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P-xylene crystal separation method

A technology of para-xylene and crystallization separation, applied in the direction of crystallization separation, crystallization purification/separation, solution crystallization, etc., can solve the problems of raw material liquid disturbance, unfavorable crystal growth, affecting crystallization efficiency, etc.

Active Publication Date: 2018-11-13
CHONGQING THREE GORGES UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The invention provides a method for crystallization and separation of p-xylene, which solves the problem that the raw material liquid will be greatly disturbed during the mixing process of the low-temperature liquid and the raw material liquid, which is not conducive to the growth of crystals and affects the crystallization efficiency.

Method used

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Examples

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Embodiment 1

[0026] A method for crystallization and separation of p-xylene, the device structure for crystallization and separation of p-xylene is as follows Figure 1-2 ,and Figure 4 Shown, as follows: comprise crystallization tank 1 and condensing tube, the upper end of crystallization tank 1 is provided with feed port 11 and exhaust port 12, and the lower end of crystallization tank 1 is provided with discharge port 13, and crystallization tank 1 has the second left and right relative One side wall and the second side wall, a row of first through holes 14 is provided longitudinally along the first side wall, and a row of second through holes 15 is provided longitudinally along the second side wall, and the first through holes 14 and the second The two piercing holes 15 form a pair of perforations according to the order from top to bottom. There are several pairs of perforations in total. The condensation pipes pass through the pairs of perforations in turn to form a liquid passage, an...

Embodiment 2

[0032] A method for crystallization and separation of p-xylene, the structure of the device for crystallization and separation of p-xylene is basically the same as that of Example 1, the difference is that in Example 2, the positions of the first through hole 14 and the second through hole 15 are One by one, the line between the pair of perforations formed by two is inclined by 70 degrees with respect to the vertical axis of the crystallization tank 1 . The hole diameter of the liquid flow microhole 41 is 2mm. The structure of the device for crystallization and separation of p-xylene in embodiment 2 is as figure 1 and Figure 3-4 shown.

[0033] The crystallization and separation operation is basically the same as in Example 1, except that in Example 2, the inert cooling liquid is liquid carbon dioxide. The main components in the mixed xylene liquid raw material are C8 aromatic hydrocarbons m-xylene, o-xylene and C10 aromatic hydrocarbons, and the mass fraction of p-xylene ...

Embodiment 3

[0036]A method for crystallization and separation of p-xylene, the structure of the device for crystallization and separation of p-xylene is the same as in Example 1.

[0037] The crystallization and separation operation is basically the same as in Example 1, except that in Example 2, the inert cooling liquid is liquid carbon dioxide. The main components in the mixed xylene liquid raw material are C8 aromatic hydrocarbon m-xylene, ortho-xylene and C10 aromatic hydrocarbon, and the mass fraction of p-xylene in the mixed xylene liquid raw material is 5%.

[0038] In Example 3, the temperature of the liquid carbon dioxide is controlled to be about -10°C. When the crystal content in the crystallization tank 1 reaches 4.5% of the raw material quality, the material is discharged and the crystal is recovered. The purity of p-xylene in the finally measured crystal is 99.8% %; The total recovery rate of final p-xylene is 94.3%.

[0039] It should be noted that, in order to avoid exces...

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Abstract

The invention belongs to the technical field of p-xylene crystals and in particular relates to a p-xylene crystal separation method. The invention designs a special p-xylene crystal separation deviceand a corresponding method. The device structurally comprises a crystallization tank and a condensation tube, wherein a feeding hole, an exhaust hole and a discharge hole are formed in the crystallization tank; the condensation tube penetrates through the crystallization tank; parts of the condensation tube are retained inside and outside the crystallization tank respectively; a plurality of flowing liquid micropores are formed in the condensation tube inside the crystallization tank. As the condensation tube penetrates through the crystallization tank, a mixed p-xylene liquid raw material canbe subjected to heat exchange and cooling inside and outside simultaneously; in addition, due to design of the flowing liquid micropores, an inert cooling liquid slowly infiltrates into the crystallization tank from different heights in a micro-flowing process, then the raw material liquid is not seriously disturbed, growth of the crystal can be facilitated, the crystal purity and product yieldscan be increased, the crystallization time is shortened, and the equipment production intensity is improved.

Description

technical field [0001] The invention belongs to the technical field of p-xylene crystallization, and in particular relates to a method for crystallizing and separating p-xylene. Background technique [0002] P-xylene is an important raw material for the polyester industry, mainly used to produce purified terephthalic acid or purified dimethyl terephthalate, and then use the two to produce polyester. In the production process of p-xylene, a mixture of p-xylene, m-xylene, o-xylene and ethylbenzene will be produced. At present, there are two main technological processes for industrial separation of p-xylene: adsorption separation method and crystallization classification method. Because the boiling point difference between the components of the p-xylene-containing mixture is small, the melting point difference is relatively large, so the crystallization method is one of the commonly used methods for separating p-xylene. [0003] Chinese patent CN 104030880 B discloses a metho...

Claims

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Application Information

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IPC IPC(8): C07C15/08C07C7/14B01D9/02
CPCB01D9/0013B01D2009/0086C07C7/14C07C15/08
Inventor 黄美英赖庆轲李廷真蒋德敏梁克中陈星谢永生
Owner CHONGQING THREE GORGES UNIV
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