Process for removing light components from an ethylene stream

Patent metadata

Field	Value
Publication number	US-11255604-B2
Application number	US-201816106490-A
Country	US
Kind code	B2
Filing date	Aug 21, 2018
Priority date	Dec 13, 2012
Publication date	Feb 22, 2022
Grant date	Feb 22, 2022

Abstract

A process for removing light components from an ethylene stream may include providing a dried ethylene stream containing ethylene, ethane, CO, CO2, H2, CH4, and C3+ hydrocarbons. The process may include sending the dried ethylene stream to a stripper to produce an overhead stream containing ethylene, CO, H2 and CH4, and a bottom stream containing ethylene, ethane, CO2, and C3+ hydrocarbons. The gaseous phase on top of the stripper may be condensed in a heat exchanger cooled by a refrigerant stream to get a first gaseous phase and a first liquid phase. The first gaseous phase may be condensed in a heat exchanger cooled by liquid ethane or liquid ethylene to get a second gaseous phase containing ethylene CO, H2 and CH4 and a second liquid phase. The first and second liquid phases may be the reflux of the stripper.

First claim

The invention claimed is:

1. A process for removing light components from an ethylene stream comprising:
a) providing a dried ethylene stream (A) comprising ethylene, ethane, CO, CO 2 , H 2 , CH 4 , C 3+ hydrocarbons and optionally oxygenates;
b) separating said dried ethylene stream (A) in a separation means that is a demethanizer or a stripper to form:
an overhead gaseous stream (B) comprising ethylene, CO, H 2 and CH 4 ; and
a bottom stream (C) comprising ethylene, ethane, CO 2 , C 3+ hydrocarbons and optionally oxygenates;

c) cooling the overhead gaseous stream (B) to a temperature ranging from −10° C. to −45° C. to form a first gaseous stream (D) and a first liquid stream (E), wherein the cooling is performed with a refrigerant stream that comprises a mixture of liquid and optionally C 3 to C 4 gaseous hydrocarbons in a first condenser;
d) further cooling the first gaseous stream (D) to a temperature ranging from −10° C. to −45° C. lower than the temperature of step c) to get a second gaseous stream (F) comprising ethylene CO, H 2 and CH 4 and a second liquid stream (G), wherein the cooling is performed with liquid ethane or liquid ethylene in a second condenser, wherein the liquid ethane or the liquid ethylene has a pressure ranging from 30 kPag to 500 kPag;
e) sending the first and second liquid streams (E) and (G) to the separation means as a reflux and;
either
i)
f) sending said bottom stream of step b) to a deethanizer to produce:
a bottom stream comprising ethane, C 3+ hydrocarbons and optionally oxygenates; and
an overhead stream consisting of ethylene and CO 2 , wherein a portion of a liquid ethylene in a reflux drum of the deethanizer is expanded and used for the cooling in (d); and

d) sending said overhead of step f) to a fixed bed CO 2 adsorption zone to recover an ethylene stream free of CO 2 ;
or
(ii)
f1) sending said bottom stream of step b) to a fixed bed CO 2 adsorption zone to recover a stream free of CO 2 , then sending said stream free of CO 2 to a deethanizer to produce:
a bottom stream comprising ethane, C 3+ hydrocarbons and optionally oxygenates; and

an overhead stream consisting of ethylene free of CO 2 .

2. The process according to claim 1 , wherein the refrigerant stream comprises liquid and optionally gaseous propane and/or liquid and optionally gaseous propylene, wherein the liquid propane or the liquid propylene has a pressure ranging from 30 kPag to 200 kPag.

3. The process according to claim 1 , wherein during the cooling of the first gaseous stream (D) the liquid ethylene in step (d) returns to gas phase and is recycled.

Assignees

• Total Res & Technology Feluy
• Ifp Energies Now

Inventors

• Vermeiren Walter
• Boutrot Catherine
• Arratia Manuela

Classifications

• B01D3/343 Primary

  the substance being a gas · CPC title

• C07C7/04

  by distillation · CPC title

• C07C7/005

  Processes comprising at least two steps in series · CPC title

• F25J3/0238 Primary

  separation of CnHm with 2 carbon atoms or more · CPC title

• C07C1/24

  by elimination of water · CPC title