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A dynamic self-cleaning reactor and its method for preparing isocyanate

A reactor and self-cleaning technology, applied in chemical methods, chemical instruments and methods, preparation of isocyanic acid derivatives, etc. for the reaction of liquids and gaseous media, to reduce the production of by-products, prolong the operation period, and realize dynamic Self-cleaning effect

Active Publication Date: 2017-07-21
WANHUA CHEM GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The process of preparing isocyanate by gas-phase phosgenation is a fast reaction process. Even at an extremely fast mixing rate, the formation of high polymers such as by-product urea cannot be avoided. Therefore, it is necessary to find a method that can efficiently and quickly mix the reactants and can Reactor and method for effectively removing reaction deposits

Method used

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  • A dynamic self-cleaning reactor and its method for preparing isocyanate
  • A dynamic self-cleaning reactor and its method for preparing isocyanate
  • A dynamic self-cleaning reactor and its method for preparing isocyanate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0060] reactor:

[0061] use as figure 1 The dynamic self-cleaning reactor shown. It includes: housing 1, auxiliary feed port N3, scraper 2, support shaft 5, mixer, reaction area 3, outlet N4, the mixer is composed of inner feed pipe N1 and is located on the periphery of inner feed pipe N1 and The outer feed pipe N2 coaxial with the inner feed pipe N1 is composed of an annular space 4 formed between the inner feed pipe N1 and the outer feed pipe N2, and the scraper 2 rotates around the support shaft 5 to clean the inner feed The outlet of the pipe N1, the outlet of the outer feed pipe N2 and the side wall 6 of the reaction zone 3, and the auxiliary feed inlet N3 is located on the side wall 6 of the reaction zone 3.

[0062] The reactor is provided with 4 sets of mixers; the axes of each set of mixers are parallel to the axis of the reactor, and the axes of each set of mixers are evenly distributed on a virtual circle 8 with a radius of 250mm, and the radius r of the reaction...

Embodiment 2

[0070] The dynamic self-cleaning reactor adopted has 2 sets of mixers, the axes of each set of mixers are evenly distributed on a virtual circle 8 with a radius of 200mm, the number of auxiliary feed inlets N3 is 3, and the number of each auxiliary feed inlet N3 The distance L between the axis and the axis of the reactor is 200 mm. The scraper 2 has 6 scrapers, the scrapers are directly connected by the radial scraper and the axial scraper, there is no oblique scraper, the cross sections of the radial scraper and the axial scraper are both right-angled trapezoids, and the angle α of the right-angled trapezoid is 35° , the angle β is 40°; the length of L1 is 80mm, the thickness W of the scraper is 20mm, the length of L3 is 80mm; the length L2 of the radial scraper is 500mm; the height H of the axial scraper is 450mm. All the other structures are with the reactor of embodiment 1.

[0071] The same reaction conditions as in Example 1 for the preparation of isocyanates were used....

Embodiment 3

[0073] The dynamic self-cleaning reactor adopted has 6 sets of mixers, and the axes of the mixers are evenly distributed on a virtual circle 8 with a radius of 300 mm. The distance L of the reactor axis is 250 mm. The scraper has 8 scrapers, the length of L1 is 75mm, the thickness W of the scraper is 25mm, the length of L3 is 60mm; the length L2 of the radial scraper is 400mm; the height H of the axial scraper is 450mm, and the length L4 of the oblique scraper is 150mm. All the other structures are with the reactor of embodiment 1.

[0074] The same reaction conditions as in Example 1 for the preparation of isocyanates were used. Analysis by gas chromatography showed that H 12 The yield of MDI was 97.9%. After a long period of operation, after 3.6 months of operation, the machine was shut down for maintenance, and no obvious coking was found at the outlet of the mixer and the side wall of the reaction area.

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Abstract

The invention provides a dynamic self-cleaning reactor and a method for preparing isocyanate through gas-phase phosgenation reaction using the reactor. The dynamic self-cleaning reactor includes a shell (1), an auxiliary feed inlet (N3), a scraper (2), a support shaft (5), a mixer, and a reaction zone (3), and the mixer is fed from the inside The pipe (N1) and the outer feed pipe (N2) located on the periphery of the inner feed pipe (N1) and coaxial with the inner feed pipe (N1) are composed, and the scraper (2) can rotate around the support shaft (5) ; The phosgene that enters from the auxiliary feed port (N3) forms a swirl, strengthens the vortex, strengthens the rapid mixing and reaction of the amine vapor and phosgene, reduces the generation of reaction by-products, and provides rotating power to the scraper to clean up the reactor. deposits, prolonging the operating cycle.

Description

technical field [0001] The invention relates to a reactor for preparing isocyanate, in particular to a dynamic self-cleaning reactor and a method for preparing isocyanate using the reactor. Background technique [0002] The gas phase phosgenation method to prepare isocyanate was reported in the 1940s. The gas phase reaction process is often carried out in a tubular reactor, which has the characteristics of fast reaction rate and low phosgene retention. When it is slow, more polymerization by-products are generated. These by-products coke and agglomerate on the wall of the reactor, and eventually block the reactor. Especially, the material is more likely to produce coke at the first contact point, which leads to mixed flow field The gradual deterioration of the reactor shortens the operating period of the reactor. Therefore, on the one hand, it is necessary to strengthen the mixing during the high-temperature reaction process and shorten the residence time; on the other hand...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01J10/00C07C263/10C07C265/14
Inventor 李同和尚永华孙中平韩海涛孙积钊黎源华卫琦
Owner WANHUA CHEM GRP CO LTD