Disk-type centrifugal separator

Abstract

The present invention provides a disc-type centrifuge that can prevent mist from the working fluid from entering the drive section and can use corrosive liquids such as acidic aqueous solutions as the storage fluid and working fluid. [Solution] A gap C is formed between the inner surface of the upper half of the center base 5 and the rotating shaft 11. A small chamber B is formed on the inner side of the lower half of the center base 5, which is larger than the gap C and communicates with the gap C, as well as with the lower drive section area D. Air is continuously supplied from the air supply source to the drive section area D and flows continuously from the drive section area D into the small chamber B. The air in the small chamber B is discharged from an exhaust hole 54 formed in the center base 5.

Description

Technical Field

[0005]

[0001] The present invention relates to a disk centrifuge configured to stack a large number of conical separation disks in a bowl, rotate them at high speed, and separate the processed material supplied into the bowl.

Background Art

[0002] As one type of centrifuge that separates processed materials using centrifugal force, there is known a centrifuge (disk centrifuge) in which a large number of conical separation disks are stacked in a bowl with a slight gap between them and rotated at high speed to apply centrifugal force to the processed material.

[0003] FIG. 3 is a cross-sectional view schematically showing the internal structure of a conventional general disk centrifuge 1. In this disk centrifuge 1, a bowl 2 having an upper half formed in a conical shape is disposed within a casing 3, and a large number of conical separation disks 12 are disposed in the bowl 2 in a stacked state with a slight gap formed therebetween. The bowl 2 is coupled to the upper end of a vertically disposed rotating shaft 11 that penetrates the bottom of the casing 3 (casing bottom �1), and the bowl 2 and the built-in separation disks 12 are configured to rotate at high speed by a rotational driving force supplied to the rotating shaft 11 from a motor (not shown).

[0004] When the stock solution of the processed material is introduced from a stock solution supply pipe 13 disposed above the bowl 2 into the space (separation chamber 21) within the bowl 2, due to the action of centrifugal force, components with a large density in the processed material (e.g., solid sludge, heavy liquid, etc.) move to the radially outer region S1 within the separation chamber 21, and components with a small density (e.g., clarified liquid, light liquid, etc.) move to the radially inner region S2 within the separation chamber 21. By discharging them through separate paths, the processed material can be separated into a phase of components with a large density (heavy phase) and a phase of components with a small density (light phase). (There is also a disk centrifuge that can separate into three phases: solids heavier than the liquid, heavy liquid, and light liquid.)

[0005] The disk-type centrifuge 1 has the advantage of being able to efficiently separate large quantities of material in a short time, as it can secure an extremely large separation and settling area relative to the installation area by stacking a large number of separation disks 12 so that small gaps are formed between them.

[0006] Furthermore, when the disk-type centrifuge 1 shown in Figure 3 is operated, the heavy phase separated from the material accumulates in region S1 (radially outer region) within the separation chamber 21 as the separation process progresses. However, this heavy phase can be instantly discharged to the outside of bowl 2 while the disk-type centrifuge 1 is running, that is, while bowl 2 is rotating at high speed, by operating the heavy phase discharge mechanism, which includes the movable bottom plate 4 that partitions the lower side of the separation chamber 21.

[0007] To explain this heavy phase discharge mechanism in more detail, first, the movable bottom plate 4 is configured to move up and down between a closed position (a closed state in which the separation chamber 21 is not opened radially outward) where the outer peripheral upper edge 41 located radially outward of the separation chamber 21 is in close contact with the upper half of the bowl 2 (upper half of the bowl 23), as shown in Figure 4, and an open position (a state in which the separation chamber 21 is opened radially outward) where the outer peripheral upper edge 41 is slightly lowered from the closed position and separated from the upper half of the bowl 23, as shown in Figure 5.

[0008] Furthermore, as shown in Figure 4, a liquid storage passage 51 for supplying liquid storage (liquid that maintains the movable bottom plate 4 in the closed position (see Figure 4)) into the lower half of the bowl 22, and a hydraulic fluid supply passage 52 for supplying hydraulic fluid (liquid that drains the liquid storage and displaces the movable bottom plate 4 to the open position (see Figure 5)) into the lower half of the bowl 22 are formed inside the center base 5 located in the center of the bottom of the casing 31.

[0009] Furthermore, within the lower half 22 of the bowl, there is a first annular channel 24 located radially outside the outlet of the storage liquid supply channel 51 (radially outside the bowl 2), a second annular channel 25 located radially outside the outlet of the working fluid supply channel 52, a storage chamber 26 communicating with the first annular channel 24 below the movable bottom plate 4, a drainage channel 27 communicating with the storage chamber 26 radially outside the storage chamber 26, and a working fluid channel 28 communicating with the second annular channel 25.

[0010] Furthermore, a valve body 6 for opening and closing the drain channel 27 is located within the lower half 22 of the bowl. As shown in Figure 4, the valve body 6 is configured to close the drain channel 27 when it is in its outermost radial position, and to open the drain channel 27 by moving from this position to a radially inward position. During operation of the disc-type centrifugal separator 1 (when the bowl 2 rotates), the valve body 6 is biased radially outward by centrifugal force. Therefore, during operation, the drain channel 27 is basically kept closed by the valve body 6.

[0011] When performing separation using this disk-type centrifuge 1, first, with the bowl 2 rotating at high speed, the stored liquid is supplied into the lower half 22 of the bowl from below the bottom 31 of the casing via the stored liquid supply passage 51. As a result, the stored liquid flows into the storage chamber 26 through the first annular passage 24 and is stored in the storage chamber 26 without being discharged through the drainage passage 27 closed by the valve body 6.

[0012] The high-speed rotation of bowl 2 exerts a large centrifugal force on the liquid stored in the storage chamber 26, causing the pressure inside the storage chamber 26 to rise. This pressure pushes the movable bottom plate 4 upward, and the upper edge 41 on the outer circumference is strongly pressed against the upper half of the bowl 23, creating a tight seal. As a result, the separation chamber 21 becomes closed (not open radially outward).

[0013] When the material to be processed is introduced into the closed separation chamber 21 and separated, and a certain amount of the separated biphase has accumulated in the separation chamber 21 (region S1), as shown in Figure 5, the working fluid is supplied from below the casing bottom 31 through the working fluid supply passage 52 into the lower half of the bowl 22. Then the working fluid flows into the working fluid passage 28 through the second annular passage 25.

[0014] The hydraulic fluid passage 28 is in communication with the cylinder 62 that houses the piston 61 of the valve body 6, and is configured to allow the hydraulic fluid to flow into the cylinder 62 from the radially outer side of the piston 61. Therefore, when hydraulic fluid is supplied to the hydraulic fluid passage 28, the piston 61 inside the cylinder 62 is pushed radially inward by the hydraulic fluid, and the valve body 6 moves radially inward.

[0015] As the valve body 6 moves radially inward, the drain channel 27 is opened, as shown in Figure 5, and the liquid stored in the storage chamber 26 is discharged to the outside of the bowl 2 through the drain channel 27. As a result, the pressure in the storage chamber 26 that had been pushing the movable bottom plate 4 upward decreases (becomes lower than the pressure in the separation chamber 21), the movable bottom plate 4 descends, and a gap is formed between the outer peripheral upper edge 41 and the upper half of the bowl 23, and the distillate in the separation chamber 21 is discharged to the outside of the bowl 2 through this gap.

[0016] The heavy phase discharged from bowl 2 is captured by an annular heavy phase recovery section 32 (see Figure 3) formed on the outermost periphery of casing 3 (radially outside bowl 2), and discharged outside the machine through the discharge port 34 (see Figure 3). Meanwhile, the light phase is continuously discharged outside the machine through a light phase recovery section 15 (see Figure 3) located above bowl 2.

[0017] Furthermore, the supply time of the working fluid to the working fluid supply passage 52 is usually sufficient at about 5 seconds. After that, the storage fluid is supplied again to the storage fluid supply passage 51 and stored in the storage chamber 26, and the movable bottom plate 4 is returned to the closed position, allowing the separation process to continue while the bowl 2 is rotating at high speed. [Prior art documents] [Patent Documents]

[0018] [Patent Document 1] Japanese Unexamined Patent Publication No. 56-108550 [Patent Document 2] Japanese Patent Publication No. 2019-107622 [Patent Document 3] Japanese Patent Publication No. 2024-32074 [Overview of the Initiative] [Problems that the invention aims to solve]

[0019] In conventional disk-type centrifuges 1, water (tap water, industrial water, etc.) is used as the working fluid to operate the heavy phase discharge mechanism. Therefore, if the material to be separated (the material supplied into bowl 2) contains a substance that may react and denature (for example, solidify) upon contact with water, when the separation process progresses and a certain amount of heavy phase has accumulated, operating the heavy phase discharge mechanism to discharge the heavy phase from bowl 2 may cause the heavy phase to denature due to a reaction with the water (working fluid, etc.) simultaneously discharged from the lower half 22 of the bowl.

[0020] Furthermore, while using an acidic aqueous solution instead of water as the storage fluid and working fluid can sometimes solve the problem of the degradation of the biphase discharged from bowl 2, in this case, mist of the working fluid (acidic aqueous solution) supplied to the lower half 22 of the bowl from the storage fluid supply passage 51 and the working fluid supply passage 52 may enter the area near the rotating shaft 11 or the area where the motor, gears, bearings, etc. (not shown) that supply rotational driving force to the rotating shaft 11 are located (the drive section area), potentially corroding these metal components.

[0021] The present invention aims to solve the problems of the prior art described above and provides a disk-type centrifuge that can prevent mist such as working fluid from entering the drive section and can use corrosive liquids such as acidic aqueous solutions as the storage fluid and working fluid.

Means for Solving the Problem

[0022] The disk centrifuge according to the present invention is configured such that a bowl disposed in a casing and a plurality of conical separation disks disposed in the separation chamber of the bowl in a stacked state while forming a gap rotate at high speed together with a vertically disposed rotating shaft. An annular center base having a reservoir liquid supply path and a working liquid supply path formed inside is disposed below the bowl so as to surround the outside of the rotating shaft. By supplying the working liquid to the working liquid supply path, the valve body in the bowl is operated, and a movable bottom plate that partitions the lower side of the separation chamber is lowered to open the separation chamber radially outward. The heavy phase separated in the separation chamber can be discharged to the outside of the bowl and is configured to be recovered by a recovery unit disposed outside the bowl. A gap (C) is formed between the inner peripheral surface of the upper half of the center base and the rotating shaft. A chamber (B) larger than the gap (C) is formed on the inner peripheral side of the lower half of the center base, communicates with the gap (C), and communicates with the region (D) of the lower drive unit. Air is continuously supplied from an air supply source to the region (D) of the drive unit and is configured to continuously flow from the region (D) of the drive unit into the chamber (B). The air in the chamber (B) is discharged from an exhaust hole formed in the center base or is sucked by a suction means through the exhaust hole and is configured to be forcibly discharged.

[0023] In this disk centrifuge, it is preferable that the suction amount of the air in the chamber (B) by the suction means is set to be less than the supply amount of the air to the region (D) of the drive unit. Also, in the chamber (B), a flange protruding radially outward from the outer peripheral surface of the rotating shaft is disposed, and an annular fin protruding from the outside radially inward is formed inside the center base, so that the chamber (B) has a labyrinth structure.

[0024] Furthermore, it is preferable that the outer peripheral surface of the rotating shaft is covered by the cover member up to a position below the lower edge of the inner peripheral surface of the bowl, below the storage liquid supply path and the operating liquid supply path, or below the center base.

Advantages of the Invention

[0025] The disk type centrifuge according to the present invention can prevent the mist of the storage liquid and the operating liquid generated during the discharge of the heavy phase from entering the area of the drive unit, and even when a corrosive liquid such as an acidic aqueous solution is used as the storage liquid and the operating liquid, it is possible to prevent the metal components such as bearings, motors, and gears arranged in the drive unit from corroding. Further, by covering the outer peripheral surface of the rotating shaft with the cover member, it is possible to prevent the corrosion of the outer peripheral surface of the rotating shaft.

Brief Description of the Drawings

[0026] [Figure 1] FIG. 1 is an enlarged cross-sectional view showing the internal structure of the disk type centrifuge 1 according to the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view of the vicinity of the rotating shaft 11 of the disk type centrifuge 1 shown in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view schematically showing the internal structure of a conventional general disk type centrifuge 1. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing the internal structure of the disk type centrifuge 1 shown in FIG. 3, and shows a state (closed state) in which the movable bottom plate 4 is in the closed position. [Figure 5] FIG. 5 is an enlarged cross-sectional view showing the internal structure of the disk type centrifuge 1 shown in FIG. 3, and shows a state (open state) in which the movable bottom plate 4 is in the open position.

Embodiments for Carrying Out the Invention

[0027] Hereinafter, an embodiment of the "disk-type centrifuge" according to the present invention will be described with reference to the attached drawings. Figure 1 is an enlarged cross-sectional view showing the internal structure of the disk-type centrifuge 1 according to the present invention. This disk-type centrifuge 1 has the same basic configuration as the conventional disk-type centrifuge 1 shown in Figures 3 to 5, performs separation processing of materials by the same principle, and can discharge the heavy phase from the separation chamber 21 by the same heavy phase discharge mechanism.

[0028] In other words, the material to be processed introduced into the separation chamber 21 can be separated into a heavy phase and a light phase by the action of centrifugal force. Furthermore, by supplying working fluid during operation, the movable bottom plate 4 is lowered to instantaneously open the separation chamber 21, allowing the heavy phase to be discharged between the upper outer edge 41 of the movable bottom plate 4 and the upper half of the bowl 23. In addition, the light phase can be continuously discharged through a different path (from the light phase recovery section 15).

[0029] Figure 2 is an enlarged cross-sectional view of the vicinity of the rotating shaft 11 of the disc-type centrifugal separator 1 shown in Figure 1. As shown, a circularly formed center base 5 is positioned below the lower half of the bowl 22 (bowl 2) (between it and the bearing 14), surrounding the outside of the rotating shaft 11 (so that the rotating shaft 11 passes through the center of the center base 5).

[0030] The uppermost part of the center base 5 is configured to extend to a position radially inward of the lower half of the bowl 22 (a position between the lower half of the bowl 22 and the rotation axis 11). A reservoir fluid supply passage 51 and a working fluid supply passage 52 are formed inside the upper half, including this uppermost part, so that the reservoir fluid and working fluid can be supplied from the radially inward position of the lower half of the bowl 22.

[0031] This center base 5 is fixed by the machine frame and is configured not to come into contact with the high-speed rotating shaft 11 and bowl 2. Therefore, as shown in Figure 2, a gap C is formed between the inner surface of the upper half of the center base 5 and the rotating shaft 11, and an annular chamber B with a larger volume than the gap C is formed on the inner side of the lower half of the center base 5. This chamber B is in communication with the upper gap C and also with the lower drive section region D (the region where the bearing 14 supporting the rotating shaft 11 and the motor, gears, etc. (not shown) that supply rotational driving force to the rotating shaft 11 are located).

[0032] As described above, in the conventional disk-type centrifuge 1 shown in Figures 3 to 5, when the heavy phase is discharged, mist from the storage liquid and working fluid may enter the area near the rotating shaft 11 and the drive section. If corrosive liquids are used as the storage liquid and working fluid, there is a possibility that metal components such as the rotating shaft 11 may be corroded. However, the disk-type centrifuge 1 of this embodiment is configured to suitably avoid such problems. This point will be described in detail below.

[0033] The rotating shaft 11 is fitted with cover members 7 (first cover member 71 and second cover member 76). These cover members 7 (71, 76) are all made of a non-metallic material such as synthetic resin (e.g., polytetrafluoroethylene) which has excellent heat resistance and wear resistance, and each has cylindrical portions 72, 77 that cover the outer circumferential surface of the rotating shaft 11 and flanges 73, 78 that protrude radially outward. The cover members 7 can also be made of a corrosion-resistant metal (e.g., titanium).

[0034] The cylindrical portion 72 of the first cover member 71 and the cylindrical portion 77 of the second cover member 76 are connected so as to be continuous in the axial direction of the rotating shaft 11. Furthermore, the upper edge of the cylindrical portion 72 of the first cover member 71 extends to a position above the reservoir fluid supply passage 51 and the working fluid supply passage 52 formed inside the center base 5, and is connected to the lower edge of the inner circumferential surface (the surface in contact with the outer circumferential surface of the rotating shaft 11) of the lower half of the bowl 22 (bowl 2), and the lower edge of the cylindrical portion 77 of the second cover member 76 extends to a position below the reservoir fluid supply passage 51 and the working fluid supply passage 52 (preferably below the center base 5, and immediately above the bearing 14). In this way, the outer circumferential surface of the rotating shaft 11 is covered by the cover member 7 from the lower edge of the inner circumferential surface of the lower half of the bowl 22 to the immediately above the bearing 14.

[0035] The flange 73 of the first cover member 71 and the flange 78 of the second cover member 76 are arranged at a predetermined distance in the vertical direction (axis direction of the rotation axis 11) within the small chamber B formed inside the lower half of the center base 5. An annular fin 53 is also formed inside the center base 5. This fin 53 is configured to protrude radially from the outside to the inside so that its inner circumference enters the space between the flanges 73 and 78. In this way, the small chamber B inside the center base 5 forms a labyrinth structure with the flanges 73 and 78 and the fin 53 creating a path that meanders radially from the inside to the outside, then from the outside to the inside, and then from the inside to the outside.

[0036] Furthermore, the drive section region D, where the bearing 14 and other components are located, is configured to be continuously supplied with air from an air supply source (such as an air pump) (not shown). Since region D is closed except for the gap of the bearing 14, the air pressure inside region D is higher than atmospheric pressure, and the supplied air flows continuously from region D through the gap of the bearing 14 towards the small chamber B inside the center base 5.

[0037] Furthermore, the small chamber B of the center base 5 is connected to a drive leakage drain (not shown) via an exhaust port 54 formed inside the center base 5 and a hose 55 (or pipe) attached to its outer opening. A suction means (such as an ejector or suction pump) is positioned in the middle of the hose 55 (or between the hose 55 and the drive leakage drain) to suck in the air inside the small chamber B and forcibly discharge it (send it to the drive leakage drain).

[0038] Furthermore, the suction force of the suction means is set to be less than the air supply pressure to region D. Also, during normal operation of the disk-type centrifuge 1, the liquid accumulates in the annular first annular channel 24 formed in the lower half 22 of the bowl, and the outer circumference of the uppermost part 56 of the center base 5 is configured to be in full contact (submerged) with the liquid in this first annular channel 24. As a result, the upper side of the gap C is sealed by the liquid in the first annular channel 24. Consequently, the air pressure in the small chamber B into which air continuously flows from region D of the drive unit, and in the gap C communicating with this small chamber B, is greater than atmospheric pressure.

[0039] Because the disk-type centrifuge 1 of this embodiment has the features described above, it is possible to prevent mist of the stored liquid and working fluid generated during the discharge of the heavy phase from entering the small chamber B in the center base 5 and the drive area D through the gap C. Furthermore, even if mist of the stored liquid and working fluid were to enter the gap C, the outer circumferential surface of the rotating shaft 11 is covered by the cover member 7, so it is possible to prevent the mist from coming into contact with the rotating shaft 11.

[0040] Therefore, even when corrosive liquids such as acidic aqueous solutions are used as the reservoir and working fluid in the disk-type centrifuge 1 of this embodiment, corrosion of metal components such as the rotating shaft 11, bearings 14, motor, and gears can be prevented. [Explanation of symbols]

[0041] 1: Disk-type centrifuge, 2: Bowl, 3: Casing, 4: Movable bottom plate, 5: Center base, 6: Valve body, 7: Cover component, 11: Axis of rotation, 12: Separable disk, 13: Stock solution supply pipe, 14: Bearings, 15: Light phase recovery unit, 21: Separation room, 22: Lower half of the bowl, 23: Upper half of the bowl, 24: First ring channel, 25: Second ring channel, 26: Storage chamber, 27:Drainage channel, 28: Working fluid flow path, 31: Casing bottom, 32: Heavy phase recovery unit, 34: Outlet, 41: Upper edge on the outer periphery, 51: Storage liquid supply channel, 52: Work fluid supply path, 53: Finn, 54: Exhaust vent, 55: Hose, 61: Piston, 62: Cylinder, 71: First cover member, 72: Cylindrical part, 73: Flange, 76: Second cover member, 77: Cylindrical part, 78: Flange, B: Komuro, C: Gap, D: Drive area

Claims

1. A bowl placed inside a casing, and numerous conical separation disks stacked with gaps between them and placed in the separation chamber of the bowl, are configured to rotate at high speed along a vertically positioned axis. An annular center base, with a reservoir fluid supply channel and a working fluid supply channel formed inside, is positioned below the bowl, surrounding the outside of the rotating shaft. In a disc-type centrifugal separator, the valve body inside the bowl is operated by supplying working fluid to the working fluid supply passage, causing a movable bottom plate partitioning the lower side of the separation chamber to be lowered, opening the separation chamber radially outward, and allowing the heavy phase separated inside the separation chamber to be discharged to the outside of the bowl, where it is recovered by a recovery unit located outside the bowl, A gap (C) is formed between the inner surface of the upper half of the center base and the axis of rotation. A small chamber (B) is formed on the inner circumference of the lower half of the center base, which is larger than the gap (C), communicates with the gap (C), and communicates with the area (D) of the lower drive section. Air is continuously supplied from the air supply source to the drive unit region (D), and is configured to flow continuously from the drive unit region (D) into the small chamber (B). A disc-type centrifugal separator characterized in that the air inside the small chamber (B) is discharged from an exhaust port formed in the center base.

2. The disc-type centrifugal separator according to claim 1, characterized in that the air inside the small chamber (B) is sucked in by a suction means and forcibly discharged through an exhaust port formed in the center base.

3. The disk-type centrifugal separator according to claim 1, characterized in that the amount of air drawn into the small chamber (B) by the suction means is set to be less than the amount of air supplied to the drive unit region (D).

4. The disc-type centrifugal separator according to claim 1, characterized in that a flange protruding radially outward from the outer surface of the rotating shaft is arranged within the small chamber (B), and an annular fin is formed inside the center base, protruding radially outward from the outside to the inside, thereby giving the small chamber (B) a labyrinth structure.

5. The disc-type centrifugal separator according to claim 1, characterized in that the outer circumferential surface of the rotating shaft is covered by a cover member from the lower edge of the inner circumferential surface of the bowl to a position below the reservoir fluid supply passage and the working fluid supply passage.

6. The disc-type centrifugal separator according to claim 1, characterized in that the outer circumferential surface of the rotating shaft is covered by a cover member from the lower edge of the inner circumferential surface of the bowl to a position below the center base.

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