US4246245A
Expired / Lapsed
US
⏱️ 0.0 years remaining
SO2 Removal
Assignee: Bechtel Group Inc
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Filing: 1979-01-02
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Granted: 1981-01-20
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Expires: 1999-01-02
Abstract
Abstract Improved methods are provided for the efficient and economic removal of sulfur dioxide from gases which comprise contacting the gas with neutralizing values obtained from Type S hydrated lime, i.e. calcined dolomite slaked with water under elevated temperature and pressure. The Type S hydrated dolomitic lime may be used in conjunction with a wet scrubber to provide base and neutralizing magnesium values, in a spray dryer or dry scrubber, or directly introduced into the boiler. The use of Type S hydrated dolomitic lime greatly enhances the efficiency of sulfur dioxide removal, providing for enhanced utilization of base values and more rapid rate of reaction.
Inventors
- 👤 Jack Z. Abrams
- 👤 Robert M. Sherwin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:54
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/501
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
227 words
A continuous method for reducing the sulfur dioxide content of a sulfur dioxide containing gas which comprises: contacting said sulfur dioxide containing gas in a wet scrubbing zone with recycle tank slurry having an amount of magnesium sulfite at least sufficient to neutralize said sulfur dioxide to a predetermined value to provide an exhaust gas having a substantially reduced amount of sulfur dioxide and a wet scrubbing zone effluent containing magnesium primarily as its sulfite, bisulfite and sulfate; and wherein said recycle tank slurry is substantially free of calcium containing sulfur dioxide neutralizing values to inhibit scale formation. transferring said wet scrubbing zone effluent to a recycle tank; transferring a sidestream from said recycle tank, in an amount for continuously replenishing magnesium sulfite in said wet scrubbing zone, to an oxidizer zone; oxidizing said magnesium sulfite and bisulfite to magnesium sulfate to provide an oxidizer effluent stream; transferring at least a portion of said oxidizer effluent stream to a reaction zone, where said magnesium sulfate is reacted with calcium hydroxide to provide magnesium hydroxide and insoluble calcium sulfate and make-up magnesium is added as Type S hydrated dolomitic lime to provide an alkaline effluent; transferring said alkaline effluent to said recycle tank to mix with said wet scrubbing zone effluent to provide said recycle tank slurry; and transferring said recycle tank effluent to said wet scrubbing zone.
Claim 2
Dependent Claim
227 words
A continuous method for reducing the sulfur dioxide content of a sulfur dioxide containing gas which comprises: contacting said sulfur dioxide containing gas in a wet scrubbing zone with recycle tank slurry having an amount of magnesium sulfite at least sufficient to neutralize said sulfur dioxide to a predetermined value to provide an exhaust gas having a substantially reduced amount of sulfur dioxide and a wet scrubbing zone effluent containing magnesium primarily as its sulfite, bisulfite and sulfate; and wherein said recycle tank slurry is substantially free of calcium containing sulfur dioxide neutralizing values to inhibit scale formation. transferring said wet scrubbing zone effluent to a recycle tank; transferring a sidestream from said recycle tank, in an amount for continuously replenishing magnesium sulfite in said wet scrubbing zone, to an oxidizer zone; oxidizing said magnesium sulfite and bisulfite to magnesium sulfate to provide an oxidizer effluent stream; transferring at least a portion of said oxidizer effluent stream to a reaction zone, where said magnesium sulfate is reacted with calcium hydroxide to provide magnesium hydroxide and insoluble calcium sulfate and make-up magnesium is added as Type S hydrated dolomitic lime to provide an alkaline effluent; transferring said alkaline effluent to said recycle tank to mix with said wet scrubbing zone effluent to provide said recycle tank slurry; and transferring said recycle tank effluent to said wet scrubbing zone.
Claim 3
Dependent Claim
39 words
A method according to claim 1, including transferring a sidestream from said recycle tank to a settling zone; and separating said side stream into a sludge and a supernatant liquid and returning said supernatant liquid to said recycle tank.
Claim 4
Dependent Claim
25 words
A method according to claim 2, including transferring a portion of said sludge to said reaction zone to maintain a relatively constant suspended solids level.
Claim 5
Independent Claim
43 words
A method according to any of claims 1 to 3, wherein the pH of said alkaline effluent is in the range of about 9 to 10 and the pH of said recycle tank slurry is in the range of about 6 to 7.5
Claim 6
Dependent Claim
44 words
A method according to claim 1 including transferring a substantially calcium sulfite free sidestream from said recycle tank to a settling zone; separating said sidestream into a substantially magnesium free sludge and a supernatant liquid; and returning said supernatant liquid to said recycle tank.
Claim 7
Dependent Claim
22 words
A method according to claim 1, wherein calcium present in said recycle tank slurry is present as calcium sulfate and fly ash.
Claim 8
Dependent Claim
44 words
A method according to claim 6 including transferring a substantially calcium sulfite free sidestream from said recycle tank to a settling zone; separating said sidestream into a substantially magnesium free sludge and a supernatant liquid; and returning said supernatant liquid to said recycle tank.
Claim 9
Dependent Claim
25 words
A method according to claim 1, including the step of adding make-up water from cooling tower blowdown to said recycle tank or mist eliminator washing.
Claim 10
Independent Claim
47 words
A method according to claims 1, 6, or 8 including transferring a substantially calcium sulfite free sidestream from said recycle tank to a settling zone; separating said sidestream into a substantially magnesium free sludge and a supernatant liquid; and returning said supernatant liquid to said recycle tank.
Claim 11
Dependent Claim
231 words
A continuous method for reducing the sulfur dioxide content of a sulfur dioxide containing gas which comprises: contacting said sulfur dioxide containing gas in a wet scrubbing zone with recycle tank slurry having an amount of magnesium sulfite at least sufficient to neutralize said sulfur dioxide to a predetermined value to provide an exhaust gas having a substantially reduced amount of sulfur dioxide and a wet scrubbing zone effluent containing magnesium primarily as its sulfite, bisulfite, and sulfate; and wherein said recyle tank slurry is substantially free of calcium containing sulfur dioxide neutralizing values to inhibit scale formation; transferring said wet scrubbing zone effluent to a recycle tank; transferring a sidestream from said recycle tank in an amount for continuously replenishing magnesium sulfite in said wet scrubbing zone, to an oxidizer zone; oxidizing said magnesium sulfite and bisulfite to magnesium sulfate to provide an oxidizer effluent stream; transferring at least a portion of said oxidizer effluent stream to a reaction zone, where said magnesium sulfate is reacted with calcium hydroxide to provide magnesium hydroxide and make-up magnesium is added, in an amount sufficient to maintain the desired magnesium concentration in said recycle tank, to provide an alkaline effluent; transferring said alkaline effluent to said recycle tank to mix with said wet scrubbing zone effluent to provide said recycle tank slurry; and transferring said recycle tank effluent to said wet scrubbing zone.
Claim 12
Dependent Claim
231 words
A continuous method for reducing the sulfur dioxide content of a sulfur dioxide containing gas which comprises: contacting said sulfur dioxide containing gas in a wet scrubbing zone with recycle tank slurry having an amount of magnesium sulfite at least sufficient to neutralize said sulfur dioxide to a predetermined value to provide an exhaust gas having a substantially reduced amount of sulfur dioxide and a wet scrubbing zone effluent containing magnesium primarily as its sulfite, bisulfite, and sulfate; and wherein said recyle tank slurry is substantially free of calcium containing sulfur dioxide neutralizing values to inhibit scale formation; transferring said wet scrubbing zone effluent to a recycle tank; transferring a sidestream from said recycle tank in an amount for continuously replenishing magnesium sulfite in said wet scrubbing zone, to an oxidizer zone; oxidizing said magnesium sulfite and bisulfite to magnesium sulfate to provide an oxidizer effluent stream; transferring at least a portion of said oxidizer effluent stream to a reaction zone, where said magnesium sulfate is reacted with calcium hydroxide to provide magnesium hydroxide and make-up magnesium is added, in an amount sufficient to maintain the desired magnesium concentration in said recycle tank, to provide an alkaline effluent; transferring said alkaline effluent to said recycle tank to mix with said wet scrubbing zone effluent to provide said recycle tank slurry; and transferring said recycle tank effluent to said wet scrubbing zone.
Claim 13
Dependent Claim
38 words
A method according to claim 10, including transferring a sidestream from said recycle tank to a settling zone; and separating said sidestream into a sludge and a supernatant liquid and returning said supernatant liquid to said recycle tank.
Claim 14
Independent Claim
43 words
A method according to any of claims 10 and 11, wherein the pH of said alkaline effluent is in the range of about 9 to 10 and the pH of said recycle tank slurry is in the range of about 6 to 7.5.
Claim 15
Dependent Claim
17 words
A method according to claim 11, wherein said sludge is substantially magnesium free and calcium sulfite free.
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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) | 1984-01-20 | 1984-07-21 | 1985-01-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-20 | 1988-07-21 | 1989-01-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-20 | 1992-07-21 | 1993-01-20 | $7700.00 | Window Closed / Lapsed |