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Crystallization method for separating paraxylene

A technology of p-xylene and mixed xylene, which is applied in crystallization purification/separation, organic chemistry, etc., and can solve problems such as high energy consumption and fouling of pre-coolers

Active Publication Date: 2014-05-07
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is the problems of high energy consumption and serious fouling of the precooler in the existing crystallization method for separating p-xylene, and a new crystallization method for separating p-xylene is provided

Method used

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Examples

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Embodiment 1

[0019] Such as 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%, and a part of the mixed xylene raw material b passes through the mother liquor heat exchanger 2 and the precooler 3 Return to the raw material tundish 1 after cooling, the flow rate is 5375 kg / h, a part of the mixed xylene raw material c enters the crystallizer 4 for crystallization, the flow rate is 1075 kg / h, the temperature is 15°C, and the crystallization temperature is -17°C. The crystal slurry d in the crystallizer 4 is separated by the solid-liquid separator 5 to obtain p-xylene crystals e and crystallization and filtration mother liquor f. P-xylene crystal e is melted in melting tank 6, and melting temperature is 20 ℃, and the p-xylene of 20% by weight is used as washing liquid g to wash the crystal in solid-liquid separator 5, and the p-xylene of 80% by weight is used as product h enters pr...

Embodiment 2

[0022] According to the operating condition of embodiment 1, adopt as figure 1 In the crystallization method for separating p-xylene, the flow rate of mixed xylene raw material b is 10750 kg / h. The specific results are shown in Table 1.

[0023]

Embodiment 3

[0025] According to the operating condition of embodiment 1, adopt as figure 1 In the crystallization method for separating p-xylene, the flow rate of mixed xylene raw material b is 16125kg / h. The specific results are shown in Table 1.

[0026]

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Abstract

The invention relates to a crystallization method for separating paraxylene, which mainly solves the problems of high energy consumption and serious scaling of a precooler in the prior art. The method employs the technical scheme that a mixed xylene raw material enters a raw material intermediate tank; a part of raw material I returns to the raw material intermediate tank after cooled by a mother solution heat exchanger and a precooler; a part of raw material II enters a crystallizer for crystallization; crystal pulp in the crystallizer is separated by a solid-liquid separator to form a paraxylene crystal and crystallization filtrated mother solution; the paraxylene crystal is molten after heated in a fusion tank; 5-30wt% of paraxylene returns to the solid-liquid separator as a cleaning solution; the rest enters a product tank as a product; 0-100wt% of crystallization filtrated mother solution I returns to the crystallizer; and the rest crystallization filtrated mother solution II enters a mother solution tank after the mother solution heat exchanger cools the mixed xylene raw material I. Therefore, the problems are better solved, and the method can be used for crystallization production of paraxylene.

Description

technical field [0001] The invention relates to a crystallization method for separating 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 pro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C15/08C07C7/14
Inventor 陈亮肖剑钟思青顾军民张鸿翔
Owner CHINA PETROLEUM & CHEM CORP
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