Urea granulation process with scrubbing system

摘要

Disclosed is a method for producing granular urea and reducing ammonia emissions in a gaseous waste stream of the urea granulation process. The method includes the steps of granulating urea and generating a gaseous waste stream from the granulation of the urea, first washing the waste stream in a first scrubber dust stage to remove dust form the gaseous waste stream, and then reacting the gaseous waste stream with formaldehyde in a formaldehyde stage to generate a hexamethylenetetramine and urea-formaldehyde liquid stream, and an ammonia-reduced off-gas stream.

主权项

1. A method for reducing ammonia emissions in a gaseous waste stream of a process for producing granular urea, comprising:
granulating urea by the operation of a urea granulator; generating a dust and ammonia laden gaseous waste stream by the operation of the urea granulator; washing, in a first scrubber dust stage, the gaseous waste stream with at least one of water or an aqueous urea solution to generate a dust-laden liquid stream and a dust-reduced gas stream; after said washing step, reacting, in a formaldehyde stage, the dust-reduced gas stream with formaldehyde to generate a hexamethylenetetramine and urea-formaldehyde liquid stream, and an ammonia-reduced off-gas stream.