GB191216855A - Improvements in the Production of Nitrogen from Products of Combustion. - Google Patents

Abstract

16,855. Harger, J. July 19. Nitrogen.-An inert gaseous mixture consisting principally or entirely of nitrogen and carbon dioxide, and which may be separated into its components, is prepared by passing a mixture of air and combustible gases in combining proportions, or the products of a carefully regulated combustion, under high pressure and relatively low temperature over a catalytic agent such as titaniferous bog iron ore, fireclay, or asbestos, with or without the employment of a mixture of copper and copper oxide which acts as an equilibrator. Preferably a gas-fired boiler is the source of the products of combustion, the catalyst being conveniently placed in the boiler tubes. The gases are delivered from an air-compressor and mixed in the right proportions for complete combustion, a convenient combustible being mine gas, containing a small proportion of methane, alone or mixed with producer-gas. A coal-dust fired boiler may also be used, or the exhaust from a gas - engine, except from an air - scavenged engine, or, less suitably, ordinary flue gases. For use, the bog iron ore may be mixed with fire-clay and moulded or burnt into small bricks &c. The heat of the burnt gases after passing over the catalyst may be used to heat feedwater, or the air and gas supply in the case of a gas-fired boiler. Any excess of oxygen in the gases passing from the catalyst is removed by the copper in the equilibrator, and any carbon monoxide is oxidized by the copper oxide. The equilibrator is preferably constructed to contain the catalyst and the copper and copper oxide in two compartments of the same apparatus, made of iron, the second compartment being fitted with a silica observation plate. Copper and copper oxide may be placed in the boiler tubes to act as both catalyst and equilibrator. The gases obtained are first scrubbed with limestone to remove sulphur dioxide, but sulphur compounds are preferably removed from the gas before reaching the gasengine, when such is used. The carbon dioxide is then extracted by compressing (if not already sufficiently compressed) and cooling the gases in presence of water, and finally cooling by expansion so that the dioxide is liquefied and can be trapped off, for example, by causing the compressed gases to expand while doing work in an air-engine, the exhaust from which is used to cool the compressed gas which is led to the air - engine, water being thoroughly removed from the compressed gas before being cooled. Heat evolved during compression may be used for heating feed-water &c. The gases which leave the motor are free from all traces of water or carbon monoxide and contain only a small quantity of carbon dioxide. Or the compressed mixed gases are cooled to air temperature and led away for use. Specification 28,075/11, [Class 1(i), Chemical processes &c.], is referred to.