US3441227A - Refiner feeder - Google Patents

Description

" c. o. FISHER REFINER FEEDER Iof2 - Sheet File d Dec; 22, 1966 Qm Yww MM 7 Mm H w n \IJ R. A Q, n W W 9. wm m INVENTORI CHESTER DONALD FISHER ATT Y5 C. D. FISHER REFINER FEEDER April --29, 1969 Sheet fined Dec. 22, 1966 F'IGB.

INVENTORI. CHESTER DONALD FISHER IIW/WMv 4 W ATTYS.

United States Patent US. Cl. 241-247 9 Claims ABSTRACT OF THE DISCLOSURE A throat screw feeder for use with disc type paper pulp refiners in refining high consistency stock characterized by a ribbon-type screw rotated 'to advance the stock into the refiner throat while permitting a steam backfiow from the refiner within the ribbon screw without interference with the stock flow.

The present invention relates generally to stock feeding devices for disc-type paper pulp refiners and relates more particularly to a refiner feeder particularly adapted for feeding high consistency groundwood stock into a disc refiner.

It has been conventional practice to utilize a helical feed screw to advance unrefined stock from a supply reservoir into the refining zone of a disc-type paper pulp refiner. The conventional feeder utilizes a solid feed screw to advance the stock into the refiner and this construction has worked satisfactorily with low consistency stock, there being a sufficiently high stock water content to dissipate the heat generated during the refining operation without the formation of troubesome quantities of steam.

However, in groundwood refining wherein the stock has a very low water content, the water present is transformed into steam by the refining heat and a sufficient steam pressure forms to interfere with the stock feed. Although much of the steam passes out of the refiner with the refined stock, a substantial amount of steam discharges back through the refiner feed screw and; with conventional solid feed screws, interrupts the chip flow to the refiner. The feed interruptions cause severe variations in the refiner load which have a serious detrimental effect on the pulp quality. In addition, the load variations result in severe surges by the refiner drive motor which may be in order of several hundred horsepower with the result that the refiner must be operated at an average load sufiiciently below the motor capacity to allow for the power surges. The present refiner feeder has thus been developed to improve the pulp quality and to allow efficient full power operation of the refiner when high consistency stock is being processed.

In the present feeder, provision is made for the escape of steam back through the feeder by employing a high speed ribbon feeder, the high speed operation of which holds the stock around the periphery of the feeder housing, permitting the steam to flow back through the open central region of the feeder along the ribbon drive shaft. By removing the steam from the feeder at a point axially outward of the stock input, the steam does not interfere with the stock flow and a uniform feed rate can be attained to permit a uniform high quality refining operation at full refiner power.

In View of the above it can be understood to be a first object of the present invention to provide an improved refiner feeder for disc-type refiners particularly adapted for refining high consistency stock without feed interruptions.

A further object of the invention is to provide a refiner feeder as described having means permitting steam escape from the refiner through the feeder without interfering with stock inflow to the refiner.

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Another object of the invention is to provide a refiner feeder as described adapted to provide an improved pulp quality and refiner efficiency.

A still further object of the invention is to provide a refiner feeder as described of a sample, efiicient construction which may be economically manufactured and maintained.

Additional objects and advantages of the invention will be more readily apparent from the following detailed description of an embodiment thereof when taken together with the accompanying drawings in which:

FIG. 1 is a side elevational view of a refiner feeder in accordance with the present invention showing the feeder mounted on a disc-type refiner, the refiner feeder being shown in section and the refiner being shown partly in section and being partly broken away to indicate the stock flow path therein;

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1; and

FIG. 3 is a partial plan view of the refiner looking into the stock inlet and steam discharge passages.

Referring to the drawings, FIG. 1 shows a refiner feeder 10 in accordance with the present invention mounted on a disc-type refiner 12 for advancing high consistency stock thereto. The refiner 12 of conventional construction, includes the casing 14 within which the rotor 16 carrying refining plates 18 is mounted for rotation on the shaft 20. The feed end of the casing is closed by the swing head 22 which supports the fixed refining plates 24, the swing head being secured to the casing by bolts 26 during operation of the refiner. Unrefined stock is delivered axially by the feeder through the circular aperture 28 in the swing head into the throat 29 of the refiner and is driven by centrifugal force through the refining zone 30 between the refining plates into the peripheral region 32 of the casing 14 and through the refiner outlet 34.

The present refine-r feeder 10 includes a housing means 36 comprising a cylindrical screw housing 38 coaxial with the refiner and bolted to the swing head 22 by means of the flange 40 having spaced bolt holes 41 therein as shown in FIG. 2. The swing head aperture 28 and the screw housing 38 are of the same diameter to permit a smooth flow of the stock into the refiner. A ribbon feed screw 42 is mounted on coaxial shaft 44 in the screw housing by means of the ribbon support rods 46, the shaft being rotatably supported by bearings 48 and 50 mounted in the auxiliary housing 52 at the outer end of the screw housing. The auxiliary housing is sealed from the screw housing by means of the stuffing box 54.

The drive means for rotating the shaft 44 comprises a motor 56 mounted on the adjustable motor base 58 in the motor housing 60, the motor being connected to the shaft 44 by the belt drive 62. The housing assembly is stiffened by the diagonal braces 64 and is further supported by means of the support member 66 extending to the refiner base or the floor.

A rectangular flanged duct 68 opens into the outer end of the screw housing 38 from above and includes an axially transverse vertical partition 70 dividing the duct into a stock inlet passage 72 at the inner side of the duct and a steam discharge passage 74 at the outer side of the duct. The flanged duct 68 is adapted for connection with a source of unrefined stock and means for disposing of the surplus steam generated in the refiner.

At the inner end of the feeder shaft 44 closely adjacent the refiner throat are mounted a plurality of inner and outer paddles 76 and 78 adapted to expedite stock flow into the refiner throat. The inner paddles 76 include wing portions 80 conforming with the refiner throat configuration to further the stock feeding action in this region.

The ribbon screw 42 has an external diameter sufficiently smaller than the internal diameter of the screw housing 38 to provide a clearance 82 therebetween which prevents the binding of wood chips between the ribbon and the housing wall. The interior diameter of the ribbon screw is substantially larger than the diameter of the shaft 44 thus providing an annular passage 84 for steam backflow from the refiner throat 29 to the steam discharge passage 74, the rotating rods 46 having a negligible retarding effect on the escaping steam.

For operation of the refiner feeder, the flanged duct 68 is connected to a source of high consistency stock and means provided to exhaust steam from the steam discharge passage 74. With the refiner operating to rotate the rotor 16, the motor 56 is operated to drive the shaft 44 and attached feed screw 42 and paddles 76 and 78 at a relatively high speed. A typical speed for example with a 14 inch ribbon screw having approximately a 3 inch pitch would by 500 r.p.m. for feeding stock to a 42 inch refiner. The size and pitch of the screw and speed of rotation would, of course, depend on the capacity of the refiner and the consistency of the stock being fed thereto.

The stock entering through the stock inlet passage 72 is picked up by the ribbon screw 42 and, due to the high speed rotation of the screw, is thrown by centrifugal force outwardly against the inner wall of the screw housing 38 and is advanced therealong into the paddles 78 and 76 and into the refiner throat 29 whereupon it is advanced by the centrifugal action of the rotor 16 across the refining plates in the refining zone 30 and out of the refiner through the outlet 34. Steam generated in the refining zone 30 passes in part out through the outlet 34 but a substantial amount of steam backs up into the refiner throat and into the feeder. With the present feeder construction, due to the use of a high speed ribbon screw which throws the stock to the outside of the screw housing, the annular steam escape passage 84 is kept substantially free of stock permitting a counterfiow of steam from the throat 29' along the shaft 44 of the feeder to the outer end of the screw housing 38 and out through the steam discharge passage 74 in the duct 68. In this manner the escaping steam does not interfere with the stock inflow and the stock is advanced into the refiner throat without interruption.

As an example of the refiner efiiciency improvement provided by the present refiner feeder, with a conventional solid screw feeder employed with a 2,000 HP refiner for refining high consistency stock, the inter-ruptions of the stock flow by the steam backflow caused power surges in the range of 200-300 HP with the result that the refiner could only be operated at an average load in the range of 1800-1850 HP. It can thus be appreciated that steam interference with stock flow in a conventional refiner feeder can result in the loss of as much as 10% of the refiner capacity. Even more serious is the problem of poor quality pulp resulting from the interrupted flow conditions.

With the present ribbon type feeder, stock flow interruptions caused by steam backflow are entirely eliminated and the refiner may be run at full power with high consistency stock to produce a uniform quality pulp.

Manifestly, changes in details of construction can be effected by those skilled in the art without departing from the spirit and the scope of the invention as defined in and limited solely by the appended claims.

1 claim:

1. A feeder for advancing high consistency stock into the throat of a disc-type refiner comprising housing means communicating with the refiner throat, a ribbon screw rotatably supported within said housing means, means for driving said ribbon screw in rotation, 21- stock inlet passage in said housing separate from said stock inlet passage, and a steam discharge passage in said housing, said ribbon screw being adapted to advance high consistency stock from said stock inlet passage to the refiner throat while permitting steam backfiow from the refiner to pass within said ribbon screw from the refiner throat to said steam discharge passage.

2. A feeder as claimed in claim 1 wherein said ribbon screw is axially aligned with the refiner axis.

3. A feeder as claimed in claim 2 wherein said steam discharge passage is located axially outwardly from said stook inlet passage.

4. A feeder for advancing high consistency stock into the throat of a disc-type refiner comprising a cylindrical screw housing communicating with the refiner throat and axially aligned with the refiner axis, a shaft coaxially journaled for rotation within said screw housing extending substantially the full length of said housing, a ribbon screw mounted coaxially on said shaft with the inner diameter thereof spaced from said shaft, means for driving said shaft and ribbon screw in rotation, a stock inlet passage in said housing, and a steam discharge passage in said housing separate from said stock inlet passage, said ribbon screw being adaped to advance high consistency stock from said stook inlet to the refiner throat while permitting steam backflow from the refiner to pass between said ribbon screw and said shaft from the refiner throat to said steam discharge passage.

5. A feeder as claimed in claim 4 wherein said steam discharge passage is located axially outwardly from said stock inlet passage.

6. A feeder as claimed in claim 4 including a plurality of paddles on the inner end of said shaft adjacent the refiner throat for directing and distributing stock into the refiner.

7. A refiner as claimed in claim 4 wherein the outer diameter of said ribbon screw is smaller than the inner diameter of said screw housing to provide a sufficient clearance therebetween to prevent binding and jamming of the stock flow.

8. A refiner as claimed in claim 4 including a plurality of radial ribbon screw support rods on said shaft for supporting said ribbon screw in spaced relation from said shaft.

9. A feeder as claimed in claim 4 wherein said means for driving said shaft and ribbon screw in rotation is adapted to rotate said shaft and screw at a suflicient speed to maintain the stock flow by centrifugal force in the radially outer regions of the screw housing thereby substantially freeing the regions adjacent said shaft from stock flow and permitting steam backflow to pass freely therethrough.

References Cited UNITED STATES PATENTS 1,608,200 11/1926 Cheyne 24l247 X 2,481,775 9/1949 Olfenhauser 241-047 X 3,077,007 2/1963 Coghill 241-247 X LESTER M. SWINGLE, Primary Examiner. D. G. KELLY, Assistant Examiner.

2 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,441,227 Dated April 29, 1969 Inventor(s) Chester Donald Fisher It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

r- Column 3, line 17, change "by" to ---be-. I

Column 4, lines 3 and 4, cancel "separate from said stock inlet passage"; line 5, after the comma insert --separate from said stock inlet passage--.

SIGNED AND SEALED OCT 2 l 1969 (S Anew nun-1m E. saaumm. Jn. Attesting Officer commissioner of Patent!

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