Suction Gas

This plant does not use any gas storage system, but relies on the vacuum created in the cylinder of the engine.

A vacuum formed in the cylinder of the engine causes air to be drawn through the air cock into the vaporizer, gathering steam by passing over boiling water. The mixture is then led to a chamber below the fire-bars where excess moisture is dropped and fed into the water-seal.

Newly formed gas passes into the scrubber which is filled with coke, which is kept moist by a water spray. The gas is cleaned further by passing through wood shavings and sawdust before finding its way to the engine.

Under light load when the governer cuts out - no suction takes place, hence no fuel will be consumed. Excess gas and steam escapes into the atmosphere, by small cocks, otherwise the charge will become highly inflammable for the time being, and the temporary richness of the gas would leave its quality too poor to take a sudden increase in load. The fire would be cooled by an excess of steam.

On startup, the quality of the gas is poor until the temperature has built up (1800 F),but a hand blower can be used to assist the process. Generally fifteen minutes should be allowed before sufficient gas is produced to start the engine.

With electric ignition the spark should be retarded until the engine has attained full speed. Water consumption is approximately 3lb. per bhp. per hour. Fuel consumption is approximately 1 lb. of coal per bhp. per hour.

An engine giving 100 hp. on retorted gas from a town gas supply will only give about 80 hp. on producer gas.

The average gas composition may be: 1/4 hydrogen, 1/4 carbonic oxide and 1/2 nitrogen, depending on the fuel used.

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