US1953237A - Centrifugal separator - Google Patents

Description

Ap 3, 1934. J. KLOTZ CENTRIFUGAL sEPARAToR Filed Nov. 15, 1932 2 Sheets-Sheet l April 3, 1934. 1 KLo-rz y 1,953,237

CENTRIFUGAL sEPARAToR Filed NOV. l5, '195g 2 Sheets-5h68?. 2

Patented Apr. 3, 1934 1,953,237 CENTRIFUGAL snrAnA'ron Josef Klotz, Heidenheim, Wurttemberg, Germany, assigner to American Voith Contact Company, Inc., New York, N. Y., a corporation of New York Application November 15, 1932, Serial No. 642,767 In Germany September 21, 1931 6 Claims.

This invention relates to centrifugal separators,

and has for its general object and purpose to provide certain improvements in machines of the type wherein the centrifuging means is arranged within a fixed cylindrical screen for rotation about a horizontal axis, and which is particularly designed and intended for use in the screening or separation of worthless materials from ground wood pulp, chemical pulp, etc.

It is one of the important objects of the present invention to provide means whereby the screened stock is discharged from the base or bottom of the machine, while at the same time the required pressure upon the material within the machine is adequately maintained.

Centrifugal separators of this character are generally known and are distinguished from other types by the fact that the feed trough for the unscreened stock together with the discharge troughs for the screened stock and the worthless residue, have heretofore been located at a certain level or elevation above the machine and connected with the interior thereof through closed pipes or conduits. Therefore, it is evident that the pressure existing within the machine is dependent upon the static pressure head of the unscreened stock in the feed trough and in the discharge troughs. The prior art construction also necessitates the arrangement of the discharge trough for the screened stock above the machine which, in many cases, results in unfavorable room conditions. This disadvantage is overcome by the present invention.

I attain this object in one embodiment of the invention by arranging around the cylindrical screen plate two spaced cylinders, the inner one of which is provided with an opening at its top through which the screened stock is ejected, while the outer cylinder has a bottom opening through which the stock is discharged from the space between said cylinders into the collection trough.

It is also another important object of the invention to provide simple and efficiently operating means whereby a uniform distribution of the stock from the inlet or feed trough over the entire surface area of the cylindrical screen is obtained. Heretofore, the incoming stoel: following the horizontal axis of the inlet connection, owing to the force of gravity, distributed itself unevenly over the cylindrical screen plate. Thus mass accumulations of the stock at certain points, as at the bottom of the screen cylinder, operated to prevent the uniform screening of the stock. Attempts have been made to overcome this objection by delivering the stock uniformly in spaced jets over the screen plate. It was found, however, that these stock jets were interrupted by the rotating runner blades within the screen cylinder, and resulted in a very appreciable increase in power consumption. Further, the interruption of the stock jets decreased the effectiveness with which they were distributed over the screen plate and resulted only in the whirling of the stock by the runner blades. Thus, the capacity of the screen was appreciably decreased. In other designs, the stock feed inlet has been provided with stationary guide vanes and the runner wheel hub with short ribs for guiding the stock into the screening or separating zone. Such stationary guide vanes, however, offer a very substantial resistance to the flow of the stock current which necessitates a higher static feed pressure with a corresponding increase in stock pressure within the screen. In order to obtain this high static pressure, it is therefore necessary to arrange the feed and discharge troughs at a very high elevation above the separating screen.

My present invention overcomes these disadvantages by the provision of means whereby the entire stock current Within the discharge end of the feed connection is rotated before entering the screen cylinder, and as it enters, the cylinder is diverted from an axial to a radial flow, thereby effecting its uniform distribution over the surface of the cylinder.

With the above and other objects in view, the invention consists in the improved centrifugal separator, and in the form, construction and arrangement of its several parts as will be hereinafter more fully described, illustrated in the accompanying drawings, and subsequently incorporated in the subjoined claims.

In the drawing wherein I have disclosed one simple and practical embodiment of the invention, and in which similar reference characters designate corresponding parts throughout the several views,-

Figure 1 is a vertical sectionalview through one form of apparatus embodying certain features of my present invention;

Fig. 2 is a sectional View taken substantially on the line II-II of Fig. 1;

Fig. 3 is a central vertical section similar to Fig. 2 and illustrating another important feature of the invention; and

Fig. i is a detail sectional View taken substantially on the line IIT-IV of Fig. 3.

Referring in detail to the drawings, the runner wheel a is fixed upon a shaft al extending. 1

on the end wall d communicates and leads to the through a feed inlet opening in one end wall b of a suitable housing with which one end of the stock feed elbow b1 is suitably connected. One end of shaft al extending through the elbow b1 is journalled in a stuiiing box ,b2 and has secured thereto a belt wheel or other suitable drive connection with the source of power.

The opposite end of the shaft a1 is journalled in the stuing box d2 on the other end wall of the housing.

The cylindrical screen c within the housing is suitably mounted and supported in a fixed position upon the housing walls b and d, said screen being entirely open at its opposite ends. With one end of this screen and at the upper side thereof, a vertically extending discharge conduit d1 residue receiving trough indicatedat 1c.

The runner wheel a within the screen cylinder c includes a hub a2 carrying any desirable number of runner blades a3 extending radially from the hub and having their outer edges positioned in closely parallel relation to the inner surface of the cylindrical screen c. Thus, by means of these blades, the stock is centrifugally thrown outwardly and kept in constant motion upon the inner surface of the cylindrical screen plate.V The stock is supplied through the feed elbow b1 from a suitable trough or hopper indicated at i.

n The end walls b and d are rigidly connected with each other below and above the screen c by the plates d3, d4 respectively. The bottom plate d3 forms part of an inner cylinder concentrically Vspaced from the screen c and which also includes the sections e1, e2. These cylinder sections have their upper edges transversely spaced apart and are rigidly xed between the end walls A b and d by any suitable means as indicated at f e3. ,There is thus provided an opening f at the which opens into the trough Z. Thus, the screened stock passing through the opening f into the space between the inner and outer cylinders of the' screen housing is discharged at the bottom of the machinei.

The position of opening f determines the static pressure under which the screening or separating action is effected. Practical tests have shown that in order to obtain the desired result, this pressure need not be very great, so that if the inner housing cylinder is arranged at the customary distance from vthe cylinder screen, the proper screening of the stock under pressure with the screening space always completely filled with the stock, will be fully realized. By the discharge of the screened stock at the bottom of the machine from the space between said inner and outer cylinders, in distinction to prior art machines of a similar type, it is not necessary to locate the receiving trough for the discharged stock, as well as Ythe feed trough and the residue receiving trough above the level of the screen cylinder. Therefore, it is evident that the new construction constitutes a more compact and simple arrangement and results in a substantial saving in space.

In Fig. 3 of the drawings, I have illustrated an additional feature of the invention not shown in Fig. 1, whereby a uniform distribution of the unscreened stock over the entire surface area of the screening cylinder is obtained. As therein shown, the runner wheel hub a2 has a cone shaped end portion extending into the outlet end of the feed elbow b1 and merging into an annular flange or disc a5. This conical end of the wheel hub is provided with a plurality of blades a4 projecting from the surface thereof and extending fromthe shaft a1 to the periphery of the flange a5, the cuter end edges of said blades being disposed closely adjacent to the surface of the cylinder, and preferably at the same distance from shaft al as the edges of the blades a3. The-blades a4 may be the same in number as the blades a3 and disposed in the same radial planes as the latter blades or they may be of greater or less number than the blades a3.

It will be evident from the above description that as the unscreened stock flows into the horizontal discharge end of the elbow b1, it is caught or seized by the blades a4 and forced outwardly thereby. The penetration of these blades into the end of the elbow creates a certain vacuum therein inducing a flow of the stock particles adjacent the walls of the elbow towards the shaft a1. Since these blades a4 extend over the conical end of the hub to the screen cylinder, a uniform distri-- bution of the rotating mass of stock entering the screen cylinder over the hub a to the inner surface of said cylinder is effected. The greater amount of this stock not passing immediately through the screen cylinder is forced in an axial direction inwardly through the space between the periphery of the flange a5 and the wall of the cylinder. Therefore, it is clear that under the pressure of the column of stock in the inlet elbow b1 and trough i, an annular body of the stock of substantially uniform thickness is distributed over the entire inner surface area of the screen cylinder, and is kept in constant rotation relative to said cylinder by the runner wheel blades a3. Therefore these blades will have full effect upon the stock body to force the same through the wall of said screen cylinder.

It will further be seen from the above description that there is no possibility that owing to relative differences in the speed of movement of the stock and of the rotating blades a3, the screening efficiency of the machine will be disadvantageously affected. Since the device eifectually prevents the accumulation of large quantities of thestock at separated points on the inner surface of the screen, clogging of the perforations in the screen plate is obviated. Therefore, a machine equipped with my present improvements, while of very large capacity and output of screened stock, may be operated with the consumption of less power than other machines of this type, and appreciable economy in operation also results from the fact that it becomes unnecessary periodically to stop the operation of the machine for the purpose of cleaning the screen cylinder plate.

From the above description considered in connection with the accompanying drawings, the construction, manner of operation and several advantages of the disclosed embodiment of the invention will be clearly and fully understood. It will be appreciated that I have produced a centrifugal separator of this type, which is very compact in the arrangement of its several parts, and may therefore be produced at low manufacturing cost, while it may be operated at very high speeds and with maximum eficiency. I have herein referred to a practical embodiment of the essential features of my invention which, however, might also be produced in various other alternative structural forms to accomplish substantially the same results. It is therefore to be understood that the privilege is reserved of resorting to all such legitimate changes in the form, construction and relative arrangement of the several elements as may be fairly considered within the spirit and scope of the invention as claimed.

I claim:

1. In a centrifugal separator, having a horizontally positioned cylindrical Ascreen receiving stock under pressure, and revoluble means therein directing the stock under centrifugal force against the screen wall; means external to the screen receiving the screened stock at the top of said screen and directing the same downwardly through a discharge outlet below said screen.

2. In a centrifugal separator, having a horizontally positioned cylindrical screen receiving stock under pressure, and revoluble means therein directing the stock under centrifugal force against the screen wall; a stock supply trough above the screen connected with one end thereof by a feed inlet, a discharge outlet for the residue communicating with the opposite end of said screen at the top thereof and extending upwardly to a receiving trough, and spaced cylinders surrounding said cylindrical screen, the inner cylinder having an opening at the top thereof through which the screened stock passes into the space between said cylinders, and said outer cylinder at the bottom thereof having an opening through which the screened stock is discharged from said space.

3. In a centrifugal separator, a horizontally positioned cylindrical screen, a revolubly mounted shaft extending through said screen, a hub fixed to said shaft within the screen, a plurality of radially disposed blades on one end of said hub, a stock feed inlet opening into one end of said screen, and an additional series of blades on the other end of said hub extending from the shaft to a point closely adjacent to the inner surface of the screen.

4. A centrifugal separator as described in claim 3 in which said additional series of blades extend into the stock feed inlet to produce rotary motion of the stock prior to its admission into the screen.

5. In a centrifugal separator, having a horizontally positioned cylindrical screen receiving stock under pressure, and revoluble means therein directing the stock under centrifugal force against the screen wall; means external to the screen receiving the screened stock at the top of said screen and directing the same downwardly through a discharge outlet below said screen, said last mentioned means comprising concentrically spaced cylinders surrounding said screen, said inner cylinder having an opening at the top thereof through which the screened stock passes into the space between said cylinders, and said outer cylinder having an opening at its lower side for the downward discharge therethrough of the screened stock.

6. In a centrifugal separator, a horizontally positioned screen, feeding means for feeding stock under pressure to the interior of said screen adjacent the axis thereof, revoluble means in said screen for directing the stock under centrifugal force against the screen wall, and outlet means external tc the screen receiving the screened stock at the top of said screen. and directing the same downwardly through a discharge outlet below the screen.

JOSEF KLOTZ.

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