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Method of producing p-xylene and heat exchanger network therein

A technology for para-xylene and xylene, which is applied in the field of separating para-xylene, can solve problems such as difficulty in adapting, and achieve significant effects of energy saving and consumption reduction.

Active Publication Date: 2016-08-10
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the eutectic mixture formed by mixed xylene at low temperature limits the maximum yield of p-xylene to only about 65%, so the crystallization separation method is gradually replaced by the adsorption separation method
However, when separating high-concentration p-xylene raw materials, the existing adsorption separation method will be difficult to adapt to, and the crystallization method has been favored again because of its advantages such as low energy consumption, high product purity, simple production equipment, and no use of solvents and separating agents. people's favor

Method used

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  • Method of producing p-xylene and heat exchanger network therein
  • Method of producing p-xylene and heat exchanger network therein
  • Method of producing p-xylene and heat exchanger network therein

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specific Embodiment approach

[0023] The invention adopts the method of coupling adsorption separation and crystallization separation to obtain high-purity p-xylene from mixed xylene and ethylbenzene, and provides a heat exchange network involved in realizing the method. The low-concentration p-xylene raw material is first separated by the adsorption separation process to obtain the higher-concentration p-xylene material, and then the high-purity p-xylene product is obtained by the method of crystallization separation.

[0024] In order to realize this process, a method for producing p-xylene is proposed, comprising:

[0025] (1) will contain C 8 The raw materials of aromatic hydrocarbons are passed into the xylene rectification tower to remove the C 9 The above hydrocarbons are obtained by the adsorption separation feed, and the adsorption separation feed and the deheptanizer feed are exchanged for heat and cooled down;

[0026] (2) passing the adsorption separation feed and the desorbent into the adsor...

Embodiment 1

[0061] with attached figure 2 As shown in the process flow of the method for producing xylene, there are 12 beds in the adsorption chamber of the adsorption separation unit, the operating temperature is 177°C, and p-diethylbenzene is used as the desorbent. The raw material is the mixture of reformate and C8 aromatics of disproportionation unit, (taken from the aromatics unit of Tianjin Branch of Sinopec Corporation, the composition or properties are shown in Table 1), and the C8 in the feed is controlled by the xylene rectification tower 9 + Heavy hydrocarbons are less than 0.5% by mass, and the concentration of paraxylene in the material supplied to the crystallization unit by adsorption is controlled at 95% by mass. The temperature of the crystallization separation unit was -10°C, and the product purity was 99.9% by mass. Table 2 below lists the use of this process figure 1 The main operating conditions of each tower in the shown process flow, and the energy consumption ...

Embodiment 2

[0071] with attached image 3 In the process flow of the method for producing xylene shown, the crystallization mother liquor directly enters the adsorption chamber after separating the toluene. The adsorption separation unit has 12 adsorption chamber beds, the operating temperature is 177°C, and p-diethylbenzene is used as the desorbent. The raw material is the same as in Example 1, and C in the adsorption feed is controlled by the xylene tower 9 + Heavy hydrocarbons are less than 0.05% by mass, and the concentration of paraxylene in the material supplied to the crystallization unit by adsorption is controlled at 90% by mass. The temperature range of the crystallization separation unit is -20°C, and the product purity is 99.8% by mass. Table 4 lists the main operating conditions of each tower, and Table 12 lists the energy consumption calculation results of Example 2.

[0072] Table 4

[0073]

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Abstract

A method of producing p-xylene and a heat exchanger network therein. The method includes the steps of: a) feeding a raw material comprising C8 aromatic hydrocarbon in a xylene rectification column to remove the hydrocarbons having more than nine carbon atoms to obtain an adsorption separation material; b) feeding the adsorption separation material into an adsorption separation chamber to perform adsorption separation to obtain an extract liquid and a raffinate liquid; c) feeding the extract liquid into an extract liquid column for distillation separation to obtain a material being rich in p-xylene on the top of the column, and performing crystallizing separation to obtain high-purity p-xylene product, wherein a desorption agent is obtained at the bottom; d) feeding the raffinate liquid into a raffinate liquid column for distillation separation, wherein a material from the top is fed into an isomerization reactor and the desorption agent is obtained at the bottom and is fed back to the adsorption separation material for being recycled; e) feeding an isomerization product to a heptane removal column for separation to obtain hydrocarbons having more than eight carbon atoms, which is then fed into the xylene rectification column. With the xylene rectification column as a core for heat integration to supply heat for the rectification columns, such as the extract liquid column, the raffinate liquid column and the heptane removal column, the method and the heat exchanger network fully utilizes the heat resource in the apparatus, reduces consumption of fuel, electricity and steam and has significant energy-saving and consumption-reducing effect.

Description

technical field [0001] The present invention relates to a method for separating p-xylene from C8 aromatic hydrocarbon mixture, in particular, a method for separating p-xylene using adsorption-crystallization combined process and its heat exchange network. Background technique [0002] Para-xylene (PX) is an important basic chemical raw material in the polyester industry. Separating and mixing xylene is the main method for producing para-xylene. Mixed xylene abbreviated as C 8 Aromatic fraction, which consists of para-xylene (PX), meta-xylene (MX), ortho-xylene (OX) and ethylbenzene (EB), etc., and the boiling point difference between the components is very small. Ethylbenzene is 136.2°C, p-xylene is 138.4°C, m-xylene is 139.1°C, and ortho-xylene is 144.4°C. Among them, the ortho-xylene with the highest boiling point can be separated by rectification, which requires hundreds of theoretical plates and a large reflux ratio. , ethylbenzene with the lowest boiling point can als...

Claims

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Application Information

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IPC IPC(8): C07C7/00C07C7/04C07C7/148C07C15/08F25J3/02
CPCY02P20/10
Inventor 李强王瑾邢波杨仁建李愿来
Owner CHINA PETROLEUM & CHEM CORP
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