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Crystallization method of p-xylene

A p-xylene and crystallization technology, applied in the field of p-xylene crystallization, can solve the problems of difficult crystal washing, serious fouling of the pre-cooler, high energy consumption, etc., achieve good technical effects, save refrigeration energy consumption, and solve the problem of Severe effect of scale

Active Publication Date: 2015-12-23
CHINA PETROLEUM & CHEM CORP +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] 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 p-xylene is provided

Method used

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Examples

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Effect test

Embodiment 1

[0025] The crystallization method for separating p-xylene according to the present invention.

[0026] Such as figure 1 Said mixed xylene raw material a enters the raw material intermediate tank 1, the temperature is 30°C, the flow rate is 1075kg / h, the p-xylene content is 80wt%, and a part of the raw material b is pre-cooled by the mother liquid heat exchanger 2 and the precooler 3. Then return to the raw material intermediate tank 1 with a flow rate of 5375 kg / h, and a part of the raw material c enters the crystal slurry tank 4 to raise the temperature of the crystal. The flow rate is 1075 kg / h and the temperature is 15°C. The operating temperature of the crystal slurry tank 4 is 3.5°C. The overflow mother liquor d flows out from the upper part into the kettle crystallizer 8 for crystallization. The concentrated crystal slurry e is separated by the solid-liquid separator 5 to obtain filtered mother liquor f and p-xylene crystals g. The filtered mother liquor f enters the kettle...

Embodiment 2

[0028] The crystallization method for producing p-xylene according to the present invention.

[0029] According to the operating conditions of Example 1, using figure 2 In the crystallization method for producing p-xylene, the flow rate of the mixed xylene raw material b is 10750 kg / h.

Embodiment 3

[0031] The crystallization method for producing p-xylene according to the present invention.

[0032] According to the operating conditions of Example 1, using image 3 In the crystallization method for producing p-xylene, the flow rate of the mixed xylene raw material b is 16125 kg / h.

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Abstract

The invention relates to a crystallization method for p-xylene, and mainly solves the problems that energy consumption is large, precooler fouling is server and a crystal is difficult to wash in the prior art. According to the crystallization method, a mixed xylene raw material enters a raw material intermediate tank; an overflow mother liquid in a magma tank flows out from the upper part and enters a kettle-type crystallizer for crystallization, concentrated magma flows out from the lower part and is separated by a solid-liquid separator for obtaining a filtered mother liquid and p-xylene crystal, and the filtered mother liquid enters the kettle-type crystallizer for crystallization; the p-xylene crystal is heated and melt in a fusion tank; magma in the kettle-type crystallizer is divided into two portions and flows out, magma I is subjected to heat exchange by a casing pipe type crystallizer and returns to the kettle-type crystallizer, and magma II is concentrated by a thickening device for obtaining a pre-separated mother liquid and concentrated magma; and the concentrated magma is separated by the solid-liquid separator for obtaining p-xylene crystal and a crystallization filtered mother liquid, and p-xylene crystal returns to the magma tank. The technical scheme relatively well solves the problems and is applicable to industrial production of p-xylene.

Description

Technical field [0001] The invention relates to a crystallization method of p-xylene. Background technique [0002] Paraxylene is an important raw material in the polyester industry, mainly used to produce purified terephthalic acid (PTA) or purified dimethyl terephthalate (DMT), and then PTA and DMT to produce polyester (PET), separation Mixed xylene is the main production method of p-xylene. Mixed xylene is mainly composed of p-xylene, meta-xylene, o-xylene and ethylbenzene. The boiling point difference between the components is very 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. The method first precools the mixed xylene raw materials through a precooler, and then separates the high-purity p-xylene product through a single-stage crystallization process. In the actual crystallization production process, the temperature of the r...

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
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