KR0156262B1 - Sedimentation centrifuge containing screw conveyor with fins - Google Patents

Abstract

The sedimentation centrifuge has a bowl from which the raw material mixture, ie the solid-liquid mixture, is fed from the feed pipe. When the bowl is rotated at high speed, the heavy solids move radially outward and settle on the inner wall of the bowl.

The solid particles are then discharged through the outlet outlet passage of the bowl by a screw conveyor in the bowl. The pins on the screw conveyor allow the liquid to be separated into the middle and hard phases while the bowl is rotating with good separation efficiency.

The separated heavy and hard fluid is ejected from the bowl through the respective passages to the outside.

Description

Sedimentation centrifuge

1 is a longitudinal sectional view of the sedimentation centrifuge according to the present invention,

FIG. 2 is a partially enlarged longitudinal sectional view of the pin and screw conveyor of the sedimentation centrifuge shown in FIG. 1,

3 is a partially enlarged longitudinal sectional view of a pin and screw conveyor according to another aspect of the present invention.

The present invention relates to a sedimentation centrifuge for separating solid particles and liquid mixtures into solids and liquid phases, and more particularly, for separating solids and mixtures of two liquid phases, that is, medium and hard liquids, into solid particles, solid and hard liquids. It relates to a settling centrifuge.

Until now, centrifuges or centrifugal separators have been used to separate solid particles and liquid mixtures into solids and liquid phases, or to separate mixtures of solid particles and heavy and hard liquids into solid particles, solid and hard liquids.

Disk decanters (also known as cone disk decanters), which are typically used for centrifugal sedimentation, have many hollow cone disks with truncated cones. In the case where the solid content of solid-liquid mixture of raw material slurry is separated as a disc decanter, the solid particles accumulated in the mixture block the gap between the discs and the disc decanter becomes inoperable. To prevent this from happening, for example, a screw decanter is used to reduce the amount of solid particles contained in the mixture, and then the mixture needs to be separated into solids and liquids with a disk decanter.

However, this method requires two decanters to be connected in series. Moreover, the energy consumed in the decanter is too much and wasteful because the mixture must be separated under twice the centrifugal force.

The present inventors have settled the centrifugal separator which separates solid particles and liquid mixture into solid and liquid phase, and also as disclosed in Japanese Patent No. 1,007,732 (Japanese Patent Publication No. 054961/75) and Japanese Patent Publication No. 152556/87. A settling centrifuge is proposed for separating solid particles and a mixture of two liquid phases, that is, a solid and a hard liquid, into a solid, a solid and a hard liquid. The proposed settling centrifuge (also called screw decanter with double slope) has a frustoconical bowl for discharging the settled solid particles. The bowl has an inner wall inclined at a large angle and then a small angle along the direction of discharging the accumulated solids with respect to the central axis of the bowl. The inner wall surface of the bowl, which is a double inclined surface, facilitates the transfer of solids to the ends of the bowl and also allows the liquid to be separated from the solid particles smoothly.

The structure of the bowl also contributes to an increase in the amount of raw material stagnated in the centrifuge for increased time. This increases the accuracy of the centrifuge separation and the processing capacity of the centrifuge per unit time.

The inventors have found that there are many improvements to be made in view of the processing capacity of the centrifuge, the accuracy of separation and the amount of energy required in actual use.

More specifically, as mentioned above, dex decanters are often inoperable when settled solids prevent gaps between discs when the solids content is high in the raw material. This problem can be avoided by first using a screw decanter to reduce the content of solids in the slurry and then treating the slurry in a disc decanter.

Therefore, it is necessary to connect two expensive decanters or centrifuges in series with each other. As a result, the decanter needs to apply twice as much centrifugal force as the energy consumption is too much.

The double decanter screw decanter proposed by the present inventors can finish the separation process when the slurry is passed only once through the centrifuge, whereas in practical use of the proposed decanter the proposed decanter uses a series connected centrifuge. There was no advantage over that expected, and there is a need to further improve the aspect of energy consumption in applications requiring processing capacity and accurate phase separation.

It is an object of the present invention that there is no breakage due to blockage between discs caused by a slurry or mixture with a high content of solids, the slurry can be separated with high precision, energy consumption is reduced, and a relatively large amount of raw material It is to provide a sedimentation separator that can be separated with high accuracy by applying centrifugal force of only a short period.

According to the invention, the settling centrifuge has a hollow cylindrical body rotatable about its central axis, a feeder for supplying a solid-liquid mixture to the hollow cylindrical body, and an inner wall inclined at a greater angle to the central axis. A first hollow truncated conical portion having a large diameter aperture between the large diameter openings connected adjacent one end of the hollow cylindrical body and a small diameter opening end axially opposed to the large diameter opening end, the interior being inclined at a smaller angle to the central axis A hollow cylindrical end having a wall surface and a continuous opening adjacent to the small diameter opening end of the first hollow truncated conical portion and opposing opening end which is a non-outlet, wherein the opening end has the hollow cylindrical body while the hollow cylindrical body is rotating; A second hollow theft circle located at or below the free liquid level of the solid-liquid mixture that is cylindrical in the body. Located in the vertebral portion, the hollow cylindrical body and the first and second hollow truncated conical portions, for transporting the sedimented solids separated from the solid-liquid mixture from the hollow cylindrical object to the spout via the first and second hollow truncated conical portions. Mounted on a screw conveyor, an embankment device at the end of the hollow cylindrical body remote from the spout and for controlling the outflow of the liquid separated from the solid-liquid mixture, a spout device for spouting the outflow of liquid, and a screw conveyor It consists of at least one pin located in the space between rotations of the blades of the screw conveyor and inclined to the central axis.

The embankment is located at the distal end of the hollow cylindrical body away from the spout and at the distal end of the hollow cylindrical body remote from the controlling first dike and spout which separates the heavy liquid separated from the solid-liquid mixture and separated from the solid-liquid mixture. It may contain a second dike that regulates the outflow of the hard liquor.

The ejector can eject the effluent of each of the heavy and hard fluids. A skimming method can also be used for the purpose of ejecting liquids.

The above and other objects, features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings which illustrate preferred embodiments of the present invention through examples.

As shown in FIG. 1, the three-phase separator includes a feed pipe 1 extending axially and open in a large diameter cylindrical portion of the bowl 2 that constitutes a hollow cylindrical momme.

The raw slurry or solid-liquid mixture to be separated consists mainly of solids and heavy and hard liquids, and is fed through feed tube 1 and hole 12 while bowl 2 is rotating at high speed. The solid particles contained in the mixture move radially outward toward the inner wall of the bowl 2 under the centrifugal force generated by the high speed rotation of the bowl 2.

Bowl 2 has an opening 4 at the periphery of the feed duct and defines opening 4 as the outlet. The bowl 2 covers the screw conveyor 3 which is arrange | positioned densely inside and extends axially between the opposing ends of the bowl 2. As shown in FIG. Solid particles settled on the inner wall surface of the bowl 2 are transferred to the spout by the screw conveyor 3 rotating at a speed different from the speed at which the bowl 2 rotates. The solid particles are then discharged from the outlet through the discharge passage 5 to the outside of the image separator.

Bowl 2 has a double inclined portion partially positioned around one end of screw Kenvey 3 installed around the feed tube. The double inclined portion has a first truncated conical portion and a large diameter opening end in which the inner wall surface is inclined at a large angle with respect to the central axis of the bowl 2, and the large diameter opening end is connected adjacent to one end of the cylindrical portion of the bowl 2. A second truncated conical portion is connected adjacent to the small diameter opening end of the first truncated conical portion and the inner wall surface is inclined at a small angle with respect to the central axis of the bowl 2. The large diameter open end of the second end conical portion is positioned at or below the free or free liquid level of the conical solid-liquid mixture produced while Vol 2 rotates. The opposite open end of the second truncated conical portion serves as ejection end 4.

The second theft cone portion includes jade 6 located near the ejection end and above the level of the mixture in bowl 2.

Just before the precipitated solid particles reach jet stage 4, the solid particles pass through jade 6, where the residual liquid is almost removed from the solids.

The three-phase separator also extends in parallel and includes a number of helical pins 7 located between the rotations of the vanes of the screw conveyor 3, which are mounted on the screw conveyor shaft. The pin 7 is inclined with respect to the free axis of the cylindrical solid-liquid mixture in the bowl 2 while the bowl 2 is rotated at high speed.

Most of the mixture supplied to the separator flows along the blades and pins 7 of the screw conveyor 3 and is thus resisted by friction with it. The mixture thus flows to the area around the inner wall of the bowl 2 around the screw conveyor 3 and pin 7. Since the area near the inner wall surface in the bowl 2 is a space away from the axis around which the screw conveyors 3 and 7 rotate, the mixture flowing into this area is subjected to a large centrifugal force and can be separated by its efficiency.

The three phase separator may have one or more and twenty spiral pins. The distance between the radially outer end of the pin and the inner wall surface of the bowl 2 ranges from 5 mm to 100 mm and the thickness of the pin ranges from 0.5 mm to 2 mm.

The distance between the pins should be kept as short as possible to reduce the reversal and side settling distances of the particles in the mixture, resulting in increased settling efficiency. If the distance between the pins is too short, the gaps between the pins will be blocked by solid particles, and the particles will not be released from the pins. Therefore, the distance between the pins should be determined according to the characteristics of the solid-liquid mixture to be treated.

If the solid-liquid mixture contains many solids, the distance between the radially outer end of the fin and the inner wall surface of the bowl 2 is preferred. If the solid-liquid mixture contains less solids, the distance between the radial outer end of the fin and the inner wall surface of the bowl 2 is shorter, so it is desirable to vaporize the working surface area of the fin to increase the separation efficiency.

It is therefore desirable to use a plurality of screw conveyors with different radial length pins and to select one of the screw conveyors to be used depending on the solids content of the solid-liquid mixture to be treated. Since the centrifuge or separator according to the invention is in the shape of a migration projection decanter, the distance between the free liquid surface of the mixture flowing through the bowl 2 and the inner wall surface of the bowl 2 is large. Therefore, the length of the pin inserted into the mixture in bowl 2 should be long to increase the accuracy and capability of separation.

The angle at which the pin is inclined to the central axis of the bowl 2, ie the shaft of the screw conveyor, must be small because it reduces the settling distance and increases the separation efficiency. However, the angle is so small that the gaps between the fins are blocked by the solid particles so that the solid particles cannot be ejected from between the fins.

The angle is preferably in the range of 30-80 degrees. The surface of the fins may have smooth or smooth radiated flaws or ridges to increase separation efficiency to increase surface area. The fins of the other aspect are mounted in a group of thin plates and mounted on a screw conveyor shaft parallel thereto, and the free liquid branches of the mixture in the bowl 2 extend obliquely radially outwardly from the screw conveyor shaft while the bowl 2 rotates. It can be a group of thin plates, and the screw conveyor blades can be wound at the outer ends.

The centrifugal force applied to the mixture into which pin 7 is inserted is relatively small. However, due to the short distance between pin 7 and also the pin 7 and screw conveyor blades, that is, the settling distance, sedimentation or entanglement of medium and hard particles such as suspended and suspended particles as shown in FIG. This improves the accuracy of separation.

In particular, when the mixture consists of solids, solids and hard fluids, the heavy and hard fluids can be separated highly precisely, forming an interface as shown in Fig. 2 due to the coalescence caused by contact with pin 7. The sediment which has been separated and passed through bowl 2 exits bank 8 and is ejected through outlet 9 to the outside of the separator. Similarly, the heavy liquid separated and passed through Bowl 2 exits bank 10 and is ejected through outlet 11 to the outside of the separator. Thus, levees 8 and 10 play a role in controlling the inference of the middle and hard fluids.

2 is an enlarged view of the blade and pin 7 of the screw conveyor 3. Figure 2 also shows the shape of the particles that settle and actively move between the pins 7.

3 shows a screw conveyor 3 and a pin 7 according to another aspect. The vanes and pins 7 of the screw conveyor 3 are inclined at different angles in a direction opposite to the direction in which the screw conveyor vanes and pins 7 shown in FIG. 2 are tilted.

In another aspect, the screw conveyor blades are arranged parallel to this, in the form of a group of thin plates mounted on a screw conveyor extending radially outwardly from the screw conveyor to the free liquid level of the mixture in the rotating bowl 2. It is preferable that the outer end of the thin plate is wound.

Comparative Examples 1 and 2 for separating the raw material mixture using a conventional decanter and an example for separating the raw material mixture using the three-phase separator according to the present invention will be described below.

Comparative Example 1

The raw material mixture to be separated is screw-pressed in a sardine fish factory to produce 1000 liters per hour and passed through a rotating body. The raw material mixture was 30.8 volume% oil, 61.5 volume% water. It is composed of 7.7% by volume solids. The raw material mixture is fed to a three-phase separation decanter having an internal diameter of 250 mm and having a conventional single slope. The raw material mixture was separated under a centrifugal force of 95 ° C and 3000G, and the water content was 2.5% or less, the solid content was 2.0% or less, the remainder was an oily liquid, 98.7% water, 1.3% solids, 0.83% oil. To obtain a cake consisting of a solid solution of water, 70% by weight of water, 3.0% by weight of oil and the remainder as a solid.

Hardeners are sold in fish oil after finishing with a cone-dsk decanter. The heavy liquid is concentrated to a high protein concentration and the cake is dried in a dryer.

The water content in the conventional liquid obtained by the conventional three-phase decanter is 1.8% by volume, which is a high value. Solids settled under centrifugal force in the liquid solution were 2.0% by volume, which is also high. Hardening liquids are not readily available as fish oil products. The oil in the solid solution is 0.83% by weight and the solid precipitated under centrifugal force is 1.3% by volume. These values are also high and heavy liquids cause the tubes to become hot when concentrated.

If the raw material mixture is treated only once with a three-phase decanter, the conventional three-phase decanter cannot be practically used as a three-phase separator. To obtain a hardener that can be used as a fish oil product, the hardener must be subsequently treated with a cone disc decanter.

The resulting heavy liquid causes the hot tube to be destroyed when it is concentrated.

Comparative Example 2

The sardines are screw pressed and passed through a rotor to produce 3000 liters per hour of the raw material mixture to be separated. The crude mixture consists of 15.6 to 31.5% by volume of oil, 3.2 to 12.1% by volume of solids, and the remainder of water. The raw material mixture is fed to a three phase separation decanter having an internal diameter of 320 mm and having a conventional single inclined plane. The feed mixture was separated under a centrifugal force of 90 ° C. and 3000G, yielding 0.15% by weight of water, a small amount of solids, a hardened oil with a remainder, 0.1 to 0.26% by weight, 0.3% by volume of solids, and a solid solution with water and oil. 1.8 weight%, about 65 weight% of water are obtained, and the remainder becomes a solid cake.

Hardeners are of high quality and can be shipped directly to fish oil products. The heavy liquid and the cake are treated in the same manner as in Comparative Example 1. The protein concentrate obtained in heavy solution is superior in quality to the protein concentrate obtained in Comparative Example 1 because it does not destroy the hot tube when concentrated. Kate dried faster than the cake in Comparative Example 1.

EXAMPLE

The raw material mixture used in Comparative Example 2 is fed to the three phase separator according to the present invention in a time stage of 5100 L. The three-phase separator used has a screw conveyor containing a bowl having an inner diameter of 320 mm and six pins 20 mm away from the inner wall of the bowl.

The pins having a height of 70 mm in the screw conveyor shaft are inclined at an angle of 45 degrees as shown in FIG. 2 and are spaced 60 mm apart from each other with equal spacing between the rotating surfaces of the screw conveyor blades. The raw material mixture was separated at 93 ° C. under a centrifugal force of 3000 G, yielding 0.12% by weight of water, a small amount of solids, a hardened oil with a remainder, 0.1 to 0.2% by weight, 0.3% by volume solids, a hardened water with a remainder, and 1.8% by oil. %, Water of about 65% by weight, the remainder is a solid cake.

Hardeners are of high quality and can be shipped directly as fish oil products. The solid solution and the cake were treated in the same manner as in Comparative Example 2. The protein concentrate obtained in the heavy liquid is as good as the protein concentrate obtained in Comparative Example 2. The cake dried faster than the cake in Comparative Example 2.

The three phase separator used in the examples has substantially the same specifications as that of the double oblique three phase separation decanter used in Comparative Example 2. However, since the pin is installed in the screw conveyor, the processing capacity of the three-phase separator in the example is 1.7 times higher than that of the double inclined three-phase decanter in Comparative Example 2 (5100 L / time zone 3000 L / hour). The protein concentrated diluted aqueous solution is higher in purity than that in Comparative Example 2. (Moisture: 0.12% by weight to 0.15% by weight in oil, 0.1 to 0.2% by weight in heavy fluid, 0.1 to 0.26% by weight)

It is determined that the presence of pin 7 adversely affects the stability of the dynamic interface boundary between hard and heavy liquids. However, the experimental results of the examples and comparative examples shown above show that the enhanced quality of the separated hard and heavy liquids demonstrates the presence of a stable dynamic interface boundary between the hard and heavy liquids.

While any preferred aspect of the invention has been disclosed and described in greater detail, it should be understood that various changes or modifications may be made without departing from the scope of the claims of the invention.

Claims (2)

A hollow cylindrical body rotatable about its central axis; A feeder for supplying a solid-liquid mixture to the hollow cylindrical body; A first hollow cutaway having an inner wall surface inclined at a larger angle to the central axis and having a large diameter opening end connected adjacent to one end of the hollow-cylindrical body and a small diameter opening end opposed to the large diameter opening end axially; Conical portion; Said open end having an inner wall inclined at a smaller angle to said central axis and having an open end and an ejection opening that are continuously connected adjacent to a small diameter open end of said first hollow frusto-conical portion, said open end A second hollow truncated conical portion located at or below the free liquid level of the solid-liquid mixture that is cylindrical in the hollow cylindrical body while the hollow cylindrical body is rotating; A settling solid conveyor moving on the hollow cylindrical body and the hollow first and second hollow truncated conical portions and the jetting port separated from the solid-liquid mixture through the first and second hollow truncated cone portions in the hollow cylindrical body; A dike device for controlling the outflow of liquid separated from said solid-liquid mixture at an end of said hollow cylindrical body away from said spout; An ejecting device for separating out the liquid effluent; And at least one pin topjacked on the screw conveyor and positioned in the space between rotations of the screw conveyor blades and inclined to a central axis. 2. The apparatus of claim 1, further comprising: a hollow cylindrical body rotatable about its central axis; A feeder for supplying a solid-liquid mixture to the hollow cylindrical body; A first hollow truncation having an inner wall surface that is inclined at a greater angle to the central axis and having a large diameter opening end connected adjacent to one end of the hollow cylindrical body and a small diameter opening end opposite in axis to the large diameter opening end; Conical portion; Said opening end having an inner wall inclined at a smaller angle to said central axis and having an opposing opening end, which is an opening end and an ejection opening continuously connected to a small diameter opening end of said first hollow truncated conical portion, said opening end being A second hollow frusto-conical portion located at or below the free liquid surface of the cylindrical solid-liquid mixture in the hollow cylindrical body while the hollow cylindrical body is rotating; A screw conveyor positioned in the hollow cylindrical body and the first and second hollow truncated conical portions and moving the sedimented solids separated from the solid-liquid mixture from the hollow cylindrical body to the spout via the first and second hollow truncated conical portions; A first embankment positioned at the distal end of the hollow cylindrical body away from the jet port and controlling the outflow of the heavy liquid separated from the solid-liquid mixture; A second embankment positioned at the distal end of the hollow cylindrical body away from the jet port and controlling the analogy of hard fluid separated from the solid-liquid mixture; An ejecting device for ejecting the effluent of the heavy liquid and the wide area; And at least one pin mounted on the screw conveyor and positioned in space between rotations of the screw conveyor blades and inclined to a central axis.