A molten carbonate fuel cell stack

Abstract

The present application relates to molten carbonate fuel cell technology field, specifically to a kind of molten carbonate fuel cell stack, comprising: cell stack body, pneumatic pressurizing piece and air passage piece.In calcination to molten carbonate fuel cell stack, since the temperature in the top of calcination equipment is higher than the temperature in the bottom, cell stack body starts to settle from top, by fixing upper pressing plate, let lower pressing plate rise to compensate the pressure loss caused by cell stack body settlement when calcination, make the displacement of cell stack body top drop from bottom offset, keep upper pressing plate unchanged in horizontal direction, can avoid upper pressing plate tilt offset with cell stack body settlement, can effectively avoid the risk of electrolyte leakage caused by cell stack body tilt, cell stack body in situ calcination in place, improve the quality of cell stack after calcination.

Description

Technical Field

[0001] The present invention relates to the technical field of molten carbonate fuel cells, and in particular to a molten carbonate fuel cell stack. Background Art

[0002] A fuel cell is a power generation device that converts the chemical energy of a fuel directly into electrical energy through an electrochemical reaction. This reaction does not involve combustion, so the energy conversion efficiency is not limited by the Carnot cycle. When a fuel cell is operating, hydrogen or other fuel is fed to the anode. An electrochemical reaction occurs at the interface between the electrode and the electrolyte, where the hydrogen or other fuel is oxidized and oxygen is reduced, generating an electric current and outputting electrical energy.

[0003] A molten carbonate battery stack is assembled by stacking multiple molten carbonate single cell sheets. When the battery stack is assembled and in-situ calcined, as the temperature rises, the organic matter in the diaphragm decomposes and the electrolyte salt becomes molten, the height of the battery stack will change. The battery stack pressurizing device needs to adjust the pressure in time according to the internal state of the battery sheet to avoid inconsistent sedimentation rates of the front and back of the battery stack body and position deviation.

[0004] The prior art provides pressure compensation for a molten carbonate fuel cell stack by installing locking bolts at the four corners. However, because stack sedimentation occurs during the firing process, the top temperature of the stack is higher and the bottom temperature is lower. Under the influence of the high temperature at the top of the stack, one end of the locking bolt deforms due to its own internal force, causing it to stretch. This causes the pressure compensation value applied by the locking bolts to the stack to deviate from the preset value, making it impossible to correct the tilt of the stack after sedimentation, and the stack cannot be properly fired in situ, affecting the quality of the stack after firing. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect in the prior art that the cell stack is not fully baked in situ when the cell stack is baked while applying pre-pressure to the molten carbonate fuel cell stack using locking bolts, thereby providing a molten carbonate fuel cell stack.

[0006] In order to solve the above technical problems, the present invention provides a molten carbonate fuel cell stack, comprising:

[0007] The battery stack body is equipped with an upper pressure plate and a lower pressure plate on its upper and lower sides respectively. A force sensor is installed between the upper pressure plate and the battery stack body to measure the pressure between the upper pressure plate and the battery stack body.

[0008] A pneumatic pressure member having a fixed member and a pressure member that are slidably fitted, an upper pressure plate mounted on the fixed member, and a lower pressure plate mounted on the pressure member, a pressure chamber with a sealed arrangement being provided on the fixed member, at least one end of the pressure member extending into the pressure chamber, and a biasing member mounted on the other end for applying a biasing force to the pressure member toward the pressure chamber;

[0009] The vent is connected to the pressure chamber and is used to ventilate the pressure chamber to adjust the biasing force applied by the biasing member to the pressure member, and to control the pressure value measured by the force sensor to remain within a preset range.

[0010] Optionally, multiple groups of pneumatic pressure members are provided, one end of the pneumatic pressure member is mounted on the edge of the upper pressure plate, and the other end is mounted on the edge of the lower pressure plate, and the battery stack body is arranged between the multiple groups of pneumatic pressure members.

[0011] Optionally, a plurality of pneumatic pressurizing members are symmetrically arranged around the battery stack body.

[0012] Optionally, the biasing member is an elastic member, and the elastic member is kept in a compressed state to apply a pushing force to the pressure applying member toward the pressure applying chamber.

[0013] Optionally, the elastic member is a pressure spring.

[0014] Optionally, a thermal insulation layer is provided on the top of the upper pressing plate.

[0015] Optionally, the pneumatic pressurizing member further includes a supporting member, and the bottom of the fixing member is fixedly mounted on the supporting member.

[0016] Optionally, a control component is further included, and the ventilator and the force sensor are both electrically connected to the control component.

[0017] Optionally, a sliding cavity is provided in the fixing member, one end of the sliding cavity is connected to the pressure chamber, the pressure member and the sliding cavity are slidably matched, and a seal is provided between the pressure member and the inner wall of the sliding cavity, and the biasing member is installed in the sliding cavity.

[0018] Optionally, the pressure member is a sliding column, the lower pressing plate is fixedly connected to the sliding column, and a clearance groove for the lower pressing plate to move up and down is provided on the fixing member.

[0019] The technical solution of the present invention has the following advantages:

[0020] 1. The molten carbonate fuel cell stack provided by the present invention comprises: a battery stack body, on the upper and lower sides of which are respectively installed an upper pressure plate and a lower pressure plate, a force sensor is installed between the upper pressure plate and the battery stack body, and the force sensor is used to measure the pressure between the upper pressure plate and the battery stack body; a pneumatic pressure member, which has a sliding fitting fixing member and a pressure member, the upper pressure plate is installed on the fixing member, and the lower pressure plate is installed on the pressure member, and a sealed pressure chamber is provided on the fixing member, at least one end of the pressure member extends into the pressure chamber, and the other end is installed with a biasing member, and the biasing member is used to apply a biasing force toward the pressure chamber to the pressure member; a vent member, which is connected to the pressure chamber and is used to ventilate the pressure chamber to adjust the biasing force applied by the biasing member on the pressure member, and control the pressure value measured by the force sensor to remain within a preset range.

[0021] When a molten carbonate fuel cell stack is baked, the entire stack is placed in a baking device. As the temperature rises, the organic matter in the diaphragm decomposes and the electrolyte salt becomes molten, causing the height of the stack body to change and settle. During the settling process, the thickness of the stack body gradually decreases, the pressure between the upper pressure plate and the stack body gradually decreases, and the pressure value measured by the force sensor gradually decreases. At the same time, the vent member inflates or evacuates air into the pressure chamber, and in conjunction with the biasing force of the biasing member, adjusts the length of the pressure member in the pressure chamber, thereby controlling the gradual rise of the lower pressure plate to offset the pressure loss caused by the settling of the stack body. The position of the lower pressure plate is adjusted in real time based on the feedback value of the force sensor to ensure that the pressure values ​​applied to the stack body by the upper and lower pressure plates during the baking process are within a preset range, so that the tilt of the stack body after settlement can be corrected in a timely manner. Since the top temperature in the baking equipment is higher than the bottom temperature, the battery stack body starts to settle from the top. By fixing the upper pressure plate and allowing the lower pressure plate to rise to compensate for the pressure loss caused by the settlement of the battery stack body during baking, the downward displacement of the top of the battery stack body is offset from the bottom, keeping the upper pressure plate unchanged in the horizontal direction, and avoiding the upper pressure plate from tilting and offsetting as the battery stack body settles. The risk of electrolyte leakage caused by the tilt of the battery stack body can be effectively avoided. The battery stack body is baked in situ, thereby improving the quality of the battery stack after baking.

[0022] 2. The molten carbonate fuel cell stack provided by the present invention comprises multiple sets of pneumatic pressure members, one end of which is mounted on the edge of the upper platen and the other end on the edge of the lower platen. The stack body is positioned between these sets of pneumatic pressure members. By positioning these sets of pneumatic pressure members in multiple directions around the stack body and controlling the rise of the lower platen to control the pressure applied to the stack body, the uniformity of the horizontal force applied to the stack body can be improved, thereby enhancing the firing quality of the stack body.

[0023] 3. In the molten carbonate fuel cell stack provided by the present invention, the biasing member is an elastic member, which remains compressed to apply a thrust to the pressure member toward the pressure chamber. By configuring the biasing member as an elastic member, the pressure chamber is ventilated or evacuated to apply thrust to one end of the pressure member, while the compression of the elastic member itself applies thrust to the other end. Controlling the pressure member requires adjusting the amount of gas in the pressure chamber to adjust its position, thereby controlling the position of the lower pressure plate. This facilitates control and adjustment of the lower pressure plate's position.

[0024] 4. The molten carbonate fuel cell stack provided by the present invention has a thermal insulation layer disposed on top of the upper pressure plate. This thermal insulation layer insulates the top of the stack body, reduces heat loss, and improves the baking efficiency of the stack body. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 Schematic diagram of the structure of a molten carbonate fuel cell stack provided in an embodiment of the present invention.

[0027] Figure 2 Schematic diagram of the structure of the pneumatic pressure member provided in an embodiment of the present invention.

[0028] Explanation of the accompanying symbols: 1. Battery stack body; 2. Upper pressure plate; 3. Lower pressure plate; 4. Fixing member; 5. Pressure member; 6. Pressure chamber; 7. Biasing member; 8. Support base; 9. Gap groove; 10. Vent; 11. Electronic control cabinet; 12. Thermal insulation layer; 13. Temperature rising and roasting device. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0032] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] Example

[0034] like Figure 1 and Figure 2 The figure shows a molten carbonate fuel cell stack provided in this embodiment, which includes: a fuel cell stack body 1, a pneumatic pressurizing member, a vent member and a control assembly.

[0035] An upper pressure plate 2 and a lower pressure plate 3 are respectively installed on the upper and lower sides of the battery stack body 1. A force sensor is installed between the upper pressure plate 2 and the battery stack body 1. The force sensor is used to measure the pressure between the upper pressure plate 2 and the battery stack body 1. The force sensor is fixedly installed on the bottom surface of the upper pressure plate 2. The pneumatic pressure member has a sliding fixed member 4 and a pressure member 5. The upper pressure plate 2 is installed on a fixed rod serving as the fixed member 4, and the lower pressure plate 3 is installed on the pressure member 5. The fixed member 4 is provided with a sealed pressure chamber 6. At least one end of the pressure member 5 extends into the pressure chamber 6, and the other end is provided with a biasing member 7. The biasing member 7 is used to apply a biasing force to the pressure member 5 toward the pressure chamber 6. A sliding chamber is provided in the fixed member 4. One end of the sliding chamber is connected to the pressure chamber 6. The pressure member 5 slides with the sliding chamber, and the pressure member 5 is sealed against the inner wall of the sliding chamber. The biasing member 7 is installed in the sliding chamber. The pressure member 5 is a sliding column, and the lower pressure plate 3 is fixedly connected to the sliding column. The fixing member 4 is provided with a clearance groove 9 for the lower pressure plate 3 to move up and down. The bottom of the fixing member 4 is fixedly mounted on a support base 8 as a support member. The clearance groove 9 is provided on one side of the sliding cavity, and the lower pressure plate 3 is connected to the sliding column in the clearance groove 9.

[0036] In this embodiment, the vent member is a vent 10, which is connected to the air port of an external air pump and communicates with the pressure chamber 6. Vent 10 is used to ventilate or exhaust air into the pressure chamber 6, thereby adjusting the biasing force applied by the biasing member 7 to the pressure member 5 and controlling the pressure value measured by the force sensor to remain within a preset range. The vent member and the force sensor are both electrically connected to an electronic control cabinet 11, which serves as a control component. The electronic control cabinet 11 adjusts the ventilation or exhaust state of the air pump based on the pressure value fed back by the force sensor.

[0037] In this embodiment, the biasing member 7 is a pressure spring, which acts as an elastic member. The pressure spring remains compressed to apply a thrust to the pressure member 5 toward the pressure chamber 6. To improve the thermal insulation performance of the battery stack body 1, an insulating layer 12 is provided on top of the upper pressure plate 2. In other embodiments, the biasing member 7 can also be an electric cylinder, electrically connected to the electronic control cabinet 11 to control its extension and contraction range. Alternatively, the biasing member 7 can be a pressure-applying elastic rubber, which acts as an elastic member.

[0038] Multiple sets of pneumatic pressure elements are provided, one end of each element being mounted on the edge of the upper platen 2 and the other end being mounted on the edge of the lower platen 3. The battery stack body 1 is positioned between these sets of pneumatic pressure elements. In this embodiment, four sets of pneumatic pressure elements are provided, symmetrically arranged around the battery stack body 1. Specifically, the four sets of pressure elements can be positioned at the four corners of the cubical battery stack body 1 or at the midpoints of the four sides of the cubical battery stack body 1.

[0039] To address the pressure loss of the molten carbonate fuel cell stack under high-temperature operating conditions and control the force magnitude and force application location, a pneumatic pressurizer is used to compensate for the pressure loss under high-temperature conditions by converting the pressure energy of the gas into mechanical energy. The pneumatic pressurizer can sensitively sense the settlement distance of the battery stack body 1 under high-temperature operating conditions, and the force is applied at the four sides. When the battery stack body 1 sinks unevenly on the left and right, the four groups of force application points control the compensation pressure separately according to its settlement situation, keeping the battery stack body 1 descending smoothly and avoiding safety hazards such as leakage caused by tilting the battery stack. The pneumatic control of the pneumatic pressurizer controls the rise of the lower pressure plate 3 from the bottom to compensate for the pressure, which can avoid the failure of the pneumatic pressurizer body due to slight deformation at high temperatures.

[0040] When the battery stack body is being roasted, the battery cells are stacked on a support base to form the battery stack body. After the battery stack body is assembled, the battery stack body is embedded between the upper and lower pressure plates of the pneumatic pressure member. The outside of the battery stack body is a temperature-raising roasting device 13. When high-temperature roasting begins, the battery stack body will settle. The sinking distance will be converted into a pressure value acting on the force sensor. The electronic control cabinet adjusts the position of the lower pressure plate in the pneumatic pressure member according to the feedback value of the force sensor, compensating from below for the pressure loss of the battery stack body caused by the settlement. During the roasting process of the battery stack body, gas is continuously introduced into the temperature-raising roasting device. N2 protection or H2 reduction is selected according to different functions. Pressure gauges are added at the cathode and anode tail gas ports. After roasting is completed, N2 is introduced to both the anode and cathode sides to maintain pressure for half an hour, and the tail gas valve is closed. If the pressure gauges on both sides do not drop, there will be no gas leakage and the sealing effect is good. When the battery stack body begins to settle during in-situ baking, the force sensor in the pneumatic pressure component will sense the pressure loss caused by the sinking, and then control the air pump through the electronic control cabinet to evacuate the pressure chamber, allowing the pressure spring to extend, and use the pressure column to drive the lower base plate to rise, thereby achieving pressure compensation.

[0041] When testing the sealing effect of the battery stack body, the battery stack sealing effect is measured by calculating the battery stack gas leakage value. The formula for calculating gas leakage is:

[0042] L=(P f -P i )V / P i ΔtC

[0043] Where P f is the final pressure of the gas; P i is the initial pressure of the gas; Δt is the time corresponding to the pressure change; C is the circumference of the battery; V is the volume of the gas cylinder; L is the leakage rate, ensuring L ≤ 0.1cm 3 min －1 cm －1 .

[0044] Example corresponding to experimental data

[0045] <![CDATA[阳极通入N2 10min]]> Battery stack specification Anode pressure gauge display value Leak rate <![CDATA[O.1MPa,V=4.76m 3 ]]> 58 cm * 34 cm * 100 sections 0.106 MPa 0.05 <![CDATA[阳极极通入N2 30min]]> Battery stack specification Anode pressure gauge display value Leak rate O.1 MPa, V = 4.76 m 3 ]]> 58 cm * 34 cm * 100 sections 0.126 MPa 0.06

[0046] When inspecting the sealing effect of the battery stack body, the battery stack condition can also be judged based on the position of the scale lines on the four fixings. The height of the lower pressure plate is consistent with the corresponding scale lines on the four fixings, indicating that the battery stack body has settled steadily during the sinking process, which has a good effect on correcting the deflection of the battery stack body.

[0047] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A molten carbonate fuel cell stack, characterized in that: include: A battery stack body (1) is provided with an upper pressing plate (2) and a lower pressing plate (3) on its upper and lower sides, respectively; a force sensor is provided between the upper pressing plate (2) and the battery stack body (1); the force sensor is used to measure the pressure between the upper pressing plate (2) and the battery stack body (1); A pneumatic pressure member having a slidingly matched fixing member (4) and a pressure member (5), wherein the upper pressure plate (2) is mounted on the fixing member (4), and the lower pressure plate (3) is mounted on the pressure member (5), and a sealed pressure chamber (6) is provided on the fixing member (4), and at least one end of the pressure member (5) extends into the pressure chamber (6), and the other end is mounted with a biasing member (7), and the biasing member (7) is used to apply a biasing force to the pressure member (5) toward the pressure chamber (6), and the pneumatic pressure members are provided in multiple groups, and the multiple pneumatic pressure members are symmetrically arranged around the battery stack body (1); A ventilator is connected to the pressure chamber (6) and is used to ventilate or extract air into the pressure chamber (6) to adjust the biasing force applied by the biasing member (7) to the pressure member (5) and control the pressure value measured by the force sensor to remain within a preset range.

2. The molten carbonate fuel cell stack according to claim 1, characterized in that: One end of the pneumatic pressurizing member is mounted on the edge of the upper pressing plate (2), and the other end is mounted on the edge of the lower pressing plate (3); the battery stack body (1) is arranged between multiple groups of the pneumatic pressurizing members.

3. The molten carbonate fuel cell stack according to claim 1, wherein: The biasing member (7) is an elastic member, and the elastic member is kept in a compressed state to apply a thrust to the pressure-applying member (5) toward the pressure-applying chamber (6).

4. The molten carbonate fuel cell stack according to claim 3, characterized in that: The elastic member is a pressure spring.

5. The molten carbonate fuel cell stack according to any one of claims 1 to 4, characterized in that: A thermal insulation layer (12) is provided on the top of the upper pressing plate (2).

6. The molten carbonate fuel cell stack according to any one of claims 1 to 4, characterized in that: The pneumatic pressurizing member also includes a support member, and the bottom of the fixing member (4) is fixedly mounted on the support member.

7. The molten carbonate fuel cell stack according to any one of claims 1 to 4, characterized in that: A control component is also included, and the ventilator and the force sensor are both electrically connected to the control component.

8. The molten carbonate fuel cell stack according to any one of claims 1 to 4, characterized in that: A sliding cavity is provided in the fixing member (4), one end of the sliding cavity is communicated with the pressure chamber (6), the pressure member (5) is slidably matched with the sliding cavity, and a seal is provided between the pressure member (5) and the inner wall of the sliding cavity, and the biasing member (7) is installed in the sliding cavity.

9. The molten carbonate fuel cell stack according to claim 8, characterized in that: The pressure member (5) is a sliding column, the lower pressing plate (3) is fixedly connected to the sliding column, and the fixing member (4) is provided with a clearance groove (9) for the lower pressing plate (3) to move up and down.

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