The Vaporizing Of Paraffin for High-Speed Motors
(Electric Ignition Type)

56 VAPORIZING OF PARAFFIN. cleaned out at the same time, although not strictly necessary. However, deposit from this cause can be avoided by using condensed water, which introduces no particular difficulty in the case of engines of this size, as the necessary water amounting to approximately the same quantity as the fuel used—a grade known as gas-oil—can quite easily be got by connecting the exhaust up to a simple form of evaporator, liquifying the steam in an air-cooled condenser. Water injection, although not so absolutely necessary in engines run on the cheaper grades of semi-refined oils—gas- and solar-oil (specific gravity, 840 to 860)—is an advantage, inasmuch as it enables the full volume of the exhaust to be passed through the vaporizer jacket, and thus to heat the mixture to the maximum temperature available (600° to 800°), which is none too high for efficient vaporization of low-grade oil, even when finely pulverized ; and since the use of water injection renders it possible to run with a higher cömpression (70 to 90 Ibs.) than with a diluent of inert gas and with appreciably more power, water injection in engines of this size in which a heated vaporized mixture is supplied is a matter more of necessity than choice. Water is consequently arranged to be used in the specially designed vaporizer, illustrated by Figs. 39 and 40. for converting a 16-inch x 20-inch four-cylinder vertical producer-gas engine to run on intermediate grades of residual oils, which can be obtained at about half the cost of refined oils. The reason for converting this engine to run on oil was due to the engine only being required in service for a few hours daily, town-gas not being available, starting was thus facilitated as this occasioned no incon-