JP2017131848A - Centrifugal separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a centrifugal separator capable of enhancing conveyance performance, as well as dehydration performance.SOLUTION: A centrifugal separator comprises: a bowl 106A to be rotated about a rotary axis to solid-liquid separate slurry to be treated, into a separated liquid W and a dehydrated cake K by a centrifugal force; a separated liquid discharge port 112A disposed at one end side of the bowl 106A in a rotary axis direction; a dehydrated cake discharge port 113A disposed at the other end side of the bowl in the rotary axis direction; and a screw conveyor 109A to be rotated about the same rotary axis as the bowl to transfer the dehydrated cake K to the dehydrated cake discharge port 113 on an inner peripheral surface of the bowl 106A. The screw conveyor 109A comprises an inner shell 107A extending in the rotary axis direction; and blades 108A helicoidally disposed on an outer periphery of the inner shell, for scraping the dehydrated cake K. The bowl 106A and the inner shell 107A include an enlarged bowl diameter part 211 and an enlarged shell diameter part 201, respectively, with respective diameters gradually enlarged as approaching to the respective other ends. The enlarged bowl diameter part 211 has a smaller taper angle α than the taper angle β of the enlarged shell diameter part 201.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a centrifuge and relates to a technique for improving transportability and dewatering performance.

2. Description of the Related Art Conventionally, there are centrifuges such as a centrifugal dehydrator and a centrifugal concentrator as apparatuses for treating sludge generated in a sewage treatment process, for example.
A centrifugal dehydrator rotates a sludge at a high speed to separate a sludge component and moisture by a specific gravity difference, and dehydrates. For example, there is one described in Patent Document 1.

This is shown in FIG. 2, and the centrifugal dehydrator 100 supports the dehydrating main body 104 disposed on the main structural member 101 with bearings 105a and 105b.
The dewatering main body 104 has a cylindrical straight body-shaped bowl 106 and an inner body 107 disposed inside the bowl 106 concentrically, and the bearing portions 105a and 105b are rotation shafts at both ends of the bowl 106 in the rotational axis direction. Portions 106a and 106b are rotatably supported, and the bowl 106 rotatably supports the rotation shaft portions 107a and 107b at both ends of the inner cylinder 107 in the rotation axis direction. The body 107 is rotatable around the same rotation axis.

The inner cylinder 107 has blades 108 spirally provided around the rotation axis on the outer periphery of the inner cylinder to constitute a screw conveyor 109.
The bowl 106 forms a separation liquid region portion 110 in which a water separation liquid W mainly separated at one end side in the rotation axis direction stays, and the sludge dewatered cake K mainly separated at the other end side in the rotation axis direction. A dehydrated cake region portion 111 to be transferred is formed. A plurality of separation liquid discharge ports 112 are arranged at equal distances from the rotation axis and at predetermined intervals around the rotation axis on the end wall 110a on one end side of the bowl 106 in the rotation axis direction.

  A dam plate (dam plate) 112a is attached to each separation liquid discharge port 112 so as to cover a part of the opening of each separation liquid discharge port. The dam plate 112a adjusts the position of the bowl 106 in the bowl radial direction, thereby setting the weir height at the separation liquid discharge port 112 that is the upper limit water level of the separation liquid W in the bowl 106. A plurality of dewatered cake discharge ports 113 are arranged on the peripheral wall on the other end side in the rotation axis direction of the bowl 106 at radial positions around the rotation axis and at predetermined intervals around the rotation axis.

  The inner cylinder 107 has a diameter-expanded portion in which the outer diameter of the inner cylinder increases in a tapered shape as a portion corresponding to the other end of the bowl 106 approaches the other end of the bowl 106, and dewatering between the inner cylinder 107 and the bowl 106 is performed. The cake region portion 111 becomes narrower as it approaches the other end of the bowl 106, and the bottleneck 106 c between the outer peripheral surface of the other end of the inner drum 107 and the inner peripheral surface of the other end of the bowl 106 is dewatered. The outlet 113 is communicated.

  In the dewatering main body 104, the inner cylinder 107 rotates at a predetermined differential speed with respect to the bowl 106, and the screw conveyor 109 transfers the dewatered cake K toward the other end of the bowl 106 on the inner peripheral surface of the bowl 106. The dehydrated cake K is pushed out from the dehydrated cake region 111 to the dehydrated cake discharge port 113 through the bottleneck 106c.

  The housing 114 disposed so as to cover the dehydration main body 104 is fixed to the main structural member 101, and has a separation liquid discharge port 115 that opens downward at a portion surrounding the separation liquid discharge port 112 of the separation liquid region portion 110. In addition, a dehydrated cake discharge port 116 opening downward is provided at a portion surrounding the dehydrated cake discharge port 113 of the dehydrated cake region 111.

  A hydraulic motor 118 is connected as a differential speed device to the rotating shaft portion 106b on the side of the dehydrated cake region portion 111 supported by the bearing portion 105b and the rotating shaft 107b of the inner cylinder 107 passing through the rotating shaft portion 106b. A drive motor of a drive source and a hydraulic pump (not shown) are connected to the motor.

  The sludge supply pipe 120 is inserted into the inner cylinder 107 through the rotating shaft part 106a on the separation liquid region part 110 side supported by the bearing part 105a, and the tip opening 120a is inserted into the sludge of the inner cylinder 107. It faces the wall surface of the part 121. The chemical supply pipe 122 is inserted into the sludge supply pipe 120, and the tip opening 122 a faces the wall surface of the sludge inlet 121 of the inner trunk 107.

  A plurality of sludge inlets 121a that open toward the inside of the separation liquid region portion 110 are provided on the peripheral wall of the sludge inlet portion 121 of the inner cylinder 107 at radial positions centered on the rotation axis and around the rotation axis. Arranged at intervals.

  In this configuration, the raw sludge S is supplied through the sludge supply pipe 120 to the sludge input section 121 of the inner cylinder 107 that rotates at high speed, and the polymer flocculant C is supplied through the chemical supply pipe 122 to the sludge input section of the inner cylinder 107 that rotates at high speed. The mixed sludge of raw sludge S and polymer flocculant C is fed into the bowl 106 rotating at high speed from the sludge inlet 121a of the sludge inlet 121.

  The mixed sludge including the sludge floc F aggregated inside the bowl 106 is solid-liquid separated into the separated liquid W and the dehydrated cake K by centrifugal force. The screw conveyor 109 having a rotational speed difference (differential speed) with the bowl 106 transfers the dehydrated cake K to the dehydrated cake area 111, and the moisture content of the dehydrated cake K further decreases while moving in the dehydrated cake area 111. It is discharged from the dehydrated cake discharge port 113 into the housing 114 and discharged from the dehydrated cake discharge port 116 to the outside of the machine.

  The separation liquid W that flows over the dam plate 112a from the separation liquid discharge port 112 of the bowl 106 and is discharged to the inside of the housing 114 is subjected to centrifugal force and diffused around the rotation axis, and is discharged from the separation liquid discharge port 115 to the outside of the machine. Is released.

JP 2014-155894 A

  In the centrifugal dehydrator described above, the screw conveyor has a factor that the tendency to co-rotate with the dehydrated cake during the actual load operation causes a decrease in the conveyance performance, such as a decrease in the processing capacity of the centrifuge and a deterioration in the water quality of the separated liquid. Problems may arise. In particular, the dehydrated cake having a low water content has a large frictional force with the blades of the screw conveyor, and the dehydrated cake easily rotates together with the blades. Under the co-rotation event, the feed speed of the dewatered cake in the direction of the rotation axis due to the rotation of the blades is greatly reduced and the dehydrated cake is stagnated in the bowl, and the difference between the actual feed speed and the rated feed speed is large. Become. For this reason, in order to discharge the dehydrated cake, it is necessary to increase the actual feed rate by increasing the rotational speed of the screw conveyor (differential speed with respect to the bowl). However, an increase in the rotational speed of the screw conveyor acts as a factor for stirring the sewage sludge (mixed sludge) during the centrifugal separation, thereby inhibiting the solid-liquid separation and adversely affecting the dewatering performance. Moreover, the increase in the rotational speed of the screw conveyor leads to a decrease in the residence time of sewage sludge in the bowl. This residence time in the bowl is an element that contributes to the dewatering performance, and is a time during which the sewage sludge is subjected to the centrifugal effect in the bowl. The longer the residence time in the bowl, the better the dewatering performance.

  The residence time in the bowl is also affected by the relationship between the volume of the space between the inner peripheral surface of the bowl and the outer peripheral surface of the inner cylinder and the amount of sludge input. The larger the space volume with respect to the amount of sludge input, the longer the residence time in the bowl. Increases the dehydration performance. On the other hand, since the load increases as the moisture content of the dewatered cake decreases, the screw conveyor is required to have a higher shaft strength. In the screw conveyor, the outer diameter of the blade increases as the bowl inner diameter increases, and the inner cylinder outer diameter increases to ensure the required axial strength. As a result, the space volume is reduced.

  The present invention solves the above-described problems, and an object thereof is to provide a centrifuge capable of improving the conveyance performance and the dewatering performance.

  In order to solve the above problems, the centrifuge of the present invention is a centrifuge for solid-liquid separation of sludge to be treated into separated water and dehydrated cake by centrifugal force, and a bowl rotating around a rotation axis, The separated water discharge port provided at one end of the bowl in the direction of the rotation axis, the dewatered cake discharge port provided at the other end of the bowl in the direction of the rotation axis, and the rotation of the bowl around the same rotation axis as the bowl Provided with a screw conveyor that transfers the dewatered cake toward the dewatered cake discharge port on the inner peripheral surface, and the screw conveyor is spirally provided on the outer periphery of the inner cylinder and the inner cylinder extending along the rotation axis. The bowl and the inner cylinder have a bowl expanding part and an inner cylinder expanding part that taper out toward the other end side in the direction of the rotation axis, Make the taper angle smaller in the bowl diameter expansion part than the taper angle. And features.

  The centrifuge of the present invention is characterized in that the bowl and screw conveyor are made of carbon fiber reinforced plastic, and the blade has friction reducing means for preventing co-rotation on the sludge sliding contact surface that contacts the sludge to be treated.

In the centrifugal separator according to the present invention, the inner cylinder forms an inner cylinder straight body portion having the same inner cylinder outer diameter from the inner cylinder one side end portion on the separation liquid discharge port side toward the inner cylinder enlarged diameter portion. It is characterized by that.
In the centrifuge of the present invention, the bowl is characterized in that a bowl straight body portion having the same bowl inner diameter is formed from the one end of the bowl on the separation liquid discharge port side toward the diameter-enlarged portion of the bowl.

  As described above, according to the present invention, the bowl and the inner cylinder have the bowl diameter-expanding portion and the inner cylinder diameter-expanding portion that expand in a tapered shape toward the other end side in the rotation axis direction, By reducing the taper angle of the bowl diameter-enlarged portion with respect to the taper angle of the portion, a decrease in the conveyance performance on the dewatered cake discharge port side of the bowl is suppressed. That is, in the bowl, the outer diameter of the inner cylinder enlarged portion gradually increases toward the other end side, and the space volume between the inner peripheral surface of the bowl enlarged portion and the outer peripheral surface of the inner cylinder enlarged portion becomes larger. By gradually decreasing in the direction, the sewage sludge is consolidated, and the frictional force between the sliding surface of the blade and the dewatering cake increases. However, the closer to the other end of the bowl, the bowl inner diameter of the bowl enlarged portion gradually increases outward in the radial direction to alleviate the decrease in the space volume and suppress the compaction to prevent the sliding contact surface of the blade and the dewatered cake. Reduces frictional force and prevents co-rotation. On the other hand, the closer to the other end, the more the inner diameter of the bowl gradually increases outward in the radial direction, which increases the centrifugal force action on the inner peripheral surface of the bowl, increasing the squeezing force against the dewatered cake due to the centrifugal force and ensuring the necessary dewatering performance. it can. Therefore, it is possible to reinforce the squeezing force due to the increase in centrifugal force while suppressing compaction due to volume reduction, and to realize a reduction in conveyance performance and an improvement in dewatering performance.

  Further, the closer to the other end of the bowl, the inner diameter of the bowl enlarged portion gradually increases outward in the radial direction, thereby separating the inner peripheral surface of the bowl from the outer peripheral surface of the inner cylindrical enlarged portion. The distance can be set to a size that allows the dewatered cake to be easily discharged while ensuring a predetermined dewatering effect.

  In addition, the bowl, inner body and blades are made of carbon fiber reinforced plastic, while increasing the degree of freedom of blade shape processing while ensuring sufficient strength and rigidity while achieving weight reduction, and the sludge sliding contact surface of the blades Friction reducing means such as buffing can be easily applied.

Sectional drawing which shows the centrifuge in embodiment of this invention Sectional view showing a conventional centrifuge

Embodiments of the present invention will be described with reference to the drawings. In FIG. 1, components having the same functions as those described above with reference to FIG.
In the centrifuge 100A of the present embodiment, the bowl 106A is provided with rotation shafts 106a and 106b provided at both ends in the direction of the rotation axis so that the bearings 105a and 105b support the rotation shafts 106a and 106b. The bowl 106A has a separation liquid discharge port 112A on one end side of the bowl 106A in the direction of the axis of rotation, and the other end side of the sludge. A dewatering cake discharge port 113A is provided, and the dewatering cake region portion 111 side of the inner peripheral surface of the bowl has a bowl expanding portion 211 whose diameter increases in a tapered shape toward the other end side of the bowl 106A in the rotation axis direction. The separation liquid region 110 side forms a bowl straight body 212 having the same bowl inner diameter from the one end of the bowl on the separation liquid discharge port 112 </ b> A side toward the bowl enlarged diameter portion 211. The bowl diameter-enlarged portion 211 has a taper angle α.

  The screw conveyor 109A has an inner cylinder 107A extending along the rotational axis direction and a blade 108A spirally provided on the outer periphery of the inner cylinder to scrape the dehydrated cake. The inner cylinder 107A has an inner cylinder diameter-enlarging portion 201 whose diameter increases toward the other end side of the bowl 106A in the direction of the rotation axis in the direction of the axis of rotation, and the separation liquid region section 110 side is the separation liquid. An inner cylinder straight body 202 having the same outer diameter is formed from one end of the inner cylinder on the discharge port 112 </ b> A side toward the inner cylinder enlarged diameter part 201. The inner cylinder enlarged portion 201 has a taper angle β, the taper angle α of the bowl enlarged portion 211 is smaller than the taper angle β of the inner cylinder enlarged portion 201, and the inner peripheral surface of the bowl and the outer peripheral surface of the inner cylinder Is a minimum gap on the other end side of the inner cylinder enlarged diameter portion 201. The bowl 106A has a bowl maximum inner diameter portion 211a of the bowl enlarged diameter portion 211 on the other end side in the rotation axis direction, and a bowl reduced diameter portion 211b in which the bowl inner diameter gradually decreases on the other end side from the bowl maximum inner diameter portion 211a. The gap between the bowl reduced diameter portion 211b and the end of the inner cylinder enlarged diameter portion 201 communicates with the dehydrated cake discharge port 113A.

  The inner cylinder 107A and the blade 108A of the bowl 106A and the screw conveyor 109A are made of carbon fiber reinforced plastic, and the blade 108A indicates that the sludge to be treated co-rotates on the sludge sliding contact surface 301 in contact with the sludge to be treated. Friction reducing means to prevent is provided. As friction reducing means, the sludge sliding contact surface 301 is buffed to reduce the friction coefficient, a coating layer is formed on the sludge sliding contact surface 301, or a lubricant layer such as a water film or an oil film is formed. It is also possible to do.

  With this configuration, the raw sludge S is supplied through the sludge supply pipe 120 to the sludge input section 121 of the inner cylinder 107A that rotates at high speed, and the polymer flocculant C is supplied at high speed through the chemical supply pipe 122 and the sludge input section of the inner cylinder 107A that rotates at high speed. The mixed sludge of raw sludge S and polymer flocculant C is fed into the bowl 106 rotating at high speed from the sludge inlet 121a of the sludge inlet 121.

  The mixed sludge including the sludge floc F aggregated inside the bowl 106A is separated into solid and liquid by centrifugal force into the separated liquid W and the dehydrated cake K. The dehydrated cake K is scraped to the dehydrated cake area by the rotation of the screw conveyor 109A. The dehydrated cake K is discharged from the dehydrated cake discharge port 113A through the bowl maximum inner diameter portion 211a and the bowl reduced diameter portion 211b.

  In the transport of the dewatered cake K, the bowl 106A and the inner cylinder 107A have a bowl enlarged portion 211 and an inner cylinder enlarged portion 201 that increase in diameter toward the other end side in the direction of the rotation axis, Since the taper angle α of the bowl enlarged portion 211 is smaller than the taper angle β of the diameter portion 201, the outer diameter of the inner trunk enlarged portion 201 gradually increases toward the other end side inside the bowl 106A. The space volume between the inner peripheral surface of the enlarged diameter portion 211 and the outer peripheral surface of the inner trunk enlarged diameter portion 201 is gradually reduced in the radial direction. As the space volume gradually decreases, the sewage sludge to be treated is consolidated, and the frictional force between the sludge sliding contact surface 301 of the blade 108A and the dewatered cake K increases.

  However, the closer to the other end of the bowl 106A, the bowl inner diameter of the bowl enlarged portion 211 gradually increases outward in the radial direction to alleviate the reduction in the space volume, suppress the consolidation, and prevent the sludge sliding contact surface 301 of the blade 108A. And the friction force between the dehydrated cake K and the co-rotation are prevented.

  On the other hand, the closer to the other end, the more the inner diameter of the bowl gradually increases outward in the radial direction, which increases the centrifugal force action on the inner peripheral surface side of the bowl. It can be secured. Therefore, the compaction due to the decrease in volume is suppressed and the reduction in the conveyance performance at the other end of the bowl 106A is suppressed, while the squeezing force due to the increase in centrifugal force is strengthened, and the reduction in the conveyance performance and the improvement in the dewatering performance are realized. it can.

  Further, the closer to the other end side of the bowl 106A, the bowl inner diameter of the bowl enlarged diameter portion 211 gradually increases outward in the radial direction, so that the inner peripheral surface of the bowl and the outer peripheral surface of the inner cylinder on the other end side of the inner cylindrical enlarged diameter portion 201 are increased. And the clearance between the bowl maximum diameter portion 211a and the bowl reduced diameter portion 211b and the end portion of the inner body enlarged diameter portion 201 while ensuring a predetermined dewatering effect. It can be set to a size that can be easily discharged.

100A Centrifugal dehydrator 101 Main structural member 102 Installation floor surface 103 Anti-vibration rubber 104 Dehydrating body part 105a, 105b Bearing part 106A Bowl 106a, 106b Rotating shaft part 106c Bottleneck 107A Inner cylinder 107a, 107b Rotating shaft part 108A Blade 109A Screw conveyor 110 Separation liquid region portion 110a End wall 111 Dehydrated cake region portion 112A Separation liquid discharge port 112a Dam plate 112b Saddle 113A Dehydration cake discharge port 114 Housing 114a Cover member 115 Separation liquid discharge port 116 Dehydration cake discharge port 118 Hydraulic motor 120 Sludge supply Pipe 120a Tip opening 121 Sludge inlet 121a Sludge inlet 122 Drug supply pipe 122a Tip opening 201 Inner cylinder enlarged diameter part 202 Inner cylinder straight trunk part 211 Bowl enlarged diameter part 211a Bowl maximum inner diameter part 211b Bowl reduced diameter 212 bowl straight body 301 sludge sliding surface C polymer flocculant S raw sludge W separated liquid K dehydrated cake alpha, beta taper angle

Claims (4)

Centrifugal separator that separates sludge to be treated into separated water and dehydrated cake by centrifugal force, a bowl rotating around the rotation axis, and a separated water discharge port provided at one end of the bowl in the direction of the rotation axis And a dewatering cake discharge port provided on the other end side of the bowl in the direction of the rotation axis, and rotating around the same rotation axis as the bowl to transfer the dewatering cake on the inner peripheral surface of the bowl toward the dewatering cake discharge port A screw conveyor
The screw conveyor has an inner cylinder extending along the rotation axis direction, and a blade provided spirally on the outer periphery of the inner cylinder to scrape the dehydrated cake, and the bowl and the inner cylinder are located on the other end side in the rotation axis direction. Centrifugal separation characterized in that it has a bowl enlarged portion and an inner barrel enlarged portion that are tapered toward the inner diameter, and the bowl enlarged portion has a smaller taper angle than the taper angle of the inner barrel enlarged portion Machine.   2. The centrifugal separator according to claim 1, wherein the bowl and the screw conveyor are made of carbon fiber reinforced plastic, and the blade has friction reducing means for preventing co-rotation on the sludge sliding contact surface contacting the sludge to be treated.   2. The inner cylinder forms an inner cylinder straight body portion having an inner cylinder outer diameter of the same diameter from an end portion on one side of the inner cylinder on the side of the separated liquid discharge port toward an inner cylinder enlarged diameter portion. Or the centrifuge according to 2;   The centrifuge according to claim 1 or 2, wherein the bowl forms a straight bowl portion of the bowl having the same inner diameter from the one end of the bowl on the side of the separation liquid discharge port toward the enlarged diameter portion of the bowl. Separator.

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