A kind of processing method of melamine tail gas

Abstract

The invention discloses a method for treating melamine tail gas. The method comprises the following steps: introducing the tail gas into an ammonium carbamate solution gas-liquid separator for condensing, wherein a liquid phase urea removal production device introduces a gase phase into a two-circulating one-cooling system of the urea device capable of recovering the melamine tail gas according to the specific components of the gas phase when the air mass percentage is low; recycling the formed dilute ammonium carbamate solution; and introducing the gas phase into an ammonium scrubber of melamine when the air mass percentage is high enough, and allowing the washed water to enter a recycling system. According to the arrangement, carbon dioxide can be prevented from entering a melamine scrubbing system, so that the content of the carbon dioxide in melamine recycled water is reduced, and the load of the ammonium scrubber of melamine is reduced; and selection is performed according to actual conditions, so that the production control flexibility is improved, and emptying up-to-standard release is guaranteed.

Description

technical field [0001] The invention belongs to the field of melamine production in chemical production, and in particular relates to a method for treating melamine tail gas. Background technique [0002] In the high-pressure method (7-10MPa) melamine production process, tail gas containing ammonia, carbon dioxide and water will be produced. There are many methods for the treatment of tail gas, among which the co-production of urea solution is reused as the raw material of melamine, which is a very Good method. Usually, the tail gas is directly condensed into methyl ammonium liquid, and the liquid phase is used to produce urea solution; the gas phase is washed with ammonia, and the washed water enters the recycling system. During the treatment, if the concentration of the liquid phase is high, the content of ammonia and carbon dioxide in the gas phase will increase, which will increase the load of the ammonia scrubbing system, resulting in unqualified recycling water system...

AI Technical Summary

Problems solved by technology

During processing, if the concentration of liquid phase is high, the content of ammonia and carbon dioxide in the gas phase will increase, increasing the load of the ammonia scrubbing system, resulting in unqualified recycling water system or unqualified atmospheric emissions

In order to make the ammonia scrubbing system qualified, the lower temperature should be controlled, and the melamine tail gas is usually diluted to avoid crystallization causing blockage of pipelines and equipment. At this time, the obtained liquid phase has low component concentration and low urea conversion rate. Disadvantages of low energy consumption, poor operation stability, and increased energy consumption