Patent JPS50108653A successfully refreshed from Google Patents.
US3878698A
Expired / Lapsed
US
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Apparatus for forming and washing a fibrous web
Assignee: Metso Fiber Karlstad AB
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Filing: 1974-01-21
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Granted: 1975-04-22
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Expires: 1994-01-21
Abstract
Abstract A layer of fibrous material is formed from a suspension of the fibrous material in a suspension liquid by introducing the suspension into a web-forming space defined between a member impermeable to the suspension liquid and a member that is permeable to the suspension liquid but substantially impermeable to the fibrous material and that is moved along an endless path. The thickness of the web-forming space diminishes from the upstream end to the downstream end thereof, relative to the direction of movement of the permeable member. As the suspension moves through the web-forming space, liquid drains through the liquid permeable member under the influence of pressure developed by the delivery pressure, coupled with the convergence of the space, thereby producing a fibrous layer in the web-forming space. The fibrous layer is washed by supplying liquid under pressure through a permeable element positioned opposite the permeable member downstream from the web-forming space. The volumetric flow rate of liquid is controlled so that the wash liquid displaces the suspension liquid in the web to a depth that is less than the thickness of the layer. The remaining suspension liquid and a small amount of wash liquid are ultimately displaced from the web in a press nip.
Inventors
- 👤 Erik Sture Friksson
- 👤 Gosta Ingemar Ingemarsson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 16:08
CPC Classifications
D; D21; D21G; D21G9/00; D21G9/0009; D21C; D21C9/00; D21C9/02; D21C9/06; D21C9/18; D21F; D21F9/00; D21F9/04
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
250 words
In apparatus for forming a layer of fibrous material from a suspension of the fibrous material in a suspension liquid and for washing the layer with a wash liquid, the apparatus including a member permeable to the liquids and substantially impermeable to the fibrous material, means for moving the permeable member along an endless path, a member positioned opposite the permeable member and defining with the permeable member a layer-forming space the thickness of which diminishes from the upstream end of such space to the downstream end, relative to the direction of movement of the permeable member, means for supplying the suspension of fibrous material to the upstream end of the forming space, a liquid permeable element positioned opposite a portion of the permeable member immediately downstream from the downstream end of the layer-forming space and defining with the permeable member a washing zone, means for supplying washing liquid under pressure through the permeable element to the washing zone, and a press roll positioned opposite the permeable member and defining therewith a press nip adjacent the downstream end of the washing zone, the improvement comprising means for monitoring the pressure in the layer of fibrous material at the press nip and producing a nip-pressure signal indicative thereof, means for varying the volumetric rate of flow of fibrous material through the nip and for producing a rate signal indicative thereof, and means for controlling the volumetric flow rate of washing liquid to the washing zone in response to said rate signal.
Claim 2
Dependent Claim
250 words
In apparatus for forming a layer of fibrous material from a suspension of the fibrous material in a suspension liquid and for washing the layer with a wash liquid, the apparatus including a member permeable to the liquids and substantially impermeable to the fibrous material, means for moving the permeable member along an endless path, a member positioned opposite the permeable member and defining with the permeable member a layer-forming space the thickness of which diminishes from the upstream end of such space to the downstream end, relative to the direction of movement of the permeable member, means for supplying the suspension of fibrous material to the upstream end of the forming space, a liquid permeable element positioned opposite a portion of the permeable member immediately downstream from the downstream end of the layer-forming space and defining with the permeable member a washing zone, means for supplying washing liquid under pressure through the permeable element to the washing zone, and a press roll positioned opposite the permeable member and defining therewith a press nip adjacent the downstream end of the washing zone, the improvement comprising means for monitoring the pressure in the layer of fibrous material at the press nip and producing a nip-pressure signal indicative thereof, means for varying the volumetric rate of flow of fibrous material through the nip and for producing a rate signal indicative thereof, and means for controlling the volumetric flow rate of washing liquid to the washing zone in response to said rate signal.
Claim 3
Dependent Claim
250 words
In apparatus for forming a layer of fibrous material from a suspension of the fibrous material in a suspension liquid and for washing the layer with a wash liquid, the apparatus including a member permeable to the liquids and substantially impermeable to the fibrous material, means for moving the permeable member along an endless path, a member positioned opposite the permeable member and defining with the permeable member a layer-forming space the thickness of which diminishes from the upstream end of such space to the downstream end, relative to the direction of movement of the permeable member, means for supplying the suspension of fibrous material to the upstream end of the forming space, a liquid permeable element positioned opposite a portion of the permeable member immediately downstream from the downstream end of the layer-forming space and defining with the permeable member a washing zone, means for supplying washing liquid under pressure through the permeable element to the washing zone, and a press roll positioned opposite the permeable member and defining therewith a press nip adjacent the downstream end of the washing zone, the improvement comprising means for monitoring the pressure in the layer of fibrous material at the press nip and producing a nip-pressure signal indicative thereof, means for varying the volumetric rate of flow of fibrous material through the nip and for producing a rate signal indicative thereof, and means for controlling the volumetric flow rate of washing liquid to the washing zone in response to said rate signal.
Claim 4
Dependent Claim
250 words
In apparatus for forming a layer of fibrous material from a suspension of the fibrous material in a suspension liquid and for washing the layer with a wash liquid, the apparatus including a member permeable to the liquids and substantially impermeable to the fibrous material, means for moving the permeable member along an endless path, a member positioned opposite the permeable member and defining with the permeable member a layer-forming space the thickness of which diminishes from the upstream end of such space to the downstream end, relative to the direction of movement of the permeable member, means for supplying the suspension of fibrous material to the upstream end of the forming space, a liquid permeable element positioned opposite a portion of the permeable member immediately downstream from the downstream end of the layer-forming space and defining with the permeable member a washing zone, means for supplying washing liquid under pressure through the permeable element to the washing zone, and a press roll positioned opposite the permeable member and defining therewith a press nip adjacent the downstream end of the washing zone, the improvement comprising means for monitoring the pressure in the layer of fibrous material at the press nip and producing a nip-pressure signal indicative thereof, means for varying the volumetric rate of flow of fibrous material through the nip and for producing a rate signal indicative thereof, and means for controlling the volumetric flow rate of washing liquid to the washing zone in response to said rate signal.
Claim 5
Dependent Claim
85 words
The improvement according to claim 1 wherein the means for controlling the supply of wash liquid is responsive to said rate signal to supply wash liquid at a volumetric flow rate such that the wash liquid displaces suspension liquid from the fibrous layer to a depth A adjaCent the downstream end of the washing zone less than the total thickness of the layer adjacent the downstream end of the washing zone, and wherein the thickness B of the nip is less than said depth A.
Claim 6
Dependent Claim
52 words
The improvement according to claim 1 wherein the means for varying the volumetric flow rate of fibrous material through the nip includes means for varying the speed of movement of the permeable member, and wherein the means for supplying the suspension of fibrous material supplies the suspension at a substantially constant rate.
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) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |