US3607045A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for high temperature gaseous reduction of calcium sulfate
Assignee: Iowa State University Research Foundation Inc
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Filing: 1969-10-29
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Granted: 1971-09-21
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Expires: 1989-10-29
Abstract
Abstract Calcium sulfate is subjected to gaseous reduction at a high temperature to obtain an SO2 containing gas product and a CaO solid product. The reduction is carried out in a fluidized reaction bed by flowing proportioned air and natural gas into and through the bed to fluidize the finely divided calcium sulfate and to heat to reaction temperatures. The natural gas is only partially burned within the bed, thereby also producing reducing quantities of CO and H2. In a preferred embodiment, the calcium sulfate feed is preheated by direct contact with the gas product to recover part of the heat therefrom, and the gas product of reduced heat content is then subjected to indirect countercurrent heat exchange with the air being supplied to the reaction bed.
Inventors
- 👤 Thomas D Wheelock
- 👤 David R Boyland
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 13:38
CPC Classifications
C; C01; C01F; C01F11/00; C01F11/02; C01F11/08; C01B; C01B17/00; C01B17/48; C01B17/50; C01B17/501; C01B17/506; Y; Y02; Y02P; Y02P20/00; Y02P20/10; Y02P20/129
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
40 words
The process of claim 1 in which all of the burning of said natural gas occurs within said bed and the said calcium sulfate in said bed is subjected only to the reducing action of the resulting CO and H2.
Claim 2
Dependent Claim
38 words
The process of claim 1 in which said gas product from said bed is directly contacted with a calcium sulfate feed to said bed to preheat said feed and remove part of the heat from said gas product.
Claim 3
Dependent Claim
50 words
The process of claim 1 in which said gas product from said bed is subjected to indirect countercurrent heat exchange contact with air supplied to said bed before said air is mixed with said natural gas, thereby preheating said air and removing part of the heat from said gas product.
Claim 4
Dependent Claim
32 words
The process of claim 4 in which said preheated air is mixed with said natural gas without igniting said natural gas before the said natural gas and air are introduced into bed.
Claim 5
Dependent Claim
82 words
The process of claim 1 in which said gas product from said bed is directly contacted with a calcium sulfate feed to said bed to preheat said feed and remove part of the sensible heat from said gas product, and in combination therewith the said gas product after said partial heat removal is subjected to indirect countercurrent heat exchange contact with the air supplied to said bed, thereby preheating said air and removing more of the sensible heat from said gas product.
Claim 6
Dependent Claim
32 words
The process of claim 6 in which said preheated air is mixed with said natural gas without igniting said natural gas before its admixture with said air is introduced into said bed.
Claim 7
Dependent Claim
128 words
In a process of high temperature gaseous reduction of calcium sulfate in a fluIdized bed reactor to obtain a product gas containing recoverable SO2 and a CaO product, the steps of feeding preheated finely divided calcium sulfate to the fluidized bed of said reactor, said calcium sulfate feed being preheated by directly contacting it with said hot product gas, thereby recovering part of the sensible heat from said product gas, thereafter indirectly contacting said product gas with a stream of air to recover more of the sensible heat from said product gas, passing the resulting heated air and a supply of natural gas to said fluidized bed reactor, and partially burning said natural gas with said heated air to provide heat and reducing gas for said gaseous reduction.
Claim 8
Dependent Claim
39 words
The process of claim 8 wherein said calcium sulfate feed is preheated in a fluidized bed by passing said product gas therethrough, and the preheated feed is transferred to the fluidized bed of said reactor for said gaseous reduction.
Claim 9
Dependent Claim
27 words
The process of claim 8 in which said calcium sulfate feed is caused to flow along a tortuous path in direct countercurrent contact with said gas product.
Claim 10
Dependent Claim
69 words
The process of claim 8 in which said fluidized bed is maintained at a temperature of substantially 2,150* to 2,250* F., said calcium sulfate feed is preheated to a temperature of at least 1,500* F., said air is heated to a temperature of at least 1,400* F., and said product gas as a result of both said heat recovery steps has its temperature reduced to at least 900* F.
References Cited (Backward Citations)
US1845744A
Cited
US2232099A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |