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Method for producing p-xylene

A technology of p-xylene and mixed xylene, which is applied in the direction of crystallization purification/separation, organic chemistry, etc., can solve the problems of high energy consumption, serious fouling of the pre-cooler, and difficult crystal washing, so as to save energy consumption of refrigeration and solve the problem of Severe fouling and good technical effect

Active Publication Date: 2015-07-08
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is the problems of high energy consumption, serious fouling of the precooler and difficult crystal washing in the existing crystallization method for producing p-xylene, and a new crystallization method for producing p-xylene is provided

Method used

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  • Method for producing p-xylene
  • Method for producing p-xylene

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Embodiment 1

[0016] The crystallization method of producing p-xylene described in the present invention.

[0017] like figure 1 Said, the mixed xylene raw material a enters the raw material tundish 1, the temperature is 30°C, the flow rate is 1075kg / h, the p-xylene content is 80wt%, a part of the raw material b is pre-cooled by the mother liquid heat exchanger 2 and the precooler 3 After returning to the raw material tundish 1, the flow rate is 5375 kg / h, a part of raw material c enters the crystal slurry tank 4 to heat up the crystal, the flow rate is 1075 kg / h, and the temperature is 15°C. The operating temperature of the magma tank 4 is 3.5° C. The overflow mother liquor d flows out from the top into the crystallizer 8 for crystallization, and the concentrated magma e is separated by the solid-liquid separator 5 to obtain the filtered mother liquor f and p-xylene crystals g. The filtered mother liquor f enters the crystallizer 8 for crystallization, the crystallization temperature is -...

Embodiment 2

[0019] The crystallization method of producing p-xylene described in the present invention.

[0020] According to the operating condition of embodiment 1, adopt as figure 1 In the crystallization method for producing p-xylene, the flow rate of mixed xylene raw material b is 10750 kg / h.

Embodiment 3

[0022] The crystallization method of producing p-xylene described in the present invention.

[0023] According to the operating condition of embodiment 1, adopt as figure 1 In the crystallization method for producing p-xylene, the flow rate of mixed xylene raw material b is 16125kg / h.

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Abstract

The invention relates to a method for producing p-xylene. The problems of high energy consumption, serious scaling of a precooler and difficulty in crystal washing in the prior art are mainly solved. According to the technical scheme, the method comprises the following steps: feeding mixed xylene raw materials into a raw material intermediate tank, cooling a part of raw materials I by using a mother liquor heat exchanger and the precooler, returning the raw materials I into the raw material intermediate tank, and causing a part of raw materials II to enter a crystal slurry tank; causing overflow mother liquor in the crystal slurry tank to flow out of the upper part and enter a crystallizer for crystallization, causing concentrated crystal slurry to flow out of the lower part, performing separation to obtain filtered mother liquor and p-xylene crystals by using a solid-liquid separator, and causing the filtered mother liquor to enter the primary crystallizer for crystallization; heating and melting the p-xylene crystals in a melting tank; separating the crystal slurry in the crystallizer to obtain p-xylene crystals and crystallized-filtered mother liquor, and returning the p-xylene crystals into the crystal slurry tank; dividing the crystallized-filtered mother liquor into two jets, returning the first jet into the crystallizer, and causing the second jet to enter a mother liquor tank after mixed p-xylene raw materials I are cooled through a mother liquor heat exchanger. According to the method, the problems are well solved; the method can be used for p-xylene crystallization production.

Description

technical field [0001] The present invention relates to a method for producing p-xylene. Background technique [0002] Paraxylene is an important raw material for the polyester industry, mainly used to produce purified terephthalic acid (PTA) or purified dimethyl terephthalate (DMT), and then produce polyester (PET) from PTA and DMT, and separate Mixed xylene is the main production method of p-xylene. Mixed xylenes are mainly composed of p-xylene, m-xylene, o-xylene and ethylbenzene. The difference between the boiling points of each component is small, but the difference in melting point is large. The crystallization method can be used to separate p-xylene. [0003] Patent US5498822 discloses a crystallization method for separating p-xylene. In this method, the raw material of mixed xylene is pre-cooled by a precooler, and then a high-purity p-xylene product is obtained by separating through a single-stage crystallization process. In the actual crystallization production p...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C15/08C07C7/14
Inventor 陈亮肖剑张鸿翔
Owner CHINA PETROLEUM & CHEM CORP