US3821073A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multi-layer paper formation wherein outer layers are substantially free of bod substances
Assignee: KARLSTAD MEKANISKA AB
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Filing: 1972-10-02
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Granted: 1974-06-28
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Expires: 1992-10-02
Abstract
Abstract In a process for the manufacture of paper or a similar fibre sheet product the initial fibre-stock suspension, which contains BOD substances, is divided into two fibre suspension flows. One of these fibre suspension flows is conveyed to a first sheet forming stage wherein a first fibre layer is formed and dewatered. The second fibre suspension flow is first subjected to a washing process in which the original suspension water containing BOD substances is exchanged for new suspension water which is substantially free from BOD substances, and is after this washing process conveyed to one or more additional sheet forming stages wherein one or more additional fibre layers are formed and dewatered. These additional fibre layers are joined with the first fibre layer from the first sheet forming stage into a multi-layer fibre web, which is passed through a press section for further dewatering. The backwater from the first sheet forming stage and the exchanged suspension water containing BOD containing substances from the washing process is recirculated to the initial fibre-stock suspension. The backwater from the additional sheet forming stages and from the press section is preferably recirculated to the washing process and used therein for the substitution of the original suspension water containing BOD containing substances in the second fibre suspension flow.
Inventors
- 👤 E Eriksson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:13
CPC Classifications
D; D21; D21F; D21F11/00; D21F11/02; D21F11/04
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
52 words
A process as claimed in claim 1, comprising the additional step of recirculating the water being removed from said second fibre suspension flow in said additional sheet forming stage to said washing process and therein using it for substituting the original, BOD substances containing, suspension water in said second fibre suspension flow.
Claim 2
Dependent Claim
67 words
A process as claimed in claim 1, comprising the additional steps of conveying said at least two-layer fibre web through a press section for additional dewatering of the fibre web; and recirculating the water being removed from said fibre web in said press section to said washing process and therein using it for substituting the original, BOD substances containing, suspension water in said second fibre suspension flow.
Claim 3
Dependent Claim
56 words
A process as claimed in claim 1, wherein the water being removed from said first fibre suspension flow in said first sheet forming stage and the original, BOD substances containing, suspension water being exchanged in said second fibre suspension flow in said washing process is recirculated for use in the preparation of said initial fibre-stock suspension.
Claim 4
Dependent Claim
79 words
A process as claimed in claim 1, wherein said second fibre suspension flow is conveyed after said washing process to two or more additional sheet forming stages for the forming and dewatering of two or more additional fibre layers, which are joined with said first fibre layer formed and dewatered in said first sheet forming stage to a multi-layer fibre web in such a manner that said first layer will form a central layer in said multi-layer fibre web.
Claim 5
Dependent Claim
54 words
A process as claimed in claim 5, wherein said multi-layer fibre web is conveyed to a press section for additional dewatering and said first fibre layer is dewatered in said first sheet forming stage to a water content not exceeding the total water content of said multi-layer fibre web when leaving said press section.
Claim 6
Dependent Claim
23 words
A process as claimed in claim 1, wherein said additional fibre layer is formed and dewatered in contiguity with said first fibre layer.
Claim 7
Dependent Claim
53 words
A process as claimed in claim 7, wherein said first fibre layer is dewatered from both sides at the same time in said first sheet forming stage, whereas said additional fibre layer formed in said additional sheet forming stage is dewatered substantially only from the side facing away from said first fibre layer.
Claim 8
Dependent Claim
244 words
Apparatus for the manufacture of fibre sheet products, in particular paper, comprising a first sheet forming section for the forming and dewatering of a first fibre layer; at least one additional sheet forming section for the forming and dewatering of at least one additional fibre layer; means for joining sAid first fibre layer from said first sheet forming section and said additional fibre layer from said additional sheet forming section to a multi-layer fibre web; a press section for the dewatering of said multilayer fibre web; means for receiving a flow of an initial fibre-stock suspension and dividing this flow into at least a first and a second fibre suspension flow; means for washing a fibre suspension by substitution of new water for the original water in the suspension; means for conveying said first fibre suspension flow to said first sheet forming section; means for conveying said second fibre suspension flow to said washing means and for conveying said second fibre suspension flow after being washed in said washing means to said additional sheet forming section; means for collecting backwater from said first sheet forming section and original suspension water being exchanged for new suspension water in said washing means and conveying it to said means for receiving and dividing the initial fibre-stock suspension; and means for collecting backwater from said additional sheet forming section and said press section and conveying this backwater to said washing means to be used as washing water therein.
Claim 9
Dependent Claim
39 words
Apparatus as claimed in claim 9, wherein said additional sheet forming section is adapted to form and dewater said additional fibre layer in contiguity with said first fibre layer being formed and dewatered in said first sheet forming section.
Claim 10
Dependent Claim
46 words
Apparatus as claimed in claim 9, comprising at least two such additional sheet forming sections for the forming and dewatering of one additional fibre layer each in contiguity with opposite sides of said first fibre layer being formed and dewatered in said first sheet forming section.
Claim 11
Dependent Claim
102 words
Apparatus as claimed in claim 9, wherein each sheet forming section comprises a rotatable forming roll, two endless wires extending one upon the other along a portion of the circumference of the cylindrical surface of said forming roll so as to confine a nip between them at said forming roll, which nip converges in the direction of movement of said wires, and means for injecting a fibre suspension in said nip; the outermost of said two wires at the forming roll in a given sheet forming section constituting also the innermost wire at the forming roll in the next sheet forming section.
Claim 12
Dependent Claim
38 words
Apparatus as claimed in claim 12, wherein said forming roll in said first sheet forming section has an open, water-permeable, cylindrical surface, whereas said forming roll in said additional sheet forming section has a closed, impermeable, cylindrical surface.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |