Method for recovering heat integrated solvent in continuous production of toluene di-isocyanate

A technology of toluene diisocyanate and recovery method, which is applied in the direction of purification/separation of isocyanic acid derivatives, climate sustainability, sustainable manufacturing/processing, etc., can solve the problem of a large amount of materials to be processed, reduce heat consumption, reduce Production cost and energy consumption reduction effect

Active Publication Date: 2010-03-17
TIANJIN UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, since the operating pressure of the first distillation tower is higher than that of the second distillation tower, and the amount of processed materials in the first distillation tower is large, a large amount of energy consumption during solvent recovery is actually concentrated in the reboiler at the bottom of the first distillation tower

Method used

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  • Method for recovering heat integrated solvent in continuous production of toluene di-isocyanate
  • Method for recovering heat integrated solvent in continuous production of toluene di-isocyanate
  • Method for recovering heat integrated solvent in continuous production of toluene di-isocyanate

Examples

Experimental program
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Embodiment 1

[0052] Recovery method of solvent o-dichlorobenzene in the continuous production of toluene diisocyanate without heat integration:

[0053] The material to be distilled that comprises toluene diisocyanate and inert organic solvent comes from hydrogen chloride stripping section, and flow rate is 96100kg / hr, 180 ℃ of temperature, absolute pressure 380kPa, and wherein o-dichlorobenzene (ODCB) mass content is 91.6%, toluene diisocyanate ( TDI) mass content is 7.8%, also has a small amount of phosgene, carbon tetrachloride and tar in addition. The material to be distilled passes through a two-stage solvent removal tower to remove the solvent. The first solvent removal tower is a packed tower with a theoretical plate number of 30. It is operated at an absolute pressure of 18kPa at the top of the tower. The side line extracts pure ODCB at 76400kg / hr, wherein the TDI content is less than 27ppb (mass fraction), and the phosgene content is less than 2ppm (mass fraction). The steam at th...

Embodiment 2

[0057] Embodiment 2 is a heat-integrated solvent recovery method in the continuous production of toluene diisocyanate.

[0058] The material to be distilled comprising toluene diisocyanate and an inert organic solvent is the same as in Example 1.

[0059] The material to be distilled comprising toluene diisocyanate and an inert organic solvent is exchanged with the crude product at the outlet of the phosgenation reactor with a flow rate of 151906kg / hr, and the temperature of the material to be distilled after the heat exchange is reduced to 120°C. The ratio of % will divide the material to be distilled after the heat exchange into two parts, and distill as the feedstock of the first solvent removal tower (solvent is o-dichlorobenzene (ODCB)) and the second solvent removal tower respectively, and the first solvent removal tower The removal tower is a packed tower with a theoretical plate number of 30, operated at an absolute pressure of 21kPa at the top of the tower, and the ab...

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Abstract

The invention discloses a method for recovering heat integrated solvent in the continuous production of toluene di-isocyanate, comprising the following steps: respectively importing materials to be distilled, which contains the toluene di-isocyanate and an inert organic solvent, to a first solvent eliminating tower with higher operation pressure and a second solvent eliminating tower with lower operation pressure to carry out distillation; leading steam from the top of the first solvent eliminating tower into a first condenser and leading part of tower bottom liquid in the second solvent eliminating tower into the first condenser to carry out heat transferring; and leading part of the tower bottom liquid from the first solvent eliminating tower and the second solvent eliminating tower intoa third solvent eliminating tower to carry out distillation. The method can obviously reduce the energy consumption in the production of the toluene di-isocyanate, thereby reducing the production cost of a unit toluene di-isocyanate product.

Description

technical field [0001] The invention relates to a solvent recovery method in the continuous production of toluene diisocyanate. Background technique [0002] Polyurethane materials have the characteristics of convenient modification, easy processing and molding, and simple construction, and are extremely widely used in various fields such as heat insulation, shockproof, sound insulation, cushion materials, packaging, and light structures. Isocyanate is an important monomer raw material in the polyurethane industry. The method of preparing isocyanate by phosgenation of primary amine has been reported many times in patents, and has been carried out on a large scale in industry, especially aromatic isocyanate TDI (toluene diisocyanate), The reactions that may occur during its preparation are as follows: [0003] [0004] [0005] TDI+urea→TDI biuret (7) [0006] TDI+TDI biuret → polyurea (8) [0007] Reactions (1), (2) are the main reactions that generate toluene diiso...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C265/14C07C263/20
CPCY02P20/50
Inventor 张金利闫少伟李韡李改英徐双庆杨富荣辛峰韩优
Owner TIANJIN UNIV
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