Process Design For Acid Gas Removal

Patent metadata

Field	Value
Publication number	US-2017014753-A1
Application number	US-201615211672-A
Country	US
Kind code	A1
Filing date	Jul 15, 2016
Priority date	Jul 16, 2015
Publication date	Jan 19, 2017
Grant date	—

Abstract

A membrane permeation system and process accommodates varying acid gas inlet concentrations over time while utilizing only the initially installed equipment and still maintaining the non-permeate gas specification. The system and process provide flexibility to operate efficiently over a wide range of inlet CO 2 concentrations by adjustments to primary permeate, secondary permeate, and recycle gas operations. The glassy polymer membrane devices used in the system and process are selected so removal duty efficiency increases as acid gas concentration increase. Designing the system and process to handle about a 15% increase in acid gas concentrations over initial conditions effectively treats acid gas concentrations well above that 15% increase, thereby eliminating the need for additional equipment or for additional downstream amines and physical solvents.

First claim

What is claimed:

1 . A system comprising:
a primary membrane unit arranged to receive an inlet natural gas stream containing an acid gas and housing at least one glassy polymer membrane device; a compressor arranged to receive at least a portion of a permeate flow exiting the primary membrane unit; a bypass loop arranged to receive at least a portion of the permeate flow exiting the primary membrane unit; means for controlling the permeate flow to the compressor and the bypass loop; a secondary membrane unit arranged to receive a compressed permeate flow from the compressor and housing at least one glassy polymer membrane device; and a recycle loop having a compressor arranged to receive a non-permeate flow exiting the secondary membrane unit; wherein a total quantity “Q” of the glassy polymer membrane devices of the system is
Q=Y ( M B +N B ), XC B →C s
where “M B ” and “N B ” is a predetermined quantity of glassy polymer membrane devices in the primary and secondary units, respectively, effective to reduce an expected minimum acid gas content “C B ” of the inlet natural gas stream to a required non-permeate acid gas content specification “C s ; and where “Y(M B +N B )” is effective to reduce an acid gas content XC B of the inlet natural gas stream to the required non-permeate acid gas content specification C S when X≦Y and when X>Y, Y is in a range of 1.1 to 1.3; X is in a range of 1.0 to 3.5.

2 . A system according to claim 1 further comprising the at least one glassy polymer membrane device of the said membrane units being a spiral wound glassy polymer membrane device.

3 . A system according to claim 1 further comprising the at least one glassy polymer membrane device of the said membrane units being a hollow fiber glassy polymer membrane device.

4 . A system according to claim 1 further comprising the at least one glassy polymer membrane device of the said membrane units being a membrane selected from the group consisting of cellulose acetate, cellulose triacetate, polyimide, polyamide, polysulfone, and multi-layer composite.

5 . A system according to claim 1 further comprising a thermal oxidizer arranged to receive the portion of the permeate flow exiting the primary membrane unit and a permeate flow exiting the secondary membrane unit.

6 . A system according to claim 1 further comprising a low fuel gas system arranged to receive a portion of the non-permeate flow exiting the secondary membrane unit.

7 . A system according to claim 1 wherein 1.1≦Y≦1.2 and 1.15≦X≦3.5.

8 . A membrane permeation process to operate with varying acid gas inlet concentrations of a natural gas inlet stream over time while utilizing only the initially installed equipment and maintaining a same non-permeate gas specification over time, the process comprising the steps of:
passing an inlet gas stream through a primary membrane unit housing at least one glassy polymer membrane device; compressing at least a portion of a permeate flow exiting the primary membrane unit; optionally, routing a portion of the permeate flow existing the primary membrane unit to a bypass loop; removing an acid gas from the compressed permeate flow by passing the compressed permeate flow through a secondary membrane unit housing at least one glassy polymer membrane device; compressing at least a portion of a non-permeate flow exiting the secondary membrane unit; and recycling the compressed non-permeate flow to the inlet gas stream; wherein a total quantity “Q” of the glassy polymer membrane devices of the system is
Q=Y ( M B +N B ), XC B →C s
where “M B ” and “N B ” is a predetermined quantity of glassy polymer membrane devices in the primary and secondary membrane units, respectively, effective to reduce an expected minimum acid gas content “C B ” of the inlet natural gas stream to a required non-permeate acid gas content specification “C s ; and where “Y(M B +N B )” is effective to reduce an acid gas content XC B of the inlet natural gas stream to the required non-permeate acid gas content specification C S when X≦Y and when X>Y; Y is in a range of 1.1 to 1.3; X is in a range of 1.0 to 3.5.

9 . A process according to claim 8 wherein the at least one glassy polymer membrane device of the said membrane units is a spiral wound glassy polymer membrane device.

10 . A process according to claim 8 wherein the at least one glassy polymer membrane device of the said membrane units is a hollow fiber glassy polymer membrane device.

11 . A process according to claim 8 wherein the at least one glassy polymer membrane device of the said membrane units is a membrane selected from the group consisting of cellulose acetate, cellulose triacetate, polyimide, polyamide, polysulfone, and multi-layer composite.

12 . A process according to claim 8 further comprising the step of routing a portion of the permeate flow exiting the primary membrane unit and a permeate flow exiting the secondary membrane unit to a thermal oxidizer.

13 . A system according to claim 9 further comprising the step of routing a portion of the non-permeate flow exiting the secondary membrane unit to a low fuel gas system.

Assignees

• Cameron Solutions Inc

Inventors

• Peters Richard D

Classifications

• C10L2290/46

  Compressors or pumps · CPC title

• B01D63/04

  comprising multiple hollow fibre assemblies · CPC title

• C10L2290/10

  Recycling of a stream within the process or apparatus to reuse elsewhere therein · CPC title

• C10L2290/548

  Membrane- or permeation-treatment for separating fractions, components or impurities during preparation or upgrading of a fuel · CPC title

• C10L2290/562

  Modular or modular elements containing apparatus · CPC title