Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ – Of inorganic materials
Reexamination Certificate
2000-02-22
2002-05-07
Cooley, Charles E. (Department: 1723)
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
Of inorganic materials
C264SDIG004, C366S340000, C210S510100, C055S523000
Reexamination Certificate
active
06383422
ABSTRACT:
BACKGROUND OF THE INVENTION
A porous member with penetrating channels for fluid flow therethrough and a method for producing the member The invention refers to a porous member of temperature-resistant material having channels extending therethrough through which a fluid (gas and/or liquid) may pass, and to a method for producing this member.
Such members are used, for example, as chemical mixers. The conventional chemical mixers consist of corrugated sheets of steel or ceramic fabrics. These abutting steel sheets or ceramic fabrics are comprised into units with crossing channels forming between the steel sheets or the fabrics. Sometimes the steel sheets are perforated so that a fluid flow passing through this chemical mixer member is homogenized, thereby mixing the fluid. For reasons of production, the individual mixer members cannot be produced with more than a certain maximum length. Thus, for producing longer mixers, a plurality of such mixer members are arranged in line. This increases the cost of the production process.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a porous member with penetrating channels through which fluid may flow, wherein the homogenization and mixing of the fluid is improved, and to provide simplified methods of producing such a member, substantially independent of the length of the porous member.
The present porous member of temperature-resistant material has an inlet surface and an outlet surface The fluid flowing through the porous member enters the porous member at the inlet surface and leaves the porous member at the outlet surface so that flow direction runs from the inlet surface towards the outlet surface. According to the invention, the porous member is provided with first channels extending under an acute angle to the flow direction. In the following, an acute angle is an angle other than 0°. Due to the porosity of the member, the channels penetrating the member are in communication so that a mixing of the fluid flowing through the porous member occurs. Since the channels form an acute angle with the flow direction, a part of the fluid flows through the channels and a part of the fluid flows in the flow direction through the porous portions, i.e., the porous walls between the channels immediately in the flow direction. Thus, the fluid (or several fluids) is mixed and homogenized so that a homogenized fluid exits from the outlet surface of the porous member.
Since the porous member is temperature-resistant, it is suited for mixing hot fluids. In doing so, due to the present structure of the member, no local overheating occurs that could damage or destroy the porous member.
Moreover, the present porous member is suited for filtering fluids.
Here, particles are deposited on the walls of the pores. Due to the temperature resistance of the member, which is made, for example, from high temperature-resistant ceramics such as zirconia oxide or silicon carbide, the member used for filtering may be cleaned by burning, whereby the residual filtered matter is combusted. This does not damage the filter. In particular, the present porous member is simultaneously suited for mixing and filtering fluids.
Depending on the shape of the porous member and the position of the inlet and outlet surfaces, the flow direction varies. For example, in a cylindrical member whose end faces are the inlet and outlet surfaces, respectively, the flow direction is straight. In a bent or otherwise shaped porous member, the center line of the member corresponds to the flow direction so that the flow direction varies in the longitudinal direction of the member.
Preferably, besides the first channels, the porous member has second channels that are also arranged under an acute angle to the flow direction and, in addition, are arranged under an angle to the first channels, i.e. an angle other than 0°. Such crossing channels that may penetrate each other at least partly, improve the homogenization and mixing of the Fluids. A further improvement may be achieved by varying the angle of the channels to the flow direction along the extension of the channels. In a cylindrical porous member with a continuous flow direction over the length of the member from the inlet to the outlet surface, the channels are wavy or zigzag-shaped, for example. Thus, a portion of the fluid flowing through the member that is sufficient to homogenize the fluid, flows through the porous portions.
The channels of the porous member are preferably arranged in rows, at least one row of first channels and a row of second channels being provided, and the channel rows being arranged alternating side-by-side and in parallel.
In a preferred embodiment, the porous member is cylindrical and the first and/or second channels extend from the inlet surface to the outlet surface of the member. Here, cylindrical means a longitudinal member with parallel end faces having the same, but an optional contour. Depending on the conditions of the device in which the porous member is used, the contour may be a curve or a polygon, for example.
Besides the usefulness of the porous member as a chemical mixer for mixing fluids and as a filter for filtering particles from fluids, the present porous member can also be used, in particular, in the combustion chamber of a pore burner.
Pore burners have a housing with an inlet and an outlet, a mixture of gas and air flowing into the pore burner through the inlet and the flue gases being exhausted from the pore burner through the outlet. Prior to ignition, the gas-air mixture flows in the flow direction of the pore burner and through a backfire means. As the backfire means, a conventional flame retention baffle or a plate with holes may be provided, for example. The backfire means prevents the gas-air mixture burning behind the backfire means, seen in the flow direction, from backfiring towards the inlet opening. The backfire means is followed by the combustion chamber in which the gas-air mixture is ignited by an ignition means and burned therein. Pore burners are characterized in that the combustion chamber accommodates a heat-resistant porous material in which the gas-air mixture is combusted. Thus, a more uniform combustion of the gas-air mixture is obtained so that within a large effective range of the pore burner, only small amounts of pollutants such as NO
x
or CO are produced during combustion. Using the present porous member in the combustion chamber of the pore burner, the emission of pollutants is reduced further. Thus, even at one thirtieth of the nominal power of the pore burner, a clean combustion is obtained. The pore burner is particularly suited for use in heating installations.
A further use of the porous member, according to the invention, is its implementation as a heat accumulator. Due to the porous structure of the member and the channels extending therethrough, the fluid flowing through the porous member is distributed homogeneously over the cross section of the member so that, when hot fluid flows through the member, the heat is received homogeneously by the porous member. When cooler fluid passes through subsequently, the heat uniformly transferred from the porous member to the fluid so that a uniform heating of the fluid occurs. Therefore, the present porous member is very well suited for use as a short- and medium-term heat accumulator.
In particular, the porous member is suited for use as a heat accumulator in regenerative radiant burners. Regenerative radiant burners serve to heat material, for example, steel ingots, by thermal radiation. Here, two radiant burners operating at intervals are employed. Each burner is provided with a porous member as the heat accumulator. Further, a blower or suction device is provided which, at intervals, either supplies the burners with a mixture of fuel and air or fresh air or exhausts the flue gases. During the first cycle, the blower directs fresh air or a mixture of gas and air through the heat exchanger of the first burner to the combustion head, where the fresh air is either mixed with fuel and ignited o
Cooley Charles E.
Deutsches Zentrum fuer Luft-und Raumfahrt e.V
Diller Ramik & Wight
Sorkin David
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