GB958833A - Improvements in or relating to evaporators - Google Patents

Abstract

958,833. Evaporators; distilling water. RICHARDSONS WESTGARTH & CO. Ltd. Sept. 9, 1960 [Sept. 14, 1959], No. 31246/59. Heading B1B. In a multi-stage flash-type evaporator, suitable for distilling sea-water, comprising a vessel divided by internal walls 8 into a number, e.g. twenty or more, separate chambers 7 each having a tube nest 11 for heating the liquid and a flash-section 7b, at least part of each internal wall extends in a plane other than the vertical. In the horizontal evaporator shown in Figs. I and 2, the upper part 8a of each dividing wall is inclined at an angle relative to the bottom of the evaporator. In Figs. 9 and 10, the chambers are arranged one above the other and each of the internal walls 8 is contained entirely in a horizontal plane, and is provided with a reinforcing frame 12. The tube nests of the heater-sections are connected in series. The flash-sections 7b are also connected in series by apertures 9. The first heater-section is in the same chamber 7 as the last flash-section ; and the last heater-section is in the same chamber as the first flash-chamber. In operation, seawater passes successively through all the tube nests wherein it is heated by vapour flashed off in each of the flash-sections. Before the preheated brine, leaving the last tube nest, is transferred to the first flash-section, it is heated to a higher temperature by an auxiliary source of heat in a so-called heat-input section. This heat-input section may be outside the evaporator vessel, or it may be housed in the last heater-section of the evaporator vessel. The hot brine then passes successively through all the flash-sections, in each of which vaporization takes place. The vapour flashed off in each chamber condenses on the external surfaces of the tubes 11 ; and the resultant distillate is collected in a tray 17 arranged below each tube nest. The distillate may be withdrawn from each tray individually ; alternatively, the trays may be connected in series and the distillate withdrawn from a single point. In Fig. 14, each chamber 7 is divided into three sections by two reinforcing frames, the middle section 7c being used for separating any brine particles which may be entrained in the vapour.