JP3615955B2 - Centrifugal dehydrator - Google Patents

Description

[0001]
[Industrial application fields]
In the present invention, concentration, dehydration, solids and separated water of sewage sludge and industrial wastewater are collected by centrifugal force. The present invention relates to a straight barrel type centrifugal dewatering apparatus.
[0002]
[Prior art]
For solid-liquid separation of sludge and the like, a decanter type centrifugal dehydrator is generally used. As shown in FIG. 18, this dehydrator has an inner cylinder (inner rotating cylinder) in a bowl (outer rotating cylinder) 1 that is formed by connecting a conical cylinder 31 to the tip of a horizontally long straight body portion 30. 11) A screw conveyor 10 provided with a spiral blade 12 on 11 and rotated with a relative speed difference from the bowl 1 is accommodated, and a raw solution a such as sludge is supplied from the inner cylinder 11 into the front and rear central parts of the bowl 1 to obtain centrifugal force. In this way, solid-liquid separation is performed. Then, the dewatered cake b settled and separated by the centrifugal force in the bowl 1 is sequentially scraped toward the front end by the spiral blade 12, and further subjected to the compacting and drainage action in the conical cylinder 31, The separation liquid C is discharged from the mud discharge port 6 and overflows from the discharge hole 7 provided in the rear end wall 3 of the bowl 1 on the opposite side.
[0003]
In this decanter type centrifuge, since the filtrate is stored in the bowl 1, it is the same as the separation liquid discharge hole 32 in order to prevent the filtrate from coming out of the mud discharge port 6 for discharging the cake. It is characterized in that it requires a conical cylinder 31 whose front end is narrowed to a level (water level) above a certain level.
[0004]
[Problems to be solved by the invention]
However, in the conventional decanter type centrifugal dehydrator, when the stock solution a is supplied to the center of the bowl 1, the bowl straight body 30 immediately after the supply is solidified by a high centrifugal force field (about 2000 to 3000G). Although the liquid is separated, the bowl conical portion 31 from which the dewatered cake b is discharged has a relatively high water content near the rotation center of the straight body portion 30 because the distance (diameter) from the rotation center is short. Only the cake is discharged, and the cake having a relatively low water content far from the center of rotation is not discharged while remaining.
[0005]
Further, since the dewatered cake b passes through a large inclined conical cylinder for discharging it beyond the water level in the bowl, slipping occurs at this portion, resulting in poor discharge, and sludge is discharged together with the separated liquid. There are drawbacks such as discharge from the outlet 7 and the separated liquid becoming dirty. In addition, since the dehydrated cake to be discharged has a relatively high moisture content close to the rotation center of the straight body portion 31, the bowl 1 is rotated in order to reduce the moisture content of the dehydrated cake to be discharged. The actual situation is that the number is increased more than necessary (about 2,000 to 3,000 rpm). Therefore, it requires a lot of power.
[0006]
The present invention has been made to solve the problems in the decanter type centrifugal dehydrator as described above. The dehydration efficiency can be improved by promoting the dehydration, and the bowl rotational speed can be reduced. It is an object of the present invention to provide a straight barrel type centrifugal dewatering device that can save and make the device simple and compact.
[0007]
[Means for Solving the Problems]
In the dehydrating apparatus of the present invention, in order to perform efficient solid-liquid separation and quick discharge of the separated liquid, a filtrate discharge section for discharging the separated liquid is provided at a position where the distance from the rotation center becomes long. . As a result, the feed stock solution is promptly separated and drained to prevent the formation of a water surface in the bowl, and the residence time of the dehydrated cake can be increased. The bowl is formed in a straight barrel shape, and a discharge ring is formed narrowly by projecting a suppression ring and a suppression rod in order to consolidate the dehydrated cake at the front end where the dehydrated cake is discharged. The content of dehydrated cake is reduced. In the apparatus of the present invention, the separation liquid discharge port is provided on the outer peripheral portion of the rear end wall of the bowl, so that the separation liquid is quickly discharged and the water surface in the bowl hardly occurs.
[0008]
As soon as the stock solution is supplied into the bowl, the separated solution is discharged by centrifugation, and the solid dehydrated cake is further conveyed, scraped and discharged while being centrifuged. As a result, the moisture content of the dehydrated cake can be reduced and the number of rotations of the bowl can be reduced, so that less power is required. Further, since the separation liquid is discharged immediately after the stock solution is supplied, the water level in the bowl becomes extremely shallow. Therefore, it is not necessary to provide the long inclined cone part required for discharging the dewatered cake beyond the surface of the water, which is a disadvantage of the conventional decanter type centrifugal dehydrator. Simplification can also be achieved.
[0009]
Further, in the apparatus of the present invention, the suppression ring provided at the front end of the ball can be adjusted to advance and retreat in the length direction of the bowl so that the width of the discharge port of the dewatered cake can be adjusted. In addition, a filtrate discharge point can be provided on the peripheral wall of the rear part of the bowl, and further, a scraping blade for scraping off sludge adhering to the filtrate discharge part provided on the peripheral wall of the bowl is provided. can do.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4 show an embodiment of the apparatus of the present invention, FIGS. 5 to 13 show other embodiments of the dewatered cake discharge section, and FIGS. 14 to 17 show other embodiments of the separation liquid discharge section. An example is shown.
[0011]
1 to 4, reference numeral 1 denotes a bowl (outer rotating cylinder) that is rotated at a high speed. The bowl has a horizontal cylindrical shape, and hollow shafts 4 and 5 protrude from the central portions of the front and rear end walls 2 and 3, respectively. It is provided, is supported by a bearing (not shown), and is rotated at a high speed by a driving device. And in the peripheral wall of the front-end part of the bowl 1, the several drainage port 6 is spaced apart along the circumferential direction.
[0012]
The rear end wall 3 of the bowl 1 is provided with a separation liquid discharge port 7 located in the vicinity of the outer peripheral portion where the distance from the center of rotation is as long as possible. For example, as shown in FIG. 2, the discharge holes 7 are formed by separating a plurality of fan-shaped ones in the circumferential direction, or although not shown in the drawing, many small holes are formed along the outer peripheral portion of the rear end wall 3. It is good to provide a separate. In the present invention, it is important that the separation liquid can be discharged at a position as far as possible from the center of rotation, so that the separation liquid can be discharged quickly and the water level in the bowl 1 can be reduced. Little or no formation will result in a very shallow depth, which improves dewatering performance.
[0013]
In addition, a suppression ring 8 is provided on the inner periphery of the bowl 1 immediately after the drainage port 6 is provided to give a compacting action to the dewatered cake b when discharged. The suppression ring 8 has a mountain-shaped cross section, and its rear end surface is formed into a tapered surface 8a.
[0014]
Reference numeral 10 denotes a screw conveyor accommodated in the bowl 1, and spiral blades 12 are wound around the outer periphery of a horizontal cylindrical rotary drum 11, and both ends thereof protrude into the bowls of the hollow shafts 4 and 5 of the bowl 1. The rotating shaft 13 supported by the portion and inserted through the hollow shaft 4 is rotated with a required speed difference from the bowl 1. A supply chamber 14 for the stock solution a is provided in the rear part of the rotary drum 11, and a supply port 15 communicating with the annular space 17 between the bowl 1 and the rotary drum 11 is opened on the peripheral wall. An undiluted solution supply pipe 16 inserted through the rear hollow shaft 5 of the bowl 1 is provided in the supply chamber 14 so as to open. Further, on the outer periphery of the front end portion of the rotating drum 11 facing the suppression ring 8, a suppression rod 18 having a mountain-shaped cross section larger than the suppression ring 8 is provided with a tapered surface 18 a on the side facing the rear end. A narrow extrusion port 19 is formed between them. The tapered surfaces 8a and 18a may be vertical surfaces instead.
[0015]
In the above apparatus, the stock solution a to be dehydrated enters the supply chamber 14 from the supply pipe 16 as shown by the arrow, is supplied from the supply port 15 into the annular space 17, and is rotated by the centrifugal force of the rotation of the bowl 1 and the screw conveyor 10. The solid blade is conveyed toward the front end by the spiral blade 12 while being separated into solid and liquid. The separated liquid C, which is the separated liquid, is discharged out of the machine through the discharge hole 7 in the rear end wall.
[0016]
The dehydrated cake b containing the solid content and the liquid content is further scraped toward the front end of the bowl 1 by the spiral blade 12 and further subjected to the separation action by centrifugal force, so that the separation of the residual liquid proceeds and the separation The liquid C is also discharged from the discharge hole 7. The dewatered cake b transported to the front part of the bowl 1 is subjected to a compacting action by a suppression ring 8 projecting from the front end part of the bowl 1 and a suppression bar 18 at the front end part of the rotating drum 11, and a narrow discharge port between the two 19 is discharged to the mud outlet 6.
[0017]
In the apparatus of the present invention, the stock solution a is supplied to the rear part of the bowl 1 and is discharged while being conveyed to the front end of the bowl 1, and the separation liquid C is a discharge hole provided in the outer peripheral part of the rear end wall 3 of the bowl 1. 7, the water level in the bowl 1 is much shallower than that of the decanter type. Since the water level is extremely shallow, turbulent flow does not occur in the bowl 1, the residence time of the dewatered cake is increased, and since the bowl 1 is cylindrical, it receives a high centrifugal force over its entire length and is separated. High performance can be maintained. Further, the dewatered cake scraped to the front end of the bowl 1 is compacted there, further drained and discharged. Therefore, the long conical cylinder part at the tip of the straight body part as in the prior art is no longer necessary, the overall length of the bowl can be shortened, and the number of rotations of the bowl can be reduced.
[0018]
5 to 8 show another embodiment of a portion provided with a suppression ring at the tip of the bowl 1. In this embodiment, it is not fixed as in the previous embodiment, but can be adjusted forward and backward with respect to the bowl 1 in its length direction. That is, the suppression ring 20 is a separate body from the bowl 1 and, like the suppression ring 8 described above, has a cross-section that has a chevron shape, and its rear end surface is a tapered surface 21a or a vertical surface. A mounting piece 22 that protrudes into each drainage port 6 spaced in the circumferential direction is provided on the outer peripheral surface of the ring portion 21 that is slidably joined to the inner periphery of 1.
[0019]
Then, between each mounting piece 22 of the suppression ring 20 and the bowl 1 (the rear end surface of the mud discharge port 6), for example, a spacer 23 formed by stacking thin plates is interposed, and a mounting bolt 24 passing through the spacer 23 from the mounting piece 22 is inserted. Is detachably attached to the bowl 1. Therefore, by changing the thickness of the spacer 23, the suppression ring 20 is adjusted to advance and retract in the longitudinal direction of the bowl 1 as shown by the arrow in FIG. As a result, the width of the discharge port 19 formed between this and the opposing suppression rod 18 is adjusted. As a result, the compaction action can be freely adjusted by suppressing the dehydrated cake, the dehydration rate can be improved, a stable dehydrated cake can be obtained, and the present invention can be widely applied to sludge having various properties.
[0020]
In the above embodiment, the top portion 21b of the suppression ring 20 is located behind (the discharge port side) from the top portion 18b of the pressing rod 18. However, as shown in FIG. it can. Further, as shown in FIGS. 10 and 11, the cross-sectional shape of the ring portion 21 of the suppression ring 20 can be a plate having a long diameter in the radial direction, and its rear surface can be formed into a substantially upright surface 21c. The position of the top portion 18b of the suppression rod 18 with respect to the top portion 21b of the ring 20 may be shifted backward (FIG. 10) or forward (FIG. 11).
[0021]
Also, as shown in FIGS. 12 and 13, contrary to the above, the cross-sectional shape of the suppression rod 18 can be a plate-like shape that is long in the radial direction, and its rear surface can be formed into a substantially upright surface 18c. Also in this case, the position of the top portion 18b of the suppression rod 18 with respect to the top portion 21b of the suppression ring 20 can be shifted backward (FIG. 12) or forward (FIG. 13).
[0022]
Further, in the apparatus of the present invention, the filtrate discharge point can be provided on the peripheral wall of the bowl 1. 14 and 15 show such an embodiment. In this embodiment, the rear end wall 3 is not provided with a discharge port, and instead, a filtrate discharge portion 25 is provided on the peripheral wall of the rear portion of the bowl 1, and this filtrate discharge portion 25 is, for example, shown in FIG. As shown in FIG. 10, a large number of discharge holes 26 are formed along the circumferential direction, and a screen 27 made of a porous plastic molded body, a wire mesh, a ceramic, a metal sintered body, a filter cloth, or the like for filtering solid content is provided inside the discharge holes 26. It has a structure attached. The filtrate discharge portion 25 is not limited to the above-described structure, and the structure can be appropriately changed as long as it is a combination of the discharge hole 26 and the screen 27.
[0023]
In this way, in the case where the filtrate discharge portion is provided on the peripheral wall of the bowl 1, the separation liquid C is discharged immediately after the supply of the stock solution, so that almost no water surface is generated in the bowl 1, Therefore, solid-liquid separation and dehydration are performed more efficiently.
[0024]
Further, in the apparatus of the present invention, as shown in FIG. 16, the filtrate discharge points are arranged in the bowl rear end wall 3 as in the embodiment of FIGS. 1 to 5 and in the embodiment of FIGS. It can be provided on the peripheral wall of the bowl 1. That is, the discharge port 7 is provided on the rear end wall, and the filtrate discharge portion 25 is provided on the peripheral wall of the bowl. In this way, since the separation liquid C is discharged from both the discharge port 7 and the filtrate discharge part 25, it is possible to process sludge having a low concentration and efficient processing even for high loads.
[0025]
FIG. 17 shows an embodiment in which means for scraping off the sludge adhering to the filtrate discharge part 25 is provided. That is, in this embodiment, a part of the spiral blade 12 is cut away from the screw conveyor 10 in correspondence with the filtrate discharge part 25, and the tip of the spiral cylinder 11 is in sliding contact with the screen 27. A plurality of sludge scraping blades 28 adhering to the screen 27 are mounted radially. The scraping blade 28 not only simply scrapes the sludge adhering to the screen 27 but also maintains an angle with respect to the axis so as to have a conveying force for the sludge and dehydrated cake. Is preferred. In the embodiment of FIG. 17, the discharge port 7 is provided in the rear end wall 3 of the bowl 1, but the discharge port 7 may not be provided.
[0026]
The sludge that has adhered to the screen 27 of the filtrate discharge unit 25 can be scraped off by the spiral blades 12 of the screw conveyor 10 to some extent. However, there is a slight gap between the spiral blade 12 and the inner surface of the screen 27, and the difference in rotational speed between the bowl 1 and the screw conveyor 10 is slight. Since it is slow, the scraping of the sludge becomes insufficient, the screen 27 becomes clogged, and the discharge of the separated water worsens. Therefore, in the apparatus of this embodiment, a scraping blade 28 slidably contacting the screen 8 is provided so that sludge can be scraped positively.
[0027]
【The invention's effect】
As described above, according to the centrifugal dewatering device of the present invention, the filtrate (separation liquid) discharge part is provided on the peripheral wall far from the axis of the rear part of the bowl or the outer peripheral part of the rear end wall, and the stock solution is filtered. As it is supplied into the rear part of the bowl with the discharge part (discharge hole), a suppression ring and a suppression rod are provided facing the front end of the bowl and the front end of the rotating cylinder of the screw conveyor. There are many excellent effects.
[0028]
(1) Since the stock solution is centrifuged immediately after being supplied and the filtrate is discharged, the surface of the water is hardly formed in the bowl. Therefore, the surface of the water is formed in the bowl as in the conventional machine. It is not necessary to provide a long conical cylinder with a large diameter, and the filtrate is immediately discharged from the vicinity of the peripheral wall of the bowl. Good cake can be transported smoothly.
[0029]
(2) Since the supply of the stock solution and the discharge part of the filtrate are close, when the stock solution is supplied, the centrifugal separation and the discharge of the separated solution are performed immediately, and the dehydration efficiency is high. Even so, dehydration efficiency similar to that of the conventional machine can be obtained and less power is required.
[0030]
(3) The dewatering cake is subjected to compaction at the exit by the repression ring and repression, and the dewatering rate is further improved. In particular, the device that can adjust the retraction ring forward and backward can handle the characteristics of various sludges and is stable. Dehydrated cake can be obtained.
[0031]
(4) Further, in the apparatus in which the filtrate discharge part is provided on the peripheral wall, since the filtration is performed by the screen, the property of the separated water is good and the generation of the water surface in the bowl can be prevented. In the apparatus provided with the sludge scraping blade, the screen can be prevented from being clogged, and the operation efficiency is improved.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing an embodiment of the device of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA of FIG.
FIG. 3 is a sectional view taken along the line BB in FIG.
FIG. 4 is an enlarged side sectional view of the front portion of the device of the present invention.
FIG. 5 is a side sectional view showing another embodiment of the device of the present invention.
FIG. 6 is an enlarged side sectional view of the front portion.
FIG. 7 is a sectional side view of the same.
FIG. 8 is a sectional view taken along the line CC of FIG.
FIG. 9 is a semi-longitudinal longitudinal sectional view of a main part showing another embodiment of a portion provided with a suppression ring and a suppression collar.
FIG. 10 shows still another embodiment.
FIG. 11 shows still another embodiment.
FIG. 12 shows still another embodiment.
FIG. 13 shows still another embodiment.
FIG. 14 is a side sectional view showing another embodiment of the filtrate discharge part.
FIG. 15 is an enlarged side sectional view of a filtrate discharge part.
FIG. 16 is a side sectional view showing still another embodiment of the filtrate discharge portion.
FIG. 17 shows still another embodiment.
FIG. 18 is a side sectional view showing a conventional decanter type device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bowl 2 Front end wall 3 Rear end wall 6 Drain port 7 Filtrate discharge port 8 Suppression ring 10 Screw conveyor 11 Rotating drum 12 Spiral blade 14 Supply chamber 15 Supply port 16 Supply pipe 17 Annular space 18 Suppression rod 19 Discharge port 20 Suppression ring 21 Ring portion 22 Mounting piece 23 Spacer 24 Mounting bolt 25 Filtrate discharge portion 26 Discharge hole 27 Screen 28 Scraping blade

Claims (7)

In a centrifugal dewatering device that houses a screw conveyor with spiral blades wound around its outer periphery that rotates with a relative speed difference in a high-speed rotating bowl, the bowl is directly connected to a horizontal cylinder with front and rear end walls. Formed in a barrel shape, the rear end wall of the bowl is provided with a separation liquid discharge port located in the vicinity of the outer periphery where the distance from the rotation center can be taken long. provided with a waste sludge outlet in the peripheral wall, the inner peripheral rear than the exhaust mud port, projecting suppression ring giving compaction dehydrated cake, and, towards the screw conveyor, in the rear of the bowl provided with a means for supplying a stock, the front outer periphery of the rotating cylinder of the screw conveyor, the projecting suppression ring and opposite to suppress flange, forming a narrow extrusion port therebetween suppression ring and the suppression flange and, nearest off by the spiral wing Is undergoing compaction by the suppression flange dehydrated cake which is conveyed to the suppression ring to the front of the bowl, characterized in that so as to be flow out into the exhaust mud port the is extruded from a narrow extrusion port A centrifugal dehydrator. 2. The centrifugal dewatering apparatus according to claim 1, wherein a suppression ring is provided so as to be able to advance and retreat in the length direction of the bowl so that the width of the discharge port can be adjusted. The centrifugal dewatering device according to claim 1 or 2, wherein the suppression ring and the suppression rod are formed in a cross-sectional mountain shape having a tapered rear end surface. The centrifugal dewatering device according to claim 1 or 2, wherein either one of the suppression ring and the suppression rod is formed in a mountain-shaped cross section having a tapered rear end surface and the other end is formed in an upright surface. . A filtrate discharge section comprising a separation liquid discharge hole and a filtration screen attached thereto is provided on the peripheral wall of the rear part of the bowl instead of the discharge port of the rear end wall of the bowl. 4. The centrifugal dehydrator according to 4. 5. In addition to a discharge port on the rear end wall of the bowl, a filtrate discharge part comprising a separation liquid discharge hole and a filtration screen attached thereto is provided on the peripheral wall of the rear part of the bowl. The centrifugal dehydrator as described. The centrifugal dewatering according to claim 5 or 6, characterized in that a spiral blade of the screw conveyor is cut out and a sludge scraping blade adhering to the screen of the filtrate discharge portion provided on the peripheral wall of the bowl is provided in that portion. apparatus.

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