Modern Gasworks Practice

776 MODERN GASWORKS PRACTICE The Tully Gas Plant The Tully plant (Fig. 466) is practically a vertical retort fixed over a water gas producer. The fuel passes down the retort through various stages of carboni-zation, entering the producer in the form of coke which is then gasified as in the usual water gas apparatus. The plant is brought into operation as follows:— The producer is filled with. liot fuel up to the bottom of the retort, it is then blown to incandescence, the blast entering below the grate and leaving at special nostrils at the bottom of the retort, at which point the secondary air is admitted, making a combustible mixture, and heating the chequer work round the retort. After one or two runs the plant is charged with coal to a point about 2 feet from the top of the retort. The blast is then admitted as before, until a flame appears at the snift valve, which indicates that producer gases are being made in excess of the quantity burnt in the chequer work. At this point the blast is shut off by means of an operating wheel which automatically closes the main blast, secondary air, and snift valve. The top outlet lever on the washbox is then opened, the one operation opening up steam supply to the bottom of the producer and aHowing the gases to pass up through the producer, through the retort, then down through top outlet pipe, through the washbox, thence to the serubber and relief holder. After five or six minutes’ gasmakmg the plant is again blown to incandescence ; and, after the closing of air valves and snift valve, the bottom outlet lever on the washbox is opened up, which in this case admits steam in the chequer work at the top of generator. The gases travel down and out at the bottom of the producer, thence away througli washbox and serubber to the relief holder. The highest output as yet oTbtained from the Tully plant is a make of 63,000 cubic feet of gas of 360 to 370 B.Th.IL per cubic foot, and 8 to 9 gallons of tar per ton of coal. Broädhead’s Process Broadhead 1 proposes to employ a plant for producing mixed coal gas and water gas as illustrated in Fig. 467. Air is first blown into the combustion chamber of a generator, above which. a vertical retort, surrounded by a chamber containing chequer briekwork, is provided. The resultant gases pass through, this chamber to heat the retort. When the generator is sufficiently heated the air is shiit ofl and steam is passed through the incandescent fuel in the combustion chamber, the resultant gases passing through the coal contained in the retort. The objéct of the invention is to provide a process of maimfacture wliereby the two gases may be produced at the same time in an economical manner, and a low-teniperatiire produc-tion of tar oil may be effected. Witb. this object in. view, coal is fed into the retort between the steam runs and the coal descending the retort is subjected to a low-temperatnre carbonization by the heat from the water gas, together with the heat transferred during the air blow to the chamber surrounding the retort. 1 E.P. 122,179/19.