US009919262B2  c12)  United States Patent  Ouimet et al.  (IO)  Patent No.:  US 9,919,262 B2  (45)  Date of Patent:  Mar.20,2018  (54)  PROCESS FOR CAPTURING SULFUR  DIOXIDE FROM A GAS STREAM  (71)  Applicant:  CANSOLV TECHNOLOGIES INC.,  Montreal, Quebec (CA)  (72)  Inventors:  Michel Ouimet,  Mirabel (CA);  Melina  Infantino,  Montreal (CA)  (73)  Assignee:  SHELL OIL COMPANY,  Houston,  TX (US)  ( *)  Notice:  Subject to any disclaimer, the term ofthis  patent is extended or adjusted under 35  U.S.C. 154(b) by 122 days.  (21)  Appl. No.:  15/034,360  (22)  PCT Filed:  Nov. 5, 2014  (86)  PCT No.:  PCT /CA2014/051059  § 371 (c)(l),  (2) Date:  May 4, 2016  (87)  PCT Pub. No.:  WO2015/066807  PCT Pub. Date:  May 14, 2015  (51)  Int. Cl.  (52)  U.S. Cl.  CPC .....  BOID 53/1481  (2013.01);  BOID 53/1425  (2013.01);  BOID 5311475  (2013.01);  (58)  Field of Classification Search  CPC ............ BOID 53/1425; BOID 53/1475; BOID  53/1481; BOID 53/1493; BOID 2252/20;  (65)  Prior Publication Data  (30)  Foreign Application Priority Data  15 Claims, 6 Drawing Sheets  (57)  ABSTRACT  OTHER PUBLICATIONS  FOREIGN PATENT DOCUMENTS  U.S. PATENT DOCUMENTS  (56)  References Cited  (Continued)  US 2016/0263519 Al  Sep. 15, 2016  Nov. 7, 2013  (EP) ..................................... 13191903  (Continued)  A process for removing sulfur dioxide from a feed gas  stream, which comprises (i) contacting the feed gas stream  with an aqueous lean absorbing medium comprising a  chemical solvent comprising a regenerable absorbent, a  physical solvent, and one or more heat stable salts. The  regenerable absorbent is an amine. The ratio of the wt % of  the physical solvent over that of the regenerable absorbent is  0.5 to 2.5. The ratio of the wt% of heat stable salts over that  of the regenerable absorbent is 0.29 to 0.37. The pH of the  lean absorbing medium is 6 or less. With the process SO2  can be selectively removed. When the absorbing medium is  stripped, a reduced amount of energy is required as com› pared to known processes.  Primary Examiner  - Frank Lawrence  (Continued)  Fogg, P.G.T., et al.: Solubility of Gases in Liquids, A Critical  Evaluation of Gas/Liquid Systems in Theory and Practice, Chapter  5, Solubility of Sulfur Diolide, pp. 39-85, 1991.  (Continued)  (Continued)  4,999,031 A  *  3/1991 Gerhardt .  5,019,361 A  5/1991 Hakka  B0lD 53/1462  423/229  CA  CA  2534879  2748214  2/2005  2/2013  BOID 53/14  BOID 53/50  (2006.01)  (2006.01)  240  340  250  220 