US3870781A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Air pollution control system
Assignee: Combustion Engineering Inc
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Filing: 1972-07-27
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Granted: 1975-03-11
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Expires: 1992-07-27
Abstract
Abstract An air pollution control system for treating the flue gases from a fossil fuel fired furnace scrubs the gases with a solution of NaOH whereby Na and HSO3 are formed in solution. The HSO3 is then oxidized to form H and SO4 ions. The solution is then causticized with CaO to form NaOH and precipitate CaSO4. The precipitated CaSO4 and the fly ash collected in the scrubber are then separated from the NaOH solution. The solution is then diluted with make-up water to form the NaOH scrubbing solution for recycle to the scrubber.
Inventors
- 👤 Herschel Alan Klein
- 👤 Carl Richard Bozzuto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 16:44
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/501
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
149 words
A METHOD OF REMOVING SO2 FROM A FLUE GAS STREAM COMPRISING THE STEPS OF: A. CONTACTING SAID FLUE GAS WITH AS AQUEOUS SCRUBBING SOLUTION CONTAINING NAOH AND CASO4 WHEREBY A PORTION OF SAID NAOH REACTS WITH SAID SO2 TO FORM SODIUM IONS AND BISULFITE IONS, SAID NAOH BEING PRESENT IN AN AMOUNT GREATER THAN THAT REQUIRED TO REC ACT WITH SAID SO2 WHEREBY EXCESS NAOH WILL ALWAYS BE PRESENT AND WHEREIN THE PH IS MAINTAINED IN THE RANGE OF 5.0 TO 5.6; B. CONTACTING SAID AQUEOUS SCRUBBING SOLUTION FROM STEP (A) WITH OXYGEN WHEREBY SAID BISULFITE IONS ARE OXIDIZED TO FORM HYDROGEN IONS AND AND SULFATE IONS IN SOLUTION; C. CONTACTING SAID AQUEOUS SCRUBBING SOLUTION FROM STEP (B) WITH CAO WHEREBY CASO4 IS PRECIPITATED AND NAOH IS FORMED IN SOLUTION; D. SEPARATING PRECIPITATED CASO4 FROM SAID AQUEOUS SCRUBBEING SOLUTION; AND E. RECYCLING SAID AQUEOUS SCRUBBING SOLUTION TO STEP (A).
Claim 2
Independent Claim
149 words
A METHOD OF REMOVING SO2 FROM A FLUE GAS STREAM COMPRISING THE STEPS OF: A. CONTACTING SAID FLUE GAS WITH AS AQUEOUS SCRUBBING SOLUTION CONTAINING NAOH AND CASO4 WHEREBY A PORTION OF SAID NAOH REACTS WITH SAID SO2 TO FORM SODIUM IONS AND BISULFITE IONS, SAID NAOH BEING PRESENT IN AN AMOUNT GREATER THAN THAT REQUIRED TO REC ACT WITH SAID SO2 WHEREBY EXCESS NAOH WILL ALWAYS BE PRESENT AND WHEREIN THE PH IS MAINTAINED IN THE RANGE OF 5.0 TO 5.6; B. CONTACTING SAID AQUEOUS SCRUBBING SOLUTION FROM STEP (A) WITH OXYGEN WHEREBY SAID BISULFITE IONS ARE OXIDIZED TO FORM HYDROGEN IONS AND AND SULFATE IONS IN SOLUTION; C. CONTACTING SAID AQUEOUS SCRUBBING SOLUTION FROM STEP (B) WITH CAO WHEREBY CASO4 IS PRECIPITATED AND NAOH IS FORMED IN SOLUTION; D. SEPARATING PRECIPITATED CASO4 FROM SAID AQUEOUS SCRUBBEING SOLUTION; AND E. RECYCLING SAID AQUEOUS SCRUBBING SOLUTION TO STEP (A).
Claim 3
Independent Claim
147 words
A method of removing SO2 from a flue gas stream comprising the steps of: a. contacting said flue gas with an aqueous scrubbing solution containing NaOH and CaSO4 whereby a portion of said NaOH reacts with said SO2 to form sodium ions and bisulfite ions, said NaOH being present in an amount greater than that required to react with said SO2 whereby excess NaOH will always be present and wherein the pH is maintained in the range of 5.0 to 5.6; b. contacting said aqueous scrubbing solution from step (a) with oxygen whereby said bisulfite ions are oxidized to form hydrogen ions and sulfate ions in solution; c. contacting said aqueous scrubbing solution from step (b) with CaO whereby CaSO4 is precipitated and NaOH is formed in solution; d. separating precipitated CaSO4 from said aqueous scrubbing solution; and e. recycling said aqueous scrubbing solution to step (a).
Claim 4
Independent Claim
147 words
A method of removing SO2 from a flue gas stream comprising the steps of: a. contacting said flue gas with an aqueous scrubbing solution containing NaOH and CaSO4 whereby a portion of said NaOH reacts with said SO2 to form sodium ions and bisulfite ions, said NaOH being present in an amount greater than that required to react with said SO2 whereby excess NaOH will always be present and wherein the pH is maintained in the range of 5.0 to 5.6; b. contacting said aqueous scrubbing solution from step (a) with oxygen whereby said bisulfite ions are oxidized to form hydrogen ions and sulfate ions in solution; c. contacting said aqueous scrubbing solution from step (b) with CaO whereby CaSO4 is precipitated and NaOH is formed in solution; d. separating precipitated CaSO4 from said aqueous scrubbing solution; and e. recycling said aqueous scrubbing solution to step (a).
Claim 5
Dependent Claim
32 words
A method as recited in claim 1 and further including the step of adding make-up water and Na2SO4 to said aqueous scrubbing solution subsequent to step (a) and prior to step (c).
Claim 6
Dependent Claim
28 words
A method as recited in claim 1 and further including the step of washing said separated precipitated CaSO4 with water and returning said washing water to step (a).
Claim 7
Dependent Claim
23 words
A method as recited in claim 3 and further including the step of adding additional make-up water to said recycled aqueous scrubbing solution.
Claim 8
Dependent Claim
16 words
A method as recited in claim 1 wherein the pH following step (b) is about 2.0.
References Cited (Backward Citations)
US1271899A
Cited
US2161056A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-10 | 1978-09-09 | 1979-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-10 | 1982-09-09 | 1983-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-10 | 1986-09-09 | 1987-03-11 | $7700.00 | Window Closed / Lapsed |