JP4702607B2 - Continuous pressure dehydrator using sheet metal filter media - Google Patents

Description

This invention is a continuous process using a thin plate metal filter medium that pressurizes a stock solution such as sewage sludge, food waste surplus sludge, and human waste sludge into a disk-shaped filtration chamber, and concentrates and pressurizes and dewaters while circulating the impeller and stock solution. The present invention relates to an improvement of a pressure dehydrator.

  In Patent Document 1, a continuous pressure dehydrator in which a filtration chamber is formed by a disc-shaped filtration plate having a filtration surface made of a wedge wire and an outer ring of the filtration chamber, and a rotatable impeller is disposed in the filtration chamber is disclosed in Patent Document 1. The applicant of the invention has proposed. FIG. 15 is a conceptual diagram of a continuous pressure dehydrator, in which a plurality of receding blades 38a are slid on a disc-shaped filtration surface 37 whose interval does not change, and a wedge surrounded by the receding blades 38a and the filtration surface 37. In the shape area, a press-fitting pressure concentration zone A in the inner peripheral part, a (press-fitting pressure + blade concentrating) zone B in the intermediate part, and a vane pressing zone C in the outer peripheral part are formed, and the volume of the press part is expanded. is there. And the undiluted | stock solution press-fitted from the center part is extruded to the outer peripheral direction with the backward blade 38a, and a pressing action is generated by pushing into the wedge-shaped area enclosed by the backward blade 38a and the filtration surface 37. Filtration proceeds in the radial direction from the central portion of the filtration surface 37, and the conveying action of the continuous pressure dehydrator is generated by the impeller 38 with a delay angle, but the conveying action is performed at a stage where the moisture content of the sludge is high and the fluidity is high. Is not big. For this purpose, the press-fitting pressure of the stock solution is increased, and a desired transporting action is obtained in the inlet concentrating portion by a joint action of the press-fitting pressure pushing action and the impeller transporting action.

  As a filter for changing the hole diameter of the screen, a rotary compression filter in which a filter chamber is constituted by two freely rotatable screens fixed to an inner ring spacer and an outer ring spacer is described in Patent Document 2, for example. It is known. In this rotary compression filter, the filter screen hole of the rotatable screen is provided with a small hole of the same degree as the conventional one in the inner peripheral edge side zone, and the smaller hole in the outer peripheral edge side zone than the conventional one. The stock solution is introduced into the filtration chamber from the outer ring spacer, the treatment stock solution is moved and dehydrated by the frictional force of the two rotating screens, and the sectional area of the filtration chamber in the compression zone is gradually reduced. It is structured to be moved to the partition wall plate having a shape. Due to the action of the rotational frictional force of the screen, the dewatered cake in the squeezing zone moves toward the partition plate, the moisture content of the cake is lowered in the vicinity of the partition plate, and the moisture content of the cake is increased in the vicinity of the outer ring spacer facing it. The cake that has progressed to the squeezing zone moves the cake at the inner peripheral edge to the outer peripheral edge by the partition plate, and performs final solid-liquid separation on the screen surface of the outer peripheral edge to discharge the cake.

  Further, as a filter for changing the hole diameter of the screen, a screw press in which the hole diameter of the screen stretched on the outer cylinder is sequentially reduced from the supply side to the discharge side is also known as described in Patent Document 3. . FIG. 16 is a conceptual diagram of a screw press, in which a screw shaft 41 around which a screw blade 40 is wound is disposed on an outer cylinder 39 with a screen stretched, and the volume decreases in the discharge direction. A press-fitting pressure concentration zone a, an intermediate blade concentration zone b, and a discharge blade compression zone c are formed. While the inside of the filter cylinder in which the volume of the screw press is reduced, the stock solution supplied to the press-fitting pressure concentration zone a at the inlet portion is discharged from the blade concentration zone b at the middle portion while generating the pressing action by the feeding action of the screw blade 40. To the blade compression zone c.

JP 2004-167543 A (summary of front page, paragraph number 0014, and FIG. 5) JP 2001-113109 A (Claim 5, paragraph number 0015, paragraph number 0023 and paragraph number 0049, FIGS. 4 and 5) JP-A-4-15796 (Claim 1, paragraph number 0006, and FIG. 2)

  The metal filter medium used in the continuous pressure dehydrator of Patent Document 1 has a hole diameter, a slit width, a hole pitch, etc., regardless of the amount of filtrate to be discharged from the central part toward the outer peripheral part and the requirement for suppressing the amount of SS missing. The specifications are constant. Originally, the specifications of the metal filter medium suitable for the press-in pressure concentration zone A that discharges a large amount of filtrate at a low pressure and the blade press zone C that discharges a small amount of filtrate at a high pressure are different. Corresponding by selecting a filter medium having an intermediate specification in the compression zone C. The filter medium of this continuous pressure dehydrator has a constant hole diameter, and the medium diameter was selected within a range that would not be fatally deviated from the inlet and outlet conditions. Therefore, the processing amount is restricted by the concentration unit. Further, in the blade pressing zone C, there is a problem that the hole diameter is excessive, so that there are many openings and the recovery rate is deteriorated.

  In the rotary compression filter of Patent Document 2, since the hole diameter on the outer peripheral edge side of the inlet concentrating portion provided with small holes smaller than the conventional one is too small and the opening ratio is insufficient, the stock solution introduced into the filtration chamber is The throughput is restricted by the concentration section, and the solid-liquid separation effect is reduced in the filtration zone where the supply pressure is low. In the squeeze zone, the rotating disk-shaped screen moves the dewatered cake to the inner peripheral edge side of the partition plate, so that the cross-sectional area of the filtration chamber is gradually reduced. In the vicinity of the inner end portion of the partition plate in which the small holes are provided, the hole diameter is excessively large and the recovery rate may be deteriorated due to the excessive hole diameter in response to the request for suppressing the amount of the through SS. In the squeezing zone, the zone on the inner peripheral edge side is closed by the partition plate, and it becomes difficult to discharge the dewatered cake only with the rotational frictional force of the screen, and there is a risk of clogging. In the rotary compression filter, the rotating disk-shaped screen passes through the concentrate zone on the inlet side of the stock solution and the pressing zone on the cake outlet side, so the conventional small holes on the inner peripheral edge side and the outer peripheral edge side Small pores smaller than those of the conventional one cannot be assigned to the role of concentration or squeezing for each filtration zone or squeezing zone region of the filtration surface.

  The screw blade of the screw press of Patent Document 3 has the same transport function as a screw conveyor in the case where the transported material is filled and transported, and the filtration pressure applied to the inlet concentrating part is applied only for the initial concentration. There is a good advantage. In the continuous press dehydrator, the volume of the pressing part of the filtration chamber is enlarged, but in the screw press, it is reduced. Since the press-fitting pressure of the stock solution of the screw press may be low, there is an advantage that the pore diameter of the filter medium can be made larger than that of the continuous pressure dehydrator from the viewpoint of missing. The screw press shown in FIG. 16 has a single-sided filter medium structure when the screen stretched on the outer cylinder is developed. This difference is greatly affected by the difference in the filtration area, and the dehydration processing capacity per unit filtration area of the screw press is Inferior to continuous pressure dehydrator.

  The material processing method of the metal filter medium used in the above solid-liquid separator includes punching hole processing that is punching and cutting, wedge wire screen that welds the wedge wire in a lattice shape, drill hole processing that is cutting, or high energy input. Melting laser beam, electron beam, discharge hole machining, etc. With a punching metal, it is extremely difficult to change the diameter of fine holes penetrating in the thickness direction into an integral concentric ring. The method of joining parts with different pore diameters of the filter medium is unrealistic because the material to be discarded is remarkably large for the convenience of material collection. The wedge wire can be freely selected from a narrow slit width and a wire width, but it is extremely difficult to change the slit width partially in the wedge wire structure because of the structure of the wedge wire. As with punching metal, processing that combines concentric annular patterns is not impossible if a large amount of processing is applied, but it is more expensive than punching metal, including the fact that it is originally expensive and more materials are discarded due to material picking. In reality, it is not practical. In particular, punching metal and wedge wires cannot be used in the case of processing that continuously changes the hole diameter. In addition, drilling, which is cutting, can be applied to the production of small-diameter sheet metal filter media. However, because the machining speed is slow, large-diameter and large-diameter sheet metal filter media are extremely expensive, and can be used as a filtration surface for large and large-diameter processed parts. There is also a problem of distortion due to generated heat.

  Laser beam, electron beam, and discharge hole machining cannot be performed due to machine tool restrictions for large models of filter media having a diameter of φ1500 or more. Although it can be processed only for application to a relatively small model, it is expensive and there are restrictions on the application even in a case where the filter medium hole specification is constant. Laser beam, electron beam, and electric discharge machining can also be processed with a continuous change in hole diameter, but the basic principle is that the metal is heated and melted at high energy, so it is easily distorted due to residual thermal stress. Further, when the hole diameter or pitch is changed, the amount of strain also changes and the filter medium may swell, which is not preferable for a filter medium that requires flatness. In the present invention, a thin plate metal filter material for solid-liquid separation that changes micropores is produced in accordance with the demand for the amount of filtrate to be discharged from the inlet concentrating portion toward the outlet pressing portion, and the amount of SS being cut off. The present invention relates to an improvement of a continuous pressure dehydrator that uses a metal filter medium to greatly improve dewatering performance.

The gist of a continuous pressure dehydrator using a thin metal filter medium according to the present invention is that a disk-shaped filter plate having a pair of filtration surfaces, an annular filter chamber outer ring, and an inner ring support cylinder form a filtration chamber , A cake discharge port is provided in the liquid supply chamber and the outer ring of the filter chamber inside the ring support tube, and a rotatable impeller is provided in the filter chamber, so that the filtration proceeds from the center to the outer periphery of the filter chamber. In the pressure dehydrator, the fine holes of the thin sheet metal filter medium arranged in the filter plate are arranged in a concentric ring shape and the hole diameter is gradually reduced from the central part toward the outer peripheral part, and discharged from the central part toward the outer peripheral part. If the pore size and pitch of the fine metal filter medium are appropriately set according to the decrease in the filtrate amount and the increase in the filtration pressure, the amount of pass-through SS is suppressed, compared with the conventional filter media with a constant pore diameter. Dehydration is improved by increasing the amount and decreasing the water content. Since it is a fine hole penetrating in the thickness direction, clogging of the fine hole due to the stagnation of the solid does not proceed, and the filtration speed is not lowered and peeling failure does not occur.

  The thin plate metal filter used in the continuous pressure dehydrator is formed by dividing the thin plate metal filter medium into a plurality of concentric annular divided thin plate metal filter media, and gradually forming the fine holes of the divided thin plate metal filter media from the center toward the outer periphery. By reducing the size and adapting the appropriate pore size according to the progress of filtration, excessive omission can be prevented and the recovery rate can be improved. And the thin plate metal filter material divided into concentric rings is intended for low-concentration sludges such as food waste surplus sludge, and the thin plate metal filter material is divided into three concentric ring patterns, and the area of each divided thin plate metal filter material If the ratio is 2: 1: 1 from the central part toward the outer peripheral part, the pore diameter and the opening ratio of the inlet concentrating part are improved, and the treatment amount is not restricted by the concentrating part, and the water content is reduced. And SS recovery rate increases. In addition, the thin plate metal filter that divides the pattern into concentric rings step by step is divided into three concentric ring patterns for the high concentration sludge such as sewage mixed raw sludge The area ratio of the thin sheet metal filter medium may be 1: 1: 1 from the center toward the outer periphery.

Sheet metal filter media, those may be configured by dividing sheet metal filter media of a plurality of parts divided in the radial direction, part of the divided sheet metal filter media, of being miniaturized by division, stepwise annular It is easy to process fine holes with different hole sizes, and it is advantageous for changing the design of the hole pattern. And, it is possible to make a thin plate metal filter medium that does not divide the parts by providing fine holes in the material step by step, but it is possible to individually manufacture divided sheet metal filter media of multiple parts divided in the radial direction and connect by welding etc. If a disc-shaped sheet metal filter medium is used, mass production can be achieved at low cost. Moreover, if a non-porous region is provided in the side edge portion of the divided thin metal filter medium of parts, the divided thin metal filter medium of a plurality of parts can be easily connected by welding or the like.

In large-sized large-diameter thin sheet metal filter media, a thin sheet metal filter medium may be composed of a concentric annular shape and a divided thin sheet filter medium of multiple parts divided in the radial direction, and a non-porous region may be provided at the joint of the divided thin plate filter medium. By dividing a thin sheet metal filter medium with limited manufacturing dimensions into small parts, it becomes possible to manufacture even a narrow processing apparatus, and it becomes a filter medium for a large continuous pressure dehydrator. In addition, if the penetration direction cross section of the fine hole of the thin plate metal filter medium is formed in a conical shape, and the fine hole expands from the filtration chamber side toward the filtrate discharge side, the fine hole expands in the filtrate discharge direction. The characteristics of the metal filter medium that are not easily clogged are strengthened.

If the fine holes are processed by photoetching, the hole specification can be freely designed, and a finely drawn pattern can be continuously processed into a metal plate. Since photoetching is a hole processing by chemical corrosion, the surface of the thin sheet metal filter medium is smooth and does not bend, resulting in a filter medium requiring flatness. Further, a single photoetching master / mask can be used repeatedly, and can be manufactured by a flow operation at a low cost in a short time. It is possible to intervene another pattern in the manufacturing process, and relatively small lots can be produced at low cost.

The continuous pressure dehydrator using the thin sheet metal filter medium according to the present invention is configured as described above, and the continuous pressure dehydrator responds to the filtration that proceeds from the center of the disk-shaped filtration surface toward the outer periphery. Since the pore diameter and pitch of the filter medium are adapted to a concentric ring shape, the amount of sludge treatment is increased and the moisture content of the cake is reduced and the dewaterability is improved as compared with a conventional filter medium having a constant pore diameter. And, by adapting the appropriate pore size according to the progress of filtration, it is possible to prevent excessive clogging, improve the recovery rate, and exhibit the characteristics of a sheet metal filter medium that is difficult to clog. Moreover, it becomes a filter medium of a large continuous pressure dehydrator by dividing a disk-shaped thin metal filter medium into a plurality of parts.
In addition, if the fine holes of the thin metal filter plate are processed by photoetching, it is possible to design a design with free holes continuously. Photoetching is a hole that is caused by chemical corrosion. The cross section can be formed in a conical shape.

The continuous pressure dehydrator using the thin metal filter medium according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view of the continuous pressure dehydrator according to the present invention, and a pair of disk-shaped filter plates. 1 and 1, an annular filter chamber outer ring 2 is connected to the outer peripheral end thereof, and an inner ring support tube 3 is connected to the inner peripheral end, and an annular filter chamber 4 is formed between the pair of filter plates 1 and 1. It is. Filter plate spacers 5 and 6 are connected before and after the inner ring support cylinder 3, and a liquid supply chamber 7 is formed inside the inner ring support cylinder 3 therebetween. An undiluted solution supply pipe 8 supported on one filter plate spacer 5 is open to the supply chamber 7, and a bearing 9 fixed to the other filter plate spacer 6 is connected to a frame 10. A drive shaft 11 pivotally supported by a bearing 9 of the filter plate spacer 6 extends to the liquid supply chamber 7, and an impeller 12 disposed in the filtration chamber 4 is fixed to the drive shaft 11. A drive machine 13 disposed on the frame 10 is linked to the rear end of the drive shaft 11 so that the impeller 12 is rotatable.

FIG. 2 is a front view of a thin metal filter medium disposed on the filtration surface of the filter plate. A thin metal filter medium 14 penetrating in the thickness direction is disposed on the filtration surface of the filter plate 1, and the outer frame 15 and the inner The frame 16 is fixed. FIG. 3 is a vertical cross-sectional view of the fine holes of the thin metal filter medium. The thin metal filter medium 14 has a large number of fine holes 17 having a conical cross section in the penetration direction, and the filtration chamber side. It is expanded toward the filtrate discharge side. The micropores 17 expand in the direction of discharge of the filtrate, and the characteristic that the metal filter medium is difficult to clog is enhanced. The micropores 17 arranged in the filter plate 1 shown in FIG. 2 are arranged concentrically in an annular shape, and the pore diameter is gradually reduced from the central portion toward the outer peripheral portion.
FIG. 4 is a rear view of the filter plate, and a reinforcing punching metal 18 is disposed on the back surface of the thin metal filter medium 14 stretched on the filter plate 1, and the punching metal 18 is connected to the outer frame 19 and the inner frame 20. The filter plate 1 is fixed to the filter plate 1 with a reinforcing frame 21 fixed to the plate. The filter plate 1 is composed of a thin metal filter medium 14, a punching metal 18, and a reinforcing frame 21.

  FIG. 5 is a front view of the filtration chamber in which the impeller is arranged. The side edge of the impeller 12 is slid on the thin metal filter medium 14 of the filtration plate 1 and its tip is brought close to the filter chamber outer ring 2. is there. Note that a flexible scraper may be fixed to the side edge of the impeller 12 and slid on the thin metal filter medium 14. In the embodiment of the present invention, the blade 12a of the impeller 12 is bent into five straight pieces to approximate a curved line, and is moved backward in the rotational direction. A supply path for the stock solution is provided between the plurality of reinforcing ribs 22 attached to the blades 12a on the rear surface in the rotational direction of the impeller 12, and the stock solution is press-fitted into the feed chamber 7 from the feed pipe 8 to The directional filtration chamber 4 is made to uniformly flow from the left and right of the reinforcing ribs 22 of the impeller 12. The stock solution transport action is generated by the impeller 12 with a lag angle, but the transport action is not large at the stage where the water content of the sludge is high and the fluidity is high. For this purpose, the press-fitting pressure of the stock solution is increased, and a desired transporting action is obtained by the joint action of the press-fitting pressure pushing action and the impeller 12 transporting action in the inlet concentrating section.

  5 and 15, the sludge that is press-fitted from the center is pushed outward by the blade 12 a at the base end, and pushed into the wedge-shaped area surrounded by the blade 12 a and the thin metal filter media 14, 14. Then, the squeezing action is generated, and the filtrate is separated from the fine holes 17 of the thin metal filter medium 14 and concentrated and dehydrated. The blade 12a of the impeller 12 rotates while sliding on the filtration surface of the filter plate 1, scrapes the cake layer formed on the filtration surface, and regenerates the filtration surface of the thin metal filter medium 14 while conveying the cake. In the vicinity of the filter outer ring 2, the rotational wedge action of the blades 12a and the force that causes the cake to bend and flow in the radial direction increase, a large shearing force is applied to the cake, and the moisture content of the cake decreases. As shown in FIG. 5, a cake discharge port 23 provided in the outer ring 2 of the filter chamber is disposed laterally downward, and the cake that has been squeezed and dehydrated is discharged from the discharge port 23. FIG. 6 is a front view of a continuous pressure dehydrator, and a flap valve 25 that is opened and closed by an air cylinder 24 is provided at the discharge port 23, and the opening degree of the discharge port 23 of the filtration chamber 4 is adjusted, A pressure is applied to the stock solution in the filtration chamber 4. Reference numeral 26 denotes a support for supporting the filter plate 1.

  The filtration surface of the thin metal filter medium 14 shown in FIG. 2 is formed by concentrating an annular hole in a thin metal plate made of stainless steel or the like, arranged in a concentric ring shape, and gradually reducing the hole diameter from the center to the outer periphery. Many fine holes 17 are arranged. The photo-etching processing steps are as follows. B. apply photosensitive resin to metal surface; B. exposure to light through an original plate (mask) to cure the resin; D. Wash away uncured resin that was developed and not exposed to light, leaving an original pattern of photosensitive resin; E. The part where there is no photosensitive resin melts as shown in the original drawing by the etching process. It consists of a flow operation of peeling and cleaning the photosensitive resin. Photoetching master / mask is designed by drawing from CAD drawing, and the same pattern used for mask can be processed into metal plate. One original / mask can be used repeatedly, and can be manufactured at low cost in a short time even in mass production. This flow work process can be mixed with another pattern, and is inexpensive even in the production of a relatively small lot.

  In the hole processing by photoetching, the fine holes 17 of the thin metal filter medium 14 can be formed into a desired shape such as a circle, an ellipse, a square, etc., and the hole diameter can be changed stepwise or continuously. Precise and finely drawn master / mask patterns can be processed as they are. Since photoetching is a hole processing by chemical corrosion, it becomes a filter medium that requires flatness without distortion, and a smooth filtration surface can be formed even with a large and large-diameter thin sheet metal filter medium 14. The hole processing by photo-etching can be processed in a conical circular shape or a fan shape by easily processing the cross section in the penetrating direction into a conical shape.

  In the continuous pressure dehydrator, the filtration surface of the disk-shaped thin sheet metal filter medium 14 is squeezed and dehydrated in the radial direction from the center, so that the amount of filtrate to be discharged from the center toward the outer periphery and If the hole diameter and pitch of the fine holes 17 provided in the thin plate metal filter medium 14 are appropriately set according to the request for suppressing the amount of SS removed, a large number of fine holes 17 provided in the thin plate metal filter medium 14 are arranged in a concentric ring shape. The hole diameter can be reduced gradually or stepwise from the central portion toward the outer peripheral portion. Compared with a conventional filter medium having a constant pore diameter, the processing amount is increased and the dehydrated moisture is reduced, and the amount of open SS is suppressed and the dewaterability is improved. And since it is the fine hole 17 which the surface of the sheet metal filter medium 14 was smooth and penetrated in the thickness direction, clogging of the fine hole due to the stagnation of the solid matter does not proceed, and the filtration speed does not decrease and the separation failure does not occur. The thin metal filter medium 14 is easy to clean, and the amount of water may be extremely small, and clogging due to precipitation solidification is greatly prolonged. Even if it is clogged, it is a hole that penetrates in the thickness direction, so chemical cleaning or jetter cleaning is effective. Further, the thin plate metal filter medium 14 can be applied to high temperatures, solvents, etc., has no deterioration, has a long life, and can easily remove dirt, so that material recycling is also possible.

  FIG. 7 is a front view of a thin plate metal filter medium that divides a concentric annular pattern stepwise, and a thin plate metal filter medium 27 is formed into a plurality of concentric ring divided thin plate metal filter media 27a, 27b, and 27c. The fine holes 17 of the metal filter media 27a, 27b, and 27c are gradually reduced from the central portion toward the outer peripheral portion. In the embodiment of the present invention, the fine holes 17 in the inlet concentrating part have a hole diameter of φ0.4 to 0.7 mm and an opening ratio of about 20%, and the filtration area of the inlet concentrating part is about ½ of the whole. , At least 1/3 or more. Moreover, although the amount of filtrate falls sharply compared with an inlet part, since an outlet pressing part also has a large amount of filtrates for double-sided filtration, the opening ratio is 10% in consideration of double-sided filtration. The pore diameter, pitch, and filtration area are set according to the sludge concentration and the processing amount of the stock solution, but if an appropriate pore diameter is adapted according to the progress of filtration, excessive omission can be prevented and the recovery rate is improved.

  In the embodiment shown in FIG. 7, low-concentration sludge such as food waste surplus sludge is symmetric, and the thin plate metal filter medium 27 is divided into three concentric annular patterns, and the thin plate metal filter medium is divided into thin plate metal filter media 27a and 27b. , 27c from the center toward the outer periphery, the hole specification is divided into a divided sheet metal filter medium 27a of the inlet concentrating part φ0.6mm, the divided sheet metal filter medium 27b of the intermediate filtration part is φ0.4mm, and the outlet compressed part is divided Thin metal filter media 27c are arranged in a diameter of 0.25 mm. And the area ratio of each division | segmentation thin plate metal filter medium 27a, 27b, 27c is set so that it may become 2: 1: 1 toward an outer peripheral part from a center part. The area of the divided sheet metal filter medium 27a that discharges a large amount of filtrate at a low pressure in the press-fitting pressure concentration zone A in the inner peripheral portion shown in FIG. 15 is increased, and at the same time, the hole diameter of the fine holes 17 is increased. The hole diameter of the divided sheet metal filter medium 27c in the blade pressing zone C at the outer peripheral part is made smaller than the filter medium specification of the divided sheet metal filter medium 21b in the zone B (press-fit pressure + blade concentration). By matching the appropriate area and hole diameter of the divided thin plate metal filter media 27a, 27b, 27c, the hole diameter and the opening ratio of the press-fitting pressure concentration zone A are improved, and the throughput is not restricted in the concentration step. Increase and decrease moisture content. In the blade pressing zone C, the hole diameter of the divided sheet metal filter medium 27c is reduced, the rotational wedge action of the blade 12a and the force of bending and flowing the cake in the radial direction are increased, and even if a large shearing force is applied to the cake, excessive mesh Omission is prevented and SS recovery rate increases. In addition, if an annular non-porous region 27d is provided at the boundary between the divided thin metal filter media 27a, 27b, and 27c that divide the thin metal filter media 27 into concentric rings, it is effective for changing the design of the hole pattern.

  FIG. 8 is a front view of another embodiment of the sheet metal filter medium that divides the pattern into concentric rings. In the embodiment of the present invention, it is intended for high-concentration sludge such as sewage mixed raw sludge. The pattern of the thin plate metal filter media 28a, 28b, 28c of the thin plate metal filter media 28 that divides the pattern in stages in a ring shape is specified from the center to the outer periphery, and the divided thin plate metal filter media 28a of the inlet concentrating portion is φ0. 7 mm, the divided sheet metal filter medium 29b of the intermediate filtration part is arranged to φ0.5 mm, the divided sheet metal filter medium 28c of the outlet pressing part is arranged to φ0.3 mm, and the area ratio of the divided sheet metal filter medium is set to 1: 1: 1 is there. The amount of processing is restricted at the inlet concentrating part, fine particles are not missed in the outlet pressing part, and the recovery rate is not deteriorated. In addition, the division of the patterns of the thin metal filter media 27 and 28 can be made by appropriately selecting the area ratio and the hole diameter by increasing or decreasing the number of steps of the pattern to be divided according to the properties of the processing stock solution and the size of the thin metal filter media 27 and 28. Is.

FIG. 9 is an embodiment of a divided sheet metal filter medium of fan-shaped parts,
Concentric annular porous zones A, B, and C are formed in three stages from the central part to the outer peripheral part of the divided thin metal filter medium 29 that has been subjected to hole processing by photoetching in the fan-shaped parts. The pore diameters of the porous zones A, B, and C are gradually reduced from the central portion toward the outer peripheral portion. The divided thin plate metal filter medium 29 can be mass-produced at a low cost with the same master / mask, and can also be manufactured by a flow operation. The divided thin metal filter medium 29 can be easily processed into fine holes step by step with the same original plate / mask, and is advantageous for changing the design of the hole pattern. As shown in FIG. 9, if the non-perforated area 29a is provided in the side edge part of the division | segmentation thin plate metal filter medium 29, the division | segmentation thin plate metal filter media 29a ... will be easily connected by welding etc. FIG. 10 shows another embodiment of the thin plate metal filter medium, in which the divided thin plate metal filter media 29... Of four fan-shaped parts are arranged in an annular shape, and the side edges of the divided thin plate metal filter media 29. Are joined by welding or the like to form a thin metal filter medium 30. If the manufacturing method of the part divided | segmented into the radial direction is used, since the division | segmentation thin plate metal filter medium 29 is small, it can manufacture by a flow operation also with a narrow photoetching processing apparatus, and becomes an inexpensive filter medium.

  FIG. 11 shows an embodiment of a semi-annular part split sheet metal filter medium, in which a semi-annular part split sheet metal filter medium 31 is provided with concentric annular porous zones A ′ and B ′ on the inner and outer peripheral parts. It is formed. The pore diameter of the fine holes 17 is reduced from the porous zone A ′ to the porous zone B ′, and a non-porous region 31 a is provided at the side edge in the radial direction of the divided thin plate metal filter medium 31. FIG. 12 shows another embodiment of the thin plate metal filter medium, in which two semi-annular divided thin plate metal filter media 31 and 31 shown in FIG. The thin plate metal filter medium 32 is configured by joining the hole areas 31a and 31a by welding or the like.

  FIG. 13 shows an embodiment of a thin plate filter medium divided into thin plate metal filter parts. The fan-shaped split thin plate metal filter medium 33 is further divided into a split thin plate filter medium 34 at the inner periphery and a split thin plate filter medium 35 at the outer periphery. It is divided into parts, non-porous regions 34a, 35a at the fan-shaped side edges of the divided thin plate filter media 34, 35, and non-porous regions 34b at the joint between the inner and outer peripheral divided thin plate filter media 34, 35. , 35b are provided. FIG. 14 shows another embodiment of the thin plate metal filter medium, in which the divided thin plate filter medium 34 on the inner peripheral part of the part and the divided thin plate filter medium 35 on the outer peripheral part shown in FIG. The non-porous regions 34a, 34b, 35a, 35b,... Of the filter medium 34 and the thin plate filter medium 35 at the outer peripheral portion are joined by welding or the like to constitute the thin plate metal filter medium 36. Photo-etching is also limited in manufacturing dimensions as in other processes, but by dividing a disk-shaped filter medium into several parts in the radial direction and the circumferential direction, mass production can be performed at low cost with a small master / mask. The drilling process, which is cutting, is suitable for the production of a small and small-diameter thin sheet metal filter medium 14. The small and small-diameter thin sheet metal filter medium 14, the small-diameter part split thin-plate metal filter medium 29, and the split thin-plate filter mediums 34 and 35. Can be applied.

  First, we examine the effects based on the difference in structure between the screw press that gradually reduces the filter media pore diameter of the outer cylinder and the sheet metal filter media of the continuous pressurization dehydrator. Considered. As shown in FIG. 16, the screw press has a structure in which the screw rotates in the axial direction in the filtration chamber whose volume decreases in the discharge direction, and the compression action is generated by forcibly reducing the volume by the feeding action. . In the screw press, the inlet concentrating part has a relatively large pore size / large opening ratio and the outlet pressing part has a relatively small hole diameter / small opening ratio in accordance with a decrease in the amount of filtrate to be discharged and an increase in filtration pressure. It is. The screw press has the same transport function as the screw conveyor, and the filtration pressure applied to the inlet concentrating part only needs to act for the initial concentration, and since the pressure is low, the pore size of the filter medium is Can be larger than a continuous pressure dehydrator.

  On the other hand, the blade shape of the continuous pressure dehydrator is as shown in FIG. 15, in which sludge press-fitted from the center of a disk-shaped filtration chamber whose interval does not change is pushed backward by a plurality of receding blades and moved backward. The squeezing action is generated by pushing into the squeezing part where the wedge-shaped volume surrounded by the blades and the outer periphery expands. The conveying action of the continuous pressure dehydrator is generated by an impeller with a delay angle, but the conveying action is not great at a stage where the moisture content of the sludge is high and the fluidity is high. For this purpose, the press-fitting pressure of the stock solution is increased, and a desired transporting action is obtained in the inlet concentrating portion by a joint action of the press-fitting pressure pushing action and the impeller transporting action. The pore size of the filter medium must be selected smaller than that of the screw press so that the number of voids does not increase even at high filtration pressure at the inlet concentration section. Therefore, the pore diameter of the filter medium in the inlet concentration section of the continuous pressure dehydrator is selected to be significantly smaller than that of the screw press. Specifically, it is less than half of the screw press φ1 to 2 mm and about φ0.4 to 0.7 mm.

  In the screw press, filtration proceeds in the axial direction on the cylindrical filtration surface of the outer cylinder, and the filtration area and shape of the outer cylinder do not change. On the other hand, the continuous pressure dehydrator has a disk-shaped filtration surface, and filtration proceeds in the radial direction from the center. The continuous pressure dehydrator has a different structure and operation from the screw press unless the pore diameter is gradually reduced in response to the demand for the amount of filtrate to be discharged from the center to the outer periphery and the amount of SS being suppressed. A sufficient effect cannot be obtained. The screw press has a single-sided filter medium structure, and the dewatering capacity per unit filtration area of the screw press is inferior to that of a continuous pressure dehydrator. The actual performance value of the filter medium at the inlet concentration part of the screw press is about 20% of the opening ratio. On the other hand, the continuous pressure dehydrator is double-sided filtration and has a high dewatering capacity per unit filtration area. It is necessary to increase the initial concentration function and distribute the processing amount so as not to be constrained at the entrance.

  According to the decrease in the amount of filtrate to be discharged and the increase in filtration pressure, the idea that the inlet concentrating part has a relatively large pore size / large opening ratio and the outlet compressed part has a relatively small hole diameter / small opening ratio is As in the case of the continuous pressure dehydrator, the corresponding area is remarkably enlarged. Therefore, unlike the screw press, the setting of the arrangement of the distance from the inlet (center) and the hole diameter is a filtration that expands in this fan shape. If an appropriate allocation according to the surface shape is set, a large performance improvement can be achieved as compared with a filter medium having a constant hole specification. Specifically, it is preferable to divide and allocate each process from the inlet concentrating part to the outlet pressing part into a concentric ring shape on the basis of area. If the continuous pressure dehydrator has a high aperture ratio, for example, a hole diameter of φ0.4 mm and a pitch of 0.6 mm, the aperture ratio will be 40%, but the size of the remaining part will be too small, causing problems such as strength or catching of fibrous materials. There is no adoption. A pore diameter of 0.4 mm, a pitch of 0.85 mm, and an aperture ratio of about 20% are the limits that can be adopted. In practice, it is difficult to increase the aperture ratio, and the area of the initial concentration zone is increased. Although it varies depending on the sludge concentration and the amount of treatment, the inlet concentration zone is specifically required to be about 1/2 of the whole, at least 1/3 or more. Moreover, although the amount of filtrate falls sharply compared with an inlet part, since an outlet pressing part also has a large amount of filtrate for double-sided filtration, it is necessary to ensure an opening ratio as it is. Although it is not necessary to increase the aperture ratio unnecessarily from the viewpoint of preventing omissions and securing the recovery rate, it is necessary to ensure an aperture ratio of 10% in consideration of double-sided filtration.

  Next, regarding the material processing method suitable for the sheet metal filter medium of the continuous pressure dehydrator, the pore size of the inlet concentrating part and the outlet pressing part and the manufacturing problems for executing concentric annular allocation were examined. As a material processing method of the filter medium, A. B. Punching hole processing that is punching and cutting; Drill hole machining, which is cutting, C.I. Laser beam, electron beam, discharge hole machining, which is melting by high energy input, There is a photo-etching hole processing in which the hole processing principle is chemical corrosion. The possibility of applying the present invention to the filter medium was examined with respect to hole processing technology, concentric annular allocation, and split manufacturing and joining. Punching metal is a conventional filter medium with a constant hole diameter, but if the hole diameter is less than φ0.4, a material with a width of 1000 mm or more is not available, so it is difficult to apply to φ1000 or more. In fact, it is not adopted. A small continuous pressure dehydrator having a diameter of about 200 mm can be adopted, but if it becomes a large continuous pressure dehydrator having a diameter of about 1500 mm, it is almost impossible to implement. Joining the concentric rings divided into concentric circles requires punching from a square-shaped material into a circular shape and further removing the inner side of the concentric annular shape for the convenience of material collection. The material to be discarded is extremely large and unrealistic. In punching metal, it is very difficult to change the hole diameter stepwise in a concentric ring shape. It is theoretically possible to program with a single punch, but it takes a lot of time. Punching metal that is normally distributed is punched with about two rows of punch dies over the entire processing width. Therefore, even if the punch die is specially designed, the punching machine structure cannot be used for annular punching.

  A wedge wire with a constant filter medium hole specification can secure a relatively high opening ratio of 20% when the slit width is 0.3 mm and the wire width is 1.5 mm, for example, and can be processed up to about 1500 width. Therefore, it is extremely difficult to change the slit width because of the structure of the wedge wire. As with punching metal, it is not possible to combine concentric rings that have been processed into enormous amounts of processing, but it is expensive in nature and more material is discarded due to material picking, making it more practical than punching metal. The nature is low. Particularly, a punching metal and a wedge wire cannot be used as a filter medium that continuously changes the hole diameter. Drilling, which is a cutting process, is very expensive for large and large-diameter thin sheet metal filter media because of its slow processing speed, and there is a problem of distortion due to heat generated on the filtration surface of a large and large-diameter processed part. In the case of a thin metal filter medium, it is possible to process the pore diameter that is reduced stepwise and to make the cross section into a conical diameter.

  As a processing technique of the filter medium that continuously changes the hole diameter, there are an electron beam, a laser beam, an electric discharge process, a photo-etching process, etc. Machining is impossible due to machine tool restrictions. Although it can be applied to relatively small models, there are limitations such as high production costs. Laser beam, electron beam, and electric discharge machining can in principle be used to continuously change the hole diameter if the input energy is program-controlled. However, the basic principle is that the metal is heated and melted at high energy, so the residual thermal stress is reduced. Therefore, it is easy to distort, and when the hole diameter and pitch are further changed, the amount of distortion also changes and the filter medium may swell. This is an undesirable phenomenon for a filter medium of a continuous pressure dehydrator requiring flatness. Although it is possible to apply it to a small model if the filter medium has a stepwise concentric annular hole diameter change, all of them are expensive dedicated machine tools that must be processed one by one and are extremely expensive. When producing, unless it has too many machine tools, it takes a long time to manufacture.

  Photo-etching can be processed into a metal plate with the same pattern used for the mask, so a very finely drawn pattern can be processed as it is. Since the original plate / mask is designed by drawing from a CAD drawing, the hole diameter can be divided into a desired shape such as a concentric ring shape or a fan shape, and the hole diameter can be easily changed stepwise or continuously. This photo-etching process includes A. B. apply photosensitive resin to metal surface; B. exposure to light through an original plate (mask) to cure the resin; D. Wash away uncured resin that was developed and not exposed to light, leaving an original pattern of photosensitive resin; E. The part where there is no photosensitive resin melts as shown in the original drawing by the etching process. This is a flow work of peeling and cleaning the photosensitive resin. A single photoetching master / mask can be used repeatedly and can be manufactured at a low cost in a short period of time even in mass production. It is possible to intervene another pattern in this flow work process, and even relatively small lot production is not expensive. Photoetching has some restrictions on the processing size, but even in the case of a filter medium for the maximum size φ1500 of continuous pressure dehydrator, the width of a normal photoetching line ( Many of them can be sufficiently processed at 600 mm or less). If the continuous pressure dehydrator φ500 is small, it can be integrated, and if it is about φ700 or φ1000, it can be divided into two in the diameter direction.

  For the reasons described above, the hole processing by photoetching can be freely designed, and the hole processing by chemical corrosion provides a fine pore filtration surface without distortion, which is the most excellent satisfying the requirements of the hole diameter of the present invention. Is the method. Photo-etching is also limited in manufacturing dimensions as in other processes, but it can be made inexpensively with the same master / mask by dividing the disk-shaped filter medium in the radial direction or by dividing it into several in the radial and circumferential directions. Mass production is possible. The hole processing by photoetching can be circular, oval, or slit hole diameter, and the cross section in the penetrating direction can be processed into a conical shape.

  Based on the above considerations, a continuous pressure dehydrator that uses a sheet metal filter that reduces the hole specification from the center to the outer periphery, and a continuous pressure dehydrator that uses a sheet metal filter with a fixed hole specification, A comparison experiment of the dewatering performance by the difference of the hole specification was done by specifying the stock solution of wastewater surplus sludge and raw sludge mixed raw sludge. As the continuous pressure dehydrator, a testing machine having an annular thin sheet metal filter φ700 × 2, a filtration chamber thickness of 50 mm, and a filtration area of 1.3 m 2 was used. The thin plate metal filter used in the experiment consists of a case A: a conventional thin plate metal filter with a constant pore diameter of 0.4 mm and a case B: a thin plate metal filter divided from the center to the outer periphery. On the other hand, a sheet metal filter medium in which the hole specification is an inlet concentration part = 0.6 mm, an intermediate filtration part = 0.4 mm, an outlet compression part = 0.25 mm, and the area ratio of the divided sheet metal filter medium is 2: 1: 1. used. The undiluted solution used in the experiment was added to the wastewater surplus sludge with a sludge concentration of 1.0% with a polymer flocculant addition rate of 1.2%, and this undiluted solution was pressed into the inlet concentration section of the filtration chamber at a pressure of 35 kPa. I went there. The results are shown in Table 1. The sheet metal filter medium that gradually reduces the fine pores of the case B used in the present invention has a 29% increase in the filtration speed compared with the sheet metal filter medium of the case A in which the pore diameter of the conventional filter medium is constant. It can be seen that the rate dropped by 2 points and the SS recovery rate increased by 13 points.

  Next, the area ratio of the pattern of the divided sheet metal filter medium was changed, and an experiment was performed using the above tester. The thin plate metal filter used in the experiment consists of a case A: a conventional thin plate metal filter with a fixed pore diameter of 0.5 mm, and a case B: a thin plate metal filter divided from the center to the outer periphery. On the other hand, use a thin plate metal with a pore specification of inlet concentrating part = 0.7 mm, intermediate filtering part = 0.5 mm, outlet pressing part = 0.3 mm, and the area ratio of the divided thin metal filter medium is 1: 1: 1 did. The stock solution used in the experiment was prepared by adding a polymer flocculant addition rate of 0.8% to sewage mixed raw sludge having a sludge concentration of 3.0% and press-fitting the stock solution into a filtration chamber at a press-in pressure of 30 kPa. The results are shown in Table 2. The thin plate metal filter medium that gradually reduces the fine pores of the case B used in the present invention has a 40% increase in filtration speed and moisture content as compared with the thin plate metal filter medium of the case A in which the pore diameter of the conventional filter medium is constant. It can be seen that SS decreased by 3 points and SS recovery increased by 5 points.

  From the above experimental results, in the continuous pressure dehydrator, the filtration proceeds from the center of the disc-shaped filtration surface toward the outer periphery, but if the pore diameter and pitch of the filter medium are adapted to a concentric ring according to the progress of filtration. It can be seen that the dewaterability is improved by increasing the treatment amount or decreasing the dehydrated water as compared with the filter medium having a constant pore diameter. Furthermore, excessive pores can be prevented by adapting the appropriate pore size according to the progress of filtration, and the recovery rate is improved. Furthermore, if hole processing by photoetching is used, the hole specification can be freely designed and the hole diameter can be designed continuously. If the manufacturing method is to divide the disk-shaped filter medium in the radial direction, or to manufacture by dividing the disk-shaped filter medium in the radial direction and the circumferential direction, each divided thin plate metal filter medium is small, so even in narrow photoetching processing equipment This makes it possible to provide inexpensive filter media. Originally, thin metal filter media with fine through-holes are difficult to clog and easy to clean, but photoetching can make the hole cross-section conical, so the small pore diameter side is the filtration surface and the large pore diameter side is the filtrate discharge side. In addition, these properties are further enhanced.

The continuous pressure dehydrator using the thin plate metal filter medium according to the present invention is arranged in a concentric ring shape with the fine holes of the thin plate metal filter medium stretched on the filter plate, reducing the hole diameter from the center toward the outer periphery, and filtering. Since the proper pore size was adapted according to the progress of the filter, the dewatering performance such as filtration speed, moisture content, SS recovery rate, etc. was greatly improved compared with the conventional thin plate metal filter media with a constant pore size. In addition, the continuous pressure dehydrator that increases the throughput of the stock solution and lowers the moisture content of the cake and improves the recovery rate.
Therefore, it becomes a dehydrator that concentrates and dehydrates stock solutions such as sewage sludge, food waste surplus sludge, and human waste sludge.

1 is a longitudinal sectional view of a continuous pressure dehydrator according to the present invention. Similarly, it is a front view of the sheet metal filter medium stretched around the filter plate. Similarly, it is a longitudinal cross-sectional view of the fine hole of a sheet metal filter medium. Similarly, it is a front view of the punching metal for reinforcement arrange | positioned on the back surface of a filter plate. Similarly, it is a side view of a filtration chamber provided with an impeller. Similarly, it is a side view of a continuous pressure dehydrator. Similarly, it is a top view of the thin metal filter medium which divides | segments a pattern into a concentric ring. Similarly, it is a top view of the sheet metal filter material of the other Example which divides | segments a pattern into a concentric ring. Similarly, it is a top view of the division | segmentation thin plate metal filter medium of a fan-shaped part. Similarly, it is a top view of the other Example of a sheet metal filter medium. Similarly, it is a top view of the division | segmentation thin plate metal filter medium of a semi-annular part. Similarly, it is a top view of the other Example of a sheet metal filter medium. Similarly, it is a top view of the division | segmentation thin plate filter medium of a fan-shaped part. Similarly, it is a top view of the other Example of a sheet metal filter medium. It is a conceptual diagram which shows the dehydration effect | action of a continuous pressure dehydrator. It is a conceptual diagram which shows the dehydration effect | action of a screw press.

DESCRIPTION OF SYMBOLS 1 Filter plate 2 Filter chamber outer ring 4 Filter chamber 12 Impeller 14, 27, 28, 30, 32, 36 Thin plate metal filter medium 17 Fine hole 27a, 27b, 27c, 28a, 28b, 28c, 29, 31, 33 Divided thin plate metal Filter media 27d, 28d, 29a, 31a, 34a, 34b, 35a, 35b Non-porous region 34, 35 Split thin plate filter media

Claims (8)

A disk-shaped filter plate (1, 1) having a pair of filtration surfaces, an annular filter chamber outer ring (2), and an inner ring support cylinder (3) form a filtration chamber (4), and an inner ring support cylinder (3 internal fluid chamber of) (7) Toro outdoor ring (2) to the cake discharge port (23) provided, arranged a rotatable impeller (12) to the filtration chamber (4), filtering chamber ( 4) In the pressure dehydrator in which the filtration proceeds from the central part toward the outer peripheral part, according to the decrease in the amount of filtrate to be discharged from the central part toward the outer peripheral part and the increase in the filtration pressure , the filtration plate (1, The fine holes (17) of the thin sheet metal filter media (14, 27, 28, 30, 32, 36) arranged in 1) are arranged in a concentric ring shape, and the hole diameter is gradually reduced from the central part toward the outer peripheral part. A continuous pressure dehydrator using a thin sheet metal filter.   The thin plate metal filter medium (27, 28) is formed into a plurality of concentric annular divided thin plate metal filter media (27a, 27b, 27c, 28a, 28b, 28c), and the divided thin plate metal filter media (27a, 27b, 27c, 28a). 28b, 28c), wherein the fine holes (17) are gradually reduced from the central portion toward the outer peripheral portion, and the continuous pressure dehydrator using the thin plate metal filter medium according to claim 1.   The thin plate metal filter medium (27) is divided into three concentric annular patterns, and the area ratio of each divided thin plate metal filter medium (27a, 27b, 27c) is 2: 1: 1 from the center toward the outer periphery. A continuous pressure dehydrator using the thin metal filter medium according to claim 2.   The thin plate metal filter medium (28) is divided into three concentric annular patterns, and the area ratio of each divided thin plate metal filter medium (28a, 28b, 28c) is 1: 1: 1 from the center toward the outer periphery. A continuous pressure dehydrator using the thin metal filter medium according to claim 2. The sheet metal filter medium (30, 32) is composed of a plurality of parts divided sheet metal filter media (29, 31) divided in the radial direction, and the side edges of the divided sheet metal filter media (29, 31) are non-porous. The continuous pressurization dehydrator using the thin sheet metal filter medium according to any one of claims 1 to 4, wherein a region (29a, 31a) is provided.   The thin plate metal filter medium is constituted by a divided thin plate filter medium (34, 35) of a plurality of parts divided in a concentric ring shape and a radial direction, and a non-porous region (34a, 34b, 35a, 35b) at a joint portion of the divided thin plate filter medium. A continuous pressure dehydrator using the thin sheet metal filter medium according to claim 5.   The fine hole (17) of the thin plate metal filter medium (14, 27, 28, 30, 32, 36) is formed in a conical shape in the through-direction cross section, and expands from the filtration chamber side toward the filtrate discharge side. (17) The continuous pressure dehydrator using the thin sheet metal filter medium according to any one of claims 1 to 6,   The continuous pressure dehydrator using the thin metal filter medium according to any one of claims 1 to 7, wherein the fine holes (17) are processed by photoetching.