CN110729498B

CN110729498B - A flat-type solid oxide fuel cell sealing structure

Info

Publication number: CN110729498B
Application number: CN201911004983.5A
Authority: CN
Inventors: 申双林; 陈亚平; 万兴文
Original assignee: China University of Mining and Technology Beijing CUMTB
Current assignee: China University of Mining and Technology Beijing CUMTB
Priority date: 2019-10-22
Filing date: 2019-10-22
Publication date: 2021-07-23
Anticipated expiration: 2039-10-22
Also published as: CN110729498A

Abstract

The invention discloses a sealing structure of a flat-plate solid oxide fuel cell, comprising a shell filled with nitrogen and provided with a battery stack. The battery stack comprises two parallel current collecting plates, which are clamped between the two current collecting plates. There is an electrode group, the side surface of the collector plate close to the electrode group is provided with a swirling guide groove, the middle part of the collector plate is provided with an air inlet which is connected to the swirling guide groove, and the middle part of the collector plate is connected with the swirling guide groove. The air inlet through the air inlet and the air outlet through the swirling diversion groove are respectively opened on the circumferential end face of the collector plate; the flow of nitrogen on the outside of the fuel cell stack keeps the stack at the outside The pressure is slightly higher than the internal micro-positive pressure state, which prevents the gas inside the fuel cell stack from leaking out under the pressure difference, reduces the fuel gas concentration diffusion leakage, eliminates the pressure difference leakage, does not need to add any sealing material, reduces the The manufacturing cost greatly improves the stability and service life of the fuel cell.

Description

Sealing structure of flat plate type solid oxide fuel cell

Technical Field

The invention relates to the field of fuel cells, in particular to a sealing structure of a flat-plate type solid oxide fuel cell.

Background

The fuel cell is known as the clean and high-efficiency power generation technology of the 21 st century, and in recent years, although the research of a flat Solid Oxide Fuel Cell (SOFC) has made some progress, the high-temperature sealing problem is still one of the main technical difficulties restricting the development of the flat SOFC. At present, the commonly adopted sealing methods of the fuel cell are mainly three, namely glass and glass ceramic-based sealing, high-temperature metal sealing and mica-based sealing.

Glass and glass-ceramic based seals are most common, but in use, both the glass transition temperature of the glass and the coefficient of thermal expansion of the glass need to be considered. The requirement of air tightness can be met only by balancing the full flow of glass and glass ceramic and ensuring that the sufficient rigidity does not exceed the allowable stress of the glass and glass ceramic and ensuring that the glass and glass ceramic are matched with the thermal expansion of the fuel cell assembly in the using process; the glass ceramic-based sealing material is obtained by pre-designing the components and controlling the crystallization of glass, and the quantity and the microscopic characteristics of crystalline phases are controlled to achieve the required performance. When glass-ceramics are used as sealing materials, the surface must be wetted before crystallization to allow bonding or sintering to full density. If crystallization occurs before sufficient wetting or sintering, poor adhesion or porosity can result. On the contrary, insufficient crystallization leads to deterioration of mechanical properties. As research progresses, there remain several problematic issues with the use of glass and glass ceramic based seals. Glass ceramics are brittle and easily crack below the transition temperature. Typically, both glass and glass-ceramics contain the alkali element chromium, which reacts with other components of the fuel cell to increase the volatility of the chromium, which poisons the cathode and results in a decrease in SOFC performance. The long term stability of glass-ceramics in the fuel cell operating environment is also a problem that needs to be verified. This is mainly due to the fact that glass is a thermodynamically unstable phase that may undergo a transition to a more stable crystalline phase if exposed to high temperatures for a long period of time, thereby possibly altering some initial designs and bringing some unknown effects

In addition, there have been studies on the use of mica-based seals in high-temperature metal seal boxes, which are relatively brittle and can withstand certain mechanical stresses, but which are currently relatively expensive and difficult to commercialize. Mica-based seals are of great interest because they do not require a particularly precise thermal match and do not closely connect adjacent components, but the materials used, such as muscovite, contain potassium, which can cause reaction with components of the fuel cell assembly during long-term use, and the economic zone of sealing performance is at 700 ℃ and 850 ℃, which makes it difficult for high performance fuel cells to achieve high performance sealing requirements.

Disclosure of Invention

In view of the above technical deficiencies, an object of the present invention is to provide a flat solid oxide fuel cell sealing structure, which utilizes the flow of nitrogen around the fuel cell stack to make the external pressure of the fuel cell stack greater than the internal pressure, so as to form a micro-positive pressure state, thereby preventing the internal gas of the fuel cell stack from leaking outwards under the driving of differential pressure, reducing the concentration diffusion leakage of reactant gas, eliminating the differential pressure leakage, realizing sealing, and reducing the manufacturing cost without adding any sealing material, thereby greatly improving the stability and the service life of the fuel cell.

In order to solve the technical problems, the invention adopts the following technical scheme:

the invention provides a flat plate type solid oxide fuel cell sealing structure which comprises a shell, wherein the shell is filled with nitrogen and forms micro positive pressure airflow flowing circulation in the shell through the nitrogen, a cell stack is arranged in the shell and comprises an upper current collecting plate and a lower current collecting plate which are arranged in parallel, an electrode group is clamped between the two current collecting plates, a side surface, close to the electrode group, of each current collecting plate is provided with a rotary flow guide groove, the middle part of each current collecting plate is provided with an air inlet communicated with the rotary flow guide groove, the circumferential end surface of each current collecting plate is respectively provided with an air inlet communicated with the air inlet and an air outlet communicated with the rotary flow guide groove, and the air inlet and the air outlet are respectively provided with an air inlet joint and an air outlet joint.

Preferably, the midpoint of the connecting line of the air inlet and the air outlet coincides with the center of the collector plate.

Preferably, the shape of the swirl channels includes rectangular, circular and spiral.

Preferably, the swirl diversion trench divides the collector plate into an outer wall and a plurality of circles of inner baffle plates, and the width of the outer wall is the same as that of the inner baffle plates.

The device starts with two main driving forces causing fuel cell leakage, namely concentration driving and differential pressure driving; in the cell stack, a mode of feeding gas from the center of the electrode group, uniformly flowing to the periphery through the convolution diversion trench and exhausting gas from the edge is adopted, in the flowing process of the gas, the reaction gas participates in the electrochemical reaction, the concentration of the reaction gas is gradually reduced from the center to the periphery, the concentration of reactants at the edge of the electrode group reaches the lowest, and the internal gas is prevented from leaking to the outside due to concentration driving; outside the fuel cell, the pressure outside the fuel cell is higher than the pressure inside the fuel cell in a nitrogen introducing mode, and the external pressure is higher than the internal pressure to form a pressure difference, so that the gas inside the cell stack is prevented from leaking outwards; the device does not need to use sealing materials during manufacturing, reduces manufacturing difficulty and cost, improves battery operation stability and prolongs the service life of the battery.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a sealing structure (exploded view) of a flat solid oxide fuel cell according to an embodiment of the present invention;

FIG. 2 is a top view of the underside collector plate (fuel side) provided by an embodiment of the present invention;

FIG. 3 is a structural schematic view (side view) of a sealing structure of a flat solid oxide fuel cell according to an embodiment of the present invention;

fig. 4 is a schematic structural view (side view) of a fuel cell ribbon:

fig. 5 is a cross-sectional view of section B-B of fig. 4.

Description of reference numerals:

1. the device comprises a collector plate, 2, an electrode group, 3, an air inlet, 4, an air outlet, 5, an air inlet, 6, a rotary diversion trench, 7, an outer wall, 8, an inner partition plate, 9 and a shell.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1 to 5, a flat plate type solid oxide fuel cell sealing structure comprises a casing 9 filled with nitrogen gas and forming micro positive pressure gas flow circulation in the casing through the nitrogen gas, a cell stack is arranged in the casing 9, the cell stack comprises two current collecting plates 1 which are parallel to each other and arranged at a 90-degree cross included angle, an electrode group 2 is clamped between the two current collecting plates 1, a convoluted flow guide groove 6 is formed in one side surface of the current collecting plate 1 close to the electrode group 2, an air inlet 5 communicated with the convoluted flow guide groove 6 is formed in the middle of the current collecting plate 1, an air inlet 3 communicated with the air inlet 5 and an air outlet 4 communicated with the convoluted flow guide groove 6 are respectively formed in the circumferential end surface of the current collecting plate 1, and an air inlet joint and an air outlet joint are respectively formed on the air inlet 3 and the air outlet 4.

The midpoint of the connecting line of the air inlet 3 and the air outlet 4 coincides with the center of the collector plate 1.

The shape of the swirl guide groove 6 includes a rectangle, a circle, and a spiral.

The collecting plate 1 is divided into an outer wall 7 and a plurality of circles of inner partition plates 8 by the convolute diversion trenches 6, and the width of the outer wall 7 is the same as that of the inner partition plates 8.

When in use, N with a certain flow is introduced into the shell 9₂Gas sealing the stack with N₂The micro-positive pressure state generated by the circulation flow around the fuel cell causes the outer side pressure of the cell stack to be larger than the inner pressure, and the pressure difference prevents the fuel gas and the oxygen from leaking outwards, thereby achieving the purpose of sealing.

The device starts with two main driving forces causing fuel cell leakage, namely concentration driving and differential pressure driving; the gas inlet 3 is externally connected with reaction gas through a pipeline, the reaction gas flows into the middle of the rotary flow guide groove 6 through the gas inlet 5, the gas outlet 4 is connected with the outside of the shell 9 through a pipeline, the reaction gas in the cell stack flows from the center of the electrode group 2, flows uniformly to the periphery through the rotary flow guide groove 6 and exhausts from the edge, in the flowing process of the gas, the reaction gas participates in electrochemical reaction, the concentration of the reaction gas is gradually reduced from the center to the periphery, the concentration of reactants at the edge of the electrode group 2 reaches the lowest, and the internal gas is prevented from leaking to the outside due to concentration difference driving; in the outer part of the fuel cell, namely the shell 9, the external pressure of the fuel cell is higher than the internal pressure in a nitrogen gas introducing mode, and the external pressure is higher than the internal pressure to form a pressure difference, so that the gas in the cell stack is prevented from leaking outwards; the device does not need to use sealing materials during manufacturing, reduces manufacturing difficulty and cost, improves battery operation stability and prolongs the service life of the battery.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A sealing structure of a flat-plate solid oxide fuel cell, characterized in that it comprises a casing (9) filled with nitrogen and forming a micro-positive pressure air flow circulation inside through the nitrogen, and the casing (9) is provided with a casing (9). A battery stack, the battery stack includes two upper and lower current collector plates (1) parallel to each other, an electrode group (2) is clamped between the two current collector plates (1), and the current collector plate (1) is close to the electrode group (2) A swirling guide groove (6) is opened on one side of the collecting plate (1), an air inlet (5) connected to the swirling guide groove (6) is arranged in the middle of the collecting plate (1), and the circumferential direction of the collecting plate (1) is An air inlet (3) communicated with the air inlet (5) and an air outlet (4) communicated with the swirl guide groove (6) are respectively opened on the end face. The air inlet (3) is provided with an air inlet connector and an air outlet (4) is provided with an air outlet; the midpoint of the line connecting the air inlet (3) and the air outlet (4) coincides with the center of the collector plate (1); the shape of the swirl guide groove (6) includes rectangular, circular and Spiral; the swirling guide groove (6) divides the collector plate (1) into an outer wall (7) and several circles of inner partitions (8), and the outer wall (7) and the inner partition (8) have the same width.