Method for preparing ethylene with improved energy efficiency

• US 10,294,177 B2
• Filed: 04/07/2017
• Issued: 05/21/2019
• Est. Priority Date: 05/10/2016
• Status: Active Grant

• Current Assignee: LG Chem Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: Kim, Sung-Kyun, Lee, Sung-Kyu, Kim, Tae-Woo, Shin, Joon-Ho, Choo, Yeon-Uk, Park, Sa-Eun
• Primary Examiner(s): Pregler, Sharon
• Application Number:
  US15/762,426
• Publication Number:
  US 20180297915A1
• Time in Patent Office: 774 Days
• CPC Class Codes: C07C 11/04 Ethylene
• CPC Class Codes: C07C 11/24 Acetylene production of acetylene gas by wet methods C10H
• CPC Class Codes: C07C 5/08 of carbon-to-carbon triple bonds
• CPC Class Codes: C07C 5/09 to carbon-to-carbon double bonds
• CPC Class Codes: C07C 5/327 Formation of non-aromatic carbon-to-carbon double bonds only
• CPC Class Codes: C07C 7/005 Processes comprising at least two steps in series
• CPC Class Codes: C07C 7/04 by distillation
• CPC Class Codes: C07C 7/167 for removal of compounds containing a triple carbon-to-carbon bond
• CPC Class Codes: C07C 9/06 Ethane
• CPC Class Codes: Y02P 20/10 Process efficiency

Abstract

Provided is a method for preparing ethylene with improved energy efficiency which can reduce energy due to direct heat exchange between processes.

Claims

1. A method for preparing ethylene with improved energy efficiency, comprising:

providing a C2 compound isolated from a de-ethanizer column to an acetylene converter;

converting acetylene of the C2 compound into ethylene and ethane;

transferring the C2 compound containing ethylene and ethane converted from acetylene to a first C2 splitter to isolate and discharge a part of the ethylene; and

transferring a lower stream containing ethane and a remaining part of the ethylene of the C2 compound, which are not discharged from the first C2 splitter, to a second C2 splitter, to isolate and discharge the remaining part of the ethylene of the C2 compound, and converting the ethane of the C2 compound into ethylene to be recycled,

wherein a heat exchanger is installed between the de-ethanizer column and the first C2 splitter to perform direct heat exchange between the de-ethanizer column and the first C2 splitter, a difference in pressure between the de-ethanizer column and the first C2 splitter to enable the heat exchange is 4.5 kgf/cm² G or more, and a concentration of ethylene contained in the lower stream of the first C2 splitter is 70 to 80 mol %, and

wherein the heat exchange is performed between the lower stream of the first C2 splitter and an upper stream of the de-ethanizer column.

2. The method of claim 1, wherein a heat exchange amount obtained by the heat exchanger varies according to a difference (P1−

P2) between a pressure of the de-ethanizer column (P1) and a pressure (P2) of the first C2 splitter and a concentration (mol %) of the ethylene contained in the lower stream of the first C2 splitter.

3. The method of claim 1, wherein the difference between the pressure of the de-ethanizer column and the pressure of the first C2 splitter is 4.5 to 15 kgf/cm2 G.

4. The method of claim 1, wherein the lower stream of the first C2 splitter is transferred to the second C2 splitter or provided to the heat exchanger.

5. The method of claim 1, wherein the lower stream of the first C2 splitter allows a part of the upper vapor of the de-ethanizer column to be condensed after being provided to the heat exchanger.

6. The method of claim 1, wherein, when the heat exchange is performed between the de-ethanizer column and the first C2 splitter, an amount of a refrigerant used in the upper part of the de-ethanizer column is decreased.