US5219472A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of treating a fiber suspension
Assignee: Ahlstrom Corp
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Filing: 1991-07-29
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Granted: 1993-06-15
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Expires: 2011-07-29
Abstract
Abstract A method and apparatus for improving the treatment of a gas containing fiber suspension in the pulp and paper industry, especially for increasing the capacity of a screening department, a washing department, a thickening department, a press, a curved screen, or the like, includes the simultaneous separation and removal of the gases prior to the respective treatment stage.
Inventors
- 👤 Jorma Elonen
- 👤 Kaj Henricson
- 👤 Olavi Pikka
- 👤 Raimo Pitkanen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 09:55
CPC Classifications
B; B01; B01D; B01D19/00; B01D19/0042; B01D19/0052; D; D21; D21D; D21D5/00; D21D5/26
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
98 words
A method of treating a gas containing fiber suspension in one of a washing, screening and thickening stage, comprising: simultaneously pumping and degassing said fiber suspension by the rotating action of the impeller of a centrifugal pump including impeller back vanes thereby generating a foam and gas flow; subjecting said foam and gas flow to the rotating action of the pump impeller back vanes for separating said foam from said gas flow; exhausting said gas flow from said pump; and contacting said degassed fiber suspension with a perforated member in one of the washing, screening and thickening stage.
Claim 2
Independent Claim
98 words
A method of treating a gas containing fiber suspension in one of a washing, screening and thickening stage, comprising: simultaneously pumping and degassing said fiber suspension by the rotating action of the impeller of a centrifugal pump including impeller back vanes thereby generating a foam and gas flow; subjecting said foam and gas flow to the rotating action of the pump impeller back vanes for separating said foam from said gas flow; exhausting said gas flow from said pump; and contacting said degassed fiber suspension with a perforated member in one of the washing, screening and thickening stage.
Claim 3
Dependent Claim
59 words
The method according to claim 1, wherein said pumping and degassing step is performed with a degassing pump having impeller back vanes and further comprising the step of separating said fiber suspension into a substantially gas-free flow and a gas containing flow; and subjecting said gas containing flow to the rotating action of impeller back vanes of said pump.
Claim 4
Dependent Claim
38 words
The method according to claim 1, comprising the additional step of bleaching said fiber suspension with oxygen prior to said degassing step; and wherein said degassed fiber suspension is contacted with said perforated member in a screening stage.
Claim 5
Dependent Claim
16 words
The method of claim 1, comprising the additional step of exhausting said foam from said pump.
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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) | 1996-06-14 | 1996-12-14 | 1997-06-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-06-14 | 2000-12-14 | 2001-06-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-06-14 | 2004-12-14 | 2005-06-15 | $7700.00 | Window Closed / Lapsed |