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Crystallization method for p-xylene

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

Active Publication Date: 2014-06-25
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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Effect test

Embodiment 1

[0026] A crystallization method for separating p-xylene according to the present invention.

[0027] 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 tank 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 kettle crystallizer 8 for crystallization, the crystallization temp...

Embodiment 2

[0030] The crystallization method of producing p-xylene described in the present invention.

[0031] According to the operating condition of embodiment 1, adopt as figure 2 In the crystallization method for producing p-xylene, the flow rate of mixed xylene raw material b is 10750 kg / h.

[0032]

Embodiment 3

[0034] The crystallization method of producing p-xylene described in the present invention.

[0035] According to the operating condition of embodiment 1, adopt as image 3 In the crystallization method for producing p-xylene, the flow rate of mixed xylene raw material b is 16125kg / h.

[0036]

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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 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 proc...

Claims

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Application Information

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