Mehrstufen-Entspannungsverdampfer fuer die Destillation von Seewasser od.dgl.

摘要

Flash distillation is carried out in an apparatus comprising an elongated shell 1 divided by partitions 3 into two or more stages (there are three stages, indicated by references 4, 5, 6, in the embodiment shown), each stage having a longitudinal feed-duct 7 provided with a plurality of orifices, an excess feed channel 7a, and a bundle of condenser tubes 24 extending continuously in a straight line through all the stages via sealed-holes in the partitions. The feed-ducts 7 are formed by wall 10, plate 11, and wall 8 provided with longitudinally-spaced orifices 9, wall 10 being arranged at an angle to wall 8, so that the cross-sectional area of the duct decreases in the downstream direction. The preheated feed is supplied via inlet 12 to the duct 7 of the first stage, i.e. stage 4. The successive stages are maintained at increasing vacua by steam-jet pumps (not shown). A mixture of flashed vapour and boiling liquid is ejected from the orifices 9 of ducts 7. The liquid which is not evaporated in any stage collects in channel 7a, which increases in cross-sectional area in the downstream direction. This unevaporated liquid flows through an opening in shell 1, down one side of a seal-pot 14, under wall 17, up the other side of the pot, and thence through another opening in the shell into the feed-duct 7 of the next stage. Liquid residue is withdrawn from the channel 7a of stage 6 via outlet 13. The condenser tubes 24 pass through holes in partitions 3, sealing being achieved by providing, on the higher-pressure side of the partitions, rubber sheets with holes slightly smaller than those in the partitions. The distil late, formed on tubes 24, collects on plate 20, flows into channel 20a, and passes into the channel 20a of the next stage via loop-seal 30. The distillate is withdrawn from stage 6 via outlet 31. The condenser tubes may be cooled by the liquid-to-be-distilled, which is introduced through inlet 27, and withdrawn through outlet 28. Several shells of the above type may be connected up in series.