Separating carbon dioxide and ethane from a mixed stream

Patent metadata

Field	Value
Publication number	US-10323879-B2
Application number	US-201815944323-A
Country	US
Kind code	B2
Filing date	Apr 3, 2018
Priority date	Mar 21, 2012
Publication date	Jun 18, 2019
Grant date	Jun 18, 2019

Abstract

Embodiments described herein provide methods and systems for separating a mixed ethane and CO 2 . A method described includes generating a liquid stream including ethane and CO 2 . The liquid stream is flashed to form an ethane vapor stream and solid CO 2 . The solid CO 2 is accumulated in an accumulation vessel and the gas is removed from the top of the accumulation vessel.

First claim

What is claimed is:

1. A system for separating a mixed stream of CO 2 and ethane, comprising:
a purification system configured to remove contaminants from the mixed stream and generate a liquid stream comprising an azeotropic mixture of ethane and CO 2 ;
a flash valve configured to isoenthalpically flash the liquid stream forming solid CO 2 and a vapor stream enhanced in ethane; and
an accumulation vessel configured to capture the solid CO 2 ;
a compressor and a chiller configured to recondense the vapor stream forming a condensed gas;
a fractionator configured to remove a contaminated ethane stream, comprising ethane, methane, and CO 2 , from the condensed gas;
a flash vessel configured to separate methane from the contaminated ethane stream, thereby forming a remainder stream that comprises ethane and CO 2 , wherein the remainder stream is combined with the liquid stream;
wherein the accumulation vessel has an outlet valve and a heater, the heater configured to
warm the solid CO 2 in the accumulation vessel and drive off trapped hydrocarbon therein when the outlet valve is open, and
melt the solid CO 2 in the accumulation vessel when the outlet valve is closed, thereby forming a liquid CO 2 product stream.

2. The system of claim 1 , comprising a separation system configured to form the mixed stream from a natural gas feed.

3. The system of claim 1 , wherein the fractionator is configured to isolate a liquid ethane product stream.

4. The system of claim 1 , wherein the accumulation vessel is one of a plurality of sequentially arranged accumulation vessels, and wherein each sequential accumulation vessel is configured to begin accumulating solid CO 2 when a previous accumulation vessel is filled with CO 2 .

5. The system of claim 1 , wherein the accumulation vessel is configured to reach a temperature and pressure that allows the solid CO 2 to melt, forming a liquid CO 2 product stream.

Assignees

• Oelfke Russell H
• Exxonmobil Upstream Res Co

Inventors

• Oelfke Russell H

Classifications

• F25J2280/30

  Control of a discontinuous or intermittent ("batch") process · CPC title

• F25J3/0209

  Natural gas or substitute natural gas · CPC title

• F25J2280/40

  Control of freezing of components · CPC title

• F25J2205/04

  in the feed line, i.e. upstream of the fractionation step · CPC title

• F25J3/0233

  separation of CnHm with 1 carbon atom or more · CPC title