CN-118085915-B - Separation wall rectification system and method for aromatic hydrocarbon combined device adsorption separation unit effluent

CN118085915BCN 118085915 BCN118085915 BCN 118085915BCN-118085915-B

Abstract

The invention relates to a partition wall rectification system for an aromatic hydrocarbon combined device adsorption separation unit extraction liquid, which comprises a partition wall rectification column, a toluene separation flow path, a paraxylene separation flow path and a paradiethylbenzene separation flow path, wherein the partition wall rectification column comprises a partition wall arranged in the column, one end of the partition wall is fixed at the bottom of the column, the other end of the partition wall extends upwards and is a certain distance away from the top of the column, the partition wall divides the column inner space into a first separation chamber and a second separation chamber which are arranged left and right, and a public rectification chamber which is positioned above the partition wall, the first separation chamber, the second separation chamber and the public rectification chamber are in fluid communication, the toluene separation flow path is connected with the top of the public rectification chamber, the paradiethylbenzene separation flow path is connected with the bottom of the first separation chamber, and the paraxylene separation flow path is connected with the bottom of the second separation chamber. Compared with the double-tower rectification process, the investment is greatly reduced, the cooling load of the tower top gas is small, the system waste heat is fully recycled, the energy consumption and the cost are reduced, and the economic benefit is generated.

Inventors

LI GUOQING
LI KE
QIN PEIGUANG

Assignees

华南理工大学

Dates

Publication Date: 20260512
Application Date: 20240122

Claims (8)

1. A partition wall rectification system for an aromatic hydrocarbon combined device adsorption separation unit extract is characterized by comprising a partition wall rectification tower, a toluene separation flow path, a paraxylene separation flow path and a paradiethylbenzene separation flow path; the separation wall rectifying tower comprises a separation wall arranged in the tower, one end of the separation wall is fixed at the bottom of the tower, the other end of the separation wall extends upwards and is kept at a certain distance from the tower top, the separation wall divides the space in the tower into a first separation chamber and a second separation chamber which are arranged left and right, and a public rectifying chamber which is positioned above the separation wall, the first separation chamber, the second separation chamber and the public rectifying chamber are in fluid communication, the side part of the first separation chamber is provided with a feed inlet for receiving the extraction liquid from the adsorption separation unit, the bottom of the first separation chamber is provided with a first discharge port, the bottom of the second separation chamber is provided with a second discharge port, and the top of the public rectifying chamber is provided with a third discharge port; The toluene separation flow path is connected with the top of the common rectification chamber and is used for separating toluene; the p-diethylbenzene separation flow path is connected with the bottom of the first separation chamber and is used for separating p-diethylbenzene; the para-xylene separation flow path is connected with the bottom of the second separation chamber and is used for separating para-xylene; The toluene separation flow path comprises a first heat exchanger, a heat pump compressor, a steam generator, a pressure reducing valve, an air cooler, a reflux tank and a reflux pump which are sequentially connected, wherein the first heat exchanger is connected with a third discharge port through a pipeline and is used for heat exchange between toluene and p-diethylbenzene, and the reflux pump is connected with a public rectifying chamber through a pipeline.
2. The separation wall rectification system for the effluent of an adsorption separation unit of an aromatic hydrocarbon combining apparatus as claimed in claim 1, wherein the separation flow path of the paradiethylbenzene comprises a first reboiler and a second heat exchanger, the first reboiler is circularly connected with the bottom of the first separation chamber, the first reboiler is used for heat exchange between the paradiethylbenzene and steam, the second heat exchanger is connected with the first discharge port through a pipeline, and the second heat exchanger is used for heat exchange between the effluent and the paradiethylbenzene.
3. The separation wall rectification system for the effluent of an adsorption separation unit of an aromatic hydrocarbon complex as claimed in claim 1, wherein said para-xylene separation flow path comprises a second reboiler in cyclic connection with the bottom of said second separation chamber, said second reboiler being adapted for heat exchange of para-xylene with steam.
4. The separation wall rectification system as claimed in claim 1, wherein a first reflux distribution plate and a second reflux distribution plate are rotatably arranged at the other end of the separation wall, the first reflux distribution plate is positioned at the top of the first separation chamber, and the second reflux distribution plate is positioned at the top of the second separation chamber.
5. The separation wall rectification system for the effluent of an adsorption separation unit of an aromatic hydrocarbon complex as claimed in claim 1, wherein a plurality of first plates are arranged in the first separation chamber at intervals in the vertical direction, a plurality of second plates are arranged in the second separation chamber at intervals in the vertical direction, the first plates and the second plates are horizontally arranged, and a plurality of third plates are arranged in the common rectification chamber at intervals in the vertical direction.
6. A separation wall rectification method for an aromatic hydrocarbon combined device adsorption separation unit effluent is characterized in that the separation wall rectification system for the aromatic hydrocarbon combined device adsorption separation unit effluent is adopted for rectification according to any one of claims 1-5, and comprises the following steps: After the extracted liquid is subjected to heat exchange through a second heat exchanger, the extracted liquid enters a first separation chamber from a feed inlet, reboiling heat is supplied through a first reboiler to separate the extracted liquid, the separated paradiethylbenzene is settled at the bottom of the first separation chamber and is discharged outside through a first discharge port, a paradiethylbenzene product is obtained, and a mixture containing paraxylene and toluene enters a public rectification chamber through the top of the first separation chamber; Toluene in the common rectification chamber is discharged through a third discharge port, and is subjected to heat exchange through a first heat exchanger, pressure boosting and temperature raising through a heat pump compressor, heat release through a steam generator, cooling through an air cooler and reflux through a reflux tank in sequence, cold reflux is carried out on the toluene, one part of the toluene after cold reflux is refluxed to the common rectification chamber, and the other part of the toluene is discharged to the outside to obtain a toluene product; and the paraxylene in the public rectifying chamber is settled to the bottom of the second separating chamber under the action of cold reflux, reboiled heat is supplied by the second reboiler to obtain paraxylene products, and the paraxylene products are discharged out through the second discharge port.
7. The method for separating and rectifying a liquid extracted from an adsorption separation unit of an aromatic hydrocarbon complex as claimed in claim 6, wherein the diethylbenzene product is subjected to heat exchange with the liquid extracted by the second heat exchanger and then subjected to heat exchange with toluene by the first heat exchanger.
8. The method for separating and rectifying aromatic hydrocarbon unit effluent as claimed in claim 6, wherein the pressure in the common rectifying chamber is 4-60kPag, the temperature in the common rectifying chamber is 100-130 ℃, the temperature in the reflux tank is 70-80 ℃, the liquid phase distribution ratio in the first separating chamber is 0.4-0.6, and the liquid phase distribution ratio in the second separating chamber is 0.4-0.6.

Description

Separation wall rectification system and method for aromatic hydrocarbon combined device adsorption separation unit effluent Technical Field The invention relates to the technical field of petrochemical industry, in particular to a separation wall rectification system and a separation wall rectification method for an aromatic hydrocarbon combined device adsorption separation unit extract. Background The aromatic hydrocarbon combined device is a core device for producing C 6-C8 low-carbon aromatic hydrocarbons (benzene, toluene and xylene) in petrochemical industry, and the device consists of 7 units of naphtha pretreatment, continuous reforming, isomerization, extraction, disproportionation, adsorption separation and xylene distillation. Wherein the adsorptive separation is to rectify the C 8 mixed aromatic hydrocarbon (abbreviated as C 8 A) from continuous reforming, isomerization and disproportionation to obtain the product Paraxylene (PX) with the purity of 99.80 percent. Wherein C 8 A comprises four isomers, namely paraxylene, orthoxylene, metaxylene and ethylbenzene, the boiling points of which are very close, and if the distillation process is directly carried out, the energy consumption is high, so that the adsorption separation process is adopted and then the distillation is carried out. In the adsorption separation process, the barium/potassium ion exchange zeolite molecular sieve is used as an adsorbent, the p-diethylbenzene is used as a desorbent, the adsorbent adsorbs PX from C 8 A, the desorbent is used for displacing the PX, and the extract rich in PX and p-diethylbenzene is distilled after adsorption separation. The distillation of the extract liquid generally adopts a double-tower rectification process of an extract liquid tower and a finished product tower, the extract liquid firstly enters the extract liquid tower, a desorbent is obtained from the bottom of the extract liquid tower, the distillate at the top of the tower enters the finished product tower, toluene (containing benzene and non-aromatic hydrocarbon and sent to a toluene disproportionation device) is obtained from the top of the separation tower, and high-purity para-xylene is obtained from the bottom of the tower. However, the double-column rectification process is high in investment, and the overhead gas (the extracted liquid overhead gas is about 152 ℃ and the finished product overhead gas is about 122 ℃) is cooled, so that the energy consumption is increased, and the operation cost is high. The prior art has some improvements, for example, the compression and temperature raising of the top gas of the liquid extraction tower is considered to produce steam, but the content of dimethylbenzene is high, liquid is easy to carry out during compression, and for example, the toluene content in the top gas of the finished product tower is considered to be high, and the liquid is difficult to compress, but the heat load is small, and the recovery value is low. Therefore, how to research a novel extraction liquid rectification process to reduce separation energy consumption is a problem which needs to be solved urgently at present. Disclosure of Invention Aiming at the technical problems in the prior art, the first object of the invention is to provide a partition wall rectification system for an aromatic hydrocarbon combined device adsorption separation unit extract, which comprises a partition wall rectification column, a toluene separation flow path, a paraxylene separation flow path and a paradiethylbenzene separation flow path, and compared with a double-column rectification process of an extract liquid column-finished product column, the overhead gas cooling load is less, the system waste heat can be fully recycled, the energy consumption and the cost are reduced, the investment is greatly reduced, and the economic benefit is generated. The second aim of the invention is to provide a separation wall rectification method for the aromatic hydrocarbon combined device adsorption separation unit effluent, which adopts the separation wall rectification system for the aromatic hydrocarbon combined device adsorption separation unit effluent to carry out rectification. In order to achieve the above purpose, the invention adopts the following technical scheme: A partition wall rectification system for an aromatic hydrocarbon combined device adsorption separation unit effluent comprises a partition wall rectification column, a toluene separation flow path, a para-xylene separation flow path and a para-diethylbenzene separation flow path, wherein the partition wall rectification column comprises a partition wall arranged in the column, one end of the partition wall is fixed at the bottom of the column, the other end of the partition wall extends upwards and is a certain distance away from the column top, the partition wall divides the column inner space into a first separation chamber and a second separation chamber which are arranged left a