US1952788A - Process and apparatus for continuous centrifugal separation - Google Patents

Description

March 27, 1934. D. w. BERLIN PROCESS AND APPARATUS FOR CONTINUOUS CENTRIFUGAL SEPARATION Filed March 5, 1932 2 *K J 7 w M Patented Mar. 27, 1934 PATENT OFFICE PROCESS AND APPARATUS FOR CONTINU- OUS CENTRIFUGAL SEPARATION David Werner Berlin, 'Rasunda, Sweden Application March a, 1932, Serial no. 596,630

' In Sweden March 20, 1931 2 Claims. (01. 210-69) My present invention refers to a process and an apparatus for continuous centrifugal separation of solids from liquids, of the kind in which the separation is performed in two stages, the

5 first of which consists of a centrifugation wherein the solid particles are brought to be settled against liquid-non-penetrable walls of the rotating drum, whereas the second stage, forming a continuation of the first mentioned one, is performed in a drum, or part thereof, having liquid-penetrable walls.

It has previously been proposed to employ this two-stage centrifugation process for dewatering of moist peat masses, or wet-carbonized peat sludged in water, and the present invention is an improvement of the process and apparatus thus proposed.

The main characteristic of the invention is that the mixture of liquid and solid matter, whether such mixture is of one kind or another, is treated in a centrifugation machine a portion of the drum of which is provided with liquid-non-penetrable walls, whereas another portion thereof is provided with liquid-penetrable walls, and that the material under treatment, simultaneously with the radial centrifugal action, is also subjected to forces caused by mechanical means and tending to convey the material in axial direction within the drum.

3() For this purpose the -machine drum used is provided with a lower portion having non-penetrable walls, and an upper portion having liquidpenetrable walls, a conveyor means being provided within the drum and adapted in axial direction to convey the material therein. It is rather immaterial, however, if one or the other of the portions of the drum referred to is the upper, or lower, one therein, and the apparatus may also be converted so that the lower portion has liquid-penetrable walls and the upper has non-penetrable wall, if desired. In any case, the portion having the liquid-penetrable walls ought to be of a smaller diameter than the other portion of the drum.

A preferred embodiment of the invention is illustrated in the accompanying diagrammatical drawing, in which the single figure at hand is intended to show the centrifugation machine in axial, or longitudinal, section. Without nearer explanations the process forming part of the invention will also be understood from the description of the machine.

In the embodiment shown the machine drum consists of an outer cylindrical, or bell-shaped,

shell 1 provided at both ends with covers 2 and 3,

respectively, and by means of such covers the said shell is rotatably mounted around a central shaft 4 on the sleeve-shaped trunnions 5 and 6. The main lower portion 1 of the 'drum is provided with solid or non-penetrable walls, and 50 the upper portion '7 thereof is of a somewhat reduced diameter in relation to the former and provided with liquid-penetrable walls of one suitable kind or another, the main point being that such walls shall permit the liquid to escape there- 55 through while retaining the solids contained in the material under treatment.

, At the upper end the drum is provided with outlets 8 for the dewatered solid material, and the reduced lowermost end portion 9 of the drum is provided with similar outlets 10 for escape of the liquid constituent separated in the first stage of treatment.

Within the drum, the shaft 4 serves for supporting an inner cylindrical shell member 11 extending to the whole length of the drum and affixed to said shaft so as to rotate together with the same, a helical blade member-12 being exteriorly aflixed to the upper portion of said shell member adapted to convey the material in axial o direction through the drum. A downward extension 13 of the said blade 12 is also of a helical shape but supported at suitable intervals by means of arms 21 extending from the inner shell member 11, so as to form a free space nearest to saidshell member between the same and the blade proper, in order to facilitate the downward motion of the liquid separated in the first stage and adapted to be drained by means of the outlets 10.

The lower end of the drum is supported in a bearing 14 for the hollow trunnion 6, and the shaft 4 is rotatably mounted in the latter. An upper bearing 15 is provided for the hollow trunnion 5, and the upper end of the shaft 4 is also rotatably mounted therein. By means of a gear 16, one wheel of which is mounted on the upwardly extending trunnion 5, the drum 1, 7, 9 is adapted to be rotated from a suitable source of power. The upper end of the shaft 4 extends a 10 little beyond the end of the trunnion 5 and by means of another gear 1'7 the said shaft is also set into rotation.

The shaft 4, having a closed bottom end, is otherwise hollow and adapted to feed in the material to be treated. Such material enters through a fixed pipe 18 positioned at the upper end of the hollow shaft, and passing the latter it enters the interior of the drum by means of a suitable number of transverse pipes 19 penetrating the inner shell member 11. The said pipes 19 are posi- Y to tioned at a level between the upper portion 12 of the blade positioned closely to the inner shell 11, and the lower portion 13 thereof positioned at a little distance from said shell.

The shaft 4 and the trunnion 5 are intended to be rotated in the same direction but at different speeds, so that the shell members 1 and 11 v will get a relative rotation in relation to each other. The material to be treated is fed in through the pipe 18, and passing the hollow shaft 4 and the pipes 19 it will be introduced into the shell 1. The solids will at once be forced outwardly against the drum walls, and the liquids collecting nearer to the axis thereof will freely flow down and escape through the pipes 10. While being subjected to a further centrifugal action, the mass will be conveyed upwardly by the blade 12, 13, and the upper portion 12 thereof due to its helical shape will not prevent a continued downflow of the liquid nearest to the inner shell 11, the solids collecting mainly at the cir cumference of the drum shell 1, as indicated above.

The blade portion 12 conveys the solids throughout the whole axial length of the drum, and when arriving to the conical intermediate portion forming a connection between the upper and lower portions of the drum the material is also subjected to a mechanical press action squeezing out a considerable quantity of the liquid constituent before the material enters the reduced upper portion 7 of the drum. When arriving into said upper drum portion the liquid constituent still at hand is thrown out through the liquid-penetrable walls therein, such action forming the second stage of the treatment, and the separated solid further conveyed upwardly is delivered through the pipes 8 for subsequent treatment according to will.

Naturally the pipes 8 may be substituted by other channel means having a substantial width in circumferential direction in order to facilitate the delivery of the solids. Further it is evident that the lower portion of the shaft 4, i. e. the portion thereof positioned below the pipes 19, need not be hollow, and in case the shaft is hollow to the whole length, the bottom end closure shown in the bearing 14 can be raised into a position a little below the pipes 19, as the lower end of the hollow shaft forms a dead space only. The shells 1 and 11 need not be cylindrical, as aforesaid, and a conical shape or bell-shape will also serve the purpose. Besides the inner and outer shells need not have the same shape, and the inter-space between them can be reduced in the direction towards the delivery end for the solids, if desired.

What I claim and desire to secure by Letters Patent is:--

1. In a centrifugal separator for separating liquids and solids, the combination of a rotatable vertical shaft, a substantially cylindrical casing rotatably mounted thereon and comprising a lower section unpenetrable to liquids and an upper section penetrable to liquids but not to solids positioned in the axial extension of the first-mentioned section, a shell member secured to said shaft and rotatable therewith in said casing, an annular space between said shell member and said casing, inlet means for feeding in a mixture of liquids and solids into said space at the unpenetrable section of the casing, outlet means for liquids adjacent to the bottom of the casing, outlet means for solids adjacent to the top of the casing, a helical conveyor blade arranged in said annular space and carried by said shell member, said conveyor blade comprising a lower portion extending from said inlet means to the bottom of the casing and being spaced from said shell memher to form an inner annular passage for liquids flowing towards the bottom outlet, and an upper portion extending from said inlet means to the top of the casing, said upper portion being of a width substantially equal to the width of the annular space, and means adapted to rotate said shaft and said casing at different speeds for causing the conveyor blade to feed the solids accumulating on the inner surface of the casing in an axial direction thereon towards the outlet at the top of the casing while simultaneously permitting the bulk of liquid separated in the lower portion of the casing to flow straight down to the bottom outlet through said annular passage.

2. In a centrifugal separator according to claim 1, the additional feature that the penetrable section of the casing has a smaller diameter than the unpenetrable section and is connected there with by a conical section, and the shell member is of uniform diameter throughout its length.

DAVID WERNER BERLIN.

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