Coal gas is manufactured by the process of
destructive distillation of coal in a
retort leaving a residue of
coke. Destructive distillation of a tonne of
coal can produce 400 m3 of
coal gas, 700 kg of coke, 100 litres of
liquor ammonia and 50 litres of
coal tar.
Courtenay Place At Courtenay Place the coal was shovelled by hand into horizontal retorts made of fireclay. Very hot fires distilled the coal gas from the coal inside the retort and left the glowing coke behind. Extraction of the coke by long iron rakes required the gas-worker to face the white hot coke and pull it out towards him with the rake. To be a gas-worker a man had to be strong physically and constitutionally and this part of the work was very arduous. Only a handful of men were required to work Miramar's retorts, vertical bottles of fireclay opened at both top and bottom when required. The coal went in automatically from overhead bunkers and stayed in the retort about twelve hours by which time all the gas had been driven out of it and the residue was pure coke or carbon. With vertical retorts there was no drawing out of the hot coke by iron rake. Instead, the gas worker operated a few levers, turned a handle, and away came a torrent of incandescent coke falling into an automatic conveyor under a heavy spray of water. The gas had to undergo several processes of cleansing and purification before it was added to the gasholder. It went first to the condenser where the gas passed through water which removed most of the tar. A big rotary extractor next took the remainder of the tar and the ammonia. Finally, to remove the sulphur, which comes through from the coal in the shape of sulphuretted hydrogen, the gas was pumped through water containing quantities of red oxide of iron. The automatic conveyors and other appliances were powered by electricity generated on site by three gas engines, other equipment was powered by separate small steam engines. Activities included the manufacture of cookers, bath heaters, washing coppers, arc lamps, gas fires, circulators, toasters etc. ==Electricity==