OIL FOR GAB MAKING.
The use of oil for gas manufacture was first in vented by Prof. Lowe in February, 1874, at Phoenix ville, Penn. The process was described by him as follows : "The basic principles involved were the use of a gener ator and superheater, both shells lined with fire brick. The former was provided with grate bars, air blast and steam con nections; the latter was filled with loosely piled checker brick, to give fixing surface. In the generator, non-luminous water gas was produced by the dissociation of steam in contact with carbon (in the form of anthracite coal), previously heated to incandescence by means of a forced blast of air. The superheater was brought to a suitable temperature for breaking up oil vapors by the combustion within it of the carbonic oxide formed during and by the passage of the air blast through the fuel in the generator. Oil, or oil vapors were introduced into the superheater coincident with the generation of the non-luminous water gas in the generator, and by contact with the heated fire brick surfaces the oil vapors were gasified and fixed, in the presence of the non luminous gas and during their passage together through the superheater. The process is, necessarily intermittent: first a period of blasting to bring the carbon in the generator to the proper temperature, and by complete combustion of the blast gases in the superheater to bring the checker work brick to the proper temperature for fixing the oil vapors; second, a period of gas production." This gas was called "carburetted water gas," and a high grade oil was used, mostly naphtha. There was very little demand for this grade of oil in those days, in fact the refiners had trouble in disposing of it.
When the cost of naphtha increased the manufacturers of water gas were compelled to look for a cheaper grade of oil. The crude oils of Pennsylvania having a paraffin base are very valuable for refining lubricating oil, and crude oils from other fields had to be obtained.
Improvements were made in the type of gener ator and the double superheater type came into general use in making water gas. The first water gas made
in Phoenixville required about 75 lb. of anthracite coal, and 4% gallons of oil for each 1000 cu. ft. of 23 candle power gas. In latter years with the improved double superheater type of generator, a water gas of 27.6 candle power was made from about 40 lb. of Welsh anthracite coal and 4.36 gallons of oil.
The modern process of operation may be de scribed as follows. A bed of anthracite coal is laid on the fire bars, and blown to a bright red heat by means of the air blast, furnished by a blower engine. The air in passing through the fuel not only raises its temperature, but also forms producer gas, which burns in the carbureter and the superheater, on being mixed with further supplies of air at these points. In this way the checker brick in these vessels is raised to a high temperature, while the spent gases pass out of the stack, the stack valve being open while the valve in the pipe leading to the condenser is closed. When the necessary temperature is reached, the air blast is shut off, the stack valve closed, and the gas valve opened. Steam is turned into the generator below the incandescent fuel ; this steam, coming into contact with the carbon, forms water gas which passes at high tem perature into the carbureter. Here it meets a supply of hot oil which is being sprayed over the checker ; oil gas is formed and mixes with the water gas, the mix ture going forward to the superheater and then to the condensers. When the temperature of the apparatus falls too low for the steam to combine with carbon and for the oil to be gasified by the checker work the steam and oil are turned off, the stack valve opened, the blast started, and the heating' recommences. The process is thus an intermittent one, the periods of heating up and gas making being usually about equal, ranging from five to twenty minutes each. This appa ratus performs two distinct functions: to manufacture pure water gas, and to mix this with oil gas.