A solid oxide fuel cell stack temperature control system and control method

Abstract

The invention discloses a temperature control system and control method for a solid oxide fuel cell stack, which realizes full utilization of thermal energy and real-time control of the operating temperature of the stack. The system comprises a solid oxide fuel cell stack, wherein the anode air inlet of the solid oxide fuel cell stack is connected to a fuel storage chamber through a fuel air inlet pipe, a first solenoid valve is provided on the fuel air inlet pipe, a cathode air inlet of the solid oxide fuel cell stack is connected to a compressed air storage chamber through an air air inlet pipe, a fifth solenoid valve is provided on the air air inlet pipe, a heating bypass is provided on the air inlet pipe, the heating bypass is connected to the fifth solenoid valve, an electric heating device and a sixth solenoid valve are provided on the heating bypass, and an exhaust gas discharge port of the solid oxide fuel cell stack is connected to a third solenoid valve, an exhaust gas pump and an external heating device in sequence through an exhaust pipe.

Description

Technical Field

[0001] The present invention relates to the technical field of solid oxide fuel cells, and in particular to a solid oxide fuel cell stack temperature control system and a control method. Background Art

[0002] Currently, there is a lack of systems for SOFC battery stack temperature detection, temperature control and exhaust heat recovery. The power generation efficiency of solid oxide fuel cells is only about 50%. The stack generates a lot of heat when working and most of the heat is dissipated by the exhaust gas after the reaction. The stack reaction needs to be within a suitable temperature range. A system that monitors the temperature of the stack at all times and responds quickly to temperature changes is particularly important. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a solid oxide fuel cell stack temperature control system and control method to maintain the stack operating temperature within a range that is beneficial to promoting the reaction, and to assist an external heat source in supplying energy for the stack startup, thereby achieving full utilization of thermal energy and real-time control of the stack operating temperature.

[0004] The object of the present invention is achieved in that:

[0005] A solid oxide fuel cell stack temperature control system and control method, including a solid oxide fuel cell stack, wherein an anode air inlet of the solid oxide fuel cell stack is connected to a fuel storage chamber via a fuel inlet pipe, a first solenoid valve is provided on the fuel inlet pipe, a cathode air inlet of the solid oxide fuel cell stack is connected to a compressed air storage chamber via an air inlet pipe, a fifth solenoid valve is provided on the air inlet pipe, a heating bypass is provided on the air inlet pipe, the heating bypass is connected to the fifth solenoid valve, an electric heating device and a sixth solenoid valve are provided on the heating bypass, an air flow control pipe is connected between the downstream ends of the fuel inlet pipe and the air inlet pipe, a fourth solenoid valve is provided on the air flow control pipe, and an exhaust gas discharge port of the solid oxide fuel cell stack is connected to a third solenoid valve, an exhaust gas pump and an external heating device in sequence via an exhaust pipe.

[0006] Preferably, the outer shell surface of the solid oxide fuel cell stack is covered with a jacket device and an electric heating device, the jacket device is connected to a heat exchange circuit, the heat exchange circuit is provided with a liquid metal pressure pump, a shell and tube heat exchanger, and a second solenoid valve, the jacket device is embedded with a plurality of liquid metal conduits, and the plurality of liquid metal conduits are connected to the heat exchange circuit.

[0007] Preferably, the upstream end of the shell and tube heat exchanger is connected with a header to reduce thermal deviation, so that the working fluid is heated evenly and has better fluidity and thermal performance.

[0008] A control method for a solid oxide fuel cell stack temperature control system,

[0009] When the stack is initially preheated, the first solenoid valve, the third solenoid valve, and the sixth solenoid valve, the electric heating device, and the heating function of the jacket device are turned on. The compressed air storage chamber outputs compressed air. After the air is heated to a certain temperature by the electric heating device, it enters the cathode of the battery stack. The fuel storage chamber outputs hydrogen to provide a reducing atmosphere for the anode to prevent the anode from being oxidized by oxygen and reducing the anode material during the heating process. The hydrogen is then discharged by the third solenoid valve. At the same time, the jacket device heats the stack. When the solid oxide fuel cell stack is heated to the operating temperature, the electric heating device and the third solenoid valve, the sixth solenoid valve, and the heating function of the jacket device are turned off. At this point, the initial preheating process is completed.

[0010] During normal operation, the first solenoid valve, the third solenoid valve, the fifth solenoid valve and the exhaust pump are opened, and the fuel and compressed air enter the solid oxide fuel cell stack through the first solenoid valve and the fifth solenoid valve respectively, and the exhaust gas generated by the reaction is discharged to the external heating equipment through the third solenoid valve;

[0011] When the temperature of the solid oxide fuel cell stack exceeds the operating temperature and continues to rise, the second solenoid valve and the liquid metal pressure pump are opened, the tail gas pump is turned on, and the power of the tail gas pump is adjusted, and the heat of the solid oxide fuel cell stack is taken away by circulating the normal temperature fuel, compressed air and the liquid metal in the jacket device, thereby achieving a cooling effect;

[0012] When the temperature of the solid oxide fuel cell stack is lower than the operating temperature and continues to decrease, the second solenoid valve, the exhaust gas pump and the liquid metal pressure pump are closed to allow the heat generated by the stack system to be used to increase the stack temperature until the stack is stabilized within the target temperature range.

[0013] Preferably, a PC is used to collect and process the detected temperature information and intelligently control the system devices, and the self-locking function of the PLC ladder diagram is used to make the initial preheating, heating and cooling three processes that do not interfere with each other and will not run at the same time, so that the system temperature can achieve dynamic balance.

[0014] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0015] 1. The present invention is to place multiple temperature sensors on the battery stack to accurately monitor the temperature, use the temperature information input to make instructions to the PLC after being processed by the PC, and design an initial preheating system to facilitate providing the environmental temperature requirements required for the initial reaction;

[0016] 2. The liquid metal cooler is designed using the stack jacket. The jacket is embedded with parallel pipes to increase the heating area. Using low-temperature liquid metal as the heat storage medium can quickly cool the system. Rapid cooling is conducive to the stability of the stack temperature and maximizes the stack output power. The absorbed heat can be used for heating through the heat exchanger.

[0017] 3. The jacket device is the core of the system to achieve temperature control and maintain the stability of the working temperature of the fuel cell stack, preventing the temperature from changing too quickly and causing thermal expansion and contraction, which may damage the fuel cell stack packaging and cause leakage, thereby extending the service life of the fuel cell stack, maintaining a stable working temperature and improving the efficiency of the fuel cell stack in producing electricity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the present invention;

[0019] Figure 2 Schematic diagram of the shell and tube heat exchanger used in the present invention.

[0020] Reference numerals

[0021] In the accompanying drawings, 1-fuel storage chamber; 2-first solenoid valve; 3-jacket device; 4-solid oxide fuel cell stack; 5-liquid metal pressure pump; 6-shell and tube heat exchanger; 7-second solenoid valve; 8-external heating equipment; 9-exhaust gas pump; 10-third solenoid valve; 11-fourth solenoid valve; 12-electric heating device; 13-sixth solenoid valve; 14-fifth solenoid valve; 15-compressed air storage chamber. DETAILED DESCRIPTION

[0022] See also Figure 1 , is a temperature control system for a solid oxide fuel cell stack, comprising a solid oxide fuel cell stack 4, wherein the anode air inlet of the solid oxide fuel cell stack 4 is connected to a fuel storage chamber 1 through a fuel air inlet pipe, and a first solenoid valve 2 is provided on the fuel air inlet pipe, and the cathode air inlet of the solid oxide fuel cell stack 4 is connected to a compressed air storage chamber 15 through an air air inlet pipe, and a fifth solenoid valve 14 is provided on the air inlet pipe, and a heating bypass is provided on the air inlet pipe, and the heating bypass is connected to the fifth solenoid valve 14, and an electric heating device 12 and a sixth solenoid valve 13 are provided on the heating bypass, and an air flow control pipe is connected between the downstream ends of the fuel inlet pipe and the air inlet pipe, and a fourth solenoid valve 11 is provided on the air flow control pipe, and the exhaust gas discharge port of the solid oxide fuel cell stack 4 is connected to a third solenoid valve 10, an exhaust gas pump 9, and an external heating device 8 in sequence through an exhaust pipe.

[0023] The surface of the solid oxide fuel cell stack 4 is covered with a jacket device 3, and a heat exchange circuit is connected to the jacket device 3. The heat exchange circuit is provided with a liquid metal pressure pump 5, a shell and tube heat exchanger 6, and a second solenoid valve 7. The jacket device 3 is embedded with a plurality of liquid metal conduits, and the plurality of liquid metal conduits are connected to the heat exchange circuit. Many liquid metal conduits are embedded in the outer jacket of the stack. Such an arrangement can maximize the heat exchange efficiency and quickly control the temperature; the external heating equipment is a direct heating equipment such as a radiator. The heated pipe of the shell and tube heat exchanger is connected to another heating device or a cold source. Figure 2 In the embodiment, another heating device reuses the exhaust gas discharged by the external heating device 8 as a heating medium.

[0024] The upstream end of the shell and tube heat exchanger is connected with a header to reduce thermal deviation, so that the working fluid is heated evenly and has better fluidity and thermal performance.

[0025] A control method for a solid oxide fuel cell stack temperature control system:

[0026] When the stack is initially preheated, the first solenoid valve 2, the third solenoid valve 10 and the sixth solenoid valve 13 are opened. Hydrogen is a reducing gas introduced into the anode during initial preheating to provide a reducing environment and anode reduction. The jacket device 3 heats the solid oxide fuel cell stack 4 to a high temperature state (700-800°C). When the stack is heated to the target temperature, the heating function of the jacket 3, the electric heating device 12, the third solenoid valve 10 and the sixth solenoid valve 13 are closed, and the heating process is completed;

[0027] During normal operation, the first solenoid valve 2, the third solenoid valve 10, the fifth solenoid valve 14, and the exhaust gas pump 9 are opened, and the fuel and compressed air enter the stack through the first solenoid valve 2 and the fifth solenoid valve 14 respectively. The fourth solenoid valve 11 restricts the air and fuel from mixing, and the fuel and air enter the anode and cathode respectively. The PC records and analyzes the stack temperature every minute. When the temperature of the solid oxide fuel cell stack 4 exceeds the operating temperature and continues to rise, the second solenoid valve 7 is opened, the power of the exhaust gas pump 9 is increased, and the exhaust gas is used entirely for the external heating equipment 8, and the normal temperature fuel gas is used to take away the internal heat of the system to achieve the effect of cooling. When the temperature of the stack is lower than the operating temperature, the second solenoid valve 7 and the liquid metal pressure pump 5 are closed to allow the heat generated by the stack system to be used to increase the temperature of the stack until the temperature of the stack stabilizes within an appropriate range. Heating and cooling will not be performed at the same time, and the temperature of the system is dynamically balanced. The self-locking of the PLC ladder diagram makes the initial preheating, heating and cooling three independent processes.

[0028] Directly control the PC program writing, the PC processes the received signal to control the PLC's thermal cycle system and recycle the high-quality dissipated heat energy.

[0029] The technical problems to be solved by the present invention are the startup heating problem of the high-temperature solid oxide fuel cell stack, the self-maintenance of the temperature of the battery stack under normal working conditions, and the utilization of high-temperature tail gas. The processing object is the high-calorie tail gas, and the liquid metal jacket system is used to maintain the working temperature of the battery stack, which is conducive to promoting the reaction. The tail gas is directly used for heating in other aspects. By controlling the PLC by PC, the thermal balance of the SOFC system is dynamically and intelligently achieved.

[0030] The present invention uses PC / PLC as the core of automatic control, and uses a liquid metal with low melting point and large thermal conductivity as a heat storage medium to control the temperature of the solid oxide fuel cell (SOFC) system, maintain the operating temperature of the stack within a range that is beneficial to promoting the reaction, and assist an external heat source to supply energy for the stack startup, thereby achieving full utilization of thermal energy and real-time control of the stack operating temperature.

[0031] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A control method for a temperature control system of a solid oxide fuel cell stack, characterized in that: A solid oxide fuel cell stack temperature control system comprises a solid oxide fuel cell stack, wherein an anode air inlet of the solid oxide fuel cell stack is connected to a fuel storage chamber via a fuel air inlet pipe, a first solenoid valve is provided on the fuel air inlet pipe, a cathode air inlet of the solid oxide fuel cell stack is connected to a compressed air storage chamber via an air air inlet pipe, a fifth solenoid valve is provided on the air air inlet pipe, a heating bypass is provided on the air inlet pipe, the heating bypass is connected in parallel with the fifth solenoid valve, an electric heating device and a sixth solenoid valve are provided on the heating bypass, and an exhaust gas discharge port of the solid oxide fuel cell stack is sequentially connected to a third solenoid valve, an exhaust gas pump and an external heating device via an exhaust pipe; The surface of the solid oxide fuel cell stack is covered with a jacket device, the jacket device is connected to a heat exchange circuit, the heat exchange circuit is provided with a liquid metal pressure pump, a shell and tube heat exchanger, and a second solenoid valve, the jacket device is embedded with a plurality of liquid metal conduits, and the plurality of liquid metal conduits are connected to the heat exchange circuit; An electric heater is provided in the jacket device, and the electric heater is used to heat the solid oxide fuel cell stack to an operating temperature; An air flow control pipe is connected between the downstream ends of the fuel intake pipe and the air intake pipe, and a fourth solenoid valve is provided on the air flow control pipe; The stack is initially preheated, the first solenoid valve, the third solenoid valve, the sixth solenoid valve, the electric heating device and the electric heater in the jacket device are opened, the compressed air storage chamber outputs compressed air, the air is heated to the set temperature by the electric heating device, and then enters the cathode of the solid oxide fuel cell stack, the fuel storage chamber outputs hydrogen to provide a reducing atmosphere for the anode of the solid oxide fuel cell stack to prevent the anode from being oxidized by oxygen and reducing the anode material during the heating process, and then it is discharged by the third solenoid valve, and at the same time the jacket device heats the stack, when the solid oxide fuel cell stack is heated to the operating temperature, the electric heating device and the third solenoid valve, the sixth solenoid valve, and the electric heater in the jacket device are closed, and the initial preheating process is completed; During normal operation, the first solenoid valve, the third solenoid valve, the fifth solenoid valve and the exhaust pump are opened, and the fuel and compressed air enter the solid oxide fuel cell stack through the first solenoid valve and the fifth solenoid valve respectively, and the exhaust gas generated by the reaction is discharged to the external heating equipment through the third solenoid valve; When the temperature of the solid oxide fuel cell stack exceeds the operating temperature and continues to rise, the second solenoid valve and the liquid metal pressure pump are opened to increase the power of the tail gas pump, and the heat of the solid oxide fuel cell stack is taken away by circulating the normal temperature fuel, compressed air and the liquid metal in the jacket device, thereby achieving a cooling effect; When the temperature of the solid oxide fuel cell stack is lower than the operating temperature and continues to decrease, the second solenoid valve, the exhaust gas pump and the liquid metal pressure pump are closed to allow the heat generated by the stack system to be used to increase the stack temperature until the stack is stabilized within the target temperature range.

2. The control method of a solid oxide fuel cell stack temperature control system according to claim 1, characterized in that: The solid oxide fuel cell stack has a built-in temperature sensor, and a PC is used to collect and process the temperature information detected by the temperature sensor. The PC is connected to various system devices through a PLC, and the self-locking function of the PLC ladder diagram is used to make the initial preheating, heating and cooling three processes that do not interfere with each other and will not run at the same time, so that the temperature of the system can achieve a dynamic balance.

3. A solid oxide fuel cell stack temperature control system according to claim 1, characterized in that: The upstream end of the shell and tube heat exchanger is connected with a header to reduce thermal deviation, so that the working fluid is heated evenly and has better fluidity and thermal performance.

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