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Method for recovering and preparing ammonium sulfate from acrylonitrile device

A technology of acrylonitrile and ammonium sulfate, applied in separation methods, ammonium sulfate, chemical instruments and methods, etc., can solve the problems of polymer outflow, polymer cannot float, liquid level disturbance, etc., to reduce reprocessing and save energy. Heating energy, reducing the effect of entrainment

Active Publication Date: 2014-11-05
CHINA TIANCHEN ENG +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In CN2867126, the polymer separator has been improved. A slanted partition is arranged on the upper part of the separator, and a baffle is arranged at the bottom. The feed liquid enters from the bottom, and the polymer overflows to the slanted partition to be discharged. The defect of this design is that If the opening between the two partitions is unreasonable or the upper part of the partition is washed and enlarged during operation, it is easy to cause the polymer to fail to float up to the inclined partition, and because the liquid level will be disturbed during the operation of the equipment, the polymer is easily entrained out in the mother liquor

Method used

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  • Method for recovering and preparing ammonium sulfate from acrylonitrile device
  • Method for recovering and preparing ammonium sulfate from acrylonitrile device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0049] The ammonium sulfate feed liquid that comes from the acrylonitrile device is sent to the first-effect evaporation chamber 3, and the feed liquid contains 22.5% of ammonium sulfate, 0.2% of acrylonitrile, 0.3% of acetonitrile, 0.3% of hydrocyanic acid, 2% of polymer, and the balance is water. The feed liquid is heated by the first-effect heat exchanger 2, and the first-effect operating pressure is 0.48MPa (A), and the operating temperature is 150°C. The concentration of the feed liquid evaporated through the first-effect is 45.0%, and the acrylonitrile, acetonitrile in the feed liquid and hydrocyanic acid impurities are steamed out, and the feed liquid is sent to the second-effect evaporation chamber 5. The heat source of the second-effect heat exchanger 4 is provided by the secondary steam evaporated from the first-effect evaporation chamber 3. The operating vacuum is controlled at 0.05MPa. The temperature is controlled at 81° C., the moisture therein is evaporated, and...

Embodiment 2

[0051] The ammonium sulfate feed liquid that comes from the acrylonitrile device is sent to the first-effect evaporation chamber 3, and the feed liquid contains 20.1% of ammonium sulfate, 0.3% of acrylonitrile, 0.1% of acetonitrile, 0.2% of hydrocyanic acid, 0.7% of polymer, and the balance is water. The feed liquid is heated by the first-effect heat exchanger 2, the first-effect operating pressure is 0.27MPa (A), and the operating temperature is 130°C. The feed liquid evaporated through the first-effect is 43.8%, and the acrylonitrile, acetonitrile and hydrogen in the feed liquid are The cyanic acid impurities are evaporated, and the feed liquid is sent to the second-effect evaporation chamber 5. The heat source of the second-effect heat exchanger 4 is provided by the secondary steam evaporated from the first-effect evaporation chamber 3. The operating vacuum degree is controlled at 0.077MPa, and the operating temperature is controlled At 70° C., the moisture therein was evap...

Embodiment 3

[0053] The ammonium sulfate feed liquid that comes from the acrylonitrile device is sent to the first-effect evaporation chamber 3, and the feed liquid contains 20.1% of ammonium sulfate, 0.3% of acrylonitrile, 0.1% of acetonitrile, 0.2% of hydrocyanic acid, 0.7% of polymer, and the balance is Water, the operating vacuum of the first-effect evaporation chamber 3 is 0.07MPa, and the operating temperature is 75°C. The concentration of the evaporated ammonium sulfate (supersaturated) solution is concentrated to 55.2%, and acrylonitrile, acetonitrile and hydrocyanic acid in the feed liquid Impurities evaporate. The ammonium sulfate (supersaturated) solution is extracted from the bottom of the evaporation chamber, sent to the thickener 8, centrifuged in the centrifuge 9, and dried in the drier 10 to obtain the finished product ammonium sulfate. The polymer in the feed liquid is removed in the separator 6, and the wastewater from the quenching tower is added to the mixer 7 at a rati...

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Abstract

The invention provides a method for recovering and preparing ammonium sulfate from an acrylonitrile device. An evaporator and a heat exchanger in vacuum direct-flow evaporation are used for evaporating and concentrating ammonium sulfate feed liquid containing acrylonitrile, acetonitrile, hydrocyanic acid and polymer impurities and from the acrylonitrile device, the acrylonitrile, the acetonitrile and the hydrocyanic acid in the feed liquid are evaporated out, the vapor is condensed and directly serves as make-up water of a quench tower of the acrylonitrile device, the polymer is separated and removed, and ammonium sulfate mother liquor is thickened and centrifuged to obtain finish products. The method improves energy utilization rate, saves heating energy, performs removing of light components, separation of the polymer and evaporation simultaneously and is few in operation procedure and short in process, and the direct-flow operation reduces conveying of a pump to the feed liquid and reduces operation cost of the device. The vapor is condensed and directly serves as the make-up water of the quench tower of the acrylonitrile device, so that complex following processing procedures are avoided, resources are saved, and comprehensive utilization of water is achieved.

Description

technical field [0001] The invention relates to a method for recovering and preparing ammonium sulfate from an acrylonitrile production device. Background technique [0002] In the production process of acrylonitrile, the unreacted ammonia gas in the reaction system enters the quenching tower and is neutralized with the sulfuric acid in the upper stage of the quenching tower to form ammonium sulfate. The mass fraction of ammonium sulfate in the upper stage can reach 20%-25%. The upper section of the tower is drawn out, and the dilute ammonium sulfate solution is sent to the ammonium sulfate recovery section. [0003] The dilute ammonium sulfate solution from the acrylonitrile plant mainly contains ammonium sulfate, and also contains a certain concentration of polymers generated in the production of acrylonitrile, traces of acrylonitrile, acetonitrile and hydrocyanic acid, and the solvent of the solution is water. [0004] For the treatment of the dilute ammonium sulfate sol...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01D1/00B01D1/26C01C1/24
Inventor 李强杨克俭马国栋耿玉侠陈宁李荣袁学民王美娇郑仁姚立东荣超赵峰
Owner CHINA TIANCHEN ENG