JP2005028296A - Belt type thickening machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt type thickening machine, which prevents clogging of its endless belt, and improves the dehydration efficiency. <P>SOLUTION: This invention relates to the belt type thickening machine having a mesh type rotatable endless belt 10 gravity-filtering sludge. A scraper 31 is provided on a sending track of the sludge and inclines obliquely upward from an upstream side in the sending direction of the sludge toward the downstream side. A lower end 31a of the upstream side of the scraper 31 is formed to be sharpened in the shape of a knife, and line-contacts transversely with un upper surface of the endless belt 10. A counter base 40 receiving the endless belt 10 from the lower side is provided below the lower end 31a of the upstream side of the scraper 31. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a belt type concentrator used for concentration of surplus sludge (mixed raw sludge, digested sludge, OD surplus sludge) in a sewage treatment plant, for example.

  Conventionally, in this type of belt-type concentrator, a mesh-like endless belt is stretched between both rollers disposed at the upstream end where the sludge to be concentrated is introduced and the downstream end where the sludge to be concentrated is discharged. Some have the configuration described above.

  According to this, as shown in FIG. 11, the concentration target sludge 72 put on the endless belt 71 from the upstream end is gravity filtered while being transported from the upstream side to the downstream side by the rotation of the endless belt 71. Then, it discharges | emits from a downstream end part (for example, refer patent document 1).

  However, in the belt-type concentrator as described above, during gravity filtration, the lower part of the concentration target sludge 72 tends to be dehydrated before the upper part, so the interval between the solid particles in the lower part of the concentration target sludge 72 is narrowed. The consolidated layer A having a smaller space ratio than the upper part is formed in the lower part of the concentration target sludge 72, and the portion remaining above the consolidated layer A becomes the free water layer B, and the upper part of the concentrated sludge 72 (free water layer B). This causes a phenomenon that the dehydration is inhibited by the consolidation layer A. Due to such a phenomenon, it has been difficult to improve the dehydration efficiency.

  On the other hand, as another conventional belt-type concentrator, as shown in FIG. 12, a rod-shaped resistor 76 having a triangular cross section is provided in a gravity filtration portion that gravity filters sludge 72 with a filter cloth 75. There is something.

  According to this, the sludge 72 conveyed from the upstream side to the downstream side by the filter cloth 75 is blocked by the resistor 76 and the moving speed is lowered, thereby improving the dewatering efficiency by the filter cloth 75 ( For example, see Patent Document 2).

Further, a cleaning nozzle (not shown) is provided on the return track of the filter cloth 75, and the filter cloth is cleaned by spraying cleaning water onto the filter cloth 75 from the cleaning nozzle.
However, in the conventional type shown in FIG. 12, since the lower end surface 76 a on the upstream side of the resistor 76 is in surface contact with the upper surface of the filter cloth 75, the sludge 72 is located on the lower end surface 76 a on the upstream side of the resistor 76. And the upper surface of the filter cloth 75, the filter cloth 75 is likely to be clogged by the infiltrated sludge 72. In particular, if the filter cloth 75 bends downward on the lower side of the resistor 76, a large amount of sludge 72 intrudes into the triangular space portion 77 between the resistor 76 and the filter cloth 75 and becomes clogged. There's a problem.

Further, when the supply of the sludge 72 is stopped and the filter cloth 75 is rotated and the washing water is sprayed from the washing nozzle onto the filter cloth 75 to wash the filter cloth 75, the sludge 72 is upstream of the resistor 76. However, the filter cloth 75 cannot be sufficiently washed.
JP 2002-326006 A JP 2000-93712 A

  An object of the present invention is to provide a belt type concentrator capable of preventing clogging of an endless belt and improving dewatering efficiency, and further capable of sufficiently washing the endless belt.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a belt type concentrator having a mesh-like rotatable endless belt for gravity filtering the sludge to be concentrated, and a scraper disposed on the transport track of the sludge to be concentrated. Provided, and the scraper is inclined obliquely upward from the upstream side to the downstream side in the sludge conveying direction, and the upstream lower end of the scraper is formed in a blade shape in the width direction on the upper surface of the endless belt. It is in line contact.

  According to this, the concentration object sludge supplied on the rotating endless belt is gravity filtered while being transported from the upstream side to the downstream side on the transport track by the endless belt. In such gravity filtration, the sludge to be concentrated is peeled upward from the endless belt by the scraper in the process of being transported from the upstream side to the downstream side, and when getting over the scraper, the upper part of the sludge to be concentrated is from the lower consolidated layer. Also precedes. As a result, when the sludge to be concentrated falls from the scraper onto the endless belt, the sludge to be concentrated enters the top and bottom of the sludge to enter the bottom of the consolidated layer, and the consolidated layer is divided or concentrated. Since the sludge is changed from the lower part to the upper part, the inhibition of dewatering of the sludge to be concentrated by the compaction layer is reduced on the downstream side of the scraper, and the dewatering efficiency is improved.

Moreover, since the upper surface of the endless belt is renewed by separating the sludge to be concentrated upward from the endless belt by the scraper, the dewatering efficiency is further improved.
Furthermore, the lower end on the upstream side of the scraper is formed in a blade shape, and is in line contact with the upper surface of the endless belt, not surface contact. For this reason, it can prevent that the sludge to be concentrated enters between the upstream lower end of the scraper and the upper surface of the endless belt, and the endless belt is less likely to be clogged.

In the second invention, a receiving member for receiving the endless belt from the lower side is provided below the lower end on the upstream side of the scraper.
According to this, it is possible to prevent the scraper from excessively pushing the endless belt downward, while the upstream lower end of the scraper is reliably in line contact with the upper surface of the endless belt.

  In the third aspect of the invention, the scraper is configured to be switchable between a retracted position where the scraper retracts above the endless belt and a peeling position where the upstream lower end contacts the upper surface of the endless belt.

  According to this, when dewatering and concentrating the sludge to be concentrated, the scraper is switched to the peeling position. In addition, after the dehydration concentration is finished, when the supply of the sludge to be concentrated is stopped and the endless belt is rotated and the cleaning water is sprayed onto the endless belt for cleaning, the scraper is switched to the retracted position. As a result, the scraper retreats above the endless belt at the time of cleaning, so that the concentration target sludge does not remain at the lower end on the upstream side of the scraper, and thus the endless belt is sufficiently cleaned.

  Moreover, in this 4th invention, a pair of partition plates for preventing the sludge to be concentrated from spilling from the endless belt to both outer sides are provided, and the scraper is inserted between the pair of partition plates. is there.

  According to this, since the concentration object sludge conveyed by the endless belt is partitioned by the pair of partition plates, it does not fall down from the endless belt to both outer sides. In addition, the concentration target sludge is likely to stay in the portion surrounded by the scraper and the partition plate, thereby increasing the residence time of the concentration target sludge in the surrounded portion, and the concentration target sludge in the surrounded portion is from the upstream side. Since it is squeezed and dehydrated by the sludge to be concentrated that is being conveyed, the dewatering efficiency is improved even in the enclosed portion.

  As described above, according to the first aspect of the present invention, when the sludge to be concentrated gets over the scraper while being gravity filtered, the sludge to be concentrated enters the lower part of the consolidation layer, and the sludge to be concentrated enters and goes down. The layer is divided or converted from the lower part of the sludge to be concentrated to the upper part. For this reason, on the downstream side of the scraper, the inhibition of dewatering of the sludge to be concentrated by the consolidation layer is reduced, and the dewatering efficiency is improved.

Moreover, since the upper surface of the endless belt is renewed by separating the sludge to be concentrated upward from the endless belt by the scraper, the dewatering efficiency is further improved.
Furthermore, the lower end on the upstream side of the scraper is formed in a blade shape, and is in line contact with the upper surface of the endless belt, not surface contact. For this reason, it can prevent that the sludge to be concentrated enters between the upstream lower end of the scraper and the upper surface of the endless belt, and the endless belt is less likely to be clogged.

  Further, according to the second aspect of the present invention, it is possible to prevent the scraper from excessively pushing the endless belt downward, while the upstream lower end of the scraper is reliably in line contact with the upper surface of the endless belt.

  Furthermore, according to the third aspect of the invention, during cleaning, the scraper is retracted above the endless belt, so that the sludge to be concentrated does not remain at the lower end on the upstream side of the scraper forever, and therefore the endless belt is sufficiently cleaned. The

  In addition, according to the fourth aspect of the present invention, the sludge to be concentrated conveyed by the endless belt is partitioned by the pair of partition plates, so that it does not spill from the endless belt toward both outer sides. In addition, since the residence time of the sludge to be concentrated in the portion surrounded by the scraper and the partition plate becomes long, the sludge to be concentrated in the surrounded portion is compressed and dehydrated by the sludge to be concentrated conveyed from the upstream side, The dewatering efficiency is also improved in the enclosed part.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1 and FIG. 2, 1 is gravity-filtered and dehydrated and concentrated on the concentration target sludge 3 supplied from the supply unit 2 (supply chute, etc.) on the upstream side (start end side), and downstream (end side) ) Is a belt type concentrator that discharges from the discharge unit 4 (discharge chute, etc.).

  A pair of pulleys 7 and 8 are rotatably arranged on the gantry 9 on the upstream side and the downstream side. One of the pulleys 7 and 8 is rotationally driven by a motor or the like. An endless belt 10 is stretched between the pulleys 7 and 8. The endless belt 10 is made of a wire mesh and has a large number of minute apertures communicating with the front and back surfaces. Sprockets 11 are provided at both ends of the pulleys 7 and 8, respectively, and each sprocket 11 is engaged with a chain 12 provided at both side edges in the width direction of the endless belt 10.

  The endless belt 10 is supported from below by a support plate (not shown) on the conveyance track side 14 that performs gravity filtration, and is supported from below by a receiving roller 16 on the return track side 15. As shown in FIG. 5, the gantry 9 is provided with a pair of partition plates 17 whose lower ends are in sliding contact with both side portions of the endless belt 10 on the conveyance track side 14 from above. As shown in FIG. 2, the two partition plates 17 are located inside the pair of chains 12, and prevent the concentration target sludge 3 from falling from between the two partition plates 17 to both outer sides. The partition plate 17 is made of rubber or resin.

  Further, as shown in FIG. 1, a cleaning device 19 for cleaning the endless belt 10 on the return track side 15 is provided on the upstream side. The cleaning device 19 includes a first cleaning machine 21 that collects the separated water dropped from the endless belt 10 on the conveyance track side 14 by a collecting tray 20 and supplies the separated water to the endless belt 10 on the return track side 15, and the cleaning water to the belt. And a second cleaning machine 23 that injects the endless belt 10 on the return track side 15 from the cleaning nozzle 22.

  The belt type concentrator 1 is provided with a scraper device 30. As shown in FIGS. 3 to 5, the scraper device 30 includes a scraper 31 provided on the transport track 29 of the concentration target sludge 3, a rotary shaft 32 provided above the scraper 31, the scraper 31 and the rotary shaft. A plurality of thin plate-like connecting members 33 connected to the cylinder 32 and a cylinder 34 (driving device) for rotating the rotary shaft 32 are configured.

  The scraper 31 is a flat plate-like member that is inserted between the partition plates 17 in the width direction and is inclined obliquely upward from the upstream side to the downstream side in the transport direction of the concentration target sludge 3. The upstream lower end 31a of the scraper 31 is pointed like a blade, and is in line contact with the upper surface of the endless belt 10 in the width direction.

  The rotating shaft 32 is disposed in the width direction of the endless belt 10, and both end portions thereof are supported on the gantry 9 via bearings 35. The rotating shaft 32 is formed in a tubular shape with one end closed, and a cleaning water supply hose 36 for supplying cleaning water is connected to the other end of the rotating shaft 32. The rotating shaft 32 is provided with a plurality of scraper cleaning nozzles 37 that spray the cleaning water onto the upper surface of the scraper 31.

  The cylinder 34 is connected to an arm 38 provided at one end of the rotating shaft 32. When the piston rod 34a of the cylinder 34 is expanded and contracted, the rotary shaft 32 rotates, and the scraper 31 has a peeling position C (see the solid line in FIG. 4) where the upstream lower end 31a contacts the upper surface of the endless belt 10, and endlessness. The position is switched to the retreat position D (see the phantom line in FIG. 4) for retreating above the belt 10.

  A receiving plate 40 (an example of a receiving member) that receives the endless belt 10 on the transport track side 14 from the lower side (back side) is provided below the lower end 31 a on the upstream side of the scraper 31. The upper surface of the receiving plate 40 is in sliding contact with the lower surface (back surface) of the endless belt 10. The scraper device 30 and the receiving plate 40 are respectively installed at a plurality of locations (for example, 3 locations in FIG. 1) from the upstream side to the downstream side of the transport track 29.

Hereinafter, the operation of the above configuration will be described.
By rotating one of the pulleys 7 and 8, the endless belt 10 rotates via the sprocket 11 and the chain 12. As shown in FIG. 1, the concentration target sludge 3 to which the flocculant has been added in advance and supplied from the supply unit 2 onto the endless belt 10 on the transport track side 14 is moved upstream on the transport track 29 by the endless belt 10. Gravity filtration while being conveyed from the downstream. At this time, as shown in FIG. 6A, since the lower part of the concentration target sludge 3 tends to be dehydrated before the upper part, a consolidated layer A is formed at the lower part of the concentrated sludge 3 and this consolidated layer. A phenomenon in which the upper part of A becomes the free water layer B and the dehydration of the upper part (free water layer B) of the sludge 3 to be concentrated is inhibited by the consolidation layer A occurs.

  In the gravity filtration as described above, the sludge 3 to be concentrated is in the process of being transported from the upstream side to the downstream side, as shown in FIG. 6B, by the scrapers 31 at the peeling position C, upward from the endless belt 10. When separating and overcoming the scraper 31, the free water layer B of the sludge 3 to be concentrated precedes the consolidated layer A downstream due to the frictional resistance between the upper surface of the scraper 31 and the consolidated layer A. Thereby, when the concentration target sludge 3 falls from the downstream upper end of the scraper 31 onto the endless belt 10, the concentration target sludge 3 goes up and down in an attempt to sink the free water layer B below the consolidation layer A, The consolidated layer A is divided or converted from the lower part to the upper part of the sludge 3 to be concentrated. Thereby, in the downstream of the scraper 31, inhibition of dewatering of the concentration target sludge 3 by the compacted layer A is reduced, and the dewatering efficiency is improved.

Moreover, since the upper surface of the endless belt 10 is renewed when the sludge 3 to be concentrated is peeled upward from the endless belt 10 by each scraper 31, the dewatering efficiency is further improved.
Moreover, since each scraper 31 becomes resistance when conveying the concentration target sludge 3 from the upstream side to the downstream side, the residence time of the concentration target sludge 3 becomes longer on the upstream side of the scraper 31, and the upstream lower end of the scraper 31. Since the concentration target sludge 3 located in the vicinity of 31a is compressed and dehydrated, the dewatering efficiency is improved in the vicinity of the lower end 31a on the upstream side of the scraper 31. In particular, as shown in FIG. 2, the concentration target sludge 3 is likely to stay in the portion surrounded by the scraper 31 and the partition plate 17, thereby increasing the residence time of the concentration target sludge 3 in the surrounded portion, Since the concentration target sludge 3 in the enclosed portion is compressed and dehydrated by the concentration target sludge 3 conveyed from the upstream side, the dewatering efficiency in the enclosed portion is improved.

  Furthermore, since the lower end 31 a on the upstream side of each scraper 31 is pointed like a blade and is in line contact with the upper surface of the endless belt 10 instead of surface contact, the concentration target sludge 3 is upstream of the scraper 31. Intrusion between the lower end 31a and the upper surface of the endless belt 10 can be prevented, and the endless belt 10 is less likely to be clogged.

  In addition, by providing the receiving plate 40, the scraper 31 prevents the endless belt 10 from being excessively pushed downward while the upstream lower end 31a of the scraper 31 is surely in line contact with the upper surface of the endless belt 10. be able to.

  In addition, after the dehydration and concentration step for the concentration target sludge 3 as described above is completed, the supply of the concentration target sludge 3 is stopped, and the endless belt 10 is rotated and the endless belt 10 is rotated to endlessly. When cleaning is performed by injecting cleaning water onto the belt 10, the piston rod 34a of the cylinder 34 is shortened to rotate the rotating shaft 32 and the scrapers 31 are retracted from the peeling position C as shown by phantom lines in FIG. Switch to D. Accordingly, since each scraper 31 is retreated above the endless belt 10 at the time of cleaning, the concentration target sludge 3 does not remain at the lower end on the upstream side of the scraper 31, and thus the endless belt 10 is sufficiently cleaned. .

  Further, by supplying the cleaning water from the cleaning water supply hose 36 into the rotary shaft 32, the cleaning water is jetted from the scraper cleaning nozzles 37 to the upper surface of the scraper 31, so that the scraper 31 is sufficiently cleaned. .

  In the first embodiment, as shown in FIG. 1, the scraper devices 30 are provided at three locations, but may be provided at a plurality of locations other than the three locations or only at one location. FIG. 7 is a graph showing the relationship between the filtration time and the concentrated sludge concentration when the number of installed scrapers 31 is 0-3. According to this, when the filtration time is constant, the concentrated sludge concentration increases as the number of scrapers 31 increases, and when the concentrated sludge concentration is constant, the filtration time decreases as the number of scrapers 31 increases. There is a tendency.

  In the first embodiment, as shown in FIG. 4, the scraper 31 is rotated to switch between the peeling position C and the retracted position D. However, the scraper 31 is slid vertically to retract from the peeling position C. You may comprise so that it may switch to the position D. Further, the scraper 31 may be manually switched between the peeling position C and the retracted position D without using the cylinder 34.

  In the first embodiment, as shown in FIG. 4, the scraper 31 is attached to the lower end of the connecting member 33 by welding or the like, and the inclination angle of the scraper 31 with respect to the endless belt 10 is fixed. 31 may be attached to the lower end of the connecting member 33 with bolts and nuts, and the inclination angle of the scraper 31 may be adjusted by loosening the bolts and nuts.

In the first embodiment, the endless belt 10 on the conveying track side 14 may be pressed downward from above by each scraper 31 to apply tension to the endless belt 10.
In the first embodiment, a thin plate is used for each connecting member 33 as shown in FIG. 3, but in the second embodiment described below, each connecting member is shown in FIG. As 33, an angle having a V-shaped cross section is used. Each of the connecting members 33 is arranged such that the apex angle portion faces the upstream side, and the width gradually increases toward the downstream side.

  According to this, in the dehydration and concentration step, when the concentration target sludge 3 is transported from the upstream side to the downstream side over the scraper 31, the concentration target sludge 3 is scraped by the respective connection members 33, and the downstream side of each connection member 33. , An exposed portion 44 (a portion surrounded by an imaginary line in FIG. 8) in which a part of the surface of the endless belt 10 is exposed is formed in a groove shape. Thereby, the adhering water of the sludge 3 to be concentrated flows into the endless belt 10 at the exposed portion 44 and is filtered, so that the drainage of the endless belt 10 is improved.

  In the second embodiment, an angle having a V-shaped cross section is used as the connecting member 33 in order to generate the exposed portion 44. However, the connection section 33 is not limited to this shape. A triangle or a quadrangle may be used.

  In the first embodiment, as shown by the solid line in FIG. 4, each scraper 31 is fixed at the peeling position C during dehydration and concentration. In the third embodiment described below, in FIG. As shown in FIG. 10, a rotating roller 49 including a plurality of scrapers 48 is provided.

  That is, the rotating roller 49 is provided on the transport track 29 and is rotatably held around a rotation axis 50 in the width direction orthogonal to the transport track 29. Both ends of the support shaft 53 of the rotating roller 49 are supported on the gantry 9 via bearings 54.

  Each scraper 48 has a bowl-shaped cross section, is attached to the outer peripheral surface of the rotating roller 49, and the concentrated sludge 3 is removed from the upper surface of the endless belt 10 at a scraping position E below the rotating shaft 50. Then, it is rotated together with the rotating roller 49, and the concentration target sludge 3 is dropped onto the upper surface of the endless belt 10 at the return position F closer to the downstream side than the scraping position E.

The tip of each scraper 48 is pointed like a blade, and is configured to be in line contact with the upper surface of the endless belt 10 in the width direction.
Further, roller-side sprockets 51 are provided at both ends of the support shaft 53 of the rotating roller 49, and an intermediate sprocket 52 that meshes with the roller-side sprocket 51 and the chain 12 of the endless belt 10 is provided on the gantry 9.

In the scraping position E, a receiving plate 40 (an example of a receiving member) that receives the endless belt 10 on the conveyance track side 14 from the lower side (back side) is provided.
According to this, in the dehydration and concentration step, the endless belt 10 rotates, whereby the rotating roller 49 rotates in one direction G via the chain 12 and the sprockets 51 and 52. The to-be-concentrated sludge 3 conveyed by the endless belt 10 is scraped by the scrapers 48 at the scraping position E, and is discharged from the scrapers 48 to the upper surface of the endless belt 10 at the return position F.

  At this time, the consolidation layer A and the free water layer B of the sludge 3 to be concentrated that have been scraped by the scraper 48 at the scraping position E are discharged to the endless belt 10 in an inverted state at the return position F. In the return position F, the free water layer B exists on the upper surface of the endless belt 10, and the consolidated layer A exists on the free water layer B. Thereby, the inhibition of dewatering of the concentration target sludge 3 by the consolidated layer A is reduced, and the dewatering efficiency is improved.

In the said 3rd Embodiment, although the cross section of the scraper 48 is formed in hook shape, it is not limited to hook shape.
In each of the above-described embodiments, the receiving plate 40 is used as an example of the receiving member. However, the endless belt 10 may be received from the lower side (back side) using a freely rotatable receiving roller.

  In each of the embodiments described above, a resin such as polyethylene is used as the material of the scrapers 31 and 48, but a metal such as iron may be used.

It is a schematic side view of the belt type concentrator in the 1st Embodiment of this invention. FIG. 3 is a partially cutaway plan view of the belt type concentrator. It is a top view of the scraper device of the belt type concentrator. It is a XX arrow line view in FIG. It is a YY arrow line view in FIG. It is a side view explaining the function of the scraper of the belt type concentrator, wherein (a) shows a state where the sludge is upstream of the scraper, and (b) shows a state where the sludge is transported over the scraper. Indicates. It is a graph which shows the relationship between the filtration time and concentrated sludge density | concentration when the number of installations of the scraper of a belt-type concentrator is 0-3. It is a top view of the scraper apparatus of the belt type concentrator in the 2nd Embodiment of this invention. It is a side view of the scraper apparatus of the belt type concentrator in the 3rd Embodiment of this invention. It is a XX arrow line view in FIG. It is a side view which shows the dewatering concentration of the sludge using the conventional belt-type concentrator. It is sectional drawing of the resistor provided in the conventional belt type concentrator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Belt type concentrator 3 Concentration object sludge 10 Endless belt 17 Partition plate 31 Scraper 40 Receiving plate (receiving member)
C Peeling position D Retraction position

Claims (4)

A belt-type concentrator having a mesh-like rotatable endless belt for gravity-filtering the sludge to be concentrated, wherein a scraper is provided on a transport track of the sludge to be concentrated, and the scraper is located upstream in the sludge transport direction. A belt-type concentrator characterized in that it is inclined obliquely upward toward the downstream side, and the upstream lower end of the scraper is formed in a blade shape and is in line contact with the upper surface of the endless belt in the width direction. Machine. 2. The belt type concentrator according to claim 1, wherein a receiving member for receiving the endless belt from the lower side is provided below the lower end on the upstream side of the scraper. 3. The scraper is configured to be switchable between a retracted position where the scraper is retracted above the endless belt and a peeling position where the upstream lower end is in contact with the upper surface of the endless belt. Belt type concentrator. A pair of partition plates are provided for preventing sludge to be concentrated from spilling from the endless belt to both outer sides, and the scraper is inserted between the pair of partition plates. Item 4. The belt type concentrator according to any one of Items 3 to 4.

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