40 o
MODERN GASWORKS PRACTICE
lie against the roof of the retort, and which pivot upon two axes actuated from out-side. The two hooks are coimected by a steel traversing piece which is withdrawn behind them when the appliance is being introdüced into the retort, but which •descends behind the coke when it is to be extracted. The form and size of the different parts of the machine vary in accordance with the shape and size of the retort. The time taken to insert the extractor and withdraw a charge varies from 30 to 45 seconds.
SUBSIDIARY RETORT-HOUSE MACHINES.
Düring recent years machines have been introdüced into the retort h.ouse for performing subsidiary duties such as the augering of ascension pipes, the e,liniering ■of producers, and the poking down, of fuel into the latter. Owing to th.e comparative immunity from stopped pipes in the modern retort house, however, the augering machine has disappeared, and the same may be said of the clinkerihg machine, which. has been rendered unnecessary by the introdiictioii of grates which. preclucle the formation of large masses of clinker. Indeed, the modern retort-hou.se is conspicuous for the faet that, as compared with a decade ago, arduous working conditions entail-ing considerable effort in the face of severe heat, have almost disappeared.
Clinkering Machines
The mechanical clinkering machine shown in Figs. 222 and 223 was operated 'by hydraulic, pneumatic, or steam power, and efEectively removed the heavy layer of clinker formed at the base of the fuel-bed in about one-fifth. the time required with.
manual work.* There is no particularly novel feature about its constTuction, which is on the principle of a ram, the head being designed to cut through hard masses of slag. As an instance of the saving effected it may be mentioned that at one of the larger London gasworks a single fireman was capable of dealing with three producers during his eight-hour shift; that is to say, he was deputed
Fig. 222.— Mechanical Clinkering.
to clinker retort settings yielding about half a million cubic feet of gas per diem. With the aid of the machine the man increased his daily number of fires to eight, and his gas output to 1J million cubic feet. Other advantages were the saving of fuel, owing to the shortened period for which the doors were open, and decreased Tvear and tear on the false firebars.