710
MODERN GASWORKS PRACTICE
In this process the air supply from the blower is most carefully regulated, and the level of the fuel-bed should he kept constant.
A Erencli plant which has recently been introduced is illustrated in Fig. 440. The plant is more particularly suited for small works, the process consisting niainly
of obtaining a high and uniform temr perature throughout the fuel, without any appreciable production of carbon monoxide du ring the “blow.” The generator consists of an tipper and a lower portion, the latter being cylin-drical while the upper portion is tapered. It will be observed that air inlets are. provided both under the grate and at a point level with the top of the lower chamber. The blast is first admitted under the grate, by which means the lower portion of the fuel-bed is raised to incandescence. As the fuel in the upper chamber is raised in temperature slowly, no carbon monoxide appears at the generator outlet during the early period of the “ blow.” When, however, the characteristic CO flames make their appearance at this point the air blast is.divertedto the central inlet.
Fig. 440. The upper part of the fuel is in.its
turn brought to the same temperature as the bottom, without any material production of carbon monoxide, owing to the decrease by half of the height of the blown layer. As soon as the flames appear again at the throat the blast is stopped, and gasification is proceeded with. In the construction illustrated the upper valve and the air inlet cock, which constitute the only mechanical parts of the producer, are each provided with an operating lever. The two levers are in engagement with a safety lug provided on the lever of the air cock. With this lug it is impossible to open the air cock without liaving first opened the charging valve, which precludes any possibility of accident.
The Simplex Plant
The Simplex plant is in reality the development of an improvised attempt to meet, at small cost and with a minimum of delay, the abnormal demands which have recently been imposed on most gas undertakings. The plant is, of course, mainly suitable for the smaller gasworks, and as such it has met with no little success. The construction and operation of the apparatus will be readily followed from Fig. 441. It should be noticed that carburation is effected with tar, while another unusual feature is the construction of the generator of brickwork alone, i.e. without