JPS58189056A - Screen for centrifugal separator - Google Patents

Abstract

PURPOSE:To obtain a screen having long life and high economical efficiency, by providing plural slits to each circumferential segmental pieces constituting a cylindrical screen in such a manner that said slits are formed in almost same parallel relation from the inner surface side of a cylinder to the outer surface side thereof. CONSTITUTION:Plural slits 3 arranged to the circumferential segmental pieces 2 and the adjusting spacer segmental pieces 2' of a screen 1 in parallel with the axial direction of a cylinder are formed in almost parallel relation from the inner surface side of the thickness of the cylinder to the outer surface side thereof. As the result, even if contact friction due to a hard particle such as an ammonium sulfate particle is generated to the inner peripheral surface of the screen 1 to advance friction, a slit width is not changed from the inner surface side to the outer surface side and, therefor, the screen 1 can be used without replacing the same until the plate material thereof becomes thin by abrasion. As the result, the screen capable of accomplishing sufficient function over a long period of time and having high economical efficiency is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a screen for a centrifuge.

A basket centrifuge has a cylindrical screen installed inside the basket to centrifugally separate solids and liquids. % (1) In the case of a screen used in a cylindrical extrusion type continuous centrifuge, a screen with a large number of narrow slits arranged in the axial direction of the cylinder is used. However, the slit width of this screen Although it differs depending on the type of crystal1, if a fine gap of 05W1 or less is required, it has been conventionally compared to the opening width of the inner surface of the cylinder, with emphasis on the problem of cutting the slit part, prevention of blockage, and dehydration effect. The width of the opening on the outer surface was wide at an angle of about 6 to 12 degrees.When centrifuging a crystal slurry solution using a screen with such a configuration,
The outflow speed of the separated liquid increases, and the outflow speed reaches the maximum at the entrance of the slit on the inner surface of the cylinder, which has a relatively small opening width. Therefore, when a slurry solution with a relatively wide particle size distribution such as ammonium sulfate is centrifuged continuously, the crystal particles are extremely hard even if they are minute, so the entrance of the slit inside the cylinder has a high flow rate. The part wears out rapidly due to contact friction, and the slit rj] is gradually enlarged,
As a result, the crystals begin to flow out into the liquid. For this reason, the slits were unable to perform the separation function, resulting in an economically uneconomical screen with an extremely short lifespan.

The inventors of the present invention conducted research aimed at eliminating these drawbacks of conventional screens, and found that when the slits were formed in almost the same parallel portion from the inner surface to the outer surface of the cylinder, the slits Since the outflow speed of the separated liquid passing through the slit remains constant, the degree of wear at the entrance of the slit is significantly reduced, and even if the wear progresses, the rate of crystal outflow into the liquid remains almost unchanged from the initial stage.
It has been found that it is possible to obtain a highly economical screen that can perform good centrifugation work over a long period of time.

The structure and operation of the present invention will be explained based on embodiments of the drawings.

(1) shows a cylindrical screen for centrifugal separation, which screen is usually constituted by a plurality of circumferential sections (2) and adjustment spacer sections (i) with the same radius of curvature. , the adjustment spacer piece (2) is used if necessary. (3) is a large number of slits arranged parallel to the axial direction of the cylindrical body in the circumferential segment (2) and the adjustment spacer segment (21) of this screen (1), and the opening width of this slit is 0.5 Below the order, preferably 01 to 0
．． 3 Make it about a grade. And this slit (3
1 is formed in substantially the same parallel portion from the inner surface side to the outer surface side of the cylindrical body. The wall thickness of the circumferential segment (2) and the adjustment spacer segment (2) constituting this cylindrical body is preferably 1 to 5 days, and as the thickness increases, pressure loss increases.

The smaller the thickness, the faster the wear and tear. The opening width of the slit (3) may be slightly larger on the outer surface side than on the inner surface side. Further, the distance between adjacent slits (3) is preferably 5 to 20 times the distance between the slits. (4) are reinforcing ribs provided approximately parallel to each other at appropriate intervals in the radial direction of the outer circumferential surface of the circumferential segment (2), and integrate the plurality of slits. These reinforcing ribs (4) are provided at intervals of 2 to 5 times the width in the axial direction, and openings (3°) 1, which are extensions of the slits, are also provided on a part of the inner surface of the reinforcing ribs. It is preferable.

Therefore, when manufacturing the circumferential pieces (2), first, a flat plate (for example, a stainless steel plate) of an arbitrary length is curved so as to have the desired radius of curvature of the cylindrical screen, and then it is curved in parallel at predetermined intervals. By cutting the slit using an arbitrary method, the opening widths on the inner surface and the outer surface are formed into substantially the same parallel portions.

FIG. 5 is a schematic diagram showing a state in which the screen (1) of the present invention described above is attached to a cylindrical extrusion type continuous centrifugal separator. (5) is a cylindrical first stage basket whose shaft at one end is rotated by a motor (not shown) and at the same time reciprocates at a constant stroke, and a crystal extrusion segment (6) is provided at the tip of its outer periphery. , and an extrusion plate (7) is installed on the inside thereof. (8) is a cylindrical second-stage basket whose shaft portion at one end is rotated by a motor (not shown). (9) is a crystal slurry supply pipe, and (10) is a slurry distributor.

The embodiment shown in FIG. 5 is a two-stage screen type centrifuge in which the screen (1) of the present invention is installed inside a first-stage basket (5) and a second-stage basket (8), respectively. be. The crystal slurry that is now continuously supplied from the crystal slurry supply pipe (9) is first distributed from the slurry distributor (101) to the screen (1a) of the first stage basket (5), and the liquid is distributed outside the screen (1). The crystal cake ■ is discharged from the side and falls onto the screen (1b) of the second stage basket (5), and is separated on the inner surface of the screen (1a) (1b). By reciprocating, the crystal extrusion segment (6) and the extrusion plate (7) can continuously discharge the crystal to the outside in a reciprocating stroke.

The screen of the present invention is most suitable for the above-mentioned cylindrical extrusion type continuous centrifugal separator, but it can also be used, for example, for batch processing of crystal slurry and scraping off the crystal cake on the screen with a reciprocating scraping blade. Of course, it can also be used in a basket type centrifuge.

In this way, the present invention provides a plurality of slits (3) in each of the circumferential segments (2) constituting a cylindrical screen, with substantially the same parallel portions extending from the inner surface to the outer surface of the cylinder. Because of this characteristic, the slit width does not change from the inner surface to the outer surface even if wear progresses due to contact friction caused by hard particles such as ammonium sulfate on the inner peripheral surface of the screen, so it is recommended to replace it. It can be used until the entire screen plate material wears out and becomes thin, making it a highly economical screen that can fully perform its functions for a long period of time, and its effects are extremely large.

Examples of the present invention are as follows. The comparative data shown here is based on the amount of ammonium sulfate crystals produced by continuously feeding an ammonium sulfate slurry aqueous solution (slurry concentration 4° VO 1% or more) to a two-stage basket cylindrical extrusion type continuous centrifuge shown in Figure 5. It was operated at a rate of 4000 kf/H.

(1) Conventional screen (first stage basket side - diameter 347+a+1.7'/x length 8Q rm x 2 rows, wall thickness 3 ran).

2nd stage basket side - diameter 410mm% x length 8゜■
2 rows, wall thickness 3 rrm, slit width for both 1st and 2nd stage is 02mm on the inner side and 1mm or more on the outer side (spreading angle 9°)
When the slurry is processed by drilling with 3 adjacent pitches), wear due to ammonium sulfate crystals rapidly progresses from the slit edges on the inner surface of the Niscreen, and after 2 months, the concentration of slurry flowing out to the mother liquor side is 1 Ovol 96 As a result, the entire screen had to be completely replaced.

(2) Processed with the screen of the present invention (the slit width is 0.2311111 on the inner side for both the first and second stage basket sides, and is the same as the conventional screen except that it is almost the same as the 0.25 mm on the outer side) Case: Although wear is observed on the inner slit edges after 5 months, the concentration of slurry flowing to the mother liquor side and the amount of ammonium sulfate crystals produced are almost the same as at the start of work, and the screen itself is even worse. It was confirmed that it can be used to perform the same function for a long period of time.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a front view of the entire screen, FIG. 2 is a front view of the main parts of the same, and FIG.
The figure is a plan view of the same as above, FIG. 4 is an enlarged sectional view taken along line A--A of the above, and FIG. 5 is a schematic side sectional view of the centrifugal separator in operation. Patent applicant: Kushichi Iron Works Co., Ltd.

Claims (1)

[Claims] 1. In a cylindrical screen with a large number of slits, a large number of slits are provided parallel to each other in the axial direction of the cylinder, and the slit widths are approximately the same in parallel from the inner surface to the outer surface of the cylinder. A screen for a centrifuge, characterized in that the screen is formed in a portion. 2 The slit width is 0.5a or less, preferably 01~
The screen for a centrifuge according to claim 1, which has a diameter of 0.03 mm. 3. The screen for a centrifuge according to claim 1, wherein the cylindrical body is constituted by a plurality of circumferential pieces having the same radius of curvature and adjustment spacer pieces. 4. The screen for centrifugal separation according to claim 1, wherein the centrifugal separator is a cylindrical extrusion type continuous centrifugal separator.