Modern Gasworks Practice

750 MODERN GASWORKS PRACTICE that is, a wood fire is first kindled and the coke-bed is gradually built up on this. When the fires in both generators are thoroughly started, and the coke is on a level with the secondary air inlets, the air blast is admitted below the fuel in (say) the right-hand generator and above the fuel in the left-hand generator. For the sake of simplicity in describing the operations, it will be of advantage to designate the right-hand generator as No. 1, the left-hand being No. 2. Before blowing is commenced, the stack-valve on No. 1 generator is, of course, shut, whereas that on No. 2 generator is opened. In this way, the direct air-blast raises to a certaia extent the temperature of the fuel-bed in No. 1 generator, but, as combustion is incomplete, a stream of producer gas is passing through, the top connecting tube into the second generator. This combustible gas then comes into contact with the secondary air blast, and its conscqucnt combustion provides sufficient heat for raising the temperature of the fuel in this generator. The hot gases pass downwards through the coke-bed, and then away through the open stack-valve. It is advisable to secure, as far as possible, nearly equal temperatures in both vessels, and in order to do this the sequence of generators is reversed after a period of about two minutes. Thus the primary blast is admitted to No. 2 generator, and the producer gas meets with the secondary air in the top of No. 1. By heating the generators in. this way for some time a temperature sufficiently high for gasmaking is obtained. Cycle of Operations In the Rincker-Wolter plant the gasmaking “ nm ” usually lasts for about six minutes, but it is unique in that no steam is admitted to the generators during the first half of the period. Before the “ iun ” is commenced, the various air valves and flue dampers are necessarily closed, and a passage is made for the gas by opening the valve at the outlet of the hydraulic main or “ dipper.” The generators are, of course, always operated in series for blowing, whilst gasmaking is carried on in each one alternately. Assuming that a “ run ” has just commenced in No. 1 generator, then the oil, or other carburetting agent employed, after passing through a meter, is sprayed on to the coke in this generator. On coming into contact with the incandescent coke the oil is immediately gasified, and passes off through the bottom of the generator to the hydraulic main, where the tarry matter and particles of carbon are retained. At the expiration of about three minutes the oil is shut off and steam is blown through the same spray —partly for cleaning purposes—for a period of about seventy-five seconds. The No. 1 “ dipper ” valve is then closed, the corresponding valve on No. 2 being opened. Steam is then injected under the firebars of No. 1 generator for one minute, and the gas produced passes through the connecting pipe and second fuel-bed to the opposite hydraulic main. The steam is now shut off, and gives way to a blast of air, which. is continued for a few seconds, and thoroughly scours the apparatus. From the above description it may appear that a somewhat complicated series of operations are comprised in the ‘ ‘ run. ” The cycle is, of course, more or less intricate