Modern Gasworks Practice

174 MODERN GASWORKS PRACTICE The outside producers were, of course, fed with cold coke and were subjected to steaming, The free space in the retort was adjustable at will byregulation of the coal feed ; and the gas was taken off to a dry main. The approximate time occupied by the coal in travelling from the top to the base of the retort was twenty-four hours. THE HOLMES-WINSTANLEY SEMI-CONTINUOUS SYSTEM This system consists of retorts rectangular in section, set vertically, and grouped in pairs. A coal hopper is provided at the upper end of each retort capable of con-taining twenty-four hours’ supply of coal, the latter being in direct communication with the retort, no intermediate valve or feeding device being provided. The base of the retort consists of a Casting set at an angle of 45° and terminating in a mouthpiece, enabling the coke to be discharged at the side of the structure and, when required, direct into the producer. Fig. 93 shows a cross-section of the setting through, the retorts, and Fig. 94 gives a general outline of an installation of ten retorts. Each retort is designed for a throughput of 3 to 3| tons of coal per twenty-four hours. The coal is supplied to the hoppers by means of a travelling bogie fitted. with. a bottom discharging door. A feeding door is provided in the top of the hopper which engages automatically with the travelling bogie on the latter being brought into position over it. Thus coal is admitted without loss of gas (see Fig. 95). It will be seen that the contents of the retort are under constant pressure from the column of coal in the hopper, the “ free space ” being practically confined to a small pocket formed at the gas outlet. The coal in the hoppers may be replenished at convenient intervals, or the hoppers may be filled every twenty-four hours. The coke outlet, or mouthpiece, which is attached to the casting forniing the bottom of the retort, is fitted with a self-sealing lid. As no mechanical means of extracting the coke is provided, a safety door is fitted inside the discharging chamber, actuated by a hånd lever. By means of this the flow from the mouthpiece may be regulated as required. The coke outlet is fixed at such a height above the retort-house floor as to discharge direct into a tipping wagon or telpher skip and to enable the operator to manipulate with ease the mouthpiece lid and safety door. It will be seen that the producer is situated immediately under the retorts, having the feeding shoot so constructed so as to admit of its aperture being placed in the sidewalls of the retort beuch and immediately under the coke outlet of one of each pair of retorts. By means of a movable shoot the furnaces are charged direct from the retorts on one side of the setting. Clinkering is effected at the inner side in the space between the supporting walls of the setting. The heating is effected by means of a series of three horizontal combustion. chambers arranged between the side walls of the retorts. The gases rising from the producer meet the secondary air which may be admitted to any or all of the chambers and, passing upwards in a zigzag direction, are finally controlled by a damper before admission to the finishing flue connected to the chimney, there being one chimney to