Agitating – Stationary deflector in flow-through mixing chamber
Reexamination Certificate
1999-12-20
2001-05-08
Soohoo, Tony G. (Department: 1723)
Agitating
Stationary deflector in flow-through mixing chamber
C165S184000, C428S188000, C428S192000, C428S398000
Reexamination Certificate
active
06227699
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to honeycomb articles and more particularly to honeycomb articles for providing mixing of one or more workstreams between individual channels of the honeycomb by using grooved areas to segment the individual channels and serve as mixing sites to thermally equilibrate, physically mix, or chemically react the various workstreams.
Honeycomb articles have been well documented in the patent literature. They can be used in a number of very useful applications involving their chemical, physico-chemical, physical, and mechanical properties. These include such diverse uses as purification, filtration, chemical reaction vessels, photonic band gap structures, microlens arrays, high temperature dielectric materials and even lightweight structural supports. They have been found exceptionally useful as components of catalytic converters for vehicles operating with internal combustion engines.
Because of their structure, honeycomb articles have a high surface area along with low pressure drop. This combination can be used advantageously in some applications, especially compared to applications that use packed bed columns. In these cases, the honeycomb article may not be merely an inert feature in the process, but rather may be a dynamic participant, involved either by utilizing the chemical composition of its channel walls to react with a workstream or its ability to adsorb specific materials from the workstream. These properties can be modified by temperature control or by designing the honeycomb with a specific composition such as glass, ceramic, metal, or graphite or by adjusting the porosity of the channel surfaces and walls. Further modifications can be achieved by coating the surface of the honeycomb channels with reactive, catalytic or adsorptive materials. This great amount of flexibility of design and fairly simple manufacture has made honeycomb structures commonplace in such diverse areas as fluid separations and catalytic converters.
Despite the many advantages and uses for honeycomb articles, these structures have some characteristics that are disadvantageous for certain applications. One such characteristic is that the individualized channels, even with good porosity, do not provide good mixing among workstreams in adjacent channels. For the purpose of this patent, workstreams are defined as feedstock fluids such as a gas or liquid to which either a chemical or physical change is desired. This segregated channel flow of honeycombs is not disadvantageous in certain applications where a single workstream is being processed in an isothermal environment. In other cases, however, the lack of either thermal or physical mixing can lead to inefficiencies or, in worst cases, complete failure of a desired process.
The requirement for good mixing and thermal equilibrium has led to designs that are related to honeycomb structures but allow for intermixing between channels. These structures are invariably complex and correspondingly more difficult to manufacture. To fabricate such structures by extrusion, movable dies are generally required. There is significant difficulty cleaning moveable die equipment and maintaining a continuous operation, free from downtime. Examples of such mixing articles and processes for making such articles can be found in U.S. Pat. No. 5,032,156 to Luder et al., U.S. Pat. No. 5,240,663 to Stringaro et al., U.S. Pat. No. 5,928,521 to Levec, U.S. Pat. No. 5,525,291 to St. Julien, and European Patent Application EP 0,705,962A to Toyao et al.
Therefore there exists a need to provide an economic structure that will allow facile chemical and/or thermal mixing of various workstreams. Another need is to provide a structure that allows for good mixing and intimate contact of workstreams from countercurrent flow. Still another need is to develop a structure for mixing or use as a substrate for active catalysts, adsorbers, etc. that will provide the ability to process great quantities of fluids without experiencing a great pressure drop, yet be easily manufactured.
SUMMARY OF THE INVENTION
In accordance with the invention a honeycomb article has been developed that facilitates the mixing of workstreams among the individual channels, yet still substantially preserves the partitioned flow characteristics and high surface area-to-volume ratio needed for chemical processing applications requiring high mass transfer efficiency. Moreover, the article can be made using traditional honeycomb designs as starting points for honeycomb article fabrication.
In one aspect, then, the invention includes a honeycomb article comprising a plurality of longitudinal channels extending from one end face to a second end face of the article that has a portion of the honeycomb removed by cutting at least one helical slot or groove into the honeycomb side surfaces. The helical slot or slots extend depthwise into the honeycomb from the honeycomb periphery in a direction generally transverse to the orientation of an imaginary axis joining the centers of the end faces. In general, the slots or grooves will have lengths sufficient to encircle the honeycomb at least once, and will have depths sufficient to intersect at least a majority (50% or more) of the channels making up the honeycomb at one or more points along their lengths. They may originate at points spaced away from the honeycomb end faces, or may extend continuously from the first end face to the second end face of the article, and may encircle the article one or multiple times over the course of their paths.
The honeycomb article thus described can be used in a number of applications including heat exchange, thermal mixing, physical mixing, chemical stripping, and chemical reactions of one or more workstreams entering from one face or in a countercurrent mode from both faces. In a second aspect, therefore, the invention includes a method for processing a workstream for any of a wide variety of such applications.
In summary, the method of the invention comprises first introducing a workstream into a honeycomb body comprising a first end face, a second end face, and a plurality of open-ended channels bounded by shared channel walls disposed between and connecting the first end face to the second end face. As earlier described, the body includes at least one encircling helical slot discontinuity extending inwardly through the channel walls toward an axis joining the centers of the first and second end faces. The slot discontinuity is of a depth sufficient to intersect at least a majority of the channels present in the body.
The workstream introduced into the first end face of the body is directed first into and through the first sections of the channels intersected by the helical slot discontinuity. It within these channels sections that processes such as adsorption, catalytic reaction, and/or other physical or chemical processes will be initiated.
Thereafter, the workstream is released into the helical slot discontinuity where mixing is allowed to occur. Again, mixing may serve to thermally or chemically equilibrate the workstream, or simply achieve better physical mixing thereof.
Once equilibration, mixing or the like has proceeded to a greater or lesser degree within the helical slot, the workstream is re-directed into and through second sections of the channels intersected by the slot for further interactions with the channel walls. This process may of course be repeated one or multiple times along the length of the honeycomb depending upon the number of slot intersections provided, until the workstream is finally discharged from the second end face of the honeycomb in processed form.
REFERENCES:
patent: 3887741 (1975-06-01), Dwyer
patent: 5032156 (1991-07-01), Luder et al.
patent: 5240663 (1993-08-01), Stringaro et al.
patent: 5525291 (1996-06-01), St. Julien
patent: 5633066 (1997-05-01), Lipp et al.
patent: 5928521 (1999-07-01), Levec
patent: 0705962 (1996-04-01), None
Corning Incorporated
Soohoo Tony G.
Sterre Kees van der
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