US3441141A

US3441141A - Suction filter

Info

Publication number: US3441141A
Application number: US659168A
Authority: US
Inventors: Karl Zimmermann; Carlmax Sturzenegger; Werner Eicher
Original assignee: Ciba AG
Current assignee: BASF Schweiz AG
Priority date: 1965-11-08
Filing date: 1967-08-08
Publication date: 1969-04-29
Anticipated expiration: 1986-04-29
Also published as: DE1551021A1; FR1551021A; GB1190456A; DE1648859B2; DE1648859A1; CH483861A

Description

April 29 1969 K, ZIMMERMANN ET AL 3,441,141

SUCTION FILTER Filed Aug. 8, 1967 Sheet m Tm A M WR IE M M Z w A K CARLMAX STURZENEGGER WERNER EICHER BY WM, zw m ATTORNEYS April 29, 1969 ZMMERMANN ET AL 3,441,141

SUCTION FILTER Filed Aug. 8, 1967 Sheet 3 of 4 INVENTOR KARL ZIMMERMANN CARLMAX STURZE NEGGER' WERNER EICHER ATTORNEYS April 29, 1969 ZMMERMANN ET AL SUCTION FILTER Sheet Filed Aug. 8, 1967 INVENTOR N m M m Du, H E M E w Z E H 1 E m Kzw R U T. S X A M L R m ATTORNEYS April 29,1969 K. ZIMMVERMANN ETAL 3,441,141

SUCTION FILTER Filed Aug. 8. 1967 Sheet 4 of 4 INVENTOR' KARL ZIMMERMANN CARLMAX STURZENEGGER WERNER EICHER ATTORNEYS v United States Patent Office 3,441,141 Patented Apr. 29, 1969 US. Cl. 210-241 8 Claims ABSTRACT OF THE DISCLOSURE A suction filter comprises a container having a liquidpermeable base above and spaced from a base portion of the container, and being tiltable so that filtered material supported on the liquid-permeable base can be removed through an emptying aperture which lies at the lowest point of the container when tilted. An impeller wheel is rotatably mounted within the container and is axially movably towards and away from the liquid-permeable base, the wheel being rotatable in one direction to smooth the filtered material and in the other to shear away portions of the material to permit them to fall under gravity towards the emptying aperture when the container is tilted. The base portion contains an outlet for liquid. The container may have a filling aperture in its upper portion and an emptying aperture which extends over the range of axial movement of the impeller wheel, or may have the shape of an oblique frustocone of which the apex constitutes a filling and emptying aperture. Means for rotating and axially moving the impeller maybe mounted on the container to be tiltable therewith.

This invention relates to a suction filter comprising a tightly closable container having a liquid-permeable intermediate base disposed above its base, in which there is an outlet aperture, and a smoothing device in the form of an impeller wheel displaceable in the direction of its rotational axis arranged above the said intermediate base.

The impeller wheel serves as a device for smoothing over cracks in the cake in order to ensure that it is uniformly processed.

In the case of previously proposed suction filters of this type, the suction-filtered material could not be satisfactorily released. Thus, one previously proposed suction filter has a base capable of being tilted together with the filtration frame away from the remainder of the container. The suction-filtered cake then drops out whole. This is a disadvantage, especially in the case of large suction filters, since the cage may weigh several tons, and the energy involved in the drop requires additional measures. In addition, the long join between the tilting base and the upper part of the suction-filter container is a disadvantage.

According to the present invention there is provided a suction filter, wherein a container has at least one aperture for filling and emptying the container, the, or each such aperture being closable in a pressure-tight fashion, a base portion, an outlet for liquid in said base portion, a liquid-permeable intermediate base disposed across the container so as to lie above and be spaced from the base portion when the container is in an upright filling and filtering position, and means tiltably mounting the container to permit the container to be tilted from said upright position to an inclined emptying position in which said intermediate base lies at an angle to the horizontal and the emptying aperture lies at or near the lowest point of the tilted container, and wherein an impeller wheel is rotatably mounted within the container above (relative to said base portion) the intermediate base, the impeller wheel being mounted so as to be movable in its axial direction towards and away from the intermediate base, and so as to be rotatable in one direction of rotation in which the wheel acts to smooth a filter cake supported on the intermediate base, and in the other direction in which the wheel acts to shear away portions of the cake to permit them to fall under gravity towards the emptying aperture when the container is tilted.

The whole container is desirably tiltable through at least 45, and in the tilted position the intermediate base will lie at an angle of at least 45 to the horizontal, and preferably 60 to In a preferred embodiment of the filter, the container is formed as an oblique frustocone above the region in which the impeller wheel is movable towards and away from the intermediate base, the apex of the frustocone forming a filling and emptying aperture. The whole assembly is capable of being tilted about a horizontal axis extending parallel to the tangential plane of the steepest frustoconegeneratrix which lies preferably normal to the intermediate base, the angle of tilt being at least so great that when the apex of the frustocone is pointing downwards the steepest generatrix is at an angle of at least 45 to the horizontal, and preferably 60 to 80.

In order to enable the invention to be more readily understood, reference will now be made to the accompanying drawings, which illustrate diagrammatically and by way of example, two embodiments thereof, and in which:

FIGURE 1 is a side elevation, partly in section of a suction filter in a filling and working position;

FIGURE 2 is a view similar to FIGURE 1 showing the suction filter of FIGURE 1 in an emptying position;

FIGURE 3 is a side elevation, partly in section, of another suction filter in a filling and working position;

FIGURE 4 is a view similar to FIGURE 3 showing the suction filter of FIGURE 3 in an emptying position; and

FIGURE 5 is a side elevation of the filter shown in FIG-

URES

3 and 4 in an intermediate position.

Referring now to the drawings, FIGURES 1 and 2 and FIGURES 3 to 5 each show a respective embodiment of a tiltable suction filter which consists of a container 1 which is capable of being closed in pressure-tight fashion, and which is mounted so as to be pivotable about a horizontal spindle 3 (FIGURES 1 and 2) or trunnions 3 (FIGURES 3 to 5). The container may be rotated or tilted mechanically or hydraulically about its spindle or trunnions 3 by well known means (not shown). An intermediate base 10, which is made in the form of a filter, is disposed in the lower part of the suction filter container 1. The part of the container disposed above the intermediate base 10 is formed with a filler aperture 6 which is tightly closable by means of a cover 9. The cover 9 may be equipped with a pressureand/ or vacuum connection and an air-discharge union (not shown). Beneath the intermediate base 10* there is a collector space 4 which communicates with an outlet union 11, which is preferably connected for filtering purposes to a vacuum system (not shown). An electric motor 7 is provided for imparting rotation at choice in either direction to an impeller wheel or agitator 8 which can be hydraulically or mechanically lifted and lowered, together with the motor, the whole assembly of motor and impeller wheel being mounted on the container 1.

The impeller wheel 8 is arranged so that its blades smooth the filter cake when the wheel is rotated in one direction and shear the filter cake when the wheel is rotated in the other direction.

In the embodiment illustrated in FIGURES 1 and 2,

the spindle 3 is arranged to one side of the container and the whole filter assembly is capable of being tilted by means of a lifting device (not shown) from the filling and working position illustrated in FIGURE 1 into the emptying position shown in FIGURE 2. In the latter position, the intermediate base 10 and thus the surface of the cake K lie at an angle a of greater than 45 to the horizontal. In the side-wall of the container 1 there is an emptying aperture 13 which is closable by a cover 12, the aperture 13 extending over a height from the intermediate base 10 as far as the highest surface level of the cake K which is reached in practice. As shown in FIG- URE 2, the arrangement is such that, in the tilted position the emptying aperture 13 is adjacent the lowest point of the surface of the intermediate base. In this position, when the impeller wheel 8 is moved in the shearing direction and the cover 12 is opened, the sheared-off material slides over the surface of the cake and drops out of the suction filter container through the aperture 13.

In the embodiment illustrated in FIGURES 3 to 5, the upper part of the suction filter container 1 is in the shape of an oblique frustocone 5, 5' above the region in which the impeller wheel 8 of the smoothing and shearing device is displaceable, the apex of the said frustocone forming the combined filling and emptying aperture 6. The impeller wheel drive including the electric motor 7, etc., is mounted on the fiattest generatrix 5 of the frustoconical upper part of the container. The trunnions 3 are disposed so that the trunnion axis passes approximately through the centre of gravity of the whole assembly which is mounted on a stand 2. In the position illustrated in FIG- URE 4, the steepest frustocone-generatrix 5' is at an angle a of greater than 45 to the horizontal, so that, when the impeller Wheel 8 is actuated in the shearing direction, suction-filtered material scraped off the cake K slides down over the wall 5 and drops out of the suction filter container through the aperture 6.

In a complete filtering cycle using either of the filters just described, the cover 9 is opened and the suction filter is filled in the position illustrated in FIGURE 1 or 3, whereafter the cover 9 is replaced. Filtration then takes place, vacuum being set up beneath the base 10 of the suction filter via the union 11 and/or pressure being set up in the part of the suction filter container above the said base. After the liquid has been sucked away, the filter cake may be washed. For this purpose, washing liquid is introduced through the cover 9, which is again opened. While the filter cake is being sucked dry, the impeller wheel 8 is set is action for smoothing purposes. When the filter cake has been sucked dry, the space 4 beneath the intermediate base '10 is left under vacuum and the suction filter is tilted into the emptying position of FIGURE 2 or 4.

In the embodiment of FIGURES 1 and 2, the cover 12 of the emptying aperture 13 is preferably opened before tilting and while the filter is still in the position shown in FIGURE 1.

In the embodiment of FIGURES 3 to 5, the cover 9 of the emptying aperture 6 is preferably opened in the intermediates position shown in FIGURE 4. Since the space 4 of the suction filter is still under vacuum the suction-filtered cake normally does not come away from the intermediate base 10. The impeller Wheel 8 is now actuated in the scraping direction, and the filtered material is cut out by measured feed to the impeller wheel. Since the intermediate base 10 (FIGURES 1, 2) or the wall portion 5' (FIGURES 3 to 5 leading to the emptying aperture 13 (FIGURES 1 and 2) or 6 (FIGURES 3 to 5) are at an angle of at least 45 to the horizontal, the moist suction-filtered material will fall out through the emptying aperture. In the rare case where the angle of repose of the moist material is greater than 45 it will be necessary either to tilt the filter of FIGURES 1 and 2 through an angle greater than the angle of repose or to use the embodiment of FIGURES 3 to 5. After emptying is finished, the suction filter is returned to the position of FIGURES 1 or 3.

The cover 9 may be equipped with filling, air-discharge, vacuum and/or pressure unions (not illustrated). Filling and the introduction of pressure and washing liquid may then be carried out via these connections with the cover 9 closed. Furthermore, the driving shaft of the impeller wheel 8 may also be made hollow, so that it can act as an inlet pipe, especially for washing liquid.

In the of embodiment of FIGURES 3 to 5, all the operations which might be difficult to effect with the filter in the positions shown in FIGURES 3 and 4 may be carried out in the position shown in FIGURE 5, for example the aforementioned operation of the cover, and coupling and uncoupling of the suspension inlet, washing liquid union, air discharge pipe and gas pressure connection. Maintenance work and any repairs which may be required are also advantageously carried out in the position shown in FIGURE 5. There is therefore no need for any special manhole.

In the emptying position shown in FIGURE 4 of the embodiment of FIGURES 3 to 5, the surface of the suction filtered cake is pivoted through more than 90 from its horizontal position. This ensures satisfactory emptying of all suction filtered materials, particularly those with unfavourable thixotropic properties. The vacuum which is set up beneath the intermediate base 10 While shearing and emptying are in progress prevents the whole filter cake from coming away from the intermediate base.

Any suitable mechanical or hydraulic tilting device of known type may be used for rotating the suction filter, and is therefore not illustrated.

We claim:

1. A suction filter, comprising a container, portions to said container defining at least one aperture for filling and emptying the container, means for closing such aperture in pressure-tight fashion, a base portion to said container, an outlet for liquid in said base portion, a liquid-permeable intermediate base disposed across said container so as to lie above and be spaced from the base portion when the container is in an upright filling and filtering position, means tiltably mounting said container to permit the container to be tilted from said upright position to an inclined emptying position in which said intermediate base lies at an angle to the horizontal and the emptying aperture lies at the lowest point of the tilted container, an impeller wheel rotatably mounted within the container above (relative to said base portion) the intermediate base, means for moving said impeller wheel in its axial direction towards and away from the intermediate base, and means for rotating the impeller in one direction of rotation in which the wheel acts to smooth a filter cake supported on the intermediate base, and in the other direction in which the wheel shears away portions of the cake to permit them to fall under gravity towards the emptying aperture when the container is tilted.

2. The suction filter of claim 1, wherein the container has a filling aperture located in an upper portion thereof remote from said base portion, and an emptying aperture located in a side portion the height of the emptying aperture extending, when the container is in said upright position from said intermediate base to a level where the impeller wheel lies at its greatest distance from the intermediate base.

3. The suction filter of claim 1, wherein said means for rotating the impeller is mounted on the container.

4. The suction filter of claim 1, wherein said mounting means permit the container to be tilted so that said intermediate base lies at an angle of from 45 to to the horizontal.

5. The suction filter of claim 1, wherein above (relative to said base portion) the region over which the impeller wheel is movable towards and away from said intermediate base, the container has the shape of an oblique frustoccone, and wherein the apex of the frustocone is formed as a single filling and emptying aperture, the mounting means being such as to permit the container to be tilted about a horizontal axis so that, when said emptying aperture lies at the lowest point of the tilted container, the steepest generatrix of the frustocone lies at an angle of at least 45 to the horizontal.

6. The suction filter of claim 5, wherein said mounting means permit the container to be tilted so that said steepest generatrix at an angle of from 60 to 80 to the horizontal.

7.- The suction filter of claim 5, wherein said means for rotating the impeller is mounted on the container and includes a drive shaft which passes through the container in the region of the flattest generatrix of said frustocone,

References Cited UNITED STATES PATENTS 8/1897 Mullen 210397 1/1953 Schuller 2l0-399 X SAMIH N. ZAHARNA, Primary Examiner.

JOHN ADEE, Assistant Examiner.

US. Cl. X.R. 210408, 414