GB944810A - Continuous process for the preparation of hydrogen - Google Patents

Abstract

Hydrogen is prepared by a continuous process comprising charging steam and fluidized particles comprising a metalliferous steam-reducing agent, i.e. a metal or metal oxide, to a reaction zone, reacting the steam and fluidized particles at a temperature of 540-815 DEG C. to form hydrogen and oxides of the metalliferous steam reducing agent, continually withdrawing a hydrogen containing gaseous product stream from the reaction zone, passing the fluidized particles in an oxidized state together with a combustible gas mixture comprising a reducing gas and a gas containing free oxygen to a heating zone where they are heated to a temperature of 760-980 DEG C. by the ignition of the combustible gas mixture, passing the hot particles to a separate regeneration zone maintained at 705-935 DEG C., charging a freshly introduced gaseous hydrocarbon as reducing gas to the regeneration zone at a rate to provide, as spent reducing gas from the regeneration zone, the fuel component of the combustible gas mixture and to ensure a CO2/CO ratio below 0.33 by volume in the spent reducing gas, withdrawing the spent reducing gas from the regeneration zone and passing sufficient thereof to the heating zone in combination with a gas containing free oxygen to form the combustible gas mixture and withdrawing the fluidized particles from the regeneration zone in a reduced state and returning them to the <PICT:0944810/C1/1> heating zone. The metalliferous steam reducing agent may be lithium, rubidium, strontium, barium, calcium, magnesium, beryllium, aluminium, manganese, zinc, chromium, iron, cadmium, cobalt, nickel, tin, lead, copper or a lower oxide thereof which may be on a support, e.g. aluminia, silica, zirconia, boria or thoria or silica-alumina or silica-alumina-zirconia. In the drawing, steam is charged to the lower section of the reaction zone 1 through line 2 and is contacted with the counter-current flow, other fluidized particles comprising the metalliferous steam reducing agent. The hydrogen and steam pass upwardly through the reaction zone through particle separator 3 and leave the reaction zone through line 4 and the fluidized particles leave through control valve 5 and are carried to the heating zone 7 through line 6 by means of a lifting gas, e.g. steam or air. The first air mixture is supplied to the heating zone through line 8 and the resulting flue gas is passed through particle separator 9 and leaves through line 10. The heated particles pass downwardly to the regeneration zone 12 to contact a counter current flow of reducing gas, e.g. methane, ethane, propane, n-butane or isobutane or a mixture thereof or natural gas, introduced through line 13. The reducing gas passes upwards through particle separator 14, through line 15 to mixture control valve 29 where it is mixed with air introduced through line 17. The excess spent reducing gas is passed to water condenser 19 and carbon dioxide absorption unit 23 where water and carbon dioxide are removed and is then mixed with fresh reducing gas introduced through line 13 in line 24. Specifications 578,323, 586,914, 628,417, 639,554 and 645,140 are referred to.