US3914387A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of removing sulfur dioxide from a dust containing exhaust gas stream
Assignee: GEA Group AG
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Filing: 1974-01-14
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Granted: 1975-10-21
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Expires: 1994-01-14
Abstract
Abstract A method of removing sulfur dioxide (SO2) from a dust-containing exhaust gas, especially waste gas from a metallurgical process, wherein the exhaust gas is treated with an aqueous solution of sodium hydroxide (NaOH) and disodium sulfate (Na2SO4) so that a major part of the SO2 is reacted with the solution to form Na2SO4 in the presence of catalytically effective quantities of iron, cobalt, nickel, manganese or vanadium or compounds thereof intrinsically present in the gas stream as impurities or added thereto to catalyze the reaction. A portion of the solution is directly recycled into the scrubber while a second portion, continuously withdrawn from the scrubber, is treated with calcium hydroxide (Ca(OH)2) to precipitate calcium sulfate (CaSO4) and form NaOH in the supernatant liquid. The latter is recycled to the scrubber and the rate at which NaOH is returned from the second portion to the scrubber is approximately equal to the rate at which the NaOH is consumed in the scrubber by reaction with SO2.
Inventors
- 👤 Jordan Wenzel Von
- 👤 Hans-Jorg Barth
- 👤 Hans Koch
- 👤 Gunter Boning
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 07:06
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/501; B01D53/74; B01D53/86; B01D53/8603; B01D53/8609
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
221 words
A PROCESS FOR REMOVING SULFUR DIOXIDE FROM A DUST-CONTAINING GAS STREAM COMPRISING THE STEPS OF: A. SCRUBBING SAID DUST-CONTAINING GAS STREAM WITH AN AQUEOUS SOLUTION OF SODIUM HYDROXIDE AND SODIUM SULFATE DRAWN FROM A SOLUTION RESEVIOR IN THE PRESENCE OF A CATALYST CONTAINING MATERIAL SELECTED FROM THE GROUP CONSISTING OF IRON, COBALT, NICKEL, MANGANESE AND VANADIUM, SAID CATALYST BEING CAPABLE OF PROMOTING THE SUBSTANTIALLY COMPLETE COVERSION OF THE SULFUR DIOSIDE OF SAID GAS STREAM WITH THE SODIUM HYDROXIDE OF SAID SOLUTION INTO SODIUM SULFATE, B. CONTINUOUSLY WITHDRAWING THE SOLUTION LADEN WITH SODIUM SULFATE FROM STEP (A), MEASURING ITS PH VALUE AND FEEDING IT TO A SETTLING ZONE AND PRODUCING A SUPERNATANT LIQUID THEREIN, C. FEEDING A FRIST PARTIAL STREAM OF SUPERNATANT LIQUID FROM SAID SETTLING ZONE TO SAID SOLUTION RESERVOIR, D. FEEDING A SECOND PARTIAL STREAM OF SAID SUPERNATANT LIQUID FROM SAID SETTLING ZONE TO A PRECIPITATION ZONE AND MIXING SAID SECOND PRATIAL STREAM WITH CALCIUM HYDROXIDE TO PRECIPITATE CALCIUM SULFATE THEREFROM AND FORM A SECOND SUPERNATANT LIQUID CONTAINING SODIUM HYDROXIDE, AND WITHDRAWING CALCIUM SULFATE FROM SAID PRECIPITATION ZONE, E. FEEDING SAID SECOND SUPERNATANT LIQUID FROM SAID PRECIPITATION ZONE TO SAID SOLUTION RESERVOIR AND ADJUSTING THE AMOUNT OF SAID SECOND SUPERNATANT LIQUID TO KEEP THE PH VALUE OF THE LADEN SOLUTION OF STEP (B) IN THE RANGE OF 6.5 TO 7.
Claim 2
Dependent Claim
221 words
A PROCESS FOR REMOVING SULFUR DIOXIDE FROM A DUST-CONTAINING GAS STREAM COMPRISING THE STEPS OF: A. SCRUBBING SAID DUST-CONTAINING GAS STREAM WITH AN AQUEOUS SOLUTION OF SODIUM HYDROXIDE AND SODIUM SULFATE DRAWN FROM A SOLUTION RESEVIOR IN THE PRESENCE OF A CATALYST CONTAINING MATERIAL SELECTED FROM THE GROUP CONSISTING OF IRON, COBALT, NICKEL, MANGANESE AND VANADIUM, SAID CATALYST BEING CAPABLE OF PROMOTING THE SUBSTANTIALLY COMPLETE COVERSION OF THE SULFUR DIOSIDE OF SAID GAS STREAM WITH THE SODIUM HYDROXIDE OF SAID SOLUTION INTO SODIUM SULFATE, B. CONTINUOUSLY WITHDRAWING THE SOLUTION LADEN WITH SODIUM SULFATE FROM STEP (A), MEASURING ITS PH VALUE AND FEEDING IT TO A SETTLING ZONE AND PRODUCING A SUPERNATANT LIQUID THEREIN, C. FEEDING A FRIST PARTIAL STREAM OF SUPERNATANT LIQUID FROM SAID SETTLING ZONE TO SAID SOLUTION RESERVOIR, D. FEEDING A SECOND PARTIAL STREAM OF SAID SUPERNATANT LIQUID FROM SAID SETTLING ZONE TO A PRECIPITATION ZONE AND MIXING SAID SECOND PRATIAL STREAM WITH CALCIUM HYDROXIDE TO PRECIPITATE CALCIUM SULFATE THEREFROM AND FORM A SECOND SUPERNATANT LIQUID CONTAINING SODIUM HYDROXIDE, AND WITHDRAWING CALCIUM SULFATE FROM SAID PRECIPITATION ZONE, E. FEEDING SAID SECOND SUPERNATANT LIQUID FROM SAID PRECIPITATION ZONE TO SAID SOLUTION RESERVOIR AND ADJUSTING THE AMOUNT OF SAID SECOND SUPERNATANT LIQUID TO KEEP THE PH VALUE OF THE LADEN SOLUTION OF STEP (B) IN THE RANGE OF 6.5 TO 7.
Claim 3
Dependent Claim
35 words
The process defined in claim 1 wherein said catalyst is added to said aqueous solution of sodium hydroxide and sodium sulfate prior to its use in step (a) for the scrubbing of said dust-containing gas.
Claim 4
Dependent Claim
34 words
The process defined in claim 1 wherein said catalyst is added to said dust-containing gas stream prior to the scrubbing thereof with said aqueous solution of sodium hydroxide and sodium sulfate in step (a).
Claim 5
Dependent Claim
32 words
The process defined in claim 1 wherein said catalyst is added during the scrubbing of said dust-containing gas stream with said aqueous solution of sodium hydroxide and sodium sulfate in step (a).
Claim 6
Dependent Claim
24 words
The process defined in claim 1 wherein said catalyst is present originally as dust in said gas stream prior to scrubbing in step (a).
Claim 7
Dependent Claim
23 words
The process defined in claim 1 wherein the scrubbing is carried out in step (a) in a plurality of scrubbing stages in series.
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) | 1978-10-20 | 1979-04-21 | 1979-10-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-20 | 1983-04-21 | 1983-10-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-20 | 1987-04-21 | 1987-10-21 | $7700.00 | Window Closed / Lapsed |