US3452876A - Dewatering equipment - Google Patents

Description

July 1, 1969 M E, GINAVEN 3,452,876

DEWAT ERING EQUIPMENT Filed June 29, 1966 INVENTOR. /4 MARVIN E. GINAVEN n fwmmw l ATTORNEY July 1969 M. E. GINAVEN 3,452,876

DEWATERING EQUIPMENT Filed June 29, 196e sheet 3 of 2 INVENTOR. lMARVIN E. GINAVEN BY We Y ATTORNEY United States Patent O DEWATERIN G EQUIPMENT Marvin E. Ginaven, Springfield, Ohio, assignor to The Bauer Bros. Co., Springfield, Ohio, a corporation of Ohio Filed June 29, 1966, Ser. No. 565,038 Int. Cl. B01d 25/04, 21/02 U.S. Cl. 210-409 13 Claims ABSTRACT F THE DISCLOSURE A separator removing water and fine solids from a flowing slurry wherein a screen unit receives the slurry in a shallow, sheet-like form and is constructed variably to accelerate flow, with solids 'being subjected to successive rolling and sliding actions while an underlying layer of liquid is sheared therefrom.

This invention relates to a dewatering device for simply and economically extracting large quantities of liquid from a flowing slurry. In a :preferred embodiment it has particular advantage in application to a pulp slurry and will be so described, though not so limited.

Dewatering equipment is an essential part of any pulp refining system. -In processing wood pulp, for example, in treatment the fibrous particles are embodied in a liquid carrier to provide thereby a small percentage of the composition of a slurry so formed. The carrier may function in various manner depending on its chemical content. In any event it serves to fiow the fibers during a treatment or transition process. Thus, the carrier serves an important purpose. Nevertheless, in order to properly refine the fiber content, it is essential that a substantial portion of the carrier be removed before the fibrous particles pass through mechanical defibering equipment of various sort and size. Much special equipment and various screening devices have been devised and utilized to this end. However, the prior art equipment of this nature is either expensive, per se, uses up a lot of expensive space, has limited application or is inadequate for most effective use.

The present invention enables the substantial elimination of the problems above described. It provides a unique screening device constituing a dewatering unit which is not only economical to fabricate but capable of substitution for various types of larger and more expensive dewatering equipment which is presently in use for pulp refining.

A primary object of the invention is to provide dewatering equipment which is economical to fabricate, more eflicient and satisfactory in use, adaptable to a wide variety of applications and unlikely to malfunction.

A further object of the invention is to provide a unique screening device which is particularly advantageous for use in the treatment of fibrous pulp.

Another object of the invention is to provide a device for dewatering pulp and other slurries which is effective to shear from an applied flowing slurry a significant portion of its liquid content.

An additional object of the invention is to provide an improved unit for dewatering a flowing pulp or other slurry which incorporates means for effectively controlling the slurry flow and, in the process thereof, extracting undesirable content.

Another object of the invention is to provide dewatering equipment for pulp and like slurries characterized by a unique vertically orienting screen unit successive defined sections of which are differently inclined.

Afurther object of the invention is to provide a unique screening device for dewatering a pulp or like slurry com- 3,452,876 Patented July 1, 1969 'ice prised of successive differently inclined sections, formed so portions transverse to anticipated flow -have long arcuate deviations occurring in the line of flow.

Another object of the invention is to provide dewatering equipment for pulp slurries including a unique screen successive sections of which are differently angled and have surface contours so designed to shear a significant portion of liquid from a flowing slurry and successively induce a smooth feed of the fibrous content, a rolling thereof with stretching but minimum fiber separation land then slow sliding thereof in exit from the screen.

An additional object of the invention is to provide a dewatering unit possessing the advantageous structural features, the inherent meritorious characteristics and the means and mode of use herein described.

With the above and other incidental objects in view as will more fully appear in the specification, the invention intended to be protected by Letters Patent consists of the features of construction, the parts and combinations thereof, and the mode of operation as hereinafter describedv or illustrated in the accompanying drawings, or their equivalents.

Referring to the accompanying drawing wherein is shown one but obviously not necessarily the only form of embodiment of the invention,

FIG. 1 is a perspective view of a preferred embodiment of the invention;

FIG. 2 is a front view thereof;

FIG. 3 is a fragmentary view of a portion of the screen formation utilized in the device of FIGS. l and 2; and

FIG. 4 is a generally schematic cross sectional view of the device of FIGS. 1 and 2.

Like parts are indicated by similar characters of reference throughout the several views.

The invention embodiment here illustrated finds its support in a frame 10. The frame 10 includes three pairs of posts '11, 12, and 13, each pair being of different height. The posts 11, which are longest, form the rear corners of the frame 10 while the shortest posts 12 form its forward corners. Adjacent and spaced from their bottoms, post 11 are interconnected by a brace bar 14. Similarly posts 11 and 12 to either side of the frame are interconnected by a brace bar 15. The upper surfaces of bars 14 and 15 occupy a vcommon plane. The third pair of posts '13 seat respectively at their bottoms to the bars 15 to either side of the frame 10. The posts 13 project vertically in a relatively adjacent, spaced, parallel relation to the rear posts 11 to dispose their upper ends in a plane common to the upper ends of posts 11. The upper ends of posts 11 and 13 are interconnected by a rectangular frame of bars 16. The posts 13 are further braced by a bar 17 Iat a level adjacent their upper ends, spaced below and parallel to a bar 16. To either side the basic frame is completed by a bar 18 which extends between and connects the upper ends of posts 12 and 13.

Connected to nest in the rectangular opening defined by the upper ends of the posts 11 and 13 and the bars 16 is a receptacle 19 which is open at its top. The receptacle 19 has a depth to extend considerably below the level of the bar 17. The front wall 20 of this receptacle which disposes between the posts 13 has its upper portion displaced and an extension 21 thereof bent forwardly and down over the bar 17, the angle of displacement being in this instance in the neighborhood of tov 150.

A bracket 22 fixed to depend from the bar 16 immediately above the bar 17 has a portion which projects horizontally in a direction forwardly from the posts 13 and terminates in a short vertically dependent portion 23. The portion 23 mounts a pair of transversely aligned screws 24 projecting through vertically elongated slots 25 in the upper end of a control plate 26. The plate 26 depends vertically in a plane parallel to the front wall 20 of the receptacle 19 and terminates adjacent the inclined surface of the extension 21, towards its bottom, in a short forwardly projected right angled ledge portion 27 which is coextensive with its lower edge.

Wall elements 28 fixed at either side of the frame 10 form a broad channel, respectively disposed immediately adjacent to either side of the extension 21 and control plate 26. They respectively mount on a bar 18 and itS supporting posts 12 and 13.

Fixed to each of the opposed inner faces of the Wall elements 2S is a support member 29 presenting a ledge portion projecting inwardly of the side of the frame at right angles thereto. The ledge portions have successively adjacent relatively inclined sections 30, 31 and 32. The uppermost section 30 follows the angle of the extension 21 on the receptacle 19. The intermediate section 31 is deviated from this angle, preferably about 10, in an upward sense, and section 32 is further deviated an additional 10, more or less, in the same sense. At their lower ends the wall elements 28 are transversely bridged by a closure plate 33 mounting an abutment bracket 34. The bracket 34 serves as an abutment for the lower ends of the support members 29.

It should be noted that the members 29 are adjustably fixed in transverse alignment, to the adjacent faces of the wall elements 28, by means of slotted portions 35 which accommodate clamping screws 36. Thus the angles of vertical inclination of the ledge sections 30-32 may be readily varied, within defined limits, to suit the particular application.

The ledge portions of the members 29 are bridged by a transversely disposed screen unit 37 which extends longitudinally thereof from end to end. The screen 37 is comprised of integrated sections 38, 39 and 40 which respectively seat to and conform with the relative inclinations of ledge portions 30, 31 and 32. The base of the screen is constituted by longitudinally extended, transversely spaced bars 41 bridge to their upper ends by a transverse bar 42 and similarly to their lower ends by a bar 43. Intermediate the lbars 42 and 43, the bars 41 are transversely bridged by spaced bar elements 44. It is a characteristic of elements 44 that between bars 41, from end to end, they depart from an anticipated straight line configuration to form a single curve having a shallow contour, the curve projecting in the direction of anticipated flow.

Noting FIG. 1 of the drawings, -when observing the operating surface of the screen 37, there are bends which sharply define the relative inclination of successively adjacent screen sections 38, 39 and 40. Moreover, there occurs in transversely disposed bars 44, between those portions which overlie and connect to uderlying bars 41, a gentle, smoothly arcuate displacement thereof from a straight line and in the sense of an anticipated flow.

In the preferred embodiment of the invention the extension 21 is bent downwardly fom a vertical about 150 and the screen sections 30, 31 and 32 dispose relative the same reference plane at angles thereto of about 150, 140, and 130, in that order. Optimal performance, in the described application, has been found to occur when there is a variation from these angles of little more than about 10, in either direction.

The `bottom edges of the wall elements 28 are transversely bridged by a plate 45 having an opening 46 located adjacent the lower or base edge of the closure plate 33. This opening is defined by a rearwardly projecting tube 47 which provides an outlet from the drain chamber 48 beneath the screen 37.

It is noted that the receptacle 19 has a normally plugged drain opening 50 which serves an obvious purpose.

For an understanding of the invention, its utility and important advantages, let us consider the embodiment just described as applied to the dewatering of dilute pulp slurry containing one to three percent of fibrous solids. The slurry, delivered from a preliminary pulp processing 4 unit, must be thickened prior to transmittal, for example, to a Helipress. Only in this Way can the press function optimally at relatively low cost and produce quality results. The slurry is fiowed to the receptacle 19 to lill its depth to the level of the front wall 20. With a continued delivery of the slurry, an overflow occurs in a uniform manner, coextensively with the transverse extent of the downwardly inclined extension 21. The ydepth of the receptacle 19 provides that heavy and undesirable solids contained in the slurry will drop, under the influence of gravity, to its bottom. Accordingly, when the slurry flows over the extension 21, it has been relieved of particularly undesirable content.

As the slurry moves down the extension 21, the control plate 26 functions to cause the flow to contour to a smooth sheet-like form. The flange 27 has a configuration to avoid either the cutting of the contained fibers or the disturbing of the sheet-like form of the slurry flow. As the slurry moves from the extension 21 to the screen, there is no disturbance to the flow since both the extension 21 and screen section 38 are at the same angle to a vertical.

The sheet of slurry accelerates over the screen section 38 in a transversely coextensive relatively uniform manner and in a non-turbulent ow. It is to be noted the bars 44 provide an operating surface devoid of projections. The uniformity of fiow is aided by the contour of the bars 44, the shallow arcuate form of which inhibits channelling along the areas of the support bars 41. This feature has been distinctively proven in test installations.

'In movement over the screen section 38 the sheet of slurry achieves a considera-ble flow velocity. The nature of this flow is such to produce a layered effect within the slurry, the contained solids lifting to its upper surface and only limited fines dropping to the lower surface adjacent the screen. Thus, the under layer of the flowing slurry is, in the main, liquid carrier. The shallow arcs of the bars 44 function further to effect a shearing action on the underside of the slurry flow causing a substantial portion of the liquid carrier to exit through the screen to the chamber 48 there'below.

The relative length of the section 38 depends on the particular application. Where the pulp products in the slurry have a low freeness and are hard to drain, the section 38 `will be made considerably longer than the sections 39 and 40.

In moving from the section 38 to the sharply defined and relatively angled section 39 the slurry has imposed thereon an abrupt though gentle change in vertical direction. This change is such to cause the fibrous content of the slurry to be inherently rolled. 1n the movement thereof, the fibers stretch while preserving themselves in well defined bundles. Tests have established that the angle of inclination of the screen sections and the form of the related bars 44 mutually cooperate in producing the noted effect. Of course, in moving over the section 38 an additional layer of liquid carrier is sheared from the fiowing slurry and quickly displaced to the drain chamber 48.

By the time the slurry arrives at the sharply defined screen section 40, it is considerably thickened. In moving over the section 40 the thickened slurry, including optimally formed fiber bundles, has a slow sliding movement, induced in part by the inclination of the screen at this point. Bars 44 shear further amounts of liquid at this stage and the resultingly thickened slurry slides over the lower end of the screen 37 to a suitable receptacle (not shown).

The liquid which has been removed from the slurry is induced naturally, by the inclination of the closure plate 33, to move to and through the outlet 47 for disposal in a manner that suits the particular application.

The invention embodiments, as illustrated, are thus capable of quickly, effectively and economically thickening a slurry. In the dewatering process they have been found to remove line sand, dirt, and grit, as well as heavy foreign particles. As applied to a fibrous pulp slurry, they create a slurry movement and influence a shearing of the slurry such that the extracted liquid contains a minimum of fines. Moreover, the manner in which the screen operates on fibrous pulp to roll and stretch the pulp to a substantially improved form, without undue separation, is such to facilitate its further treatment in mechanical defiberizing equipment.

The efficiency of the invention embodiment here illustrated has been well established by tests. For example, where the pulp slurry was delivered to the screen 37 with a solids content of from .6% to 1%, the resultant product proved to have a solids content from 2.2% to 2.5%. It will -be therefore obvious that the invention provides a highly efficient and economical means for facilitating high consistency refining.

The relative angles of the defined screen sections will depend on the particular application. In reference to a fibrous pulp refining, as indicated, a `difference in inclination between screen sections produces excellent results.

It has been proven that the compact screen unit above described, the operating surfaces of which are fiat, functions uniquely and in a manner to enable the embodiments thereof, which are `completely stationary, to replace more expensive and much more bulky dewatering equipment.

Embodiments will function equally on granular and other materials. In most cases they are capable of removing, in a single pass, about 50% of a liquid carrier, the extracted liquid having a minimum residual content of entrained solids.

The versatility of the invention embodiments is quite clear when considering the following examples of their effective use:

(A) To thicken and classify pulp slurries ahead of press-refiner systems for rejects, screenings, chip ground wood refining, or semi-chemical refining.

(B) To increase freeness and thicken pulp stock for vacuum deckers.

(C) To salvage fibers in press efliuent and/or other fiows carrying fibers of useable quality.

(D) To screen fibers as previously done with flat or rotary screens having moving parts.

In any event the invention provides such dewatering equipment as will enable the inexpensive expansion of an overall plant capacity and the operation of such plant in a more economical manner.

From the above description it will be apparent that there is thus provided a device of the character described possessing the particular features of advantage before enumerated as desirable, but which obviously is suscepti-ble of modification in its form, proportions, detail construction and arrangement of parts without departing from the principle involved or sacrificing any of its advantages.

Having thus described my invention, I claim:

1. A dewatering unit for extracting liquid `from a flowing slurry including a screen -unit characterized by successively adjacent longitudinally extending sections each having defined limits, each of said sections being downwardly inclined and adjacent of said sections being relatively inclined, each successive section forming `a lesser angle with a horizontal and the edges of adjacent sections merging with one another to `define a continuous screen surface over which the slurry flows in smooth transition through successive changes of direction in the same sense, said screen sections including longitudinally extending transversely spaced support elements and, in overlying relation thereto, transversely extending longitudinally spaced elements which in the areas intermediately of adjacent of said transversely spaced support elements form a single shallow arc which projects in the direction of fiow.

2. A dewatering unit as in claim 1, characterized by said screen sections being comprised of longitudinally extending transversely spaced support elements and, in overlying relation thereto, transversely extending longitudinally -spaced elements which in the areas intermediately of said transversely spaced support elements form a single shallow arc which projects in the direction of flow.

3. A dewatering unit as in claim 1 wherein the operating surface of the uppermost screen section has a displacement from a vertical on the order of to 150 and said uppermost screen section has an operative length which is -greater than that of the `following section.

4. A dewatering unit as in claim 1 wherein adjacent of said sections have a relative angular displacement on the `order of 10.

5. A dewatering unit as in claim 1 characterized in that means are connected to provide a receptacle in advance of said screen unit and there are means forming a downwardly inclined transition surface which interconnects said receptacle with the upper end of said screen unit, said transition surface and the section of said screen unit which is adjacent thereto being transversely coextensive.

6. A dewatering unit as in claim 5 characterized by said receptacle having a depth to store a quantity of slurry and providing means for a uniform overflow to move therefrom by way of said transition surface to said screen, and means mounting in an overlying spaced relation to said transition surface formed to contour said slurry which moves down said transition surface to a generally uniform, non-turbulent sheet-like flow.

7. A dewatering unit for a pulp or like slurry comprising a screen unit consisting of successively adjacent sharply defined sections the operating surfaces of which are flat, successive sections being relatively inclined and so formed and related to be successively characterized by means providing a transversely coextensive uniform feed, a rolling of the solid content `of the slurry, inducing a fiber concentration, and a sliding of elongate fiber bundles so formed over a terminal section of said screen, said means including underlying supports and at their operating surfaces transverse screen elements having between said supports a single downward curve in the direction of flow over the screen, said elements being operative to shear from a fiowing slurry a substantial portion of its liquid content in movement thereof from one end of said screen unit to the other.

8. A screen unit as in claim 7 for the flowing of a slurry thereover for separation of liquids by passage through screen openings, the screen unit having a continuous smooth flow surface of substantial open area, said screen unit being comprised of sections each -bent angularly on the order of 10 relative to preceding and succeeding sections, and means for mounting said screen unit in an angular position whereby slurry deposited thereon at the upper end of said flow surface descends by gravity over said surface and undergoes successive changes of direction as successive sections are encountered.

9. A screen unit according to claim 8, characterized in that successive sections of said screen are bent successively closer to a horizontal whereby changes in direction of the flowing slurry are accompanied by successively greater decelerating infiuences.

10. A screen unit for the flowing of a slurry thereover for separation of liquids by passage through screen openings, including a screen having a continuous smooth flow Surface of substantial open area, said screen being comprised of sections each bent angularly relatively to preceding and succeeding sections, and means for mounting said screen in an angular position whereby slurry deposited thereon at an upper end of said fiow surface descends by gravity over said surface and undergoes successive changes of direction as successive sections are encountered, said screen being comprised of laterally spaced apart supports of longitudinal extent between which are bent rods forming a single curve between adjacent supports, said rods being in a nested spaced relation in a longitudinal sense with each adjacent pair of rods defining a single arcuate slot therebetween, said slots constituting the open area of the screen.

11. A screen unit according to claim 10, characterized in that said rods are curved in the direction of flow over the screen surface, the curving portions of said rods developing side forces upon the moving7 slurry Washing the slots for an effective self cleaning action.

12. A dewatering unit for a pulp or like slurry comprising a screen unit consisting of successively adjacent sharply dened sections, the operating surfaces of which are at, successive sections being relatively inclined and so formed and related to -be successively characterized by means providing a transversely coextensive uniform feed, a rolling of the solid content of the slurry, inducing a fiber concentration, and a sliding of elongate ber bundles so formed over a terminal section of said screen, said means providing a ow surface which is devoid of projections and being formed therein with slots which are transversely elongated and curved to project in the direction of a slurry ow thereacross.

13. A dewatering unit as set forth in claim 12 characterized by means defining said slots providing they be so curved as to develop side forces upon the slurry which move thereacross so as to wash the slots with an effective self-cleaning action.

References Cited UNITED STATES PATENTS 2,572,869 10/1951 Koonce et al 210-456 X 2,142,600 1/1939 Bixby 209-393 2,703,649 3/1955 Cheyette 209-394 X 2,790,5521 4/1957 Symons 209-395 2,896,785 7/1959 Fontein 209-393 X 2,600,508 6/1952 Lehman et al 209-354 2,916,142 12/1959 Fontein 209-274 3,116,239 12/1963 Bixby 210-499 X 3,259,244 7/1966 KalZo etal 209-281 X FOREIGN PATENTS 725,264 3/1955 Great Britain.

OTHER REFERENCES German printed application 1,004,111 (1957).

REUBEN FRIEDMAN, Primary Examiner.

F. A. SPEAR, JR., Assistant Examiner.

U.S. Cl. X.R. 210-433, 456

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