Patent DE725877C successfully refreshed from Google Patents.
Patent US3630672A successfully refreshed from Google Patents.
US3630672A
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US
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Use of potassium polyphosphate in so{11 {0 recovery from stack gases
Assignee: Tennessee Valley Authority
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Filing: 1969-03-14
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Granted: 1971-12-28
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Expires: 1989-03-14
Abstract
Abstract Recovery of sulfur dioxide from stack gas consisting of scrubbing the gas with potassium polyphosphate solution to form a slurry of crystallized potassium pyrosulfite. The potassium pyrosulfite is regenerated for further pickup of sulfur dioxide by (1) heating the slurry directly, (2) separating the potassium pyrosulfite and treating it in a reflux stripper, (3) heating the potassium pyrosulfite in solid form, or (4) heating solid potassium pyrosulfite to drive off one-third of the sulfur dioxide and reducing the remaining two-thirds to form hydrogen sulfide, the sulfur dioxide and hydrogen sulfide being reacted to form elemental sulfur.
Inventors
- 👤 John M Potts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 22:44
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/507; C; C01; C01B; C01B17/00; C01B17/48; C01B17/50; C01B17/60
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
13 words
maintaining the temperature in said stack gas scrubber means at about 125* F.;
Claim 2
Dependent Claim
19 words
The process of claim 1 wherein the temperature in said gas stripper means is maintained at about 248* F.
Claim 3
Dependent Claim
37 words
separating the resulting slurry formed in said stack gas scrubber means into a solids portion and a liquids portion, said solids portion comprising precipitated potassium pyrosulfite and said liquids portion comprising unreacted potassium pyrophosphate and potassium monoorthophosphate;
Claim 4
Dependent Claim
59 words
separating from the slurry formed in said gas scrubber means as the solid portions thereof the potassium pyrosulfite and returning the liquid portion of said slurry containing unreacted potassium pyrophosphate and potassium monoorthophosphate to said stack gas scrubber means for contact with additional SO2 in said stack gases introduced thereinto, along with potassium sulfite formed in step (3) infra;
Claim 5
Dependent Claim
13 words
maintaining the temperature in said stack gas scrubber means at about 125* F.;
Claim 6
Dependent Claim
59 words
heating said solid potassium pyrosulfite recovered from said stack gas scrubber means to form potassium sulfite and vapors of SO2 without forming any substantial amounts of potassium sulfate by introducing same into furnace means wherein is maintained a vacuum of about 25 inches of mercury and a temperature in the range from about 450* to about 550* F.; and
Claim 7
Dependent Claim
57 words
removing from said stack gas scrubber means the resulting slurry containing precipitated potassium pyrosulfite and introducing said resulting slurry into a gas stripper means, while maintaining the temperature therein in the range from about 230* F. to about 250* F. thereby effecting the decomposition of the potassium pyrosulfite therein to potassium sulfite and vapors of sulfur dioxide;
Claim 8
Dependent Claim
32 words
recycling said liquids portion together with potassium carbonate formed in step (6) infra back to said stack gas scrubber means for contact with additional SO2 contained in said stack gases introduced therein;
Claim 9
Dependent Claim
47 words
A process for efficiently and economically recovering the sulfur values from the stack gases of fossil fuel fed powerplants and the like, said stack gases containing substantial amounts of fly ash, dust, moisture, and only nominal amounts of sulfur values as SO2 which comprises the steps of
Claim 10
Dependent Claim
14 words
removing from said stack gas scrubber means the resulting slurry containing precipitated potassium pyrosulfite;
Claim 11
Dependent Claim
50 words
separating the precipitated potassium pyrosulfite from said slurry and recycling the liquid fractions of said slurry containing potassium pyrophosphate and potassium monoorthophosphate back to said stack gas scrubbing means for contact with additional sulfur dioxide in said stack gases introduced thereinto, together with potassium sulfite formed in step (6) infra;
Claim 12
Dependent Claim
13 words
recovering from said gas stripper means the sulfur dioxide vapor as product, and
Claim 13
Dependent Claim
11 words
recovering from said furnace means as product the resulting SO2 vapors.
Claim 14
Dependent Claim
32 words
The process of claim 3 wherein the materials in said gas stripping means are maintained under a vacuum of about 5-10 inches of mercury and at a temperature of about 190*-210* F.
Claim 15
Dependent Claim
65 words
heating in a first furnace means said solids portion recovered from said slurry formed in said stack gas scrubber means at atmospheric pressure and in the range from about 350* to about 450* F. to convert one-third of the sulfur values therein to sulfur dioxide without any appreciable formation of potassium sulfate therein, and withdrawing said sulfur dioxide and introducing same into step (7) infra;
Claim 16
Dependent Claim
87 words
introducing the residue formed in said first furnace means comprising undecomposed potassium pyrosulfite and potassium sulfite into a first section of a second furnace means, together with a reducing material, said reducing material selected from the group consisting of carbon, coal, coke, petroleum, carbon monoxide, hydrogen, and mixtures thereof, heating the constituents in said first section of said second furnace means, at atmospheric pressure, to a temperature range of about 900* to about 1,500* F. resulting in the formation of potassium sulfide, hydrogen sulfide, and carbon dioxide;
Claim 17
Dependent Claim
18 words
The process of claim 4 wherein the temperature maintained in said gas stripper means is about 200* F.
Claim 18
Dependent Claim
37 words
recycling the unreacted potassium pyrophosphate, potassium monoorthophosphate, together with the resulting potassium sulfite in said gas stripper means back to said gas scrubber means for contact with additional sulfur dioxide in said stack gases continuously introduced therein.
Claim 19
Dependent Claim
22 words
introducing said separated precipitated potassium pyrosulfite, together with 10 moles of water for each mole of said potassium pyrosulfite into gas-stripping means;
Claim 20
Dependent Claim
34 words
maintaining the materials in said gas-stripping means at atmospheric pressure and at a temperature of about 212* F. to effect the decomposition of said potassium pyrosulfite to potassium sulfite, sulfur dioxide, and water; and
Claim 21
Dependent Claim
48 words
A process for efficiently and econoMically recovering the sulfur values from the stack gases of fossil fuel fed power plants and the like, said stack gases containing substantial amounts of fly ash, dust, moisture, and only nominal amounts of sulfur values as SO2, which comprises the steps of:
Claim 22
Dependent Claim
71 words
introducing said potassium sulfide, hydrogen sulfide, and carbon dioxide, together with water, into a second section of said second furnace means, and maintaining said materials at atmospheric pressure therein in the temperature range of about 750* to about 850* F. to effect the fOrmation of potassium carbonate, along with vapors of hydrogen sulfide and carbon dioxide, said potassium carbonate recycled to said gas scrubber means as recited in step (4) supra;
Claim 23
Dependent Claim
73 words
subsequently introducing hydrogen sulfide and carbon dioxide formed in step (6) supra, together with sulfur dioxide formed in step (4) supra into a third furnace means, maintaining said materials in said third furnace means in the temperature range from about 400* to about 700* F., thereby effecting the formation of elemental sulfur together with vapors of water and carbon dioxide, and recovering from said third furnace means as product said elemental sulfur; and
Claim 24
Dependent Claim
13 words
recovering from said gas stripping means as product the resulting sulfur dioxide vapors.
Claim 25
Dependent Claim
17 words
The process of claim 6 wherein the temperature maintained in said furnace means is about 500* F.
Claim 26
Dependent Claim
47 words
A process for efficiently and economically recovering the sulfur values from the stack gases of fossil fuel power plants and the like, said stack gases containing substantial amounts of fly ash, dust, moisture and only nominal amounts of sulfur values as SO2, which comprises the steps of
Claim 27
Dependent Claim
44 words
recycling said potassium carbonate formed in step (6) supra, together with the liquids fraction residue comprising potassium pyrophosphate and potassium monoorthophosphate from step (1) supra to said stack gas scrubber means for contact with additional sulfur dioxide vapors from said stack gases fed thereinto.
Claim 28
Dependent Claim
24 words
The process of claim 8 wherein the temperature in the first section of said second furnace means is maintained at about 1, 400* F.
Claim 29
Dependent Claim
23 words
The process of claim 8 wherein the temperature in said second section of said second furnace means is maintained at about 800* F.
Claim 30
Dependent Claim
121 words
In the recovery of sulfur values from fossil fuel fed powerplant stack gases and the like wherein said stack gas containing only nominal amounts of sulfur values as SO2 are contacted with an aqueous potassium phosphate scrubbing solution followed by regeneration of the resulting scrubber effluent to yield a rich stream of SO2 eminently suitable for the recovery of the said sulfur values, the improvement wherein said scrubbing solution contains at least one-third by weight of potassium pyrophosphate and which, after absorbing the SO2 values from the stack gas, immediately showers out said SO2 values as potassium pyrosulfite, thereby eliminating recirculating dissolved SO2 to said stack gases whereby the undesirable oxidation of dissolved SO2 to the sulfate form is substantially eliminated.
Claim 31
Dependent Claim
54 words
An improved process according to claim 11 wherein said potassium phosphate solution, in addition to containing about one-third of its potassium values as potassium pyrophosphate, contains about 5 to about 10 percent of its potassium values as potassium tripolyphosphates and in amounts up to about 2 percent of its potassium values of potassium tetrapolyphosphate.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-12-27 | 1975-06-28 | 1975-12-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-27 | 1979-06-28 | 1979-12-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-27 | 1983-06-28 | 1983-12-28 | $7700.00 | Window Closed / Lapsed |