GB964846A - Process and apparatus for the production of inert gases - Google Patents

Abstract

Inert gas substantially free from oxygen and oxides of nitrogen is produced by burning substantially completely a vaporous or gaseous hydrocarbon with air at a temperature of less than 800 DEG C., cooling the burnt gas, and recycling the major proportion thereof to the combustion zone in admixture with the air for combustion. The hydrocarbon may be propane or butane. The burnt gas may be cooled to 400 DEG C. Two-thirds of the burnt gas may be recycled. The pressure in the combustion zone <PICT:0964846/C1/1> <PICT:0964846/C1/2> may be maintained constant by a pressure valve in the burnt gas outlet conduit. The hydrocarbon and air may be fed to the combustion chamber at the same temperature. The combustion chamber may comprise a gas burner (Fig. 1) or a bed of oxidation catalyst (Fig. 3, not shown). In the former case, residual oxygen may be removed from the burnt gas by oxidation of residual and/or added hydrocarbon by catalysis. Preheating before catalytic reaction may be effected by an auxiliary burner or a heating element. As shown, air is forced by a fan 1 through a temperature equaliser 3, annular passage 7, and slits 4a into a combustion chamber 6 where it burns hydrocarbon admitted via pressure reducer 2, temperature equalizer 3, and gas ring 4. Cooling of the burnt gas is effected by a water-cooled coil 9. Most of the burnt gas is recycled via valve 11, fan 10 and annular passage 7. The remainder is mixed with a secondary stream of hydrocarbon through a line 12 and is passed through a catalytic reaction chamber 13 and a pressure control valve 16. Substantially pure nitrogen may be produced by removing water vapour and carbon dioxide from the inert gas.