US3907523A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for removing SO{HD 2 {B from gases
Assignee: FLSmidth Inc
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Filing: 1974-08-21
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Granted: 1975-09-23
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Expires: 1994-08-21
Abstract
Abstract Process for removing contaminants (particularly SO2 gas) from industrial waste gases such as are produced by the burning of sulfur containing fossil fuels or in smelting operations. The process uses a multistage scrubber with each stage separately supplied with lime slurry controlled as to pH for optimum efficiency.
Inventors
- 👤 Jr Deering D Melin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 04:58
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/501
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
138 words
IN A SCRUBBING PROCESS FOR REMOVING SULFUR DIOXIDE FROM WASTE GASES, THE PROCESS MAKING USE OF A SCRUBBER HAVING A PLURALITY OF SCRUBBER STAGES THROUGH WHICH THE GAS IS DIRECTED WITH EACH STAGE HAVING SEPARATE MEANS FOR INTRODUCING AND FOR REMOVING LIQUID SCRUBBING MEDIUM, THE STEPS COMPRISING PASSING THE SULFUR DIOXIDE CONTAINING WASTE GASES SEQUENTIALLY THROUGH EACH OF SAID STEPS, CONTINUOUSLY AND SEPARATELY SUPPLYING EACH STAGE WITH A MILK OF LIME SLURRY AAS A SCRUBBING MEDIUM, THE SLURRY FOR EACH STAGE BEING SUPPLIED FROM AN INDEPENDENT MIX-DELAY TANK FOR EACH STAGE, SUPPLYING EACH OF SAID MIX-DELAY TANKS LIME SLURRY REMOVED FROM SAID STAGES, AND SUPPLYING FRESH MAKE UP SLURRY TO WEACH OF SAID MIX-DELAY TANKS IN SUCH CONTROLLED AMOUNTS AS TO MAINTAIN THE PH OF THE SLURRY REMOVED FROM EACH SCRUBBER WITHIN THE RANGE OF 5.5 TO 6.0.
Claim 2
Dependent Claim
138 words
IN A SCRUBBING PROCESS FOR REMOVING SULFUR DIOXIDE FROM WASTE GASES, THE PROCESS MAKING USE OF A SCRUBBER HAVING A PLURALITY OF SCRUBBER STAGES THROUGH WHICH THE GAS IS DIRECTED WITH EACH STAGE HAVING SEPARATE MEANS FOR INTRODUCING AND FOR REMOVING LIQUID SCRUBBING MEDIUM, THE STEPS COMPRISING PASSING THE SULFUR DIOXIDE CONTAINING WASTE GASES SEQUENTIALLY THROUGH EACH OF SAID STEPS, CONTINUOUSLY AND SEPARATELY SUPPLYING EACH STAGE WITH A MILK OF LIME SLURRY AAS A SCRUBBING MEDIUM, THE SLURRY FOR EACH STAGE BEING SUPPLIED FROM AN INDEPENDENT MIX-DELAY TANK FOR EACH STAGE, SUPPLYING EACH OF SAID MIX-DELAY TANKS LIME SLURRY REMOVED FROM SAID STAGES, AND SUPPLYING FRESH MAKE UP SLURRY TO WEACH OF SAID MIX-DELAY TANKS IN SUCH CONTROLLED AMOUNTS AS TO MAINTAIN THE PH OF THE SLURRY REMOVED FROM EACH SCRUBBER WITHIN THE RANGE OF 5.5 TO 6.0.
Claim 3
Dependent Claim
16 words
A process as in claim 1 in which the pH range is about 5.5 to 5.6.
Claim 4
Dependent Claim
56 words
A process as in claim 1 in which the waste gas is directed through a scrubbing stage following the aforesaid scrubbing stage, and in which the excess slurry from all of the holding tanks is subjected to a thickening operation, and the overflow from the thickening operation used to supply scrubbing medium for said additional stage.
Claim 5
Dependent Claim
33 words
A process as in claim 3 in which the slurry supplied to said additional stage is controlled with respect to its pH, whereby the pH value of the same is maintained substantially constant.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |