Patent US3788469A successfully refreshed from Google Patents.
US3788469A
Expired / Lapsed
US
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Process for removing ash from precipitators
Assignee: New England Power Co
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Filing: 1972-07-13
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Granted: 1974-01-29
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Expires: 1992-07-13
Abstract
Abstract A process for removing fuel ash from precipitator bottoms circulates water through the bottoms to carry off the ash, then passes the water at least in part through a hydrocyclone separation stage to produce a major overflow fraction of reduced solids content and a minor overflow fraction of increased solids content, and recirculates the water withdrawn from the bottoms less the underflow fraction back through the bottoms at a rate to maintain the solids concentration less than that at which substantial settling out of solids will occur. Preferably, the recirculation is continuous, and the underflow from said hydrocyclone separation stage is subjected to secondary stage hydrocyclone separation from which the underflow may be subjected to tertiary stage solids separation, the overflow from one or both further separation stages being recirculated.
Inventors
- 👤 E Hirsch
- 👤 G Nelson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 10:36
CPC Classifications
B; B01; B01D; B01D21/00; B01D21/26; B01D21/267; B01D21/24; B01D21/2488; B01D21/30; B01D21/34; B01D47/00; B01D47/02; B01D47/021
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
21 words
A process according to claim 1 wherein said withdrawal and recirculation steps are continuous and at the same volumetric flow rate.
Claim 2
Dependent Claim
25 words
A process according to claim 1 wherein said withdrawal and recirculation steps are applied successively and in multiple to different precipitator bottoms of said system.
Claim 3
Dependent Claim
23 words
A process according to claim 1 wherein about 30 to 70 percent of said withdrawn ash-containing water is subjected to said centrifugal separation.
Claim 4
Dependent Claim
24 words
A process according to claim 2 wherein said ash from said system is collected in a continuously flowing Stream of said water exposed thereto.
Claim 5
Dependent Claim
29 words
A process according to claim 1 wherein said minor underflow fraction is of the order of 5 percent or less of the feed to said primary hydrocyclone separator stage.
Claim 6
Dependent Claim
57 words
A process according to claim 1 which includes the further steps of: subjecting said minor underflow fraction to centrifugal separation in a secondary hydrocyclone separator stage to provide a major overflow fraction of reduced solids content and a minor underflow fraction of increased solids content; and recirculating said major overflow fraction of said secondary hydrocyclone separator stage.
Claim 7
Dependent Claim
33 words
A process according to claim 7 wherein said minor underflow fraction of said secondary hydrocyclone stage is of the order of 2 to 10 percent of the feed to said last named stage.
Claim 8
Dependent Claim
27 words
A process according to claim 7 wherein said minor underflow fraction of said secondary hydrocyclone stage is less than about 0.5 percent of said recirculated withdrawn water.
Claim 9
Dependent Claim
49 words
A process according to claim 7 which includes the further step of subjecting said minor underflow fraction of said secondary hydrocyclone separation stage to a tertiary stage solids separation treatment to provide a major overflow fraction of reduced solids content and a minor underflow fraction of increased solids content.
Claim 10
Dependent Claim
18 words
A process according to claim 10 wherein said major overflow fraction of said tertiary stage treatment is recirculated.
Claim 11
Dependent Claim
13 words
A process according to claim 10 wherein said tertiary stage treatment is centrifuging.
Claim 12
Dependent Claim
13 words
A process according to claim 10 wherein said tertiary stage treatment is filtering.
Claim 13
Dependent Claim
27 words
A process according to claim 1 which includes the further step of segregating a part of said withdrawn recirculated water for treatment for recovery of solids therefrom.
Claim 14
Dependent Claim
19 words
A process according to claim 1 which includes the further step of adding chemical to said withdrawn recirculated water.
Claim 15
Dependent Claim
27 words
A process according to claim 2 wherein said volumetric flow rate is at least 1,000 gallons per hour per pound of ash discharged from said precipitator system.
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) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |