GB547455A - Improvements in method and apparatus for pumping volatile liquids - Google Patents

Abstract

547,455. Pumping volatile liquids ; plunger packing. LINDE AIR PRODUCTS CO. June 16, 1941, Nos. 7588, 7589. 7590. 7591, 7592 and 7593. Convention date, June 15, 1940. [Class 102 (i)] [Also in Group XXVI] In apparatus for pumping, against a relatively high pressure, liquid-oxygen or like volatile liquid having a boiling point substantially below 273 degrees absolute at atmospheric pressure, the liquid is initially sub-cooled, introduced into a high-pressure reciprocating pump 14 having a narrow clearance space between the plunger 16 and the pump cylinder 15 sufficient to avoid subjecting the liquid to a pressure substantially in excess of the discharge pressure of the liquid and then displaced from the pump by relatively rapid counter-movement of the liquid and plunger whereby the liquid cools the plunger sufficiently to prevent vaporization of liquid introduced into the pump. The sub-cooling may be obtained by (i) using a storage chamber 10 elevated to a height sufficient to provide a gravity-produced pressure, (ii) expanding a portion of the liquid by throttling and heat-exchanging means while in' heat-conducting relation with the reciprocating pump supply conduit 11, 13 or (iii) using a booster pump 12 to compress the liquid without increasing its temperature. The reciprocating pump 14 is supported in an insulating casing 26, whilst its discharge valve 17 is arranged above the inlet valve 18 to allowany collected gas to be swept out of the cylinder 15, and is connected to a vaporizer 20 for supplying a high-pressure gas distributing system. The plunger 16 is reciprocated by a straight-line linkage mechanism 28 . . 32 coupled to the connecting rod 33 of a pulley 36 driven by an electric motor 38. In a modified form, two out-of-phase parallel reciprocating pumps are similarly operated from a single electric motor. The cylinder 15 may comprise three cylindrical elements 80, 81, 82, Fig. 5, and a block 84 all screwed together, the block 84 carrying a safety disc 91 which ruptures at a predetermined high pressure. The discharge conduit 99 may encircle the cylindrical elements 81, 82 to form a heat screen, whilst the element 81 may be fitted with a bushing 100 of bonded graphite, which excludes heat and lubricates the plunger, and which is secured in position by a metal spacing collar 101 and a sealing washer 102, the collar 101 being bored radially opposite the discharge outlet 95. The element 82 is closed by glands 103, 104 which hold in position a number of relatively hard packing rings 89 composed of shreds of bearing metal and flake graphite. These hard' packing rings may be arranged in groups at the ends of the packing sleeve on either side of one or more soft-cored rings composed of fibrous asbestos inside a cover of woven asbestos. Groups of soft cored rings may be separated by pairs of tapered metal rings forming reservoirs for flake graphite.