GB544664A - Improvements in the manufacture of hydrogen - Google Patents

Abstract

544,664. Hydrogen. POWER-GAS CORPORATION, Ltd., GRISENTHWAITE, A. T., and RUTHERFORD, R. W. Nov. 14, 1940, No. 16484 [Class 90] In a process for the manufacture of hydrogen by the action of steam on an iron oxide contact material which has been reduced by a reducing gas, a reducing gas containing methane, e.g. town's gas, coke oven gas, or oil gas, is employed and a limited and controlled quantity of air is admitted to it before the reducing action for the purpose of converting some of the methane into carbon monoxide and hydrogen. Steam may be admitted in addition to the air. Town's gas containing 48 per cent. hydrogen, 24 per cent. methane and 7.5 per cent. carbon monoxide is mentioned. In the apparatus shown a hydrogen generator 1 contains an iron oxide bed 2 supported on a grate 3 and a superheater 4 consisting of refractory checker bricks. A combustion chamber 11 having a gas burner 12 is directly connected to the hydrogen generator. Reducing gas enters a booster 14 at 16 and air enters a blower 13 at 15. The process, which is cyclic, consists of (1) passing the methane-containing gas to burner 12 with valve 25 open, valve 26 being adjusted to give the required amount of air, and if desired valve 31 allowing steam to enter at 20 to increase the yield of carbon monoxide and hydrogen from the methane. The products of this partial combustion pass up through the oxide bed 2 and reduce it and thereafter are burned by opening valve 30 and passing in air ; thereafter they pass through and heat superheater 4 and leave through stack valve 10 and stack 5. (2) Steam purge. Valves 25, 26, 30, 31, 10 are closed, and 35, 33 opened. Steam from 17 passes down the generator and out through the purge pipe 18. (3) Valve 33 is closed and valve 34 opened and steam passed for the production of hydrogen, which, with admixed steam, leaves at 7 and passes through pipe 19 to the cooling and purification plant. During stages (2) and (3) gases from the generator may be prevented from passing to the combustion chamber by opening valve 32 and passing steam to a point 24, thus forming a steam curtain. (4) Impurities in the oxide bed 2 may be burnt off by air valves 35, 34 being closed and valves 33, 29 opened for this purpose so that air passes down through the generator and with the pro- 'ducts of combustion passes out at 18. This cycle is then repeated. The combustion chamber 11 may contain catalytic material to accelerate the decomposition of methane and it may contain checker brickwork to supply all the heat required for the generator, the brickwork in vessel 4 being omitted and the steaming of stage (2) taking place in the same direction as the flow of reducing gas. The initial partial combustion may be effected by admitting the burning portion of the gas at burner 12 and admitting another portion at 21 through valve 27. The partially burnt gases may be cooled by admitting some of the initial gas passed in at 23 by opening valve 28. In a modified apparatus, the cooling of the hot products of partial combustion leaving chamber 11 is carried out by a separate cooler. In this the cooling medium may be air or water. and the water may contact the hot gases and condense the water vapour therein.