Gas-Engines and Producer-Gas Plants / A Practice Treatise Setting Forth the Principles of Gas-Engines and Producer Design, the Selection and Installation of an Engine, Conditions of Perfect Operation, Producer-Gas Engines and Their Possibilities, the Care of Gas-Engines and Producer-Gas Plants, with a Chapter on Volatile Hydrocarbon and Oil Engines

by Rodolphe Edgard Mathot

A gas-furnace is formed by grouping in a single mass of masonry a certain number of elements of the kind just described. It is essential that the retorts should be vertically placed, that they be made only of cast metal and not of refractory clay, and, finally, that their diameter be not much more than 10 inches, which size has been found most expedient in practice. The gas collected in the bell or in one or more of the receptacles passes into the gasometer and then into the service pipes. If 2.2 pounds of wood be distilled by burning in the furnace ⁸⁄₉ of a pound of coal of average quality or 2.2 pounds of wood (either sawdust or waste), 24.5 to 28

cubic feet of gas will be generated having a thermal value of 3,000 to 3,300 calories per cubic meter (11,904 to 13,094 B.T.U. per 35.31 cubic feet), and a residue 44 pounds of charcoal will be left.

In practice only the wood of commerce containing in the green state 20 to 40 per cent. of water, depending upon the variety, is used. Hornbeam contains the least water (18 per cent.), while elmwood and spruce contain the most (44 to 45 per cent.).

The blast apparatus of the generator being started, the gas is supplied under pressure. By reason of its permanent composition and its richness, it is an excellent substitute for street-gas in incandescent lighting, a good furnace fuel reducing agent.

Producers Using Wood Waste, Sawdust, and the Like.—If waste wood in the form of shavings, sawdust, straw, bark, and the like, should be employed, a still higher efficiency is obtained with self-reducing generators of the Riché type.

Combustion-Generators.—In combustion-generators (Fig. 88) the fuel is burnt and not distilled. The generator comprises two distinct elements. The first is the generator proper, in which the combustion takes place. Upon it is placed a hopper or fuel supply box. The Second element is the reducer, in which by an independent process the reduction of the carbonic-acid gas, the dissociation of the steam, and the transformation of the hydrocarbons takes place. The generator is provided at its base with a grate having oblique bars in tiers, which grate is furnished with a channel in which the

water for the generation of hydrogen flows. On a level with this grate, at the opposite side, is a flue communicating with the reduction column of coke. The incandescent zone of the generator should not extend above the level of the grate. Instead of passing through the layers of fresh fuel and out by way of the top, the gas generated flows directly into the reduction column where it heats the coke to incandescence. The high temperature to which the coke is subjected, coupled with the injection of air, effects useful reactions. This additional air, however, is not used if the fuel is free from all products of distillation.

Fig. 88.—Riché combustion-producer.

Experience has shown that gas of 1,000 to 1100 calories per cubic meter (3,968 to 4,365 B.T.U. per 35.31 cubic feet), which heat content is necessary to develop one horse-power per hour, can be obtained with 3.96 pounds of wood in the form of shavings and sawdust containing 30 per cent. of water. The corresponding quantity of coke consumed in the reduction column is