JP4081759B2 - Screw press - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screw press that performs filtration and dewatering while rotating an outer cylinder of a concentration zone, and more specifically, an improvement of a screw press that can perform concentration and dewatering while preventing clogging of a screen even with low-concentration sludge, thereby improving dewatering efficiency. It is about.
[0002]
[Prior art]
Conventionally, when organic sludge such as sewage and human waste is dehydrated with a screw press, a polymer flocculant is added to the sludge and agitated to generate floc, and this coagulated sludge is supplied to the screw press for dehydration. It is carried out. However, with sludge having a low solids concentration, it has been difficult to efficiently drain a large amount of separated liquid at the front stage of the outer cylinder screen at high speed. In particular, in the former stage, a thin film of a polymer flocculant is generated on the inner surface of the screen, and the drainage is hindered, so that residues are attached and clogging is likely to occur. For this reason, after concentrating low concentration sludge with concentrators, such as a centrifugal concentrator and a flotation | concentration concentrator, the method of filtering and dewatering a concentrated sludge with a screw press is taken. However, the use of a concentrator and a screw press has a problem in that the installation area is large and the driving power cost is high. In addition, there is a problem that maintenance is also required.
[0003]
In order to solve the above problems, the outer half screen of the outer cylinder screen is configured as a concentrating zone, and the latter half is configured as a filtration / dehydration zone. Thus, screw presses having a concentration function are known. However, even in a screw press having the above-mentioned concentration function, in sludge with a low solid matter concentration, a thin film made of a polymer flocculant is generated on the inner surface of the screen in the concentration part in front of the outer cylinder screen, and the drainage performance is inhibited As a result, residue adheres and clogging occurs, and it is difficult to efficiently drain a large amount of separation liquid at high speed.
[0004]
[Patent Document 1]
Japanese Patent Publication No. 3-78123 [Patent Document 2]
JP-A 64-2920
[Problems to be solved by the invention]
In order to solve the above-mentioned problems of the prior art, Patent Document 1 discloses a method for preventing clogging of the outer cylinder screen by continuously injecting cleaning water while rotating the outer cylinder screen. However, in the method in Patent Document 1, the sprayed washing water penetrates through the small hole of the screen and enters the outer cylinder, the concentrated sludge is diluted, and the concentration effect may be reduced by half. May affect the dewatering efficiency and water content of the cake.
[0006]
In Patent Document 2, as a method of preventing clogging of the outer cylinder screen, a high-pressure squeezing is performed by configuring the screen with a wedge wire having a substantially triangular cross section and a narrow inner peripheral surface side and a wide outer peripheral surface side slit. There is a description that impurities entering the slit can be prevented from being clogged because they gradually escape to the outside. Further, in Patent Document 2, there is a description in which the rear end portion of the screw shaft is formed in a cylindrical shape with a screen stretched on the outer peripheral surface, so that a dehydrating efficiency is improved as a filtering portion.
[0007]
However, in Patent Document 2, when low-concentration sludge aggregated by the polymer flocculant is supplied to the front stage, it is difficult to drain a large amount of filtrate from a narrow slit at a high speed. A thin film made of a polymer flocculant is formed on the inner surface of the tube screen and the outer surface of the screw shaft, which may deteriorate the drainage and reduce the dewatering efficiency. And, in order to discharge the filtrate flowing into the inside from the screen surface of the screw shaft, it is sucked by a vacuum pump, and there is a problem that a highly accurate seal structure is required and running costs such as power costs increase. .
[0008]
[Means for Solving the Problems]
The present invention solves the above-mentioned problems in the prior art, and the gist of the invention is to divide an outer cylinder with a screen stretched into a rotatable concentration zone in the first half and a filtration / dehydration zone in the second half. Then, a screw shaft around which screw blades are wound is provided in the divided outer cylinder, and the slurry supplied to the starting end of the outer cylinder in the concentration zone is filtered and dehydrated while rotating the screw shaft. In a screw press that separates the filtrate from the screen of the outer cylinder and takes out the cake from the end of the outer cylinder of the filtration / dehydration zone, the screw shaft is divided in the front-rear direction at the rear end, and the screw at the rear end A screen is stretched on the shaft, and a scraper is disposed on the outer peripheral portion of the screw blade from the start end to the rear end, and the screw shaft scraper is also provided on the inner peripheral portion of the screw blade. A scraper is arranged opposite to the lean surface, and this scraper is elastically slidably contacted with the inner peripheral surface of the outer cylinder and the screen surface of the screw shaft, and filtration and dehydration are performed while rotating the screw shaft. A screw press in which a clutch is disposed in a division part of the outer cylinder so that the concentration zone and the filtration / dehydration zone can be freely connected and disconnected.
[0009]
Then, the rear end portion of the divided screw shaft screen is fixed and the other end portion is rotatable, or a wedge wire is used as a screen stretched on the screw shaft, and the slit side of the wedge wire is filtered. The surface. Further, the drive shaft for driving the screw shaft is hollow, and a plurality of cleaning nozzles are disposed on the outer peripheral portion of the drive shaft at a position facing the inner peripheral surface of the screen of the screw shaft so as to clean the screen. It is a screw press.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The screw press according to the present invention is configured as described above, and a polymer flocculant is added to and stirred in organic sludge such as sewage and human waste, and the sludge that has generated flocs flocs is pumped to the screw press supply port. Then, the sludge flows into the supply path of the screw shaft on the outer cylinder start end side and is supplied between the screw blades in the concentration zone through the supply hole opened in the screw shaft, so that the aggregate floc is affected by the screw blades. It flows into the start end of the outer cylinder without being destroyed.
[0011]
The sludge supplied to the concentration zone is concentrated by being discharged from the screen of the outer cylinder while being transferred by the rotating screw blades. By rotating the outer cylinder of the concentrating zone in the direction opposite to the screw shaft, the number of rotations of the screw blade is relatively increased, and the number of sliding contacts between the scraper and the screen disposed at the tip of the screw blade is reduced. A large amount of the filtrate can be discharged by scraping the cake layer and the thin film of the polymer flocculant, which are increased and deposited on the screen, to regenerate the filtration surface to be clogged. And since sludge is transferred with screw blades while preventing clogging of the screen with a scraper, it is possible to efficiently concentrate even sludge with a low solids concentration and a large water load.
[0012]
Next, the sludge concentrated in the concentration zone is transferred to the filtration / dehydration zone and filtered / dehydrated by the screw blades in the latter half. At this time, the outer cylinder of the concentration zone and the outer cylinder of the filtration / dehydration zone are formed into a continuous cylindrical shape, and the diameter of the screw shaft is increased in a tapered shape from the start end to the rear end in the outer cylinder. Since the gap between the outer cylinder and the screw shaft is relatively reduced toward the rear end side, the volume between the screw blades is gradually reduced, and the pressure applied to the sludge is increased. The dehydrated cake can be taken out from the discharge port at the end. Furthermore, the rear end of the screw shaft is formed in a cylindrical shape, and a screen is stretched around the outer peripheral surface to form a filtration surface. A scraper is disposed on the screw blade that contacts the screen surface. While preventing clogging, both sides can be filtered with a screen of an outer cylinder and a screw shaft, and a dehydrated cake with a low water content can be obtained, and the amount of sludge treated is also increased. Embodiments of a screw press according to the present invention will be described in detail below with reference to the drawings.
[0013]
【Example】
FIG. 1 is a longitudinal side view of a screw press according to the present invention, in which a screw press 1 is supported by front and rear frames 2 and 3, and a circumference of an outer cylinder 4 divided into a concentration zone A and a filtration / dehydration zone B. A screen 5 is stretched on the part, and the diameter of the outer cylinder 4 is increased in a tapered manner from the start end to the rear end, and a screw shaft 7 having screw blades 6 wound around the outer peripheral surface is attached to the frame 2. , 3. The screw shaft 7 is freely rotatable by a driving machine 8. The outer cylinder 4 divided into the concentration zone A and the filtration / dehydration zone B can be connected and disengaged by a clutch 9 disposed in the division part. During normal concentration, filtration / dehydration operation, the outer cylinder 4 is in a dissociated state, and only the outer cylinder 4a of the concentration zone A is rotated by the drive unit 10 and is outside the filtration / dehydration zone B. The cylinder 4b is in a fixed state. The rotating direction of the outer cylinder 4a is rotated in the direction opposite to the rotating direction of the screw shaft 7 described later.
[0014]
The sludge aggregated by the polymer flocculant is supplied from the supply port 11 opened at the tip of the screw shaft 7, and from the supply hole 12 opened at the outer peripheral surface of the screw shaft 7, the concentration zone A of the outer cylinder 4 Let it flow into the beginning. The infiltrated coagulated sludge is separated and discharged from the screen 5 of the outer cylinder 4 while being transferred by the screw blade 6 and concentrated. By rotating the outer cylinder 4a of the concentration zone A in the first half in the reverse direction to the screw shaft 7, the number of sliding contacts between the scraper 13a (described later) disposed at the tip of the screw blade 6 and the screen 5 increases. Then, the cake layer deposited on the inner peripheral surface of the screen 5 or a thin film made of the polymer flocculant is scraped to regenerate the screen 5 surface, so that clogging can be prevented and the filtrate can be discharged continuously. Since the screen 5 is composed of a punching plate having a large aperture ratio (approximately 20 to 40%), a large amount of filtrate can be discharged, and even sludge with a low solids concentration and a large water load can be efficiently used. It can be concentrated. The sludge concentrated in the concentration zone A is transferred to the filtration / dehydration zone B by the screw blade 6, and further moves to the rear end while discharging the filtrate from the screen 5 and depressurizing / dehydrating. The screw shaft 7 is divided at the rear end portion, the screw shaft 14 at the rear end portion is formed in a cylindrical shape, and a screen 15 is stretched around the outer peripheral surface to form a filtration surface.
[0015]
Based on FIG. 2, the screw shaft 14 at the rear end will be described. On the outer peripheral surface of the screw shaft 14 formed in a cylindrical shape, a screen 15 made of a wedge wire composed of a large number of members each having a substantially triangular cross section is stretched. Since C is formed and dehydration is performed from the inner and outer surfaces in the double-sided filtration zone C, a dehydrated cake having a lower water content can be taken out from the discharge port 16. A presser 17 is provided opposite to the discharge port 16 so that the opening amount of the discharge port 16 is adjusted while applying back pressure to the dehydrated cake. As shown in FIG. 5, the wedge wire is stretched so that the slit side becomes an outer peripheral surface, and the slit is parallel to or orthogonal to the axis of the screw shaft 14 as shown in FIGS. 3 and 4. Either is acceptable. A blind plate 18 is stretched at the end of the screw shaft 14 in contact with the tip of the presser 17.
[0016]
Next, the screw shafts 7 and 14 will be described in detail with reference to FIGS. A side plate 19 is fixed to an end portion of the screw shaft 7, and a drive shaft 20 is screwed to the side plate 19. By rotating the drive shaft 20, the screw shaft 7 is also rotated. At this time, the screw shaft 14 does not rotate and is in a fixed state, and is in sliding contact with the side plate 19 and the drive shaft 20 by the sliding members 21 and 22. The drive shaft 20 has a hollow shape, and a plurality of cleaning nozzles 23 for cleaning the screen 15 are arranged at equal pitches on the outer peripheral portion of the drive shaft 20 so as to face the inner peripheral surface of the screen 15. is doing. The screw blades 6 having the same pitch are continuously wound around the outer peripheral surfaces of the screw shafts 7 and 14 from the start end portion of the screw shaft 7 to the rear end portion of the screw shaft 14. It is welded to the screw shaft 7. The screw blade 6 of the screw shaft 14 part has a slight gap with the screen 15 surface, and only the screw blade 6 rotates integrally with the screw shaft 7. The screw blade 6 is also provided with a slight gap on the inner surface of the screen 5 stretched on the outer cylinder 4 so as to prevent wear due to contact between the screw blade 6 and the screens 5 and 15.
[0017]
The screw blades 6 are provided with scrapers 13a and 13b shown in FIG. 5 in order to prevent the screens 5 and 15 from being clogged. The scraper 13 a is continuously disposed on the outer peripheral surface portion of the screw blade 6 from the start end to the end so as to press against the inner surface of the screen 5. The scraper 13a is formed in a series of strips, and is sandwiched between the outer periphery of the screw blade 6 by a presser plate 24 and fixed by bolts 25 and nuts 26 at an equal pitch. Similarly to the scraper 13a, the presser plate 24 is configured in a series of strips continuous from the start end to the end of the screw blade 6. And the scraper 13b is continuously arrange | positioned by the internal peripheral surface part of the screw blade | wing 6 so that the outer surface of the screen 15 of the screw shaft 14 may be pressed. Similar to the scraper 13a, the scraper 13b is sandwiched between the inner peripheral portions of the screw blades 6 by a pressing plate 27 and fixed with bolts 25 and nuts 26 at an equal pitch. The holding plate 27 is also formed in a continuous series of strips. The scrapers 13a and 13b are made of an elastic material such as rubber or resin, and the penetrating portion of the bolt 25 is a long hole, so that the pressing force is weakened due to wear due to sliding contact with the screens 5 and 15. In this case, the pressing force can be easily adjusted.
[0018]
After the filtration / dehydration operation is completed or when the screens 5 and 15 are clogged, the outer cylinder 4 divided into the concentration zone A and the filtration / dehydration zone B is integrally connected by the clutch 9, and the outer cylinder 4 The cleaning water is sprayed from the cleaning tube 28 toward the outer surface of the screen 5 of the outer cylinder 4 and the cleaning water is also supplied from the cleaning water supply port 29 connected to the starting end of the hollow drive shaft 20. The screens 5 and 15 can be regenerated by spraying cleaning water from the cleaning nozzle 23 toward the inner surface of the screen 15 while rotating the drive shaft 20. The washing waste water and filtrate that have fallen into the screw shaft 14 are drained from the drain pipe 30 to the drain trough 31. Incidentally, the washing drainage of the screen 5 and the filtrate during the filtration operation are also collected in the drainage trough 31 and discharged from the drainage port 32 to the outside of the apparatus.
[0019]
【The invention's effect】
The screw press of the present invention is configured as described above, and by rotating the outer cylinder of the concentration zone in the direction opposite to the screw shaft, the rotation speed of the screw blades in the concentration zone is relatively increased, and the outer periphery of the screw blades The scraper placed in the section scrapes off the cake layer that accumulates on the screen surface of the outer cylinder and causes clogging and thins the polymer flocculant to regenerate the filtration surface. Efficient concentration and dewatering can be achieved even with sludge with a large water load. Then, the screw shaft is divided at the rear end portion, a screen is stretched on the outer peripheral surface of the screw shaft at the rear end portion, and a scraper is disposed on the inner peripheral portion of the screw blade facing the screen. Since the surface is regenerated, both sides of the dehydrated cake are filtered from the inner and outer surfaces of the dehydrated cake at the rear end where the pressure applied to the dehydrated cake is high, and the filtrate can be discharged efficiently, and the dehydrated cake has a low water content. The amount of sludge can be increased.
[Brief description of the drawings]
FIG. 1 is a partially longitudinal side view of a screw press according to the present invention.
FIG. 2 is a longitudinal side view of a main part of a screw press according to the present invention.
FIG. 3 is a schematic oblique view of a screw shaft with a screen stretched in the same manner.
FIG. 4 is a schematic perspective view of another embodiment of a screw shaft with a screen stretched thereon.
FIG. 5 is a partially longitudinal side view of a scraper attached to a screw blade.
[Explanation of symbols]
1 Screw press 4, 4a, 4b Outer cylinder 5, 15 Screen 6 Screw blade 7, 14 Screw shaft 9 Clutch 13a, 13b Scraper 20 Drive shaft 23 Cleaning nozzle A Concentration zone B Filtration / dehydration zone

Claims (5)

The outer cylinder (4) with the screen (5) stretched is divided into a rotatable concentration zone (A) in the first half and a filtration / dehydration zone (B) in the second half, and the inside of the divided outer cylinder (4) A taper-shaped screw shaft (7) around which a screw blade (6) is wound is installed, and slurry supplied to the start end of the outer cylinder (4a) of the concentration zone (A) is rotated by the screw shaft (7). In the screw press (1) that performs filtration and dehydration, separates the filtrate from the screen (5), and takes out the cake from the end of the outer cylinder (4b) of the filtration and dehydration zone (B), The shaft (7) is divided at the rear end portion, the screw shaft (14) at the rear end portion is formed in a cylindrical shape, a screen (15) is stretched on the outer peripheral surface, and the outer peripheral portion of the screw blade (6) Scraper (13a) from start to end In addition, a scraper (13b) is disposed on the inner peripheral portion of the screw blade (6) so as to face the screen (15) surface of the screw shaft (14), and the scraper (13a, 13b) is removed. A screw press characterized by elastically slidingly contacting the inner peripheral surface of the cylinder (4) and the screen (15) surface of the screw shaft (14), and performing filtration and dehydration while rotating the screw shaft (7). . The screw press according to claim 1, wherein the screw shaft (7) is rotatable and the screw shaft (14) at the rear end portion is fixed. The screw press according to claim 1 or 2, wherein a wedge wire is used as the screen (15) stretched around the screw shaft (14), and the slit side of the wedge wire is used as a filtration surface. The drive shaft (20) for driving the screw shaft (7) is hollow, and a plurality of positions are provided on the outer peripheral portion of the drive shaft (20) so as to face the inner peripheral surface of the screen (15) of the screw shaft (14). The screw press according to any one of claims 1 to 3, wherein a cleaning nozzle (23) is provided to clean the screen (15). The clutch (9) is arranged in the division part of the outer cylinder (4), and the concentration zone (A) and the filtration / dehydration zone (B) are connected and disengaged freely. The screw press according to any one of 4.

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