GB1080240A - A process for the production of flue gas, having a relatively low no-content - Google Patents

Abstract

Flue gas (the gas obtained when hydrocarbons are burnt in air) which is to be added to a coal gas stream as diluent, is treated to remove nitric oxide by admixing it with ozone at a pressure of, at most, 6 atmospheres to convert the nitric oxide to nitrogen dioxide. The mixture is added to the coal gas stream prior to the removal of ammonia from the coal gas stream and the nitrogen dioxide is removed in the ammonia washing plants. The amount of ozone introduced may be increased to convert any sulphur dioxide in the flue gas to sulphur trioxide which is removed with the nitrogen dioxide. Alternatively, any sulphur dioxide in the flue gas may be removed before admixture with an ozone by scrubbing the flue gas with aqueous alkali, e.g. sodium carbonate.ALSO:Aprocess for the reduction of the nitric oxide content in flue gas (i.e. that gas obtained by the combustion of hydrocarbons in air) comprises supplying ozone to the flue gas at a pressure of, at most, 6 atmospheres and subsequently scrubbing the gas to remove the nitrogen dioxide formed. Before the flue gas is combined with the ozone it is preferably scrubbed with alkali, e.g. an aqueous solution of sodium carbonate, to remove any sulphur dioxide present. Alternatively, the SO2 may be converted to sulphur trioxide, by additional ozone, the sulphur trioxide being removed with the NO2. The scrubbing to remove NO2 may be with aqueous sodium carbonate or in the ammonia washing plants of a coal gas stream to which the flue gas has been added.