DE10235485A1 - High-temperature ceramic matrix composite ring seal for oxygen generator, partial oxidation of hydrocarbons - Google Patents

Abstract

A high-temperature (to 1000C) gas seal (6) is positioned between two ceramic components (1, 3) or a ceramic and a metal component. The seal is esp. fabricated from a material which is a compound material with a ceramic matrix with a self-sealing formed ring. The ceramic matrix is made of e.g. pure ceramic material, glass ceramic, pure glass, or a mixture of these.

Description

The invention relates to a gas-tight Connection between a first ceramic and a second ceramic and / or metallic part of the apparatus.

For systems operating in a high temperature range, for example in the range up to 1000 ° C, can be operated for certain Plant parts ceramic materials may be advantageous. For example for plants for oxygen production or partial oxidation of hydrocarbons occasionally ceramic high temperature tube bundle heat exchangers or reactors and Membrane tube bundle modules proposed from ceramic. Problematic when using Ceramic materials in such plants, however, is the manufacture of a gastight connection between the ceramic material and a connecting body. At the Ceramic pipes are used e.g. on a gas-tight Connection between the ceramic tubes and the metallic ones or ceramic tube sheets at high pressures and temperatures of up to 1000 ° C on.

So far, in such cases Gas tightness usually through a cohesive Connection by soldering manufactured. A ceramic / ceramic solder joint or ceramic / metal is feasible, but requires a complex one Process, since a previous metallization of the ceramic surfaces or the use of a reactive solder is necessary. Besides, is such a solder joint is not solvable. A solder joint between ceramic and metal is particularly at operating temperatures up to 1000 ° C problematic because between the melting temperatures of solder and metallic materials there is only a slight difference. It is coming too much tension within the solder joint when the temperature changes due to different thermal expansion of ceramic, solder and metal. At different pipe temperatures when using several pipes there is also strong tension in the pipes in the axial direction Direction, with already low tensile stresses to break the ceramic Lead pipes can. Independently a tube bundle jacket is required be provided with an axial expansion compensator.

A similar connection is also achieved when the metallic solders are replaced by melting ceramic mixtures ( U.S. Patent 5,725,218 ). Metallization is not required for these connections. However, the remaining disadvantages cannot be eliminated.

From the EP 1 067 320 A2 a positive releasable connection with self-sealing metallic form rings is known. Here, the principle known for shaft sealing is used, which is based on metallic shaped rings which, coaxially to the pipe axis, clamp on the inner diameter on the pipe surface and on the outer diameter in a recess in the connecting body. The form rings are hollow and, after assembly, their open side points in the direction of the higher pressure, which increases the clamping effect under operating conditions and, provided that there is elastic stress, the form rings adapt to the expansion differences in the radial direction and thus ensure a temperature and pressure swing resistant seal , No major stresses can occur in the pipes in the axial direction due to different thermal expansion. The disadvantage, however, is that the shaped rings are made of metal. As a result of the low elasticity of the high-temperature steels that can be used, only slight differences in elongation can be compensated elastically without leaks or damaging deformations of the molded rings occurring. Furthermore, the creep behavior of the metallic materials will have a disruptive effect at operating temperatures of up to 1000 ° C, which in permanent operation will lead to permanent deformation until the form rings are destroyed.

The invention has for its object a To provide connection of the type mentioned, which also at Pressure differences and high temperatures as well as strong temperature fluctuations gas-tight and detachable is.

This object is achieved according to the invention solved, that the connection of a composite material with a ceramic matrix is formed. The basic idea of the invention is therefore instead of metallic Materials for the gas-tight connection of composite materials with ceramic matrix, known as Ceramic Matrix Composite (CMC). As a result the ceramic matrix causes undesirable creep in such materials only at much higher ones Temperatures, generally well above 1000 ° C. As a filler Composite components used have high temperature resistance, high elasticity and high tensile strength. These positive properties are attributed to the transfer ceramic matrix, so that a suitable CMC material compared to metallic materials a comparatively high elasticity and high creep resistance has.

The ceramic matrix can be made from pure Ceramics or from glass ceramics or from pure glass or also from Mixtures of these types of materials exist. An example of one CMC material that can be used is mica / perovskite oxide ceramic.

The gas-tight connection according to the invention is preferably used in pipes. In this case, the first apparatus part consists of a ceramic tube and the second apparatus part of a ceramic or metallic tube sheet. In addition, the gas-tight connection expediently has at least one self-sealing shaped ring. The molded ring, which is made of a composite material with a ceramic matrix, ensures a gas-tight and detachable connection between the ceramic tube and the ceramic or metallic tube sheet.

The invention is suitable for all conceivable apparatus parts, where there is a gastight and detachable connection between one first ceramic apparatus part and a second ceramic and / or metallic apparatus part arrives. The invention can be advantageous especially in the case of partial oxidation synthesis gas reactors or oxygen separators be used. But also an application in fuel cells is conceivable.

The invention is intended to be described below an embodiment shown schematically in the figure are explained in more detail:

In the figure is a high temperature seal for ceramic Tubes shown.

The ceramic tube 1 is through the opening 2 of the ceramic or metallic connecting body 3 (in the present case tube sheet) performed. The individual sealing elements, which are preferably all made of CMC, are located in an annular recess 4 of the connecting body 3 coaxial to the axis of the ceramic tube 1 , The base ring belongs to the sealing elements 5 on which the form ring is located 6 and on this the spacer ring 7 located. Analogously, there are two further form rings 6 with a spacer in between 7 arranged. The head ring forms the end 8th , By means of the spring ring, which preferably also consists of CMC 9 all sealing elements are fixed in the axial direction. The form rings 6 point with their open side upwards in the direction of the higher gas pressure (in the example: gas pressure above the tube sheet or in the ceramic tubes higher than below the tube sheet). As a result, the radial boundary surfaces of the form rings 6 against the inner boundary (ceramic tube 1 ) and outer boundary (connecting body 3 ) pressed elastically, which creates a permanent seal. The device allows axial movement of the ceramic tube 1 relative to the connector body 3 to.

At least one shaped ring comes in the device 6 , preferably three form rings 6 to use. With only one form ring 6 there are no spacer rings 7 ,

The shape rings are also designed differently than in 1 shown possible. However, it is common to all shaped rings that they are hollow and open on one side and that the effect described above is achieved.

Claims (4)

Gas-tight connection ( 6 ) between a first ceramic ( 1 ) and a second ceramic and / or metallic part of the apparatus ( 3 ), Characterized in that the compound ( 6 ) is formed from a composite material with a ceramic matrix. Gas-tight connection according to claim 1, characterized in that the first apparatus part ( 1 ) from a ceramic tube and the second part of the apparatus ( 3 ) consists of a ceramic or metallic tube sheet. Gas-tight connection according to claim 1 or 2, characterized in that the connection ( 6 ) has at least one self-sealing ring. Gas-tight connection according to one of claims 1 to 3, characterized in that that the ceramic matrix of pure ceramic, glass ceramic, pure Glass or mixtures of these materials.