Separating carbon dioxide from natural gas liquids

Patent metadata

Field	Value
Publication number	US-9683777-B2
Application number	US-201314424386-A
Country	US
Kind code	B2
Filing date	Sep 30, 2013
Priority date	Oct 8, 2012
Publication date	Jun 20, 2017
Grant date	Jun 20, 2017

Abstract

Embodiments described herein provide a method and systems for separating carbon dioxide from heavy hydrocarbons. The method includes cooling a first liquid stream including carbon dioxide and heavy hydrocarbons within an oscillatory crystallization unit to generate carbon dioxide solids and a second liquid stream including the heavy hydrocarbons. The method also includes separating the carbon dioxide solids from the second liquid stream via a solid-liquid separation system.

First claim

What is claimed is:

1. A method for separating carbon dioxide from heavy hydrocarbons, comprising:
cooling a first liquid stream comprising carbon dioxide and heavy hydrocarbons within an oscillatory crystallization unit to generate carbon dioxide solids and a second liquid stream comprising the heavy hydrocarbons; and
separating the carbon dioxide solids from the second liquid stream via a solid-liquid separation system.

2. The method of claim 1 , comprising cooling the first liquid stream within a heat exchanger upstream of the oscillatory crystallization unit.

3. The method of claim 2 , wherein the first liquid stream is cooled to a temperature that is slightly higher than a freezing point of the carbon dioxide within the heat exchanger.

4. The method of claim 1 , comprising reducing a pressure of the first liquid stream via a pressure reducing device upstream of the oscillatory crystallization unit.

5. The method of claim 1 , wherein the first liquid stream is cooled to a temperature that is below a freezing point of the carbon dioxide within the oscillatory crystallization unit to generate the carbon dioxide solids.

6. The method of claim 1 , comprising separating the first liquid stream from a methane stream within a separation system upstream of the oscillatory crystallization unit.

7. The method of claim 6 , comprising:
flowing the methane stream from the separation system to a heat exchanger that is upstream of the oscillatory crystallization unit; and
using the methane stream to cool the first liquid stream within the heat exchanger.

8. The method of claim 6 , comprising:
flowing the methane stream from the separation system to the oscillatory crystallization unit; and
using the methane stream to cool the first liquid stream within the oscillatory crystallization unit.

9. The method of claim 1 , comprising separating hydrogen sulfide from the carbon dioxide solids along with the second liquid stream within the solid-liquid separation system.

10. The method of claim 1 , comprising:
separating residual carbon dioxide from the second liquid stream to generate a purified heavy hydrocarbon stream and an azeotropic mixture comprising carbon dioxide and heavy hydrocarbons; and
using the azeotropic mixture to cool the first liquid stream upstream of the oscillatory crystallization unit.

11. The method of claim 1 , comprising:
separating residual carbon dioxide from the second liquid stream to generate a purified heavy hydrocarbon stream and an azeotropic mixture comprising carbon dioxide and heavy hydrocarbons; and
recycling the azeotropic mixture to the oscillatory crystallization unit, wherein the oscillatory crystallization unit cools the azeotropic mixture to generate carbon dioxide solids and a third liquid stream comprising the heavy hydrocarbons.

12. The method of claim 1 , comprising producing pulsations within the first liquid stream.

13. A system for separating carbon dioxide from heavy hydrocarbons, comprising:
an oscillatory crystallization unit configured to cool a first liquid stream comprising carbon dioxide and heavy hydrocarbons to generate carbon dioxide solids and a second liquid stream comprising the heavy hydrocarbons; and
a solid-liquid separation system configured to separate the carbon dioxide solids from the second liquid stream.

14. The system of claim 13 , comprising a heat exchanger configured to cool the first liquid stream upstream of the oscillatory crystallization unit.

15. The system of claim 14 , wherein the heat exchanger is configured to cool the first liquid stream to a temperature that is slightly higher than a freezing point of the carbon dioxide.

16. The system of claim 13 , comprising a pressure reducing device configured to reduce a pressure of the first liquid stream upstream of the oscillatory crystallization unit.

17. The system of claim 13 , wherein the oscillatory crystallization unit is configured to cool the first liquid stream to a temperature that is below a freezing point of the carbon dioxide.

18. The system of claim 13 , comprising a separation system configured to produce the first liquid stream and a methane stream from a hydrocarbon feed stream.

19. The system of claim 18 , wherein the separation system comprises a methane separation system, controlled freeze zone (CFZ) column, a bulk fractionator, a Ryan-Holmes column, or a physical solvent system, or any combinations thereof.

20. The system of claim 13 , wherein the solid-liquid separation system is configured to separate hydrogen sulfide from the carbon dioxide solids along with the second liquid stream.

21. The system of claim 13 , comprising an azeotropic distillation system configured to separate residual carbon dioxide from the second liquid stream to generate a purified heavy hydrocarbon stream and an azeotropic mixture comprising carbon dioxide and heavy hydrocarbons.

Assignees

• Moorkanikkara Srinivas N
• Exxonmobil Upstream Res Co

Inventors

• Moorkanikkara Srinivas N

Classifications

• F25J3/0233

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

• Y02C10/12

  Cross-Sectional Technologies · mapped topic

• F25J3/0238

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

• C10L2290/543

  Distillation, fractionation or rectification for separating fractions, components or impurities during preparation or upgrading of a fuel · CPC title

• F25J2200/02

  in a single pressure main column system · CPC title