US4091075A
Expired / Lapsed
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Method for removing sulfur dioxide from flue gases
Assignee: AEL Industries Inc
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Filing: 1976-04-19
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Granted: 1978-05-23
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Expires: 1996-04-19
Abstract
Abstract In a "first" scrubbing operation, the sulfur dioxide containing flue gas is scrubbed with an aqueous solution containing ferric sulfate and aluminum sulfate. The ferric sulfate oxidizes the sulfur dioxide to sulfuric acid, which dissolves in the solution, and is reduced to ferrous sulfate. In a subsequent "second" scrubbing operation, the solution, now containing ferrous sulfate, aluminum sulfate, and sulfuric acid, is scrubbed with air. This regenerates, or re-oxidizes the ferrous sulfate to ferric sulfate. The presence of aluminum sulfate accelerates the rate of regeneration. The regenerated solution is then returned to its function in a "first" scrubbing operation, and the indicated cycle of "first" and "second" scrubbing operations are repeated.
Inventors
- 👤 Leopold Pessel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 09:22
CPC Classifications
C; C05; C05C; C05C9/00; B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/507; C01; C01B; C01B17/00; C01B17/69; C01B17/74
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
139 words
A method of removing sulfur dioxide from flue gas comprising the steps of: (a) subjecting the sulfur dioxide containing flue gas to an aqueous composition containing a compound of iron capable of providing ferric ions in excess of 0.6 weight percent and in which the iron ion can be reduced by sulfur dioxide from a higher valence state to a lower valence state and thereby oxidize the sulfur dioxide to sulfuric acid, and an aluminum compound capable of providing aluminum ions in an amount of not less than 0.05 weight percent, and (b) subjecting the aqueous composition containing said iron compound in its lower valence state to the action of oxygen to reoxidize the reduced iron salt to its higher valence state and thereby regenerate the aqueous composition for use in removing additional sulfur dioxide from the flue gas.
Claim 2
Independent Claim
139 words
A method of removing sulfur dioxide from flue gas comprising the steps of: (a) subjecting the sulfur dioxide containing flue gas to an aqueous composition containing a compound of iron capable of providing ferric ions in excess of 0.6 weight percent and in which the iron ion can be reduced by sulfur dioxide from a higher valence state to a lower valence state and thereby oxidize the sulfur dioxide to sulfuric acid, and an aluminum compound capable of providing aluminum ions in an amount of not less than 0.05 weight percent, and (b) subjecting the aqueous composition containing said iron compound in its lower valence state to the action of oxygen to reoxidize the reduced iron salt to its higher valence state and thereby regenerate the aqueous composition for use in removing additional sulfur dioxide from the flue gas.
Claim 3
Dependent Claim
22 words
The method in accordance with claim 1 in which the aluminum compound is a salt of aluminum to provide the aluminum ions.
Claim 4
Dependent Claim
15 words
The method in accordance with claim 1 in which the aluminum compound is aluminum sulfate.
Claim 5
Dependent Claim
20 words
The method in accordance with claim 3 in which the composition contains at least 1.12% by weight of aluminum sulfate.
Claim 6
Dependent Claim
27 words
The method in accordance with claim 1 in which the aqueous composition to which the flue gas is subjected is at least slightly acidic with sulfuric acid.
Claim 7
Dependent Claim
22 words
The method in accordance with claim 1 in which the iron compound is ferric sulfate, and the aluminum compound is aluminum sulfate.
Claim 8
Dependent Claim
76 words
The method in accordance with claim 1 in which the amount of iron ions present in the aqueous mixture is not less than 1 percent by weight and the aluminum compound is in a proportion of not less than 10 weight percent with respect to the weight of the iron compound, said proportion being based upon the ratio of the equivalent Al 2 O 3 to the equivalent Fe 2 O 3 derived from the compounds.
Claim 9
Dependent Claim
65 words
The method in accordance with claim 1 in which the iron compound provides iron ions in the aqueous mixture in excess of 1 percent by weight, and the aluminum compound is present in a weight percentage greater than that of the iron compound based upon the ratio of the equivalent Al 2 O 3 to the equivalent Fe 2 O 3 derived from the compounds.
Claim 10
Dependent Claim
33 words
The method in accordance with claim 6 in which the amount of aluminum ions present in the aqueous composition corresponds to the solution saturation limit of the aluminum compound in the aqueous composition.
Claim 11
Dependent Claim
33 words
The method in accordance with claim 6 in which the amount of iron ions present in the aqueous composition corresponds to the solution saturation limit of the iron compound in the aqueous composition.
Claim 12
Dependent Claim
37 words
The method in accordance with claim 6 in which the amount of aluminum compound present in the aqueous composition is greater than that corresponding to the solution saturation limit of the aluminum compound in the aqueous composition.
Claim 13
Dependent Claim
37 words
The method in accordance with claim 6 in which the amount of iron compound present in the aqueous composition is greater than that corresponding to the solution saturation limit of the iron compound in the aqueous composition.
Claim 14
Dependent Claim
31 words
The method in accordance with claim 6 in which the aqueous composition is subjected to the flue gas until a predetermined amount but not all of the iron compound is reduced.
Claim 15
Dependent Claim
29 words
The method in accordance with claim 13 in which the aqueous composition is subjected to the flue gas until about 90 weight percent of the iron compound is reduced.
Claim 16
Dependent Claim
29 words
The method in accordance with claim 13 in which the aqueous composition is subjected to the flue gas until about 50 weight percent of the iron compound is reduced.
Claim 17
Dependent Claim
60 words
The method in accordance with claim 6 in which the composition containing iron sulfate and aluminum sulfate is passed through a flue gas scrubber, and subsequently the composition containing the reduced iron compound is passed from the flue gas scrubber to a regeneration scrubber and air is passed through the regeneration scrubber to reoxidize the iron compound in the composition.
Claim 18
Dependent Claim
27 words
The method in accordance with claim 16 in which the aqueous composition to which the flue gas is subjected is at least slightly acidic with sulfuric acid.
Claim 19
Dependent Claim
35 words
The method in accordance with claim 16 in which the composition in the flue gas scrubber is subjected to the flue gas until a predetermined amount but not all of the iron salt is reduced.
Claim 20
Dependent Claim
29 words
The method in accordance with claim 18 in which the aqueous composition is subjected to the flue gas until about 90 weight percent of the iron salt is reduced.
Claim 21
Dependent Claim
29 words
The method in accordance with claim 18 in which the aqueous composition is subjected to the flue gas until about 50 weight percent of the iron salt is reduced.
Claim 22
Dependent Claim
32 words
The method in accordance with claim 16 in which the composition is repeatedly cycled between the flue gas scrubber and the regeneration scrubber to produce a progessively increasing content of sulfuric acid.
Claim 23
Dependent Claim
38 words
The method in accordance with claim 6 in which the gases after being subjected to the iron salt mixture are passed through an aqueous solution of a nitrogen compound selected from the group consisting of urea and guanidine.
Claim 24
Dependent Claim
40 words
The method in accordance with claim 16 in which the gases which leave the flue gas scrubber are passed through a third scrubber containing an aqueous solution of a nitrogen compound selected from the group consisting of urea and quanidine.
Claim 25
Dependent Claim
44 words
The method in accordance with claim 16 in which the gases which leave the flue gas scrubber and the regeneration scrubber are passed through a third scrubber containing an aqueous solution of a nitrogen compound selected from the group consisting of urea and guanidine.
Claim 26
Dependent Claim
30 words
The method in accordance with claim 22 in which the composition is repeatedly cycled between flue gas scrubber and air scrubber to produce a progressively increasing content of sulfuric acid.
Claim 27
Dependent Claim
37 words
The method in accordance with claim 21 in which the composition containing sulfuric acid is brought in contact with a material selected from a group comprising inorganic waste materials and mineral deposits to leach therefrom acid-soluble material.
Claim 28
Dependent Claim
19 words
A method in accordance with claim 26 in which the acid-soluble material is predominantly composed of oxydic aluminum compounds.
Claim 29
Dependent Claim
21 words
A method in accordance with claim 26 in which the composition is maintained at a temperature substantially above ambient room temperature.
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) | 1981-05-22 | 1981-11-21 | 1982-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-05-22 | 1985-11-21 | 1986-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-05-22 | 1989-11-21 | 1990-05-23 | $7700.00 | Window Closed / Lapsed |