Engineering Wonders of the World
Volume I

THE DEVELOPMENT OF THE GAS ENGINE. 225 you will notice that the cylinder is enclosed in a water Cooling- Large Pistons. jacket, and also that the piston itself is full of water. In very large engines it is necessary to provide water circulation in the pistons, and even in the valves, as these parts contain large exhaust so much metal that, but for artificial cooling, they would soon get so hot as to interfere with proper lubrication and cause preignition of the charge. This is especially true of a closed- in cylinder, heated at both ends, as in the case which we have before us. Jacketing of . moving parts requires the use of water pipes flexibly jointed after the manner of those which convey oil under pressure to the crank pins and crossheads of large steam engines. Fig. 14 discloses a hollow piston rod encircling a smaller internal pipe. The cool water is forced in through the small pipe, and, after travelling through the piston, escapes by the annular space between the pipe and the rod. It fell to the writer to make a test, several years ago, of the first engine ever driven by blast-furnace gas, and lie said at the time that there was a regular Niagara of energy going to waste in the shape of unused gas. It has been estimated that the gas generated by the coke fed into a blast furnace is sufficient to operate the blowing engines, other machinery, and the stoves for heating the blast, and leave 1,500 h.p. over. At this moment, probably more than 500,000 h.p. is being developed in Germany by the gas engines using blast gases. Assum- ing half of the blast gas produced in Great Britain to be employed on heating stoves, there must remain some 2,000,000 h.p. con- tinually available for lighting towns electrically, driving mills, working tramways, pumping water or sewage, and serving the general power purposes at iron and steel works for which coal is now consumed. The day will doubtless come when we shall make profitable use of <'.«> I5 Fig. 17.-SKETCH TO SHOW CYCLE OF OPERATIONS WHEREBY A BLAST FURNACE AND A GAS ENGINE AID EACH OTHER. this valuable by-product of one of our greatest industries. Until we do, we have no right to grumble over the too rapid exhaustion of our coal supplies. The blast furnace is really an ideal “ producer/1 and every plant which makes use of its gas for power purposes furnishes a beautiful An example of a continuous cycle Interesting r J Cycle of ot operations mutually assist- operations, ing one another. We have had a sketch (Fig. 17) drawn to impress the nature of the cycle on the mind of the reader. Begin- ning at the furnace, f, where the gas conies into being, we follow it through the gas main to c (the scrubbers), and then through fjf (a series of cleaning fans, described on a previous page) to e (the engine), where it does the work necessary to drive the blowing tub, T. The tub pumps the blast air through the air main, b, to s s, the stoves in which it is heated before delivery to the blast furnace. The gas indirectly supplies the air, which contributes in turn to the formation of gas. So there is a fair give-and-take all round. The writer hopes that the above account of the growth of the gas engine from a small affair of a few horse-power to the monster of Wealth in Blast- Furnace Gas.