US3733779A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stripping of sulfur dioxide from gas streams by use of n-alkyl lactams
Assignee: GAF Chemicals Corp
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Filing: 1972-04-17
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Granted: 1973-05-22
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Expires: 1992-04-17
Abstract
Abstract Sulfur dioxide is stripped from a gas stream by N-alkyl lactam, particularly an N-lower alkyl pyrrolidone, e.g., N-methyl pyrrolidone, sufficiently to permit the non-polluting discharge of the gas stream to the atmosphere. Gas streams containing from about 0.05 percent to about 10 percent sulfur dioxide by volume can thus be passed at a gas mass flow velocity of 200-3,000 lbs/hr/ft2 through an N-alkyl lactam-containing contacting zone of 5-85 ft in length, to reduce the sulfur dioxide content thereof to less than about 250 ppm, advantageously to less than 100 ppm, or even 50 ppm, prior to discharge to the atmosphere. Gas streams having SO2 contents of from about 0.01 percent to about 50 percent by volume can thus be treated to achieve at least about 90 percent SO2 removal by volume, desirably at least about 95 percent, and advantageously at least about 98 percent removal. Gas temperatures of about 0*-75*C, preferably about 35*65*C, are employed. Lactam entrained in the gas stream discharged from the contacting zone is conveniently recovered in a water scrubbing zone. Lactam from the contacting zone and lactam in water removed from the scrubbing zone can conveniently be recovered in a distillation zone by heating to 100*-200*C. The lactam recovered can be recycled to the contacting zone, and the SO2 stripped from said lactam can be conveniently recovered for non-polluting disposal or use.
Inventors
- 👤 A Bellisio
- 👤 H Psyras
- 👤 M Fein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 01:12
CPC Classifications
C; C01; C01B; C01B17/00; C01B17/48; C01B17/50; C01B17/60; B; B01; B01D; B01D53/00; B01D53/14; B01D53/1418; B01D53/1425; B01D53/1456; B01D53/1481; B01D53/1493; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/507; Y; Y02; Y02A; Y02A50/00; Y02A50/20
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
22 words
The process of claim 1 in which said sulfur dioxide impurities in the discharged gas stream comprise less than about 100 ppm.
Claim 2
Dependent Claim
26 words
The process of claim 2 in which said sulfur dioxide impurity concentration in the discharged gas stream is from about 50 ppm to about 100 ppm.
Claim 3
Dependent Claim
26 words
The process of claim 2 in which said sulfur dioxide impurity concentration in the discharged gas stream is from about 5 ppm to about 50 ppm.
Claim 4
Dependent Claim
17 words
The process of claim 1 in which said gas temperature is from about 35*C to about 65*C.
Claim 5
Dependent Claim
27 words
The process of claim 5 in which the sulfur dioxide content of the untreated gas stream is from about 0.1 percent to about 8 percent by volume.
Claim 6
Dependent Claim
27 words
The process of claim 6 in which said sulfur dioxide content of the untreated gas stream is from about 0.1 percent to about 0.5 percent by volume.
Claim 7
Dependent Claim
22 words
The process of claim 7 in which the sulfur dioxide impurities in the discharged gas stream comprise less than about 100 ppm.
Claim 8
Dependent Claim
19 words
The process of claIm 6 in which said contacting zone has a length of at least about 10 ft.
Claim 9
Dependent Claim
12 words
The process of claim 5 in which said lactam is N-methyl pyrrolidone.
Claim 10
Dependent Claim
12 words
The process of claim 5 in which said lactam is N-cyclohexyl pyrrolidone.
Claim 11
Dependent Claim
15 words
The process of claim 5 in which said liquid lactam comprises an aqueous solution thereof.
Claim 12
Dependent Claim
22 words
The process of claim 12 in which said aqueous solution contains from about 2 percent to about 25 percent water by weight.
Claim 13
Dependent Claim
25 words
The process of claim 13 in which said water content is from about 15 percent to about 25 percent by weight of said lactam solution.
Claim 14
Dependent Claim
21 words
The process of claim 13 in which said water content is from about 2 percent to about 10 percent by weight.
Claim 15
Dependent Claim
53 words
The process of claim 5 in which the sulfur dioxide content of the untreated gas stream is from about 0.1 percent to about 8 percent by volume, the sulfur dioxide impurities in the discharged gas stream comprising less than about 100 ppm, said contacting zone being at least about 10 ft. in length.
Claim 16
Dependent Claim
13 words
The process of claim 16 in which said N-alkyl lactam comprises N-methyl pyrrolidone.
Claim 17
Dependent Claim
76 words
The process of claim 1 and including removing the N-alkyl lactam having sulfur dioxide absorbed therein from the contacting zone and heating to from about 100*C to about 200*C to strip said sulfur-dioxide-containing gases therefrom and thereafter recycling said N-alkyl lactam to said contacting zone for contact with additional quantities of said sulfur dioxide contaminated gas stream, the stripped sulfur dioxide gases being utilized in the production of sulfur-containing compounds for subsequent use or non-polluting disposal.
Claim 18
Dependent Claim
14 words
The process of claim 18 in which said lactam is an N-lower alkyl pyrrolidone.
Claim 19
Dependent Claim
12 words
The process of claim 19 in which said lactam comprises N-methyl pyrrolidone.
Claim 20
Dependent Claim
17 words
The process of claim 20 in which said gas temperature is from about 35*C to about 65*C.
Claim 21
Dependent Claim
54 words
The process of claim 21 in which said sulfur dioxide-contaminated gas stream is at an elevated temperature above about 65*C and including cooling said gas stream to from about 35*C to about 65*C prior to contact thereof with said liquid lactam, said gas mass flow velocity being from about 1,000 to about 2,000 lbs/hr/ft2.
Claim 22
Dependent Claim
58 words
The process of claim 22 in which the sulfur dioxide concentration in the treated gas stream discharged to the atmosphere is from about 50 ppm to about 100 ppm, said contacting zone being at least about 20 ft. in length, said lactam comprising an aqueous solution thereof containing up to about 25 percent water by weight of solution.
Claim 23
Dependent Claim
28 words
The process of claim 23 in which said lactam comprises an aqueous solution thereof containing from about 2 percent to about 10 percent water by weight of solution.
Claim 24
Dependent Claim
186 words
A process for treating a gas stream containing sulfur dioxide impurities comprising: a. contacting an incoming gas stream containing from about 0.01 percent to about 50 percent sulfur dioxide by volume with a liquid N-alkyl lactam solvent in a contacting zone at a gas temperature of from about 0*C to about 75*C at a pressure assuring the flow of said gas stream through the contacting zone at a gas mass flow velocity of from about 200 to about 3, 000 lbs/hr/ft2, the contacting zone having a length of from about 5 ft. to about 85 ft.; and b. discharging the thus-treated gas stream from the contacting zone, said stream having a sulfur dioxide content of not more than about 10 percent by volume of the sulfur dioxide content of the untreated gas stream, at least about 90 percent by volume of said sulfur dioxide impurities of the untreated gas stream being removed therefrom by absorption in said N-alkyl lactam, whereby the sulfur dioxide impurities are very substantially washed from The gas stream containing same, the sulfur dioxide impurities being conveniently available for non-polluting disposal or use.
Claim 25
Dependent Claim
40 words
The process of claim 25 in which at least about 95 percent of the sulfur dioxide impurities are removed from the incoming gas stream by absorption in said N-alkyl lactam, said gas temperature being from about 35*C to about 65*C.
Claim 26
Dependent Claim
30 words
The process of claim 26 in which at least about 98 percent of the sulfur dioxide impurities are removed from the incoming gas stream by absorption in said N-alkyl lactam.
Claim 27
Dependent Claim
60 words
The process of claim 25 in which said sulfur dioxide content of the untreated gas stream is from about 0.1 percent to about 0.5 percent by volume, at least about 95 percent of the sulfur dioxide impurities being removed from the incoming gas stream by absorption in said N-alkyl lactam, said gas temperature being from about 35*C to about 65*C.
Claim 28
Dependent Claim
21 words
The process of claim 28 in which said lactam comprises N-methyl pyrrolidone containing up to about 25 percent water by weight.
Claim 29
Dependent Claim
22 words
The process of claim 29 in which said aqueous solution contains from about 2 percent to about 10 percent water by weight.
Claim 30
Dependent Claim
100 words
The process of claim 25 in which said sulfur dioxide-containing gas stream is at a temperature above about 65*C and including cooling said gas stream to from about 35*C to about 65*C prior to contact thereof with said liquid lactam and including heating lactam removed from the contacting zone to from about 100*C to about 200*C to strip said sulfur dioxide-containing gases therefrom and thereafter recycling said N-alkyl lactam to said contacting zone for contact with additional quantities of said sulfur dioxide contaminated gas stream, the stripped sulfur dioxide gases being thereafter compressed and recovered for non-polluting disposal or use.
Claim 31
Dependent Claim
19 words
The process of claim 31 in which said contacting zone has a length of at least about 20 ft.
Claim 32
Dependent Claim
12 words
The process of claim 32 in which said lactam comprises N-cyclohexyl pyrrolidone.
Claim 33
Dependent Claim
33 words
The process of claim 32 in which said lactam comprises N-methyl pyrrolidone, said lactam removing at least about 95 percent by volume of the sulfur dioxide impurities contained in the incoming gas stream.
Claim 34
Dependent Claim
39 words
The process of claim 34 in which said lactam removes at least about 98 percent by volume of the sulfur dioxide impurities contained in the incoming gas stream, said absorption zone being at least about 40 ft. in length.
Claim 35
Dependent Claim
20 words
The process of claim 35 in which said gas mass flow velocity is from about 1,000 to about 2,000 lbs/hr/ft2.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |