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FIELD OF THE INVENTION
The present invention relates to the assembly of ceramic membrane based Solid
Oxide Fuel Cells (SOFC) for operation at high temperatures without permanently
damaging the cells. More particularly, the invention relates to a compressive sealing
device and method in which adequate sealing of the components is achieved.
BACKGROUND OF THE INVENTION
Devices such as solid oxide fuel cells (SOFCs) have huge potential for use in power
generation with much higher efficiency than the conventional methods. SOFC can
work with variety of fuels such as Hydrogen, natural gas, coal gas, LPG, bio fuels etc.
with minimal environment impact (air and noise) in addition to its operation at high
efficiency. However the commercial acceptability and wide use of such efficient
device is constraint by the complexity of its demonstration, use and reuse of the
evaluated cells particularly because of its requirement of high temperature operation.
Complexity of sealing of planner SOFCs to separate the air and fuel after housing in
the frame represents a significant barrier to their widespread demonstration, testing
and repeated use intended for power generation. In planar SOFCs, a plurality of
seals attach the cell to the interconnect and/or metal frames including sealing of the
all possible leakage points. Sealants are expected to function properly in harsh
environments at elevated temperatures. The SOFC stacks are expected to experience
multiple thermal cycles during their lifetime service in stationary or transportation
applications.

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Both rigid and compressive seals are available for assembly of ceramic cells. The most
common approach is to use rigid glass or glass-ceramic seals, the properties of which
can be tailored specifically for use with cells through variation of the glass
composition. However, these rigid seals are inherently brittle, and further, they seal
the parts permanently, and thereby preventing re-use of once dissembled parts. The
rigid seals have more stringent requirements for adherence, cracking and thermal
expansion matching. All these disadvantages limit the testing, evaluation and
subsequent reuse of the cells for various operational conditions.
US patent No. US 7,210,220 describes an apparatus and method of forming seals in
fuel cells and fuel stacks. However the method for high temperature operations of the
cells are not addressed.
US patent application Sr. No. 11/117,729 discloses a system and method of testing of
such fuel cells at the desired higher operating temperatures. Testing fixtures are
proposed in these patent applications for testing and re-testing of fuel cells without
substantial damage to the cells. In these fixtures the required sealing of the
interconnect to the metal frame and the interconnect to fuel cell both are achieved
simultaneously by applying a common compressive load to the system. These prior
art methods however, limit the extent of possible sealing for the bottom interconnect
with the metal frame.
OBJECT OF THE INVENTION
It is therefore, an object of the invention to propose a compressive sealing device and
method in which adequate sealing of the components is achieved.

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Further objects and advantages of this invention will be more apparent from the
ensuing description.
At the outset of the description which follows, it is to be understood that the ensuing
description only illustrates a particular form of this invention. However, such a
particular form is only intended as an exemplary embodiment and teaching of the
invention and not intended to be taken restrictively.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Fig. 1- shows a pictorial view of a device according to the invention
SUMMARY OF THE INVENTION
According to the invention the application of a compressive load for sealing the
interconnect and the metal frame independent of the fuel cell is made possible. Thus,
it is possible to apply high compressive load to the seal rendering it to be most
effective. This also eliminates the risk of breaking the comparatively fragile ceramic
cells by delinking them.
Further, provisions for pockets of volume around the seal or the gas distribution line
is arranged so that inert gas such as Nitrogen can be easily purged in that pocket to
create sufficient pressure, and eliminate the possibility of mix-up of the fuel and
oxidant gases during the high operation of the cell.

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The present invention discloses an effective use of the ceramic inserts to facilitate
loading of the seals with high compressive loads at high temperature. The use of high
temperature ceramic mat is also first time disclosed in this patent application which
facilitates an effective sealing at high temperature and further maintains mechanical
stability at elevated temperatures due to the special expansive properties of the
ceramic mats at high temperatures. Both the ceramic inserts and ceramic mats
disclosed herein, are capable of are electrically insulating thereby providing easy
electrical isolations of the interconnect, anode, cathodes during the production of
electricity by the cell.
The device of the invention allows application of compressive load at the bottom
interconnect plate seal placed on the metal frame.
The invention allows non-destructive testing of one or more fuel cells including
repeated use of the fuel cells for other applications.

According to the invention the application of a compressive load for sealing the
interconnect and the metal frame independent of the fuel cell is made possible. Thus,
it is possible to apply high compressive load to the seal rendering it to be most
effective. This also eliminates the risk of breaking the comparatively fragile ceramic
cells by delinking them.
Further, provisions for pockets of volume around the seal or the gas distribution line
is arranged so that inert gas such as Nitrogen can be easily purged in that pocket to
create sufficient pressure, and eliminate the possibility of mix-up of the fuel and
oxidant gases during the high operation of the cell.
The present invention discloses an effective use of the ceramic inserts to facilitate
loading of the seals with high compressive loads at high temperature. The use of high
temperature ceramic mat is also first time disclosed in this patent application which
facilitates an effective sealing at high temperature and further maintains mechanical
stability at elevated temperatures due to the special expansive properties of the
ceramic mats at high temperatures. Both the ceramic inserts and ceramic mats
disclosed herein, are capable of are electrically insulating thereby providing easy
electrical isolations of the interconnect, anode, cathodes during the production of
electricity by the cell.
The device of the invention allows application of compressive load at the bottom
interconnect plate seal placed on the metal frame.
The invention allows non-destructive testing of one or more fuel cells including
repeated use of the fuel cells for other applications.