Patent US3921918A successfully refreshed from Google Patents.
US3921918A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Mechanical refining of fiber material including steam recycle
Assignee: SCA Development AB
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Filing: 1974-07-17
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Granted: 1975-11-25
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Expires: 1994-07-17
Abstract
Abstract Refiner pulp is prepared by the steps of pretreating fibrous material with steam in a preheater followed by the step of refining the steam-treated material in a disc refiner whereby steam is developed, and at least a part of the developed steam is conducted back to the preheater for maintaining desired pressure and temperature conditions in the preheater.
Inventors
- 👤 Viking Per Peterson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:20
CPC Classifications
D; D21; D21D; D21D1/00; D21D1/20; D21D1/30
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
140 words
IN A METHOD OF TREATING FIBER MATERIAL INVOLVING THE STEPS OF FIRST PREHEATING THE MATERIAL WITH STEAM UNDER ELEVATED TEMPERATURE AND SUPERATMOSPHERIC PRESSURE IN A PREHEATER SPACE AND THEN FEEDING THE MATERIAL AS A STREAM INTO A DISC WHICH COMPRISES A CARBURIZED FRICTION BEARING SURFACE FORMED ON SAID STEEL REFINER FOR REFINING THE MATERIAL DURING ITS OUTWARD PASSAGE FROM BETWEEN THE GRINDING DISCS OF THE DISC REFINER DURING BEARING PIN; BLY, THE IMPROVEMENT COMPRISING SAID BALL BEARING MEANS A BORONIZED SURFACE FORMED ON SAID CARBURIZED BEARING INCLUDING A RACE COMPRISING POLYURETHANE AND AN ACETAL RESIN. WHICH PASSAGE STEAM AT SUPERATMOSPHERIC PRESSURE IS DEVELOPED, THE IMPROVEMENT CONSISTING OF CONDUCTING PART OF SAID SURFACE; SAID CARBURIZED SURFACE BEING HARDENED AND TEMPERED BY DEVELOPED PRESSURIZED STEAM BACK INTO THE PREHEATER SPACE IN ORDER TO MAINTAIN THE TEMPERATURE AND PRESSURE IN SAID PREHEATER SPACE.
Claim 2
Dependent Claim
140 words
IN A METHOD OF TREATING FIBER MATERIAL INVOLVING THE STEPS OF FIRST PREHEATING THE MATERIAL WITH STEAM UNDER ELEVATED TEMPERATURE AND SUPERATMOSPHERIC PRESSURE IN A PREHEATER SPACE AND THEN FEEDING THE MATERIAL AS A STREAM INTO A DISC WHICH COMPRISES A CARBURIZED FRICTION BEARING SURFACE FORMED ON SAID STEEL REFINER FOR REFINING THE MATERIAL DURING ITS OUTWARD PASSAGE FROM BETWEEN THE GRINDING DISCS OF THE DISC REFINER DURING BEARING PIN; BLY, THE IMPROVEMENT COMPRISING SAID BALL BEARING MEANS A BORONIZED SURFACE FORMED ON SAID CARBURIZED BEARING INCLUDING A RACE COMPRISING POLYURETHANE AND AN ACETAL RESIN. WHICH PASSAGE STEAM AT SUPERATMOSPHERIC PRESSURE IS DEVELOPED, THE IMPROVEMENT CONSISTING OF CONDUCTING PART OF SAID SURFACE; SAID CARBURIZED SURFACE BEING HARDENED AND TEMPERED BY DEVELOPED PRESSURIZED STEAM BACK INTO THE PREHEATER SPACE IN ORDER TO MAINTAIN THE TEMPERATURE AND PRESSURE IN SAID PREHEATER SPACE.
Claim 3
Dependent Claim
24 words
The method according to claim 1, wherein the superatmospheric pressure within the preheater space is controlled by evacuating any excess steam from said space.
Claim 4
Dependent Claim
30 words
The method according to claim 1, wherein preheated material is fed from said preheater space to the disc refiner by causing the material to fall freely through a feeding chute.
Claim 5
Dependent Claim
23 words
The method according to claim 1, wherein the fibre material is heated by the steam to 105*-115*C, the steam pressure being 0.2-0.6 kg/cm2.
Claim 6
Dependent Claim
16 words
The method according to claim 1, wherein the refining is carried out in a single step.
Claim 7
Dependent Claim
15 words
The method according to claim 1, wherein the refining is carried out in two steps.
References Cited (Backward Citations)
US1922313A
Cited
US2816831A
Cited
US3238088A
Cited
US3388037A
Cited
US3414038A
Cited
US3425477A
Cited
US3773610A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-24 | 1979-05-26 | 1979-11-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-24 | 1983-05-26 | 1983-11-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-24 | 1987-05-26 | 1987-11-25 | $7700.00 | Window Closed / Lapsed |