JP3884514B2 - Screw type decanter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screw type decanter, and more particularly to a structure of a stock solution supply pipe of a screw type decanter.
[0002]
[Prior art]
This type of screw-type decanter is suitable for continuous treatment of a stock slurry containing solid components and solid-liquid separation, and has been used in many fields such as the chemical industry, food industry, and wastewater treatment. Therefore, the conventional screw type decanter will be outlined. As shown in FIG. 2, the conventional screw type decanter is pivotally supported by a horizontal type cylindrical casing 1 and left and right main bearings 2, 2 arranged in accordance with the centers of both end faces of the casing 1. A cylinder 3 housed in the casing 1, a screw conveyor 4 which is inscribed in the cylinder 3 and rotates with a slight differential speed from the cylinder 3, and a hollow shape in which the screw conveyor 4 is wound spirally. A screw shaft 5 and a stock solution supply pipe 6 inserted coaxially in the screw shaft 5 are provided, and a stock solution slurry supplied from the stock solution supply pipe 6 is supplied to the cylinder 3 side. A liquid layer L is formed on the surface by centrifugal force, and solid components such as particulate substances in the raw slurry are centrifuged by a specific gravity difference from the liquid.
[0003]
As shown in FIG. 2, the cylinder 3 has a right end formed as a large diameter end portion 31 and a left end formed as a small diameter end portion 32. A plurality of light liquid ports 34 surrounding the shaft support portion 33 are formed in the large diameter end portion 31 at equal intervals in the circumferential direction, and the solid component is centrifuged in the cylinder 3 to obtain a supernatant liquid (hereinafter referred to as “light liquid”). "Liquid") is discharged from the light liquid port 34 as indicated by arrow C. Further, a plurality of heavy liquid ports 35 are formed at equal intervals in the circumferential direction at the left end portion of the cylinder 3, and a slurry having a large specific gravity (hereinafter referred to as “heavy liquid”) containing a solid component precipitate in the cylinder 3. ) Is scraped up by the screw conveyor 4 and discharged from the heavy liquid port 35 as indicated by an arrow D. The screw shaft 5 is supported by auxiliary bearings 7 and 7 in the cylinder 3 and connected to a speed reducer 9 through a spline shaft 8 at the left end. The screw shaft 5 is integrated with the screw conveyor 4 with a slight differential speed. Rotate in the same direction.
[0004]
The stock solution supply pipe 6 has an inlet end fixed by a holder 10 and an outlet end extended substantially to the middle of the screw shaft 5. The stock solution supply pipe 6 supplies the stock solution slurry that has flowed in from the direction of arrow A through a connection pipe (not shown) from the outlet end to the screw shaft 5. The stock slurry in the screw shaft 5 is ejected from the plurality of distribution holes 51 formed in the screw shaft 5 to the cylinder 3 side by the centrifugal force as shown by the arrow B, and the raw material slurry is light as described above in the cylinder 3. Centrifugation into liquid and heavy liquid.
[0005]
[Problems to be solved by the invention]
As outlined above, the conventional screw type decanter has the following problems. That is, when the rotational speed of the cylinder 3 is high and the centrifugal force is large, a strong centrifugal force acts on the raw slurry flowing out from the tip of the raw solution supply pipe 6, so that the raw slurry in the screw shaft 5 is divided into a plurality of distributions. Passing through the hole 51 at a high speed, it is scattered and collides violently with the liquid layer L formed on the inner peripheral surface of the cylinder 3, disturbing and mixing the liquid layer L, and reducing the centrifugal separation efficiency of the raw slurry. .
[0006]
In addition, when using a conventional screw type decanter as a classifier, it is necessary to reduce the rotational speed of the cylinder 3, but in this case, since the centrifugal force applied to the stock solution flowing out from the stock solution supply pipe 6 is small, The stock slurry that has flowed out of the stock solution supply pipe 6 stays in the screw shaft 5 and is not stably supplied continuously from the screw shaft 5 side to the screw conveyor 4 side through the distribution holes 51, so that stable classification is performed. I could not.
[0007]
The present invention has been made to solve the above-described problem, and the stock solution is transferred from the inside of the screw shaft to the liquid layer formed on the inner peripheral surface of the cylinder without disturbing the liquid layer formed on the inner peripheral surface of the cylinder. It can be supplied gently while forming a laminar flow, can be efficiently centrifuged by increasing the separation efficiency of the stock solution, and the stock solution is continuously and stably supplied from the inside of the screw shaft to the cylinder side even at a low rotational speed. It aims at providing the screw type decanter which can be performed.
[0008]
[Means for Solving the Problems]
A screw type decanter according to a first aspect of the present invention comprises a rotating cylinder having one end portion formed in a large diameter and the other end portion formed in a small diameter, and a shaft that rotates coaxially with the cylinder and with a slight differential speed. A hollow screw shaft having a screw conveyor wound around the surface, and a stock solution supply pipe coaxially inserted into the screw shaft, and the stock solution slurry supplied from the stock solution supply tube is centrifuged to In the screw type decanter that discharges the light liquid from the light liquid port formed in the large diameter end of the cylinder and discharges the heavy liquid from the heavy liquid port formed in the small diameter end of the cylinder, the stock solution supply A liquid supply nozzle having a closed end coaxially extending at the outlet end of the pipe, and supplying the stock solution into the liquid layer on the cylinder side through the peripheral wall of the screw shaft. the provided Together, linked via a fixing ring and the screw shaft and the solution feed pipe in the screw shaft, the screw shaft and the said stock solution supply pipe is characterized in that the rotate integrally.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the embodiment shown in FIG. FIG. 1 is a longitudinal sectional view of an essential part in the axial direction showing an embodiment of the screw type decanter of the present invention.
[0010]
As shown in FIG. 1, the screw type decanter of the present embodiment is basically configured according to the one shown in FIG. 2 except that the structure of the stock solution supply pipe and the screw shaft is different. Therefore, in the following, the same or corresponding parts as those of the screw type decanter shown in FIG.
[0011]
As shown in FIG. 1, the screw type decanter of this embodiment is rotated with a slight differential speed coaxially with the cylinder 3 having a right end portion formed in a large diameter and a left end portion formed in a small diameter. And a hollow screw shaft 5 around which a screw conveyor 4 is wound and an undiluted solution supply pipe 11 inserted coaxially into the screw shaft 5 and screwed by a reduction gear (see FIG. 2). The conveyor 4 and the screw shaft 5 rotate with a slight differential speed from the cylinder 3, and the stock slurry supplied into the cylinder 3 from the stock solution supply pipe 11 is separated into light and heavy liquids by centrifugal force. A light liquid having a small specific gravity is discharged from a light liquid port 34 drilled in the large-diameter end portion 31 and a specific gravity is large from a heavy liquid port drilled in the small-diameter end portion of the cylinder 3 (both see FIG. 2). Heavy liquid Out to.
[0012]
As shown in FIG. 1, the cylinder 3 includes a straight body portion 37 formed as a separation zone on the right side and a cone portion 36 formed as a frustoconical concentration zone on the left side of the straight body portion 37. The light liquid centrifuged in the liquid layer L overflows from the light liquid port 34 of the large-diameter end 31, and the precipitate is transferred to the concentration zone by the screw conveyor 4, where it is further concentrated and reduced in size as a heavy liquid. The liquid is discharged from the heavy liquid port at the end 32 (see FIG. 2).
[0013]
The screw conveyor 4 is formed in a spiral shape so as to be inscribed in the inner peripheral surface of the straight body portion 37, and is fixed to the screw shaft 5. A stock solution supply pipe 11 is coaxially inserted into the screw shaft 5, and the stock solution slurry is supplied into the straight barrel portion 37 through the stock solution supply pipe 11. The stock solution supply pipe 11 is fixed in the screw shaft 5 through a fixing ring 16 and rotates integrally with the screw shaft 5. The liquid supply cylinder 12 is connected to the distal end of the stock solution supply pipe 11 at the base end, and the distal end extends to the vicinity of the boundary between the straight body portion 37 and the cone portion 36. The liquid supply cylinder 12 is closed at the distal end, has a flange portion 12A at the proximal end, and is fixed to the screw shaft 5 via the flange portion 12A.
[0014]
The liquid supply cylinder 12 is provided with a plurality of liquid supply nozzles 13. That is, as shown in FIG. 1, two holes are formed in the liquid supply cylinder 12 in the longitudinal direction, and two holes are similarly formed at positions displaced from the two holes by, for example, 180 ° in the circumferential direction. Has been. Furthermore, one hole is formed in the liquid supply cylinder 12 at a position displaced by, for example, ± 90 ° in the circumferential direction at an intermediate position between the two holes. Further, the screw shaft 5 is formed with through holes 17 facing the holes of the liquid supply cylinder 12. A liquid supply nozzle 13 is fixed to each hole of the liquid supply cylinder 12 at the base end and extends outward in the radial direction, and a tip thereof penetrates each through hole 17 of the screw shaft 5. Moreover, each liquid supply nozzle 13 is formed to have a length that is immersed in the liquid layer L formed on the inner peripheral surface of the cylinder 3.
[0015]
Therefore, when the stock slurry is centrifuged by the screw type decanter, the tip of the liquid supply nozzle 13 is surely immersed in the liquid layer L in the cylinder 3, and the stock slurry is supplied into the liquid layer L in a laminar flow. The liquid layer L can be efficiently centrifuged without being disturbed as much as possible. The number of liquid supply nozzles 13 is set so that the flow rate is optimized in accordance with the supply amount of the raw liquid slurry, and the length of the liquid supply nozzle 13 is set so that the disturbance of the liquid layer L is reduced. To do.
[0016]
The stock solution supply pipe 11 has a seal member 14 mounted on the outer peripheral surface of the inlet end and is rotatably supported by a seal pressing member 15. There is a slight gap between the outer peripheral surface of the stock solution supply pipe 11 and the inner peripheral surface of the shaft support portion 33 of the cylinder 3 so that both are rotatable.
[0017]
Next, the operation will be described. When the speed reducer is started, the cylinder 3 rotates at a high speed and the screw conveyor 4 and the screw shaft 5 rotate at a slightly lower speed than the cylinder 3. At this time, when the stock solution slurry is continuously supplied to the stock solution supply pipe 11 from the direction of arrow A in FIG. 1, the stock solution slurry reaches the feed cylinder 12 from the stock solution supply pipe 11. Since the liquid supply cylinder 12 rotates integrally with the screw shaft 5, the stock solution slurry that has reached the liquid supply cylinder 12 passes through the liquid supply nozzles 13 at a plurality of locations by centrifugal force as shown by the arrow B in FIG. It flows out toward the inner peripheral surface of the cylinder 3. In the liquid supply nozzle 13, the stock solution slurry flows in a laminar flow and is guided to the inner peripheral surface of the cylinder 3.
[0018]
The undiluted slurry supplied to the cylinder 3 side forms a liquid layer L on its inner peripheral surface by the centrifugal force of the cylinder 3, and the solid component in the undiluted slurry is subjected to centrifugal force greater than that of the liquid due to the difference in specific gravity from the liquid. A heavy liquid layer is formed by precipitation in the layer L, and a light liquid layer having a reduced specific gravity at the surface layer portion of the liquid layer L is formed. Then, the continuous supply of the stock solution slurry gradually increases the depth of the liquid layer L in the cylinder 3, finally the liquid layer L reaches the liquid supply nozzle 13, and the tip of the liquid supply nozzle 13 enters the liquid layer L. Soaked.
[0019]
When the tip of the liquid supply nozzle 13 is immersed in the liquid layer L, the undiluted slurry flows into the liquid layer L in a laminar flow from the liquid supply nozzle 13, and the liquid layer L is gently disturbed without disturbing the liquid layer L as in the past. Supplied into layer L. Thus, in the case of this embodiment, since the undiluted slurry is gently poured into the liquid layer L in a laminar flow, there is little disturbance of the light liquid layer and the heavy liquid layer centrifuged in the liquid layer L, and the surroundings As a result, the clear liquid can overflow and be discharged from the light port 34 of the cylinder 3 as shown by the arrow C, and the specific gravity can be increased. Heavy liquid is transferred to the concentration zone by the screw conveyor 4 to be concentrated to a higher concentration and discharged from the heavy liquid port. However, in the case of a screw type decanter having a conventional structure, the raw slurry flows directly from the distribution hole to the clear light liquid layer of the liquid layer L, disturbing the light liquid layer and the heavy liquid layer over a wide range, and slurry. The slurry is transferred to the heavy liquid port side by the screw conveyor 4 and the suspended light liquid is transferred to the light liquid port side, so that the centrifugal separation effect is reduced.
[0020]
As described above, according to the present embodiment, the supply tube 12 having the tip closed coaxially with the outlet end of the stock solution supply pipe 11 is extended, and the peripheral wall of the screw shaft 5 is passed through the supply tube 12. Since the liquid supply nozzle 13 for guiding the raw liquid slurry to the cylinder 3 side is provided, the raw liquid slurry flowing out from the liquid supply nozzle 13 is poured into the liquid layer L in a laminar flow, and the disturbance of the liquid layer L is suppressed as much as possible. The centrifugal separation effect in the cylinder 3 can be enhanced.
[0021]
Further, according to the present embodiment, since the liquid supply nozzles 13 are dispersedly arranged over the entire circumference of the liquid supply cylinder 12, even if the rotational speed of the cylinder 3 is slow and the centrifugal force on the raw liquid slurry in the liquid supply cylinder 12 is small, The stock solution slurry does not stay in the feed tube 12 and flows out from each feed nozzle 13 stably and stably, and the stock solution slurry can be continuously and reliably separated into light and heavy liquids.
[0022]
The present invention is not limited to the above-described embodiment, and in particular, the number and length of the liquid supply nozzles can be appropriately set according to the supply flow rate of the stock solution slurry.
[0023]
【The invention's effect】
According to the first aspect of the present invention, laminar flow of the stock solution from the inside of the screw shaft to the liquid layer formed on the inner peripheral surface of the cylinder without disturbing the liquid layer formed on the inner peripheral surface of the cylinder . It is possible to perform the centrifugal separation efficiently by increasing the separation efficiency of the stock solution and forming the stock solution from the inside of the screw shaft to the cylinder side continuously and stably even at a low rotational speed. A screw-type decanter that can be provided can be provided.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a main part in an axial direction showing an embodiment of a screw type decanter of the present invention.
FIG. 2 is a longitudinal sectional view in the axial direction showing a conventional screw type decanter.
[Explanation of symbols]
3 Cylinder 4 Screw conveyor 5 Screw shaft 11 Stock solution supply pipe 12 Supply tube 13 Supply nozzle 31 Large diameter end 32 Small diameter end 34 Light liquid port 35 Heavy liquid port

Claims (1)

A rotating cylinder with one end formed in a large diameter and the other end formed in a small diameter, and a hollow screw shaft that rotates with a slight differential speed coaxially with the cylinder and has a screw conveyor wound around the outer peripheral surface And a stock liquid supply pipe coaxially inserted in the screw shaft, and a light liquid port formed in the large diameter end of the cylinder by centrifuging the stock solution slurry supplied from the stock solution supply pipe In the screw type decanter that discharges the light liquid from the cylinder and discharges the heavy liquid from the heavy liquid port formed in the small diameter end of the cylinder, the feed end is closed at the outlet end of the stock solution supply pipe. co on SL liquid supply nozzle for supplying a stock solution to the liquid supply tube through the wall of the screw shaft on the cylinder side of the liquid layer provided when extending the liquid cylinder, further, the screw shaft in the screw shaft And above Screw decanter a liquid supply pipe is connected via the fixing ring, the screw shaft and the said stock solution supply pipe, characterized in that the rotate integrally.

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