Gas and liquid contact apparatus – Contact devices – Wet baffle
Reexamination Certificate
1995-04-26
2001-07-31
Davis, Robert (Department: 1722)
Gas and liquid contact apparatus
Contact devices
Wet baffle
Reexamination Certificate
active
06267359
ABSTRACT:
The present invention relates to a method and apparatus for supporting process trays. More particularly, the present invention relates to a method and apparatus for providing a tray which can support heavy loadings with low degree of deflection and which requires fewer or no non-integral support beams.
As used throughout this document, the following definitions shall apply:
“process” shall be taken to mean, but not necessarily limited to Distillation, Flashing, Rectification, Absorption, Stripping, Evaporation, Humidification, Dehumidification, Dephlegmation, Spray Drying, Heat Transfer or any combination thereof.
“Tray”, shall be taken to be any plate type contact device used in liquid-gas or liquid-liquid mass and/or heat transfer operations. Mass and/or heat transfer process equipment using trays is based on a combination of operating principles essentially defined by three categories:
1. Mode of flow of streams: Counter-current; Co-current; and Cross-flow.
2. Gross mechanism of transfer: Differential; Integral.
3. Continuous phase: Gas (or Vapor); Liquid.
Further, a tray may be composed of one or more tray panels.
“Tray Panel”, shall be taken to mean either a single sheet metal part or one of any other number of sheet metal parts forming a tray.
“Non-integral Stiffener”, shall be taken to be any kind of stiffening not permanently affixed to the tray. This definition includes, but is not necessarily limited to, supporting beams composed of structural steel and/or fabricated beams.
“Support Beams”, shall be taken to be non-integral stiffeners including, but not necessarily limited to, structural steel shapes such as “wide flange beams”, “channels”, “angles”, or the like.
“Stiffener”, shall be taken to expressly exclude non-integral stiffeners of any sort. Further, stiffener shall be taken to be a permanently attached part intended to lend stiffness or rigidity to the tray.
“Column”, shall be taken to be any process apparatus designed to contain trays.
BACKGROUND OF THE PRESENT INVENTION
The use of trays to assist in the separation of constituents in a mixture has long been known in the art. For example, process trays sold under the trademark RIPPLE TRAY used as fractionation trays are described in Hutchinson, U.S. Pat. No.2,767,967; rod tower trays are described in Weeden et al., U.S. Pat. No. 3,414,246; and bubble cap trays are described in Guerrieri, U.S. Pat. No. 3,914,352. See also Perry & Chilton, Chemical Engineer's Handbook, 6th ed., 21-74-21-77, for a general description of perforated-plate or sieve-plate trays.
In supporting trays within the column, support beams are generally mounted in the column and trays are rested upon the support beams and the trays are fastened to the sides of the column. See, Boon et al., U.S. Pat. No. 3,649,466. In Livingston et al., U.S. Pat. No. 4,028,443 circular rings are employed to support the perforated plate.
Although the use of support beams to support trays provides sufficient support to the trays to sustain a given deflection criterion, the use of support beams suffers from both technical and economic disadvantages.
Economically, support beams are physically large, constitute large quantities of materials, are expensive and are difficult to install, especially in revamping an existing column in the field. Technically, support beams typically have the effect of becoming partitions within the columns, thus inhibiting the free movement of process gases through the column and thereby potentially causing deleterious effects upon the process itself. Still further, the use of support beams reduces the active area of the tray because the horizontal flange of the beam blocks the part of the tray which could otherwise be active for process reasons.
SUMMARY OF THE PRESENT INVENTION
The trays designed and built in accordance with the present invention constitute an improvement over all known trays employed in industry practice, whether the trays are flat or corrugated, simple perforated or valve type, with or without downcomers of any sort.
It is therefore an object of the present invention to provide new and useful improvements to the support of trays. The use of the trays of the present invention are generally self supporting, thereby enabling a reduction in the number of support beams required for a given column diameter as compared to the trays of the prior known art, or in some cases the complete elimination of such support beams.
It is a further object of the present invention to provide trays which are resistant to explosive uplift forces which are common in some process applications.
It is another object of the present invention to improve the process utility of the trays by facilitating the free movement of the process gas flow between the various sections of the columns.
It is still a further object of the present invention to provide economic advantages over the prior known art of tray support systems. Elimination and/or reduction in the number of support beams, beam seats, clips and bolting reduces the material costs of the trays, as well as the labor costs concomitant with their installation within new columns.
It is still another further object of the present invention to facilitate the revamping of existing columns. The use of support beams in revamping columns causes significant problems. Therefore, placement of support beams within a column is burdensome and time consuming. Normally beams must pass through small diameter manways. Fitting and welding beam seats and clips within the column is likewise burdensome and time consuming and has the further disadvantage of requiring welding to the pressure containing membrane.
The tray support system of the present invention overcomes all of the aforementioned disadvantages. The above and other objects and advantages shall become more apparent in light of the following description and accompanying drawings.
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patent: 2664280 (1953-12-01), Kohn
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patent: 4028443 (1977-06-01), Livingston et al.
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Davis Robert
Hedman & Costigan ,P.C.
Stone & Webster Engineering Corp.
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