JP6088106B1 - Centrifuge - Google Patents

Abstract

A centrifugal separator capable of preventing a feed tube from being broken at any of an operation start, a separation operation, and an operation end. A bowl (3) for solid-liquid separation of a treatment liquid by centrifugal force, a screw conveyor (4) for conveying a solid phase separated in the bowl toward a discharge port, and a treatment liquid in the bowl In the centrifuge provided with the feed tube (5), carbon fiber reinforced plastic (CFRP) is used as the main material forming the main body (51) of the feed tube. [Selection] Figure 1

Description

  The present invention relates to a centrifuge for solid-liquid separation of a processing liquid using centrifugal force, and more particularly to a centrifuge for supplying a processing liquid to a rotating bowl using a feed tube.

As a device for performing solid-liquid separation using centrifugal force, a centrifugal device called a decanter is known. FIG. 7 schematically shows the basic structure of the decanter. The horizontal decanter 1 includes a bowl 11 and a screw conveyor 12 that rotate about a horizontal axis.

  The bowl 11 is configured by a cylindrical body having one end side or both ends formed in a conical shape. The screw conveyor 12 is a rotary conveying means provided with screw blades 12a for conveying the separated solid phase. The screw conveyor 12 is hollow along the central axis of rotation, and a pipe-like feed tube 13 serving as a supply nozzle for the processing liquid to be centrifuged is inserted with a slight clearance so as not to contact the screw conveyor 12. ing. The processing liquid discharged from the tip of the feed tube 13 is supplied to the cavity in the screw conveyor 12, discharged from the supply hole 14 formed in the outer peripheral surface by the action of centrifugal force, and supplied into the bowl 11.

  In such a configuration, when the processing liquid is continuously supplied from the feed tube 13 and the bowl 11 is rotated at a predetermined rotational speed, the processing liquid is solidified into the liquid phase in the bowl 11 by the action of centrifugal force. And separated. The solid phase is conveyed toward one end side of the bowl 11 by the screw conveyor 12, separated from the liquid phase at the conical portion, and discharged through the solid phase outlet 15. On the other hand, the liquid phase (separated liquid) overflows from the opposite liquid phase outlet 16 and is discharged.

  The number of rotations of the bowl 11 when the centrifugal force necessary for performing solid-liquid separation is applied to the processing liquid (that is, the number of rotations during “separation operation”) can be adjusted as appropriate depending on the type and concentration of the processing liquid. However, as an example, it is controlled to a predetermined rotational speed selected within a range of 500 to 8000 rpm.

  By the way, when the horizontal decanter 1 having the above configuration is operated, the feed tube 13 made of metal such as stainless steel may be broken. Not only partial defects or cracks occur on the surface, but the feed tube is completely broken along the way. The breakage of the feed tube 13 tends to occur when the rotation speed of the bowl 11 is increased at the start of operation or when the rotation speed of the bowl 11 is decreased at the end of the operation, but can also occur during the separation operation. There is. If the feed tube 13 is broken, the temporary operation becomes impossible for replacement. Furthermore, the feed tube 13 is made of metal as described above, and the burden of replacement work is large.

Japanese National Patent Publication No. 10-512799 Special table 2012-529360 gazette

  The present invention has been made based on such circumstances, and the object thereof is to prevent the feed tube from being broken at any of the start of operation, the separation operation, and the end of operation. An object of the present invention is to provide a centrifugal separator.

The gist of the present invention is as follows.
(1) The centrifugal separator according to the present invention includes a bowl for solid-liquid separation of the treatment liquid by centrifugal force, a screw conveyor for conveying the solid phase separated in the bowl toward the discharge port, and a treatment in the bowl. A centrifuge provided with a feed tube for supplying a liquid is characterized in that carbon fiber reinforced plastic (CFRP) is used as a main material forming the main body of the feed tube. “Use of carbon fiber reinforced plastic (CFRP) as the main material for forming the main body” means that the main body is formed of only carbon fiber reinforced plastic (CFRP), and additionally, a member formed of other materials. A configuration in which (for example, an inner peripheral tube or a coating material) is provided, or a configuration in which another material is added to the carbon fiber reinforced plastic material itself for forming the main body portion by mixing or the like is also included. The centrifuge may be a horizontal type in which the bowl rotates about a horizontal axis, or may be a vertical type in which the bowl rotates about a vertical axis.
(2) As a preferred example, the feed tube may be configured such that a flow path through which the processing liquid flows and a flow path through which a cleaning liquid and / or a chemical liquid flow are formed separately from the flow path through which the processing liquid flows. .

  According to the present invention, in the centrifugal separator that supplies the processing liquid through the feed tube, the main material forming the main body portion of the feed tube is carbon fiber reinforced plastic (CFRP). Is high, the amplitude of the tip is small with respect to the excitation force, and the damping property is excellent with respect to the excitation force. It is possible to prevent the feed tube from being broken in both of the separation operation and the process of lowering the rotation speed of the bowl when the operation is stopped.

  Further, as a preferred modification of the feed tube, if the flow path through which the processing liquid flows and the flow path through which the cleaning liquid and / or the chemical liquid flow are formed separately from the flow path through which the processing liquid flows, the cleaning liquid and the chemical liquid The feed tube can also be applied to a type of centrifugal separator that requires a functional fluid such as the above.

1 is a longitudinal sectional view of a centrifugal separator according to a first preferred embodiment of the present invention. It is a perspective view which shows the feed tube of the said centrifuge. It is a figure which shows typically the frequency and vibration displacement of a centrifuge. It is a figure which shows typically the frequency and vibration displacement of a centrifuge. It is a figure for demonstrating the attenuation | damping characteristic of a feed tube. It is a figure for demonstrating the modification of the said feed tube. It is the schematic for demonstrating the basic composition of a centrifuge.

  Hereinafter, a centrifugal separator according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the technical scope of the present invention is not construed as being limited by the embodiments described below.

(First embodiment)
As shown in FIG. 1, the decanter 1 of the present embodiment includes a casing 2 in which a solid phase outlet 20 and a liquid phase outlet 21 are formed on the lower surface side, a bowl 3 disposed in the casing, and a bowl 3. The screw conveyor 4 which conveys the centrifuged solid phase, and the pipe-shaped feed tube 5 which is a supply nozzle for supplying the process liquid to be centrifuged into the bowl 3 are provided. Both axes of the bowl 3 are supported by a bearing mechanism 22 such as a bearing disposed outside the casing 2. Further, the screw conveyor 4 is supported at both shafts by a bearing mechanism 23 such as a conveyor bearing. Reference numeral 24 denotes a partition wall that partitions the space in the casing 2.

  When the power of the main motor 25, which is a drive mechanism, is transmitted to the pulley 25b on the bowl 3 side via the rotating belt 25a, the bowl 3 rotates, and further, the gear box 26 and the spline shaft 26a, which are differential speed generators. Rotational power is transmitted to the screw conveyor 4 through this, whereby the bowl 3 and the screw conveyor 4 rotate with a relative differential speed. Although it can be appropriately adjusted depending on the type and concentration of the treatment liquid, as an example of normal operation, the bowl 3 is rotated at a predetermined number of rotations selected within a range of 500 to 8000 rpm, and 0.5 to Centrifugation is performed by rotating the screw conveyor 4 with a differential speed of 50 rpm.

  A motor called a back drive motor 27 is connected to the gear box 26 via a rotating belt 27a and a pulley 27b. The back drive motor 27 is for applying a brake so that the screw conveyor 4 rotates slower than the bowl 3. The regenerative power generated in the back drive motor 27 by applying the brake can be supplied to the main motor 25. However, the back drive motor 27 is not necessarily provided.

  In the bowl 3, a conical portion 31 is formed on one end side of a cylindrical body portion, and a disk-like member called a front hub 32 is provided on the other end side. The body portion of the bowl 3 forms a pool (liquid reservoir) portion of the processing liquid supplied into the bowl 3. On the other hand, the conical portion 31 forms a beach portion where the solid phase conveyed by the screw conveyor 4 is separated from the liquid phase, and a solid phase discharge port 33 is provided at an end thereof. The front hub 32 is provided with a liquid phase discharge port 34 through which the liquid phase overflows and is discharged. The liquid phase discharge port 34 is a circular opening hole that penetrates the front hub 32.

  On the outer peripheral surface of the screw conveyor 4, screw blades 41 for conveying the solid phase are provided in a spiral shape. Further, a supply hole 42 is provided on the outer peripheral surface of the screw conveyor 4. The supply hole 42 communicates with a liquid supply chamber 43 formed inside the tip side of the screw conveyor 4.

  The feed tube 5 is approached or inserted into the liquid supply chamber 43 so as not to contact the rotating bowl 3 and the screw conveyor 4. In other words, the screw conveyor 4 is disposed so as to extend into the screw conveyor 4 along the rotation center axis. In the liquid supply chamber 43, an upright wall 44 is provided along the circumferential direction as a liquid barrier to prevent the supplied processing liquid from flowing backward. The clearance between the upper end of the upright wall 44 and the outer peripheral surface of the feed tube 5 is greatly illustrated for the convenience of drawing, but is actually a slight gap. As an example, it is set to 1 to 20 mm. On the other hand, a pipe from liquid supply means (not shown) such as a pump is connected to the proximal end side of the feed tube 5. The processing liquid sent by the liquid feeding means is discharged into the liquid supply chamber 43 from the tip of the feed tube 5, and further, the processing liquid supplied into the liquid supply chamber 43 has a centrifugal force of the rotating screw conveyor 4. By the action, it is discharged from the supply hole 42 and supplied into the bowl 3.

  The main components of the decanter 1 described above are supported by being installed on a gantry 28 made of, for example, metal. The feed tube 5 is fixedly supported at the base end side by a support member 29 extending from the gantry 28. That is, the feed tube 5 is installed in the decanter 1 with the base end side being cantilevered. Therefore, for example, vibration generated in the decanter 1 by the rotation of the bowl 3 and the screw conveyor 4 acts as an excitation force on the feed tube 5 that is cantilevered with the support member 29 as a fulcrum.

  As shown in FIG. 2, the feed tube 5 includes a pipe-shaped main body 51 that is inserted into the screw conveyor 4. The length of the main body 51 is set to a length selected from the range of 300 to 3000 mm, for example, according to the specifications of the decanter 1 and the like. The base end portion 52 of the feed tube 5 is provided with a flange portion 53 for connecting a pipe from a liquid feeding means such as a pump. Carbon fiber reinforced plastic (CFRP) is adopted as the main material forming the main body 51 of the feed tube 5. That is, the main body 51 may be preferably formed of only carbon fiber reinforced plastic, or a member formed of another material may be added. As an example, in order to improve the corrosion resistance and wear resistance of the processing liquid flowing in the main body 51, an inner peripheral tube and / or an outer peripheral tube formed of a material such as metal or resin may be arranged, or the inner periphery The surface and / or the outer peripheral surface may be coated. Moreover, you may add another material to the carbon fiber reinforced plastic material itself which shape | molds the main-body part 51 by mixing. The base end portion 52 may also be manufactured integrally with the main body portion 51 using carbon fiber reinforced plastic (CFRP). In this example, the base end portion 52 is made of a metal that is relatively easy to process. A preferred example of the metal forming the base end portion 52 is a metal such as stainless steel.

  The main body 51 made of carbon fiber reinforced plastic (CFRP) is preferably rolled up with multiple layers of carbon fiber to improve strength. As an example, carbon fiber may be wound and molded by a filament winding method, or a carbon fiber reinforced plastic prepreg may be wound and molded. In this case, the resin may be thermoplastic. Alternatively, resin and carbon fiber may be mixed and injection molded or extruded.

  Here, in order to help the understanding of the present invention, the main cause of the breakage of the feed tube 5 will be described with reference to FIGS. FIG. 3 schematically shows the frequency and vibration displacement that appear during operation of the decanter 1. The frequency can be obtained by a calculation formula (frequency [Hz] = rotational speed [rpm] / 60 [sec]). The frequency when the rotation speed of the bowl 3 is 4000 rpm is 67 Hz. The cause of the vibration generated in the decanter 1 is largely due to the rotation of the bowl 3 and the screw conveyor 4 (as described above, the screw conveyor 4 rotates at substantially the same speed as the bowl 3). As schematically shown in FIG. 3A, the amplitude resulting from the rotation of the bowl 3 and the screw conveyor 4 appears in the vicinity of a frequency of 67 Hz. As an example of the design specification of the decanter 1, each component (a bowl, a screw conveyor, etc.) is designed and manufactured so that the vibration displacement is within about 50 to 80 μm. In such a design specification, even with a conventional stainless steel feed tube, since the vibration acting as an excitation force is small, there is no vibration at the tip or the vibration width is small, and the feed tube 5 is not broken. Absent.

  However, in the process of increasing the number of rotations of the bowl 3 at the start of operation, the frequency corresponding to the number of rotations of the bowl 3 may overlap with the natural frequency of the stainless steel feed tube, which is schematically shown in FIG. As shown in the figure, when the tip of the feed tube swings greatly at the resonance point and the swing width exceeds the clearance with the standing wall 44 of the screw conveyor 4, it collides with the standing wall 44 and the strength of the feed tube can withstand the collision. It breaks when not. Such a phenomenon can also occur in the process of lowering the rotation speed of the bowl 3 at the end of the operation.

  Further, when the decanter 1 is used for a long period of time, unbalance may occur due to uneven wear of the bowl 3 and the screw conveyor 4. Unbalance may also occur due to clogging or unevenness of the solid phase in the bowl 3. When such an imbalance occurs, the vibration displacement that appears during operation of the decanter 1 increases. As schematically shown in FIG. 4A, the vibration displacement at a frequency of 67 Hz, which was actually about 70 μm during the separation operation in the design specification, may increase to, for example, 100 to 150 μm. When the vibration displacement is increased due to the unbalance in this way, as shown schematically in FIG. 4B, the deflection width of the tip of the feed tube at the resonance point is further increased.

  From the above, in the conventional stainless steel feed tube, even if measures are taken at the design stage such as increasing the thickness and increasing the strength, additional vibration displacement due to the occurrence of imbalance, etc. It may not be possible to cope with uncertain factors that arise. Further, since the clearance with the standing wall 44 is determined by design, there is a limit to increasing the strength by increasing the thickness of stainless steel.

  On the other hand, the feed tube 5 of this embodiment has high strength by using carbon fiber reinforced plastic (CFRP) as a main material for forming the main body 51 extending to the liquid supply chamber 43 of the screw conveyor 4. The process of increasing the number of rotations of the bowl 3 at the start of operation because the amplitude of the tip is small with respect to the excitation force caused by resonance and the like, and the attenuation is high with respect to the excitation force caused by resonance and the like It is possible to prevent the feed tube from being broken in the process of lowering the rotation speed of the bowl when the operation is stopped. Due to the advantageous characteristics of the feed tube 5, it is possible to prevent the feed tube from being broken even during the separation operation in which the treatment liquid is separated into solid and liquid.

That is, a plurality of feed tubes 5 made of carbon fiber reinforced plastic were actually manufactured and tested for confirmation . As an example, one having a strength six times that of a stainless steel feed tube manufactured in the same shape could be designed. Therefore, even if it collides with the standing wall 44 of the screw conveyor 4 at the start of operation, at the time of separation operation, and at the time of operation stop, it is possible to withstand the collision.

  In addition, when the feed tube 5 made of carbon fiber reinforced plastic was actually tested and confirmed, as compared to the stainless steel feed tube manufactured in the same shape as shown in the time-axis response waveform shown in FIG. The result that the amplitude of the front-end | tip part was small when an excitation force was given to the base end side was obtained. Therefore, even if resonance occurs, there is a high probability that collision with the standing wall 44 of the screw conveyor 4 can be avoided, and even if there is a collision, the impact is small. Further, since the amplitude of the tip portion is small with respect to the excitation force, for example, even if the vibration displacement of the decanter 1 increases due to the above-described imbalance, the collision with the standing wall 44 of the screw conveyor 4 is avoided. be able to.

  Furthermore, since the feed tube 5 made of carbon fiber reinforced plastic has high damping properties, even if resonance occurs and the tip portion is shaken, the shake converges at an early stage. Therefore, the number of times of collision with the standing wall 44 of the screw conveyor 4 can be reduced to the extent that the feed tube is broken.

  As a modification of the feed tube 5, a flow path for supplying a cleaning liquid and / or a chemical liquid may be formed outside the central processing liquid flow path. FIG. 6 shows an example. That is, as shown in FIG. 6A, a double-pipe structure in which a flow path 54 for the treatment liquid is formed at the center and a plurality of flow paths 55 for the cleaning liquid and / or the chemical liquid is formed around the flow path 54 can be formed. When supplying both the cleaning liquid and the chemical liquid, one of the plurality of flow paths 55 is assigned to the cleaning liquid, and the rest is assigned to the chemical liquid. As a modification, as shown in FIG. 6B, a configuration may be adopted in which the flow channel 54 and the flow channel 55 are assigned to four flow channels that are partitioned at intervals of 90 degrees in the circumferential direction. Furthermore, as a modification, as shown in FIG. 6C, a structure may be adopted in which a plurality of channels 55 having small diameters are formed on the outer periphery of the channel 54 of the central processing liquid. That is, the configuration can be changed as appropriate. As the cleaning liquid, for example, cleaning water for cleaning the inside of the decanter 1 can be supplied. Further, as the chemical solution, a flocculant such as a polymer flocculant or an inorganic flocculant can be supplied. Even with this configuration, it is possible to obtain the same effect as that of the feed tube 5 described above.

(Second Embodiment)
The feed tube 5 according to the present embodiment is configured such that its natural frequency is higher than the frequency corresponding to the rotation speed of the bowl 3 during the separation operation. Other configurations excluding this limitation are the same as those in the first embodiment. As described above, the frequency can be obtained by a value obtained by dividing the number of revolutions by 60 (frequency [Hz] = number of revolutions [rpm] / 60 [sec]). For example, the frequency when the number of revolutions is 4000 rpm is 67 Hz. Become. The natural frequency of the feed tube 5 may be obtained by calculation or simulation from information such as shape and material, or may be obtained by actually manufacturing the feed tube 5 and performing a test.

  As an example, the feed tube 5 having an outer diameter of 36 mm, an inner diameter of 31 mm, a thickness of 2.5 mm, and a length of 760 mm was manufactured, and the natural frequency was analyzed. The natural frequency 89 Hz is more than 20% higher than the frequency 67 Hz. In this example, a 20% increase is considered sufficient. However, it is only necessary that the natural frequency is located on the higher frequency side than the frequency corresponding to the rotation speed of the bowl 3 during the separation operation, and the size of the feed tube 5 is not particularly limited.

  If the natural frequency (89 Hz) is higher than the frequency corresponding to the rotation speed of the bowl 3 during the separation operation, the rotation speed of the bowl 3 is increased to the rotation speed during the separation operation at the start of operation. In the process and the process of lowering the rotation speed of the bowl 3 at the end of the operation, the frequency corresponding to the rotation speed of the bowl 3 does not pass the natural frequency of the feed tube 5. Therefore, it is possible to prevent the feed tube 5 from being broken. Furthermore, since the natural frequency (89 Hz) of the feed tube 5 is 20% or more of the frequency (67 Hz), it is possible to prevent the feed tube 5 from being broken even during the separation operation. Furthermore, even if an increase in vibration displacement due to the occurrence of imbalance occurs, the influence is not exerted.

  Although the present invention has been described in detail with reference to specific embodiments, various substitutions, modifications, changes, etc. in form and detail are defined in the claims. It will be apparent to those skilled in the art that this can be done without departing from the spirit and scope.

1 Decanter 2 Casing 3 Bowl 4 Screw conveyor 5 Feed tube 51 Feed tube body 52 Feed tube base end

Claims (2)

A rotary bowl for solid-liquid separation of the processing liquid by centrifugal force, a rotary screw conveyor for conveying the solid phase separated in the bowl toward the discharge port, and for supplying the processing liquid into the bowl A centrifuge with a non-rotating feed tube,
A centrifugal separator characterized by using carbon fiber reinforced plastic (CFRP) as a main material forming the main body of the feed tube.   The flow path in which the cleaning liquid and / or the chemical liquid flow are formed separately from the flow path in which the processing liquid flows and the flow path in which the processing liquid flows in the feed tube. Centrifugal device.