US4623523A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for reduction of SO2 emission for fossil fired boiler
Assignee: Bechtel Group Inc
•
Filing: 1985-03-18
•
Granted: 1986-11-18
•
Expires: 2005-03-18
Abstract
Abstract Apparatus and method for the efficient and economic removal of sulfur dioxide from gases, in which the gas is contacted with neutralizing values obtained from presure hydrated lime or pressure hydrated dolomitic lime, i.e. calcined limestone or dolomite and slaked with water under elevated temperature and pressure. The pressure hydrated lime or dolomitic lime may be used in conjunction with a wet scrubber, in a spray dryer or dry scrubber, or directly introduced into the gas passages of a boiler, upstream or downstream of the air preheater, or in the boiler output ducting or the inlet of an electrostatic precipitator. The use of pressure hydrated lime or pressure hydrated dolomitic lime greatly enhances the efficiency of sulfur dioxide removal, thereby providing for enhanced use of base values and a more rapid rate of reaction. The confined zone dispersion scheme permits a partial SO 2 removal (10%-50%) without a scrubber, only by atomizing a slurry of pressure hydrated lime or pressure hydrated dolomitic lime into the flue gas duct of the boiler.
Inventors
- 👤 Jack Z. Abrams
- 👤 Robert M. Sherwin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 14:53
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
124 words
A method for removing sulfur dioxide from a sulfur dioxide-containing flue gas comprising: injecting small particles of an aqueous dispersion of material selected from the group consisting of pressure hydrated lime and pressure hydrated dolomitic lime into a confined zone within a flue gas stream flowing in a duct in an amount sufficiently large to reduce the sulfur dioxide content of said flue gas to a level equivalent to between 10% and 90% of the original sulfur dioxide content but sufficiently small so that the aqueous dispersion is completely dried within within the confined zone, in a stoichiometric ratio to said sulfur dioxide of not larger than 1.5, wherein said confined zone is spaced-apart from the inside walls of the duct and completely dry.
Claim 2
Independent Claim
124 words
A method for removing sulfur dioxide from a sulfur dioxide-containing flue gas comprising: injecting small particles of an aqueous dispersion of material selected from the group consisting of pressure hydrated lime and pressure hydrated dolomitic lime into a confined zone within a flue gas stream flowing in a duct in an amount sufficiently large to reduce the sulfur dioxide content of said flue gas to a level equivalent to between 10% and 90% of the original sulfur dioxide content but sufficiently small so that the aqueous dispersion is completely dried within within the confined zone, in a stoichiometric ratio to said sulfur dioxide of not larger than 1.5, wherein said confined zone is spaced-apart from the inside walls of the duct and completely dry.
Claim 3
Dependent Claim
25 words
A method as set forth in claim 1, wherein said gas is contacted with the material dispersion in the boiler outlet ducting of a boiler.
Claim 4
Dependent Claim
24 words
A method as set forth in claim 1, wherein said gas is contacted with the material dispersion in the inlet of an electrostatic precipitator.
Claim 5
Dependent Claim
27 words
A method as set forth in claim 1, wherein said confined zone is defined by a surrounding slip zone of the flue gas in the flue duct.
Claim 6
Dependent Claim
20 words
A method as set forth in claim 1, wherein the aqueous dispersion has at least about five weight percent solids.
Claim 7
Dependent Claim
18 words
A method as set forth in claim 1, wherein said aqueous dispersion is atomized with a rotary atomizer.
Claim 8
Dependent Claim
19 words
A method as set forth in claim 1, wherein the aqueous dispersion is atomized with a piezo-electric driven nozzle.
Claim 9
Dependent Claim
22 words
A method as set forth in claim 1, wherein the aqueous dispersion is atomized in successive places in the flue gas stream.
Claim 10
Dependent Claim
18 words
A method as set forth in claim 1, wherein the aqueous dispersion is atomized with a pressurized gas.
Claim 11
Dependent Claim
14 words
A method as set forth in claim 9, wherein said gas is compressed air.
Claim 12
Independent Claim
74 words
A method for removing sulfur dioxide from a sulfur dioxide-containing flue gas stream flowing within a duct, said method comprising axially spraying an aqueous slurry of a sulfur-dioxide scavenger selected from the group consisting of pressure hydrated lime and pressure hydrated dolomitic lime near the center of the duct so that absorption occurs and the aqueous slurry is completely dried within a confined dispersion zone spaced apart from the inside walls of the duct.
Claim 13
Independent Claim
74 words
A method for removing sulfur dioxide from a sulfur dioxide-containing flue gas stream flowing within a duct, said method comprising axially spraying an aqueous slurry of a sulfur-dioxide scavenger selected from the group consisting of pressure hydrated lime and pressure hydrated dolomitic lime near the center of the duct so that absorption occurs and the aqueous slurry is completely dried within a confined dispersion zone spaced apart from the inside walls of the duct.
Claim 14
Dependent Claim
23 words
A method as in claim 11, wherein the stoichiometric ratio of scavenger to sulfur dioxide is in the range from 1.0 to 1.5.
Claim 15
Dependent Claim
16 words
A method as in claim 11, wherein the duct is an inlet to an electrostatic precipitator.
References Cited (Backward Citations)
US2718453A
Cited
US3932587A
Cited
US3904742A
Cited
US4046856A
Cited
JPS5581722A
Cited
US4246245A
Cited
US4388283A
Cited
US4452765A
Cited
US4555996A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-11-17 | 1990-05-19 | 1990-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-11-17 | 1994-05-19 | 1994-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-11-17 | 1998-05-19 | 1998-11-18 | $7700.00 | Window Closed / Lapsed |