centrifuge

Abstract

To provide a centrifuge that can capture fine particles with a particle size smaller than the size of the pores formed in the filter, regardless of the size of the pores formed in the filter. [Solution] A centrifugal separator comprising a basket 1 with numerous perforations formed on its circumferential surface, a filter 2 disposed along the inner circumferential surface of the basket 1, a screw 3 disposed inside the basket 1 and having screw blades 31 on its outer circumferential surface, and a slurry pipe 4 that supplies slurry and opens opposite the bottom of the basket 1, wherein the filter 2 consists of a first filter 21 disposed along the inner circumferential surface of the basket 1 and a second metal filter 22 disposed along the inner circumferential surface of the first filter 21, and the first filter 21 is made of a filter with a mesh size that captures solid components that have passed through the second filter 22.

Description

[Technical Field]

[0001] The present invention relates to a centrifugal separator that supplies slurry into a rotating basket and separates the slurry into a liquid component and a solid component (cake) by the centrifugal force generated by the rotation of the basket. [Background technology]

[0002] In the chemical, pharmaceutical, and food industries, centrifuges have been commonly used for solid-liquid separation (see, for example, Patent Documents 1 and 2).

[0003] As shown in Figure 3, this centrifugal separator consists of a bottomed basket 1 with numerous perforations formed on its circumferential surface, a filter 2 arranged along the inner circumferential surface of the basket 1, a screw 3 arranged inside the basket 1 and having screw blades 31 on its outer surface, a slurry pipe 4 for supplying slurry and a cleaning liquid pipe 5 for supplying cleaning liquid, arranged so as to be substantially aligned with the central axis of the basket 1 and opening opposite the bottom of the basket 1, and distributors 32, 33, and 34 extending from the screw 3 to guide the slurry and cleaning liquid supplied from the slurry pipe 4 and cleaning liquid pipe 5 into the space formed between the inner circumferential surface of the basket 1, i.e., between the filter 2 and the outer circumferential surface of the screw 3. Then, the basket 1 and screw 3 are rotated by the rotary drive mechanism 6 at the required rotational speed (in this case, the rotational speed of screw 3 is usually set slightly higher than the rotational speed of basket 1), and the slurry is supplied from the slurry pipe 4 to the inner surface of basket 1 via the distributor 32, that is, to the space formed between the filter 2 and the outer surface of screw 3. The slurry supplied to the space formed between the filter 2 and the outer surface of screw 3 collides with the filter 2 due to the centrifugal force acting on basket 1, and only the liquid components that pass through the filter 2 are discharged through the perforations formed on the circumferential surface of basket 1. On the other hand, the solid components captured on the inner surface of filter 2 are discharged from basket 1 and, at a rotational speed of several min -1The screw blades 31 of the screw 3, which rotates in a differential state, act to transfer the material towards the open end of the basket 1, where it is discharged as a dewatered cake. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-128157 [Patent Document 2] Japanese Patent Publication No. 2002-346435 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, the size of solid components that can be captured by filter 2 depends on the size of the numerous slit-shaped or circular pores formed in filter 2 for solid-liquid separation. With commonly used filters 2, the size of solid components that can be captured by filter 2 is approximately 50 μm or larger, and it has been practically difficult to perform stable solid-liquid separation for solid components smaller than this. Furthermore, filters 2 capable of capturing small-particle solid components (fine particles) are expensive, and because the pore size is small, they are prone to clogging, resulting in the problem of requiring a lot of maintenance effort.

[0006] This invention was made in view of the above circumstances, and aims to provide a centrifuge that can capture fine particles with a particle size smaller than the size of the through-pores formed in the filter, without depending on the size of the through-pores formed in the filter. [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides a centrifugal separator comprising a basket having numerous perforations formed on its circumferential surface, a filter disposed along the inner circumferential surface of the basket, a screw disposed inside the basket and having screw blades on its outer circumferential surface, and a slurry pipe that supplies slurry and opens opposite the bottom of the basket, wherein the filter consists of a first filter disposed along the inner circumferential surface of the basket and a second metal filter disposed along the inner circumferential surface of the first filter, and the first filter is configured as a filter with a mesh size that captures solid components that have passed through the second filter.

[0008] In this case, the first filter may be made of fiber.

[0009] Furthermore, the first filter may be made of a sintered wire mesh.

[0010] Furthermore, the solid components captured by the first filter and filling the pores of the second filter can constitute a filtration layer.

[0011] Furthermore, the inclination angle of the inner surface of the basket and the outer surface of the screw blades of the screw with respect to the central axis can be set to 0 to 10°.

[0012] Furthermore, the distance between the filter surface and the outer surface of the screw blades can be set to 0.5 to 1 mm.

[0013] Also, the rotational speed difference between the basket and the screw is 1-10 min -1 This can be achieved by setting it to [this].

[0014] Furthermore, the line width of the tip surface of the screw blades can be set to 0.5 to 1 mm. [Effects of the Invention]

[0015] According to the centrifuge of the present invention, the filter is composed of a first filter disposed along the inner peripheral surface of the basket and a second metal filter disposed along the inner peripheral surface of the first filter. By configuring the first filter with a mesh width capable of capturing solid components that have passed through the second filter, it becomes possible to capture fine particles having a particle size smaller than the size of the through-holes formed in the second filter, without depending on the size of the through-holes formed in the second filter.

Brief Description of the Drawings

[0016] [Figure 1] It is an explanatory diagram showing an embodiment of the centrifuge of the present invention. [Figure 2] It is an explanatory diagram of the main part of the centrifuge. [Figure 3] It is an explanatory diagram showing a conventional centrifuge.

Modes for Carrying Out the Invention

[0017] Hereinafter, embodiments of the centrifuge of the present invention will be described based on the drawings.

[0018] Figs. 1 to 2 show an embodiment of the centrifuge of the present invention. This centrifuge, similar to a conventional centrifuge, includes a bottomed basket 1 having a large number of through-holes formed on its circumferential surface, a filter 2 disposed along the inner peripheral surface of the basket 1, a screw 3 having screw blades 31 on its outer peripheral surface and disposed inside the basket 1, and a slurry pipe 4 disposed so as to substantially coincide with the central axis of the basket 1 and opening towards the bottom of the basket 1 for supplying slurry, and a cleaning liquid pipe 5 for supplying cleaning liquid. It is composed of distributors 32 and 34 extending to the screw 3 for guiding the slurry and the cleaning liquid supplied from the slurry pipe 4 and the cleaning liquid pipe 5 to the space formed between the inner peripheral surface of the basket 1, that is, between the filter 2 and the outer peripheral surface of the screw 3.

[0019] ​Furthermore, in this centrifuge, the filter 2 consists of a first filter 21 arranged along the inner surface of the basket 1 and a second metal filter 22 arranged along the inner surface of the first filter 21, and the first filter 21 is made of a filter with a mesh size that captures solid components that have passed through the second filter 22.

[0020] The first filter 21 can be a fiber filter made of woven, knitted, or nonwoven fabric, or a sintered wire mesh made by sintering multiple layers of wire mesh. Fiber filters can be made of woven fabric (twill weave, plain weave, satin weave, etc.) made of synthetic fibers such as polypropylene fibers, polyester fibers, and polyamide fibers (although not particularly limited, for example, material: polypropylene, weave: twill weave, air permeability: 60 cm). 3 / cm 2 A woven fabric made of synthetic fibers with a density of / min can be used. Furthermore, sintered wire mesh can preferably be made of stainless steel, nickel steel, various alloys, etc.

[0021] The second filter 22 can be made of a material having wear resistance and corrosion resistance, such as stainless steel, nickel steel, titanium, or various alloys, and can be made of a thin sheet material (not particularly limited, but for example, perforated metal with material: SUS316L, hole diameter: φ3 mm, and aperture ratio: 51%) which has countless slit-shaped or circular through-holes formed by punching, etching, electron beam processing, etc. Incidentally, in this centrifuge, the size of the solid components that can be captured by filter 2 does not depend on the size of the numerous slit-shaped or circular pores formed in the second filter 22. Therefore, a metal filter commonly used in conventional centrifuges can be suitably used for the second filter 22.

[0022] The first filter 21 and the second filter 22 may be placed in the basket 1 as separate components, or the first filter 21 may be attached to the second filter 22, or the first filter 21 and the second filter 22 may be bonded or welded together to form a single unit which may then be placed in the basket 1.

[0023] The shape of the inner surface of the basket 1 and the shape of the outer surface of the screw blades 31 of the screw 3 disposed inside the basket 1 are not limited to those of this embodiment (inclination angle θ = 0°). Depending on the properties of the slurry used for solid-liquid separation, for example, the inclination angle θ of the inner surface of the basket 1 and the outer surface of the screw blades 31 with respect to the central axis can be arbitrarily set in the range of 0 to 30° or more. However, in order to allow for a longer slurry residence time, it is preferable to set it to 0 to 10°, more preferably to 0 to 5°. In this way, by setting the inclination angle θ to a small angle, it is possible to stably perform solid-liquid separation of slurries that contain fine particles, which would otherwise require a long time for solid-liquid separation.

[0024] The distance (clearance) between the surface of filter 2 (second filter 22) and the outer surface of the screw blade 31 of screw 3 should be set to approximately 0.5 to 1 mm. If this distance (clearance) is less than 0.5 mm, the filter 2 (second filter 22) and the screw blades 31 of the screw 3 are more likely to come into contact. Also, if it is greater than 1 mm, a large amount of dewatered cake (solid matter) remains on the surface of the filter 2, resulting in a lower yield.

[0025] The tip of the screw blade 31 of screw 3 is formed to be acute, and the line width of the tip surface is Set it to approximately 0.5 to 1 mm. If this line width is less than 0.5 mm, durability will decrease due to wear. Conversely, if it is greater than 1 mm, friction with the dewatered cake will increase, making the particles of the dewatered cake (solid content) more susceptible to breakage.

[0026] Next, I will explain how to use this centrifuge. The basket 1 and screw 3 of the centrifuge are driven by a rotary drive mechanism 6 consisting of a reduction gear to the required rotational speed (usually several thousand mins per hour). -1 (Specifically, 2000-5000 min) -1.). In this case, usually, the rotational speed of the screw 3 is set to be slightly higher than the rotational speed of the basket 1.). While rotating, the slurry is supplied from the slurry pipe 4 through the distributor 32 into the space formed between the inner peripheral surface of the basket 1, that is, between the filter 2 and the outer peripheral surface of the screw 3. The slurry supplied into the space formed between the filter 2 and the outer peripheral surface of the screw 3 collides with the filter 2 due to the centrifugal force acting on the basket 1, and only the liquid component passing through the filter 2 is discharged through the through-holes formed on the peripheral surface of the basket 1. On the other hand, the solid components captured on the inner peripheral surface of the filter 2 are transferred toward the open end of the basket 1 by the action of the screw blades 31 of the screw 3 rotating in a differential state (specifically, 1 to 10 min -1 (specifically, 1 to 10 min -1 , preferably 1 to 5 min -1 , more preferably 1 to 2 min -1 ) and discharged as a dewatered cake. Thus, by setting the rotational speed difference to several minutes -1 , particularly, the solid-liquid separation of a slurry that requires time for solid-liquid separation due to containing fine particles can be stably performed.

[0027] At this time, by passing through the through-holes of the second filter 22 constituting the filter 2 and being captured by the first filter 21, the solid components sequentially filling the through-holes of the second filter 22 can capture fine particles having a particle size smaller than the size of the through-holes formed in the second filter 22, for example, about several micrometers in particle size, without depending on the size of the through-holes formed in the second filter 22 by constituting a filter layer. In addition, since the filter layer composed of the solid components filled in the through-holes of the second filter 22 is not scraped off by the screw blades 31 of the screw 3, fine particles can be stably captured.

[0028] The centrifugal separator of the present invention has been described above based on its embodiments. However, the present invention is not limited to the configuration described in the above embodiments, and its configuration can be modified as appropriate without departing from the spirit of the invention. [Industrial applicability]

[0029] The centrifugal separator of the present invention can be suitably used for separating solid components consisting of fine particles from liquid components. [Explanation of Symbols]

[0030] 1 Basket 2 filters 21 First filter 22 Second filter 3 screws 31 Screw Feather 32, 33, 34 Distributors 4. Slurry pipe 5. Cleaning liquid pipe 6. Rotary drive mechanism

Claims

1. A centrifugal separator comprising a basket having numerous perforations formed on its circumferential surface, a filter disposed along the inner circumferential surface of the basket, a screw disposed inside the basket and having screw blades on its outer circumferential surface, and a slurry pipe that supplies slurry and opens opposite the bottom of the basket, wherein the filter consists of a first filter disposed along the inner circumferential surface of the basket and a second metal filter disposed along the inner circumferential surface of the first filter, and the first filter is made of a filter with a mesh size that captures solid components that have passed through the second filter.

2. The centrifuge according to claim 1, characterized in that the first filter is made of fiber.

3. The centrifuge according to claim 1, characterized in that the first filter is made of a sintered wire mesh.

4. The centrifuge according to claim 1, 2, or 3, characterized in that the solid components captured by the first filter and filled into the pores of the second filter constitute a filtration layer.

5. The centrifugal separator according to claim 1, 2, or 3, characterized in that the inclination angle of the inner surface of the basket and the outer surface of the screw blades of the screw with respect to the central axis is set to 0 to 10°.

6. The centrifuge according to claim 1, 2, or 3, characterized in that the distance between the surface of the filter and the outer surface of the screw blades of the screw is set to 0.5 to 1 mm.

7. The difference in rotational speed between the basket and the screw is 1 to 10 mins. －１ The centrifuge according to claim 1, 2, or 3, characterized in that it is set to the following.

8. The centrifugal separator according to claim 1, 2, or 3, characterized in that the line width of the tip surface of the screw blades of the screw is set to 0.5 to 1 mm.

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