JP7326032B2 - filtration device - Google Patents

Description

For example, the present invention can be applied to organic sludge produced by adding a flocculant to sewage sludge generated from a sewage treatment plant and flocculating it, wastewater sludge from chemical factories and food factories, pulp slurry, and other objects to be treated with warm water. The present invention relates to a filtering device that performs a process of supplying and concentrating a washing liquid.

As such a filtration device, for example, in Patent Document 1, a filter cylinder (filter screen) is accommodated in an outer cylinder, a spiral screw (screw blades) is rotatably accommodated inside the filter cylinder, and the spiral screw is rotated. By driving, the sludge introduced into the filter cylinder from the sludge flocculation tank is transported, and the water contained in the sludge passes through the filtration surface of the filter cylinder and is discharged as a separated liquid from the separated liquid discharge pipe to remove the sludge. In a sludge thickener that thickens and discharges the thickened sludge from the inside of the filter cylinder, the rotating shaft of the spiral screw is hollow, and washing water (washing liquid) flows from the rotating shaft into the filter cylinder to remove the sludge in the filter cylinder. It has been proposed to wash the

In such a filtration device, the coagulated sludge introduced into the filter cylinder is conveyed downward by the rotating spiral screw, and the water contained therein passes through the filtration surface of the filter cylinder and into the outer cylinder. It is contained as a separate liquid (filtrate). Water is separated from the flocculated sludge that is conveyed downward in the filter cylinder to become thickened sludge. As a result of washing the sludge flocs in the process of passing through the gaps of the highly concentrated sludge flocs remaining in the lower part of the filter cylinder by flowing out and being supplied, the M alkali contained in the thickened sludge is effectively removed by the washing water. It is washed away and the M alkalinity of the thickened sludge is lowered.

JP 2008-043914 A

By the way, in such a filtering device, if the cleaning liquid is simply supplied to the organic sludge in the filter screen, depending on the flow velocity and flow rate of the cleaning liquid, the cleaning liquid may flow without sufficiently contacting the organic sludge. It may not be possible to obtain a good cleaning effect. In particular, when hot water having a temperature higher than that of the organic sludge is supplied as the cleaning liquid, if the cleaning liquid is discharged outside the filter screen without sufficiently contacting the organic sludge in the filter screen, the hot water becomes organic. Only the filtrate separated from the sludge is heated, and it becomes difficult to lower the water content of the organic sludge.

The present invention has been made under such a background, and when a cleaning liquid is supplied to an object to be treated such as organic sludge in a filter screen, the cleaning liquid is discharged without sufficiently contacting the object to be treated. To provide a filtration device capable of effectively heating an object to be treated, even when hot water is supplied as a washing liquid.

In order to solve the above problems and achieve such objects, the present invention provides a cylindrical filter screen centered on an axis, a filtrate chamber disposed on the outer periphery of the filter screen, and the axis. and a conveying means housed in the filtering screen having a rotating shaft extending along the rotating shaft, screw blades spirally arranged around the rotating shaft, and a nozzle for discharging the washing liquid into the filtering screen. and discharging cleaning liquid from the nozzle and supplying it to the object to be treated while conveying the object to be treated supplied into the filter screen in the axial direction by the conveying means, the filtering device comprising: The filtering screen is characterized by partially including a shielding portion that shields the inside and outside of the filtering screen in the axial direction.

In the filtering device constructed in this manner, the cylindrical filtering screen centered on the axis has a shielding portion that shields the inside and outside of the filtering screen partially in the axial direction, so that the air is discharged from the nozzle. By arranging the filter screen so that the cleaning liquid diffused in the radial direction with respect to the axis reaches this shielding portion at the position of the filter screen, the cleaning liquid is prevented from immediately flowing out into the filtrate chamber on the outer circumference of the filter screen. It can be made to stay inside and wash the object to be processed.

When the material to be processed supplied into the filter screen is transported in the axial direction by the transport means, the material to be processed having a high moisture content is filtered on the supply side of the material to be processed into the filter screen. A filter screen is required for concentration, and a filter screen is also required for re-concentrating the material to be processed diluted by the washing liquid on the transport direction side of the material to be processed. For this reason, it is desirable that the filtering screens remain on one end side and the other end side of the shielding portion in the axial direction. Further, by arranging a plurality of nozzles in a helical shape in accordance with the spiral formed by the screw blades, the distance between the screw blades and the nozzles is kept constant, and the cleaning liquid is uniformly applied to the object to be processed conveyed by the screw blades. can be supplied.

Moreover, the filter screen may have the axis extending in the horizontal direction. More effectively, it is a cylindrical filter screen centered on said axis extending in the direction. In this way, when the axis of the filter screen extends in the vertical direction and the washing liquid is hot water with a higher temperature than the object to be treated, for example when the object to be treated is organic sludge, the organic sludge is heated by the hot water. As a result, the water retained in the organic sludge is separated by the heat denaturation of the protein and the viscosity of the organic sludge is reduced, so that the organic sludge can be concentrated with a smaller filtration area. Hot water rises in the organic sludge in the filter screen due to the difference in specific gravity from the organic sludge. Therefore, when the axis of the filter screen extends in the vertical direction and the cleaning liquid is warm water having a higher temperature than the object to be treated, the upper end of the shielding portion is located above the nozzle in the axial direction. preferably on the side.

Furthermore, when the axis of the filter screen extends in the vertical direction and the cleaning liquid is warm water having a higher temperature than the object to be treated, the nozzle is opened downward to discharge the cleaning liquid from the nozzle. Since the washing liquid descends once through the material to be treated in the filter screen and then rises due to the difference in specific gravity, it can be efficiently mixed with the material to be treated and heated.

Furthermore, when the axis of the filter screen extends in the vertical direction, the cleaning liquid quickly reaches the position of the filter screen when the flow velocity or flow rate of the cleaning liquid discharged from the nozzle into the filter screen is high. Therefore, if the nozzle is open below the lower end of the shielding portion in the axial direction, the washing liquid may immediately escape from below the shielding portion into the filtrate chamber. Therefore, when the flow velocity and flow rate of the cleaning liquid are high, it is desirable that the nozzle be open between the upper end and the lower end of the shielding portion in the axial direction.

On the other hand, when the axis of the filter screen extends in the vertical direction, conversely, when the flow velocity or flow rate of the cleaning liquid discharged from the nozzle into the filter screen is low, the temperature of the cleaning liquid is higher than that of the object to be processed. When the water is hot, the washing liquid slowly rises through the object and reaches the filter screen. The washing liquid passes over the shield and escapes from above the shield into the filtrate chamber. Therefore, when the flow velocity and flow rate of the cleaning liquid are low in this way, it is desirable that the nozzle is opened below the lower end of the shielding portion in the axial direction.

As described above, according to the present invention, the cleaning liquid can be retained in the filter screen, the cleaning liquid can sufficiently contact the object to be treated, and the object to be treated can be efficiently washed. becomes. In particular, when the cleaning liquid is hot water with a higher temperature than the object to be treated, it becomes possible to effectively heat the object to be treated, and dehydration to a lower moisture content in the subsequent dehydrator is possible. can.

BRIEF DESCRIPTION OF THE DRAWINGS It is a longitudinal cross-sectional view which shows 1st Embodiment of the filtration apparatus of this invention (However, the coagulation tank is drawn small for description.). In the embodiment shown in FIG. 1, when the nozzle is open between the upper and lower ends of the shield in the axial direction, the flow velocity of the cleaning liquid is low (left side of FIG. 2) and high (right side of FIG. 2). 1 is a schematic diagram for explaining the flow of a cleaning liquid. FIG. In the embodiment shown in FIG. 1, when the nozzle opens below the lower end of the shielding part in the axial direction, when the flow velocity of the cleaning liquid is low (left side in FIG. 3) and when it is high (right side in FIG. 3) It is a schematic diagram explaining the flow of cleaning liquid. FIG. 3 is a side view showing a first modification of the conveying means of the embodiment shown in FIG. 1; FIG. 5 is a cross-sectional view taken along line AA in FIG. 4; It is the side view which looked at the 1st modification shown in FIG. 4 from the direction rotated 90 degrees around the axis. It is the perspective view which looked at the 1st modification shown in FIG. 4 from the lower side. FIG. 8 is an enlarged view of a B portion in FIG. 7; FIG. 5 is a side view showing a second modification of the conveying means of the embodiment shown in FIG. 1; FIG. 10 is a cross-sectional view taken along line AA in FIG. 9; FIG. 10 is a side view of the second modification shown in FIG. 9 viewed from a direction rotated 90° around the axis; FIG. 10 is a perspective view of the second modification shown in FIG. 9 as seen from below; 13 is an enlarged view of a B portion in FIG. 12; FIG. FIG. 11 is a side view showing a third modification of the conveying means of the embodiment shown in FIG. 1; FIG. 15 is a cross-sectional view taken along line AA in FIG. 14; 14. It is BB sectional drawing in FIG. 17 is a cross-sectional view along CC in FIG. 16; FIG. FIG. 17 is a cross-sectional view along DD in FIG. 16; 16 is an EE cross-sectional view in FIG. 15; FIG. FIG. 15 is a side view of the third modification shown in FIG. 14 as viewed from a direction rotated by 90° around the axis; It is the perspective view which looked at the 3rd modification shown in FIG. 14 from the lower side. It is a longitudinal cross-sectional view showing a second embodiment of the filtration device of the present invention (however, for the sake of explanation, the coagulation tank is drawn small).

1 to 3 show a first embodiment of the filtering device of the present invention. The filtration device 1 of the present embodiment solidifies by adding a macromolecular flocculant (polymer) B to organic sludge A such as mixed raw sludge generated and supplied from a sewage treatment plant and stirring in a flocculation tank 2. This is a vertical concentrating apparatus for organic sludge that condenses flocculated sludge C, which has been flocculated to some extent, as a material to be treated.

This filtration device 1 is provided with a bottomed cylindrical thickening tank 3 centered on an axis O extending in the longitudinal direction, in which the flocculated sludge C supplied from the flocculation tank 2 is held, and the flocculated sludge C is thickened. It is supplied into the concentration tank 3 from the upper part of the tank 3 . However, the cylindrical body of the thickening tank 3 is a filter screen 3a formed of wedge wire, punching metal, etc., except for the shielding part described later, and a jacket-like outer periphery of the filter screen 3a. A filtrate chamber 4 is provided.

Inside the filter screen 3a of the thickening tank 3, a hollow cylindrical rotating shaft 5a that rotates about the axis O extending along the axis O of the thickening tank 3, and the rotating shaft 5a Conveying means 5 with screw blades 5b arranged helically around it are accommodated. Further, a rotation drive means 5c such as a motor for rotating the rotation shaft 5a is arranged in the upper part of the thickening tank 3 and connected to the rotation shaft 5a.

The rotating shaft 5a and the screw blades 5b of the conveying means 5 are rotated around the axis O by the rotary drive means 5c, so that the flocculated sludge C supplied from the upper part of the thickening tank 3 is conveyed downward to the filtration screen 3a. , the sludge is concentrated to a sludge concentration of 5 wt % or more, preferably in the range of 8 wt % to 10 wt %.

The bottom portion of the concentration tank 3 and the bottom portion of the flocculation tank 2 are formed in a truncated cone shape whose diameter decreases downward. Water separated from the flocculated sludge C by the filter screen 3a of the thickening tank 3 is stored in a jacket-like filtrate chamber 4 on the outer periphery of the thickening tank 3 and treated as waste water E.

Furthermore, in this embodiment, the washing liquid F is supplied by the pump P from the lower end of the rotating shaft 5a into the hollow rotating shaft 5a of the conveying means 5, and is discharged from the nozzle 6 provided on the rotating shaft 5a to the filtering screen 3a. It is mixed with the coagulated sludge C (organic sludge) inside. In this embodiment, the cleaning liquid F is warm water having a temperature higher than the temperature of the flocculated sludge C, in the range of 50°C or higher and lower than 100°C, preferably in the range of 60°C or higher and 90°C or lower.

A plurality of (four) through-holes (not shown) are formed in the rotating shaft 5a at equal intervals in the circumferential direction at positions closer to the lower end than the central portion in the direction of the axis O. As shown in FIG. In this embodiment, these through holes are formed at the same positions in the axis O direction. Here, the nozzle 6 in this embodiment is an L-shaped elbow pipe of the same shape and size that is joined to the rotary shaft 5a so that the inside communicates with these through holes. The opening on the side opposite to the joint with the is open downward.

The filtering screen 3a is partially provided with a shielding portion 3b for shielding the inside and outside of the filtering screen 3a in the direction of the axis O. As shown in FIG. The shielding portion 3b may be formed by cutting the filter screen 3a so as to divide the filter screen 3a in the direction of the axis O, and connecting the parts between them with a cylindrical plate. It may be covered with a plate.

Further, in the present embodiment in which the cleaning liquid F is hot water as described above, the upper end of the shielding portion 3b is located on the upper end side in the direction of the axis O from the opening of the nozzle 6. As shown in FIG. In the present embodiment, the upper and lower edges of the shielding portion 3b are positioned on planes perpendicular to the axis O and spaced apart from the upper and lower ends of the filtration screen 3a. Filtration screens 3a formed of wedge wires, punching metals, etc. as described above are left on the upper end (one end) side and the lower end (other end) side of the shielding portion 3b in the direction of the axis O. Further, in the thickening tank 3, the shielding portion 3b shields the inside and outside of the filter screen 3a only at one location in the direction of the axis O in this embodiment.

In the filtration device 1 configured as described above, the flocculated sludge C supplied to the thickening tank 3 is conveyed downward by the conveying means 5 as described above, while the upper end side of the thickening tank 3 is higher than the shielding portion 3b. Aggregated sludge C having a high water content is concentrated by separating water from the filter screen 3a on the upper end side. Furthermore, by discharging and supplying the cleaning liquid F from the nozzle 6, the flocculated sludge C staying at the bottom of the thickening tank 3 is washed and the M alkalinity is lowered. The filter screen 3a also concentrates on the lower end side of the shielding portion 3b of 3.

In particular, in the present embodiment, since the cleaning liquid F is hot water having a temperature higher than the temperature of the flocculated sludge C, the hot water reduces the viscosity of the flocculated sludge C, and the hot water heats the flocculated sludge C. The proteins in the sludge are thermally denatured, and the retained water is separated and discharged as the wastewater E, so that the thickened sludge D can be effectively concentrated to the concentration described above.

In the filter device 1 for organic sludge having the above configuration, the cylindrical filter screen 3a centered on the axis O extending in the vertical direction has a sealed shielding portion 3b that shields the inside and outside of the filter screen 3a. Since the washing liquid F discharged from the nozzle 6 and diffused in the radial direction with respect to the axis O is retained in the thickening tank 3 by the blocking portion 3b, the flocculated sludge C can be washed efficiently. can be done. Therefore, it is possible to prevent the washing liquid F from reaching the filtration screen 3a without sufficiently contacting the flocculated sludge C and being discharged into the filtrate chamber 4 as it is.

In particular, as described above, the cleaning liquid F in the present embodiment is warm water having a higher temperature than the flocculated sludge C, and such hot water rises in the flocculated sludge C in the filter screen 3a due to the difference in specific gravity from the flocculated sludge C. Resulting in. On the other hand, in the present embodiment, since the upper end of the shielding portion 3b is located on the upper end side in the direction of the axis O than the nozzle 6, the cleaning liquid (hot water) F rising in the aggregated sludge C is reliably removed. It is possible to prevent the coagulated sludge C from being discharged into the filtrate chamber 4 by shielding the sludge, and to concentrate the flocculated sludge C by more efficient heating.

While the washing liquid F is warm water having a temperature higher than that of the aggregated sludge C rising in the aggregated sludge C, in the present embodiment, the nozzle 6 for supplying the washing liquid F into the aggregated sludge C is opened downward. are doing. Therefore, the washing liquid F is discharged from the nozzle 6, descends once in the flocculated sludge C, and then rises, staying in the flocculated sludge C for a long time. Warming can be used to reduce the concentration.

By the way, in the filtering device 1 of the present embodiment, the upper end of the blocking portion 3b of the filter screen 3a is located on the upper end side in the direction of the axis O from the opening of the nozzle 6 as described above, and the lower end is located on the upper end side of FIG. 2, the opening of the nozzle 6 is located on the lower end side of the center of the axis O, and the opening of the nozzle 6 opens downward between the upper end and the lower end of the shielding portion 3b in the direction of the axis O. there is

However, in such a case, if the flow velocity and flow rate of the cleaning liquid F, which is hot water, is low, the distance that the cleaning liquid F once descends in the coagulated sludge C is short, as shown on the left side of FIG. There is a risk that it will reach the filter screen 3a above the upper end of the filter 3b and be discharged into the filtrate chamber 4 as it is.

Therefore, in the case where the opening of the nozzle 6 is opened downward between the upper end and the lower end of the shielding portion 3b in the direction of the axis O, the flow speed and flow rate of the cleaning liquid F, which is warm water, is increased to increase the flow rate of the cleaning liquid F. By lengthening the distance that the washing liquid F once descends in the flocculated sludge C, as shown on the right side of FIG. It can be adjusted to the position of 3b.

Therefore, it is possible to prevent the washing liquid F from reaching the filtration screen 3a and being discharged to the filtrate chamber 4 as it is, and the washing liquid F is retained in the flocculated sludge C for a long period of time. In this case, the flocculated sludge C can be effectively heated. In other words, when the cleaning liquid F is warm water and the flow rate is high, it is desirable that the nozzle 6 be open between the upper end and the lower end of the shielding portion 3b in the direction of the axis O. As shown in FIG.

On the other hand, even when the cleaning liquid F is hot water having a higher temperature than the flocculated sludge C (organic sludge) and the upper end of the shielding portion 3b is positioned higher than the nozzle 6 in the direction of the axis O, the 3, when the nozzle 6 is opened downward in the direction of the axis O from the lower end of the shielding portion 3b, if the flow velocity and flow rate of the cleaning liquid F is high, the downward movement will occur as shown on the right side of FIG. There is a risk that the washing liquid F, which has turned upward, will reach the filter screen 3a and be discharged into the filtrate chamber 4 before reaching the blocking portion 3b.

Therefore, when the nozzle 6 is opened below the lower end of the shielding portion 3b in the direction of the axis O, the velocity and flow rate of the cleaning liquid F are lowered so that the nozzle 6 descends as shown on the left side of FIG. The position at which the washing liquid F, which has turned upward, reaches the filter screen 3a in the radial direction with respect to the axis O can be aligned with the position of the shielding portion 3b.

Therefore, the cleaning liquid F can be retained in the flocculated sludge C for a long time, and the flocculated sludge C can be effectively heated when the cleaning liquid F is hot water. In other words, when the flow velocity or flow rate of the cleaning liquid F is low, it is desirable that the nozzle 6 opens below the lower end of the shielding portion 3b in the direction of the axis O. As shown in FIG. In this embodiment, the cleaning liquid F is supplied through the inside of the hollow cylindrical rotating shaft 5a, but the cleaning liquid F may be supplied through a pipe inserted in the direction of the axis O of the rotating shaft 5a.

Next, FIGS. 4 to 8 show a first modification of the conveying means 5 in the filtration device 1 of the embodiment shown in FIGS. The same reference numerals are assigned to portions common to the embodiment shown in FIG. 1, including modifications. In the conveying means 5 of the embodiment shown in FIGS. 1 to 3, the plurality of through-holes of the rotary shaft 5a and the nozzles 6 are arranged at the same position in the direction of the axis O. In the conveying means 5 of the modified example, the plurality of through holes of the rotating shaft 5a and the nozzles 6 are evenly spaced in the circumferential direction, but are shifted in the direction of the axis O to match the spiral formed by the screw blades 5b. are arranged in a pattern.

The position of the through-hole of the rotary shaft 5a in the direction of the axis O is located substantially in the center of the screw blade 5b adjacent to the upper end side and the lower end side of the through-hole in the direction of the axis O. As shown in FIG. L-shaped elbow pipe-like nozzles 6 of the same shape and size are joined to the rotating shaft 5a so that the insides communicate with these through holes and open downward. Therefore, if the torsion of the screw blades 5b is constant, the amount of deviation in the direction of the axis O of the nozzles 6 adjacent in the circumferential direction is constant.

In the filtration device having the conveying means 5 of the first modified example configured in this way, the plurality of nozzles 6 are spirally arranged in accordance with the spiral formed by the screw blades 5b. The interval between the vane 5b and the nozzle 6 can be made constant. Therefore, according to the filtration device having the conveying means 5 of the first modification, it is possible to uniformly supply the cleaning liquid F to the flocculated sludge C (organic sludge) conveyed by the screw blades 5b. processing such as concentration can be achieved.

9 to 13 show a second modification of the conveying means 5 in the filtering device 1 of the embodiment shown in FIGS. 1 to 3. FIG. In the conveying means 5 of the embodiment shown in FIGS. 1 to 3 and the first modified example shown in FIGS. While the nozzle 6 is joined and opens downward, in the conveying means 5 of this second modification, it is displaced in the direction of the axis O in accordance with the spiral formed by the screw blades 5b as in the first modification. A substantially hemispherical hollow cap-shaped nozzle 6 is joined to the rotating shaft 5a so that the inside communicates with the through holes arranged in a spiral shape, and an opening 6a is formed in the nozzle 6 so as to open downward. is formed.

In the conveying means 5 of the second modified example, as in the first modified example, the plurality of nozzles 6 are spirally arranged in accordance with the spiral formed by the screw blades 5b. The cleaning liquid F can be uniformly supplied to the flocculated sludge C (organic sludge) conveyed by the 5b, and the L like the conveying means 5 of the embodiment shown in FIGS. The portion of the hemispherical nozzle 6 protruding from the rotating shaft 5a can be made smaller than that of the letter-shaped elbow tubular nozzle 6 .

Therefore, when the conveying means 5 is rotated by the rotation driving means 5c, the resistance received by the nozzle 6 from the flocculated sludge C (organic sludge) can be reduced, and partial excessive concentration in the thickening tank 3 can be prevented. In addition, it is possible to prevent clogging of sludge in the thickening tank 3 . In addition, since the resistance to which the nozzle 6 is subjected is reduced in this way, the risk of damage such as bending as in the L-shaped elbow tube-like nozzle 6 is reduced.

Further, FIGS. 14 to 21 show a third modification of the conveying means 5 in the filtering device 1 of the embodiment shown in FIGS. 1 to 3. FIG. In the embodiment and the first and second modifications shown in FIGS. In this modification, the screw blade 5b of the conveying means 5 is provided with a supply passage 7 communicating with the inside of the hollow rotating shaft 5a, and the supply passage 7 is provided with a nozzle 8 opening downward.

Here, in this third modified example, a cross section "C" flattened in the direction of the axis O extending radially with respect to the axis O is provided on the lower surface of the screw blade 5b closer to the lower end than the central portion in the direction of the axis O of the rotating shaft 5a. A linear radial supply passage 7a having a letter shape is joined with the opening facing upward. As shown in FIG. 17, the radially inner peripheral portion of the radial supply passage 7a with respect to the axis O is joined to the hollow rotary shaft 5a and communicates with the inside of the rotary shaft 5a, while the outer peripheral portion is closed. ing.

Similarly, on the lower surface of the screw blade 5b, a space is provided between the inner peripheral side and the outer peripheral side in the radial direction with respect to the axis O, and an arc shape with a cross section flattened in the direction of the axis O and centered on the axis O is provided. A plurality (two in this embodiment) of the circumferential supply passages 7b are concentrically joined along the lower surface of the screw blade 5b so as to make approximately one turn downward with the opening facing upward. The upper ends of these circumferential supply channels 7b are joined to communicate with the radial supply channel 7a, and the lower ends thereof are closed.

A plurality (two) of nozzles 8 are provided on the lower surfaces of the inner peripheral portion and the outer peripheral portion of the radial supply passage 7a joined to the plurality (two) of the circumferential supply passages 7b so as to open downward. ing. Furthermore, on the lower surface of the circumferential supply path 7b, a plurality of nozzles 8 are opened downward from the plurality (two) of the nozzles 8 of the radial supply path 7a at intervals in the circumferential direction. is provided. In this embodiment, the nozzles 8 of the plurality (two) of the circumferential supply passages 7b are arranged at regular intervals of 45° around the axis O from the plurality (two) of the nozzles 8 of the radial supply passage 7a. It is

In the third modified example configured as described above, the cleaning liquid F supplied through the inside of the hollow rotary shaft 5a flows through the radial direction supply channel 7a of the supply channels 7 communicating with the inside of the rotary shaft 5a. and discharged downward from a plurality of (two) nozzles 8 . Further, the cleaning liquid F that has flowed into the radial supply passage 7a flows into a plurality (two) of circumferential supply passages 7b that communicate with the radial supply passage 7a, and is also discharged downward from each nozzle 8 to form flocculated sludge. It is supplied to C (object to be processed).

In the filtration device 1 provided with the conveying means 5 of the third modified example, the nozzle 8 for supplying the cleaning liquid F to the flocculated sludge C (object to be treated) is provided on the lower surface of the screw blade 5b of the conveying means 5. Since it is arranged in the radial supply path 7a and the circumferential supply path 7b of the supply path 7, the distance between the screw blade 5b and the nozzle 8 is naturally constant, and the flocculated sludge is collected as in the first and second modifications. It is possible to uniformly supply the cleaning liquid F to C and to perform processing such as efficient concentration.

In addition, since the circumferential supply path 7b of the supply path 7 has a U-shaped cross section flattened in the direction of the axis O and has an arc shape centered on the axis O, it receives from the aggregated sludge C as the conveying means 5 rotates. With less resistance, it is possible to suppress partial excessive concentration in the thickening tank 3 and prevent sludge clogging in the thickening tank 3 . In this third modification, instead of supplying the cleaning liquid F from all of the nozzles 8, the nozzles 8 that supply the cleaning liquid F are selected by attaching plugs to the nozzles 8, and the unselected nozzles 8 are closed. You may make it stop.

Furthermore, FIG. 22 shows a second embodiment of the filtering device of the present invention, and the same reference numerals are assigned to the parts common to the first embodiment shown in FIG. While the filter screen 3a of the first embodiment has a cylindrical shape with an axis O extending in the longitudinal direction, in the filter device 1 of the second embodiment, the axis O of the filter screen 3a extends in the lateral direction. It is characterized by

In this embodiment, the flocculated sludge C (object to be treated) is supplied from the top of one end (the left end in FIG. 22) of the thickening tank 3 into the filtration screen 3a and conveyed by the conveying means 5 to the other end (the right end in FIG. 22). It is filtered and concentrated while being conveyed to the thickening tank 3, and is discharged from the bottom of the thickening tank 3 at the other end side as thickened sludge D. Washing water F is hot water having a temperature higher than that of coagulated sludge C, as in the first embodiment, and is supplied from the other end of the thickening tank 3 into the hollow rotating shaft 5a, and is supplied from the nozzle 6 to the other end of the thickening tank 3. discharged towards.

In FIG. 22, the nozzle 6 is positioned between one end and the other end of the shielding portion 3b in the direction of the axis O and opens toward the other end. When opening toward the other end side of the filter screen 3a, depending on the flow rate and flow velocity of the washing water F, the opening may be made closer to the one end side than the one end of the shielding portion 3b. Further, in FIG. 22, the nozzles 6 are arranged at the same position in the direction of the axis O, but like the conveying means 5 and the like of the first modification of the first embodiment, the plurality of nozzles 6 are It may be spirally arranged in accordance with the spiral formed by the screw blades 5b.

Furthermore, in the present embodiment, the nozzle 6 does not have to open toward the other end side, and may open toward the outer peripheral side with respect to the axis O, for example. In this case, as shown in FIG. 22, the opening of the nozzle 6 is positioned between one end and the other end of the shielding portion 3b in the direction of the axis O and opens toward the other end. is desirable.

Furthermore, the nozzle 6 may open toward one end side of the filter screen 3a in the direction of the axis O, contrary to what is shown in FIG. In this case, depending on the flow rate and flow velocity of the cleaning water F, the opening of the nozzle 6 may be positioned closer to the other end than the other end of the shielding portion 3b in the direction of the axis O.

In the filtering device 1 of the second embodiment as described above, the washing liquid F is retained in the filter screen 3a by the shielding part 3b, so that the washing liquid F is brought into sufficient contact with the flocculated sludge C (object to be treated). Therefore, the flocculated sludge C can be washed efficiently. In particular, when the cleaning liquid F is hot water having a higher temperature than the flocculated sludge C, the flocculated sludge C can be effectively heated, so that it can be dehydrated to a lower moisture content in the subsequent dehydrator. can.

Although embodiments of the invention have been described above, such embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as in the scope of the invention described in the claims and equivalents thereof.

Next, the effects of the present invention will be demonstrated by giving examples of the present invention. In ^this example, using the filtration device 1 based on the embodiment shown in FIG. ℃ of hot water was supplied at a flow rate of 1.3 m ³ /h and concentrated, and concentrated sludge D with a sludge concentration of 8 wt% was extracted at a flow rate of 1.3 m ³ /h.

In this example, the area of the shielding portion 3b of the thickening tank 3 was about 1/3 of the area of the entire circumferential surface of the thickening tank 3 and about 1/2 of the filtering screen 3a. In addition, as a comparative example for this example, a concentration treatment was performed under the same conditions as in the example using a filtration device in which the entire circumferential surface of the concentration tank 3 was the filtration screen 3a without providing the shielding part 3b. Then, in these examples and comparative examples, the temperature of the thickened sludge D and the temperature of the waste water E discharged to the filtrate chamber 4 are measured, and the heat quantity of the thickened sludge D and the heat quantity of the hot water (washing liquid F) are calculated. Warming efficiency, which is the ratio between theoretical sludge temperature and actual sludge temperature, was calculated.

As a result, in the comparative example, the temperature of the thickened sludge D was 34 ° C., whereas the temperature of the waste water E was 39 ° C. As a result, the waste water E was warmed more than the thickened sludge D by hot water. , the heating efficiency was also low at 63%. On the other hand, in the example, the temperature of the waste water E was 37° C., whereas the temperature of the thickened sludge D was 48° C., and the thick sludge D was warmed by 10° C. or more than the waste water E. The heating efficiency was 91%, close to 100%.

REFERENCE SIGNS LIST 1 filtering device 2 flocculating tank 3 thickening tank 3a filtering screen 3b shielding part 4 filtrate chamber 5 conveying means 5a rotating shaft 5b screw blade 5c rotary driving means 6, 8 nozzle 7 supply path 7a radial supply path 7b circumferential supply path O filtration Axis of screen 3a A Organic sludge B Polymer flocculant C Aggregated sludge D Thickened sludge E Waste water F Cleaning liquid (hot water)

Claims (8)

A cylindrical thickening tank centered on the axis,
a filtration screen , which is a portion of the thickening tank excluding the shielding portion ;
a filtrate chamber disposed on the outer periphery of the filter screen;
Conveying means housed in the filter screen, comprising a rotating shaft extending along the axis and screw blades spirally arranged around the rotating shaft;
and a nozzle for discharging the cleaning liquid in the filtering screen,
A filtering device that discharges a cleaning liquid from the nozzle and supplies the cleaning liquid to the object to be treated while conveying the object to be treated that has been supplied into the filtration screen in the axial direction by the conveying means,
The location where the shielding portion shields the inside and outside of the filter screen in the thickening tank is one location in the axial direction,
The filtering device , wherein the area of the shielding portion is about 1/3 of the area of the entire circumferential surface of the thickening tank and about 1/2 of the area of the filtering screen. 2. The filtering device according to claim 1, wherein the filtering screen is left on one end side and the other end side of the shielding portion in the axial direction. 3. The filtering device according to claim 1, wherein the plurality of nozzles are spirally arranged in accordance with the spiral formed by the screw blades. 4. A filtration apparatus according to any one of claims 1 to 3, wherein the filtration screen is a cylindrical filtration screen centered on the longitudinally extending axis. 5. The filtering device according to claim 4, wherein the cleaning liquid is hot water having a temperature higher than that of the object to be processed, and the upper end of the shielding portion is located on the upper end side of the nozzle in the axial direction. . 6. The filtering device according to claim 4, wherein the cleaning liquid is warm water having a temperature higher than that of the object to be processed, and the nozzle is opened downward. 7. The filtering device according to any one of claims 4 to 6, wherein the nozzle opens between the upper end and the lower end of the shielding portion in the axial direction. 7. The filtering device according to any one of claims 4 to 6, wherein the nozzle opens below a lower end of the shielding portion in the axial direction.

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