US2707420A

US2707420A - Pulp preparing apparatus

Info

Publication number: US2707420A
Application number: US338756A
Authority: US
Inventors: Skardal Karl Arvid; Borjeson Olov Birger
Original assignee: Leje and Thurne AB
Current assignee: Leje and Thurne AB
Priority date: 1952-12-11
Filing date: 1953-02-25
Publication date: 1955-05-03
Anticipated expiration: 1972-05-03

Description

K. A. SKARDAL ET AL PULP PREPARING APPARATUS V May 3, 1955 2 Shets-Sheet 1 Filed Feb. 25, 1955' M 195.5 K. A. SKARDAL EI'AL 2,707,420

PULP PREPARING APPARATUS Filed Feb. 25, 1953 2 Sheets-Sheet 2 United States Patent PULP PREPARING APPARATUS Karl Arvid Skardal, Stockholm, and Olov Birger Biirjeson, Bromma, near Stockholm, Sweden, assignors to Leje & Thurne Aktiebolag, Stockholm, Sweden Application February 25, 1953, Serial No. 338,756 Claims priority, application Sweden December 11, 1952 2 Claims. (Cl. 92--26) The present invention relates to an apparatus for preparing a pulp suitable for supplying it directly or subsequently to some preparatory treatment to a paper making machine.

More particularly, the invention relates to that type of such apparatus which comprises a tank for receiving a liquid and the stock from which the pulp is to be formed, said tank having at its bottom a rotor provided with impeller blades for beating and circulating the contents of the/tank and, eventually, also for discharging the prepared pulp as it reaches a predetermined consistency.

The object of the invention is to provide an apparatus of this type, which may yield a high degree of efliciency and may positively remove such solid elements which are not suitable as ingredients of the prepared pulp.

According to a feature of the invention guiding elements are provided inside the tank for leading the contents of the tank held in a circulation by the rotor in an ascending path in order thereby to obtain a positively controlled and intensified circulation, said guiding elements being so constructed and arranged as not to prevent the return flow of the circulating tank contents downwardly towards the center of the rotor.

Another feature of the invention resides in the provision inside the tank of guiding elements forming a path ascending like a spiral along the rounded, preferably cylindrical circumferential wall of the tank.

A still another feature of the invention resides in the provision at the top of the said guiding path of a, preferably removable, grid structure, like a comb or the like, for catching such coarse or big objects in the tank contents, which remain practically unaffected in the contents as the rest thereof has attained the desired state of fineness. It is to be noted, however, that such a removal of coarse objects may be made whenever desired during the operation of the apparatus.

In the accompanying drawings one form of the invention is illustrated.

Figure 1 is a side elevation of the apparatus and Fig. 2 is a top plan view thereof.

Figs. 3-8 are detail sections taken on the lines 3-3, 4-4, 5-5, 66, 77 and 8-8, respectively, of Fig. 2.

It is understood that the construction shown and hereinafter described is an example only, and that variations may be made within the scope of the invention as claimed.

In the example shown the numeral 1 indicates the circumferential wall of a cylindrical tank having a funnelshaped bottom 3 tapering towards an eccentrically positioned circular opening 2. In said opening a rotor is dis posed, though it may, if desired, be disposed above the opening. The rotor may comprise a circular disc 4 supported by a depending vertical shaft 20. Provided on the upper surface of disc 4 is a set of impeller blades 5. Similar blades may be provided also in the lower surface of the disc in order to allow the rotor to be used also as a pump wheel. To this end there may be provided a pump housing 6 having an outlet indicated at 2,707,420 Patented May 3, 1955 6 in Fig. 1. As far as the invention claimed is con cerned the construction of the rotor may be varied, provided it may produce a beating and circulating action on the contents of the tank.

In the example shown the diameter of the opening 2 is considerably greater than that of the disc 4 for the purpose of mounting the rotor in the casing 6'. The annular space thus resulting between the circumference of the disc 4 and that of the opening 2 is covered by an annular plate 7 except for a narrow circular gap 8 immediately surrounding the disc 4, as indicated in Fig. 2.

The rotor due to the eccentrical location of the opening 2 is situated not far from the circumferential wall of the tank. The portion of the rotor next to said wall is covered by a heliciform casing which is open inwardly and towards the rotor center and forwardly in the direction of rotation of the rotor. Said heliciform casing may comprise, for instance, an upper Wall 9 ascending in an oblique direction from the bottom of the tank and a curved side wall It extending from a point 11 of the bottom of the tank near the opening 2 of a point 12 at a higher level of the funnel-shaped bottom, see especially Fig. 6. Extending from another point 13 adjacent the opening 2 which is located in front of the forwardly directed outlet end of the

heliciform casing

9, 10 at a certain distance therefrom, as shown in Fig. 2, is a guide wall 14 forming a helical ascent along the circumferential wall 1 of the tank. The peripheral extension of said guide wall is about half the circumference of the tank.

Rotatably mounted in a bearing 19 at the upper edge of the tank wall 1 is a shaft 15 which extends inwards in a substantially horizontal and radial direction and carries a set of pins 16 which form a grid or comb like structure in front of the discharge end of the guide wall 14. The pins are preferably curved towards the discharge end of the guide wall, as shown in Fig. 3, to allow them easily to catch coarse or big solid objects sliding up along the guide wall. Externally of the tank the shaft 15 is provided with a control mechanism including a handle 17, by means of which the grid or comb structure 16 may be swung upwards for discharging the material caught thereby. Said control mechanism also includes means, as indicated at 18 in Fig. 2, for locking the shaft 15 with the pins 16 in their depending or raised position.

The operation is as follows: The impeller blades 5 of the rotor 4 beats and circulates the contents of the tank, which consists of a liquid, as water, and various kinds of paper-making material, as pieces of ordinary paper pulp or waste paper. The

heliciform casing

9, 10 catches the circulating contents as it is beaten by the impeller blades and set in motion thereby, and leads it onto the guide wall 14, whereby the contents of the tank receives an, at least partially, positively controlled circulation, while still quite free to flow downwards from the top of the tank towards the center of the impeller wheel to be then again beaten and thrown out to be caught by the heliciform casing. The paper-making material of the circulating contents of the tank will, as a result, he more effectively broken up than would be the result of a quite free circulation.

The charging of the tank may be either intermittent or continuous. When continuous charging is used the catching grid or comb 16 is lowered to a position in front of the discharge end of the guide wall 14, either as the pulp prepared has attained a predetermined state of fineness or otherwise, whenever it may be desired to catch and remove solid objects not sufliciently broken up. The removal of the objects caught is effected by swinging the grid or comb 16 upwards and outwards over the edge of the tank. In case of continuous charging the operation of the grid or comb 16 may take place at suitable intervals.

Attention is again invited to the fact that variations may be made without departing from the scope of the annexed claims.

We claim:

1. An apparatus for preparing a pulp for paper manufacturing, comprising a tank including a substantially cylindrical side wall and a bottom wall for receiving a liquid and material to be mixed with the liquid for preparing a paper stock, an impeller eccentrically mounted at the bottom of said tank adjacent the side Wall thereof for beating and circulating the stock, a heliciform housing surrounding the portion of said impeller situated next to the side wall of the tank for re ceiving and guiding a portion of the stock discharged from the impeller, a spiral ramp extending along a portion of the side wall. of the tank from a point at the bottom of the tank in front of the delivery end of said heliciform housing to a point not far from the top of the tank for receiving the material delivered from said housing and allowing it to rise along the upper surface of the ramp to about the level of the stock in the tank, and means in front of the upper end of the ramp for catching coarse objects carried with the material that leaves the ramp at the upper end thereof.

2. An apparatus for preparing a pulp for paper manufacturing comprising a tank including a cylindrical side wall and a bottom tapering towards an eccentrically positioned circular opening, an impeller wheel rotatably mounted in said opening, a heliciform housing provided between the portion of said impeller which is situated next to the side wall of the tank, said heliciform housing having a side wall forming a smooth transition to the side Wall of the tank, a spiral ramp provided along a portion of the side wall of the tank for constituting a path gradually rising from the bottom of the tank in front of the delivery end of said heliciform housing up to a level not far from the top of the tank, and means rotatively mounted in the side Wall of the tank in front of the upper end of the ramp for catching coarse objects p, carried along the upper surface of the ramp. by the stock passing upwardly along said surface.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

1. AN APPARATUS FOR PREPARING A PULP FOR PAPER MANUFACTURING, COMPRISING A TANK INCLUDING A SUBSTANTIALLY CYLINDRICAL SIDE WALL AND A BOTTOM WALL FOR RECEIVING A LIQUID AND MATERIAL TO BE MIXED WITH THE LIQUID FOR PREPARING A PAPER STOCK, AN IMPELLER ACCENTRICALLY MOUNTED AT THE BOTTOM OF SAID TANK ADJACENT THE SIDE WALL THEREOF FOR BEATING AND CIRCULATING THE STOCK, A HELICIFORM HOUSING SURROUNDING THE PORTION OF SAID IMPELLER SITUATED NEXT TO THE SIDE WALL OF THE TANK FOR RECEIVING AND GUIDING A PORTION OF THE STOCK DISCHARGED FROM THE IMPELLER, A SPIRAL RAMP EXTENDING ALONG A PORTION OF THE SIDE WALL OF THE TANK FROM A POINT AT THE BOTTOM OF THE TANK IN FRONT OF THE DELIVERY END OF SAID HELICIFORM HOUSING TO A POINT NOT FAR FROM THE TOP OF THE TANK FOR RECEIVING THE MATERIAL DELIVERED FROM SAID HOUSING AND ALLOWING IT TO RISE ALONG THE UPPER SURFACE OF THE RAMP TO ABOUT THE LEVEL OF THE STOCK IN THE TANK, AND MEANS IN FRONT OF THE UPPER END OF THE RAMP FOR CATCHING COARSE OBJECTS CARRIED WITH THE MATERIAL THAT LEAVES THE RAMP AT THE UPPER END THEREOF.