KR100193751B1 - Centrifuge for Solid and Liquid Separation - Google Patents

Abstract

The present invention relates to a centrifugal separator on which a centrifugal drum is placed on a drive shaft for the solid-liquid separation of the aged suspension. During the centrifugation process the centrifugal drum is closed and the filter cake is formed in the outer circumferential region. Filtrate formed on the filter cake is removed from the centrifugal drum through the outlet. By introducing a displacement means inside the centrifugal drum, the residual liquid remaining on the filter cake is discharged from the inside of the centrifugal drum.

Description

Centrifuge for separating solid and liquid

The invention is a suspension with a drum disposed on a drive shaft, the outer periphery away from the shaft being closed at least during centrifugation so that a filter cake is formed in the outer periphery and an outlet having an outlet for removing the filtrate on the drum. To a centrifuge for separating solids and liquids.

Centrifuges are used, for example, to concentrate slurry or to sort sludge. Through the inlet, a predetermined amount of suspension is transferred to the centrifugal drum, where the solids are separated from the liquid by centrifugal force. The centrifuge solid is accumulated on the outside inside the centrifugal drum to form a so-called filter cake or solid cake. Since the mass of the liquid particles is smaller, a liquid layer almost free of solids is formed on the filter cake.

Since a layer of cloudy or clear liquid known as the filtrate is formed radially inward in the centrifugal drum, the filtrate can be removed by an outlet located radially inward on the filter drum.

During the rotation of the centrifugal drum, the suspension is fed to the extent that the filtrate reaches the filling height exiting the centrifugal drum through the outlet. Suspension feed should be stopped at least until the filter cake reaches the filtrate outlet.

The problem is that residual liquid often remains on a portion of the filter cake surface when the solid interface reaches the filtrate outlet. This problem occurs especially when a process valley is formed on the surface of the filter cake where residual liquid can collect due to the centrifugal drum shape.

In order to prevent the filtrate from being contaminated by the filter cake piece exiting the filtrate outlet at the end of the centrifugation process, in some centrifuges the suspension inlet is stopped when there is still a layer of residual liquid on the filter cake. At the end of the centrifugation process, this residual liquid is discharged with the filter cake so that the filter cake is wetted again by the residual liquid. Thus, this residual liquid lowers the dehumidification of the filter cake and also reduces the recovery rate of the filtrate.

It is an object of the present invention to provide a centrifuge for separating solids and liquids, which can achieve particularly good dehumidification of filter cakes, or particularly high filtration rates.

1 is a cross-sectional view of the final centrifugal state of the centrifuge according to the present invention.

2 is a cross-sectional view when the half drum is moved in the centrifuge of FIG.

* Explanation of symbols for main parts of the drawings

10: centrifuge 11: drum

14 Shaft 16: Filter Cake Collection Chamber

17: filtrate collection chamber 20: drainage

21 sleeve 23 suspension supply

24: filtrate outlet 27: opening space

28: conical inner wall 35: filter cake

36: residual liquid

According to the invention, this object is achieved by sending displacement means into the centrifugal drum prior to discharging the filter cake. The drainage means can be introduced with a fixed centrifugal drum during the centrifugation process or at the end of the centrifugation process. Through the inflatable drainage means, the residual liquid on the filter cake is drained and sent to the outlet side. In addition, the drainage means impart additional pressure on the filter cake so that an additional squeezing or pressing effect can be obtained.

According to a preferred embodiment of the invention, the drainage means is a fluid which can be introduced into the centrifugal drum under pressure. The fluid may be a gas, in particular a compressed gas, or a liquid, ie a dilute liquid solvent. By this fluid, all residual liquid can be discharged from the centrifugal drum regardless of the shape of the filter cake.

According to another preferred embodiment of the invention, the drainage means is a volume expandable shape variable displacement body for discharging residual liquid. In the case of a solid drainage, a clearly defined space in the centrifugal drum is occupied, so that a clearly defined amount of liquid can be drained. In addition, additional high pressure may be formed on the filter cake with the inflatable drainage. After the residual liquid drainage, the drainage may again be in a small volume form. In order to change the shape of the drainage, for example, a lever mechanism can be installed in the drainage.

According to a particularly preferred embodiment of the invention, the drainage body has a sleeve, which is located along the shaft inside the centrifugal drum and is inflated by the pressure medium. The sleeve is made of a pressure-tight material that does not rupture well and may have a bellows structure, for example. The pressure medium can be a fluid that can be introduced into the sleeve through a pressure passage formed along the shaft to increase the volume. When compressed air is used as the pressure medium, the compressed air can be delivered to the surrounding air by the valve after increasing the volume. However, when hydraulic fluid is used as the pressure medium, the fluid is in a closed circuit by the supply and discharge passages.

The contour of the drainage fits exactly to the expected filter cake structure so that it almost fills the entire space between the filter cake and the shaft in the centrifugal drum so that all residual liquid is drained.

As another embodiment of the invention, it is preferred to make the sleeve an elastic body, in particular rubber. As a result, the sleeve can be flexibly applied even when the surface shape and size of the filter cake are different. In addition, the compressed air introduced into the sleeve can be discharged to the sleeve pressure without using an additional pump mechanism.

According to another preferred embodiment of the present invention, after the suspension is fed through the suspension inlet, drainage fluid can be introduced into the centrifuge and the morphological drainage can be placed inside the centrifuge. Through the dual use of such drainage means, residual liquid can be removed extensively from the filter cake surface. Depending on the suitable function, either the drainage fluid or the drainage may be introduced first or the two drainage means may be used simultaneously.

According to another preferred embodiment of the present invention, the centrifugal drum has two half drums and at least one half drum is axially movable on the shaft to form an opening space. During the centrifugation process, the half drums are held in overlapping positions to form a closed centrifugal drum. At the end of the centrifugation one or two half drums are moved axially to form the opening space for the discharge of the filter cake and in particular the centrifugal ejection. Through this opening space, the filter cake falls out of the drum under the action of gravity and is ejected by centrifugal force by rotating the two half drums.

It is preferred according to the invention that the half drum has a conical inner wall that widens towards the opening space. As a result of the inclined shape of the half drum inner wall, the filter cake can be easily discharged from the centrifugal drum. The inner wall may also have a form that extends to another rotationally symmetrical, radially outward direction.

According to another preferred embodiment of the present invention, the axially movable half drum can be moved by a hydraulic mechanism. In particular, double acting hydraulic cylinders can be used.

In another embodiment of the invention, the movable half drum has a ring-shaped recess in the vicinity of the shaft, which recess is divided into two pressure spaces by a circular protrusion of the shaft, in which the hydraulic pressure reaches the pressure space. A passage is provided. By supplying hydraulic fluid to one or another pressure space or chamber, one half drum is movable on the shaft. The sliding surface of the shaft protrusion on the recess of the half drum is pressure-tightly sealed in a conventional manner by sealing or packing. No separate hydraulic cylinder is required for movement on the shaft of the half drum.

In another preferred embodiment of the invention, the filter cake collection chamber is in communication with the opening space and the filtrate collection chamber is in communication with the filtrate outlet. The two chambers are arranged in parallel and surround the opening space or filtrate outlet in the full circumferential direction. Within the two chambers, conventional pumping mechanisms for transporting the filtrate and filter cake out of the centrifuge, such as pumps or feed screws, can be installed.

As another embodiment of the present invention, it is preferred that at least one process space of the centrifuge is surrounded by a closed casing. The process space consists essentially of the centrifugal drum, filter cake collection chamber and filtrate collection chamber. Only passage openings for the supply and discharge lines are located in the casing. Shaft bearings and rotary drives are properly positioned outside the casing.

Hereinafter, the present invention will be described in more detail with reference to Examples and drawings.

1 shows a centrifuge 10 according to the invention with a shaft 14 together with a centrifugal drum 11. In this embodiment, the centrifugal drum 11 essentially comprises a half stationary drum 12 and a half moving drum 13. On the closed front face of the fixed drum 12, a filtrate outlet 24 having a plurality of passage holes is provided.

The filtrate outlet 24 extends from the inside of the centrifugal drum 11 to the filtrate collection chamber 17 on the outside. Next to the filtrate collection chamber 17 is a filter cake collection chamber 16. These two collection chambers 16, 17 form a closed casing 15 around the centrifugal drum 11.

The basic components of the centrifuge 10, such as the bearings 18 and 19 and the drive not shown, are arranged outside the casing 15 in a maintainable manner. The casing 15 and the bearings 18, 19 are arranged in the frame 33.

A drain 20 is disposed along the shaft 14 in the centrifugal drum 11, which has a sleeve 21 fixed to the shaft 14 by a sleeve fixture 26. The pressure medium 22 is introduced into the drain 20 by the pressure passage 22 of the shaft 14.

In the operating position of the centrifuge 10 as in FIG. 1, the drain 20 has an enlarged volume to drain the residual liquid 36 in the centrifugal drum 11 at the end of centrifugation. Fill height 25 at the end of the centrifugation process is indicated by a dashed line. The boundary layer between the formed filter cake 35 and the residual liquid 36 is shown by a dashed-dotted line. Functionally, the drain 20 is expanded around the residual liquid 36 such that the residual liquid is discharged out of the centrifugal drum 11 through the filtrate outlet 24.

In the embodiment according to the invention, the drainage of the residual liquid 36 as additional compressed air is introduced into the centrifugal drum 11 by means of a suspension supply 23 formed in the shaft 14 and having a radial flow path 38. Increases. Therefore, any residual liquid 36 can be drained from the centrifugal drum 11 as a result. The radial flow path 38 is inclined and flows undisturbed to the distribution surface 39 on the moving drum 13. As a result, the introduction of a suspension without turbulence is ensured. For more efficient use of compressed air, the radial flow path 38 is arranged in the region of the centrifugal drum 11 far from the filtrate outlet 24.

Far from inside the centrifugal drum 11, the moving drum 13 has a recess 29 adjacent to the shaft 14. A protrusion 37 of the shaft 14 protrudes into the recess 29 to divide the recess 29 into two separate pressure spaces 30, 31 in a pressure resistant manner.

The hydraulic passage 32 connects the two pressure spaces 30, 31 to the hydraulic mechanism, and the operation of one pressure space 30 or the other pressure space 31 causes the half drum 13 to shaft. (14) can be moved. The hydraulic mechanism, not shown, is connected to the suspension supply, rotary drive and drainage moving means by conventional adjusting means to ensure a reliable operating sequence.

FIG. 2 shows the operating positions in the centrifuge 10 of FIG. 1 in which the half drums 12, 13 are separated from each other to discharge the filter cake. In this operating position, the drain 20 forms a smaller volume with an elastic sleeve 21, such as a hose, rigidly fixed to the shaft 14.

Opening space 27 is formed by separating and moving the two half drums 12, 13, through which the filter cake is discharged into the filter cake collection chamber 16 when the centrifugal drum 11 is rotated. To facilitate filter cake discharge, conical inner walls 28 are formed on the half drums 12, 13. The diameters of the half drums 12, 13 are widened to the opening space 27.

Residual liquid remaining after the end of the centrifugation process may be discharged by using the drainage means according to the present invention, thereby improving the dehumidification level of the filter cake and increasing the filtrate recovery rate.

Claims (10)

A centrifugal drum is placed on the drive shaft, the outer circumference away from the shaft can be closed at least during the centrifugation process to form a filter cake on the outer circumference, and an outlet is provided on the centrifugal drum, through which the filtrate can be removed. In the centrifugal separator for solid and liquid separation of the suspension, the drainage means is disposed inside the centrifugal drum 11 prior to the discharge of the filter cake 35, and the drainage means has a volume for discharging the residual liquid 36. This expandable drainage body 20 is provided with a sleeve 21 which is disposed inside the centrifugal drum 11 along the shaft 14 and expandable by a pressure medium. Centrifuge, characterized in that. A centrifugal drum is placed on the drive shaft, the outer circumference away from the shaft can be closed at least during the centrifugation process to form a filter cake on the outer circumference, and an outlet is provided on the centrifugal drum to remove the filtrate therethrough. In the centrifugal separator for solid and liquid separation of the suspension, the drainage means is disposed inside the centrifugal drum 11 prior to the discharge of the filter cake 35, and the drainage means is moved into the centrifugal drum 11 under pressure. Centrifuge, characterized in that the fluid can be introduced. The centrifuge of claim 1, wherein said sleeve (21) is made of an elastic material. 2. The drain fluid can be introduced into the centrifugal drum 11 after the suspension is supplied by the suspension supply section 23, and a variable drain 20 is provided inside the centrifugal drum 11. Centrifuge, characterized in that. 2. The centrifugal drum (11) according to claim 1, wherein the centrifugal drum (11) has two half drums (12, 13) and the at least one half drum (13) moves axially on the shaft (14) to form the opening space (27). Centrifuge, characterized in that possible. 6. Centrifuge according to claim 5, characterized in that the half drum (12, 13) has a conical inner wall (28) widening towards the opening space (27). 6. Centrifuge according to claim 5, characterized in that the axially movable half drum (13) is movable by a hydraulic mechanism. 6. The movable half drum (13) has a circular recess (29) adjacent to the shaft (14), which recess is defined by the two pressure spaces (D) by the circular protrusion (37) dp of the shaft (14). 30, 31, characterized in that a hydraulic passage (32) is provided in the shaft (14) leading to the pressure space (30, 31). 6. Centrifuge according to claim 5, characterized in that the opening space (27) is in communication with the filter cake collection chamber (16) and the filtrate outlet (24) is in communication with the filtrate collection chamber (17). A centrifuge according to claim 1, characterized in that the working space of the centrifuge (10) is surrounded by a closed casing (15).