Sour gas and acid natural gas separation membrane process by pre removal of dissolved elemental sulfur for plugging prevention

• US 8,801,832 B2
• Filed: 02/12/2014
• Issued: 08/12/2014
• Est. Priority Date: 11/01/2010
• Status: Active Grant

• Current Assignee: Saudi Arabian Oil Company (Government of Saudi Arabia)
• Original Assignee: Saudi Arabian Oil Company (Government of Saudi Arabia)
• Inventors: Vaidya, Milind M., Ballaguet, Jean-Pierre R., Duval, Sebastien A., Khawajah, Anwar H.
• Primary Examiner(s): Smith, Duane
• Assistant Examiner(s): PATEL, PANKTI R
• Application Number:
  US14/178,936
• Publication Number:
  US 20140187838A1
• Time in Patent Office: 181 Days
• Field of Search: None
• US Class Current: 95/8
• CPC Class Codes: B01D 2256/245 Methane
• CPC Class Codes: B01D 2257/102 Nitrogen
• CPC Class Codes: B01D 2257/30 Sulfur compounds
• CPC Class Codes: B01D 2257/304 Hydrogen sulfide
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/80 Water
• CPC Class Codes: B01D 53/14 by absorption
• CPC Class Codes: B01D 53/229 Integrated processes (Diffusion and at least one other process, e.g. adsorption, absorption)
• CPC Class Codes: C07C 7/11 by absorption, i.e. purification or separation of gaseous hydrocarbons with the aid of liquids
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

Methods for removing sulfur from a gas stream prior to sending the gas stream to a gas separation membrane system are provided. Two schemes are available. When the sulfur content is high or flow is relatively high, a scheme including two columns where one tower is regenerated if the sulfur concentration exceeds a preset value can be used. When the sulfur content is low or flow is relatively low, a scheme including one column and an absorption bed.

Claims

1. A method of removing sulfur from a gas stream comprising the steps of:

a. cooling the gas stream to produce a gas stream without liquids and a chilled solvent;

b. contacting the gas stream without liquid with the chilled solvent to selectively absorb at least a portion of elemental sulfur from the gas stream;

c. contacting the chilled solvent with an absorbent bed or a filter to remove sulfur in excess of solubility;

d. analyzing a sulfur concentration in the gas stream without liquids to determine if the sulfur concentration exceeds a sulfur solubility estimated in retentate and permeate flows by a membrane separation process simulation; and

e. passing the gas stream without liquids through gas separation membranes.

2. The method of claim 1 where the absorbent bed contains activated carbon, supported metallic oxides, supported organic oxides, or combinations thereof.

3. The method of claim 1 where the filter contains supported metallic filters, supported organic filters, polymeric filters, or combinations thereof.

4. The method of claim 1 where the solvent is polyethylene glycol, ethers of polyethylene glycol, polypropylene glycol, ethers of propylene glycol, n-methylpyrolidone, n-ethyl pyrolidone, n-cyclohexyl pyrolidone, n-phenyl morpholine, n-cyclohexyl morpholine, dimethyl disulfur, dimethyl-sulfur, carbon disulfide, xylene, toluene, BTX (a mixture of benzene, toluene, and xylenes), kerosene, naphthalene, alkyl-naphthalene, or combinations thereof.

5. The method of claim 1 further including the step of separating a heavy hydrocarbon stream from the gas stream without liquids prior to passing the gas stream without liquids through gas separation membranes.