METHOD OF PURIFYING WASTE AIR FROM GRANULATION PLANT FOR PRODUCING UREA-CONTAINING GRANULATE

摘要

FIELD: methods of air cleaning.;SUBSTANCE: present invention relates to a method for cleaning granulated bed exhaust air for the production of urea-containing granulate, in which a gas stream with urea-containing dust and ammonia in contact with a sulphuric acid solution or a nitric acid solution during wet cleaning, wherein the wet scrubbing process includes at least two separate, successive wet scrubbing steps, wherein the gas stream in the first wet scrubbing step is cleaned with a first weakly acidic detergent solution, and the gas flow leaving the first wet scrubbing step is cleaned in the second wet scrubbing step with the second detergent solution having a lower pH than the first weakly acidic detergent solution.;EFFECT: according to the invention, the acidic detergent solution precipitated in the second wet scrubbing step is returned through a pipeline to the first wet scrubbing stage for use therein as a first weakly acidic detergent solution; except for this first stage of wet cleaning pre-wet cleaning is performed, in process of which significant fraction of dust is washed from gas flow.;15 cl, 1 dwg