PLASTIC HEAT EXCHANGER WITH ANTI-BUOYANCY MEANS

1,240,141. Heating and cooling liquids in bulk; heat exchanger tubes. NORTH AMERICAN ROCKWELL CORP. 25 June, 1968 [26 June, 1967], No. 30301/68. Heading F4S. Heat exchanger tube banks, e.g. 70, 72, 74, Fig. 4, extending between headers 44, 60, Fig. 1, and carrying a fluid under pressure, are each made from two sheets of plastics film material (such as P.V.C.) seamed together at intervals (e.g. along spaced-apart parallel lines 88, 90, 92, Fig. 3) to form the tubes 56 of the bank, each tube having anti-buoyancy means therein adapted in use when the tube banks are immersed in a fluid in a tank 16, to provide neutral buoyancy. The anti-buoyancy means may comprise wires 76, 78, 80 inserted in selected tubes of each bank and connected at their ends to the headers. The tank shown includes inlet and outlet chambers 32, 62 respectively for the tube-side fluid, and the headers 44, 60 which may be of flexible material and in the form of multiple header units (Fig. 2) interconnect these chambers with the tubes. Fluid flow through the tubes may be regulated by valves 52 in the header 44. In use, raw sea water on its way to a distillation plant is preheated as it gravitates through the tank 16 by fresh water passing out of the plant.