US3717700A
Expired / Lapsed
US
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Process and apparatus for burning sulfur-containing fuels
Assignee: United States Department of the Interior
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Filing: 1970-08-25
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Granted: 1973-02-20
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Expires: 1990-08-25
Abstract
Abstract Sulfur-containing fuels such as coal are burned in a two-zone system. Circulating sulfur acceptor material absorbs sulfur in the first zone and releases it in the second zone thus concentrating most of the sulfur oxides in a small fraction of the flue gas.
Inventors
- 👤 E Robison
- 👤 S Ehrlich
- 👤 J Bishop
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:19
CPC Classifications
F; F23; F23C; F23C10/00; F23C10/005; C; C01; C01B; C01B17/00; C01B17/48; C01B17/50; C01B17/60
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
222 words
A process for burning sulfur containing fuels which comprises: providing a first and a second combustion zone, the second zone comprising a fluidized bed of particulate material having heat exchange means disposed therein; burning a sulfur-containing fuel in the first zone in association with a solid, particulate, alkaline earth oxide sulfur accepting material; maintaining temperatures within the first zone at a level above about 1400* F whereat sulfur compounds produced in the combustion process react with the sulfur accepting material to form a sulfated alkaline earth oxide; removing from the first zone at least a portion of the sulfated alkaline earth oxide and introducing it into the fluidized bed of the second zone; burning fuel within the fluidized bed of the second zone in association with the introduced sulfated alkaline earth oxide; maintaining the second combustion zone at a higher temperature than that at which sulfur is accepted by the alkaline earth oxide in the first zone, said higher temperature being in the range of 1700* to 2100* F; supplying oxygen to the second combustion zone in amounts sufficient to maintain the concentration of unreacted oxygen in the flue gas issuing from that zone above about 0.5 percent, and removing from the first zone a flue gas depleted in sulfur and removing from the second zone a flue gas enriched in sulfur.
Claim 2
Dependent Claim
222 words
A process for burning sulfur containing fuels which comprises: providing a first and a second combustion zone, the second zone comprising a fluidized bed of particulate material having heat exchange means disposed therein; burning a sulfur-containing fuel in the first zone in association with a solid, particulate, alkaline earth oxide sulfur accepting material; maintaining temperatures within the first zone at a level above about 1400* F whereat sulfur compounds produced in the combustion process react with the sulfur accepting material to form a sulfated alkaline earth oxide; removing from the first zone at least a portion of the sulfated alkaline earth oxide and introducing it into the fluidized bed of the second zone; burning fuel within the fluidized bed of the second zone in association with the introduced sulfated alkaline earth oxide; maintaining the second combustion zone at a higher temperature than that at which sulfur is accepted by the alkaline earth oxide in the first zone, said higher temperature being in the range of 1700* to 2100* F; supplying oxygen to the second combustion zone in amounts sufficient to maintain the concentration of unreacted oxygen in the flue gas issuing from that zone above about 0.5 percent, and removing from the first zone a flue gas depleted in sulfur and removing from the second zone a flue gas enriched in sulfur.
Claim 3
Dependent Claim
37 words
The process of claim 1 wherein the first combustion zone comprises a pulverized coal boiler and wherein the alkaline earth oxide sulfur accepting material is introduced in finely divided form at a point removed from the flame.
Claim 4
Dependent Claim
41 words
The process of claim 2 wherein sulfated alkaline earth oxide particles entrained in flue gases issuing from the first zone are removed from the flue gas by mechanical meanS and are pneumatically injected into the fluidized bed of the second zone.
Claim 5
Dependent Claim
29 words
The process of claim 1 wherein the first combustion zone comprises a fluidized bed boiler operated at a temperature within the range of about 1500* to about 1700* F.
Claim 6
Dependent Claim
30 words
The process of claim 4 wherein the unreacted oxygen content of the combustion gases produced in the first combustion zone is within the range of about 0.5 to 5 percent.
Claim 7
Dependent Claim
28 words
The process of claim 5 wherein the unreacted oxygen content of the gases issuing from the second zone is within the range of about 0.5 to 2.5 percent.
Claim 8
Dependent Claim
18 words
The process of claim 6 wherein the fuel burned in the first combustion zone comprises particulate, sulfur-containing coal.
Claim 9
Dependent Claim
54 words
The process of claim 7 wherein solids entrained in flue gases issuing from the first combustion zone and comprising a mixture of sulfated alkaline earth oxide, fly ash particles and unburned carbonaceous material, are removed from the flue gas by mechanical means and are pneumatically injected into the fluidized bed of the second zone.
Claim 10
Dependent Claim
28 words
The process of claim 8 wherein the particulate material making up the fluidized beds of the first and second combustion zones comprises an alkaline earth oxide sulfur acceptor.
Claim 11
Dependent Claim
13 words
The process of claim 9 wherein the alkaline earth oxide comprises calcium oxide.
Claim 12
Dependent Claim
21 words
The process of claim 10 wherein the calcium oxide is formed within the combustion zones by calcination of calcium carbonate-containing materials.
Claim 13
Dependent Claim
37 words
The process of claim 11 wherein sulfated calcium oxide fluidized bed material is circulated from the first to the second combustion zones and wherein regenerated calcium oxide is returned from the second zone to the first zone.
Claim 14
Dependent Claim
18 words
The process of claim 12 wherein the first combustion zone is substantially larger than the second combustion zone.
Claim 15
Dependent Claim
31 words
The process of claim 13 wherein the quantity of flue gas produced by the second combustion zone is less than 1/4 of the total flue gas produced by the two zones.
Claim 16
Dependent Claim
33 words
The process of claim 14 wherein sulfur oxides produced by decomposition of sulfated calcium oxide and contained in the flue gas issuing from the second zone are removed from the flue gas stream.
Claim 17
Dependent Claim
23 words
The process of claim 15 wherein said sulfur removal comprises reaction of the sulfur oxides by the contact process to form sulfuric acid.
Claim 18
Dependent Claim
29 words
The process of claim 16 wherein the fuel burned in the second combustion zone has a higher sulfur content than does the fuel burned in the first combustion zone.
Claim 19
Dependent Claim
55 words
The process of claim 31 wherein the flue gas from the second combustion zone is cooled prior to said liquid scrubbing and wherein said flue gas, after being depleted of sulfur oxides, is merged with the flue gas of the first combustion zone and wherein the combined flue gas streams are passed to a stack.
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) | 1976-02-20 | 1976-08-21 | 1977-02-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-20 | 1980-08-21 | 1981-02-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-20 | 1984-08-21 | 1985-02-20 | $7700.00 | Window Closed / Lapsed |