METHOD AND SYSTEM FOR THE REDUCTION OF THE CONTENT OF AMMONIA IN FLUE GASES FROM PULP MILLS

摘要

The invention concerns a system for the reduction of ammonia in strong gases from pulp mills containing sulphur compounds (TRS). It is intended that the strong gases be destroyed in an oxidising environment without the formation of harmful nitrogen oxides. A liquid trap (1 a, 1 b) is inserted into the pipe system (20, 22, 23) for strong gases. Liquid is added to the gas scrubber and it maintains the liquid trap in a filled condition while the liquid circulates from the liquid trap to the gas scrubber and back again to the liquid trap, at the same time as a subfraction of the recirculated liquid is withdrawn (44) and new liquid (Liqi) is added to the liquid circulation in order to maintain the liquid level in the liquid trap. The liquid trap may also comprise an integrated gas scrubber (40) in one single unit. An obstacle to blow-back combustion is in this way formed, while an effective reduction in the level of ammonia in the strong gases is achieved at the same time. The amount of nitrogen oxides in the flue gases from a subsequent combustion plant for strong gases is in this way reduced.