# US 4,391,675 A · Sieve plates and distillation columns > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,391,675 A - Document ID: US4391675A - Status: Granted - Kind: A - Application number: 06/337,324 - Filed: 1982-01-05 - Granted: 1983-07-05 - Earliest claimed: 1981-01-08 - Assignees: BP Chemicals Limited - Inventors: Malcolm Lynn; Peter E. May - Web page: https://patentgrep.com/patent/US4391675A ## CPC - B01D 3/22: with horizontal sieve plates or grids; Construction of sieve plates or grids - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) ## Abstract A sieve plate of polymeric material for use in a distillation column, characterized in that said plate comprises: (a) a circular base portion provided with (i) a central axial aperture adapted to receive a shaft, (ii) an additional aperture capable of receiving a tubular member, and (iii) a plurality of perforations such that the perforations represent in total a free area of between 3 and 20%, the perforations having a uniform average diameter between 0.6 and 4.0 mm, (b) a flexible, flared-lip portion around the circumference of the base portion capable of sealing contact with the inner walls of a column, and (c) means for retaining the sieve plate on a shaft. ## Claims ### Claim 1 A sieve plate of polymeric material for use in a distillation column, characterised in that said plate comprises: (a) a circular base portion provided with (i) a central axial aperture adapted to receive a shaft, (ii) an additional aperture capable of receiving a tubular member, and (iii) a plurality of perforations such that the perforations represent in total a free area of between 3 and 20%, the perforations having a uniform average diameter between 0.6 and 4.0 mm, (b) a flexible, flared-lip portion around the circumference of the base portion providing sealing contact with the inner walls of a column and providing a reservoir for downcoming liquid, and (c) means for retaining the sieve plate on a shaft. ### Claim 2 (depends on 1) A sieve plate according to claim 1 wherein the perforations are distributed in such a manner that a small segment of the base portion is left unperforated. ### Claim 3 A distillation column which is provided with a plurality of spaced sieve plates, characterised in that the sieve plates are of polymeric material and are mounted on a central shaft coaxial with the column, said sieve plate comprising: (a) a circular base portion provided with (i) a central axial aperture adapted to receive the shaft, (ii) an additional aperture spaced from the central aperture and capable of receiving a tubular member acting as a weir and a downcomer, and (iii) a plurality of perforations such that the perforations represent in total a free area of between 3 and 20%, the perforations having a uniform average diameter between 0.6 and 4.0 mm, (b) a flexible, flared-lip portion around the circumference of the base providing sealing contact with the inner walls of the column and providing a reservoir for downcoming liquid, and (c) means for retaining the plate on the shaft. ### Claim 4 (depends on 3) A distillation column according to claim 3 wherein the tubular member is constructed of a different material to that of which the sieve plate is made. ### Claim 5 (depends on 3, 4) A distillation column according to claim 3 or 4 wherein the means for retaining the sieve-plate on the shaft is a combination of a coaxial boss with a pair of opposing holes on the plates and correspondingly aligned holes on the shaft enabling a cross-pin or lock-pin to be inserted through the holes in the boss and the shaft to retain the plate in position. ### Claim 6 (depends on 5) A distillation column according to claim 5 wherein the boss is on the side of the plate opposite that bearing the lip portion. ### Claim 7 (depends on 3, 4) A distillation column according to claim 3 or 4 wherein the shaft and the axial aperture in the plate have between them a combination of an annular slot and a flange which mate to form the retaining means. ### Claim 8 (depends on 7) A distillation column according to claim 7 wherein the flange is either an O-ring or an integral projection on the appropriate shaft or plate aperture. ### Claim 9 (depends on 3, 4) A distillation column according to claims 3 or 4 wherein the shaft is provided along its length with a series of means for the purpose of mounting several sieve plates on the shaft said means being adapted to adjust the spacing between the plates and/or the weir height and downcomer length. ### Claim 10 (depends on 3) A distillation column as claimed in claim 3, wherein adjacent sieve plates are arranged so that the liquid descending from the plate immediately above is directed to an unperforated area of the plate below.