WO2007032605A1

WO2007032605A1 - Screw type solid-liquid separation appartus

Info

Publication number: WO2007032605A1
Application number: PCT/KR2006/003050
Authority: WO
Inventors: Sang-Chul Byun
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-09-12
Filing date: 2006-08-03
Publication date: 2007-03-22
Anticipated expiration: 2008-03-12
Also published as: KR100672218B1

Abstract

A screw type solid-liquid separation apparatus is disclosed. The separation apparatus of the present invention includes a casing (10), which has a sludge supply part (11) and a solid discharge part (12) respectively at first and second ends thereof, and a water collection tub (14) at a lower position thereof. The separation apparatus further includes a separating means (20), which has stationary rings (21) fastened to support plates (27a) and (27b) such that fine gaps (g) are defined between the stationary rings (21), with a screw insertion space (S) defined through the stationary rings (21). The separation apparatus further includes a screw (30), which is inserted into the screw insertion space (S) and has a spiral blade (32) thereon, and a cleaning means (40), which includes a support member (41) that is fastened to the spiral blade in the axial direction of the screw (30), and cleaning blades (44) that are coupled to the support member (41) such that at least one cleaning blade (44) is placed in each fine gap (g).

Description

SCREW TYPE SOLID-LIQUID SEPARATION APPARTUS

Technical Field

[1] The present invention relates, in general, to screw type solid-liquid separation apparatuses and, more particularly, to a screw type solid-liquid separation apparatus which removes liquid from sewage sludge, suspensions, various kinds of industrial waste, etc. (hereinafter, referred to simply as sludge) generated from a sewage disposal plant, a waste disposal plant, a manure disposal plant or a paper factory.

Background Art

[2] Generally, sewage sludge generated in a sewage disposal plant has a low concentration (99.3 to 99.5 weight % of water content). Typically, such sewage sludge, which has a low concentration, is carried to another place using a transport vehicle to be disposed of in landfill, incinerated, or reused. Here, to reduce the logistics costs of the process of carrying the sludge to another place using the vehicle, it is concentrated and dehydrated before being carried.

[3] To achieve the above purposes, conventional solid-liquid separation apparatuses were disclosed in Japanese Examined Patent Publication No. Heisei. 6-42928, Korean Patent Registration No. 121732 (PCT Publication No. WO93/16867), Japanese Patent Laid-open Publication No. Heisei. 11-33316, and Korean Patent Registration No. 413164.

[4] In the solid-liquid separation apparatus disclosed in Japanese Examined Patent

Publication No. Heisei. 6-42928, rings are arranged in an axial direction at predetermined small intervals and are securely coupled to each other, thus constructing a cylindrical body. Furthermore, a screw, which has spiral blades provided on a screw shaft in an axial direction, is inserted into a space defined in the cylindrical body, thus constructing a sludge carrying screw conveyor. Cleaning blades, which are placed in the respective fine gaps defined between the rings, are provided on the respective spiral blades to return solids that enter the fine gaps to the space defined in the cylindrical body.

[5] The solid-liquid separation apparatus of Korean Patent Registration No. 121732 includes a solid-liquid separation unit, a screw conveyor and a drive means. The solid- liquid separation unit has a plurality of stationary rings, which are arranged in an axial direction, are spaced apart from each other at regular intervals, and are integrally coupled to each other, and movable rings, which are disposed in the respective gaps defined between the stationary rings. The screw conveyor is rotatably disposed inside the stationary rings and the movable rings. The drive means rotates the screw conveyor. The inner diameters of the movable rings are smaller than the outer diameter of the screw conveyor. Furthermore, a protrusion, which is forcibly rotated by the screw conveyor, is provided on the circumferential inner surface of each movable ring.

[6] In the screw type solid-liquid separation apparatus of Japanese Patent Laid-open

Publication No. Heisei. 11-33316, ring-shaped rotary plates are arranged between ring- shaped stationary plates in a circular shape, thus constructing a typical filtration body. An inlet is formed in one end of the filtration body, and an outlet is formed in the other end of the filtration body. Furthermore, a screw is rotatably placed in the filtration body. Thus, sludge, which is supplied through the inlet, is carried to the outlet by rotation of the screw. During this process, liquid separated from the sludge is discharged through gaps between the stationary plates and the rotary plates. The rotary plates are rotatably supported and have gears, which are coupled to the actuator through a gear train, so that the rotary plates are rotated by the actuator. Alternatively, protrusions are provided on the circumferential inner surfaces of the rotary plates so as to be able to contact the screw, so that the rotary plates are rotated depending on the rotation of the screw.

[7] The screw type solid-liquid separation apparatus of Korean Patent Registration No.

413164 includes a separation tank, which has at opposite ends thereof a sludge supply part and a solid discharge part, and a separation means. The separation means has stationary plates which are placed in the separation tank at regular intervals, and movable plates which are disposed between the stationary plates, with fine gaps defined between the stationary plates and the movable plates. The separation apparatus further includes a screw, which is installed in space defined in the separation means, and a movable plate drive means, which is operated in conjunction with the screw. The movable plate drive means includes a cam, which is provided on the screw shaft, a drive plate, which is supported at the center of the upper end thereof on the cam, and connection bars, which are coupled to respective opposite sides of the lower end of the drive plate and are supported by support members provided on the movable plates. Thus, the movable plates are moved along the outline of the cam.

[8] In the case of the solid-liquid separation apparatus disclosed in Japanese Examined

Patent Publication No. Heisei. 6-42928, because the fine gaps are directly formed between the rings constituting the cylindrical body in order to remove liquid through the fine gaps, there is the advantage of reduced volume of the apparatus. However, because the screw conveyor has a structure in which the spiral blades are provided on the screw shaft and in which the cleaning blades, which are provided on the outer edges of the respective spiral blades, are placed in respective fine gaps, the spiral blades are easily damaged, and a lot of time is required to replace the spiral blades with new ones. Therefore, there is a disadvantage in that the maintenance cost is high.

[9] In the solid-liquid separation apparatus of Korean Patent Registration No. 121732, the rotating structure of the movable rings is simple, but, because the solid-liquid separation unit consists of both stationary rings and movable rings, the volume of the separation apparatus is increased, thereby a relatively large space is required. Furthermore, the inner diameter of the movable rings is smaller than the outer diameter of the screw conveyor, and the movable rings are directly rotated by the blade of the screw conveyor. Therefore, due to abrasion between the movable rings and the blade of the screw conveyor, the lifetime of the separation apparatus is reduced. In addition, when a large amount of solids is held in gaps between the stationary rings and the movable rings, the resistance of the movable rings is increased, thus there is a likelihood of damage to the protrusions, which are provided on the circumferential inner surfaces on the movable rings. If the protrusions are damaged, the solid-liquid separation unit must be disassembled in order to be repaired. As a result, a lot of cost and time is required.

[10] The screw type solid-liquid separation apparatus of Japanese Patent Laid-open

Publication No. Heisei. 11-33316 has the filtration body including the stationary plates and the rotary plates, in a structure similar to that of Korean Patent Registration No. 121732. Therefore, the volume of the separation apparatus is increased and thus a large space is required. Furthermore, the structure of the rotary plate drive means, in which the gears are provided on the circumferential outer edges of the rotary plates and are coupled to the actuator through the gear train, is complex. In addition, like the separation apparatus of Korean Patent Registration No. 121732, because the protrusions are provided on the circumferential inner surfaces of the rotary plates so as to be able to contact the screw and are rotated depending on the rotation of the screw, if the protrusions are damaged, the filtration body must be disassembled. This incurs a high cost and requires a lot of time.

[11] The screw type solid-liquid separation apparatus of Korean Patent Registration No.

413164 has an advantage in that, even if solids are held in the fine gaps, the solids are easily removed by the movable plates operated by the movable plate drive means. However, because the separation means consists of the stationary plates and the movable plates, the volume of the separation apparatus is increased, so that a relatively large installation space is required. Furthermore, because the movable plate drive means includes the cam, the drive plate and the connection bars, the structure thereof is complex. As well, if the movable plates are overloaded, movement of the drive plate along the outline of the cam becomes difficult. Therefore, the fine gaps may not be sufficiently cleaned. Disclosure of Invention

Technical Problem [12] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a screw type solid-liquid separation apparatus which is reduced in volume and can satisfactorily clean fine gaps, and in which the structure of a cleaning means is simplified, so that the likelihood of malfunction is reduced, and installation and disassembly thereof can be easily conducted.

Technical Solution

[13] In order to accomplish the above object, the present invention provides a screw type solid-liquid separation apparatus, including: a casing, having a sludge supply part at a first end thereof, a solid discharge part at a second end thereof, and a water collection tub at a lower position thereof; a separating means having a plurality of stationary rings fastened to support plates, which are provided at least at opposite ends of the casing, such that fine gaps are defined between the stationary rings, with a screw insertion space defined through the stationary rings; a screw inserted into the screw insertion space of the separating means, with a spiral blade provided on the screw; and a cleaning means rotated by rotating force of the screw, the cleaning means having a support member fastened to a circumferential outer edge of the spiral blade in an axial direction of the screw, and a plurality of cleaning blades coupled to the support member such that at least one cleaning blade is placed in each fine gap.

Advantageous Effects

[14] In the solid-liquid separation apparatus of the present invention, because fine gaps are directly defined between stationary rings of a separation means and cleaning blades are placed in the respective fine gaps, the volume and size of the separation apparatus are markedly reduced, thus the manufacturing cost thereof is reduced. Furthermore, a cleaning means has a structure such that a support member is provided on an outer edge of a spiral blade of a screw, and the cleaning blades, which are placed in the respective fine gaps, are supported by the support member. Thus, a process of removing solids from the fine gaps can be automatically conducted using only the force of the screw rotating in all of the fine gaps. As such, thanks to the simple structure, the probability of malfunction is reduced. As well, the efficiency of with which liquid is removed is increased compared to the conventional art, which uses movable rings. In addition, abrasion of the cleaning blades is markedly reduced. Even if the cleaning blades are worn by use for a long period, they are easily and rapidly removed and replaced with new ones. Hence, productivity is increased, and maintenance costs are reduced.

Description of Drawings

[15] FIG. 1 is a longitudinal sectional view of a screw type solid-liquid separation apparatus, according to an embodiment of the present invention;

[16] FlG. 2 is a sectional view taken along the line A-A of FlG. 1 ;

[17] FlG. 3 is an exploded perspective view showing critical parts of the screw type solid-liquid separation apparatus of FlG. 1 ;

[18] FIGS. 4 through 7 are views showing the operation of the screw type solid-liquid separation apparatus of FlG. 1 ; and

[19] FIGS. 8 through 10 are views showing a process of removing a cleaning blade of the screw type solid-liquid separation apparatus of FlG. 1.

Best Mode

[20] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[21] FlG. 1 is a longitudinal sectional view of a screw type solid-liquid separation apparatus according to an embodiment of the present invention. FlG. 2 is a sectional view taken along the line A-A of FlG. 1. FlG. 3 is an exploded perspective view showing critical parts of the screw type solid-liquid separation apparatus. The screw type solid-liquid separation apparatus of the present invention includes a casing 10, a separating means 20, a screw 30 and a cleaning means 40.

[22] The casing 10 has a sludge supply part 11 at a first end thereof and has a solid discharge part 12 at a second end thereof. The casing 10 further has casing walls 13a and 13b at front and rear positions thereof, and a water collection tub 14 at a lower position thereof. The casing 10 is placed on a support bed 15.

[23] The separating means 20 includes a plurality of stationary rings 21. Each stationary ring 21 has therein a circular hole 22, which has a diameter such that the stationary ring 21 does not interfere with the rotation of a screw, which will be explained herein later. Four fastening pieces 23 are integrally provided around the outer edge of each stationary ring 21. A support hole 24 is formed through each fastening piece 23. Spacers 25, each having a predetermined thickness, are interposed between the fastening pieces 23, and support bars 26 are inserted through the support holes 24 and the spacers 25, so that fine gaps (g) ranging from 0.2 mm to 1 mm are defined between the stationary rings 21, and a screw insertion space (S) is defined by the circular holes 22 of the stationary rings 21. Opposite ends of the support bars 26 are fastened to support plates 27a and 27b, which are supported on the support bed 15 and are respectively disposed at positions adjacent to the sludge supply part 11 and the solid discharge part 12, using locking nuts 28a and 28b.

[24] The screw 30 includes a screw shaft 31, and a spiral blade 32, which is provided around the circumferential outer surface of the screw shaft 31. The screw 30 is inserted into the screw insertion space (S). First and second ends of the screw shaft 31 are respectively supported by the support plate 27a and the outer wall of the solid discharge part 12. Furthermore, the second end of the screw shaft 31 is coupled to a drive unit 33, which is provided adjacent to the solid discharge part 12. The screw 30 having the above-mentioned construction serves to carry sludge, which is supplied through the sludge supply part 11, to the solid discharge part 12.

[25] Furthermore, a back pressure plate 34 is slidably provided on the second end of the screw shaft 31 which is adjacent to the solid discharge part 12, thus adjusting the pressure at which solids are discharged, thereby adjusting the dehydration rate of the apparatus.

[26] The sludge supply part 11 is provided such that the discharge center thereof is formed around the center of the screw shaft 31. Furthermore, the lower part of the outer wall 16 of the sludge supply part 11 is inclined towards the solid discharge part 12, so that, when flocculated sludge is input into the sludge supply part 11, the flock? is prevented from being damaged, thus increasing separation efficiency. A hole 17 is formed through the outer wall 16, and an openable cover plate 18, which openably closes the hole 17, is provided on the outer wall 16, so as to facilitate interior inspection and the removal of sludge when an excessively large amount of sludge is input.

[27] Meanwhile, the separation means 20 is sectioned at an intermediate position by a sectional plate 29. Based on the sectional plate 29, a portion adjacent to the sludge supply part 11 (the right portion in FIG. 1) is defined as a concentration section, and a portion adjacent to the solid discharge part 12 (the left portion in FIG. 1) is defined as a dehydration section. The spiral blade 32 of the screw 30 is constructed such that the pitch of the part thereof adjacent to the dehydration section is smaller than the pitch of the part thereof adjacent to the concentration section. Thus, during a process of concentrating and dehydrating sludge, 95 weight % of water content of sludge can be controlled.

[28] The cleaning means 40 includes a support member 41, which is provided in an outer edge of the spiral blade 32 in the axial direction of the screw 30, and at least one cleaning blade 44, which is supported by the support members 41 and is placed in each fine gap (g) defined between the stationary rings 21. Thus, the cleaning blades 44 are rotated merely by the rotating force of the screw 30. Each cleaning blade 44 has a thickness less than the size of the fine gap (g), so that water films can be formed between the stationary rings 21 and the opposite surfaces of the cleaning blade 44.

[29] The support member 41 comprises a pair of support bars 42. Notches 43a and 43b are formed in the outer edge of the spiral blade 32 at positions spaced apart from each other by a regular distance. The support bars 42 are inserted into and welded to the notches 43a and 43b, so that the support bars 42 maintain a constant distance therebetween. Each cleaning blade 44 includes a blade body 45, which has locking stops 46a and 46b on opposite ends thereof, so that the locking stops 46a and 46b are hooked to the respective support bars 42. Furthermore, the blade body 45 of each cleaning blade 44 has an inclined edge 47 on an end thereof, that is, on a leading rotation end thereof, so that, when the blade body 45 rotates in the fine gap (g), the inclined edge 47 minimizes the rotating resistance and makes it easy for solids to enter the center space of the stationary rings 21, thus efficiently conducting the cleaning operation.

[30] The blade body 45 has a tool stop notch 48 on the other end thereof, such that when replacement of the cleaning blade 44 is required, it can be conveniently removed.

[31] Meanwhile, two support members 41 may be provided at opposite positions. Alternatively, more than two support members 41 may be provided. As such, in the case that two or more support members 41 are provided, even if the cleaning blades 44 cannot be provided on one support member 41 at some positions of the fine gaps (g) of the stationary rings 21 because the outer edge of the spiral blade 32 interferes with the desired positions of the fine gaps (g), the cleaning blades 44 can be selectively provided on the other support member 41 at positions at which the outer edge of the spiral blade 32 does not interfere with the fine gaps (g). Therefore, the cleaning blades 44 can be provided in all fine gaps (g), and the separation efficiency of the separation apparatus can thus be maximized.

[32] The operation of the separation apparatus of the present invention will be explained herein below.

[33] Sludge, which has been flocculated by previously mixing it with flocculant, is supplied into the sludge supply part 11 provided on the first end of the casing 10, while the screw 30 is rotated by the drive unit 33. The sludge is carried to the solid discharge part 12. As such, while the sludge is carried towards the solid discharge part 12, the sludge is concentrated by the spiral blade 32 of the screw 30 in the screw insertion space (S) and the fine gaps (g) defined between the stationary rings 21. At this time, liquid is dropped into the water collection tub 14 after passing through the fine gaps (g). The liquid collected in the water collection tub 14 is carried to a subsequent processing place. Furthermore, solids are discharged to the solid discharge part 12 in a concentrated state, that is, in a dehydrated state. As a result, the weight of the sludge is reduced.

[34] Furthermore, in the present invention, during the process of removing liquid from the sludge, the number of revolutions of the screw 30 can be adjusted, the fine gaps (g) may be adjusted by changing the thickness of the spacers 25 interposed between the stationary rings 21, and the inclination angle of the separation means 20 can be adjusted. The water content, that is, the concentration of the sludge, can be adjusted through such adjustment. As such, if 75 to 80 weight % of the water content of the sludge is removed, it is convenient to treat the sludge in subsequent processes.

[35] Meanwhile, during the process of removing liquid from the sludge, some solids enter the fine gaps (g) defined between the stationary rings 21. The solids, which enter the fine gaps (g), are removed by the cleaning blades 44, which are provided on the spiral blade 32 of the screw 30 and are rotated along with the screw 30. As such, the fine gaps (g) are automatically cleaned by the cleaning blades 44, and the solids, removed from the fine gaps (g), are returned into the screw insertion space (S).

[36] In the present invention, because the fine gaps (g) are directly defined between the stationary rings 21 of the separation means 20 and the cleaning blades 44 are placed in the respective fine gaps (g), the volume of the separation apparatus is markedly reduced, thus the manufacturing cost thereof is reduced.

[37] As such, while sludge is carried by rotation of the screw shaft 31, the cleaning blades 44, which are supported on the support members 41 provided on the outer edge of the spiral blade 32 in the axial direction of the screw shaft 31, remove solids in all fine gaps (g) (that is, along the entire length of the stationary rings 21) using only the rotating force of the screw 30 (see, FIGS. 4 through 7). Therefore, the efficiency with which liquid is removed is increased compared to the conventional art, which uses movable rings.

[38] Furthermore, while the separation apparatus removes liquid from sludge, water films are formed between the opposite surfaces of the cleaning blades 44, which are placed in the fine gaps (g), and the stationary rings 21, thus acting as water bearings. In addition, because each cleaning blade 44, which is placed in each fine gap (g) between the stationary rings 21, is supported on the support member 41, when friction between one surface of the cleaning blade 44 and the related stationary ring 21 is increased, the cleaning blade 44 moves in a direction in which friction is reduced along the support member 41. As such, the distances between the cleaning blades 44 and the stationary rings 21 can be automatically maintained. Therefore, the present invention reduces abrasion of the elements, thus markedly extending the lifetime of the separation apparatus.

[39] As well, when a cleaning blade 44 is worn by use for a long period in the state in which the separation apparatus is stopped, a tool (T) is inserted into the associated fine gap (g) and is hooked into the tool stop notch 48 and, thereafter, the tool (T) is pulled, as shown in FIGS. 8 through 10. Then, the locking stop 46b of the cleaning blade 44 is removed from the associated support bar 42, and the part of the cleaning blade 44 in which the locking stop 46b is provided protrudes outside the outer edges of the stationary rings 21. Thereafter, a user holds the cleaning blade 44 and removes the locking stop 46a from the associated support bar 42. Thus, the cleaning blade 44 can be easily and rapidly removed and replaced with a new one. The installation of the cleaning blades 44 is conducted in the order opposite to that of the removal thereof. As such, because the installation and replacement of the cleaning blades 44 can be easily conducted, productivity is increased, and the maintenance cost is reduced.

Industrial Applicability

[40] As described above, in the solid-liquid separation apparatus of the present invention, because fine gaps are directly defined between stationary rings of a separation means and cleaning blades are placed in the respective fine gaps, the volume and size of the separation apparatus are markedly reduced, thus the manufacturing cost thereof is reduced. Furthermore, a cleaning means has a structure such that a support member is provided on an outer edge of a spiral blade of a screw, and the cleaning blades, which are placed in the respective fine gaps, are supported by the support member. Thus, a process of removing solids from the fine gaps can be automatically conducted using only the force of the screw rotating in all of the fine gaps. As such, thanks to the simple structure, the probability of malfunction is reduced. As well, the efficiency of with which liquid is removed is increased compared to the conventional art, which uses movable rings. In addition, abrasion of the cleaning blades is markedly reduced. Even if the cleaning blades are worn by use for a long period, they are easily and rapidly removed and replaced with new ones. Hence, productivity is increased, and maintenance costs are reduced.

Claims

[1] A screw type solid-liquid separation apparatus, comprising: a casing, having a sludge supply part at a first end thereof, a solid discharge part at a second end thereof, and a water collection tub at a lower position thereof; separating means comprising a plurality of stationary rings fastened to support plates, which are provided at least at opposite ends of the casing, such that fine gaps are defined between the stationary rings, with a screw insertion space defined through the stationary rings; a screw inserted into the screw insertion space of the separating means, with a spiral blade provided on the screw; and cleaning means rotated by rotating force of the screw, the cleaning means comprising a support member fastened to a circumferential outer edge of the spiral blade in an axial direction of the screw, and a plurality of cleaning blades coupled to the support member such that at least one cleaning blade is placed in each fine gap.

[2] The screw type solid-liquid separation apparatus according to claim 1, wherein the separation means is sectioned at an intermediate position thereof by a sectional plate into a concentration section adjacent to the sludge supply part and a dehydration section adjacent to the solid discharge part, and the spiral blade of the screw is constructed such that a pitch of a part thereof adjacent to the dehydration section is smaller than a pitch of a part thereof adjacent to the concentration section.

[3] The screw type solid-liquid separation apparatus according to claim 1, wherein the sludge supply part is provided such that a discharge center thereof is formed around a center of an end of the screw shaft, a lower part of an outer wall of the sludge supply part is inclined towards the solid discharge part, a hole is formed through the outer wall, and an openable cover plate, which openably closes the hole, is provided on the outer wall.

[4] The screw type solid-liquid separation apparatus according to claim 1, wherein the cleaning means comprises two cleaning means provided at symmetrical positions.

[5] The screw type solid-liquid separation apparatus according to claim 1, the support member of the cleaning means comprising a pair of support bars, which are inserted into notches that are formed in the outer edge of the spiral blade at positions spaced apart from each other by a regular distance, each of the cleaning blades comprising a blade body, which has locking stops on opposite ends thereof, so that the locking stops are hooked to the respective support bars, and the blade body of each cleaning blade having an inclined edge on a leading rotation end thereof.