cell gas inlet switch valve and the fuel cell gas side inlet BOP in sequence, and then enters the burner after passing through the fuel cell gas side outlet BOP, the gas cooler, and the fuel cell gas tail switch valve in sequence;

[0010] A cold zone pressure sensor is provided between the gas inlet switch valve and the fuel cell stack gas side inlet BOP;

[0011] Hot zone pressure sensors are respectively arranged at the inlet and outlet positions of the fuel cell stack fuel gas side, or, hot zone pressure sensors are respectively arranged at the inlet and outlet positions of the fuel cell stack fuel gas side and the inlet position of the fuel gas cooler.

[0012] As a further solution, it also includes: a pre-valve temperature sensor is arranged between the gas cooler and the gas tail gas switch valve.

[0013] As a further solution, the pre-valve temperature sensor is used to monitor the gas temperature entering the gas exhaust switch valve, and the gas temperature is controlled by a gas cooler to always remain within the tolerance range of the gas exhaust switch valve.

[0014] As a further solution, a hot zone pressure sensor is arranged at the fuel cell stack gas side inlet, specifically between the fuel cell stack gas side inlet BOP and the fuel cell stack gas side inlet.

[0015] As a further solution, a hot zone pressure sensor is arranged at the fuel cell stack gas side outlet, specifically between the fuel cell stack gas side outlet and the fuel cell stack gas side outlet BOP.

[0016] As a further solution, a hot zone pressure sensor is arranged at the inlet of the gas cooler, specifically between the fuel cell stack gas side outlet BOP and the inlet of the gas cooler.

[0017] In other embodiments, the following technical solutions are adopted:

[0018] A leak detection method for a fuel cell system with a high-temperature self-leak detection function, comprising:

[0019] When the fuel cell system is in shutdown state, close the gas exhaust switch valve and open the gas intake switch valve;

[0020] Natural gas is injected into the fuel cell system through the gas inlet switch valve;

[0021] If the pressure value detected by the cold zone pressure sensor reaches the set first pressure value P0 within the set time t0, the gas inlet switch valve is closed, and the voltage values ​​detected by the cold zone pressure sensor and each hot zone pressure sensor are recorded; after a static time t1, the voltage values ​​detected by the cold zone pressure sensor and each hot zone pressure sensor are recorded again, the leakage rate of each pressure measurement position is calculated, and whether the fuel cell system is leaking is determined based on the leakage rate, and the leakage position is determined;

[0022] If the pressure value detected by the cold zone pressure sensor does not reach the first pressure value P0 within the set time t0, it is determined that a leakage fault occurs in the fuel cell system, and the operation is stopped and an alarm is issued.

[0023] Wherein, the first pressure value P0 is determined according to the minimum value of the maximum pressure boundaries of all components of the system;

[0024] The set time t0 is obtained by calculation:

[0025] Where n0 is the standard gas supply flow rate, R is the universal gas constant, T is the system temperature, r0 is the standard leakage rate, and V is the cavity volume through which the gas flows;

[0026] The time t1 is the time during which the system can maintain pressure at the standard leakage rate r0.

[0027] As a further solution, the leakage rate at each pressure measurement location is calculated as follows:

[0028]

[0029] Among them, r is the leakage rate at the measuring point, P and T are the initial pressure and temperature of the measuring point at the beginning of standing, and P′ and T′ are the pressure and temperature of the measuring point after standing time t1.

[0030] When the leakage rate r is less than or equal to the standard leakage rate r0, it means that there is no leakage near the measuring point; when the leakage rate r is greater than the standard leakage rate r0, it means that there is leakage near the measuring point; if the leakage rates r of two adjacent measuring points are both greater than the standard leakage rate r0, the measuring point with a larger leakage rate is closer to the leakage point.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention sets pressure sensors at different positions as pressure measurement points, calculates the leakage rate of each measurement point by the pressure change at each measurement point in a closed state, and determines whether a leakage occurs by the leakage rate, thereby realizing automatic leak detection of the fuel cell system.

[0033] (2) The detection process of the scheme of the present invention does not need to maintain stable pressure, does not require the help of external detection equipment, is not affected by high temperature environment, and does not need to cool the fuel cell system to a cold state before detection, thereby improving the detection efficiency and ensuring that the fuel cell can be quickly put into normal working state.

[0034] (3) The leakage detection method of the present invention is simple and easy to implement, can obtain accurate leakage detection results, and can distinguish between minor leakage and major leakage, so that the staff can determine the maintenance strategy in time.

[0035] Other features and advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of the structure of a fuel cell system with a high-temperature self-leak detection function according to an embodiment of the present invention;

[0037] Figure 2 is a flow chart of a leak detection method in an embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram of a natural gas injection process in an embodiment of the present invention;

[0039] Among them, 100. gas intake switch valve, 200. cold zone pressure sensor, 301. first hot zone pressure sensor, 302. second hot zone pressure sensor, 303. third hot zone pressure sensor, 400. gas cooler, 500. pre-valve temperature sensor, 600. gas exhaust switch valve. DETAILED DESCRIPTION

[0040] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0041] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0042] Embodiment 1

[0043] In one or more embodiments, a fuel cell system with a high temperature self-leak detection function is disclosed, combined with Figure 1 , including:

[0044] The natural gas enters the fuel cell stack gas side after passing through the fuel cell stack gas inlet switch valve 100, the flow meter, and the fuel cell stack gas side inlet BOP in sequence, and then enters the burner after passing through the fuel cell stack gas side outlet BOP, the gas cooler 400, and the gas tail gas switch valve 600 in sequence. The natural gas and the air transported by the air branch are mixed and burned in the burner, and the heat generated is recovered through the burner outlet side BOP, and the exhaust gas after combustion is discharged into the atmosphere.

[0045] In this embodiment, a cold zone pressure sensor 200 is provided between the fuel gas inlet switch valve and the fuel cell stack fuel gas side inlet BOP, for monitoring the pressure of the fuel cell stack fuel gas side in the cold state.

[0046] In some embodiments, a first hot zone pressure sensor 301 and a second hot zone pressure sensor 302 are respectively arranged at the inlet and outlet positions of the fuel cell stack gas side, and are respectively used to monitor the pressure of the high temperature section of the fuel cell stack gas side; as a specific example, the first hot zone pressure sensor is arranged between the fuel cell stack gas side inlet BOP and the fuel cell stack gas side inlet, and the second hot zone pressure sensor is arranged between the fuel cell stack gas side outlet and the fuel cell stack gas side outlet BOP.

[0047] In other embodiments, a first hot zone pressure sensor and a second hot zone pressure sensor are respectively arranged at the inlet and outlet positions of the fuel cell stack gas side, and the specific arrangement method is the same as described above; at the same time, a third hot zone pressure sensor 303 is arranged at the inlet position of the gas cooler; as a specific example, the third hot zone pressure sensor is arranged between the BOP on the outlet side of the fuel cell stack gas side and the inlet of the gas cooler.

[0048] In this embodiment, the cold zone pressure sensor refers to the pressure of the cold fluid, and the hot zone pressure sensor refers to the pressure of the hot fluid, which are existing products. In this embodiment, when leak detection is performed, the positions of the cold zone pressure sensor and each hot zone pressure sensor are respectively used as the measurement point positions.

[0049] In this embodiment, a pre-valve temperature sensor 500 is arranged between the gas cooler and the gas exhaust switch valve to monitor the temperature of the gas entering the gas exhaust switch valve. The gas cooler and the pre-valve temperature sensor are used in combination. Based on the temperature data detected by the pre-valve temperature sensor, the gas temperature is controlled by the gas cooler to always be kept within the tolerance range of the gas exhaust switch valve; normally, the control temperature of the gas cooler is 100-200°C, 80-180°C or 200-300°C, etc., which can be set according to actual needs, mainly to ensure that the gas exhaust switch valve has long-term durability and reliability within the control temperature range.

[0050] It should be noted that the BOP (Balance Of Plant) in this embodiment refers to the heat balance system. The BOP at the inlet of the fuel cell gas side, the BOP at the outlet of the fuel cell gas side, the BOP at the outlet of the burner, and the BOPs on the air branch are a coordinated and coupled whole, which is used to achieve heat control of the entire system; for example: the function of the BOP at the inlet of the fuel cell gas side is to heat the low-temperature natural gas to a set high-temperature state; the function of the BOP at the outlet of the fuel cell gas side is to cool the high-temperature natural gas to a set low-temperature state; the BOP at the outlet of the burner is used to cool the combustion temperature and couple the remaining heat to the BOP at the inlet of the fuel cell gas side and the BOP of the air branch. BOP is a prior art in the field of fuel cells and will not be described in detail.

[0051] The system of this embodiment can monitor the pressure change at each measuring point by setting pressure sensors at different measuring points, and then calculate the leakage rate according to the pressure change to realize leakage detection of the fuel cell.

[0052] Embodiment 2

[0053] In one or more embodiments, a leak detection method for a fuel cell system with a high temperature self-leak detection function is disclosed, combined with Figure 2 and Figure 3 , specifically including the following process:

[0054] S101: When the fuel cell system is in a shutdown state, the gas exhaust switch valve is closed and the gas intake switch valve is opened.

[0055] In this embodiment, the fuel cell system is in a shutdown state, which may refer to a cold state where the system has not started running, at which time the system is at room temperature; it may also refer to a state where the system stops generating electricity and stops supplying gas after running at high temperature, at which time the system is in a high temperature state.

[0056] S102: Natural gas is injected into the fuel cell system through the gas intake switch valve.

[0057] S103: If the pressure value detected by the cold zone pressure sensor reaches the set first pressure value P0 within the set time t0, the gas inlet switch valve is closed, the pressure change of the cold zone pressure sensor and each hot zone pressure sensor is monitored, the leakage rate of each measuring point is calculated based on the pressure change, and whether the fuel cell system is leaking is determined based on the leakage rate, and the leakage position is determined;

[0058] S104: If the pressure value detected by the cold zone pressure sensor does not reach the first pressure value P0 within the set time t0, the gas intake switch valve is closed, it is determined that a serious leak occurs in the fuel cell system, and an alarm is issued.

[0059] As a specific example, combining Figure 3 The natural gas injection process in step S103 is as follows:

[0060] S1031: Open the gas intake switch valve, and inject natural gas into the fuel cell system through the gas intake switch valve; monitor the pressure value detected by the cold zone pressure sensor in real time, and when the pressure value reaches the set first pressure value P0, stop the gas injection and close the gas intake switch valve; record the voltage values ​​detected by the cold zone pressure sensor and each hot zone pressure sensor at this time, as well as the temperature value monitored by the pre-valve temperature sensor.

[0061] S1032: After the system has been stationary for time t1, the voltage values ​​monitored by the cold zone pressure sensor and each hot zone pressure sensor, as well as the temperature value monitored by the pre-valve temperature sensor are recorded again.

[0062] In this embodiment, the first pressure value P0 is determined according to the minimum value of the maximum pressure boundaries of all components of the system, that is, among the maximum pressure boundaries borne by all components, the minimum value is selected.

[0063] The set time t0 is obtained by calculation:

[0064] where n0 is the standard gas supply flow rate; R is the universal gas constant; T is the system temperature; r0 is the standard leakage rate; V is the volume of the channel through which the gas flows, generally obtained by measurement; t0 is the shortest time corresponding to the first pressure value P0.

[0065] The time t1 is the time during which the system can maintain pressure at the standard leakage rate r0; assuming that at the standard leakage rate r0, after the static time t1, the pressure at the corresponding measurement point is P1; when the leakage rate r is greater than the standard leakage rate r0, as the gas leaks, the measured point pressure P will be less than P1 within the time t1, and at this time the system leaks. When r is less than or equal to the standard leakage rate r0, as the gas leaks, the measured point pressure P will not be less than P1 within the time t1, and at this time the system is determined to be normal.

[0066] S1033: Calculate the leakage rate at each pressure measurement position. The specific calculation formula is as follows:

[0067] Calculating the leakage rate at each pressure measurement position specifically is:

[0068]

[0069] where r is the leakage rate at the measurement point position, P and T are respectively the initial pressure and temperature at the measurement point at the start of static state, and P' and T' are respectively the pressure and temperature at the measurement point after the static time t1.

[0070] S1034: Determine whether the fuel cell system leaks based on the leakage rate r, and determine the leakage location.

[0071] Specifically, when r < r0, it indicates that there is no leakage near the measurement point position; when r > r0, it indicates that there is leakage near the measurement point position; if the leakage rates r of two adjacent measurement point positions are both greater than r0, the measurement point with the larger leakage rate is closer to the leakage point.

[0072] The method of this embodiment is not affected by the temperature of the fuel cell system, and there is no need to cool the fuel cell system to a cold state before testing. This solves the problem of being unable to perform leak detection in a high temperature environment, improves the detection efficiency, and enables the fuel cell to be quickly put into normal working state. No additional external equipment is required during the detection process, the operation process is simple, accurate leak detection results can be obtained, and slight leaks and serious leaks can be distinguished, so that the staff can determine the maintenance strategy in a timely manner.

[0073] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A fuel cell system with a high-temperature self-leakage detection function, characterized in that: include: The natural gas enters the fuel cell gas side after passing through the fuel cell gas inlet switch valve and the fuel cell gas side inlet BOP in sequence, and then enters the burner after passing through the fuel cell gas side outlet BOP, the gas cooler, and the fuel cell gas tail switch valve in sequence; A cold zone pressure sensor is provided between the gas inlet switch valve and the fuel cell stack gas side inlet BOP; Hot zone pressure sensors are respectively arranged at the inlet and outlet positions of the fuel cell stack fuel gas side, or, hot zone pressure sensors are respectively arranged at the inlet and outlet positions of the fuel cell stack fuel gas side and the inlet position of the fuel gas cooler.

2. A fuel cell system with a high temperature self-leakage detection function as claimed in claim 1, characterized in that: Also includes: A pre-valve temperature sensor is arranged between the gas cooler and the gas tail gas switch valve.

3. A fuel cell system with a high temperature self-leakage detection function as claimed in claim 2, characterized in that: The pre-valve temperature sensor is used to monitor the temperature of the gas entering the gas tail gas switch valve, and the gas temperature is controlled by the gas cooler to always remain within the tolerance range of the gas tail gas switch valve.

4. A fuel cell system with a high temperature self-leakage detection function as claimed in claim 1, characterized in that: The hot zone pressure sensor is arranged at the fuel cell stack gas side inlet position, specifically, between the fuel cell stack gas side inlet BOP and the fuel cell stack gas side inlet.

5. A fuel cell system with a high temperature self-leakage detection function as claimed in claim 4, characterized in that: The hot zone pressure sensor is arranged at the fuel cell stack gas side outlet, specifically between the fuel cell stack gas side outlet and the fuel cell stack gas side outlet BOP.

6. A fuel cell system with a high temperature self-leakage detection function as claimed in claim 5, characterized in that: The hot zone pressure sensor is arranged at the inlet of the gas cooler, specifically between the gas side outlet BOP of the fuel cell stack and the inlet of the gas cooler.

7. A leak detection method for a fuel cell system with a high-temperature self-leak detection function, characterized in that: include: When the fuel cell system is in shutdown state, close the gas exhaust switch valve and open the gas intake switch valve; Natural gas is injected into the fuel cell system through the gas inlet switch valve; If the pressure value detected by the cold zone pressure sensor reaches the set first pressure value P0 within the set time t0, the gas inlet switch valve is closed, and the voltage values ​​detected by the cold zone pressure sensor and each hot zone pressure sensor are recorded; after a static time t1, the voltage values ​​detected by the cold zone pressure sensor and each hot zone pressure sensor are recorded again, the leakage rate of each pressure measurement position is calculated, and whether the fuel cell system is leaking is determined based on the leakage rate, and the leakage position is determined; If the pressure value detected by the cold zone pressure sensor does not reach the first pressure value P0 within the set time t0, it is determined that a leakage fault occurs in the fuel cell system, and the system stops running and issues an alarm.

8. A leak detection method for a fuel cell system with a high-temperature self-leak detection function as claimed in claim 7, characterized in that: The first pressure value P0 is determined according to the minimum value of the maximum pressure boundaries of all components of the system; The set time t0 is obtained by calculation: Where n0 is the standard gas supply flow rate, R is the universal gas constant, T is the system temperature, r0 is the standard leakage rate, and V is the cavity volume through which the gas flows; The time t1 is the time during which the system can maintain pressure at the standard leakage rate r0.

9. A leak detection method for a fuel cell system with a high-temperature self-leak detection function as claimed in claim 7, characterized in that: Calculate the leakage rate at each pressure measurement location as follows: Among them, r is the leakage rate at the measuring point, P and T are the initial pressure and temperature of the measuring point at the beginning of standing, and P′ and T′ are the pressure and temperature of the measuring point after standing time t1.

10. A leak detection method for a fuel cell system with a high-temperature self-leak detection function as claimed in claim 7, characterized in that: Determine whether the fuel cell system is leaking based on the leak rate and determine the leak location, specifically: When the leakage rate r is less than or equal to the standard leakage rate r0, it means that there is no leakage near the measuring point; when the leakage rate r is greater than the standard leakage rate r0, it means that there is leakage near the measuring point; if the leakage rates r of two adjacent measuring points are both greater than the standard leakage rate r0, the measuring point with a larger leakage rate is closer to the leakage point.

Images