Self-sealing valve assembly to facilitate unplugging of a centrifugal cleaner

A self-sealing element is provided in the outer wall of the discharge chamber of a centrifugal cleaning apparatus opposite the rejects discharge outlet. When a blockage occurs at the discharge outlet, a long needle-like nozzle is inserted through the sealing element to the blockage. Water or air under pressure is expelled from orifices in the nozzle and breaks up the blockage. After the nozzle is withdrawn, the sealing element, which may be formed of a silicone rubber, reseals itself.

BACKGROUND OF THE INVENTION 
The present invention relates to apparatus for separating undesired 
particles from liquids and liquid suspensions, and, more particularly, to 
apparatus for the centrifugal separation of undesired particles from paper 
pulp stock. 
Vortex chambers for separating solid particles from a liquid suspension are 
well-known. These chambers, commonly called hydrocyclones or liquid 
cyclones, are usually elongated, of circular cross-section, and may be 
either somewhat tapered or cylindrical as required. The suspension to be 
treated is introduced under pressure through a restricted tangential 
inlet, imparting a high velocity spiral flow to the suspension. A vortex 
is developed and extends from the inlet end of the chamber to its opposite 
end. Velocities are high enough that an axial gas core is formed at the 
center of the chamber. Larger and heavier particles are thrown outwardly 
against the sides of the chamber and migrate toward a rejects outlet at 
the end of the chamber opposite the inlet. Accepted stock is removed at 
the end opposite the rejects outlet. 
Cyclones are commonly used to separate sand, grit, bark particles, and 
shives from cellulose fibers in a papermaking slurry. As the trend in the 
paper-making industry has been to utilize more of the tree, including 
branches and twigs, more bark ends up in the cooking and pulping process. 
This necessitates the use of cyclone cleaners to remove bark and other 
impurities. Since cyclones become more efficient at removing smaller 
particles as the diameter of the cyclone is decreased, the industry has 
moved to utilize larger numbers of smaller cyclones, such as cyclones 
having an inner diameter of 6 inches or less. 
However, use of smaller sized cyclones causes problems at the rejects end 
of the apparatus where the discharge outlet may be only 1/2 inch or less 
in diameter. Consequently, there is the great possibility of the narrowing 
or clogging of the outlet with bark particles, shives, and other 
impurities. Narrowing or clogging of the discharge outlet has an immediate 
adverse effect on the separating ability of the cyclone and must be 
remedied. 
Early cyclones had to be partially disassembled to remove the particles 
plugging the outlet. Naturally, this remedial procedure was time consuming 
and costly. Later cyclone designs utilized a common manifold connected to 
the outlet ends of a series of cyclones which had a single, larger 
diameter orifice located therein, such as the reject control system taught 
by Rastatter, U.S. Pat. No. 3,543,932. Other cyclone designs, such as the 
one taught by Jakobsson et al, U.S. Pat. No. 3,696,927, utilized a 
variable sized rejects outlet opening. 
Still other cyclone arrangements made provisions for directing water or 
compressed air into the rejects outlet to remove blockages. The clustered 
cyclone apparatus taught by Rastatter, U.S. Pat. No. 3,940,331, made 
provisions for a series of valves in an outer wall of the apparatus 
opposite the rejects outlets of the cyclones which could be opened in the 
event of a blockage. 
However, the prior art cyclone devices contained additional elements which 
made the cyclone structure more complex and which themselves could be 
subject to operational problems. Accordingly, the need still exists in the 
art for a simple, inexpensive, and quick mode of removing blockages from 
the rejects outlet of a cyclone cleaning apparatus. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, an elastomeric sealing element is 
provided in the outer wall of the discharge housing of a cyclone cleaning 
apparatus. The sealing element may be of an elastomeric material such as a 
silicone rubber which is capable of sealing itself after being pierced. 
The sealing element is aligned generally opposite the discharge outlet of 
the cyclone. It may be held in position by a hollow screw pressing the 
element into a recess in the wall, or may be a grommet-like element having 
an enlarged head and/or tail portion which spans an aperture in the wall. 
In operation, the outer wall of the discharge housing is preferably 
fabricated of a transparent material such as a polymeric resin to permit 
viewing of the discharge outlet of the cyclone. The cyclone cleaning 
apparatus may consist of only a single cyclone or may contain a plurality 
of cyclones, the discharge housing being sized accordingly. When it 
appears that the discharge outlet of the cyclone has become blocked, as 
evidenced by a lack of flow therethrough, the blockage is removed by 
inserting a sharply-tipped elongated nozzle, attached to a supply of 
pressurized fluid such as water or air, through the sealing element in the 
outer wall of the housing and into the discharge outlet. Pressurized fluid 
is then jetted against the sides of the rejects discharge end of the 
cyclone to break up and remove accumulated particles of sand, grit, bark, 
shives, or other material. Once the blockage is removed, the flow of fluid 
to the nozzle is turned off and the nozzle withdrawn from the discharge 
housing. The sealing element reseals itself as the nozzle is withdrawn. 
Accordingly, it is an object of this invention to provide quick and easy 
access to the discharge outlet of a cyclone cleaner apparatus; it is a 
further object of this invention to provide a self-sealing element which 
can be pierced by a sharply-tipped elongated nozzle. These and other 
objects and advantages of the invention will become apparent from the 
following description, the accompanying drawings, and the appended claims,

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As illustrated in FIG. 1, the cyclone cleaning apparatus includes a hollow 
cyclone member 10 having a cylindrical portion 12, a frustoconical portion 
14, and an apex cone portion 16 which has an outlet port 17. The apparatus 
may be arranged in a cluster of cyclones as shown and as taught by 
Rastatter, U.S. Pat. No. 3,940,331. The cylindrical and frustoconical 
portions of the cyclone body may be formed of a polymeric resin material 
such as polypropylene, polystyrene, nylon, or the like. The apex cone 
portion 16 of cyclone member 10 is preferably formed of a ceramic material 
which resists abrasion. It may be formed by casting in a known manner. 
The cylindrical portion 12 of the cyclone has a tangentially extending 
slot-like inlet 18 through which a fluid suspension of material, such as 
paper stock, will enter the apparatus. Adjacent the end of cylindrical 
portion 12 of the cyclone body, a closure cover 20 is provided which may 
be fabricated of the same polymeric resin material as other portions of 
cyclone member 10. Closure cover 20 and the end of cylindrical portion 12 
may be threaded to provide for sealing engagement. Closure cover 20 is 
also provided with a centrally located vortex finder or overflow nozzle 
tube 22 which opens into chamber 24 and extends inwardly into the center 
of cylindrical portion 12. 
Chamber 24 is designed to receive the portion of the fluid suspension 
having the separated lighter fraction, commonly termed the "accepts". 
Chamber 24 may be connected to a vacuum source (not shown) which serves to 
deaerate the stock as it is sprayed from tube 22 into chamber 24. This 
deaerated stock can then be sent to a receiving apparatus such as the head 
box of a papermaking machine. 
Cyclone member 10 includes an apex cone portion 16 which is preferably 
formed of an abrasion resistant cast ceramic material. The cone portion 16 
forms an extension of frustoconical portion 14, and can be formed with an 
outwardly projecting threaded portion 26 as an original part thereof for 
receiving an annular internally threaded coupling nut 28. Alternatively, 
the threaded portion may be cemented in place on the cone portion 16 in a 
known manner. Coupling nut 28 serves to seal cone portion 16 to 
frustoconical portion 14. 
The apex cone portion 16 of the cyclone member having outlet port 17 
projects into a generally circular opening 30 formed within the flat inner 
wall 32 of a generally cylindrically shaped housing 34 which defines a 
discharge chamber 36. The housing 34 includes an outer wall 38 which is in 
spaced relationship with inner wall 32. As shown in FIG. 1, an annular 
shoulder 40 is formed on the apex cone portion 16 and abuts inner wall 32 
of housing 34. A nut 42 engages threads which can be formed as an integral 
part of apex cone portion 16 and provides for securing the apex cone 
portion to the inner wall 32 of the discharge housing 34. Alternatively, 
the threads may be formed on an annular sleeve made of a plastic material 
such as nylon and cemented to the apex cone portion 16. 
As can be seen in FIG. 1, the apex cone portion 16 of cyclone member 10 
terminates in discharge chamber 36 generally opposite threaded opening 44 
in outer wall 38. A valve assembly 46 mounted in opening 44 has ribbed 
portions 48, threaded wall portion 50, and transverse wall portion 52. The 
ribbed portions 48 enable a tool to engage the valve assembly when 
inserting it into place or when removing it if replacement is required. 
The threads on wall portion 50 match those on opening 44 to provide a 
tight seal when the valve assembly is in place. 
As best shown in FIG. 2, valve assembly 46 has a transverse wall 52 which 
extends across the threaded wall portion 50 of the valve and has a small, 
generally cylindrical passage 54 therethrough. Passage 54 is in general 
alignment with outlet port 17 of apex cone portion 16 of cyclone member 
10. Valve assembly 46 may be fabricated at least in part from a 
transparent polymeric resin material to enable viewing of the flow of 
material from the outlet of the apex cone portion 16 of the cyclone. It is 
to be understood that it is not essential to use a removable valve 
assembly 46, in that the transverse wall portion 52 can be simply a 
portion of the housing wall 38 which is counterbored and threaded to 
receive the screw 58. 
Sealing element 56 spans passage 54 and is seated in a counterbored portion 
of transverse wall portion 52. It is held in position in FIG. 2 by a 
hollow headed screw element 58. Sealing element 56 may be of any resilient 
elastomeric material which is capable of resealing itself after being 
pierced by a sharp implement. By resealing it is meant that the 
elastomeric material will press against the hole made by the implement and 
seal it against any leakage of fluid through the element. An example of a 
material suitable for use is silicone rubber. Room-temperature vulcanizing 
(RTV) silicone rubber is available in various grades from the General 
Electric Company, Waterford, N.Y., and under the trademark Silastic from 
the Dow Corning Corporation, Midland, Mich. As best illustrated in FIG. 2, 
sealing element 56 may be a unitary disc-shaped element having tapered 
edges 60 adapted to fit snugly into countersunk recesses 62 in transverse 
wall portion 52 to seal passage 54. 
Other embodiments of the sealing element are illustrated in FIGS. 3a-3d. 
The embodiments of FIGS. 3a-3c do not require a screw to maintain them in 
place. In FIG. 3a, the sealing element 56a is generally cylindrically 
shaped and has enlarged cylindrically shaped head and tail portions 57a. 
They extend over the edges of transverse wall portion 52a to lock the 
element in place in passage 54a. Element 56a may be formed in place in 
passage 54a or may be fitted into the passage by compressing head or tail 
portion 57a and sliding the element into passage 54a. 
The sealing element illustrated in FIG. 3b also comprises a generally 
cylindrically shaped element 56b having enlarged head and tail portions 
57b. However, in this embodiment, the edges of transverse wall portion 52b 
have counterbored areas into which head and tail portions 57b fit. The 
sealing element can be molded in place in the passage 54b. 
In the embodiment illustrated in FIG. 3c, the exterior side of transverse 
wall portion 52c is counterbored, and the head portion of element 56c is 
enlarged to fit into that area. The tail portion of element 56c is 
compressed within passage 54c, but expands outwardly beyond the end of the 
passage to lock the element into place. 
The embodiment illustrated in FIG. 3d is a modification of the arrangement 
illustrated in FIG. 2. In this embodiment, unitary, cylindrically shaped, 
sealing element 56d is positioned in a counterbored recess in transverse 
wall 52d and held in place by hollow screw element 58d. 
In operation, and as best illustrated in FIGS. 4 and 5, a blockage 64 in 
the outlet port 17 of apex cone portion 16 of the cyclone can be observed 
as an absence of fluid flow into discharge chamber 36. The blockage can be 
removed by inserting a sharply-tipped probe or nozzle assembly 66 into 
valve assembly 46 and through sealing element 56. The nozzle assembly has 
a long, needle-like nozzle 68 with a handle 70. It is connected by hose 72 
to a source of water or air under pressure. 
When the nozzle 68 is in position in the apex cone portion 16, valve 74 is 
opened and water or air under pressure is expelled from orifices 76 in the 
tip of the nozzle to break up and remove the blockage. Preferably, at 
least some of the orifices are located to direct fluid directly against 
the wall of the apex cone portion 16. Alternatively, in some instances 
merely inserting the nozzle into the apex cone portion will be sufficient 
to remove a blockage without the need for use of any fluid under pressure. 
For such instances, a solid probe will be substantially as effective as a 
hollow nozzle. 
After the blockage has been removed, the nozzle is withdrawn from the 
cyclone and discharge chamber, and the elastomeric sealing element 56 will 
reseal itself. This procedure can be repeated whenever a blockage occurs. 
This construction of the sealing element greatly simplifies the cleaning 
operation and eliminates the need for manually opening and closing valves 
or partially disassembling a cyclone cleaning apparatus whenever a 
blockage occurs. 
While the apparatus described herein constitute preferred embodiments of 
the invention, it is to be understood that the invention is not limited to 
these precise apparatus, and that changes may be made therein without 
departing from the scope of the invention, which is defined in the 
appended claims.