65. Coal and Oil Required. — Water gas requires from 30 to 40 pounds of coal or coke per 1,000 cubic feet of gas made, and from 4 to 5 gallons of oil, depending on the candlepower required. Usually between 5 and 6 candlepower, is obtained from each gallon of oil used per 1,000 cubic feet. There are about 300 heat units yielded per cubic foot of uncarbureted water gas, and about 675 heat units are yielded by 24-candlepower carbureted water gas. The specific gravity of 24-candlepower water gas is about .625, air being taken as unity.
Pure uncarbureted gas has no perceptible odor, but the carbureted gas has an odor fully as strong as coal gas. This is mainly due to the hydrocarbons from the oil that is used for enriching.
66. Water-Gas Machines. — Almost all the water-gas machines now in use are modifications of the Lowe type. The Lowe type of machine consists of a generator, where the blue water gas is produced, and a superheater, or a carbureter and a superheater, where the oil is vaporized and mixed with the blue water gas. The generator is a circular steel shell, the height of which is about l1⁄2 times the diameter. It is lined with a double lining of firebrick blocks, and is provided with grate bars at the lower end and with air-tight doors at the top, where the coal is charged in, and at the bottom, where the clinkers are taken out. There are also connections for the escape of the gas and for the proper supply of steam and air. The capacity of any generator depends largely on the grate area, and may be figured at a minimum of 20,000 cubic feet of gas per square foot of grate surface per 24 hours.
ARCHER GAS
67. Archer gas is water gas made from crude petroleum by a continuous process; it derives its name from the inventor of the apparatus. The oil is pumped in a small stream into a red-hot retort, where it is quickly reduced to vapor by the heat. The oil vapor is then mixed with a current of superheated
