US3578786A

US3578786A - Discharge device for the bottom fraction at a vortex-type separator

Info

Publication number: US3578786A
Application number: US838891A
Authority: US
Inventors: Ake Karl Gustaf Cras
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-07-09
Filing date: 1969-07-03
Publication date: 1971-05-18
Anticipated expiration: 1988-05-18
Also published as: FR2012592A1; SE324144B; FI44520B; GB1252823A; DE1934878A1

Abstract

A device is provided for discharging the heavy bottom or reject fraction from a vortex-type separator and the device comprises a cylindrical vortex chamber which is connected to a bottom fraction outlet of the separator so as to receive the reject fraction therefrom in a manner producing a vortex flow in the vortex chamber. The vortex chamber is provided with an outlet port for the reject fraction and a flow-deflecting member is disposed within the vortex chamber for deflecting the vortex flow away from the circumferential wall of the vortex chamber at the location of the outlet port. The flow-deflecting member has an adjustable position in the vortex chamber so that the degree of deflection of the vortex flow from the location of the outlet port is determined by the position of the flow-deflecting member.

Description

United States Patent DISCHARGE DEVICE FOR THE BOTTOM FRACTION AT A VORTEX-TYPE SEPARATOR 5 Claims, 8 Drawing Figs.

US. Cl 210/512 B04c 5/16 Field of Search 210/84,

[56] References Cited UNITED STATES PATENTS 3,277,926 10/ I966 Skardal Primary Examiner-J. L. DeCesare Attorney-Waters, Roditi, Schwartz and Nissen ABSTRACT: A device is provided for discharging the heavy bottom or reject fraction from a vortex-type separator and the device comprises a cylindrical vortex chamber which is connected to a bottom fraction outlet of the separator so as to receive the reject fraction therefrom in a manner producing a vortex flow in the vortex chamber. The vortex chamber is provided with an outlet port for the reject fraction and a flowdeflecting member is disposed within the vortex chamber for deflecting the vortex flow away from the circumferential wall of the vortex chamber at the location of the outlet port. The flow-deflecting member has an adjustable position in the vortex chamber so that the degree of deflection of the vortex flow from the location of the outlet port is determined by the position of the flow-deflecting member.

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sum 3 033 The invention relates to a device for discharging the heavy bottom or reject fraction from a vortex type separator used for the separation of a solid material suspended in a liquid, in particular a vortex-type separator for separating a reject fraction with a comparatively high density from a cellulose fibre slurry.

Separators of this vortex type are generally provided with a discharge chamber for the heavy reject fraction, which is connected to a bottom outlet opening in a conical part of the separator. In order to prevent the reject fraction and possibly also air is resucked into the separator through its bottom outlet, the discharge chamber for the reject fraction is generally designed as a vortex or whirl chamber, which is provided with an outlet port for the reject fraction and in which the reject fraction forms a vortex flow with a comparatively high flow velocity.

During the operation of a separator provided with such a discharge device for the reject fraction, however, the control of the amount of liquid containing the reject fraction and flowing through the bottom outlet of the separator constitutes a major problem. The amount of liquid containing the reject fraction being discharged through the bottom outlet of the separator must be controlable very accurately within a wide range, as a too-large liquid flow through the bottom outlet of the separator causes loss of useful product, whereas on the other hand a too-small liquid flow through the bottom outlet of the separator causes the reject fraction to partially remain in the separator and be withdrawn therefrom together with the useful product, which will give an unsatisfactory separation. Consequently it must be possible to reduce the liquid flow containing the reject fraction being discharged from the bottom outlet of the separator through the vortex chamber down to a very small amount without any clogging of the outlet port of the vortex chamber or the discharge pipe connected to this outlet port with the solid material in the reject fraction.

It is known to locate the outlet port of the vortex chamber in the circumferential wall of the vortex chamber and provide a control valve in the discharge pipe connected to this outlet port for the control of the discharged liquid flow containing the reject fraction. In such an arrangement, however, the control valve or the discharge pipe becomes easily cloggedwhen the valve is adjusted for the most optimum discharge flow with respect to the desired separation of reject fraction and useful product. In order to eliminate this disadvantage it ha. been v suggested to locate the outlet port of the vortex chamber eccentrically in the chamber in such a way that the radial distance between the outlet port and the center of the vortex chamber can be varied. By variation of the radial distance between the outlet port and the center of the vortex chamber it is then possible to vary the amount of liquid being discharged through the outlet port. Arrangements of this type are for instance described in the US. Pat. No. 3,277,926. Although this arrangement eliminates to a substantial extent the clogging of the outlet port and the discharge pipe connected thereto with the solid material in the reject fraction, it has the very serious disadvantage, however, that heavy and hard solid particles, for instance of the type that may be found in mechanical paper pulp, will remain for a considerable time in the vortex chamber, as they will concentrate close to the circumferential wall of the vortex chamber and thus away from the outlet port which is located relatively close to the center of the vortex chamber. These hard solid particles in the reject fraction will give rise to a considerable wear of the walls of the vortex chamber.

An object of the invention is therefore to provide an improved discharge device for the discharging of a heavy reject fraction from a vortex-type separator, which discharge device makes it possible to control the amount of liquid containing the reject fraction being discharged from the separator accurately within a wide range and down to very small liquid flows without any risk for clogging of the outlet port or the discharge pipe connected thereto with the solid material in the reject fraction. The device according to the invention is of a type including a substantially cylindrical vortex or swirl chamber, which is connected to the separator so as to receive the heavy bottom fraction therefrom in a manner producing a rapid vortex flow in the vortex chamber and which is provided with an outlet port located in or close to the circumferential cylindrical wall of the vortex chamber. This discharge device according to the invention is characterized by a flow-deflecting member disposed within the cylindrical vortex chamber so as to deflect the vortex flow away from the cylindrical circumferential wall of the vortex chamber at the location of the outlet port, said flow-deflecting member having an adjustable position in the vortex chamber and the extent of the deflection of the vortex flow from the location of the outlet port being determined by the actual position of the flow-deflecting member. The more the vortex flow in the vortex chamber is deflected from the location of the outlet port the smaller the fluid pressure at the outlet port and thus the amount of fluid being discharged therethrough becomes. In this way it is possible to control the amount of fluid containing the reject fraction being discharged through the outlet port of the vortex chamber without any reduction of the cross-sectional area of the outlet port and thus without any danger of clogging the outlet port. In practice it has been found that it is possible to reduce the amount of fluid being discharged through the outlet port of the vortex chamber down to very small values and even so far that the discharge flow through the outlet port is completely interrupted without any reduction or restriction of the cross-sectional area of the outlet port being necessary.

In the following the invention will be further described with reference to the accompanying drawings, which by way of example show a number of different embodiments of the invention. In the drawings:

FIG. 1 isan axial section through a first embodiment of the invention taken along the line 1-1 in FIG. 2;

FIG. 2 is a radial section through the vortex chamber shown in FIG. 1 taken along the line ll-ll in FIG. 1;

FIG. 3 shows the adjustable vortex deflecting member in the vortex chamber shown in FIGS. 1 and 2 as seen in the direction of the arrow III in FIG. 2;

FIG. 4 shows schematically in top view a vortex chamber having a vortex deflecting member of another design;

FIG. 5 is an axial section through the vortex chamber of FIG. 4 taken along the line V-V in FIG. 4;

FIG. 6 shows in the same manner as FIG. 4 a vortex chamber provided with still another type of a vortex deflecting member;

FIG. 7 is an axial section through the vortex chamber of FIG. 6 taken along the line VII-VII in FIG. 6; and

FIG. 8 shows in the same way as FIGS. 4 and 6a vortex chamber provided with still another type of an adjustable member for deflecting the vortex flow from the outlet port of the vortex chamber.

The embodiment of the invention illustrated in FIGS. 1 to 3 includes a vortex chamber 1 constituted by a cylindrical bore in a vortex chamber body 2, which in the illustrated embodiment of the invention is arranged underneath the bottom outlet of the vortex-type separator 3. The vortex chamber 1 has an outlet port 4 located in the cylindrical circumferential wall of the chamber. A discharge pipe 5 is connected to this outlet port. During operation of the separator 3, the bottom fraction containing the reject is discharged through the bottom outlet of the separator to the vortex chamber 1, in which the fluid containing the reject fraction forms a rapid vortex flow in the direction indicated by an arrow 6 in FIG. 2. The fluid containing the reject fraction leaves the vortex chamber 1 through the outlet port 4 and the discharge pipe 5.

For the control of the amount of fluid being discharged from the vortex chamber ll through the outlet port 4 an adjustable flow-guiding member is provided in the vortex chamber ii. In the embodiment of the invention illustrated in FIGS. 1 to 3 this adjustable flow-guiding member consists of a body 7 forming a bottom in the active portion of the vortex chamber 1. This body 7 is rotatable in the vortex chamber body 2 by means of a pivot shaft 8 and a handle 9 so that the body 7 can be rotated relative to the vortex chamber 1 about the axis of the chamber. The upper side of the body 7 facing the active portion of the vortex chamber 1 has a first semicircular surface 10 which is perpendicular to the axis of the vortex chamber 1 and a second semicircular surface 11 which is inclined relative to the axis of the chamber 1. These two

semicircular surfaces

10 and 11 are joined by a triangular surface 12 which is parallel the axis of the vortex chamber 1 and extends diametrically through the vortex chamber. Normally the rotatable body 7 is given such a position in the vortex chamber 7 that the highest portion of the triangular surface 12 is located upstream of the outlet port 4 as seen in the direction 6 of the vortex flow. It is appreciated that the semicircular upper surface 11 on the body 7, which surface is inclined relative to the axis of the vortex chamber 1, will deflect the vortex flow in the chamber 1 from the circumferential cylindrical wall of the vortex chamber at the location of the outlet port 4. Consequently, the outlet port will lie in the shadow" of the triangular surface 12 on the body 7, which surface is parallel to the axis of the vortex chamber 1. The closer to the outlet port 4 the highest portion of this triangular surface 12 is located the more the fluid vortex is deflected from the outlet port 4 and the smaller the fluid pressure at the outlet port 4 and thus the amount of fluid being discharged through this outlet port will become. By rotation of the body 7 about the axis of the vortex chamber 1 it is consequently possible to control the amount of fluid being discharged through the outlet port 4 very accurately within a wide range. Thus it is possible to reduce this discharge flow down to a very small value without any reduction or restriction of the cross-sectional area of the outlet port 4. Consequently, it is not necessary to rotate the body 7 to such a position that the body covers any part of the outlet port 4. As the cross-sectional area of the outlet port 4 remains unrestricted even when the discharge flow through the outlet port is reduced, any tendency of clogging of the outlet port 4 is eliminated. Even when the discharge flow through the outlet port 4 is reduced to its minimum value one can always depend on secondary" fluid turbulences existing adjacent the outlet port 4, which turbulences will keep the outlet port 4 clean from any clogging material. This is of course made easier by the fact that the outlet port 4 can have a substantial cross-sectional area. However, it is appreciated that it is also possible to rotate the body 7 so far that it partially covers the outlet port 4 and thus restricts the flow area thereof. Such a position of the body 7 may be found suitable for reducing the amount of fluid being discharged, when the vortex-type separator is operated with a small pressure drop and thus a comparatively slow fluid vortex is produced in the vortex chamber. Such an operation with a small pressure drop is primarily of interest when separating heavy substances, as for instance sand, which on the other hand have a substantially smaller tendency of clogging the outlet port 4, wherefore a restriction of the flow area of the outlet port will not cause any serious problems.

In the embodiment of the invention schematically illustrated in FIGS. 4 and 5 the outlet port 4 from the vortex chamber 1 is located in the bottom 14 of the vortex chamber immediately close to the circumferential cylindrical wall of the chamber. The fluid vortex in the chamber 1, having the direction indicated by the arrow 6, can in this embodiment of the invention be more or less deflected from the outlet port 4 by the aid of a body 13. This body 13 extends along the circumferential wall of the vortex chamber 1 for about threefourths of the complete circumference and has a uniform radial breadth over its entire length. The axial height of the body 13, however, increases continuously from the bottom of the vortex chamber 1 so that the upper surface l5 of the body 13 forms a helix extending along the circumferential wall of the vortex chamber 1 and climbing gradually above the bottom I4 of the vortex chamber in the flow direction 6 of the fluid vortex. ln the illustrated embodiment of the invention, the body 13 is attached to a thin disc 16 which is rotatable in the bottom 14 of the vortex chamber by means of a pivot pin 17 so that the body 13 can be rotated about the axis of the vortex chamber. It is appreciated that the helical upper surface 15 and the cylindrical inner surface 18 of the body 13 will deflect the fluid vortex from the bottom and the cylindrical circumferential wall of the vortex chamber 1 at the location of the outlet port 4. The closer to the outlet port 4 the higher end of the body 13 is located the more pronounced this deflection will be and thus the smaller the amount of fluid being discharged through the outlet port 4. lt is also appreciated that the outlet port 4 could just as well be located in the circumferential wall of the vortex chamber in the same way as in the embodiment of the invention illustrated in FIGS. 1 to 3. Also, the body 13 can be rotated so as to cover the outlet port 4 partially and restrict the effective flow area thereof.

The embodiment of the invention illustrated in FIGS. 6 and 7 is distinguished from the embodiment illustrated in FIGS. 4 and 5 primarily in that the body 19 for deflecting the fluid vortex 6 from the outlet port 4 of the vortex chamber is shaped in a different way. ln this embodiment of the invention this flowdeflecting body 19 has a uniform axial height substantially corresponding to the axial height of the vortex chamber 1 but instead a radial breadth which increases continuously as seen in the flow direction 6 of the fluid vortex. The body 19 is attached to a thin disc or plate 20 forming the bottom in the vortex chamber 1. This disc 20 is rotatable in the vortex chamber body by means of a pivot pin 21, so that the body 19 can be rotated relative to the vortex chamber 1 about its axis. It is appreciated that the spiral-curved inner surface 22 of the body 19 will deflect the fluid vortex in the vortex chamber 1 from the circumferential cylindrical wall of the chamber at the location of the outlet port 4 and that this deflection will become the more pronounced the closer to the outlet port 4 the broader end of the body 19 is located. Of course, the body 19 can also be rotated so far that it covers the outlet port 4 partially.

In the embodiment of the invention illustrated in FIG. 8 the fluid vortex 6 in the vortex chamber 1 is deflected from the outlet port 4 by means of a plate spring 23 mounted in the vortex chamber 1. This plate spring has a breadth in the axial direction of the vortex chamber substantially corresponding to the axial height of the chamber and has its one end 23 attached to the circumferential wall of the chamber so as to extend from this end in the flow direction 6 of the fluid vortex to a point close to the outlet port 4-. The end 23 of the plate spring 23 closest to the outlet port 4 can be positioned at a variable radial distance from the circumferential wall of the vortex chamber by means of a screw 24 or a similar member threaded through the circumferential wall of the vortex chamber. It is appreciated that the deflection of the fluid vortex from the outlet port 4 will become more pronounced so that the amount of fluid being discharged through the outlet opening is reduced, when the free end 23" of the plate spring 23 is moved to a position closer to the center of the vortex chamber.

lclaim:

1. A device for discharging a heavy bottom fraction from a vortex type separator, comprising a substantially cylindrical vortex chamber connected to the separator to receive said heavy bottom fraction therefrom in a manner producing a fluid vortex in the vortex chamber, said vortex chamber having a cylindrical circumferential wall and being provided with a stationary outlet port located at the cylindrical circumferential wall of the vortex chamber, a flow-guiding member disposed in an adjustable position within said vortex chamber, said flow-guiding member having a flow-deflecting surface with an upstream end and a downstream end relative to the vortex flow and extending between said upstream end and said downstream end obliquely relative to the predominating flow direction of the vortex flow, the downstream end of the flowdeflecting surface being located in the vicinity of and upstream of said outlet port such that the flow-deflecting surface will deflect at its upstream end the vortex away from the cylindrical circumferential wall of the vortex chamber at the location of said outlet port, and means for varying the position of said flow-guiding member and thereby the distance between the outlet port and the downstream end of the flow deflecting surface.

2. A device as claimed in claim 1, wherein said adjustable flow-deflecting member includes a body forming the bottom of said vortex chamber, said body being rotatable about the axis of symmetry of the'vortex chamber and having an upper side facing the vortex chamber including said flow-deflecting surface having a first, substantially semicircular surface perpendicular to the axis of the vortex chamber, a second substantially semicircular surface inclined relative to the axis of the vortex chamber and a triangular surface joining said first tinuously from the bottom of the vortex chamber in the direction of the vortex flow, said body being rotatable relative to the vortex chamber about the axis of'the chamber.

'4. A device as claimed in claim 1, wherein said adjustable flow-deflecting member includes a body extending close to the circumferential wall of the vortex chamber for a portion only of the complete circumference and having a substantially constant axial height substantially corresponding to the axial height of the vortex chamber and a radial breadth which increases continuously in the direction of the vortex flow, said body being rotatable relative to the vortex chamber about the axis of the chamber.

5. A device as claimed in claim 1, wherein said adjustable flow-deflecting member includes a plate spring having a breadth substantially corresponding to the axial height of the vortex chamber and a length corresponding to a portion only of the circumferential length of the vortex chamber, said plate spring having one end attached to the circumferential wall of the vortex chamber and extending from said one end in the direction of the vortex flow so as to have an opposite end located upstream of the outlet port of the vortex chamber,

said means for varying the position of the flow-deflecting member comprising means for varying the position of said opposite end of said plate spring in a radial direction relative to the circumferential wall of the vortex chamber.

Claims

1. A device for discharging a heavy bottom fraction from a vortex type separator, comprising a substantially cylindrical vortex chamber connected to the separator to receive said heavy bottom fraction therefrom in a manner producing a fluid vortex in the vortex chamber, said vortex chamber having a cylindrical circumferential wall and being provided with a stationary outlet port located at the cylindrical circumferential wall of the vortex chamber, a flow-guiding member disposed in an adjustable position within said vortex chamber, said flow-guiding member having a flow-deflecting surface with an upstream end and a downstream end relative to the vortex flow and extending between said upstream end and said downstream end obliquely relative to the predominating flow direction of the vortex flow, the downstream end of the flow-deflecting surface being located in the vicinity of and upstream of said outlet port such that the flow-deflecting surface will deflect at its upstream end the vortex away from the cylindrical circumferential wall of the vortex chamber at the location of said outlet port, and means for varying the position of said flow-guiding member and thereby the distance between the outlet port and the downstream end of the flow deflecting surface.

2. A device as claimed in claim 1, wherein said adjustable flow-deflecting member includes a body forming the bottom of said vortex chamber, said body being rotatable about the axis of symmetry of the vortex chamber and having an upper side facing the vortex chamber including said flow-deflecting surface having a first, substantially semicircular surface perpendicular to the axis of the vortex chamber, a second substantially semicircular surface inclined relative to the axis of the vortex chamber and a triangular surface joining said first and second semicircular surfaces, said triangular surface being parallel to the axis of the vortex chamber and extending substantially diametrically through the vortex chamber.

3. A device as claimed in claim 1, wherein said adjustable flow-deflecting member includes a body extending close to the circumferential wall of the vortex chamber for a portion only of the complete circumference and having a substantially constant radial breadth and an axial height which increases continuously from the bottom of the vortex chamber in the direction of the vortex flow, said body beiNg rotatable relative to the vortex chamber about the axis of the chamber.

4. A device as claimed in claim 1, wherein said adjustable flow-deflecting member includes a body extending close to the circumferential wall of the vortex chamber for a portion only of the complete circumference and having a substantially constant axial height substantially corresponding to the axial height of the vortex chamber and a radial breadth which increases continuously in the direction of the vortex flow, said body being rotatable relative to the vortex chamber about the axis of the chamber.

5. A device as claimed in claim 1, wherein said adjustable flow-deflecting member includes a plate spring having a breadth substantially corresponding to the axial height of the vortex chamber and a length corresponding to a portion only of the circumferential length of the vortex chamber, said plate spring having one end attached to the circumferential wall of the vortex chamber and extending from said one end in the direction of the vortex flow so as to have an opposite end located upstream of the outlet port of the vortex chamber, said means for varying the position of the flow-deflecting member comprising means for varying the position of said opposite end of said plate spring in a radial direction relative to the circumferential wall of the vortex chamber.