A method for co-producing ammonia from melamine tail gas

Abstract

The invention relates to a method for co-production of ammonia water through melamine tail gas. The tail gas forms high-concentration ammonia water with the titer of 270 tt and the CO2 content of 140 ml / ml through absorption of an ejector, part of the high-concentration ammonia water is diluted to diluted ammonia water with the titer of 220 tt, the diluted ammonia water is sent to a decarbonization tower and heated to 144-146 DEG C, CO2 and NH3 in a liquid phase are desorbed out and subjected to three-level absorption with desalting washing water, CO2 gas is evaporated out of the tower top, low-carbonization-ratio ammonia water with the titer of 180 tt and the CO2 content of 30 ml / ml is prepared from NH3 absorbed by the water, the high-concentration ammonia water and the low-carbonization-ratio ammonia water are fed into an ammonia water mixing tank, and mixed ammonia water is qualified ammonia water when reaching the titer of 260 tt and the carbonization ratio of 70 ml / ml. The method has the advantages as follows: the melamine tail gas is used for preparing industrial ammonia water, so that the carbonization ratio of the mixed ammonia water is reduced by about 70%, and crystallization is avoided.

Description

technical field [0001] The invention relates to the technical field of melamine production, in particular to a method for recovering tail gas generated from melamine to make industrial ammonia water. Background technique [0002] At present, the tail gas recovery technology of domestic melamine manufacturers mainly focuses on co-production of ammonium bicarbonate and separation of ammonia and carbon. Due to the high production cost of ammonia-carbon separation, the actual operation is seldom, and the melamine tail gas of most manufacturers is used for the co-production of ammonium bicarbonate. However, in recent years, with the diversification of domestic agricultural fertilizers, the market for ammonium bicarbonate has shrunk sharply, and the market price has also declined a lot, with poor economic benefits. In addition, there is a seasonality in the production of ammonium bicarbonate. Once autumn and afternoon enter the off-season, there will be a large backlog of ammoniu...

AI Technical Summary

Problems solved by technology

The melamine tail gas is used to produce industrial ammonia water, but the melamine tail gas is directly absorbed to produce ammonia water, because the degree of carbonization in the ammonia water is high, it is easy to crystallize, and the pipeline is blocked

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