The working parts of the breaker now in use by the South Metropolitan Gas Company consist essentially of a drum provided with cutting edges projecting from it, which break up the coke against a fixed grid. The drum is cast in rings, to facilitate repairs when necessary, and the capacity of the machine can therefore be increased or diminished by varying the number of these rings. The degree of fineness of the coke when broken is determined by the regulated distance of the grid from the drum. Thus there is only one revolving member, no toothed gearing being required. Consequently the machine works with little power; the one at the Old Kent Road, which is of the full size for large works, being actually driven by a one horse power "Otto" gas-engine. Under these conditions, at a recent trial, two tons of coke were broken in half an hour, and the material delivered screened into the three classes of coke, clean breeze (worth as much as the larger coke), and dust, which at these works is used to mix with lime in the purifiers. The special advantage of the machine, besides the low power required to drive it and its simple action, lies in the small quantity of waste.
On the occasion of the trial in question, the dust obtained from two tons of coke measured only 3½ bushels, or just over a half hundredweight per ton. The following statement, prepared from the actual working of the first machine constructed, shows the practical results of its use. It should be premised that the machine is assumed to be regularly employed and driven by the full power for which it is designed, when it will easily break 8 tons of coke per hour, or 80 tons per working day:
500 feet of gas consumed by a 2 horse power gas-engine, at cost price of gas delivered s. d. in holder. 0 9 Oil and cotton waste. 0 6 Two men supplying machine with large coke, and shoveling up broken, at 4s. 6d. 9 0 Interest and wear and tear (say). 0 3 ----- Total per day. 10 6 ----- For 80 tons per day, broken at the rate of. 0 1½ Add for loss by dust and waste, 1 cwt., with price of coke at (say) 13s. 4d. per ton. 0 8 ----- Cost of breaking, per ton. 0 9½
As coke, when broken, will usually fetch from 2s. to 2s. 6d. per ton more than large, the result of using these machines is a net gain of from 1s. 3d. to 1s. 9d. per ton of coke. It is not so much the actual gain, however, that operates in favor of providing a supply of broken coke, as the certainty that by so doing a market is obtained that would not otherwise be available.
IMPROVED COKE BREAKER.
It will not be overstating the case to say that this coke breaker is by far the simplest, strongest, and most economical appliance of its kind now manufactured. That it does its work well is proved by experience; and the advantages of its construction are immediately apparent upon comparison of its simple drum and single spindle with the flying hammers or rocking jaws, or double drums with toothed gearing which characterize some other patterns of the same class of plant. It should be remarked, as already indicated, lest exception should be taken to the size of the machine chosen here for illustration, that it can be made of any size down to hand power. On the whole, however, as a few tons of broken coke might be required at short notice even in a moderate sized works, it would scarcely be advisable to depend upon too small a machine; since the regular supply of the fuel thus improved may be trusted in a short time to increase the demand.
IMPROVED COKE BREAKER.