Method for refining coked crude ammonium sulfate through membrane crystallization

Abstract

The invention relates to a method for refining coked crude ammonium sulfate through membrane crystallization. The technical scheme is as follows: a pretreated coked crude ammonium sulfate crystal mother solution is delivered into a membrane module; water in the mother solution is condensed into liquid water at the other side of a membrane after penetrating through the membrane in a water vapor form through membrane distillation; a crystal mother solution leaving away from the membrane module is delivered into a crystallizer after being concentrated to be oversaturated; a crystal is fluidized to grow in a suspended way in the circular crystal mother solution; the crystal mother solution at the upper layer of the crystallizer is delivered into the membrane module through a pump and is internally circulated; a crystal product is led out of the bottom of the crystallizer, is subjected to solid-liquid separation and is dried to obtain an ammonium sulfate crystal. According to the invention, the crystal mother solution of the ammonium sulfate is evaporated and concentrated through membrane distillation so as to be oversaturated; the crystal grows in a fluidized bed crystallizer, so that a better condition is provided for the growth of the crystal; the fluidized bed crystallizer has a particle size grading effect, so that the grown ammonium sulfate crystal product is large and uniform in particle size. The method can also be used for effectively reducing the production cost for refining ammonium sulfate through recrystallization.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, coking and chemical industry, and in particular relates to a method for refining coking crude ammonium sulfate by membrane crystallization. Background technique [0002] Coking ammonium sulfate is a large industrial by-product of coke oven gas purification. my country's coke output ranks first in the world, and the domestic coking ammonium sulfate output is huge. Ammonium sulfate is an important nitrogen fertilizer, and it can also be used as a printing and dyeing agent, a food catalyst, and a leather deliming agent in industry. [0003] Domestic coking ammonium sulfate is mostly produced by the saturator method. Because of the influence of impurities, it is often gray, green, blue, dark black or red. The particle size does not exceed 0.5mm; and the moisture and acidity exceed the standard. Ammonium sulfate crystals are easy to absorb moisture and agglomerate, especially when the air humidi...

AI Technical Summary

Problems solved by technology

There is a temperature difference between the crystallization mother liquid surface and the main body area of ​​the mother liquid (or the heat exchange surface and the main body area of ​​the mother liquid during the cooling and crystallization process) during the evaporation crystallization process, which causes a temperature gradient in the mother liquid during the evaporation crystallization (or cooling crystallization) process, and the degree of supersaturation is not uniform. The grown crystals are not uniform in size