Seawater distillation by vertical tube evaporator - with feed and blowdown at opposite horizontal ends and water recycling

摘要

The heat exchanger has a horizontally extending array of liquid tubes within a vapour jacket. The lower ends of the tubes receive water from a manifold which receives feed sea water at one horizontal end. The water rises in the tubes when it is heated by the vapour and bubbles over at the top end into a manifold from which the water is recirculated to the lower manifold. Vapour removed from the upper manifold is compressed and supplied to the jacket of the heat exchanger. Blowdown is taken from the lower manifold at the opposite end to the feed end. By employing a wide horizontally extending array of heat exchanger tubes and attaching the feed and blowdown tubes at opposite ends a gradient of salt concentration is established in the lower manifold. This allows a higher temperature difference between the vapour and boiling point of the brine to be maintained near the inlet end of the heat exchanger. Thus a higher efficiency is achieved.