JP7535345B2 - Impurity removal screen device - Google Patents

Description

The present invention relates to an impurity removal screen device that has a gap connecting the upstream and downstream sides of received wastewater and transports impurities that are captured and cannot pass through the gap upward.

In a sewage treatment system, wastewater consisting of sewage generally flows through the grit basin, primary sedimentation basin, reaction tank, and final sedimentation basin in the listed order and is purified. For example, in the primary sedimentation basin, wastewater containing sludge that has settled at the bottom of the basin (raw sludge) is transported to the outside of the primary sedimentation basin by a sludge pump or the like, thickened, dehydrated, and then incinerated. Since the raw sludge contains impurities such as screen residue, the impurities are generally removed from the raw sludge by a raw sludge impurity removal screen device before being thickened and dehydrated. In addition, wastewater containing scum, which is an impurity floating near the water surface of the primary sedimentation basin (scum water), is collected in a scum pit and then transported from the scum pit to the outside of the primary sedimentation basin by a scum pump. The scum water transported to the outside of the primary sedimentation basin has the scum removed by a scum impurity removal screen device, and is then returned to the sewage treatment plant. These impurity removal screen devices are placed in a tank that receives raw sludge and scum water from the primary settling tank (see, for example, Patent Documents 1 and 2).

The impurity removal screen device described in Patent Document 1 and Patent Document 2 includes a plurality of fixed screen members and a movable screen member disposed between the plurality of fixed screen members. The fixed screen members each extend diagonally upward, with their uppermost portions protruding from the water surface of the tank or the like. The fixed screen members are also stepped with a plurality of fixed steps arranged in the direction of extension. The movable screen members also extend diagonally upward, with a plurality of movable steps arranged in the direction of extension. The movable screen members repeatedly move upward and downward relative to the fixed screen members to transport impurities toward the top of the fixed screen members. The impurities transported to the top of the fixed screen members fall toward a chute provided downstream of the fixed screen members and are discharged to the outside of the impurity removal screen device. In the impurity removal screen device described in Patent Documents 1 and 2, even if impurities that cannot pass through the gap between the fixed screen member and the movable screen member fill the gap and cause a clog, all of the trapped impurities begin to be transferred as soon as the movable screen member is moved, so the clog can be quickly cleared. Therefore, even if a large amount of sewage or a large amount of impurities flows into the tank, the water level in the tank can be immediately prevented from rising by moving the movable screen member, and the sewage can be prevented from overflowing outside the tank.

JP 2014-114574 A JP 2015-017462 A

However, the impurity removal screen devices described in Patent Documents 1 and 2 have the problem that they consume a large amount of electricity because they repeatedly move the heavy movable screen members upward and downward.

In view of the above circumstances, the present invention aims to provide an impurity removal screen device that consumes less power.

The impurity removal screen device of the present invention that solves the above-mentioned object includes a plurality of first fixed screen members that are spaced apart from each other in the width direction and have step-like first fixed step portions;
a plurality of first movable screen members each having a stepped first movable step portion that is arranged alternately with the plurality of first fixed screen members in the width direction and repeatedly moves upward and downward to transfer the impurities to the upper first fixed step portion, thereby transporting the impurities upward ;
a plurality of second fixed screen members provided at intervals from each other in the width direction and having stepped second fixed step portions;
a plurality of second movable screen members each having a stepped second movable step portion that is arranged alternately with the plurality of second fixed screen members in the width direction and repeatedly moves upward and downward to transfer the impurities to the upper second fixed step portion, thereby transporting the impurities upward ;
a first screen group consisting of a plurality of the first fixed screen members and a plurality of the first movable screen members, and a second screen group consisting of a plurality of the second fixed screen members and a plurality of the second movable screen members are arranged to be spaced apart in the width direction,
a drive device for moving the first movable screen members and the second movable screen members upward;
The driving device is characterized by having a common actuator that moves the first movable screen members and the second movable screen members upward with a time lag.

In this impurity removal screen device, the number of the first movable screen members may be the same as the number of the second movable screen members.

The present invention provides an impurity removal screen device that consumes less power.

FIG. 1 is a diagram showing a schematic diagram of some of the facilities in a sewage treatment plant. FIG. 2 is a front view of a raw sludge screening unit provided with the raw sludge impurity removal screening device of this embodiment. FIG. 3 is a cross-sectional view of the raw sludge screen unit shown in FIG. 2 along the line AA. FIG. 2 is a front view of the raw sludge impurity removal screen device. 11A to 11C are diagrams showing the steps of the operation of the first moving screen member and the second moving screen member.

The following describes an embodiment of the present invention with reference to the drawings.

Figure 1 is a schematic diagram showing some of the facilities in a sewage treatment plant.

This figure 1 shows a settling tank 1, a raw sludge screen unit 2, a scum pit 3, and a scum screen unit 4.

The sedimentation tank 1 shown in FIG. 1 receives wastewater (sewage) from one end (left side in FIG. 1) in the longitudinal direction, settles the sludge contained in the received wastewater to the bottom of the tank, and drains it from the other end (right side in FIG. 1). Hereinafter, the left side in FIG. 1 is referred to as the upstream side, and the right side in FIG. 1 is referred to as the downstream side. A sludge pit 11 is provided at the bottom of the upstream side of this sedimentation tank 1, and a drainage gutter 12 is installed near the water surface on the downstream side. In the sedimentation tank 1, the sludge that has settled at the bottom of the tank is collected in the sludge pit 11 by a sludge collector (not shown). The sludge collected in the sludge pit 11 is sent by a sludge pump 13 to a raw sludge screen unit 2 installed outside the sedimentation tank 1. The sludge collected in the sludge pit 11 contains impurities such as screen residue. Hereinafter, the wastewater containing sludge sent from the sludge pit 11 to the raw sludge screen unit 2 is referred to as raw sludge. The raw sludge screening unit 2 is provided with a raw sludge impurity removal screening device 6. As will be described in detail later, impurities contained in the raw sludge are removed by this raw sludge impurity removal screening device 6. The raw sludge from which impurities have been removed by the raw sludge impurity removal screening device 6 is then sent to a sludge concentration treatment facility or a sludge dewatering treatment facility. In the settling tank 1, scum floating near the water surface is scraped up to a drainage gutter 12 by a scum scraper (not shown). The drainage gutter 12 is connected to a scum pit 3, and wastewater containing scum (scum water) is collected in the scum pit 3, and then sent from the scum pit 3 to a scum screening unit 4 installed outside the settling tank 1 by a scum pump 31. The scum water collected in the scum pit 3 also contains impurities such as sediment. The scum screening unit 4 is provided with a scum impurity removal screening device 7. This scum impurity removal screen device 7 removes scum, which is impurities contained in the scum water. The wastewater from which the scum has been removed by this scum impurity removal screen device 7 is returned to the sewage treatment plant.

Next, the raw sludge screening unit 2 equipped with the raw sludge impurity removal screening device 6 will be described as an example, but the same applies to the scum screening unit 4 equipped with the scum impurity removal screening device 7. Both the raw sludge impurity removal screening device 6 and the scum impurity removal screening device 7 are examples of impurity removal screening devices.

Figure 2 is a front view of a raw sludge screen unit equipped with a raw sludge impurity removal screen device according to this embodiment.

As shown in Figure 2, the raw sludge screening unit 2 includes a water tank 5 and a raw sludge impurity removal screening device 6. The raw sludge screening unit 2 shown in Figure 2 receives raw sludge from the left side of the figure (see the thick arrow in the figure). Hereinafter, the left side in Figure 2 will be referred to as the upstream side, and the right side as the downstream side. Also, the direction perpendicular to the paper surface in Figure 2 will be referred to as the width direction. The raw sludge impurity removal screening device 6 includes a screen body 60, which will be described in detail later. In Figure 2, only the upstream side of the screen body 60 is shown by a thick dashed line.

In the lower half of the upstream side wall of the water tank 5 shown in FIG. 2, there is a slope 51 that slopes downstream as it approaches the bottom 5a, and in the lower half of the downstream side wall, there is a slope 52 that slopes upstream as it approaches the bottom 5a. Therefore, the water tank 5 has a shape that is narrower on the bottom 5a side. This water tank 5 receives the sludge collected in the sludge pit 11 shown in FIG. 1 as raw sludge. An inlet pipe 53 is provided on the upstream side of the water tank 5. Raw sludge is supplied to the inlet pipe 53 by driving the sludge pump 13, flows into the water tank 5 from the tip 531 of the inlet pipe 53, and flows toward the downstream side (see the many thin arrows in the figure). When viewed from above, the tip 531 of the inlet pipe 53 is formed in a fan shape that widens as it approaches the downstream side. In addition, impurities X, such as screen residue, contained in the raw sludge are blocked by the screen body 60 of the raw sludge impurity removal screen device 6, and are left to accumulate near the water surface upstream of the screen body 60.

In the raw sludge screen unit 2, an emergency overflow unit 54 is provided upstream of the screen body 60 in the raw sludge impurity removal screen device 6. A wastewater overflow unit 55 is provided downstream of the screen body 60. Both the emergency overflow unit 54 and the wastewater overflow unit 55 have drainage manholes 541, 551 and dam panels 542, 552. These drainage manholes 541, 551 are both provided to protrude outward in the width direction of the water tank 5. The dam panel 552 of the wastewater overflow unit 55 is provided at the boundary between the water tank 5 and the drainage manhole 551, and the water tank 5 and the drainage manhole 551 are connected above the dam panel 552, but are not connected below the dam panel 552. When the water level in the water tank 5 exceeds the height position of the upper end of the dam plate 552, the wastewater in the water tank 5 flows over the dam plate 552 into the drainage basin 551. The wastewater in the water tank 5 here is raw sludge that has passed through the screen body 60, that is, wastewater containing sludge from which impurities have been removed by the raw sludge impurity removal screen device 6, and this wastewater is sent to the sludge concentration treatment equipment and sludge dewatering treatment equipment, which are post-treatment equipment. In this way, the raw sludge that has passed through the screen body 60 provided in the raw sludge impurity removal screen device 6 is drained outside the raw sludge screen unit 2 by the drainage overflow unit 55.

The structure of the emergency overflow unit 54 is the same as that of the wastewater overflow unit 55, but the emergency overflow unit 54 is located at a higher position than the wastewater overflow unit 55. When the raw sludge impurity removal screen device 6 breaks down, for example, and the water level in the water tank 5 rises from the normal water level and exceeds the dam plate 542 of the emergency overflow unit 54, the water flows into the drainage basin 541 of the emergency overflow unit 54. The raw sludge in the water tank 5 here refers to raw sludge before it passes through the screen body 60, that is, wastewater containing sludge before impurities are removed by the raw sludge impurity removal screen device 6, and this wastewater is returned to the upstream end of the raw sludge impurity removal screen device 6.

Next, the raw sludge impurity removal screen device 6 will be described. The raw sludge impurity removal screen device 6 has a screen body 60, a base frame 64, and a drive device 65. The base frame 64 is attached to a pair of support legs 69 fixed to the edge of the water tank 5. Note that while one of the pair of support legs 69 is shown in FIG. 2, the other support leg 69 is fixed to the opposite edge of the water tank 5, sandwiching the raw sludge impurity removal screen device 6 in the width direction. The base frame 64 and the support leg 69 are rotatably connected by a rotating shaft 69a, and are fixed at the angle shown in FIG. 2 by a bolt (not shown).

The screen body 60 is disposed in the water tank 5 in an inclined position so that its lower portion is located on the upstream side of the water tank 5 and its upper portion is located on the downstream side. The top of the screen body 60 is located above the dam plate 542 of the emergency overflow unit 54.

Figure 3 is a cross-sectional view of the raw sludge screen unit shown in Figure 2 taken along the line A-A. Also, Figure 4 is a front view of the raw sludge impurity removal screen device. In Figure 4, the cover 648 attached to the widthwise end of the raw sludge impurity removal screen device 6 is omitted from the illustration.

3, the screen body 60 is composed of a plurality of fixed screen members 61, a plurality of first operating screen members 62, and a plurality of second operating screen members 63. In FIG. 3, the fixed screen members 61, the first operating screen members 62, and a portion of the second operating screen members 63 are omitted in order to simplify the drawing. In this embodiment, the number of the first operating screen members 62 is the same as the number of the second operating screen members 63. The fixed screen members 61, the first operating screen members 62, and the second operating screen members 63 are each an elongated stainless steel member arranged at an incline so as to be located downstream as it goes upward. However, the fixed screen members 61, the first operating screen members 62, and the second operating screen members 63 may be made of other metals, resins, etc., or may be made of different materials, as long as they have excellent corrosion resistance and durability against raw sludge. The fixed screen members 61 are arranged side by side in the entire width direction, except for the central portion in the width direction, at intervals from each other. The first operating screen members 62 are arranged side by side in the width direction on the right half of the tank 5 as viewed from the upstream side, and the second operating screen members 63 are arranged side by side in the width direction on the left half of the tank 5 as viewed from the upstream side. Hereinafter, the right side of the tank 5 as viewed from the upstream side is referred to as the right side of the tank, and the left side of the tank 5 as viewed from the upstream side of the tank is referred to as the left side of the tank. Each of the multiple first operating screen members 62 is arranged between two fixed screen members 61. That is, the fixed screen members 61 and the first operating screen members 62 are alternately arranged at a predetermined interval W (for example, 2 mm or more and 6 mm or less) in the width direction over almost the entire right half of the tank. Similarly, each of the multiple second operating screen members 63 is arranged between two fixed screen members 61. That is, the fixed screen members 61 and the second operating screen members 63 are alternately arranged at a predetermined interval W in the width direction over almost the entire left half of the tank. The predetermined interval W is a distance between the upstream and downstream sides, which is set based on the balance between the flow rate of raw sludge passing through the raw sludge impurity removal screen device 6 and the size of the device. Impurities contained in the raw sludge that cannot pass through the predetermined interval W are captured by the screen body 60 so as to block the predetermined interval W on the upstream side of the screen body 60. Note that in FIG. 3, the widthwise thicknesses of the fixed screen member 61, the first movable screen member 62, and the second movable screen member 63, the distance between the fixed screen member 61 and the first movable screen member 62, and the distance between the fixed screen member 61 and the second movable screen member 63 are exaggerated.

A plurality of fixed steps 611 are provided along the longitudinal direction on the upstream side of the fixed screen member 61. A plurality of first operating steps 621 are provided along the longitudinal direction on the upstream side of the first operating screen member 62, and a plurality of second operating steps 631 are provided along the longitudinal direction on the upstream side of the second operating screen member 63. Here, the longitudinal direction of the fixed screen member 61, the longitudinal direction of the first operating screen member 62, and the longitudinal direction of the second operating screen member 63 are the directions in which the impurities are transported, as described below. That is, the fixed screen member 61, the first operating screen member 62, and the second operating screen member 63 are all provided with stair-like steps aligned in the direction of transport of the impurities. A fixed top step 612 is provided at the top of each of the plurality of fixed screen members 61. The fixed top step 612 is made of a separate member formed wider than the fixed step 611. The fixed top stage 612 maintains the distance between the fixed screen member 61 and the first movable screen member 62 or the distance between the fixed screen member 61 and the second movable screen member 63 at a predetermined distance W. The fixed top stage 612 is also located above the water surface of the raw sludge (sewage).

The base frame 64 includes a pair of end base plates 641, a pair of center base plates 642, two horizontal members 643 for fixed screens, a drive bearing 644, a driven bearing 645, a flow dividing plate 646, a cross plate 647 (see FIG. 4), and a pair of covers 648. The pair of end base plates 641 extend from the bottom 5a of the tank 5 to above the upper end of the tank 5 along the side wall surface of the tank 5 at both ends in the width direction of the tank 5. The pair of center base plates 642 are disposed in the center of the tank 5 in the width direction and extend from the bottom 5a of the tank 5 to above the upper end of the tank 5. The drive bearing 644 and the driven bearing 645 are disposed between the pair of center base plates 642. The pair of end base plates 641 and the pair of center base plates 642 have almost the same shape when viewed in the width direction. In FIG. 3, the cross plate 647 is omitted in order to show the internal structure, but the cross plate 647 is a plate-shaped member that extends in the width direction on both the right and left sides of the tank and connects the end base plate 641 and the central base plate 642. The drive bearing 644 and the driven bearing 645 are located in the center of the tank 5 in the width direction and are fixed to the cross plate 647.

Two fixed screen horizontal members 643 are hung between a pair of end base plates 641. Both ends in the width direction of each of the two fixed screen horizontal members 643 are fixed to the end base plate 641. Therefore, the two fixed screen horizontal members 643 connect the pair of end base plates 641. The fixed screen horizontal members 643 may be configured to be split at the center in the width direction. In the case of a split configuration, both ends of one split fixed screen horizontal member 643 may be fixed to the end base plate 641 on the right side of the tank and the center base plate 642 on the right side of the tank, and both ends of the other split fixed screen horizontal member 643 may be fixed to the end base plate 641 on the left side of the tank and the center base plate 642 on the left side of the tank. The fixed screen member 61 is fixed to the upstream side of this fixed screen horizontal member 643. Therefore, the fixed screen member 61 is fixed to a predetermined position of the water tank 5.

The flow dividing plate 646 is fixed to the central base plate 642 near the center of the width of the water tank 5. This flow dividing plate 646 corresponds to an example of a flow dividing member. The flow dividing plate 646 is composed of a stainless steel plate material whose downstream side is fixed to each of the pair of central base plates 642. The upstream end surface of the flow dividing plate 646 is bent in a U-shape protruding toward the upstream side so as to cover the space between the pair of central base plates 642 upstream of the screen body 60, and the downstream end of the flow dividing plate 646 reaches the screen body 60. This flow dividing plate 646 divides the raw sludge that has flowed from the upstream side toward the flow dividing plate 646 into the right side of the tank where the first operating screen member 62 is arranged and the left side of the layer where the second operating screen member 63 is arranged. This flow dividing plate 646 prevents raw sludge from flowing directly into the space between the pair of central base plates 642 from the upstream side of the screen body 60 together with impurities such as sediment. The flow dividing plate 646 prevents impurities from becoming entangled with the first driven eccentric cam 6541, the second driven eccentric cam 6542, the driven bearing 645, and the first frame 651 and second frame 652 (described below) located near the center in the width direction, and prevents impurities from passing through the central base plate 642.

The pair of covers 648 are positioned outside the pair of end base plates 641 and cover both widthwise end faces of the raw sludge impurity removal screen device 6. A rubber seal 6481 is attached to the upstream end face of the cover 648, protruding toward the side wall of the water tank 5 and extending from the bottom 5a to the upper end of the water tank 5. This rubber seal 6481 is intended to prevent impurities from slipping through the gap between the widthwise end faces of the raw sludge impurity removal screen device 6 and the side wall of the water tank 5 to the downstream of the raw sludge impurity removal screen device 6.

The drive unit 65 includes a first frame 651, a second frame 652, a drive shaft 653, a driven shaft 654, and an actuator 655. The first frame 651 is disposed on the right side of the tank. The first frame 651 includes a first right frame 651R, a first left frame 651L, and two cross members 6511 for the first operating screen. The first right frame 651R is disposed between the side wall on the right side of the tank 5 and the end base plate 641 on the right side of the tank. The first left frame 651L is disposed between a pair of center base plates 642. The first right frame 651R is shown in FIG. 4. The first left frame 651L is configured to be plane-symmetrical with the first right frame 651R with respect to a plane perpendicular to the width direction. As shown in FIG. 4, the first right frame 651R is composed of a plate-like member in which a triangular part having a generally triangular shape with a hollowed-out center when viewed from the width direction and an arm part extending from the triangular part toward the drive shaft 653 are integrally joined. Also, as shown in FIG. 3, two first moving screen horizontal members 6511 are hung between the first right frame 651R and the first left frame 651L. Both ends of each of the two first moving screen horizontal members 6511 in the width direction are fixed to the first right frame 651R and the first left frame 651L. Therefore, the two first moving screen horizontal members 6511 connect the first right frame 651R and the first left frame 651L. The first moving screen member 62 is fixed to the upstream side of the two first moving screen horizontal members 6511.

The second frame 652 is disposed on the left side of the tank. The second frame 652 includes a second right frame 652R, a second left frame 652L, and two second operating screen horizontal members 6521. The second left frame 652L is disposed between the side wall on the left side of the tank 5 and the end base plate 641 on the left side of the tank. The second right frame 652R is disposed between a pair of center base plates 642. Therefore, the first frame 651 and the second frame 652 are disposed with a gap in the width direction. The second frame 652 has the same shape as the first frame 651 except for the parts related to the second driving position 652a and the second driven position 652b described later. As shown in FIG. 3, the two second operating screen horizontal members 6521 are hung between the second right frame 652R and the second left frame 652L. Each of the two second moving screen cross members 6521 has both ends in the width direction fixed to the second right frame 652R and the second left frame 652L. Therefore, the two second moving screen cross members 6521 connect the second right frame 652R and the second left frame 652L. The second moving screen member 63 is fixed to the upstream side of the two second moving screen cross members 6521.

The drive shaft 653 and the driven shaft 654 are shafts extending in the width direction upstream of the screen body 60. Both ends of the drive shaft 653 and the driven shaft 654 pass through a pair of end base plates 641, respectively. The drive shaft 653 is rotatably supported on the base frame 64 by a bearing (not shown) and a drive bearing 644 fixed to the end base plate 641. A drive shaft suspending device 6533 is attached to the inner part of the pair of end base plates 641 near both ends of the drive shaft 653 in the width direction. The driven shaft 654 is rotatably supported on the base frame 64 by a bearing (not shown) and a driven bearing 645 fixed to the end base plate 641. A driven shaft suspending device 6543 is attached to the inner part of the pair of end base plates 641 near both ends of the driven shaft 654 in the width direction. The drive shaft suspending device 6533 and the driven shaft suspending device 6543 are parts to which hooks are attached when lifting the raw sludge impurity removal screen device 6 from the water tank 5 for maintenance, etc. The parts of the drive shaft 653 and the driven shaft 654 between the first right frame 651R and the first left frame 651L and between the second right frame 652R and the second left frame 652L are covered with protective pipes (not shown). The drive shaft suspending device 6533 and the driven shaft suspending device 6543 are integrally connected to the protective pipes.

The first frame 651 and the second frame 652 are driven by a common actuator 655. This actuator 655 includes a motor 6551 and a gear box 6552. The gear box 6552 converts the driving force (rotational force) generated by the motor 6551 and the driving direction (rotation direction). The gear box 6552 is connected to the driving shaft 653. The driving force generated by the motor 6551 is transmitted to the driving shaft 653 via the gear box 6552 and acts as a force to rotate the driving shaft 653. However, the motor 6551 may be fixed to the end base plate 641 so that the axial direction of the output shaft coincides with the width direction, and the gear box 6552 may be omitted to directly connect the output shaft and the driving shaft 653. In this case, only the motor 6551 corresponds to an example of an actuator. Similarly, the motor 6551 may be fixed to the end base plate 641 so that the axial direction of the output shaft coincides with the width direction, and the output shaft and the drive shaft 653 may be connected by a mechanical transmission element such as a chain that does not change the driving direction. In this case, the motor 6551 and the mechanical transmission element are an example of an actuator.

The first frame 651 is supported by two first driving eccentric cams 6531 fixed to the driving shaft 653 and two first driven eccentric cams 6541 fixed to the driven shaft 654. The first right frame 651R and the first left frame 651L are each rotatably connected to the first driving eccentric cam 6531 at a first driving position 651a (see FIG. 4) eccentric to the driving axis 653a, which is the axis of the driving shaft 653. Specifically, the first right frame 651R and the first driving eccentric cam 6531 are connected by inserting an unillustrated shaft protruding in the width direction from the first driving eccentric cam 6531 into an unillustrated hole formed in the first right frame 651R. The first left frame 651L is also connected to the first driving eccentric cam 6531 in a similar configuration. In addition, each of the first right frame 651R and the first left frame 651L is connected to the first driven eccentric cam 6541 so as to be rotatable at a first driven position 651b (see FIG. 4) that is eccentric with respect to the driven shaft center 654a, which is the shaft center of the driven shaft 654. Specifically, the first right frame 651R and the first driven eccentric cam 6541 are connected by inserting an unillustrated shaft protruding in the width direction from the first driven eccentric cam 6541 into an unillustrated hole formed in the first right frame 651R. The first left frame 651L is also connected to the first driven eccentric cam 6541 in a similar configuration. Here, the relative position between the drive shaft center 653a and the first drive position 651a and the relative position between the driven shaft center 654a and the first driven position 651b have the same positional relationship.

When the actuator 655 is driven, the driving force is transmitted from the drive shaft 653 to the first frame 651 via the first drive eccentric cam 6531. As a result, the first frame 651 rotates while maintaining its posture in a circular orbit with a radius equal to the distance between the drive shaft center 653a and the first drive position 651a and the distance between the driven shaft center 654a and the first driven position 651b when viewed in the width direction. At this time, the first operating screen member 62 also rotates together with the first frame 651.

The second frame 652 is supported by two second driving eccentric cams 6532 fixed to the driving shaft 653 and two second driven eccentric cams 6542 fixed to the driven shaft 654. The second right frame 652R and the second left frame 652L are each rotatably connected to the second driving eccentric cam 6532 at a second driving position 652a (see FIG. 4) eccentric to the driving shaft center 653a. Specifically, the second right frame 652R and the second driving eccentric cam 6532 are connected by inserting an unillustrated shaft protruding in the width direction from the second driving eccentric cam 6532 into an unillustrated hole formed in the second right frame 652R. The second left frame 652L is also connected to the second driving eccentric cam 6532 in a similar configuration. The second driving position 652a is a position rotated 180 degrees around the driving axis 653a with respect to the first driving position 651a. The second right frame 652R and the second left frame 652L are each rotatably connected to the second driven eccentric cam 6542 at a second driven position 652b (see FIG. 4) eccentric to the driven axis 654a. Specifically, the second right frame 652R and the second driven eccentric cam 6542 are connected to each other by inserting a shaft (not shown) protruding in the width direction from the second driven eccentric cam 6542 into a hole (not shown) formed in the second right frame 652R. The second left frame 652L is also connected to the second driven eccentric cam 6542 in a similar configuration. Here, the relative position between the drive shaft center 653a and the second drive position 652a and the relative position between the driven shaft center 654a and the second driven position 652b have the same positional relationship.

When the actuator 655 is driven, the driving force is transmitted from the drive shaft 653 to the second frame 652 via the second drive eccentric cam 6532. As a result, the second frame 652 rotates while maintaining its posture in a circular orbit with a radius equal to the distance between the drive shaft center 653a and the second drive position 652a and the distance between the driven shaft center 654a and the second driven position 652b when viewed in the width direction. At this time, the second operating screen member 63 also rotates together with the second frame 652.

Next, we will explain the operation of the first movable screen member 62 and the second movable screen member 63 in the raw sludge impurity removal screen device 6.

Figure 5 is a diagram showing the steps of the operation of the first and second operating screen members. In this figure, the shapes of the fixed screen member 61, the first operating screen member 62, and the second operating screen member 63 are simplified, and the number of fixed step portions 611, first operating step portions 621, and second operating step portions 631 is reduced. In addition, the first operating screen member 62 and the second operating screen member 63 are shown in two rows, upper and lower, so that the operation of each is easy to understand. In Figure 5, the agreement of the numbers (a1) to (a5) in the upper row and (b1) to (b5) in the lower row indicates a state at the same timing. The upper row of Figure 5 shows the fixed screen member 61, the first operating screen member 62, the drive shaft center 653a, and the first drive position 651a. The lower row of Figure 5 shows the fixed screen member 61, the second operating screen member 63, the drive shaft center 653a, and the second drive position 652a. In Figure 5, the left side of the figure is the upstream side, and the right side of the figure is the downstream side.

(a1) and (b1) show the first operating screen member 62 in the first initial position and the second operating screen member 63 in the second conveying position. Note that FIG. 3 is a cross-sectional view of the state in (a1) and (b1) seen from the upstream side. As shown in (a1), the lower part of the fixed screen member 61 is located very close to the bottom 5a, and the lower part of the first operating screen member 62 in the initial position is also located very close to the bottom 5a. When viewed from the width direction, the fixed screen member 61 and the first operating screen member 62 overlap, except for the fixed top stage 612 of the fixed screen member 61. In addition, impurities X1 are caught from the first operating stage 621, which is the ninth stage from the bottom of the first operating screen member 62 shown in (a1), to the fixed stage 611, which is also the ninth stage from the bottom, of the adjacent fixed screen member 61. The height position of the first operating step 621, which is the ninth step from the bottom of the first operating screen member 62 shown in (a1), coincides with the height position of the fixed step 611, which is also the ninth step from the bottom of the fixed screen member 61.

At this time, as shown in (b1), the second operating screen member 63 has moved exactly one step upward with respect to the fixed screen member 61, and when viewed from the width direction, it overlaps with the fixed screen member 61 except for its upper and lower end portions. In addition, impurities X2 are caught from the second operating step portion 631, which is the eighth step from the bottom of the second operating screen member 63 shown in (b1), to the fixed step portion 611, which is the ninth step from the bottom of the adjacent fixed screen member 61. The height position of the second operating step portion 631, which is the eighth step from the bottom of the second operating screen member 63 shown in (b1), matches the height position of the fixed step portion 611, which is the ninth step from the bottom of the fixed screen member 61.

As described above, when the actuator 655 shown in FIG. 3 is driven, the drive shaft 653, the first drive eccentric cam 6531, and the second drive eccentric cam 6532 rotate, causing the first frame 651 and the second frame 652 to rotate. In response to the rotation, the driven shaft 654, the first driven eccentric cam 6541, and the second driven eccentric cam 6542 also rotate. As the first frame 651 and the second frame 652 rotate, the first operating screen member 62 and the second operating screen member 63 move in a circular orbit between the fixed screen member 61 when viewed in the width direction. That is, the first operating screen member 62 and the second operating screen member 63 repeatedly move upward and downward while moving upstream and downstream relative to the fixed screen member 61.

(a2) and (b2) show the state when the drive shaft 653 rotates 90 degrees from the state of (a1) and (b1). As shown in (a2), the first drive position 651a rotates with respect to the drive shaft center 653a, and the first operating screen member 62 moves upward with respect to the fixed screen member 61. The debris X1 also moves upward with the first operating screen member 62 with respect to the fixed step portion 611, which is the ninth step from the bottom. Also, as shown in (b2), the second drive position 652a rotates with respect to the drive shaft center 653a, and the second operating screen member 63 moves downward with respect to the fixed screen member 61. The debris X2 is left behind in the fixed step portion 611, which is the ninth step from the bottom. That is, the drive device 65 moves the second operating screen member 63 downward while moving the first operating screen member 62 upward.

(a3) and (b3) show the state when the drive shaft 653 is rotated by another 90 degrees from the state of (a2) and (b2). As shown in (a3), the first operating screen member 62 moves downstream relative to the fixed screen member 61, and when viewed from the width direction, it is in the first conveying position overlapping the fixed screen member 61 except for the upper end part and the lower end part in a state where it has moved exactly one step upward relative to the fixed screen member 61. That is, the height position of the first operating step part 621, which is the ninth step from the bottom of the first operating screen member 62 shown in (a3), coincides with the height position of the fixed step part 611, which is the tenth step from the bottom of the fixed screen member 61. And the impurities X1 are lifted one step by the first operating screen member 62 and are caught on the fixed step part 611, which is the tenth step from the bottom of the fixed screen member 61. In this way, the debris X1 caught on the ninth first operating step 621 is transferred to the tenth fixed step 611 by the movement of the first operating screen member 62. Also, as shown in (b3), the second operating screen member 63 moves upstream relative to the fixed screen member 61, and is in the second initial position where the fixed screen member 61 and the second operating screen member 63 overlap when viewed in the width direction. That is, the driving device 65 moves the second operating screen member 63 upstream when the first operating screen member 62 moves downstream. Also, as shown in (a1) and (b1) to (a3) and (b3), the driving device 65 returns the second operating screen member 63 toward the second initial position when the first operating screen member 62 is moved toward the first transport position.

(a4) and (b4) show the state when the drive shaft 653 is rotated another 90 degrees from the state of (a3) and (b3). As shown in (a4), the first operating screen member 62 is moving downward relative to the fixed screen member 61. The debris X1 is left behind on the fixed step 611, which is the 10th step from the bottom. Also, as shown in (b4), the second operating screen member 63 is moving upward relative to the fixed screen member 61. The debris X2, together with the second operating screen member 63, is also moving upward relative to the fixed step 611, which is the 9th step from the bottom. That is, the drive device 65 moves the second operating screen member 63 upward while moving the first operating screen member 62 downward.

(a5) and (b5) show the state when the drive shaft 653 is rotated by another 90 degrees from the state of (a4) and (b4). As shown in (a5), the first operating screen member 62 moves upstream relative to the fixed screen member 61, and the fixed screen member 61 and the first operating screen member 62 overlap when viewed from the width direction. That is, the first operating screen member 62 shown in (a5) has returned to the same first initial position as (a1). Also, as shown in (b5), the second operating screen member 63 moves downstream relative to the fixed screen member 61, and overlaps the fixed screen member 61 except for the upper end portion and the lower end portion when viewed from the width direction in a state where it has moved exactly one step upward relative to the fixed screen member 61. That is, the first operating screen member 62 shown in (b5) has returned to the same second conveying position as (b1). Also, as shown in (a3) and (b3) to (a5) and (b5), the drive device 65 moves the second operating screen member 63 toward the second transport position while the first operating screen member 62 is returning toward the first initial position.

As shown in FIG. 5, one cycle of driving the first movable screen member 62 from (a1) to (a5), and one cycle of driving the second movable screen member 63 from (b1) to (b5) are repeatedly performed at a speed of, for example, about 13 cycles per minute during a predetermined operating period according to the number of stages of the fixed stage portion 611 of the fixed screen member 61, etc.

As described above, during operation, the impurities X1 and X2 are transported upward one step at a time along the fixed stage 611 on the upstream side of the screen body 60, and ultimately slide down from the top stage 612 toward a chute (not shown) on the downstream side, and are discharged outside the raw sludge impurity removal screen device 6.

According to this embodiment, the first operating screen member 62 and the second operating screen member 63 are configured to move upward and downward at different timings with a lag, so that the load on the driving device 65 is reduced. As a result, the raw sludge impurity removal screen device 6 can be driven with less power. In addition, the rotational movement of the first operating screen member 62 and the second operating screen member 63 becomes smooth, so that the vibration of the raw sludge impurity removal screen device 6 can be suppressed. Moreover, in this embodiment, the driving device 65 moves the second operating screen member 63 downward when the first operating screen member 62 is moved upward, and moves the first operating screen member 62 downward when the second operating screen member 63 is moved upward. This allows the weight of the first operating screen member 62 and the weight of the second operating screen member 63 to be offset, and the load on the driving device 65 is further reduced. In other words, when one of the first and second operating screen members 62 and 63 is moving upward, the weight of the other acts as a force to assist the driving of the driving device 65, so the load on the driving device 65 can be further reduced. This allows the raw sludge impurity removal screen device 6 to be driven with less power. In addition, the balance of the load on the driving device 65 due to the weights of the first and second operating screen members 62 and 63 becomes almost uniform, so the rotational motion of the driving device 65 becomes smooth and vibration due to driving is further reduced. Furthermore, the first frame 651 and the second frame 652 are arranged with a gap in the width direction, and the operating area of the first operating screen member 62 and the operating area of the second operating screen member 63 do not overlap, so the configuration of the driving device 65 can be simplified.

The present invention is not limited to the above-mentioned embodiment, and various modifications can be made within the scope of the claims. For example, in the above-mentioned embodiment, the raw sludge impurity removal screen device 6 and the scum impurity removal screen device 7 provided in the raw sludge screen unit 2 are described as examples, but the present invention is not limited to sewage treatment facilities, and can also be applied to facilities that treat water such as industrial water and agricultural water. In addition, in the above-mentioned embodiment, the impurity removal screen device installed in the water tank 5 is described as an example, but the impurity removal screen device may be installed in sewage flowing through the flow path. Furthermore, the driving device 65 has been described as an example in which the first operating screen member 62 and the second operating screen member 63 are moved in a circular orbit when viewed from the width direction, but it may be configured to move in a polygonal shape such as a rectangular shape using a link mechanism or the like. Furthermore, in this embodiment, the operating screen member is divided into two, the first operating screen member 62 and the second operating screen member 63, and driven with a shift in the timing of moving them upward, but it may be divided into three or more and driven with a shift in the timing of moving them upward. That is, if the timing of moving at least one of the operating screen members upward is made different from the timing of moving the other operating screen members upward, the driving load can be reduced compared to the case where all the operating screen members move up and down at the same timing. However, it is preferable to set the timing of moving each operating screen member upward so that the driving load of the driving device 65 is uniform within one cycle, taking into account the total weight of each driving screen member and the frame that drives the driving screen member, because this will further enhance the power consumption reduction effect and vibration suppression effect. In addition, in this embodiment, the first operating screen member 62 and the second operating screen member 63 are arranged separately on the right side of the tank and the left side of the tank, but they may be arranged separately above and below the raw sludge impurity removal screen device 6. In addition, the fixed screen member 61, the first operating screen member 62, and the second operating screen member 63 may be arranged in any order. For example, multiple sets of the first operating screen member 62, the fixed screen member 61, the second operating screen member 63, and the fixed screen member 61 may be arranged in this order in the width direction. Furthermore, in this embodiment, the driving device 65 moves the first operating screen member 62 and the second operating screen member 63 upward and downward, but the first operating screen member 62 and the second operating screen member 63 may move downward by their own weight, and the driving device 65 may move only upward.

The above-described impurity removal screen device includes a plurality of fixed screen members provided at intervals,
a first movable screen member and a second movable screen member that repeatedly move upward and downward between the plurality of fixed screen members to transport impurities upward;
a drive device for moving the first movable screen member and the second movable screen member upward;
The driving device comprises a first frame that holds a plurality of the first operating screen members, a second frame that holds a plurality of the second operating screen members, a drive shaft that transmits driving force to each of the first frame and the second frame, and an actuator that drives the drive shaft, and is characterized in that by driving the first frame and the second frame, the plurality of first operating screen members and the plurality of second operating screen members are moved upward with staggered timing.

In this impurity removal screen device, the first frame has a pair of left and right first frame parts arranged with a gap in the width direction, and a first cross member connecting the first frame parts,
a plurality of the first movable screen members fixed to the first cross member;
The second frame includes a pair of left and right second frame portions arranged at an interval in the width direction, and a second cross member connecting the second frame portions,
The second plurality of moving screen members may be fixed to the second cross member.

Also, a plurality of fixed screen members provided at intervals;
a first movable screen member and a second movable screen member that repeatedly move upward and downward between the plurality of fixed screen members to transport impurities upward;
a drive device for moving the first movable screen member and the second movable screen member upward;
The drive device may be configured to move the first movable screen member and the second movable screen member upward with a timing difference.

This impurity removal screen device reduces the load on the drive device, allowing the impurity removal screen device to be driven with less power.

The drive device may be configured to move the second operating screen member downward when the first operating screen member is being moved upward, and to move the second operating screen member upward when the first operating screen member is being moved downward. The drive device may also be configured to move the first operating screen member and the second screen member in a circular orbit.

In addition, in this impurity removal screen device, the drive device may be configured to include a first frame that holds the first movable screen member, a second frame that holds the second movable screen member, a drive shaft that transmits a drive force to each of the first frame and the second frame, and an actuator that drives the drive shaft.

According to this aspect, the driving force of the actuator can be transmitted to the first frame and the second frame with a simple configuration, and the first screen member and the second movable screen member can be moved, respectively.

Furthermore, in this impurity removal screen device, the fixed screen member is arranged in a plurality of members in the width direction,
The first frame and the second frame may be disposed with a gap therebetween in the width direction.

This allows the drive device to be configured more simply.

In addition, this impurity removal screen device may be provided with a diversion member that diverts the received wastewater flowing toward the gap between the side where the first movable screen member is positioned and the side where the second movable screen member is positioned.

The flow diverter member can prevent impurities from entering the gap and passing through the impurity removal screen device.
The above-described impurity removal screen device includes a plurality of fixed screen members provided at intervals and having fixed stepped portions in a stepped shape;
a first movable screen member having a stepped first movable step portion and a second movable screen member having a stepped second movable step portion, which move upward between the plurality of fixed screen members by repeatedly moving upward and downward;
a drive device for moving the first movable screen member and the second movable screen member upward;
The driving device is characterized by having a common actuator that moves the first movable screen member and the second movable screen member upward with a timing difference.
In this impurity removal screen device, the number of the first movable screen members may be the same as the number of the second movable screen members.

Reference Signs List 2 Raw sludge screen unit 4 Scum screen unit 5 Water tank 6 Raw sludge impurity removal screen device 7 Scum impurity removal screen device 61 Fixed screen member 62 First movable screen member 63 Second movable screen member 65 Drive device

Claims (2)

a plurality of first fixed screen members provided at intervals from each other in the width direction and having step-like first fixed step portions;
a plurality of first movable screen members each having a stepped first movable step portion that is arranged alternately with the plurality of first fixed screen members in the width direction and repeatedly moves upward and downward to transfer the impurities to the upper first fixed step portion, thereby transporting the impurities upward ;
a plurality of second fixed screen members provided at intervals from each other in the width direction and having stepped second fixed step portions;
a plurality of second movable screen members each having a stepped second movable step portion that is arranged alternately with the plurality of second fixed screen members in the width direction and repeatedly moves upward and downward to transfer the impurities to the upper second fixed step portion, thereby transporting the impurities upward ;
a first screen group consisting of a plurality of the first fixed screen members and a plurality of the first movable screen members, and a second screen group consisting of a plurality of the second fixed screen members and a plurality of the second movable screen members are arranged to be spaced apart in the width direction,
a drive device for moving the first movable screen members and the second movable screen members upward;
The impurity removal screen device is characterized in that the driving device has a common actuator that moves the multiple first movable screen members and the multiple second movable screen members upward at different times. 2. The impurity removal screen device according to claim 1, wherein the number of the first movable screen members is equal to the number of the second movable screen members.

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