JP3945856B2 - Screw type decanter for liquid / solid-liquid separation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screw type decanter, and more particularly to a screw type decanter for liquid / solid-liquid separation.
[0002]
[Prior art]
Screw type decanters (hereinafter referred to as decanters) are suitable for continuous treatment of solids or sludge containing sludge, etc., and solid-liquid separation, so they are used in many fields such as chemical industry, food industry and sewage treatment. Has been. In the conventional decanter, as shown in the longitudinal sectional view of FIG. 5, a screw conveyor 2 is coaxially supported in a rotating bowl 3 having a truncated cone formed at one end, and the rotating bowl 3 and the screw conveyor 2 are supported. Is rotated at high speed in the same direction with a slight differential speed, so that the stock solution (slurry) supplied through the supply pipe 5 into the rotating bowl 3 is made solid using liquid centrifugal force. Separate into minute or sludge. That is, based on the specific gravity difference between the liquid and the solid, the separated liquid moved and separated radially inward is taken out from the separated liquid discharge port provided at the large-diameter end of the rotating bowl 3 through the annular weir plate 4, and The solid content or sludge moved and separated radially outward is taken out from a solid content outlet provided at the tip of the inclined portion of the rotating bowl.
[0003]
The decanter has the following problems. When the solid content in the stock solution is fine and the properties are soft, it is difficult to scrape the solid content by the screw conveyor 2 in the beach zone 6 due to the sliding phenomenon, and the solid content is not smoothly discharged. In such a case, the annular dam plate 4 was replaced and the liquid level of the inclined portion was raised.
[0004]
On the other hand, when the mixed slurry of light liquid, heavy liquid and solid content is processed to separate the respective components, the three-phase separation decanter of FIG. 4 is used. However, since it has the beach zone 10, when the solid content is fine and the property is soft, the same problem as the screw type decanter occurs and the solid content is not smoothly discharged. On the other hand, depending on the processed product, it may be necessary to separate heavy liquid / solid content-light liquid or light liquid / solid content-heavy liquid, which is cheaper than the decanter for three-phase separation. -A screw decanter for liquid separation was desired.
[0005]
[Problems to be solved by the invention]
The present invention has been made in order to solve the above-mentioned problems. A mixed slurry comprising a light liquid, a heavy liquid and a solid content is processed to obtain a heavy liquid / solid content-light liquid or a light liquid / solid content-heavy. An object of the present invention is to provide a screw-type decanter for liquid / solid content-liquid separation that can be separated into liquid, and is a screw-type decanter that is particularly suitable when the solid content is fine and the properties are soft.
[0006]
[Means for Solving the Problems]
The gist of the present invention for solving the above-mentioned problems is that claim 1 is connected to a truncated cone portion having a solid content discharge port at a small diameter end portion and a large diameter end side of the truncated cone portion, A rotating bowl composed of a cylindrical portion having a clarified liquid discharge port provided with an annular weir plate at the end, a screw conveyor provided coaxially with the rotating bowl and rotating with a slight differential speed, and the clarified liquid discharge port A screw type decanter comprising: a clarified liquid chamber provided adjacent to the clarified liquid chamber; a clarified liquid pumping means mounted with its tip immersed in the clarified liquid chamber; and a flow rate adjusting means connected to the discharge side of the clarified liquid pumped means. In order to control the position of the interface between the light liquid and the heavy liquid in the rotating bowl in the pipe connected to the discharge side of the clarified liquid pumping means, the pressure on the discharge side of the clarified liquid pumping means So that the And a flow control means is provided on the discharge side of the hydraulic pumping means, between at least one pitch of the screw blade which is located between the up cylinder end of the frusto-conical portion from the slurry dispensing port provided in the screw conveyor intermediate section A circular plate that keeps an appropriate distance from the inner wall of the rotating bowl and prevents light liquid from flowing to the frustoconical portion side is concentrically placed with the screw blades concentrically sandwiched between the screw conveyor shafts. It was set, light liquid, processing the mixed slurry of heavy liquid and solid, heavy liquid-to the solids discharge port heavy liquid and solid matter, characterized by having the structure of separating the light liquid from the clarified liquid discharge port It is a screw type decanter for solid-light liquid separation .
[0007]
Further, the second aspect of the present invention is a clarified liquid drainage comprising a truncated cone portion having a solid content discharge port at a small diameter end portion and a large diameter end side of the truncated cone portion and an annular dam plate provided at the other end. A rotating bowl comprising a cylindrical portion having an outlet, a screw conveyor provided coaxially with the rotating bowl and rotating with a slight differential speed, a clarification liquid chamber provided adjacent to the clarification liquid discharge port, and the clarification liquid In a screw type decanter comprising a clarified liquid pumping means mounted with its tip immersed in the liquid chamber and a flow rate adjusting means connected to the discharge side of the clarified liquid pumping means, connected to the discharge side of the clarified liquid pumping means In order to control the position of the interface between the light liquid and the heavy liquid in the rotary bowl, the clarified liquid is adjusted so that the pressure on the discharge side of the clarified liquid pumping means is within a predetermined range. Flow rate adjusting means on the discharge side of the pumping means Provided, to hold the inner and appropriate spacing of the rotary bowl, the cylindrical portion end the light liquid from flowing clarified liquid chamber side a circular plate suppresses from the slurry dispensing port provided in the screw conveyor intermediate section Is installed on the screw conveyor shaft between the clarified liquid discharge port and the mixed slurry consisting of light liquid, heavy liquid and solid content, and the light liquid, solid content and clarified liquid discharged from the solid content discharge port. A screw type decanter for separating a light liquid / solid content-heavy liquid, characterized in that it comprises a structure for separating a heavy liquid from an outlet.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view of a screw-type decanter for liquid / solid-liquid separation according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of a screw / decane for liquid / solid-liquid separation according to another embodiment of the present invention. FIG. 3 is a perspective view of an embodiment of a partition plate which is a main part. In addition, the same number was attached | subjected about the common member.
[0010]
The configuration of the screw type decanter of the present invention will be described with reference to FIG. Reference numeral 12 denotes a partition plate which is a main part of the present invention, and is a circular or rectangular plate, and is erected on the shaft of the screw conveyor 15. Reference numeral 13 denotes a rotating bowl, which is a rotating body composed of a truncated cone portion and a cylindrical portion. Reference numeral 14 denotes a slurry distribution port, which is provided in the middle of the hollow body of the screw conveyor 15 so as to open outward in the radial direction. A screw conveyor 15 has screw blades and is provided coaxially with the rotating bowl 13 and rotates with a slight differential speed. Reference numeral 16 denotes a vertical separation plate, which is composed of a large number of vertically long flat plates protruding at an inclined angle with respect to the radial direction at equal intervals on the outer periphery of the shaft of the screw conveyor 15. The longitudinal separation plate 16 is wound between the outer end edge of the screw conveyor by the spiral surface of the screw conveyor and between the slurry distribution port 14 and the end of the cylindrical portion where the clarified liquid discharge port 17 is located.
[0011]
Reference numeral 17 denotes a clarified liquid discharge port, which is formed at the end of the cylindrical portion of the rotating bowl 13 opposite to the truncated cone portion. Reference numeral 18 denotes an annular weir plate provided at the clarified liquid discharge port 17. By using a large annular dam plate 18 to reduce the opening area of the clarified liquid discharge port 17, the residence time of the liquid in the rotating bowl can be increased. Reference numeral 19 denotes a clarification liquid chamber provided adjacent to the clarification liquid discharge port 17. A liquid supply pipe 20 is composed of a flange and a circular pipe, and is provided so that the end of the circular pipe on the side opposite to the flange side comes to a position where the raw solution mixed slurry can be supplied to the middle part of the screw conveyor hollow cylinder. Reference numeral 21 denotes a centripetal impeller that is a means for pumping the clarified liquid. The centripetal impeller is disk-shaped and is attached to the clarified liquid chamber 19 and its tip opening is immersed in the light liquid. Reference numeral 22 denotes a solid content outlet, which is provided to open in the radially outward direction at the small diameter end of the frusto-conical portion of the rotary bowl 13. 23 is a pressure gauge and 24 is a flow rate adjusting means comprising a flow rate detector and a control valve. Reference numeral 25 denotes an interface between a heavy liquid and a light liquid. The operation of the screw type decanter having the above configuration will be described below.
[0012]
In FIG. 1, the mixed slurry of light liquid, heavy liquid, and solid content is supplied from the liquid supply pipe 20 to the separation zone of the cylindrical portion of the rotating bowl 13 through the slurry distribution port 14. The slurry subjected to the centrifugal force is separated into three phases of solid, heavy liquid, and light liquid in the order of components having a higher specific gravity to form an interface 25 between the heavy liquid and the light liquid. On the way, the solid content of the fine particles is captured by the longitudinal separation plate 16 and collected near the inner wall of the rotating bowl 13. Then, the separated solid content is moved to the solid content outlet 22 side together with the heavy liquid by the rotation of the screw conveyor 15, and is discharged to the outside. At this time, the partition plate 12 erected on the screw conveyor from the slurry distribution port 14 in the rotating bowl 13 to the end of the truncated cone portion becomes a resistance so that the light liquid does not go to the solid content discharge port 22 side. Since it functions as a barrier, only heavy liquid and solid content can be discharged.
[0013]
On the other hand, the light liquid flows through the clarified liquid discharge port 17 and overflows the annular dam plate 18 and stays in the clarified liquid chamber 19. Further, the light liquid is discharged to the outside through a flow rate adjusting means 24 connected to the light liquid discharge side by a centripetal impeller 21 which is mounted in the clarified liquid chamber 19 and whose tip opening is immersed in the light liquid. Is done.
[0014]
FIG. 2 is an invention of another embodiment, and a screw type decanter in which a partition plate 26 is erected on a screw conveyor 15 shaft between a slurry distribution port 14 and a clarified liquid discharge port 17 drilled at the end of the cylindrical portion. It is. The process of separating the mixed slurry in the rotating bowl 13 is the same as in the case of FIG. 1, but the light liquid / solid content can be separated on the solid content outlet 22 side and the heavy liquid can be separated on the clarified liquid chamber 19 side. The partition plate 26 acts as a barrier to prevent light liquid from going to the clarified liquid chamber 19 side, so that the light liquid / solid content can be suitably discharged to the solid content discharge port 22 side.
[0015]
Next, the position control method of the interface between the light liquid and the heavy liquid in the rotating bowl of the screw type decanter according to the present invention will be described in the case of FIG. In the screw type decanter of the present invention, during operation, the minimum pressure value on the discharge side of the centripetal impeller 21 when the liquid flows out from the solid content discharge port 22 based on a constant flow rate, centrifugal effect, and differential speed of the screw conveyor is set in advance. By calculating the control valve of the flow rate adjusting means 24 in a predetermined adjustment region so that the pressure value becomes higher than the reference pressure value during operation with this pressure value as a reference pressure value, the inside of the rotary bowl 13 is obtained. You can drive a decanter without a beach zone. Therefore, even if the solid content is fine and the property is soft, a predetermined amount can be discharged to the outside without difficulty due to the synergistic effect of the transfer force of the screw conveyor and the hydraulic pressure by increasing the liquid level.
[0016]
Further, when the pressure on the discharge side of the centripetal impeller 21 is increased by narrowing the control valve of the flow rate adjusting means 24, the light liquid leaks to the solid content discharge port 22 side. The maximum pressure value on the discharge side of the centripetal impeller 21 at this time is obtained with the pressure gauge 23, and the control valve of the flow rate adjusting means 24 is adjusted in a predetermined adjustment region so as to be equal to or less than the maximum pressure value. Leakage to the solid content outlet 22 can be prevented. As described above, the control valve of the flow rate adjusting means 24 is adjusted in a predetermined adjustment region so that the pressure value during operation on the discharge side of the centripetal impeller 21 is between the minimum pressure value and the maximum pressure value. Thus, the interface 25 between the light liquid and the heavy liquid can be maintained at a suitable position.
[0017]
Next, a method for controlling the position of the interface 27 between the light liquid and the heavy liquid in the case of FIG. 2 will be described. The method for obtaining the minimum pressure value is the same as in FIG. Further, the maximum pressure value is the same as in FIG. 1. When the pressure on the discharge side of the centripetal impeller 21 is increased by narrowing the control valve of the flow rate adjusting means 24, heavy liquid leaks to the solid content discharge port 22 side. The centripetal impeller 21 at this time can be obtained from the indicated value of the pressure gauge 23 on the discharge side. Here, similarly to the above, the control valve of the flow rate adjusting means 24 is adjusted in a predetermined adjustment region so that the pressure value during operation on the discharge side of the centripetal impeller 21 is between the minimum pressure value and the maximum pressure value. If it does so, the interface 27 of a light liquid and a heavy liquid can be maintained in a suitable position.
[0018]
FIG. 3 shows an example of a partition plate (two-dot chain line) used in the present invention. B) is a circular plate, and b) is a rectangular plate. A) is erected coaxially with the axis of the screw conveyor across the spiral surface of the screw blades, and b) is erected between the screw blades. In addition, when using a rectangular plate, the two plates (fixed on the inner side in the radial direction and free on the outer side in the radial direction) are moved up and down through the idiot hole so that the distance between the inner wall of the rotating bowl and the partition plate can be adjusted freely. You can also make it slideable.
[0019]
Although the embodiment of the invention of FIGS. 1 and 2 has been described with an example in which the longitudinal separator is disposed in the rotating bowl, the longitudinal separator may not be provided if the solid content is not fine particles. .
[0020]
【The invention's effect】
Using the above screw type decanter of the present invention, if the mixed slurry of light liquid, heavy liquid and solids is processed,
B) Separation can be easily made into heavy liquid / solid content-light liquid or light liquid / solid content-heavy liquid by simply changing the left / right setting position of the partition plate to the screw conveyor shaft in the cylindrical portion of the rotating bowl.
B) Since skimming is not discharged at the interface between the light and heavy liquids, the solids in the emulsion at the interface between the light and heavy liquids are more solid than the decanter for three-phase separation because the solids in the emulsion at the interface can be separated longer. The fraction recovery rate is high.
C) In the case of a three-phase separation decanter, an equipment for mixing the liquid once separated and the solid content is required. However, since the desired separation can be performed only with the main body, the equipment cost is low.
D) Clear liquid pumping means The liquid level in the rotating bowl is raised using the flow rate adjusting means on the discharge side, and it operates without a beach zone, so the synergistic effect of the solid content transfer force of the screw conveyor and the hydraulic pressure Therefore, a predetermined amount can be discharged without difficulty even with a solid content of fine particles and soft properties.
E) When a longitudinal separation plate is provided, it is possible to separate and discharge even a mixed slurry containing fine solid particles having a soft property.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a screw type decanter according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of a screw type decanter according to another embodiment. FIG. FIG. 4 is a perspective view of a screw type decanter for three-phase separation. FIG. 5 is a vertical sectional view of a conventional screw type decanter.
12 Bulkhead Plate 13 Rotating Bowl 14 Slurry Distributing Port 15 Screw Conveyor 16 Longitudinal Separating Plate 17 Clarified Liquid Discharge Port 18 Annular Weir Plate 19 Clarified Liquid Chamber 20 Liquid Supply Pipe 21 Centripetal Impeller (Clarified Liquid Pumping Means)
22 Solid content outlet 23 Pressure gauge 24 Flow rate adjusting means 25 Interface between light liquid and heavy liquid 26 Partition plate 27 Interface between light liquid and heavy liquid

Claims (2)

A truncated cone portion having a solid content discharge port at the small diameter end portion, and a cylindrical portion having a clarified liquid discharge port connected to the large diameter end side of the truncated cone portion and provided with an annular weir plate at the other end A rotating bowl, a screw conveyor provided coaxially with the rotating bowl and rotating with a slight differential speed, a clarified liquid chamber provided adjacent to the clarified liquid discharge port, and a tip immersed in the clarified liquid chamber In the screw type decanter comprising the clarified liquid pumping means and the flow rate adjusting means connected to the discharge side of the clarified liquid pumping means, pressure is applied to the pipe line connected to the discharge side of the clarified liquid pumping means. In order to control the position of the interface between the light liquid and the heavy liquid in the rotary bowl, the discharge side of the clarified liquid pumping means is adjusted so that the pressure on the discharge side of the clarified liquid pumping means is within a predetermined range. provided a flow control means, said scan From the slurry distribution orifice provided in Liu conveyor intermediate section between at least one pitch of the screw blade which is located between the up cylinder end of the frusto-conical portion, to hold the inner and appropriate spacing of the rotary bowl, light A circular plate that suppresses the flow of liquid to the frustoconical portion side is erected coaxially with the screw blades concentrically on the axis of the screw conveyor, and mixed slurry consisting of light liquid, heavy liquid and solid content A screw type decanter for separating heavy liquid / solid content-light liquid , which is treated and separated from a solid liquid discharge port from a heavy liquid and a solid content and from a clarified liquid discharge port. It consists of a truncated cone portion having a solid content discharge port at the small diameter end portion, and a cylindrical portion having a clarified liquid discharge port connected to the large diameter end side of the truncated cone portion and provided with an annular weir plate at the other end. A rotating bowl, a screw conveyor provided coaxially with the rotating bowl and rotating with a slight differential speed, a clarified liquid chamber provided adjacent to the clarified liquid discharge port, and a tip immersed in the clarified liquid chamber A screw type decanter comprising a clarified liquid pumping means and a flow rate adjusting means connected to the discharge side of the clarified liquid pumping means, and a pressure gauge connected to a pipe line connected to the discharge side of the clarified liquid pumping means In order to control the position of the interface between the light liquid and the heavy liquid in the rotating bowl, the flow rate to the discharge side of the clarified liquid pumping means is adjusted so that the pressure on the discharge side of the clarified liquid pumping means is within a predetermined range. provided adjusting means, the rotation Holding the inner and appropriate intervals ur, is bored a circular plate restrain the light liquid flows into the clear liquid chamber side in the cylinder end from the slurry dispensing port provided in the screw conveyor intermediate section Stands on the screw conveyor shaft up to the clarified liquid discharge port to process the mixed slurry consisting of light liquid, heavy liquid and solid content, and to remove the light liquid and solid content from the solid content discharge port and heavy liquid from the clarified liquid discharge port. A screw type decanter for light / solid / heavy liquid separation , characterized in that it comprises a separating structure.

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