JP2002239416A - Centrifugal separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the separation performance of a horizontal centrifugal separator and to make its energy consumption less and its cost lower. SOLUTION: A bowl 1 of the centrifugal separator constituted by housing a screw conveyor into the bowl 1 rotating at a high speed is formed to a straight cylindrical shape of a horizontal cylinder and its rear end wall 3 is provided with a discharge port 7 for a separating liquid C in its outer peripheral part and the inner periphery in the front part of the bowl 1 having a sludge discharging port 6 is projectingly provided with a suppressing ring 21. On the other hand, a rotary cylinder 11 of the screw conveyor 10 is provided with a supply port 15 for a stack solution (a) in its rear part and the front part of the rotary cylinder 11 is projectingly provided with a suppressing collar 23 toward the suppressing ring 21. A narrow discharge path 20 for filtered cake (b) is formed between the suppressing ring 21 and the suppressing collar 23. The suppressing ring 21 is provided with many projecting ribs 25 which project in the discharge path 20. As a result, heavy components (b) are subjected to the effect of compaction, extrusion, wringing, etc., by which a dewatering rate is eventually greatly improved. Since the degrees of separation of the heavy components in the discharge path 20 are eventually variously regulatable by changing the shape and arrangement, etc., of the projecting ribs 25, the adequate treatment corresponding to the characteristic of raw water is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a straight-body centrifugal separator in which the concentration, dehydration, and recovery of solids and separated water of sewage sludge and industrial wastewater are performed by centrifugal force. .

[0002]

2. Description of the Related Art Conventionally, a decanter-type centrifugal separator is generally used for solid-liquid separation of sludge and the like. As shown in FIG. 13, the separating device has a conical cylinder 41 in front of a horizontally long straight body portion 40.
A screw conveyor 10 provided with a spiral blade 12 on an inner cylinder (inner rotating cylinder) 11 in a bowl (outer rotating cylinder) 1 which is formed at a high speed and rotated with a relative speed difference from the bowl 1 And a stock solution a such as sludge is supplied from the inner cylinder 11 into the front and rear central portions of the bowl 1 to perform solid-liquid separation by centrifugal force. The heavy component b sedimented and separated by the centrifugal force in the bowl 1 is sequentially raked toward the front end by the spiral blade 12, and further subjected to the consolidation and dewatering action in the conical cylinder 41, so that the front end is removed. The separated liquid C is discharged from the mud outlet 6 to the outside of the machine, and the separated liquid C is supplied to the rear end wall 3 of the bowl 1 on the opposite side.
Is overflowed and discharged from a discharge hole 42 provided at the bottom.

In this decanter-type centrifugal separator, the filtrate is stored in the bowl 1, the filtrate is prevented from flowing out of the mud outlet 6 for discharging heavy components, and the beach and In order to raise the heavy components above the water level in the bowl and increase the drainage effect by the conical part called, the level (water level) equal to or higher than the separation liquid outlet 42
The feature is that a conical cylinder 41 whose front end is narrowed to a small diameter is required.

[0004]

The centrifugal separator of the decanter type has been developed for concentration and dehydration of crystals and the like in a liquid phase, but is different from sludge having different properties. If you try to use it for concentration and dehydration
The sludge sediment layer is paste-like and highly hydrophilic, and in order to enhance the solid-liquid separation performance, it is necessary to exert a strong consolidation effect so as to squeeze out water. In the above conventional decanter-type centrifugal separator, when the processing liquid a is supplied to the central part of the bowl 1, in the bowl straight body part 40 immediately after the supply, solid-liquid separation is performed by a high centrifugal force field (about 2000 to 3000G). However, in the bowl conical portion 41 from which the heavy component b is discharged, a phenomenon that the centrifugal force is weakened and the water content increases because the distance (diameter) from the rotation center is short is seen. In fact, in the apparatus shown in FIG. 13, it has been observed that the moisture content is lowest in the d portion near the boundary between the straight body portion 40 and the conical portion 41. Furthermore, in order to discharge heavy components, it is necessary to rise the conical part against strong centrifugal force, and even if you try to transport by a screw conveyor,
When the water content is low, co-rotation occurs due to frictional resistance, and heavy components are not discharged while remaining, but only sludge having a relatively high water content close to the rotation center of the straight body portion 40 tends to be discharged. Can be seen.

[0005] Further, since the heavy component b passes through a conical cylinder having a large inclination for discharging the water beyond the water level in the bowl, the heavy component b slips at this portion and the discharge becomes poor.
There is a disadvantage that the sludge is discharged from the separation liquid outlet 42 together with the separation liquid and the separation liquid becomes dirty. In addition, since the discharged heavy component having a relatively high water content close to the rotation center of the straight body portion 41 is discharged, the rotation of the bowl 1 is reduced in order to lower the water content of the discharged heavy component. It is a fact that the number is higher than necessary (about 2,000 to 3,000 rpm). Therefore, large power is required.

The present invention has been made to solve the above-mentioned problems in the decanter-type centrifugal separator. In the above-mentioned conventional centrifuge, the sludge is directly discharged from the d portion having the lowest water content. It is intended to obtain a centrifugal separator that can be drained. As a result, the separation efficiency can be improved by promoting the separation, the number of rotations of the bowl can be reduced, the power can be saved, and the apparatus can be simplified and downsized because it has no conical beach portion.

[0007]

In the separation apparatus of the present invention, the shape of the bowl as a whole is an oblong cylindrical straight body, and a discharge hole for separated liquid is provided in the rear end wall of the bowl. Thereby, the residence time of the heavy component can be extended, and the solid-liquid separation can be sufficiently performed. Further, in the device of the present invention, a suppression ring for consolidating the heavy component and a suppression flange facing the same are provided at the front end where the heavy component is discharged, and the inner periphery of the bowl having the highest pressure density is provided. In addition, heavy components can be taken out through a narrow discharge path, so that solid-liquid separation performance can be improved and stable heavy components can be obtained irrespective of the properties of the stock solution and the heavy components.

[0008] The above-mentioned suppressing ring is formed immediately before the mud hole at the front end of the bowl (left side in Fig. 1) so as to protrude in a substantially mountain-shaped section with a tapered rear surface. In addition, the suppression flange has an outer peripheral surface having a substantially parallel tapered surface facing the tapered surface of the suppression ring, and is formed to project in a substantially trapezoidal cross section, and between these tapered surfaces, an annular heavy component is formed. An ejection path is formed. And on the tapered surface of the suppression ring,
Further, a number of protrusions are provided that protrude into the discharge path and extend in the longitudinal direction of the bowl, so that the discharge path is an uneven discharge path along the longitudinal direction of the bowl. As a result, the heavy component sent to the front end of the bowl and condensed by the suppression ring and the suppression flange is pressed into a narrow discharge passage having more irregularities and is squeezed to be subjected to a dewatering action.

In addition, the above-mentioned ridge can be provided on the tapered surface of the suppression flange facing the suppression ring. Further, it may be provided so as to face both tapered surfaces of the suppression ring and the suppression collar. The ridges may extend in a direction parallel to the axis of the bowl or in a direction inclined (intersecting) with the axis. The ridges may be straight, curved, mountain-shaped, zig-zag. It is good also as a shape. Further, in the case where the ridges are provided on both the suppression ring and the suppression collar, both ridges may be provided with the inclination directions opposite to each other with respect to the axis.

[0010] In the apparatus of the present invention, a place for discharging the filtrate can be provided on the peripheral wall at the rear portion of the bowl.
A scraping blade for scraping off sludge adhering to the filtrate discharge section provided on the bowl peripheral wall may be provided.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show an embodiment of the apparatus of the present invention, FIGS. 5 to 8 show other embodiments of the heavy component discharge section, and FIGS. 9 to 12 show other embodiments of the separation liquid discharge section. It shows an embodiment.

1 to 4, reference numeral 1 denotes a high-speed rotating bowl (outer rotating cylinder), which has a horizontal cylindrical straight body shape, and has hollow shafts 4 at the center of both front and rear end walls 2, 3. 5 is protruded, is supported by a bearing (not shown), and is rotated at a high speed by a driving device. On the peripheral wall at the front end of the bowl 1, a plurality of mud holes 6 are spaced along the circumferential direction, and at the rear end wall 3 of the bowl 1, an outlet 7 for separated liquid is provided. I have. The outlet 7 is not shown, for example, but it is preferable that a plurality of fan-shaped outlets be provided in the circumferential direction, or that a number of small holes be provided along the outer peripheral portion of the rear end wall 3. .

Numeral 10 denotes a screw conveyor housed in the bowl 1 and a spiral wing 12 is wound around the outer periphery of a horizontal cylindrical rotating drum 11 and both ends thereof are connected to the hollow shafts 4 and 5 of the bowl 1.
The rotating shaft 13 is supported by a protruding portion inside the bowl and is rotated with a required speed difference from the bowl 1 by a rotating shaft 13 inserted through the hollow shaft 4. In the rear part of the rotating drum 11, a supply quality 14 of the undiluted solution a is provided, and a supply port 15 communicating with the annular space 8 between the bowl 1 and the rotating drum 11 is opened on the peripheral wall thereof. A space 16 between the supply of the undiluted solution inserted through the rear central shaft 5 of the bowl 1 is provided in the supply material 14.

A short discharge path 20 in the axial direction is provided in the front end of the bowl 1 for discharging the heavy component b conveyed in the annular space 8 while giving a compaction and a squeezing action. . That is, the front end of the bowl 1 is provided with a tapered surface 22 on the inner side immediately before the mud hole 6 (left side in FIG. 1).
A suppression ring 21 having a tapered cross-section that is formed in a substantially mountain shape is provided to protrude inward. In addition, screw conveyor 10
At the front end of the rotating body 11, a suppression flange that forms an annular discharge path 20 with the suppression ring 21 at a position facing the suppression ring 21.
23 are protrudingly provided, and as shown in FIG.
The outer periphery thereof is formed to have a substantially trapezoidal cross section as a tapered surface that faces substantially in parallel with the tapered surface 22 of the suppression ring 21, and the discharge path 20 is formed between the tapered surfaces 22 and 24.

Then, a tapered surface 22 on the inner periphery of the suppression ring 21
Are provided with a number of ridges 25 projecting into the discharge passage 20 and extending in the front-rear direction of the bowl 1 and parallel to the axis 0-0 (FIG. 3) at intervals in the circumferential direction. Thus, the inner periphery of the suppression ring 21 is formed on the tapered surface 22 having a large number of irregularities running in the axial direction. The ridge 25 is not limited to the one extending in parallel to the axis as described above. FIG. 4 shows various embodiments of the ridge 25. FIGS. 4 (a) and 4 (b)
The shape is inclined (intersecting) with respect to the axis 0-0. In (a), the direction of the inclination is inclined so as to follow the flow of the heavy component b due to the rotation of the spiral blade 12, and B) is inclined in the direction against the opposite flow.

Since the heavy component b is conveyed by the rotation of the spiral blade 12, it is pressure-fed even in the discharge path 20 while rotating in the same direction. Therefore, ridge 25
Depending on the inclination angle between the turning direction and the opposite direction, the resistance when passing through the discharge path 20 is changed, which is related to the degree of dehydration of the heavy component b. Therefore, it is preferable to set the inclined state of the ridge 25 according to the properties of the stock solution and the heavy component. Also, ridge 25
Can be applied to various shapes such as a curved shape as shown in FIG. 4 (C), a mountain-shaped bent shape as in (2), and a zigzag shape as in (E). .

FIGS. 5 and 6 show a suppression ring forming the discharge path 20. FIG.
13 shows another embodiment in which a portion provided with 21 and a suppressing flange 23 is shown. In this embodiment, the ridge 25 is provided not in the suppression ring 21 but in the tapered surface 24 of the suppression collar 23 so as to project into the discharge path 20. The consolidation and squeezing effects on the heavy component b are almost the same as in the previous embodiment. Also in this case, ridge 25
FIG. 3, which is described in the previous embodiment,
Each example in FIG. 4 can be applied.

FIG. 7 and FIG. 8 show the ridge 25 and the suppression ring 21 and the suppression flange.
23 shows an embodiment provided in both of them. The ridge 25 of the suppression ring 21 projects from its tapered surface 22 as in the embodiment of FIGS. 1 and 2, and the ridge 25 of the suppression ring 23 projects from its tapered surface 24. Again, the suppression ring
3 and 4 can be applied to both the protrusion 21 and the suppression rib 23.

Further, in the apparatus of the present invention, a place for discharging the filtrate may be provided on the peripheral wall of the bowl 1. 9 and 10 show the embodiment. In this embodiment, the rear end wall 3 is not provided with a discharge port, and instead, a discharge portion 30 for filtrate is provided on the peripheral wall at the rear portion of the bowl 1. As shown in FIG. 10, a large number of discharge holes 31 are formed along the circumferential direction, and a screen 32 made of a porous plastic molded body, a wire mesh, ceramic, sintered metal, a filter cloth, etc. Is attached. In addition, this filtrate discharge part 30
The structure is not limited to the above, and the discharge holes 31
The structure can be changed as appropriate as long as the combination is made with the screen 32 and the screen 32.

As described above, in the case where the discharge point of the filtrate is provided on the peripheral wall of the bowl 1, the separated liquid C is discharged immediately after the supply of the undiluted solution. Therefore, solid-liquid separation and dehydration are performed more efficiently.

Further, in the apparatus of the present invention, as shown in FIG. 11, the filtrate is discharged from the bowl rear end wall 3 as in the embodiment of FIG. 1 and the bowl 1 as in the embodiment of FIG. May be provided on the peripheral wall. That is, the discharge port 7 is provided on the rear end wall, and the filtrate discharge section 30 is provided on the peripheral wall of the bowl. By doing so, the discharge port 7 and the filtrate discharge section 30
Since the separation liquid C is discharged from both of them, it is possible to efficiently process sludge having a low concentration and high load.

FIG. 12 shows an embodiment provided with a means for scraping off the sludge adhering to the filtrate discharge part 30. That is, in this embodiment, toward the screw conveyor 10,
Corresponding to the filtrate discharge section 30, a part of the spiral blade 12 is cut out, and the tip of the rotary cylinder 11 is in sliding contact with the screen 32, and the scraping blade 33 of the sludge adhered to the screen 32 is cut off. Multiple are mounted radially. The scraper blades 33 not only scrape off the sludge adhering to the screen 32 but also maintain an angle with respect to the axis so as to have a conveying force for the sludge and the dewatered cake. Is preferred. Also,
In this embodiment, the outlet 7 is provided in the rear end wall 3 of the bowl 1, but the outlet 7 may not be provided.

The sludge adhering to the screen 32 of the filtrate discharge part 30 can be scraped to some extent by the spiral blade 12 of the screw conveyor 10. But spiral wings 12 and screen
Since there is a slight gap between the inner surface of the screw 32 and the rotation speed difference between the bowl 1 and the screw conveyor 10, the scraping by the spiral blade 12 is slow. Insufficient scraping results in clogging of the screen 32 and poor discharge of separated water. Therefore,
In the apparatus of this embodiment, the scraper blades slidingly contacting the screen 32
33 is provided so that the sludge can be scraped positively.

[0024]

As described above, according to the centrifugal separator of the present invention, the discharge part of the filtrate (separated liquid) is provided on the peripheral wall at the rear part of the bowl or the peripheral part of the rear end wall, and the undiluted liquid is filtered. The liquid is supplied into a bowl having a liquid discharge section (discharge hole), and a suppression ring and a suppression flange are provided opposite to the front end of the bowl and the front end of the rotary cylinder of the screw conveyor. Is provided, and a protruding ridge protruding into the discharge path is provided on one or both of the suppression ring and the suppression collar, so that many excellent effects are provided as follows.

(1) Since the bowl has a straight body shape and a suppression ring and a suppression flange are provided at a heavy component discharge portion, a long conical cylinder with a long inclination and a large aperture as in the conventional machine can be used. It is not necessary to install, and it is possible to smoothly transport and discharge heavy components having a low water content.

(2) The heavy component is condensed by the suppression ring and the suppression collar at the front end of the bowl, and passes through a discharge passage having a narrow unevenness formed by the suppression ring, the suppression collar, and the ridges. As a result, the material is further extruded and discharged by the squeezing action, so that the dewatering rate is greatly improved. Also, by changing the shape and arrangement of the ridges variously, it is possible to adjust the water content suitable for the properties of raw water and heavy components.

(3) In a device provided with a filtrate discharge portion on the peripheral wall, since filtration is performed by a screen, the properties of the separated water are good and the occurrence of a water surface in the bowl can be prevented. Yes, especially in devices equipped with sludge scraper blades.
The clogging of the screen can be prevented, and the operation efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment of the apparatus of the present invention.

FIG. 2 is a sectional view taken along the line II of FIG.

FIG. 3 shows an example of the shape and arrangement of ridges.

FIGS. 4A to 4E show other examples of the shape and arrangement of the ridges, respectively.

FIG. 5 is a side sectional view showing another embodiment of the heavy component discharging section.

FIG. 6 is a cross-sectional view taken along a roll line of FIG. 5;

FIG. 7 shows still another embodiment of the heavy component discharging unit.

FIG. 8 is a cross-sectional view taken along the line of the Haha in FIG. 7;

FIG. 9 is a side sectional view showing another embodiment of the filtrate discharge part.

FIG. 10 is an enlarged side sectional view of a filtrate discharge part.

FIG. 11 is a side sectional view showing still another embodiment of the filtrate discharge part.

FIG. 12 shows still another embodiment.

FIG. 13 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 Discharge port 7 Filtrate discharge 8 Annular space Screw conveyor Rotary drum 12 Spiral blade 14 Supply chamber supply port Supply pipe Discharge path 21 Suppression ring 22 Tapered surface 23 Suppression flange 24 Tapered surface 25 Ridge 30 Filtrate discharge part 31 Discharge hole 32 Screen

Claims (4)

[Claims] 1. A screw conveyor rotated at a relative speed difference is accommodated in a bowl rotated at a high speed, and heavy components are separated and settled by centrifugal force from a stock solution supplied into the rotating bowl. Is transferred to the front end of the bowl by a screw conveyor and discharged, the bowl is formed into a horizontal cylindrical straight body, a discharge hole for separated liquid is provided in the rear end wall of the bowl, On the inner periphery of the front end, a suppression ring that gives consolidation action to the heavy component is protruded, and at the front end of the rotating drum of the screw conveyor, a suppression ring is protruded facing the suppression ring, and the inner periphery of the suppression ring is The discharge path of the heavy component is formed between the outer circumference of the suppression collar and the uneven surface extending in the longitudinal direction of the bowl is provided on the opposing peripheral surface of one or both of the suppression ring and the suppression flange. And distant Heart separation device. 2. A liquid discharge part comprising a discharge hole for a separated liquid and a filtration screen attached thereto is provided on the peripheral wall at the rear part of the bowl instead of the discharge port on the rear end wall of the bowl. The centrifugal separator according to claim 1. 3. In addition to the outlet at the rear end wall of the bowl, the peripheral wall at the rear of the bowl is provided with a filtrate outlet comprising a discharge hole for separated liquid and a filtration screen attached thereto. The centrifugal separator according to claim 1. 4. The screw conveyor according to claim 2, wherein a spiral blade of the screw conveyor is cut out, and a scraper blade for sludge adhering to a screen of a filtrate discharge part provided on a peripheral wall of the bowl is provided in the notch. 4. The centrifugal separator according to 3.