(10) Water Gas.
Water gas is made by blowing air through a thick bed of some coal that is low in hydrocarbons until the coal becomes incandescent, the gases that are formed are allowed to escape to the atmosphere. At this point a jet of steam is blown into the incandescent bed, which is broken up into its elements, oxygen and hydrogen, by the heat of the fuel. As there is no air present the oxygen combines with the carbon of the fuel to form carbon monoxide while the hydrogen goes free. Both of these gases, carbon monoxide and hydrogen, are collected and supplied to the engine. The production of water gas is intermittent, as the steam blast cools down the fuel bed, and requires further blowing before more steam can be passed. While this gas has a lower heating value than coal gas, it is much cheaper to make and all of the coal is consumed in the process.
Water gas is high in hydrogen and is too “snappy” for gas engines; the hydrogen places a limit on the allowable compression.
For each thousand feet of water gas generated, approximately 24 pounds of water are required.
By the introduction of hydrocarbons or vaporized oil, illuminating value is given to water gas, this process is called carburetion. Carbureted gas is not usually used for power, as it is expensive, and is not proportionately high in heating value.