Modern Gasworks Practice

bS 10 MODERN GASWORKS PRACTICE generator is effected by a revolving spreader. The spreader is suspended from a spur wheel mounted on a ball race and is rotated by means of bevel gearing. The illustration also shows an arrangement for automatically feeding the fuel into the generator without bringing the interior of the latter into direct commnnication with the atmosphere. Removal of Clinker The operation of clinkering the generator is the most arduous task connected with the water-gas process. With fuels of present-day quality it is usually necessary to clean out the base of the generator every four to six hours, and although mechanical devices for tlie contirmous removal of ash and clinker have been introduced, there are but few examples of their use in this country. Several methods have been tried with. the object of curtailing the labour involved, but in the main relief is best obtained by introducing a periodical “downrun” of steam. When clinker tends to hang up in the fuel-bed, or when it commences to form an arch over the cross-section of the generator, it may usually be dispersed and driven down to the grate by a succession of “down runs” carried out just prior to the cleaning time. Various attempts have been made with the object of bringing down the clinker in such a nnrner that its removal is rendered easier. The author has found that a certain amount of relief from the formation of large and hard masses which adheie to firebars and brickwork is obtained by throwing over the bars, when the generator has been cleaned, a few handfuls of ordinary grey lime. In America it is a common practice to spray with cold water the clinker adhering to the surface of the generator brickwork. This has the effect of making the clinker very friable, thus facilitating its removal. The practice would appear at first sight to have a very detrimental effect on the refractory lining, but the engineers of several American gasworks have pointed to the faet that there is no harmful influence whatever. At any rate it is essential that the water should be kept away Irom the cast-iron producer doors. (2) The Blow.—In this country the direction of the biast is always upward, no reversal being effected as in the case of the steam. The pressure of the air as delivered from the fan usually varies between 17 inch.es and 22 inches of water, but imich depends upon the type and size of the plant and the fan capacity available. It must be borne in mind, however, that the biast must under all circumstances provide an excess of air, otherwise the extent to which combustion to CO 2 takes place will be limited, witli the result that less heat is dispersed. It will be remembered, in this connection, that the partial combustion of coke to CO accounts for only one-third of the heat derived from complete combustion. In some modern forms of producer the Loomis type) the air is admitted to the top and travels in a downward direction through the fuel-bed. The primary objec-tion to the upward blow is thai an appreciable quantity of coke dust is carried forward beyond the generator. Harger suggests that the loss of fuel from this cause may amount to from 2 to 5 per cent, of the total coke used. With a downward blow, however, the cliief difficulty would seeni to be that of clinker formation and removal, so that it would appear necessary to run off the ash in the molten state.