US3105044A

US3105044A - Separator

Info

Publication number: US3105044A
Application number: US14699A
Authority: US
Inventors: Edwin P Troland
Original assignee: Bird Machine Co Inc
Current assignee: Bird Machine Co Inc
Priority date: 1960-03-14
Filing date: 1960-03-14
Publication date: 1963-09-24
Anticipated expiration: 1980-09-24
Also published as: FI40067C; GB897057A; DE1417623B1; NO115070B; BE601335A; FI40067B; CH388267A

Description

Sept. 24, 1963 E. P. TROLAND SEPARATOR Filed March 14. 1960 United States Patent 3,105,044 SEPARATOR Edwin P. Troland, Hingham, Mass, assignor to Bird Machine Company, South Walpole, Mass, :1 corporation of Massachusetts Filed Mar. 14, 1960, Ser- No. 14,699 3 Claims. (til. 210-512) This invention relates to apparatus for separating solid particles and gas bubbles from a liquid suspension and pertains more specifically to a cyclone-type separator adapted to purify paper pulp.

Cyclone-type separators have been proposed for purifying paper pulp and have been found to be highly effective for the removal of dirt particles, shives, and the like from the aqueous pulp dispersion. When operated with the restricted outlet discharging rejected particles freely to the atmosphere, however, it is impossible to remove air or other gas bubbles from the pulp even though it would e expected that the bubbles would migrate to the central hollow vortex of the liquid which is produced in such devices during operation. It appears that any bubbles which do migrate to the hollow vortex are again intermingled with the liquid dispersion as the latter leaves the device through the main outlet for the purified dispersion. Indeed, additional air is frequently drawn in through the restricted outlet of such a device and intermingled with the liquid suspension so that the device not only fails to removebubbles but actually introduces additional bubbles. Although it has been proposed to employ a suction pump to remove gases from within the hollow vortex through a separate pipe or tube or to have the restricted outlet of the device discharge into an evacuated chamber in order to remove gas bubbles as well as dirt from the dispersion, such expedients add substantially to the cost of installation and operation of the device.

One object of the present invention is to provide a cyclone-type separator of simple and inexpensive construction adapted to purify paper pulp by removing from it both gas bubbles and dirt particles.

Another object is to provide a separator of the type described which can be operated with its restricted outlet discharging continuously at any pressure, even above atmospheric pressure, without the need for any suction pump or similar pressure-reducing means for removing the gas.

Other and further objects will be apparent from the drawing and from the description which follows.

In the drawing:

FIG. 1 is a view in side elevation, partly broken away and in section, showing one embodiment of the present invention;

FIG. 2 is a view in cross section taken along line 22 of FIG. 1;

FIG. 3 is a view in vertical section on an enlarged scale, partly broken away, showing another embodiment of the invention;

FIG. 4 is a view in cross section taken along line 4-4 of FIG. 3; and 7 FIG. is a view in vertical section, partly broken away, showing still a third embodiment of the invention.

()ne of the preferred embodiments of the present invention as illustrated in FIGS. 1 and 2 of the drawing includes an elongated chamber 1% of circular cross-sectional configuration tapering in diameter as shown at 12 adjacent one end where it terminates in a centrally located restricted orifice or outlet 14. At the other end of the chamber 10, an inlet 16 is provided arranged tangentially to the chamber, as best appears in FIG. 2 of the drawing. A second or main outlet 18 in the form of a tubular discharge member is disposed centrally of the chamber ad jacent the same end as that at which inlet 16 is located.

Outlet 18 is tubular in form, having a cylindrical wall which extends into the chamber and terminates in an open end 2% disposed beyond inlet 16 along the axis of the chamber in the direction of restricted outlet 14.

Mounted on a cross bar or spider 22 secured within outlet 13 is a projecting core'element 2,4 which is located centrally of tubular outlet 18 and which has a smooth end face 26 flush with the open end 20, forming together with the tubular member an annular outlet.

In operation of this embodiment, the paper pulp dispersion containing dirt particles and bubbles of air or other gas is introduced under pressure through inlet 16, the stream of pulp dispersion progressing in spiral fashion along the length of chamber 10 toward restricted outlet 14. As the rapidly rotating mass of liquid dispersion advances spirally through chamber 10, it is turned back upon itself at some point in the tapering portion 12 of the chamber and forms an inner annular layer of pulp dispersion progressing through chamber 10 toward the main outlet 13. Because of the high gravitational forces developed within the rapidly rotating mass of liquid, a hollow vortex or core 23 is formed, as indicated by dotted lines. This hollow vortex is normally continuous to the restricted outlet 14 and is continuously in communication with the ambient atmosphere through this outlet, although it may be operated successfully with outlet 14 discharging at either elevated or reduced pressure.

The precise diameter of hollow vortex 28 will depend upon the rotational speed of the liquid mass within the chamber (which in turn is dependent upon the overall dimensions of the device and the pressure drop through it, which is usually 40 to 60 p.s.i.), the pressure of the atmosphere with which the hollow vortex is in communication through restricted outlet 14, and the diameter of the periphery of tubular outlet or vortex finder 18. By proportioning the diameter of core element 24 so that it is somewhat greater than the diameter of hollow vortex 28, preferably about 10% to 26% greater, it is found that bubbles of air or other gas which migrate to the hollow vortex of the spinning mass of liquid pulp dispersion are obstructed and prevented from becoming redispersed in the liquid as it leaves the device through outlet 18. Instead, as the air or gas bubbles accumulate within hollow vortex 23, any excess gas is freely vented to the atmosphere through restricted outlet 14.

It is not essential that the end 26 of core element 24 be perfectly flat, but it is preferably smooth in order to minimize the possibility of producing turbulence which would result in the gas bubbles becoming entrapped or entrained again within the pulp dispersion as it proceeds through outlet 18.

The length of core element 24 and the position Within tubular outlet 18 of spider 22 are not critical. The position of spider 22, for example, may be varied from the region of the open end 20 of tubular outlet 18 to a position several inches removed from the open end. The spider must be sturdy enough to support core element 24 securely while at the same time being slender enough to avoid excessive obstruction of the flow of dispersion through outlet 18.

in another embodiment, as illustrated in FIGS. 3 and 4, the upper part of chamber 10 (the lower part'is identical with that of FIG. 1) is provided with an annular flange 30 to which is bolted a unitary cast head 32 which includes a centrally located main outlet 36 in the form of a tubular discharge member the peripheral wall of which converges toward an open end 38. Outlet 36 also converges outside of chamber 10 to a bolting flangeA-t which serves to secure the device to a main outlet pipe 42 for accepted stock.

Mounted within outlet 36 is a cross bar or spider 44 which serves to support a core element 46 disposed cen:

ale-5,044

3 trally of outlet 36 and extending along the axis of outlet 36 toward open end 38. Core element 46 is provided with a tapped opening in its terminal face adapted to receive a threaded projection on a supplemental core element 48. Supplemental core element 48 is not of uniform diameter as is core element as, but increases gradually in diameter beyond open end 38, terminating in a smooth, circular, gently rounded face 54 Terminal face 59 in this embodiment preferably is disposed beyond open end 38 along the axis of the chamber toward re stricted outlet 14 by a distance at least equal to the diameter of the open end.

Because of the projection of core element 48 Within chamber 10 beyond the open end 38 of the main outlet, it is possible to make the vortex-obstructing face 5% of considerably greater diameter than core element do without reducing the flow capacity of the annular passageway at open end 38. This additional diameter of terminal face 59 provides additional insurance against the possibility that hollow vortex 28, the position of which changes slightly and erratically under ordinary operating conditions, might extend beyond the margin of obstructing face 50 and permit some of the gas contained within it to be entrained in the liquid dispersion as it exits from chamber 1%) through open end 38 of the main outlet. In a preferred embodiment, core element as has a diameter from to 20% greater than that of the hollow vortex Within the liquid during operation of the device while obstructing face 50 has a diameter from to 109% greater than that of the hollow vortex. The diameter of the core and of face 59 cannot exceed about 50% of the adjacent inner diameter of chamber 16 without seriously impairing the eflioiency and effectiveness of the separating function of the apparatus. For the same reason, the obstructing face 54) as well as core element 48 cannot be supported from the Wall of chamber to by a spider or by brackets, which disturb the flow pattern of the liquid dispersion, but are supported from the interior of the main outlet, just as in the case of the embodiment shown in FIG. 1 of the drawing.

If the length of core element 48 is very great, so that terminal obstructing face 5% is spaced from open end 38 by a distance greater than about four times the diameter of the open end, it is found that the air or gas bubbles tend to migrate to the center before the entering stream of liquid dispersion feed passes beyond terminal face 56. Consequently, these bubbles strike the cylindrical side wall of core element 48 and are carried along it through open end 38 by the accepted pulp dispersion which is leaving the device. The preferred position for the obstructing face 5!) of the embodiment shown in FIG. 3 is accordingly in a zone extending from the open end of the main outlet along the axis of the chamber toward the restricted outlet at a distance from the open end ranging from one to. four diameters of the open end of the main outlet.

The supporting spider 44 is preferably spaced from open end 38 by a distance at least equal to the diameter of the open end in order to minimize obstruction of the annular outlet passage. The increasing diameter of tubular outlet 36 as the flow of accepted dispersion proceeds toward outlet .pipe 42 makes it possible to provide a very strong and rigid support for the core element Without reducing the effective capacity of the outlet.

In a third embodiment of the invention, as shown in FIG. 5, tubular discharge member or outlet 64} is flared outwardly adjacent its open end 62, and is provided with a core element 64- mounted on a supporting cross bar as and terminating in a smooth circular face 68 which is disposed within outlet 6%} spaced from its open end.

This embodiment is somewhat less effective than the embodiments of FIGS. 1 and 2 for removing dirt particles from the dispersion, but is somewhat more effective for removing gas bubbles than are the other two embodiments. It is found that the flaring wall of tubular outlet or vortex finder 69 tends to stabilize the hollow vortex 28, while the recessed position of the terminal obstructing face 68 ensures that all 'of the bubbles which migrate toward the center of the rotating mass of liquid have time to reach the vortex before being carried past face 63 by the departing stream of pulp dispersion as it proceeds through tubular outlet 69. Having once reached the hollow vortex, the bubbles are prevented from passing through with the accepted material by the obstructing face 63.

Although specific embodiments of the invention have been described herein, it is not intended to limit the invention solely thereto, but to include all of the obvious variations and modifications within the spirit and scope of the appended claims.

What is claimed is:

1. Apparatus for separating solid particles and gas bubbles from a liquid suspension comprising a chamber having a substantially circular cross-section and a conical end portion, an inlet arranged tangentidly with respect to said chamber adjacent one end thereof remote from the apex of said conical portion for introducing said suspension into said apparatus to form a stream which initially passes spirally along the wall of said chamber toward the apex of the conical portion thereof and which reverses inwardly on itself before reaching said apex to form a hollow vortex, a firs-t outlet for rejected solids and gas at the apex of said conical portion in communication with said hollow vortex, a second outlet for accepting suspension having its mouth disposed centrally of said chamber between said inlet and said apex in position to receive the reverse flow of liquid suspension from around sm'd hollow vortex, and an element mounted within said chamber having an obstructing face centrally aligned with respect to said month, said face being disposed between said inlet and said apex substantially in the plane of the mouth of the second outlet and having a diameter at least as great as tne diameter of said vortex and less than the diameter of said mouth to block the passage of said vortex through said second outlet while permitting the liquid suspension to pass around the periphery of said face.

2. Apparatus for separating solid particles and gas bubbles from a liquid suspension comprising a chamber having a substantially circular cross-section and a conical end portion, an inlet arranged tangentially with respect to said chamber adjacent one end thereof remote from the apex of said conical portion for introducing said suspension into said apparatus to form a stream which initially passes spirally along the wall of said chamber toward the apex of the conical portion thereof and which reverses inwardly on itself before reaching said apex to form a hollow vortex, a first outlet for rejected solids and gas at the apex of said conical portion in communication with said hollow vortex, a second outlet for accepting suspension having its mouth disposed centrally of said chamber between said inlet and said apex in position to receive the reverse flow of liquid suspension from around said hollow vortex, said second outlet converging in the direction of outlet flow from said mouth, and an element mounted within said second outlet having an obstructing face centrally aligned with respect to said mouth, said face being disposed between said inlet and said apex within said second outlet in the plane of the minimum diameter thereof and having a diameter at least as great as the diameter of said vontex and less than said minimum diameter to block the passage of said vortex through said second outlet while permitting the liquid suspension to pass around the periphery of said face.

3. Apparatus for separating solid particles and gas bubbles from a liquid suspension comprising a chamber having a substantially circular cross-section and a conical end portion, an inlet arranged tangentially with respect to said chamber adjacent one end thereof remote from the apex of said conical portion for introducing said suspension into said apparatus to form a stream which initially passes spirflly along the wall of said chamber toward the apex of the conical portion thereof and which reverses inwardly on itself before reaching said apex to form a hollow vortex, a first outlet for rejected solids and gas at the apex of said conical portion in communication with said hollow vontex, a second outlet for accepting suspension having its mouth disposed centrally of said chamber between said inlet and said apex in position to receive the reverse flow of liquid suspension from around said hollow vortex, and an obstruction element mounted within said second outlet and centrally aligned with respect to said mouth, said element extending from within said mouth to a point therebeyond to provide a vortex obstructing portion having a diameter at least as great as the diameter of said vortex and not more than 50 percent of the adjacent inner diameter of said chamber disposed between said mouth and a distance from said mouth of at most about four times the mouth diameter, said portion being effective to block passage of said vortex through said second outlet While permitting the liquid to pass around the periphery thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,566,662 Hill Sept. 4, 1951 2,757,581 Freeman et al. Aug. 7, 1956 2,816,490 Broadway et a1. Dec. 17, 1957 2,835,387 Fontein May 20, 1958 2,878,934 Tomlinson Mar. 24, 1959 FOREIGN PATENTS 740,588 Great Britain Nov. 16, 1955 523,316 Canada Mar. 27, 1956

Claims

1. APPARATUS FOR SEPARATING SOLID PARTICLES AND GAS BUBBLES FROM A LIQUID SUSPENSION COMPRISING A CHAMBER HAVING A SUBSTANTIALLY CIRCULAR CROSS-SECTION AND A VONICAL END PORTION, AN INLET ARRANGED TANGENTIALLY WITH RESPECT TO SAID CHAMBER ADJACENT ON END THEREOF REMOTE FROM THE APEX OF SAID CONICAL PORTION FOR INTRODUCING SAID SUSPENSION INTO SAID APPARATUS TO FORM A STREAM WHICH INITIALLY PASSES SPIRALLY ALONG THE WALL OF SAID CHAMBER TOWARD THE APEX OF THE CONICAL PORTION THEREOF AND WHICH REVERSES INWARDLY ON ITSELF BEFORE REACHING SAID APEX TO FORM A HOLLOW VORTEX, A FIRST OUTLET FOR REJECTED SOLIDS AND GAS AT THE APEX OF SAID CONICAL PORTION IN COMMUNICATION WITH SAID HOLLOW VORTEX, A SECOND OUTLET FOR ACCEPTING SUSPENSION HAVING ITS MOUTH DISPOSED CENTRALLY OF SAID CHAMBER BETWEEN SAID INLET AND SAID APEX IN POSITION TO RECEIVE THE REVERSE FLOW OF LIQUID SUSPENSION FROM AROUND SAID HOLLOW VORTEX, AND AN ELEMENT MOUNTED WITHIN SAID CHAMBER HAVING AN OBSTRUCTING FACE CENTRALLY ALIGNED WITH RESPECT TO SAID MOUTH, SAID FACE BEING DISPOSED BETWEEN SAID INLET AND SAID APEX SUBSTANTIALLY IN THE PLANE OF THE MOUTH OF THE SECOND OUTLET AND HAVING A DIAMETER AT LEAST AS GREAT AS THE DIAMETER OF SAID VORTEX AND LESS THAN THE DIAMETER OF SAID MOUTH TO BLOCK THE PASSAGE OF SAID VORTEX THROUGH SAID SECOND OUTLET WHILE PERMITTING THE LIQUID SUSPENSION TO PASS AROUND THE PERIPHERY OF SAID FACE.