US3938206A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for continuous displacement washing of liquid-containing pulp materials
Assignee: Individual
•
Filing: 1974-01-08
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Granted: 1976-02-17
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Expires: 1994-01-08
Abstract
Abstract Liquid-containing pulp material, especially sulphate pulp containing black liquor, is deposited as a mat on a moving filter and subjected to displacement washing with a liquid such as clean water supplied to one side of the pulp mat and displacing the black liquor, which emerges in substantially undiluted form from the opposite side of the mat. The filter is a screen moving over a supporting floor, said floor and screen together forming a "resistance floor" providing a substantial flow resistance to the liquid. A layer of displacement or washing liquid (e.g., water) is maintained over the pulp mat covering the surface thereof. This layer may have a depth or height of e.g. 10 to 100 cm, thus protecting the surface of the mat against the effect of supply means for displacement liquid and providing a pressure on the upper side of the pulp mat assisting in overcoming the flow resistance of the pulp and the floor.
Inventors
- 👤 Per Stranger-Johannessen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 10:03
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/02; D21C9/06
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
150 words
A method for the continuous washing of liquid-containing pulp material with a displacement liquid, comprising traversing a filter along a predetermined path, supporting said filter throughout a substantial portion of said path upon a support floor, continuously depositing a mat of liquid-containing pulp material upon said filter for movement therewith, separately supplying displacement liquid to the upper surface of said mat of pulp material and maintaining a predetermined head of said displacement liquid thereon, said head of displacement liquid being sufficient to overcome the resistance to the flow of liquids through said mat offered by the average flow resistance of the mat and the additional resistance to flow offered by a resistance floor which includes at least one of said filter and support floor, whereby the liquids in said pulp material are continuously displaced by said displacement liquid, and recovering the displaced pulp liquids substantially undiluted by said displacement liquid.
Claim 2
Independent Claim
150 words
A method for the continuous washing of liquid-containing pulp material with a displacement liquid, comprising traversing a filter along a predetermined path, supporting said filter throughout a substantial portion of said path upon a support floor, continuously depositing a mat of liquid-containing pulp material upon said filter for movement therewith, separately supplying displacement liquid to the upper surface of said mat of pulp material and maintaining a predetermined head of said displacement liquid thereon, said head of displacement liquid being sufficient to overcome the resistance to the flow of liquids through said mat offered by the average flow resistance of the mat and the additional resistance to flow offered by a resistance floor which includes at least one of said filter and support floor, whereby the liquids in said pulp material are continuously displaced by said displacement liquid, and recovering the displaced pulp liquids substantially undiluted by said displacement liquid.
Claim 3
Dependent Claim
59 words
A method according to claim 1, wherein said pulp material is fed to an inlet chamber positioned upstream of said filter and is accumulated therein to such level that the hydrostatic pressure at the level of the upper surface of said mat is substantially equal to the hydrostatic pressure of the displacement liquid at said surface of the mat.
Claim 4
Dependent Claim
56 words
A method according to claim 1, wherein said resistance floor is said support floor, said support floor being liquid-permeable, said displaced pulp liquids being urged through said resistance floor for recovery at a plurality of locations therealong, regulating the rate of advance of said filter to recover displaced pulp liquids from said locations at predetermined concentrations.
Claim 5
Dependent Claim
23 words
A method according to claim 3, wherein the liquids recovered from selected ones of said locations are recycled for use as displacement liquids.
Claim 6
Dependent Claim
59 words
A method according to claim 4, wherein said pulp material is fed to an inlet chamber positioned upstream of said filter and is accumulated therein to such level that the hydrostatic pressure at the level of the upper surface of said mat is substantially equal to the hydrostatic pressure of the displacement liquid at said surface of the mat.
Claim 7
Dependent Claim
59 words
A method according to claim 3, wherein said pulp material is fed to an inlet chamber positioned upstream of said filter and is accumulated therein to such level that the hydrostatic pressure at the level of the upper surface of said mat is substantially equal to the hydrostatic pressure of the displacement liquid at said surface of the mat.
Claim 8
Dependent Claim
22 words
A method according to claim 1, wherein said mat of liquid-containing pulp material is deposited upon a screen filter for movement thereupon.
Claim 9
Dependent Claim
17 words
A method according to claim 1, wherein said liquid-containing pulp material comprises sulphate pulp containing black liquor.
References Cited (Backward Citations)
US3454970A
Cited
US3832283A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-02-16 | 1979-08-18 | 1980-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-02-16 | 1983-08-18 | 1984-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-02-16 | 1987-08-18 | 1988-02-17 | $7700.00 | Window Closed / Lapsed |