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Crystallization separation method of 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 crystallizer scaling, pre-cooler scaling, and high energy consumption, and achieve refrigeration energy saving and good performance. Technical effect, the effect of solving serious fouling

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 large energy consumption, serious fouling of the precooler and serious fouling of the crystallizer in the existing crystallization method for separating p-xylene, and a new crystallization method for separating p-xylene is provided , the separation of p-xylene by this method has the advantages of low energy consumption, light fouling of precooler and crystallizer

Method used

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  • Crystallization separation method of p-xylene
  • Crystallization separation method of p-xylene

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Embodiment 1

[0024] A crystallization method for separating p-xylene according to the present invention.

[0025] 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 5375kg / h, a part of the mixed xylene raw material c enters the crystallizer 4 for crystallization, the flow rate is 1075kg / h, the temperature is 15°C, and the crystallization temperature is -17°C. The magma in the kettle-type crystallizer 4 flows out in two parts, and the magma d returns to the kettle-type crystallizer 4 after heat exchange in the casing-type crystallizer 5, and its flow rate is 57m 3 / h, the magma e is concentrated by the thickening device 6 to obtain the pre-separated mother liquor f and the concentrated ma...

Embodiment 2

[0027] The crystallization method of separation p-xylene of the present invention

[0028] According to the operating condition of embodiment 1, adopt as figure 2 The crystallization method for separating p-xylene, wherein the weight ratio of the pre-separation mother liquor f to the crystallization and filtration mother liquor i is 0.87:1. The specific results are shown in Table 1.

Embodiment 3

[0030] A crystallization method for separating p-xylene according to the present invention.

[0031] According to the operating condition of embodiment 1, adopt as image 3 The crystallization method for separating p-xylene, wherein the weight ratio of the pre-separation mother liquor f to the crystallization and filtration mother liquor i is 1:1. The specific results are shown in Table 1.

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Abstract

The invention relates to a crystallization and separation method for p-xylene, and mainly solves the problems that energy consumption is large, pre-cooler fouling is server and a crystal is difficult to wash in the prior art. According to the crystallization and separation method, a mixed xylene raw material enters a raw material intermediate tank; one part of the raw material I is processed by a mother liquid heat exchanger, is cooled by a pre-cooler and returns to the raw material intermediate tank, and the other part of the raw material II enters a kettle-type crystallizer for crystallization; magma in the kettle-type crystallizer flows out by dividing into two portions, 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, wherein the weight ratio of the magma I to the magma II is 1-100:1; and the concentrated magma is separated by a solid-liquid separator for obtaining p-xylene crystal and a crystallization filtered mother liquid. 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 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 Patents(China)
IPC IPC(8): C07C15/08C07C7/14
Inventor 陈亮肖剑顾军民钟思青张鸿翔
Owner CHINA PETROLEUM & CHEM CORP
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