JP2010149094A - Screw press dehydrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase a solid matter conveying capacity in the former concentration zone and increase a sludge loading rate in the subsequent filtration zone and compression zone with a small model. <P>SOLUTION: A screw press dehydrator includes: an outer cylinder screen formed in a shape of a cylinder; a screw provided with a spiral screw vane on the outer periphery of a tapered shaft, rotatably disposed in the outer cylinder screen, and being approximately brought into contact with the outer cylinder screen at the outer peripheral end surface of the screw vane; a sludge supply port provided on the shaft small-diameter portion side of the screw; a cake outlet provided on the shaft large-diameter portion side of the screw; an outer cylinder provided on the outer periphery of the outer cylinder screen and receiving a filtrate squeezed out from the outer cylinder screen; a drive unit for rotating and driving the screw; and a pump communicating with the sludge supply port and sending sludge under pressure. In the concentration zone formed between the screw and the outer cylinder screen on the sludge supply port side, the spiral screw vane is composed of a plurality of lines of spiral screw vanes. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an improvement of a screw press type dehydrator used as a sludge dehydrator in the sewerage treatment field and the industrial wastewater treatment field.

  Conventionally, this type of screw press type dehydrator is, for example, as disclosed in Non-Patent Document 1, a cylindrical outer cylinder screen fixed in a horizontal shape (a stainless steel wire mesh or punching plate having a different mesh depending on the type of sludge). In the case of sewage sludge, the diameter is 0.5 to 3 mm.), A tapered screw shaft rotating in the outer cylinder screen, screw blades having the same outer diameter at each part integrated with the screw shaft, It consists of a hopper-like sludge supply port provided on one side of the screw, a cake outlet provided on the opposite side, a receiving tray for receiving the filtrate squeezed outward from the outer cylinder screen, a screw drive device, etc. Yes.

  According to this screw press dehydrator, sludge (sludge) conditioned with a polymer flocculant is introduced into an outer cylinder screen via a hopper with a constant flow rate sludge supply pump, and rotated at a very low speed (0.1 to 0.1). 1rpm) screw is transferred from the inlet to the outlet, and the volume between the screw and the outer cylinder screen, where the pitch of the screw blades becomes smaller and thicker on the screw shaft decreases toward the cake outlet, and the sludge is gradually compressed and dewatered. Discharged.

Recently, for example, as disclosed in Non-Patent Document 2, a high-efficiency press-fitting screw press dehydrator is proposed that improves the sludge filling rate in the concentration zone and improves the dewatering performance compared to this screw press dehydrator. Has been.
This high-efficiency press-fitting type screw press dehydrator improves the solid material transport capacity in the concentration zone by rotating the outer cylinder screen of the concentration zone in the direction opposite to the screw shaft rotation direction, and continues to the filtration zone and pressing zone. It is said that the processing capacity can be increased 1.3 times compared with the conventional type by increasing the sludge filling rate in

In this high-efficiency press-fitting type screw press dehydrator, a sludge twisting action and a shearing action are generated, and a large amount of separated liquid is discharged from the screen, thereby increasing the effect of conveying solid matter. Therefore, a high sludge filling rate is obtained in the subsequent filtration and pressing zone.
"Guide to using polymer flocculants" (Tokyo Sewer Service Co., Ltd., issued in March 2002) "Technical Manual for High-Efficiency Press-Filled Screw Press Dehydrator, March 2006" (New Sewerage Technology Promotion Organization, issued in March 2006)

  However, in the high-efficiency press-fitting screw press dehydrator described in Non-Patent Document 2, the structure of the screen rotating unit is added to the conventional screw press dehydrator, so the structure becomes complicated and the drive device for the concentration screen Therefore, there is a problem that the electric control is complicated and the cost is greatly increased.

  The present invention has been made in order to solve such a conventional problem, and its purpose is to improve the solid material transport capacity in the preceding concentration zone in a small model, and in the subsequent filtration zone and compression zone. The object is to provide a screw press dehydrator capable of increasing the sludge filling rate.

  The screw press type dehydrator according to claim 1 is provided with an outer cylinder screen having a cylindrical shape and a spiral screw blade on an outer periphery of a tapered shaft, and is rotatably disposed in the outer cylinder screen. A screw whose outer peripheral end surface is substantially in contact with the outer cylinder screen, a sludge supply port provided on the small-diameter portion side of the screw, a cake outlet provided on the large-diameter portion side of the screw, and the outer cylinder screen An outer cylinder that is provided on the outer periphery and receives the filtrate squeezed from the outer cylinder screen; a drive device that rotationally drives the screw; and a pump that communicates with the sludge supply port and pumps the sludge, and supplies the sludge. In the concentration zone formed between the screw and the outer cylinder screen on the mouth side, the spiral screw blades have a plurality of strips. Characterized in that it is constituted by a screw blade of the spiral.

  The screw press type dehydrator according to claim 2 is provided with an outer cylindrical screen having a vertical cylindrical shape and a spiral screw blade on the outer periphery of a tapered shaft, and is rotatably disposed in the outer cylindrical screen. A screw whose outer peripheral end surface is substantially in contact with the outer cylinder screen, a sludge supply port provided on the small-diameter portion side of the screw, a cake outlet provided on the large-diameter portion side of the screw, and an outer cylinder Provided on the outer periphery of the screen and receiving the filtrate squeezed from the outer screen, a driving device for rotating the screw, a pump connected to the sludge supply port, and pumping the sludge, the sludge supply port side In the concentration zone formed between the screw and the outer cylinder screen, the spiral screw blades are formed by a plurality of spiral screw blades. Characterized in that it is configured Te.

The screw press dehydrator according to claim 3 is the screw press dehydrator according to claim 1 or 2, wherein the spiral screw blade is constituted by two or three spiral screw blades in the concentration zone. It is characterized by.
The screw press type dehydrator according to claim 4 is the screw press type dehydrator according to any one of claims 1 to 3, wherein the inlet sludge moisture content in the concentration zone is 98 to 96.5% (weight ratio). The outlet sludge moisture content of the zone is 93 to 95% (weight ratio).

In the concentration zone, only two or three screw blades are used, and only by driving the same screw shaft without operating the drive device separately, the processing capacity (filtration rate (solid material amount per hour)) is improved. be able to.
In the concentrating zone, the screw blade pitch itself is the same as before, and by simply increasing the number of threads, sludge can be maintained on the blade surface upstream of the direction of travel of the screw blade, so that a high sludge transfer speed can be maintained, improving processing capacity. It can contribute greatly.
In the concentrating zone, frequent stripping of the inner screw of the outer cylinder screw with multiple thread blades increases the exposed capacity of the bare filtration surface, which can drastically reduce the moisture content of the sludge cake using the internal and external pressure difference more effectively. Therefore, even if the screw is installed vertically, the solid matter can be conveyed by the large pitch screw blade, and a large amount of concentrated sludge can be conveyed to the subsequent filtration zone.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a vertical screw press dehydrator 1 according to the present invention.
The screw press type dehydrator 1 according to the present embodiment is provided with an outer cylindrical screen 3 having a vertical cylindrical shape, and screw blades 9 that are spiral and have the same outer shape of each blade on the outer periphery of a tapered shaft 7. A tapered screw 5 that is rotatably disposed in the outer cylinder screen 3 with the small shaft diameter portion 7a at the bottom, a sludge supply port 13 provided on the small shaft diameter portion 7a side of the screw 5, and a large shaft diameter of the screw 5. Cake outlet 15 provided on the part 7b side, outer cylinder 17 provided on the outer periphery of the outer cylinder screen 3 for receiving the filtrate squeezed from the outer cylinder screen 3, a drive device 19 for rotationally driving the screw 5, and sludge supply A pump (not shown) that communicates with the port 13 and pumps sludge is provided.

  For the outer cylinder screen 3, for example, a SUS304 wire mesh or a punching plate is used. And as for the filtration hole, the hole diameter of the concentration zone mentioned later is 1.0-1.5 mm, the hole diameter of a filtration zone is 0.7-1.0 mm, and the hole diameter of a pressing zone is 0.5-0. It is set to 6 mm. In this embodiment, the hole diameter of the concentration zone is 1.2 mm, the hole diameter of the filtration zone is 0.8 mm, and the hole diameter of the pressing zone is 0.5 mm. The length and the diameter of the outer cylinder screen 3 are arbitrary, but in this embodiment, the length of the outer cylinder screen 3 is 660 mm and the diameter of the outer cylinder screen 3 is 200 mm.

The screw 5 is made of, for example, SUS304 material. The shaft 7 of the screw 5 is directed from the sludge input side to the dewatered cake discharge side so that the filter chamber 11 formed between the outer cylinder screen 3 continuously decreases in volume toward the dewatered cake discharge side. The taper is thickened.
The pitch of the screw blades 9 is reduced from the sludge input side toward the dewatered cake discharge side so that the volume of the filter chamber 11 continuously decreases toward the dewatered cake discharge side, similarly to the shaft 7. Is set to The pitch of the screw blades 9 is substantially the same as that in Non-Patent Document 1.

  Further, in the concentration zone formed between the screw 5 and the outer cylinder screen 3 on the sludge supply port 13 side, the screw blade 9 is the second screw at the same pitch as the screw blade 9 in order to improve the processing performance. The blades 9A are formed and are two strips. In addition, the area | region which installs the screw blade | wing 9A is good also as about 1/4 to 2/3 of the whole from the sludge supply port 13. FIG. In the present embodiment, the case of two strips has been described, but three strips may be used. However, if the length is 4 or more, there is a risk of hindering the production.

The outer cylinder screen 3, the screw 5, and the outer cylinder 17 are erected on the pedestal 23 using a watertight mechanism via a receiving portion 25 communicating with the sludge supply port 13. The receiving part 25 has a short cylindrical shape, and the upper side thereof is the lower surface of the outer cylinder 17, and the outer cylinder screen 3 has a watertight seal on the inner surface of the hole whose upper side is opened by a coaxial small-diameter circle. This prevents the sludge in the receiving portion 25 from short-passing to the outer cylinder 17. The screw 5 passes through a hole opened by a coaxial small-diameter circle on the lower side of the receiving portion 25 at the lower end of the shaft 7 through a water-tight seal, and has a lower end portion of the small-diameter portion 7a in the lower part thereof. The space between the outside of the shaft 7 of the screw 5 and the screw blade 9 communicates with the receiving portion 25.
A shaft 27 is attached to the screw 5 so as to pass through the receiving portion 25 from the lower end portion of the small shaft diameter portion 7a of the screw 5 and protrude into the mount 23, and is supported by a bearing (not shown) so as to be rotatable. A sprocket 33 is attached to the shaft 27, and is connected via a chain 35 to a sprocket 39 provided on a drive shaft 37 of a drive device 19 installed on the mount 23. A hollow shaft 31 is attached to the lower end portion of the outer cylinder screen 3 and is connected to a metal fitting 29 for receiving the outer cylinder screen 3, and is coaxially disposed outside the shaft 27 of the screw 5. A sprocket 41 is attached in the vicinity of the lower end of the hollow shaft 31 and is connected to a sprocket 47 provided on a drive shaft 45 of a drive device 43 of the outer cylinder screen 3 installed on the mount 23 via a chain 49. .

A discharge port 21 for discharging the filtrate is provided below the outer cylinder 17. Further, the outer cylinder 17 is provided with a plurality of water spray nozzles 51 in the vertical direction for backwashing the outer cylinder screen 3 when the operation is stopped between the dehydration operation and the dehydration operation. The back washing of the outer cylinder screen 3 is performed by washing the outer cylinder screen 3 with a spray of pressure water when the operation is stopped. At this time, the outer cylinder screen 3 is rotationally driven by a driving device 43 to Wash the whole.
On the upper side of the outer cylinder 17, a cylinder part 53 that covers the terminal end side of the large-diameter part side 7 b of the screw 5 is provided. The cylinder portion 53 is provided with an outlet pressure sensor 55.
In addition, an outlet cone 57 is installed in the end portion of the screw 5 in the cylindrical portion 53. The outlet cone 57 adjusts the discharge amount while pressing the dehydrated cake discharged from the cylindrical portion 53 by the outlet control cylinder 61 installed on the shaft 59 provided at the terminal portion of the screw 5. The outlet control cylinder 61 communicates with a compressed air supply source (not shown) via a compressed air pipe 63.

Around the outlet cone 57, a dewatered sludge storage portion 65 connected to the tube portion 53 is formed, and a rotary cake scraping blade 67 is rotatably arranged. The rotary cake scraping blade 67 is suspended from a donut-shaped rack internal gear 71 rotatably supported on the inner periphery of the dewatered sludge storage portion 65, and a spur gear 73 meshing with the rack internal gear 71 is provided. The provided shaft 75 is attached to the dewatered sludge storage portion 65 via a bearing, and a spur gear 77 is provided on the shaft 75, and the spur gear 77 is provided on a shaft 59 connected to the terminal end of the screw 5. By meshing, the inside of the dewatered sludge container 65 can be rotated in synchronization with the rotation of the screw 5.
The dehydrated sludge storage unit 65 is provided with a cake outlet 15.

  In the screw press type dehydrator 1 according to this embodiment, as shown in FIG. 1, a concentration zone (moisture 98 to 95%), a filtration zone (from the small shaft diameter portion 7 a to the large shaft diameter portion 7 b of the screw 5). 95 to 88%), the filter chamber 11 is formed so as to constitute a compression zone (88 to 75%).

Next, the operation of the vertical screw press dehydrator 1 according to this embodiment will be described.
Aggregated sludge made of solid matter, for example, 2 to 3 mm, flocated by adding a flocculant, is introduced into the outer cylinder screen 3 from the sludge supply port 13 at a pressure of, for example, 30 to 50 Ps from a pump (not shown). The screw 5 is rotated at a low speed (0.08 to 1 rpm) and is conveyed while being dehydrated in a filter chamber 11 formed between the concentrating zone and the outer cylinder screen 3 by screw blades 9 and 9A.

  This mechanism will be described with reference to FIG. The moisture content of the inlet sludge in the concentration zone is 98% to 95% (in other words, the solid concentration is 2% to 5% (weight ratio)), and the sludge introduced into the screw press dehydrator 1 is pressurized. Attaching and depositing on the inner surface of the outer cylinder screen 3 on the flow flowing from the high filter chamber 11 to the space between the outer cylinder 17 and the outer cylinder screen 3 on the outside of the outer cylinder screen 3, the screw blade 9 And 9A, it adheres to the blade surface on the upstream side in the traveling direction of the screw 5 and is conveyed to the subsequent filtration zone. As soon as the screw blades 9 and 9A pass, the outer cylinder screen 3 is exposed, and the water in the filter chamber 11 between the blade pitches flows into the filtration chamber 79 formed between the outer cylinder 17 at once.

  In the transport mechanism of the concentration zone as described above, the surface of the outer cylinder screen 3 is scraped off by the screw blades 9 and the screw blades 9A by providing only two screws in the screw blade 9 with the screw blades 9A added to the concentration zone. Since the screw pitch of each screw blade 9 and screw blade 9A remains the same while proceeding with moisture filtration by doubling the opportunity, the screw blade 9 and screw blade 9A and the outer cylinder screen 3 are contacted at a high speed at a high speed. In addition, more sludge can be supplied later.

Thus, the conveyance efficiency of the sludge (solid matter) adhering to the inner surface of the outer cylinder screen 3 is also increased when the blade surface length on the upstream side in the traveling direction of the screw 5 is doubled by double screwing. The sludge adheres to the blade surface in the same manner as when the concentrating zone is a single screw, and the screw pitch is the same. For this reason, the sludge filling rate in the filtration zone and the compression zone following the concentration zone is increased, and the concentrated sludge is the upper surface of the inner surface of the outer cylinder screen 3 and the blade surface on the upstream side in the traveling direction of the screw 5. In addition, since sludge is mainly solidified and collected, the dewatering performance is finally improved.
Then, the dewatered sludge flows into the dewatered sludge storage 65 while receiving the pressing force by the outlet cone 61 from the compression zone, and is discharged from the cake outlet 15 by the rotary cake scraping blade 67.

In the conventional screw press type dehydrator, for example, as shown in FIG. 3, since there is no screw blade 9A, the cleaning effect by the inner surface of the outer cylinder screen 3 and the screw blade 9 is the screw press type according to this embodiment. It becomes 1/2 of the dehydrator 1 and the filtrate discharge amount is reduced, which is lower than the concentration by the screw press type dehydrator 1 according to this embodiment.
Moreover, the conveyance efficiency of the sludge (solid matter) adhering to the inner surface of the outer cylinder screen 3 is also halved, and the sludge filling rate in the filtration zone and the compression zone following the concentration zone is the screw press type dehydration according to this embodiment. It becomes lower than the machine 1, and finally the dewatering performance will be inferior.

Further, as in the high-efficiency press-fitting screw press dehydrator disclosed in Non-Patent Document 2, a conventional mechanism is provided without forcibly rotating the outer cylinder screen in the concentration zone in the direction opposite to the screw. By the same operation as that of the screw press type dehydrator, it is possible to obtain a sludge (solid matter) conveying efficiency equal to or higher than that of the high-efficiency press-fitting tester screen press dehydrator.
At the time of cleaning regeneration, the driving device 43 is driven to perform cleaning regeneration of the outer cylinder screen 3 in the same manner as a conventional screw press dehydrator.

As described above, according to the present embodiment, without adding a large device or adding electric control, in the concentration zone, only a two-thread screw in which another screw blade 9A is added to the screw blade 9 is used. Therefore, improvement of processing capacity (filtration speed) can be expected.
For this reason, a model lower in rank can obtain a throughput capacity equivalent to that of the conventional model, so that the equipment cost is reduced. Compared to that, the cost increase to the double screw is very small.

Furthermore, if the processing capacity is the same as that of the conventional model, the cake moisture content can be reduced from that of the conventional model.
In the above embodiment, the screw press type dehydrator according to the present invention has been described as a vertical type, but it can also be used as a horizontal type or an inclined type.

It is a lineblock diagram showing the screw press type dehydrator concerning one embodiment of the present invention. It is an expanded sectional view explaining the effect | action of the screw press type dehydrator of FIG. It is an expanded sectional view explaining the effect | action of the conventional screw press type dehydrator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Screw press type dehydrator 3 Outer cylinder screen 5 Screw 7,27 Shaft 7a Shaft small diameter part 7b Shaft large diameter part 9,9A Screw blade 11 Filter chamber 13 Sludge supply port 15 Cake outlet 17 Outer cylinder 19 Drive device

Claims (4)

An outer cylinder screen having a cylindrical shape;
A screw provided on the outer periphery of the tapered shaft, the screw blade is rotatably disposed in the outer cylinder screen, and the outer peripheral end surface of the screw blade is substantially in contact with the outer cylinder screen;
A sludge supply port provided on the small shaft diameter side of the screw;
Cake outlet provided on the shaft large diameter side of the screw;
An outer cylinder that is provided on the outer periphery of the outer cylinder screen and receives the filtrate squeezed from the outer cylinder screen;
A driving device for rotationally driving the screw;
A pump that communicates with the sludge supply port and pumps sludge;
In the concentration zone formed between the screw and the outer cylinder screen on the sludge supply port side, the spiral screw blade is constituted by a plurality of spiral screw blades. Press type dehydrator. An outer cylinder screen having a vertical cylindrical shape;
A screw provided on the outer periphery of the tapered shaft, the screw blade is rotatably disposed in the outer cylinder screen, and the outer peripheral end surface of the screw blade is substantially in contact with the outer cylinder screen;
A sludge supply port provided on the small shaft diameter side of the screw;
Cake outlet provided on the shaft large diameter side of the screw;
An outer cylinder that is provided on the outer periphery of the outer cylinder screen and receives the filtrate squeezed from the outer cylinder screen;
A driving device for rotationally driving the screw;
A pump that communicates with the sludge supply port and pumps sludge;
In the concentration zone formed between the screw and the outer cylinder screen on the sludge supply port side, the spiral screw blade is constituted by a plurality of spiral screw blades. Press type dehydrator. In the screw press type dehydrator according to claim 1 or 2,
The screw press type dehydrator characterized in that the spiral screw blade is constituted by two or three spiral screw blades in the concentration zone. In the screw press type dehydrator according to any one of claims 1 to 3,
Screw press type dehydration characterized in that the inlet sludge moisture content of the concentration zone is 98-96.5% (weight ratio) and the outlet sludge moisture content of the concentration zone is 93-95% (weight ratio). Machine.

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