Abstract:
An improved hydrocyclone and method of operating for centrifugal cleaning of pulp for papermaking wherein the hydrocyclone has a plurality of inserts each with openings of different sizes for selectively and interchangeably inserting into a stock entry opening and into a vortex finding outlet opening to adjust capacity and cleaning efficiency. In one form the inserts each can be changed by tubes of different openings which are installed into the inserts changing the opening sizes. In another form, the inserts are threadedly engaged with bosses or are adhered or frictionally fit into the bosses.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to improvements in the papermaking field, and more particularly to an improved method and apparatus for cleaning of papermaking pulp utilizing a hydrocyclone. 
     An important field of use for centrifugal separators is in the purifying of paper stock wherein wood pulp fibers are suspended in a water solution. In the operation of a centrifugal separator or hydrocyclone, the solution of pulp is directed into the hydrocyclone and the particles are separated in categories based on physical properties. The pulp solution is directed tangentially into the hydrocyclone chamber where, under the influence of centrifugal force, the particles are separated so that reject particles of a specific weight greater than the pulp, such as bark, shives, nodules, sand, ink specks, and the like are thrown outwardly and will pass downwardly through a reject opening at the base of the hydrocyclone chamber. The acceptable fraction which is the wood pulp fiber will pass outwardly through an opening at the top center of the hydrocyclone chamber. In other hydrocyclone type cleaners, lightweight particles, that is particles having specific weights less than the pulp, can be separated using the same principles. 
     Typically in commercial installations for the high efficiency removal of debris in paper stock, a plurality of hydrocyclone cleaners are connected in cleaner banks to process a substantial volume of paper stock. The hydrocyclone centrifugal cleaners may be used in a batch dump operation or a continuous operation. In each operation, the cleaner must be efficient and highly effective in removing the particles of contaminants, either heavyweight or lightweight. 
     Typically, with an installed cleaning system, there is limited capability to adjust either capacity or cleaning efficiency without changing the type or number of installed cleaners. Generally, the only means presently available is to adjust the consistency of the stock supplied either up or down and/or to adjust the operating pressures of the system. Raising the operating consistency yields a higher tonnage through the system but will lower the cleaning efficiency. Conversely, lowering the stock consistency can increase the cleaning efficiency but will lower the system output unless additional cleaners are added to the system. Running the cleaners at a higher pressure drop will raise the capacity, but the effect on cleaning efficiency can be positive or negative, depending on the specifics of the hydrocyclone and the contaminant involved. 
     Hydrocyclone geometry affects both the capacity and efficiency of the hydrocyclone. The limiting factors are the basic cleaner diameter and the ratio of the inlet orifice size and the overflow or vortex finder size to the cleaner&#39;s diameter. Therefore, system changes can be made without altering stock consistency or system pressures; however, previously geometric charges to the cleaners required substantial systems downtime and expense. 
     A feature of the present invention is to provide an improved apparatus and method for the cleaning of pulp utilizing a hydrocyclone for the removal of undesirable particles. 
     A further feature of the invention is to provide an improved cleaning system using hydrocyclones for the cleaning of papermaking pulp wherein the performance of the cleaner can be readily affected by adjusting the inlet orifice and vortex finder diameters. 
     A still further feature of the invention is to provide a hydrocyclone cleaning system which is field adjustable to obtain a more versatile system to accommodate changing mill requirements and wherein there is a capability to adjust either capacity or cleaning efficiency without changing the number or type of installed hydrocyclone cleaners. 
     SUMMARY OF THE INVENTION 
     The present invention provides a hydrocyclone cleaning system wherein one or more hydrocyclones are provided having a cyclone chamber therein of uniform acceptable size for a plurality of cleaning needs. The hydrocyclone has a tangential pulp inlet and an accept outlet at the top. Uniquely constructed interchangeable inlet nozzles and vortex finder tubes of varying diameters are provided, and interchange is made between inlets and vortex finders in an existing system to obtain a change in capacity or cleaning efficiency. The inlets and vortex finders have constructions so that they accommodate easy change in the field and can be replaced readily when needed, without disabling or disassembling the entire system. 
     Other objects, advantages and features will become more apparent with the teaching of the principles of the present invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims and drawings, in which: 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a vertical sectional view, shown in somewhat schematic form of a hydrocyclone embodying the principles of the present invention; 
     FIG. 2 is a fragmentary vertical sectional view of an insert for the stock entry opening of the cyclone of FIG. 1; 
     FIG. 3 is an end elevational view of the insert of FIG. 2; 
     FIG. 4 is a detailed vertical sectional view of the insert for the vortex finder opening of the cyclone of FIG. 1; 
     FIG. 5 is a top plan view of the insert of FIG. 4; 
     FIG. 6 is a vertical sectional view, shown in somewhat schematic form of a modified form of cyclone embodying the principles of the present invention; 
     FIG. 7 is a detailed sectional view taken through an insert for the stock entry opening of the cyclone of FIG. 6; 
     FIG. 8 is an end elevational view of the insert of FIG. 7; 
     FIG. 9 is a vertical sectional view taken through an insert for the vortex finder opening of the cyclone of FIG. 6; 
     FIG. 10 is a top plan view of the insert of FIG. 9; 
     FIG. 11 is a sectional view taken through the axis of a modified form of insert for the vortex finder opening of the cyclone of FIG. 6; 
     FIG. 12 is an end view of a portion of the structure of FIG. 11; 
     FIG. 13 is a vertical sectional view taken through a plastic insert for the structure of FIG. 11; and 
     FIG. 14 is an end view of the structure of FIG. 13. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a hydrocyclone 10 of the type which may be used singly or in groups for the cleaning of papermaking pulp. While the features of the invention find primary utilization in the cleaning of paper pulp, it will be understood that the features may be employed in other types of hydrocyclone cleaners such as may be used in the separation of solids in water supply systems, for removal in waste treatment plants, for bark separation in hydraulic barker systems and other commercial utilizations. 
     The hydrocyclone 10 of FIG. 1 has an upper portion 11 bolted to a lower portion 12 to form a hydrocyclone centrifugal cleaning chamber 13 therein. The upper section has an annular flange 14 matching a flange 15 of the lower section so that the two sections can be secured together by bolts as illustrated. It will be recognized by those skilled in the art, that the physical orientation of centrifugal cleaners is not necessarily critical to their operation. The forces occurring during operation dominate the cleaners performance such that cleaners will operate on their side or even inverted from the position shown in FIG. 1. The terms top, bottom, upper, lower and the like which imply physical orientation will be used herein only for clarity in explanation relative to the drawings and should not be considered limiting in term of the use or operation of the cleaners. 
     At the lower end of the chamber 13 is a reject opening 18 where the reject materials are discharged. In the case of pulp cleaning, such rejects will normally include the usual contaminants including particles of bark, shives, chop, fine sand and other materials which remain in the pulp with the preceding processing. 
     Pulp slurry is directed tangentially into the chamber 13 through an inlet insert 19a. The inlet is in the form of a sleeve which is frictionally inserted into an annular hollow boss 17 on the housing. The insert 19a has an opening 21 of a diameter A. While the inlet opening 21 has a cylindrical shape, in some instances other shapes such as oval or rectangular may be employed. The insert has an annular flange 20 to limit its insertion into the boss 17. 
     In accordance with the principles of the present invention, a plurality of inserts are provided with an alternate insert 19b shown in FIGS. 2 and 3. This insert has an external diameter so that it can be inserted into the boss 17 after the insert 19a is withdrawn, and has an internal bore or opening 22 of a diameter B which is of different size than the diameter A, and is shown in the drawings as being smaller. A flange 20 of the insert 19b limits its insertion into the boss. The operator can selectively choose the insert 19a or 19b to change the effective size of the stock entry opening which leads tangentially into the chamber 13. 
     The plurality of inserts can also be used to provide a plurality of inlet configurations. Thus, by changing inserts the inlet design can be changed from cylindrical to conical, or even rectangular. 
     The upper end of the chamber 13 is provided with an annular boss 16 adapted to receive an insert 23a. The insert 23a has a flange 25 at its upper end to fit snugly into the boss 16 and has a central overflow or vortex finder opening 24 of a diameter C. 
     A plurality of vortex finder inserts are provided with another being illustrated in FIGS. 4 and 5 at 23b. These are provided with flanges 25 and have a flow opening 24 therethrough of a diameter D which is shown to be smaller than the diameter C of the insert 23a. The operator can remove the inset 23a and substitute therefor the inset 23b to obtain a smaller vortex finder opening. It will be seen that by providing a plurality of inserts such as 23a and 23b for the vortex finder opening, different sizes of opening from the chamber 13 can be achieved. Also by having a plurality of inserts such as 19a and 19b, the operator can selectively choose the inlet flow opening. By changing these openings selectively, the operator has the capability to adjust either the capacity of cleaning efficiency without changing the type or number of hydrocyclone cleaners. The limiting factors of operating are the basic cleaner size and the ratio of the inlet orifice size and the overflow or vortex finder size to the cleaner&#39;s diameter and these can be selectively changed for optimum performance within the parameters of the circumstance of cleaning at which the mill is operating. 
     The inlet inserts 19a and 19b and the vortex finder inserts 23a and 23b can be frictionally fit into the respective bosses 17 and 16. Alternatively, adhesive can be used to secure the inserts in the bosses. 
     In FIG. 6 a modified form of cleaner 26 is shown having a hydrocyclone chamber 27 therein. In the arrangement of FIG. 6, the interchangeable inserts for the stock entry opening and for the overflow opening are threaded into place, rather than press fit into place as in the arrangement shown in FIG. 1. 
     In FIG. 6 a stock inlet insert 29a is provided with threads at 30 for threading into the housing of the cleaner. The insert ha an inner diameter E to provide a flow passage 28 tangentially into the chamber 27. 
     An alternate insert is shown in FIGS. 7 and 8 having a smaller flow opening 28 of a diameter F. This insert 29b is threaded at 30 for interchangeable insertion into the hydrocyclone housing. 
     A vortex finder overflow opening is provided by an insert 31a. Having a flow opening 32 of a diameter G. An alternate insert is shown in FIGS. 9 an 10 at 31b having a smaller flow opening 32 of a diameter H. The inserts 31a and 31b are each threaded at 33 for interchangeability into the cyclone housing. Additional inserts may be provided of different size openings. 
     A modified form of insert may be provided shown in FIG. 11 wherein a housing insert 31c can be threaded into the opening into the chamber 27. For this arrangement, a single housing is provided and the housing has a central bore for the insertion of sleeves or tubes 35. The tube 35 is pressed into the housing and has a flow opening 36 of a diameter I. A single housing such as 31c may be employed, and to change the diameter of the opening, other tubes or sleeves 37 may be provided. An alternate tube 37 is shown in FIGS. 13 and 14 and has a central opening 38 of a diameter J which is smaller than the diameter I. This arrangement utilizes a simplified structure wherein only one insert may be provided and tubes of substantial number of varying size may be used to obtain the exact flow opening size required. A similar structure may be employed for the insert 29a wherein tubes of different sizes may be selectively used. 
     In use and operation the operator removes the stock entry insert 29a and the overflow opening insert 31a to substitute other inserts of different size openings. Thereby for a given hydrocyclone, the operator can change either the capacity or cleaning efficiency without having to install a new hydrocyclone cleaner. This reduces the capital investment of a plant, and allows for quicker or easier alteration of the operation. Such alteration can readily occur when the quality or quantity of the stock being processed changes so that the capacity and efficiency and overall capability of a plant is enhanced. 
     Thus, it will be seen there has been provided an improved hydrocyclone cleaning arrangement for the cleaning of papermaking pulp which provides a cleaning arrangement offering capabilities heretofore not available except with the changing of the actual cyclone chamber geometry. Field adjustment of the hydrocyclone has been simplified.