Energy recovery from mother liquid in paraxylene crystallization process

a technology of paraxylene crystallization and mother liquor, which is applied in the direction of separation processes, indirect heat exchangers, lighting and heating apparatus, etc., can solve the problems of limiting the efficiency of the crystallization process, difficult separation of high purity xylene isomers by conventional distillation, and significant amount of mother liquor from the process. to achieve the effect of optimizing energy recovery

Inactive Publication Date: 2012-09-20
GTC TECHNOLOGY US LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0008]In various embodiments, methods for recovering energy from mother liquor in paraxylene crystallization process are disclosed. The methods comprise: 1) providing a crystallizer or heat exchanger to recover energy from low temperature mother liquor; 2) providing a second heat exchanger to recovery energy from intermediate temperature mother liquor; 3) providing a third heat exchanger to recovery energy from high temperature mother liquor. The feed stream is the media on the other side of the heat exchangers / crystallizers that carries the energy, and the feed stream is cooled down by the mother liquor. One option is to have a fourth heat exchanger for the feed stream between the first crystallizer / heat exchanger and second heat exchanger to further optimize the energy recovery.

Problems solved by technology

Many physical properties of the individual xylene isomers are similar, such as boiling points, which makes the separation of high purity xylene isomers extremely difficult by conventional distillation.
The equilibrium of PX in C8 aromatics liquid (mother liquor) limits the efficiency of the crystallization process.
Thus, the mother liquor from the process contains significant amount of refrigeration duty due to its low temperature and high flow rate.

Method used

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  • Energy recovery from mother liquid in paraxylene crystallization process

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Embodiment Construction

[0013]In the following description, certain details are set forth such as specific quantities, and temperature, so as to provide a thorough understanding of the present embodiments disclosed herein. However, it will be obvious to those skilled in the art that the present disclosure may be practiced without such specific details. In many cases, details concerning such considerations and the like have been omitted inasmuch as such details are not necessary to obtain a complete understanding of the present disclosure and are within the skills of persons of ordinary skill in the relevant art.

[0014]In the PX crystallization process, the main energy consumption is from the refrigeration station compressors, which are used to provide the low temperature refrigerant duty to cool the feed streams to desired temperature. It is desirable to minimize the refrigeration duty by recovering energy from different streams within the crystallization unit before discharge.

[0015]For a PX crystallization...

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Abstract

Methods for recovering energy from a mother liquor stream in paraxylene crystallization processes are disclosed herein. The low temperature energy from the mother liquor is optimally utilized to reduce the refrigeration burden on the crystallization process.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]This Application claims the benefit under 35 U.S.C. 119(e) of U.S. Provisional Patent Application Ser. No. 61 / 454,337 filed Mar. 18, 2011, which is incorporated herein by reference in its entirety as if fully set forth herein.TECHNICAL FIELD OF THE INVENTION[0002]The claimed invention is directed to methods for recovering energy from a mother liquor stream in paraxylene crystallization processes. In the claimed invention, the energy from the mother liquor is optimally utilized to reduce the refrigeration burden on the crystallization process.BACKGROUND OF THE INVENTION[0003]Xylene isomers, ortho-xylene (OX), meta-xylene (MX), and para-xylene (PX), and ethylbenzene (EB) are C8 aromatics from a reforming process or other petrochemical processes. Generally, the product distribution for an equilibrium xylene mixture is about 40% MX, 20% PX, 20% OX and 20% EB. These amounts can vary by ±10%. The purified individual xylene products are used on...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): F28D15/00
CPCB01D9/0013C07C7/14C07C15/08Y02P20/10Y02P20/50B01J8/20B01D9/00B01J8/00F28D15/00
Inventor JIN, WEIHUADING, ZHONGYI
Owner GTC TECHNOLOGY US LLC
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