Wednesday, 28 December 2016

DISTILLATION OF SEA WATER.

A. Hoehling reminds us of the impressive distillation capacity of Waratah - 5500 gallons of fresh water produced from sea water per day.

Waratah carried a water distillation apparatus manufactured by John Kirkcaldy Limited, based at Burnt Hill, originally the site of Abbey Mill of Netteswell. The principle of the apparatus required heating water to boiling point (but not too hot as to convert soluble salts and impurities into steam); collecting steam in a condenser, whereby it would be converted back into pure liquid form fit for consumption.

5500 gallons of fresh water per day seems excessive for washing, cleaning, food preparation and consumption by crew and passengers.  Prior to 1865 steam engines used seawater directly, but this was complicated by the build up of brine and scale, which had to be cleaned out at regular intervals, not to mention corrosion of boilers. With the advent of the evaporator systems, fresh water could be produced from seawater for both consumption and the feed water supply of the steam engines themselves (making up loss from evaporation) - in some extreme cases of consumption, up to 100 tons, when under full steam. The system was therefore a dual one, both for consumption and for the twin quadruple expansion engines. The evaporator consisted of a drum filled with a circuit of coiled pipes which passed to a distilling condenser. A further advantage of this system, utilising seawater directly, prevented contamination from water used in the boiler circuit of the steam engine.   









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