US3503591A

US3503591A - Mixing apparatus

Info

Publication number: US3503591A
Application number: US702580A
Authority: US
Inventors: Karl Erik Bergstedt
Original assignee: Sunds AB
Current assignee: Valmet AB; SUNDS SUNDSBRUK AB
Priority date: 1967-02-27
Filing date: 1968-02-02
Publication date: 1970-03-31
Anticipated expiration: 1987-03-31
Also published as: GB1212596A; NO122970B; SE348379B; FR1565516A; DE1632417B2; FI50067B; US3606272A; FI50067C; DE1632417A1

Description

March 31, 1970 K. E. BERGSTEDT 3,503,591

MIXING APPARATUS Filed Feb. 2, 1968 2 Sheets-Sheet 1 March 31, 1970 K. E. BERGSTEDT I 3,

MIXING APPARATUS Filed Feb. 2, 1968 2 Sheets-Sheet 2 United States Patent U.S. Cl. 259-25 6 Claims ABSTRACT OF THE DISCLOSURE The apparatus according to the invention comprises a container for receiving the material, said container being provided with at least one inlet, debouching into the interior of the container and intended for material, and at least one outlet for treated material. The substantial characteristic features of the apparatus consist therein that within the container there is provided, on one hand, at least One pump means, preferentially in the shape of a pump wheel, said pump means communicating with the inlet for the material, and on the other hand, a casing, entirely or substantially entirely enclosing the pump wheel and preferably being in the shape of a sleeve, said casing being adapted to receive and to direct the flow of material, generated by the pump wheel, towards a platelike surface, provided within the container or formed in the wall proper of the container, said surface extending substantially at right angles to the direction of movement of the fiow of material and/or to the axial direction of the sleeve-like casing, and also at least one means extending into the container and serving for supplying chemicals to the material introduced into the container.

U.S. Patent No. 3,334,868 discloses an apparatus for mixing different materials with each other, said apparatus substantially comprising on one hand a container for receiving the materials to be mixed, said container having laterally located outlet means and centrally located inlet means, and comprising on the other hand pump means, the inlet of which is connected to said outlet means and the outlet of which is connected to said inlet means. In the apparatus in question there are provided members for directing the jet of material, which is to be returned to the container, in a free jet in a path, which is, at least approximately directed at right angles to the axis of the container. Due to the fact that the pump assembly in the apparatus in question is located outside the container for the material to be treated and due to the existence of external pipe lines the apparatus requires rather much space and also is rather expensive to manufacture.

The present invention relates to a mixing apparatus which requires less space and is cheaper to manufacture than the apparatus mentioned above. Also, in the new apparauts the conditions of flow and the technical-mixing properties are extremely good. The apparatus is particularly well suited for suspensions, sludges or the like, preferentially with the simultaneous admixing of gaseous or liquid chemicals to a suspension of cellulose pulp having a consistency of 0.5-

The apparatus according to the invention comprises a container for receiving the material, said container being provided with at least one inlet, debouching into the interior of the container and intended for material, and at least one outlet for treated material. The substantial characteristic features of the apparatus consist therein that within the container there is provided, on one hand, at least one pump means, preferentially in the shape of a pump wheel, said pump means communicating with the inlet for the material, and on the other hand, a casing, entirely or substantially entirely enclosing the pump wheel "ice and preferably being in the shape of a sleeve, said casing being adapted to receive and to direct the flow of material, generated by the pump wheel, towards a plate-like surface, provided within the container or formed in the wall proper of the container, said surface extending at right angles, or substantially at right angles, to the direction of movement of the flow of material and/or to the axial direction of the sleeve-like casing, and finally also at least one means extending into the container and serving for supplying chemicals to the material introduced into the container.

These and other characteristic features of the invention will appear from the following detailed description of two embodiments, reference being had therein to the accompanying diagrammatical drawing figures.

FIGURE 1 illustrates a longitudinal cross sectional view of a mixing apparatus according to the first embodiment, FIGURE 2 showing an end view of said same apparatus, when viewed from that side on which the material to be treated is supplied to the apparatus. FIGURE 3, on an enlarged scale, shows a section taken along the line III-III of FIGURE 1 and FIGURE 4 shows a longitudinal cross sectional view of the fore end of a means for supplying chemicals to the material to be treated. FIGURE 5 illustrates an end view of the apparatus according to FIGURE 4 and FIGURE 6, finally, a longitudinal cross sectional view of the modified part of the apparatus according to said second embodiment.

Reference numeral 1 indicates a closed, or substantially closed, container having built in therein a pump device in the shape of an axial pump wheel 2. The section duct of the pump consists of an annular chamber or slot 3 located within the container, the opening of said chamber or slot having the same size along its whole extension so as to provide for an entirely symmetrical suction. The outlet of the pump is shaped as a tube or a sleeve-like casing 4 surrounding the pump wheel 2. The tube 4 preferably is located centrally in the container 1 having its axis coinciding with the axis of the pump wheel and/or with that of the container and, furthermore, is shaped with a narrowing outlet opening, in order that the velocity of the jet of material pumped through the tube shall be accelerated towards said outlet. In front of the .outlet opening of the tube 4 there is provided a surface having a circular circumference, the jet leaving the tube being directed against said surface. Said surface, which may consist of a circular or annular plate 5, preferably is secured to the wall of the container, and the length of the tube 4 preferably is adapted in such a manner that the distance etween the mouth of the tube and the plate 5 amounts to 0.2-2, for example to 0.5-1.5 and preferably to about 1.0 times the diameter of the mouth of the tube. The surface 5 may also be formed from the very wall of the container. The pump wheel 2 is supported by a shaft 6, resting in the bearings 8 mounted in a bearing housing 7. The bearing housing 7 is, in its turn, supported by a bracket 9, which by way of a flange 10 is screwed fast to one end flange of the container 1. By means of guide rails 11 the flange 10 is rigidly connected with the tube 4 surrounding the pump wheel 2 and, consequently, serves as a supporting flange for said tube. In order to provide for a seal between the shaft 6 of the pump and the end wall of the bracket 9 there is provided a packing member 12 of a conventional kind. The pump wheel (the propeller) 2 is adapted to be driven by means of a drive means, not shown, said drive means being adapted to be connected to the free end 16 of the shaft 6, said free end being provided with key way grooves. Preferably the container 1 may be provided with, as a suggestion, two supporting brackets 17 and one short pipe 18 for cleaning.

If also chemicals are to be supplied to the material in connection with the treatment in the container 1, the mixing apparatus may be provided with a separate means serving this purpose. Said means comprises, substantially, a tube 19 extending through the wall of the container and through the plate opposing the tube 4, said tube, with its end located within the container, debouching into the tube 4. In order to facilitate the flowing, when the flow of material within said tube 4- meets the flow of chemicals from the tube 19, there is provided a conical guide wall 20 on the latter (FIGURE 4), so that the outflow of chemicals from the tube 19 is caused to take place through a peripheral slot 21. Also the flow of material moved forward by the pump wheel 2 should encounter a guide surface which is suitably shaped in point of fiow. For that purpose it is suitable to terminate that end of the tube 19, which is turned towards the pump wheel, by a conical portion 22, which together with the guide wall 20 is supported by plate steel members 23 secured to the tube 19.

In the first place the mixing apparatus according to the invention is meant to be operated continuously, in which case non-treated material is supplied to the container 1 through a pipe 13 and is removed from the container through a pipe 14. The supply pipe 13 is located in the end wall of the container 1 near the suction duct 3 of the pump means. Between the inlet of the pipe 13 and said suction duct there is provided an intermediate wall 15 forming a duct or passage arranged on one hand to guide the entering material directly into the pump means and, on the other hand, to prevent any part of the material from flowing directly to the outlet-pipe 14. The

pipes

13 and 14 are located in one and the same radial plane, by which the flow in a plane, perpendicular to the axis of the container 1, becomes fully symmetrical.

The mode of operation of the apparatus is as follows: The material supplied through the pipe 13 is first mixed, within the pump means, with the material circulating within the container 1, as indicated by the arrows abcd, by the action of the pump means. At the mouth of the tube 4, or at some distance from the pump wheel (the propeller) 2, the-chemicals are added and there is generated, at the said mouth, due to the velocity of the jet of material and the diversion thereof against the plate 5, a strong turbulence which causes effective mixing of the material and the chemicals with each other. On diverting the jet against the plate 5 also surrounding material is sucked in and a circulation, as indicated by the arrows a, is obtained. The capacity of the pump wheel (the propeller) 2 should be of an order amounting to 1-10 times, preferably 37 times and preferentially 4-6 times the amount of material flowing through the

pipes

13 and 14. The material entering the container is then caused to circulate a great number of times before leaving the container through the pipe 14.

The alternative embodiment, shown in FIGURE 6, involves that the material to be treated is introduced into the container around the mouth of the tube 4, i.e. on the outside of the pipe. In that case there is, in the end wall of the container and at a distance from said mouth, provided an annular slot 24, which is coaxial with the tube 4. The material is supplied to the slot through the short pipe 25 and the chemicals are supplied through the pipe 26. The pipe 26 extends some disance into the tube 4 and is provided with discharge openings 27. The portion 28, located inside the slot 24, has the same function as that pf the plate 5 in the embodiment shown in FIGURE 1,

The flow within the container will take place substantially in the way indicated by the arrows e g.

As already mentioned the apparatus according to the invention presents extremely good properties in respect of flow and mixing. Primarily this is due to the fact that material, pumped into the container, while circulating therein is, wholly or partly, returned to the pump means.

What I claim is:

1. Apparatus for mixing suspensions of materials, while admixing chemicals therewith comprising a container, inlet means for supplying the material to the container, outlet means for withdrawing treated material therefrom, a sleeve shaped casing located internally of said container and having an inlet and an outlet at opposed ends thereof in communication with the inside of said container, the outlet being spaced from a plate-like surface on the inside of said container, a pump means including an impeller rotatably mounted within the inlet end of said sleeveshaped casing for impelling material from the inlet to the outlet thereof and against said plate-like surface, a supply pipe for chemicals passing into said container and substantially coaxially into the outlet end of said sleeveshaped casing and discharge means at the end of said pipe for uniformly distributing chemicals into the material being impelled through said sleeve-shaped casing.

2. Apparatus as claimed in claim 1 wherein the discharge means comprises a surface disposed at an angle to the axis of said pipe for diverting the flow of chemicals from said pipe into said sleeve-shaped casing.

3. Apparatus as claimed in claim 1 wherein the inlet means for supplying the material comprises an annular opening surrounding said plate-like surface on the inside of said container, said annular opening having a greater diameter than the diameter of the outlet end of said sleeveshaped casing.

4; Apparatus as claimed in claim 1 wherein the pump means has a capacity of from 4 to 6 times the capacity of the inlet means for supplying material to the container.

5. Apparatus as claimed in claim 1 wherein the cross sectional area of the outlet of said sleeve-shaped casing is less than the cross sectional area of the inlet end thereof.

6. Apparatus as claimed in claim 1 wherein the inlet means for supplying the material to the container passes said material directly to the inlet end of said sleeve-shaped casing.

References Cited UNITED STATES PATENTS 3,334,868 8/1967 Lage 259-4 1,733,244 10/1929 Smith 259-97 2,474,592 6/1949 Palmer 259-97 XR 3,027,243 3/1962 Stratford 25997 XR 3,276,753 10/1966 Solt et al. 259-4 XR 3,297,305 1/ 1967 Walden 259-4.-

FOREIGN PATENTS 125,227 11/1931 Austria.

WALTER A. SCHEEL, Primary Examiner JOHN M. BELL, Assistant Examiner US.- Cl- X-R, 259-7, 23, 97