US3849302A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for screening paper fiber stock
Assignee: Black Clawson Co
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Filing: 1972-09-12
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Granted: 1974-11-19
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Expires: 1992-09-12
Abstract
Abstract In screening apparatus for paper fiber stock incorporating a cylindrical slotted screen member having generally axially extending slots and a rotor supporting vanes movable in the supply chamber, the circumferential spacing of the slot is greater than the average fiber length of the stock being screened, the rotor vanes are spaced from the screen member by a substantial distance (one-eighth to one-half inch) to establish a tubular layer of stock of corresponding radial thickness adjacent the screen member, the rotor is operated at high speed to develop strong hydraulic shear forces in the tubular layer of stock causing tangential orientation of predominantly two-dimensional contaiminant particles, and the stock is continuously recirculated in the supply chamber to prevent undue increase in the consistency of the stock in the tubular layer, thereby providing for high quality screening at high consistencies (as much as 5%) and high throughput rates.
Inventors
- 👤 P Seifert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:20
CPC Classifications
D; D21; D21D; D21D5/00; D21D5/02; D21D5/06
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
277 words
The method of screening a dilute suspension of paper fiber stock, comprising the steps of a. continuously supplying the stock to one end of an annular supply chamber having as one wall thereof a cylindrical screen member having multiple slots therethrough extending generally parallel with the axis thereof, b. maintaining a pressure difference from said supply chamber to the accepts side of said screen member to cause passage of accepted stock through said slots, c. causing the stock in said supply chamber to form a tubular layer of substantial thickness and of substantially the same length as said screen member immediately adjacent the surface of said screen member in said supply chamber, d. continuously rotating vane means in said supply chamber in a circular path adjoining said tubular layer at a sufficiently high speed to create a substantially tangentially oriented steady hydraulic shear field in said tubular layer of stock with shear rates sufficiently high to cause elongated contaminant particles to be aligned generally tangentially of said screen member and thereby to flow past rather than through said slots, e. said path being located in a radially intermediate position in said supply chamber and said vane means being spaced angularly from each other within said path to provide for circulation of stock between said tubular layer and the space on the opposite side of said path from said tubular layer by way of the gaps between said vane means, f. continuously removing from the other end of said screen chamber a portion of said stock including such contaminant particles, and g. continuously recirculating stock from said other end of said supply chamber to said one end thereof.
Claim 2
Independent Claim
277 words
The method of screening a dilute suspension of paper fiber stock, comprising the steps of a. continuously supplying the stock to one end of an annular supply chamber having as one wall thereof a cylindrical screen member having multiple slots therethrough extending generally parallel with the axis thereof, b. maintaining a pressure difference from said supply chamber to the accepts side of said screen member to cause passage of accepted stock through said slots, c. causing the stock in said supply chamber to form a tubular layer of substantial thickness and of substantially the same length as said screen member immediately adjacent the surface of said screen member in said supply chamber, d. continuously rotating vane means in said supply chamber in a circular path adjoining said tubular layer at a sufficiently high speed to create a substantially tangentially oriented steady hydraulic shear field in said tubular layer of stock with shear rates sufficiently high to cause elongated contaminant particles to be aligned generally tangentially of said screen member and thereby to flow past rather than through said slots, e. said path being located in a radially intermediate position in said supply chamber and said vane means being spaced angularly from each other within said path to provide for circulation of stock between said tubular layer and the space on the opposite side of said path from said tubular layer by way of the gaps between said vane means, f. continuously removing from the other end of said screen chamber a portion of said stock including such contaminant particles, and g. continuously recirculating stock from said other end of said supply chamber to said one end thereof.
Claim 3
Dependent Claim
27 words
The method defined in claim 1 wherEin the circumferential spacing between adjacent said slots is substantially greater than the average fiber length in the furnish being screened.
Claim 4
Dependent Claim
28 words
The method defined in claim 1 wherein the circumferential spacing between adjacent said slots is such that the range of slots per inch is substantially two to seven.
Claim 5
Dependent Claim
23 words
The method defined in claim 2 wherein the width of individual said slots is in the range of approximately .003 to .030 inch.
Claim 6
Dependent Claim
21 words
The method defined in claim 2 wherein the consistency of said stock is in the range of substantially 2 to 5%.
Claim 7
Dependent Claim
25 words
The method defined in claim 2 wherein the thickness of said tubular layer of stock is in the range of substantially one-eighth to one-half inch.
Claim 8
Dependent Claim
36 words
The method defined in claim 1 wherein said shear field is created by vane means rotating in said supply chamber at relatively high speed in the range of substantially 3,000 to 12, 000 feet per minute.
Claim 9
Dependent Claim
21 words
The method defined in claim 7 wherein the consistency of said stock is in the range of substantially 2 to 5%.
Claim 10
Dependent Claim
27 words
The method defined in claim 7 wherein the circumferential spacing between adjacent said slots is substantially greater than the average fiber length in the furnish being screened.
Claim 11
Dependent Claim
25 words
The method defined in claim 9 wherein the thickness of said tubular layer of stock is in the range of substantially one-eighth to one-half inch.
Claim 12
Dependent Claim
255 words
Screening apparatus for paper fiber stock comprising: a. a housing b. means including a cylindrical screen member within said housing separating the interior thereof into an annular supply chamber and an accepts chamber on opposite sides of said screen member, c. said screen member having multiple substantially parallel slots therethrough extending generally parallel with the axis thereof, d. inlet means for supplying the stock to one end of said supply chamber for passage through said slots to said accepts chamber, e. rotor means including vanes located for movement along a circular path in said supply chamber in angularly spaced relation with each other and in a radially intermediate position in said supply chamber to provide a space in said supply chamber to be filled with stock on the opposite side of said path from said screen member, f. means maintaining said vanes a substantial radial distance from the adjacent surface of said screen member to establish a continuous tubular layer of stock adjacent said surface and of a maximum corresponding radial thickness which is connected with said space through the gaps between adjacent said vanes, g. means for driving said rotor at a rate sufficient to cause said vanes to travel at relatively high speed along said path and thereby to cause said stock layer to circulate along said screen member surface at a correspondingly high speed and also around said vanes, and h. means for continuously withdrawing a portion of the stock from the opposite end of said supply chamber from said inlet means.
Claim 13
Dependent Claim
255 words
Screening apparatus for paper fiber stock comprising: a. a housing b. means including a cylindrical screen member within said housing separating the interior thereof into an annular supply chamber and an accepts chamber on opposite sides of said screen member, c. said screen member having multiple substantially parallel slots therethrough extending generally parallel with the axis thereof, d. inlet means for supplying the stock to one end of said supply chamber for passage through said slots to said accepts chamber, e. rotor means including vanes located for movement along a circular path in said supply chamber in angularly spaced relation with each other and in a radially intermediate position in said supply chamber to provide a space in said supply chamber to be filled with stock on the opposite side of said path from said screen member, f. means maintaining said vanes a substantial radial distance from the adjacent surface of said screen member to establish a continuous tubular layer of stock adjacent said surface and of a maximum corresponding radial thickness which is connected with said space through the gaps between adjacent said vanes, g. means for driving said rotor at a rate sufficient to cause said vanes to travel at relatively high speed along said path and thereby to cause said stock layer to circulate along said screen member surface at a correspondingly high speed and also around said vanes, and h. means for continuously withdrawing a portion of the stock from the opposite end of said supply chamber from said inlet means.
Claim 14
Dependent Claim
27 words
Screening apparatus as defined in claim 11 further comprising means for continuously recirculating stock from said other end of said supply chamber to said one end thereof.
Claim 15
Dependent Claim
29 words
Screening apparatus as defined in claim 11 wherein the circumferential spacing between adjacent said slots is such that the range of slots per inch is substantially two to seven.
Claim 16
Dependent Claim
29 words
Screening apparatus as defined in claim 12 wherein the circumfenential spacing between adjacent said slots is such that the range of slots per inch is substantially two to seven.
Claim 17
Dependent Claim
52 words
Screening apparatus as defined in claim 14 wherein said radial distance between said vanes and said screen member is in the range of substantially one-eighth to one-half inch, and wherein said driving means are capable of causing said vanes to travel in the range of substantially 3,000 to 12,000 feet per minute.
Claim 18
Dependent Claim
47 words
Screening apparatus as defined in claim 12 wherein the width of individual said slots is in the range of approximaTely .003 to .030 inch, and wherein the circumferential spacing between adjacent said slots is such that the range of slots per inch is substantially two to seven.
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) | 1977-11-18 | 1978-05-20 | 1978-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-18 | 1982-05-20 | 1982-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-18 | 1986-05-20 | 1986-11-19 | $7700.00 | Window Closed / Lapsed |