JPH0520445Y2 - - Google Patents

Description

[Detailed description of the invention] Field of industrial application This invention relates to a screw decanter type centrifugal concentrator, and in particular to a screw decanter type centrifugal concentrator which has a cylindrical drum which rotates in one direction and a screw conveyor inside the drum which is coaxial with the drum and rotates in the same direction with a rotation difference, in which solids are separated and settled by centrifugal force from a suspension supplied into the drum through a hollow support shaft, and the concentrated liquid which is accumulated on one side of the drum by the screw conveyor is discharged from the hollow support shaft separately from the separated liquid from which the solids have been separated.

Prior Art Conventional screw decanter type centrifugal concentrators generally have a nozzle installed on one side wall of the drum from which the concentrated liquid accumulated on the screw conveyor is discharged, and the nozzle protrudes around the side wall. During operation, the amount of discharge from the nozzle cannot be adjusted in response to fluctuations in the amount of suspension supplied or the solid content concentration, etc., as it rotates with the drum.
In addition, it has various disadvantages such as a large loss of power due to air resistance and a large loss of kinetic energy of the discharged liquid.

In order to deal with this problem, a screw decanter type centrifugal concentrator of the above-mentioned type has been developed in recent years, in which the separated liquid and concentrated liquid are discharged through the inside and outside of a support shaft having a double tube structure, respectively. Tokukai Akira
An example is that shown in No. 59-136152. As shown in Fig. 5, in this device, a suspension is supplied from one hollow shaft a, introduced into a drum d through a guide duct c attached to a screw conveyor b, and directed toward the other end of the drum. While the drum is moving, the solid content is sedimented and separated by the centrifugal action caused by the rotation, and two layers, a concentrated liquid layer and a separated liquid layer, are formed at the other end of the drum. Then, they are discharged to the outside of the machine through a skimmer pipe e and a guide duct f, which are respectively attached to the screw conveyor b, through the inside and outside of a hollow shaft g having a double pipe structure. According to this device, the kinetic energy of the discharged liquid is recovered as driving energy of the device, and is discharged from the axis center or its vicinity with almost no kinetic energy. There are no protrusions or openings on the wall, so power consumption is reduced due to low air resistance. Also, by providing a regulating valve h at the outlet of the hollow support shaft, the discharge amount can be adjusted to the suspension supply amount or the suspension amount even during operation. It has the advantage that it can be adjusted according to fluctuations in the solid content concentration, but on the other hand, if the concentrated liquid becomes highly viscous depending on the liquid properties, there is a risk that the skimmer tube e will be clogged.

Problems that the invention aims to solve The technical problems of this invention are to solve the problem of clogging in the above-mentioned centrifugal concentrator where discharge is performed from the shaft center, and to make it possible to discharge even highly viscous concentrated liquid. shall be.

Solution to the problem In this project, the drum and screw conveyor form a funnel-shaped discharge path toward the axis, and the difference in rotational speed between the drum and the screw conveyor gives fluidity to the concentrated liquid in the discharge path. This is an attempt to solve the above problem.

In other words, the present invention has a cylindrical drum that rotates in one direction, and a screw conveyor that is coaxial with the drum within the drum and rotates in the same direction with a rotational difference, and supplies the screws into the rotating drum. The solid content is separated and sedimented from the suspension by centrifugal force,
In a screw decanter type centrifugal concentrator, this liquid is accumulated on one side of the drum by a screw conveyor and discharged from a hollow support shaft separately from the separated liquid. It is characterized in that a cone portion is provided protruding from each side, and a funnel-shaped discharge path toward the axis is formed between the two, and the concentrated liquid is discharged from the discharge path.

Depending on the viscosity of the concentrated liquid, for example, in the case of low viscosity, the cone protruding from one side of the screw conveyor is not provided with a screw blade, and is used only by the supply pressure of the suspension. If the liquid has poor fluidity, a screw blade is installed, and in addition to the supply pressure of the suspension, the conveying force of the screw conveyor is used to carry the concentrated liquid out of the machine.

Embodiment Figure 1 shows an example suitable for use in concentrates with relatively high viscosity.The drum 1 is rotatable horizontally by a bearing 3 on a hollow shaft 2 protruding from side to side. A hollow shaft 2 that is pivotally supported and has one side as the discharge side
A pulley 4 is attached to a hollow shaft 2 on the supply side, which is formed into a cone shape toward the center and connected to a pump (not shown), and is driven by a belt from a drive source (not shown). A screw conveyor 8 having screw blades 7 on the outer periphery of a cylindrical body 6 is also built into the drum 1 coaxially with the drum 1, and a hollow shaft 9 protruding toward the supply side protrudes through the hollow shaft 2. The projecting end is pivotally supported by a bearing 11. A pulley 12 is also fixed to the hollow shaft 9 on the supply side, and is driven by a belt from the drive source so as to rotate in the same direction as the drum 1 with a rotational difference.

The shell 6 of the screw conveyor 8 further forms a double pipe structure with the hollow shaft 2 on the discharge side.
A pipe 14 that penetrates through the drum and is pivotally supported by a bearing 10 at its protruding end is provided to protrude laterally, and a cone portion 6' having an appropriate clearance with the cone portion 1' on one side of the drum is provided so that a shaft can be inserted between the two. A funnel-shaped discharge passage 13 toward the center is formed, and the screw blades 7 are provided up to the cone portion 6', and a plurality of radial passages 15 are provided on the left and right side walls, respectively, through which the hollow shaft 9 or pipe 14 passes. There is.

On the discharge side, a cone-shaped pipe 16 and a flow rate regulating valve 17 are provided at the outlet of the hollow shaft 2 and the outlet of the pipe 14 protruding from the shaft 2, respectively.
The concentration of the concentrated liquid can be adjusted by adjusting the discharge ratio of the concentrated liquid and the separated liquid. 19 is a cover surrounding the drum 1.

Although not shown, there are mechanical seals, oil seals, etc. between the hollow shaft 2 and the hollow shaft 9, between the hollow shaft 2 on the discharge side and the discharge reservoir 21, between the pipe 14 and the discharge reservoir 22, etc. It is thus sealed to prevent suspension and discharged liquid from leaking outside.

This device is constructed as described above, and the suspension supplied under pressure by a pump (not shown) connected to the hollow shaft 9 on the supply side enters the drum 1 through the flow path 15, and is centrifuged by the rotation of the drum. Solids are separated and settled by force. The concentrated liquid containing solids that settles on the inner circumferential wall of the drum is scraped toward the discharge side by the screw conveyor 8, which rotates in the same direction with a rotational difference from the drum, and is scraped near the boundary between the cylindrical part and the cone part. Two layers are formed: a thickened sludge layer and a separated liquid layer.
The concentrated sludge is then similarly scraped through the funnel-shaped discharge passage 13 toward the axis, and then discharged through the space between the hollow shaft 2 and the pipe 14, the valve 16, and the discharge reservoir 21. On the other hand, the separated liquid is discharged from the flow path 15 on the discharge side, through the pipe 14 and the flow rate adjustment valve 17, and through the discharge reservoir 22. While the separated liquid and concentrated liquid pass through the flow path 15 and the discharge path 13 on the discharge side, their kinetic energy is used as part of the driving power for the screw conveyor and the drum.

When adjusting the concentration concentration of the concentrated liquid, the discharge amount is adjusted by the flow rate adjustment valve 17. That is, since the sum of the discharge amounts of the separated liquid and the concentrated liquid is equal to the supply amount of the suspension, increasing the discharge amount of the separated liquid increases the concentrated concentration, and conversely, decreasing the discharge amount decreases the concentrated concentration. Therefore, the concentrate concentration can be maintained at a predetermined value by changing the discharge ratio depending on the concentration of the suspension.

According to this embodiment, the concentrated liquid is scraped through the discharge path 13 by the supply pressure of the suspension liquid and the screw blades, but while passing through the discharge path, the difference in rotational speed between the drum and the screw conveyor causes A shearing force is applied and fluidization is maintained up to the discharge reservoir 21. Therefore, even if the concentrated liquid becomes highly viscous, there is no risk of clogging.

The embodiment shown in FIG. 2 is the same as the embodiment shown in FIG. 1, but the screw blade provided in the cone portion 6' is omitted, and the concentrated liquid is discharged only by the supply pressure of the suspension. This is what I did. This embodiment is used when the viscosity of the concentrate is relatively low, and this method is extremely effective since low-viscosity concentrates tend to slip on the screw conveyor. Note that the angle of the cone part can be set larger than that of a normal centrifugal separator because the concentrated liquid is discharged using the supply pressure of the suspension liquid.

The embodiment shown in FIG. 3 is different from the embodiment shown in FIGS. 1 and 2 in that a disc spring 20 is provided behind the valve 16 so that the opening degree can be adjusted according to the pressure of the concentrated liquid. That is, when the pressure of the concentrated liquid increases, the degree of opening increases, making it possible to prevent blockage due to the concentrated liquid.

In the embodiment shown in FIG. 4, in the embodiment shown in FIGS. 1 and 2, the valve is a flow rate adjustment valve 23 similar to the flow rate adjustment valve 17, and is provided at the outlet of the discharge reservoir 21. According to this embodiment, the amount of concentrated liquid discharged can be adjusted, and it is also easy to disassemble and clean when clogged.

Effects of the invention As described above, the screw decanter centrifugal concentrator of the present invention has a cone protruding from each side of the drum and the screw conveyor to form a funnel-shaped discharge path toward the axis between them. However, the concentrated liquid is discharged from the discharge path, and because the discharged liquid is discharged from the shaft center or near it, the kinetic energy of the discharged liquid is extremely low compared to conventional machines that are discharged from the drum side wall. The kinetic energy of the discharged liquid is recovered as drive energy for the device, reducing power consumption. Fluidization is maintained in the discharge path as shearing force is applied due to the difference in rotational speed between the drum and the screw conveyor. It has the advantage of being less likely to cause blockage.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a screw decanter type centrifugal concentrator which is an embodiment of the present invention, Fig. 2 is a schematic diagram showing a part of another embodiment, and Fig. 3 is a part of still another embodiment. Schematic diagram, FIG. 4 is a partial schematic diagram of another embodiment,
FIG. 5 is a schematic diagram of a conventional example. 1...Drum, 2...Hollow shaft, 4...Pulley,
6'... Cone part, 7... Screw blade, 8...
...Screw conveyor, 9...Hollow shaft, 1
2...Pulley, 13...Outflow path, 14...Pipe, 15...Flow path, 16...Valve, 17, 23
...Flow rate adjustment valve, 19...Disc spring, 21, 22...
...Drainage reservoir.

Claims (1)

[Scope of utility model registration request] It has a cylindrical drum that rotates in one direction, and a screw conveyor that is coaxial with the drum within the drum and rotates in the same direction with a rotational difference, and the suspension is supplied to the rotating drum. A screw system that uses centrifugal force to separate and settle solids from a liquid, collects them on one side of a drum using a screw conveyor, and discharges them from a hollow support shaft separately from the separated liquid. In a decanter-type centrifugal concentrator, a cone is provided on each side of the drum and screw conveyor to form a funnel-shaped discharge path toward the axis between them, and the concentrated liquid is discharged from the discharge path. A screw decanter type centrifugal concentrator characterized by: