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Phosgene recovery method for toluene diisocyanate production process

A technology of toluene diisocyanate and recovery method, which is applied in carbonyl chloride, organic chemistry, etc., can solve the problems of toluene refining towers such as high hazards, increased lye consumption, and high HCl flow rate, so as to reduce corrosion damage, reduce mass fraction, and reduce The effect of the discharge of spent lye

Inactive Publication Date: 2009-01-21
GANSU YINGUANG CHEM IND GRP CO LTD
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Problems solved by technology

Excessive concentration of ethyl chloride will lead to a decrease in the concentration of phosgene, and ethyl chloride itself is explosive
[0007] (3) Due to the presence of trace amounts of water in the system, HCl and water in the material generate hydrochloric acid, which causes serious equipment corrosion, especially for the toluene desorption tower and toluene refining tower.
[0008] (4) The gas HCl flow rate from the top of the toluene absorption tower is very high, and it is directly discharged into the phosgene destruction tower to increase the consumption of lye

Method used

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  • Phosgene recovery method for toluene diisocyanate production process

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Embodiment Construction

[0012] The present invention relates to a method for recovering phosgene in the production process of toluene diisocyanate. The material containing HCl, ethyl chloride and phosgene is first absorbed by toluene, then the toluene absorption system is cooled, and the HCl non-condensable gas is absorbed by lye, and then The toluene absorption liquid that has absorbed ethyl chloride and phosgene is separated, and the separated toluene is recycled, and the phosgene destruction process is carried out on the separated phosgene material containing ethyl chloride, and the removed ethyl chloride is Neutralize with lye, and recycle the separated phosgene to the phosgene chamber.

[0013] As shown in Figure 1, the material containing HCl, ethyl chloride and phosgene enters the toluene absorption tower T1, and the phosgene is absorbed by toluene. The feed to the toluene absorption tower T1 is divided into two parts, one part enters from the bottom of the tower, and the other part enters from...

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Abstract

The invention provides a method for recovering phosgene in toluene diisocynate preparation process. In the method, materials containing HCl, ethyl chloride and phosgene are firstly absorbed by solvents containing benzene, cooled by toluene absorption system and has HCl fixed gases absorbed by alkaline liquors, toluene absorption liquids absorbing ethyl chloride and phosgene are subjected to separation, and the toluene obtained after separation is recovered; the phosgene materials containing ethyl chloride obtained after separation are subjected to phosgene destruction, ethyl chloride separated is neutralized by alkaline liquors, and the phosgene separated is recovered and returned back to a phosgene room.

Description

technical field [0001] The invention relates to a method for recovering phosgene in the production process of toluene diisocyanate (TDI). Background technique [0002] TDI (toluene diisocyanate) products are one of the most used isocyanate products in the world and one of the main raw materials of polyurethane. The TDI production process is mainly generated by the reaction of carbon monoxide provided by gas purification and chlorine gas provided by electrolysis of hydrochloric acid to generate phosgene (COCl 2 ), and then by TDA and COCl 2 Reverse generation of TDI (toluene diisocyanate), the main process includes phosgene synthesis, phosgenation, TDI rectification, phosgene recovery, solvent recovery, waste gas destruction and other units. [0003] At present, several large companies producing TDI in the world use their own proprietary technology, and all use the traditional phosgene method without exception. These companies are Bayer (BAYER), BASF (BASF), Dow Chemical (...

Claims

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Application Information

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IPC IPC(8): C01B31/28C07C265/14C01B32/80
Inventor 马建军王进军李晓明胡安魁强光明
Owner GANSU YINGUANG CHEM IND GRP CO LTD
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