GB1314697A - Multieffect distillation plant - Google Patents

Abstract

1314697 Multieffect distillation plant UNITED KINGDOM ATOMIC ENERGY AUTHORITY 23 Nov 1971 [23 Nov 1970] 55697/ 70 Heading B1B Liquid is distilled in a plant comprising an outer shell divided by vertical walls into horizontally juxtaposed compartments, only two of which are shown in Fig. 2, each wall supporting, on one side and in cantilever fashion, heat exchange tubes which are closed (except for small vent holes) at one end, but each tube is open at the other end which is flush with the other side of the wall. The liquid is sprayed from devices 8 so that it flows in filmform over the outside of the heat-exchange tubes, heating-medium is supplied to the interior of the heat-exchange tubes in the first compartment, and the arrangement is such that the vapour evolved from the liquid cascading down over the tubes on the left-hand wall of each compartment flows across the compartment through wire-wesh droplet-separator 7 and condenses inside the heat-exchange tubes supported on the opposite wall thereby boiling the liquid flowing down over the tubes in the adjoining compartment which is maintained at a lower pressure than the preceding compartment. The condensate runs down the tube-bores, is collected in troughs 10 and is then withdrawn from the shell through pipes 11. The vapour evolved in the last compartment flows to an external condenser. Some of the non-evaporated liquid 12, collected on the floor of each compartment, is sprayed over the heat exchange tubes in the next compartment. The heat exchange tubes may be shaped as in Fig. 2A, and may have vertical flutes in the surface of the bore and the outer periphery. The liquid to be distilled may be preheated, before it is introduced into the first compartment, by passing it through banks of heat conductive tubes which traverse the comparments in a direction counter to the liquid being distilled, so that some of the vapour condenses on the preheater tubes (Figs. 6 to 8, not shown). In the modified multieffect distillation plant shown in plan in Fig. 10, the compartments are separated by pleated sheets 52 of metal supported in parallel, vertical planes so that each sheet defines on one face an evaporator surface 52a and on its other face a condenser surface 52b. The sheets may be formed with vertical flutes. In a further modification, the pleated sheets may nest one within the other (Fig. 19, not shown).