Method of increasing absorption ratio of free ammonia in tail gas from production process of urotropine

Abstract

The invention discloses a method of increasing absorption ratio of free ammonia in tail gas from production process of urotropine. The method includes steps of: feeding the tail gas with ammonia intoa formaldehyde absorption column via a pipeline from a tail gas absorption column; performing reaction absorption treatment and feeding unsaturated urotropine other liquid or ammonia water to an ammoniation reactor; and feeding processed tail gas into a tail gas boiler. In the method, without any increase on power cost, a circulating pump of the formaldehyde absorption column is used for chemicalreaction absorption. The method has high efficiency and is flexible and convenient to adjust, can recycle and reuse ammonia water, can reduce reaction heat in a reactor and save circulating water, andsatisfies industrial policy of reducing consumption and protecting environment in our country.

Description

technical field [0001] The invention relates to the technical field of industrial tail gas recovery, in particular to a method for improving the absorption rate of free ammonia in the tail gas of the hexamethamine production process. Background technique [0002] In the current domestic gas-phase method of urotropine production process, the traditional gas-phase method of urotropine production process is formed by condensation of formaldehyde gas and ammonia gas in an alkaline solution (see the specific flow chart figure 1 ). In the actual production process, in order to make the reaction proceed in the direction of forming urotropine, and avoid side reactions that affect product quality and raw material consumption, the reaction temperature is strictly controlled and the excess ammonia is ensured to be 1% to 2%. The inert gas, water vapor and incompletely reacted ammonia from the reactor pass through the ammonia absorption tower, most of the ammonia and water vapor are abs...

AI Technical Summary

Problems solved by technology

However, the existing packed tower is limited by its small liquid holding capacity and short liquid holding time, so it often uses liquid phase to circulate, but this method completely destroys the absorption tower plate by plate absorption to form a concentration gradient mechanism, and the ammonia water at the bottom of the tower is injected into the tower The concentration gradient of the liquid phase is formed at the top, and the tray effect completely disappears

In this way, the absorption of ammonia gas is not complete, and the unit consumption of large waste products is too high

In summer, if the temperature of the absorption tower is too high, the recovery effect will be poor, and improper control may lead to excessive ammonia nitrogen emissions after combustion of the tail gas boiler

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