THE COMPLETE GASIFICATION OF COAL
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Air and steam are blown alternately into the generator. During the air blow
the gas valve is closed and the products of combustion pass through ports into the
anntilar space surroimding the retort, the heat generated being transmitted through the chequer brickwork therein to the retort and the waste gases passing through
the snift valve and away into the atmosphere. When the generator portion of the
plant is blown up to a sufficient heat the air is shut off and steam is turned on. The water gas so gener-ated passes up through the vertical retort, and the heat of the water gas, together with that evolved around the retort during the blow, causes the coal descending the retort to be subjected to a low-temperature carbonization.
A supply of secondary air is admitted to the annular space surrounding the coal retort to bum the combustibles in the blow gases.
Doherty’s Psocess
The plant employed for the complete gasifica-tion of coal by H. L. Doherty 1 dillers in many re-spects from those described above. A vertical section of the generating portion of the plant is shown in Kg. 468. The horizontal section of the fuel chamber and one regenerator is shown. in Fig. 469.
The coal is fed intermittently through the charging opening at the top of the fuel chamber, and coke may be intermittently discharged through an extracting chamber at the base of the generator.
Gas is produced from the fuel in two distinct operations—namely, a biowing or heating operation and a gas-making operation. In the biowing operation, air is blown through the fuel column and passes into the base of one of a pair of regenerators ; the products flow up through the regenerator, and then pass through a horizontal flue into the mid-portion of the fuel column. The biast exhaust gases pass out of the fuel column at a high, temperature, and flow through one of the flues into one of the
Fig. 467.—Bboadhbad’s Plant.
heat regenerators, where the heat is absorbed from the gases and the gases pass out comparatively cool through outlet pipes. When the heat of the exhaust gases has built-up the temperature of one regenerator, the incoming air from the blower is reversed by valves to admit the air through the heated regenerator, so as to exhaust the air through the regenerator previously used for preheating the air. The fuel
1 E.P. 132,488/20.