GB888211A - Improvements in or relating to pumps - Google Patents

Abstract

888,211. Stuffing-box substitutes. WEIR Ltd., G. & J. March 5, 1958 [Dec. 5, 1956], No. 37104/56. Class 122 (5). A fluid seal incorporated in a reciprocating or rotary pump comprises a housing 1 penetrated by the pump shaft 2 and formed with a convergent-divergent passage 4, 5, and auxiliary passages 6, 9 debouching into the convergent passage 4 and connected, respectively, to operating and auxiliary fluid sources. As applied to a boiler circulating pump, the operating fluid, which may be steam or highpressure water at saturation temperature, is fed through an inlet 7A, annular duct 7 and passage 6 of divergent or convergent-divergent form, and the auxiliary fluid, which may be cold boiler-feed water, is fed through an inlet 9A, annular passages 9 and convergent passage 8. The fluid in its transit through the passage 6 expands, loses pressure, becomes partially converted into steam (when the fluid is saturated water) and leaves the divergent passage 6 at high velocity. Cold water is thus drawn through the passages 9, 8 and caused to surround the mixed stream of water and steam issuing from the passage 6 and, as a result, all or most of the latter steam is condensed. The energy of the condensed steam is communicated to the cold water in the passage 8 and a stream of water is therefore directed at high velocity through the passages 4, 5 into the pump chamber 13 ; in this chamber the pressure of the water is greater than that of the pump discharge water thereby preventing leakage of the latter along the shaft. During starting, uncondensed steam may escape to atmosphere through a gap 10 between the convergent passages 4, 8, overflow chamber 11 and non- return valve 12.