JP2013000661A - Centrifugal separator, and centrifugal separation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently agitate and mix a flocculant supplied to a solid obtained by solid-liquid separation from a matter to be treated and to effectively reduce water content in the solid.SOLUTION: In a centrifugal separator, a screw conveyor 2 which is rotated and driven coaxially with a rotary bowl 1 at a speed different from that of the rotary bowl 1 is provided inside the rotary bowl 1 which is rotated and driven around an axial line O. When a matter to be treated P supplied from a matter to be treated supply port 4A opened at the screw shaft of the screw conveyor 2 is subjected to solid-liquid separation by centrifugal force of the rotary bowl 1 and separated solid is transported by the screw conveyor 2 to one end side in an axial line O direction and is discharged, a protruded wall part 2D protruded to an outer peripheral side is formed over a whole periphery at one end side in an axial line O direction of the screw shaft and a screw blade is provided at least between the protruded wall part 2D and the matter to be treated supply port 4A and further a flocculant supply port 8A for supplying the flocculant L to the solid is provided between the protruded wall part 2D and the matter to be treated supply port 4A in the axial line O direction.

Description

  The present invention relates to a centrifuge equipped with a screw conveyor that is driven to rotate coaxially with a differential speed inside a rotating bowl that is driven to rotate about an axis, and a centrifugal separation method using the centrifuge. .

  As such a centrifugal separator and a centrifugal separation method, for example, in Patent Documents 1 and 2, a rotating cylinder (rotating bowl) composed of a conical inclined part and a cylindrical part is disposed concentrically within the rotating cylinder. Using a decanter-type centrifuge equipped with a screw conveyor that rotates at different rotational speeds, a processed product in which a polymer flocculant is added in advance or a polymer flocculant is added in the cylindrical region of the rotating cylinder It has been proposed to further reduce the moisture content of the solid content (dehydrated sludge) by supplying an inorganic flocculant to the sludge as described above in the inclined region of the rotating cylinder.

Japanese Patent No. 2540198 Japanese Patent Publication No. 6-41000

  However, these centrifugal separators and centrifugal separation methods described in Patent Documents 1 and 2 are dry-drying liquids that are separated by solid-liquid separation and dehydrated as the solid content is conveyed in a direction in which the outer diameter decreases in the inclined portion region of the rotating cylinder. A beach portion is formed, and the flocculant supplied in the inclined portion region is mixed with the solid content by stirring accompanying the conveyance of the solid content by the screw of the screw conveyor, and the solid content and the agglomeration are mixed. It is difficult to effectively reduce the moisture content of the solid content by sufficiently mixing the agent.

  Patent Document 1 also proposes that a stirring blade is attached to the inner cylinder (screw shaft) of the screw conveyor in the inclined portion region to mix the solid content and the flocculant. The rotation speed relative to the minute is just the difference between the rotating cylinder and the screw conveyor when transporting the solid content, and it is also difficult to sufficiently reduce the water content by sufficiently stirring the solid content and the flocculant. It is.

  The present invention has been made under such a background, and the flocculant supplied to the solid content separated into solid and liquid from the processed product supplied in the rotating bowl is sufficiently stirred with this solid content. An object of the present invention is to provide a centrifugal separator and a centrifugal separation method capable of effectively reducing the water content of the discharged solid content by mixing.

  In order to solve the above-mentioned problems and achieve such an object, the centrifugal separator of the present invention is driven to rotate coaxially with a differential speed from the rotating bowl inside the rotating bowl that is driven to rotate about the axis. The processed material supplied from the processed material supply port that opens to the screw shaft of the screw conveyor is solid-liquid separated by the centrifugal force of the rotating bowl, and the separated solid content is separated by the screw conveyor. A centrifugal separator that conveys and discharges to one end side in the axial direction, and a convex wall portion that protrudes radially outward with respect to the axis is formed over the entire circumference on one end side in the axial direction of the screw shaft. In addition, a screw blade is provided at least between the convex wall portion and the processed material supply port, and the convex wall portion is arranged in the axial direction. Between the treated feed opening, characterized in that the coagulant supply port for supplying a flocculant to the solids is provided.

  Further, the centrifugal separation method of the present invention is the above-described centrifugal separator according to the present invention, wherein the processed product supplied from the processed product supply port is solid-liquid separated by the centrifugal force of the rotating bowl, and the separated solid content is It is conveyed to the axial direction one end side by a screw conveyor, the flocculant is supplied to the solid content from the flocculant supply port, and the solid content and the flocculant are stirred by the convex wall portion. To do.

  Thus, the centrifuge in which the convex wall part which protrudes to a radial direction outer peripheral side is formed in the screw shaft in the said axial direction one end side where the solid content isolate | separated from the processed material is conveyed over the perimeter. In the centrifugal separation method using the centrifuge, since the solid flow path between the inner peripheral surface of the rotating bowl is narrowed by the convex wall portion, the conveyed solid content stays in front of the convex wall portion. Thus, the moisture content is reduced by the compaction, but when the solid content is thus compacted, the narrowed flow path between the convex wall portion and the inner peripheral surface of the rotating bowl when the solid content is compacted. When it is further transported from one end to the other end, a stirring action occurs on the solid content.

  Therefore, by providing a flocculant supply port between the convex wall portion and the processed product supply port just before reaching the convex wall portion and supplying the flocculant to the solid content, the solid content stirring action by the convex wall portion This flocculant can be thoroughly mixed with the solids. Moreover, mixing time can be ensured because solid content stays in front of the convex wall portion. Furthermore, the solid content subjected to the stirring action by the convex wall part is one in which solid-liquid separation has progressed due to the centrifugal force of the rotating bowl, and the moisture content is further reduced by the compaction by the convex wall part described above. Therefore, by sufficiently stirring and mixing the flocculant supplied to such a solid content with the solid content, this solid content can be more reliably and effectively agglomerated to further increase the water content in the discharged solid content. Can be reduced.

  As described above, according to the present invention, it is possible to more effectively reduce the moisture content of the solid content that is separated from the processed material and discharged. Therefore, for example, when the treated material is sewage sludge, it is possible to improve the fuel efficiency of the incineration equipment when incinerating the discharged dewatered sludge, while reducing the amount of dewatered sludge when transported by landfill disposal. Therefore, it is possible to increase the efficiency of sludge removal and extend the life of landfill sites.

It is a sectional side view which shows the outline of one Embodiment of the centrifuge of this invention. It is AA expanded sectional drawing in FIG.

  1 and 2 are schematic views showing an embodiment of the centrifuge of the present invention. Note that the following description of the embodiment is merely an exemplification, and is not intended to limit the present invention, its application, or its use. In the present embodiment, the rotating bowl 1 has a cylindrical portion 1A centered on the axis O, and is connected to one end side (left side in FIG. 1) of the cylindrical portion 1A in the axis O direction. A conical inclined portion 1B centering on an axis O with a small diameter, and an annular end plate portion 1C perpendicular to the axis O closing the other end side (right side in FIG. 1) of the cylindrical portion 1A in the axis O direction; A cylindrical bowl shaft portion 1F extending from the inner peripheral edge of the end plate portion 1C to the other end side in the direction of the axis O is integrally formed. Such a rotating bowl 1 is accommodated in the casing C so that the axis O is horizontal, and is supported rotatably around the axis O via a bearing (not shown). A bowl rotation driving means (not shown) is also provided. By being connected to the bowl shaft portion 1F extended to the outside of the casing C, it can be rotated around the axis O in one direction at a high speed.

  Inside the rotating bowl 1, a screw conveyor 2 is accommodated around the axis O. The screw conveyor 2 includes a screw shaft and a screw blade (not shown). The screw shaft is inserted into the inner peripheral portion of the bowl shaft portion 1F of the rotating bowl 1 so as to be rotatable relative to the bowl shaft portion 1F. A hollow outer cylindrical shape that is connected to one end side in the axis O direction of the conveyor shaft portion 2A and has a constant outer diameter that is slightly smaller than the inner diameter of the cylindrical portion 1A of the rotating bowl 1 The straight body portion 2B and the cone portion 2C having a conical shape that is continuously provided on one end side in the axis O direction of the straight body portion 2B and gradually decreases in outer diameter toward the one end side. Among these, the screw blades are provided on the outer circumferences of the straight body portion 2B and the cone portion 2C.

  Such a screw conveyor 2 is accommodated in the rotating bowl 1 so that the straight body portion 2B is located on the inner circumference of the cylindrical portion 1A of the rotating bowl 1 and the cone portion 2C is located on the inner circumference of the inclined portion 1B. As in the case of the rotating bowl 1, it is supported so as to be rotatable around the axis O via a bearing (not shown) or the like, and is rotated around the axis O with a differential speed in the same direction as the rotating bowl 1 by a conveyor rotation driving means (not shown). It is possible.

  Here, the outer diameter of the cone portion 2 </ b> C is made slightly smaller so that a radial interval with respect to the axis O is provided between the inner periphery of the inclined portion 1 </ b> B of the rotating bowl 1, and this interval is further reduced. It is made smaller than the space | interval between the cylindrical part 1A inner periphery and the straight body part 2B outer periphery. Accordingly, the outer diameter of the cone portion 2C is made larger than the outer diameter of the straight barrel portion 2B at the other end in the axis O direction. In the meantime, the convex wall portion 2D that faces the other end side and projects radially outward with respect to the axis O is formed so as to be continuous over the entire circumference of the straight body portion 2B. In the present embodiment, the convex wall portion 2D protrudes to the outer peripheral side in the radial direction perpendicular to the axis O.

  The outer diameters of the screw blades provided on the outer circumferences of the straight body portion 2B and the cone portion 2C are smaller than the gap between the cylindrical portion 1A inner periphery and the inclined portion 1B inner periphery of the rotating bowl 1. It is said that it can be opened. The pitch of the screw blades is such that the pitch at the cone portion 2C is smaller than the pitch at the straight body portion 2B. By reducing the pitch, the moving distance of the processed material in the direction of the axis O is extended, and the separation time can be secured. Furthermore, the inclination angle with respect to the axis O of the conical surface formed by the outer peripheral surface of the cone portion 2C is made equal to or larger than the inclination angle with respect to the axis O of the conical surface formed by the inner peripheral surface of the inclined portion 1B of the rotating bowl 1, and accordingly the outer periphery of the cone portion 2C. The distance between the surface and the inner peripheral surface of the inclined portion 1B is constant or gradually increased toward one end side in the axis O direction.

  The hollow portion of the straight body portion 2B is divided by a partition wall 5 into a flocculant supply chamber 3 on the other end side in the axis O direction and a processed material supply chamber 4 on one end side. Here, in this partition wall 5, a circular through hole 5 </ b> A having an inner diameter substantially equal to the inner peripheral portion of the conveyor shaft portion 2 </ b> A of the screw conveyor 2 is formed around the axis O.

  Further, a circular processed product supply pipe 6 having an outer diameter slightly smaller than the inner diameter of the inner peripheral portion and the through hole 5A is provided in the processed product supply chamber 4 from the inner peripheral portion of the conveyor shaft portion 2A through the through hole 5A. However, it is fixed to the rotating screw conveyor 2 in a non-rotating manner and is inserted along the axis O, and an opening on one end side thereof is opened in the workpiece supply chamber 4. Further, from the processed product supply chamber 4 to the outer peripheral surface of the straight body portion 2B, processed product supply ports 4A penetrating in the radial direction with respect to the axis O are formed in one or a plurality of locations in the circumferential direction.

  Furthermore, a flocculant supply pipe 7 is inserted into the processed product supply pipe 6. The flocculant supply pipe 7 is a circular pipe whose inner and outer diameters are sufficiently smaller than the processed product supply pipe 6. In this embodiment, one such flocculant supply pipe 7 is a bottom surface in the processed product supply pipe 6. The other end side from the other end side in the direction of the axis O is inserted to the position of the flocculant supply chamber 3 along the portion, and the bottom surface portion is joined and fixed by welding or the like.

  In addition, at one end portion of the flocculant supply pipe 7 positioned in the flocculant supply chamber 3 in the direction of the axis O, the opening of the circular pipe facing the one end side is closed, and the bottom surface portion of the processed product supply pipe 6 An opening is formed in the side surface facing the. On the other hand, an opening is also formed in the bottom surface of the processed product supply pipe 6 facing the opening of the flocculant supply pipe 7, and these openings are separated from the inside of the processed product supply pipe 6 by a cover 7A or the like. As a result, a flocculant supply pipe opening 7B is formed in which one end of the flocculant supply pipe 7 opens into the flocculant supply chamber 3.

  Further, the flocculant supply chamber 3 is a space surrounded by the inner wall (inner peripheral surface) of the hollow portion of the straight body portion 2B and the partition wall 5, and is spaced apart from the outer peripheral surface of the straight body portion 2B with an axis. The cross section perpendicular to O is formed in a circular shape. In the through hole 5A of the partition wall 5 constituting the flocculant supply chamber 3, the processed material supply pipe 6 is inserted so that the flocculant supply pipe opening 7B is positioned in the flocculant supply chamber 3. . In addition, the inner wall of the hollow portion of the straight body portion 2B constituting the flocculant supply chamber 3 has one or a plurality of locations (for example, 4 to 8 locations) so as to avoid the position of the processed product supply port 4A in the circumferential direction. In this embodiment, as shown in FIG. 2, the coagulant supply holes 3A are formed so as to penetrate through the outer peripheral surface of the straight body portion 2B at six locations at equal intervals in the circumferential direction.

  Further, the screw conveyor 2 is formed with a flocculant supply path 8 in the straight body portion 2B that communicates with the flocculant supply chamber 3 through the flocculant supply hole 3A and extends to one end side in the axis O direction. . The flocculant supply path 8 forms a flocculant supply port 8A that opens in the outer peripheral direction of the axis O between the convex wall portion 2D of the screw conveyor 2 in the axis O direction and the processed product supply port 4A. ing.

  Here, in the present embodiment, a groove 8B having the other end side in the direction of the axis O communicating with the flocculant supply hole 3A and extending to one end parallel to the axis O is provided on the outer peripheral surface of the straight body portion 2B. The same number of holes 3A as the number of the holes 3A are formed, and the recessed grooves 8B extend in the direction of the axis O to the front of the convex wall portion 2D while avoiding the workpiece supply port 4A in the circumferential direction. Further, on the outer peripheral surface of the straight body portion 2B, a long plate-like sealing member 8C having a cross-sectional arc having a radius substantially equal to the outer peripheral surface of the straight body portion 2B is provided except for one end portion in the axis O direction of the concave groove 8B. It is joined so as to close the outer peripheral side opening, and the concave groove 8B portion closed by the sealing member 8C is used as the flocculant supply path 8 and opens to the outer peripheral surface of the straight body portion 2B without being closed. One end portion is a flocculant supply port 8A.

  In addition, at one end side in the axis O direction of the rotating bowl 1, the solid content separated from the processed material P and conveyed to the one end side by the screw conveyor 2 passes through the gap between the inclined portion 1B and the cone portion 2C. The solid content discharge port 1 </ b> D is provided, and is opened to the processed product discharge chamber D on one end side in the axis O direction of the casing C. On the other hand, in the present embodiment, the end plate portion 1C on the other end side in the axis O direction of the rotating bowl 1 is separated from the processed material P by solid-liquid separation and opposite to the conveyance to the one end side of the solid content in the axis O direction and the like. A liquid discharge path 1E for the liquid pushed out to the end side is formed, and is opened to the liquid discharge chamber E on the other end side of the casing C in the axis O direction. The liquid discharge path 1E may be formed in the conveyor shaft portion 2A of the screw conveyor 2.

  Next, an embodiment of the centrifugal separation method of the present invention in which sludge such as sewage sludge is solid-liquid separated as the treated product P by the thus configured centrifugal separator will be described. In the present embodiment, the processed product P in which the polymer flocculant and a part of the inorganic flocculant as necessary are mixed in such sludge is supplied to the processed product supply chamber 4 through the processed product supply pipe 6. Further, it is supplied from the processed product supply port 4A to a space between the rotary bowl 1 and the screw conveyor 2 that rotate at a high speed with a differential speed.

  The processed material P thus supplied to the space between the rotating bowl 1 and the screw conveyor 2 is solid-liquid separated by the centrifugal force of the rotating bowl 1, and the separated solid content is one end in the axis O direction by the screw blades of the screw conveyor 2. Conveyed to the side. On the other hand, the liquid component separated from the processed material P is moved to the other end side in the direction of the axis O so as to be pushed out by the solid component, and discharged from the liquid discharge channel 1E.

  Here, on the one end side of the screw conveyor 2 in the direction of the axis O, the outer wall of the cone portion 2C is made larger than the outer diameter of the straight body portion 2B, so that a convex wall that protrudes radially outward with respect to the axis O. 2D is formed over the entire circumference of the straight body portion 2B, and on one end side of the convex wall portion 2D, the solid flow passage is narrowed on the radially outer peripheral side of the space. On the near side (the other end side in the direction of the axis O) of the convex wall portion 2D, the solid content flow path is lowered toward the inner peripheral side in the radial direction with respect to the axis O.

  Therefore, the solid content conveyed to one end side of the rotating bowl 1 stays in front of the convex wall portion 2D, and is consolidated and further separated by the solid content continuously conveyed, thereby reducing its moisture content. In addition, the solid content staying in front of the convex wall portion 2D flows into the radially inner peripheral side where the solid content flow path is lowered to produce a stirring action. Here, this stirring action is due to the solid content thus transported to one end side in the direction of the axis O flowing into the radial inner peripheral side of the flow path and being dispersed. Stirring by the rotation of the screw blades of the screw conveyor 2 for conveying the solid content at high speed, for example, stirring by the stirring blades attached to the screw conveyor 2, etc. is significant.

  Moreover, the solid content flow path formed between the outer periphery of the cone portion 2C and the inner periphery of the inclined portion 1B on the one end side relative to the convex wall portion 2D flows into the solid content flow path thus consolidated. Since the solid content flow path is narrowed, a stirring action also occurs when the solid content passes between the outer periphery of the convex wall portion 2D and the inner periphery of the rotating bowl 1. Furthermore, since the solid content flow path between the outer periphery of the cone portion 2C and the inner periphery of the inclined portion 1B extends toward the radially inner periphery as it goes toward one end, its cross-sectional area gradually decreases. Again, the solids are consolidated and further separated.

  And in the centrifuge of the said structure, the coagulant supply port 8A is opened between this convex wall part 2D and the said processed material supply port 4A, and in the centrifugation method of this embodiment, processed material P As a coagulant L from the coagulant supply port 8A as a coagulant L (a part of the inorganic coagulant is previously added to the treated product P). If mixed, the remaining inorganic flocculant is supplied.

  That is, the coagulant L supplied to the coagulant supply pipe 7 inserted into the processed product supply pipe 6 flows into the coagulant supply chamber 3 in the screw conveyor 2 from the coagulant supply pipe opening 7B, and the screw conveyor 2 Is pressed to the outer peripheral side in the radial direction with respect to the axis O by the centrifugal force caused by the rotation of, and flows into the coagulant supply path 8 from the coagulant supply hole 3A. Further, the coagulant L flowing into the coagulant supply path 8 in this way passes through the coagulant supply path 8 in the direction of the axis O by the pressing force of the coagulant L continuously supplied from the coagulant supply pipe 7 to the coagulant supply chamber 3. It is pushed out to one end side and supplied from the flocculant supply port 8A to the space serving as a solid content flow path.

  Therefore, the flocculant L supplied in this way is the stirring action of the solid content before the convex wall portion 2D and the stirring action when the solid content passes between the outer periphery of the convex wall portion 2D and the inner periphery of the rotating bowl 1. And are sufficiently mixed with the solid content, thereby effectively promoting the aggregation of the solid content and further reducing the water content. Thus, according to the centrifuge of the above configuration and the centrifuge method using the centrifuge, the solid content is compressed by the convex wall portion 2D of the straight barrel portion 2B and the stirring action of the flocculant L is performed. It becomes possible to greatly reduce the moisture content of the solid content separated from the product P by solid-liquid separation. Moreover, since aggregation of solid content is effectively promoted in this way, the amount of the coagulant L used for reducing the solid content to a predetermined moisture content can be reduced.

  For this reason, when the treated product P is sludge such as the sewage sludge described above, when the dewatered sludge, which is a solid content discharged from the centrifuge, is incinerated, the water content of the dewatered sludge is low. Fuel consumption can be improved by reducing fuel consumption in the incineration facility. In addition, even when the dewatered sludge discharged in this way is disposed of in landfill, the amount of dewatered sludge can be reduced, so that more dewatered sludge can be carried out at a time when it is transported to the landfill site. It is possible to extend the life until the disposal site is completely reclaimed.

  On the other hand, in the centrifuge of the present embodiment, the screw is provided to open the flocculant supply port 8A between the convex wall portion 2D of the screw conveyor 2 and the processed product supply port 4A in the direction of the axis O as described above. A flocculant supply path 8 extending in the direction of the axis O is formed in the conveyor 2 itself so as to open the flocculant supply port 8A, thereby preventing damage to the centrifuge and complication of the apparatus structure, and smoothing. And the effective centrifugation process of the processed material P can be aimed at.

  That is, in the centrifuge that conveys the solid content separated from the processed material P to one end in the direction of the axis O of the rotation of the rotating bowl 1 or the screw conveyor 2 as in this embodiment, the other end in the direction of the axis O The processed product supply pipe 6 and the flocculant supply pipe 7 are inserted from the other end side, and the processed product supply port 4A is opened on the outer peripheral surface of the straight barrel portion 2B on the other end side. In the case where the flocculant supply port 8A is opened between the convex wall portion 2D on the one end side, for example, the flocculant supply chamber 3 is placed closer to the one end side in the axis O direction than the processed product supply chamber 4 contrary to the present embodiment. The flocculant supply pipe 7 is extended along the axis O to the flocculant supply chamber 3 through the through hole 5A of the partition wall 5 and communicated with the outer periphery of the straight barrel portion 2B. It is also conceivable to directly open the flocculant supply port 8A on the surface.

  However, in such a centrifuge, since the length of the flocculant supply pipe 7 becomes long, the structure becomes complicated, and the flocculant supply pipe 7 having a smaller diameter than the processed product supply pipe 6 is used. Is difficult to support straight along the axis O, and the flocculant supply pipe 7 may come into contact with the through hole 5A of the partition wall 5 due to vibrations of the rotating bowl 1 and the screw conveyor 2 rotating at high speed, and may be broken in some cases. There is. In particular, when the flocculant supply pipe 7 becomes longer, the natural frequency thereof becomes lower, so that there is a possibility that the contact with the vibration due to the rotation of the rotating bowl 1 or the screw conveyor 2 is likely to occur.

  However, with respect to such a centrifuge, in the present embodiment, as described above, the flocculant supply path 8 for supplying the flocculant L from the other end side in the axis O direction to the one end side is formed on the screw conveyor 2 itself. Thus, the flocculant supply port 8A can be opened between the convex wall 2D on one end side and the processed product supply port 4A without making the flocculant supply pipe 7 longer than necessary. For this reason, there is no fear of contact between the coagulant supply pipe 7 and the through hole 5A due to resonance or the like, and it is possible to prevent the coagulant supply pipe 7 from being damaged such as breakage, and to simplify the structure of the apparatus. However, it is possible to reliably supply the flocculant L to the solid content between the convex wall portion 2D and the processed product supply port 4A, and thus the stable, effective and smooth processed product P can be obtained over a long period of time. Centrifugation can be performed.

  In order to form the flocculant supply path 8 in the screw conveyor 2 in this way, for example, a long hole extending in the direction of the axis O is formed in the peripheral wall portion of the straight body portion 2B, and the other end communicates with the flocculant supply chamber 3. It is also possible to open one end of the straight body portion 2B on the outer peripheral surface. In such a case, it is necessary to drill the long hole from the other end surface of the straight body portion 2B to the space between the convex wall portion 2D and the workpiece supply port 4A.

  On the other hand, in the present embodiment, the groove 8B is formed in the axis O direction on the outer peripheral surface of the straight body 2B of the screw conveyor 2, and the other end side of the groove 8B is connected to the flocculant supply chamber 3 as the flocculant. While communicating with the supply hole 3A, the outer peripheral side of the concave groove 8B is closed with a sealing member 8C except for one end in the direction of the axis O, so that the one end is a flocculant supply port 8A. 8 is formed. For this reason, compared with the case where the above long holes are drilled, formation of the flocculant supply path 8 is easy, and time, labor, and cost can be reduced.

  Note that the screw blades of the screw conveyor 2 may have a structure in which a spiral blade is directly attached to the outer periphery of the straight body portion 2B or cone portion 2C of the screw shaft, and a plurality of attachment members such as brackets are provided on the screw shaft. You may use the ribbon screw structure which attaches a spiral blade | wing via an attachment member.

  Furthermore, in the present embodiment, the inclined portion 1B of the rotating bowl 1 is formed into a conical shape whose inner and outer diameters gradually decrease toward one end side and is configured integrally with the cylindrical portion 1A, and the cone portion 2C of the screw conveyor 2 is formed. In addition, the outer diameter gradually decreases toward the one end side in the axis O direction and is formed into a conical shape with the straight body portion 2B. The inclined portion 1B and the cone portion 2C are formed on the inner peripheral surface of the inclined portion 1B. And the cone part 2C outer peripheral surface may be configured so as to tend toward the axis O side without going to the outer peripheral side at least toward the one end side in the axis O direction. A horizontal portion parallel to the axis O may be provided in the middle of the inclination approaching the side, or the inclination angle with respect to the axis O may be changed. Further, the inclined portion 1B and the cone portion 2C may be attached to the cylindrical portion 1A and the straight body portion 2B so as to be divided. Furthermore, the separated solid content is caused by the conveying force of the screw blades in the straight body portion 2B of the screw conveyor 2 or the centrifugal head pressure acting on the solid content that is in a compacted state before the convex wall portion 2D. When it is possible to discharge from the discharge port 1D, the screw blades on the outer periphery of the cone portion 2C can be omitted.

  Furthermore, in this embodiment, the concave groove 8B has a “U” cross section as shown in FIG. 2, and the flocculant supply path 8 covered with the sealing member 8C has a substantially square cross section. However, the concave groove 8B may be formed in a semicircular cross section, a U shape, a V shape, or the like, and the outer peripheral side thereof may be covered with the sealing member 8C. Further, instead of forming the concave groove 8B, or in combination with the concave groove 8B, a long plate-shaped seal having a “U” shape, a semicircular shape, a U shape, a V shape, or the like is used. The member 8C is joined so as to extend in the direction of the axis O with a space between the outer peripheral surface of the straight body portion 2B and the concave groove 8B, and the opening on the other end side in the axis O direction is closed and the other end portion is closed. The flocculant supply hole 3 </ b> A may be communicated with the flocculant supply hole 8 </ b> A to form the flocculant supply path 8 having the opening on one end side as the flocculant supply port 8 </ b> A.

DESCRIPTION OF SYMBOLS 1 Rotating bowl 1A Cylindrical part 1B Inclined part 1C End plate part 2 Screw conveyor 2A Conveyor shaft part 2B Straight trunk part 2C Cone part 2D Convex wall supply part 3 Coagulant supply chamber 4 Processed substance supply chamber 4A Processed substance supply port 5 Bulkhead 6 Process Material supply pipe 7 flocculant supply pipe 8 flocculant supply path 8A flocculant supply port 8B concave groove 8C sealing member O axis of rotation of rotating bowl 1 and screw conveyor 2 P processed material L flocculant

Claims (2)

  A screw conveyor that is driven to rotate coaxially with a speed difference from the rotating bowl is provided inside the rotating bowl that is driven to rotate around the axis, and the process supplied from the workpiece supply port that opens to the screw shaft of the screw conveyor. A centrifugal separator that separates solids and liquids by centrifugal force of the rotating bowl and conveys the separated solids to one end side in the axial direction by the screw conveyor and discharges the solid content, and the axial direction of the screw shaft On one end side, a convex wall portion protruding radially outward with respect to the axis is formed over the entire circumference, and a screw blade is provided at least between the convex wall portion and the processed material supply port. A flocculant supply port for supplying the flocculant to the solid content is provided between the convex wall portion and the processed product supply port in the axial direction. Centrifuge, characterized in that they are.   The centrifugal separator according to claim 1, wherein the processed product supplied from the processed product supply port is subjected to solid-liquid separation by centrifugal force of the rotating bowl, and the separated solid content is one end in the axial direction by the screw conveyor. A centrifugal separation method characterized by feeding the flocculant to the solid content from the flocculant supply port and stirring the solid content and the flocculant by the convex wall portion.

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