Impurity removing screen device

Abstract

To provide an impurity removing screen device capable of efficiently transferring impurities.SOLUTION: An impurity removing screen device 6 for raw sludge includes a plurality of first movable screen members 61 which are arranged with a distance in a thickness direction, have a plurality of first stage parts 611 in a transfer direction of impurities X, and are repeatedly moved to upper and lower sides, a plurality of second movable screen members 62 which are arranged between the first movable screen members 61, have a plurality of second stage parts 621 in the transfer direction of the impurities X and are repeatedly moved to the upper and lower sides, and a driving mechanism 65 having a first frame 651 to which the plurality of first movable screen members 61 are fixed and a second frame 652 to which the plurality of second movable screen members 62 are fixed, wherein the driving mechanism 65 moves a first frame 651 and a second frame 652, and thereby moves the first movable screen members 61 and the second movable screen members 62 to the upper and lower sides at different timings.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an impurity removal screen device that transfers impurities contained in sewage upward.

Background Art

[0002] In a sewage treatment system, generally, sewage consisting of sewage flows and is purified in the order of a grit chamber, a primary sedimentation tank, a reaction tank, and a final sedimentation tank. Among these, for example, in the primary sedimentation tank, sewage (raw sludge) containing sludge settled at the bottom of the tank is transferred outside the primary sedimentation tank by a sludge pump or the like, concentrated, dehydrated, and then incinerated. Here, since the raw sludge contains impurities such as scum, generally, before being concentrated and dehydrated, the impurities are removed from the raw sludge by an impurity removal screen device for raw sludge. Also, sewage (scum water) containing scum of impurities floating near the water surface of the primary sedimentation tank is collected in a scum pit, and then transferred outside the primary sedimentation tank from the scum pit by a scum pump. The scum water transferred outside the primary sedimentation tank is returned to the sewage treatment plant after the scum is removed by a scum removal screen device. These impurity removal screen devices are arranged in a water tank that receives raw sludge and scum water from the primary sedimentation tank (see, for example, Patent Document 1 and Patent Document 2).

[0003] The impurity removal screen device described in Patent Document 1 and Patent Document 2 includes a plurality of fixed screen members and an operating screen member disposed between these plurality of fixed screen members. The fixed screen members each extend obliquely upward, and the uppermost part protrudes from the water surface of the water tank. Also, the fixed screen members have a stepped shape in which a plurality of fixed step portions are arranged side by side in the extending direction. The operating screen member also extends obliquely upward and has a stepped shape in which a plurality of operating step portions are arranged side by side in the extending direction. The operating screen member transfers impurities toward the uppermost part of the fixed screen member by repeatedly moving upward and downward with respect to the fixed screen member.

Prior Art Documents

Patent Document

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The foreign matter removal screen device described in Patent Document 1 and Patent Document 2 transfers foreign matter onto one step of the fixed step portion of the fixed screen member by moving the operating screen member one cycle upward and downward. Therefore, in order to transfer foreign matter to the uppermost part of the fixed screen member, it is necessary to move the operating screen member a large number of cycles. However, in recent years, there has been a demand for a foreign matter removal screen device that can transfer foreign matter more efficiently.

[0006] In view of the above circumstances, an object of the present invention is to provide a foreign matter removal screen device that can transfer foreign matter efficiently.

Means for Solving the Problems

[0007] The foreign matter removal screen device of the present invention for solving the above problems is a foreign matter removal screen device that transfers foreign matter contained in sewage upward. A plurality of first operating screen members that are arranged at a distance in the thickness direction, provided with a plurality of steps in the transfer direction of foreign matter, and repeatedly move upward and downward. A plurality of second operating screen members that are arranged between the first operating screen members, provided with a plurality of steps in the transfer direction of foreign matter, and repeatedly move upward and downward. A drive mechanism having a first frame to which a plurality of the first operating screen members are fixed and a second frame to which a plurality of the second operating screen members are fixed. The drive mechanism may be characterized in that by moving the first frame and the second frame, the first operating screen member and the second operating screen member are moved upward and downward at different timings.

[0008] Further, in the foreign matter removal screen device of the present invention, the drive mechanism may be configured to include a common actuator that moves the first operating screen member and the second operating screen member upward and downward, respectively.

[0009] Furthermore, in the foreign matter removal screen device of the present invention, the first operating screen member and the second operating screen member may be alternately arranged.

Advantages of the Invention

[0010] According to the present invention, it is possible to provide a foreign matter removal screen device capable of efficiently transferring foreign matters.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0013] FIG. 1 is a diagram schematically showing some facilities in a sewage treatment plant. In this FIG. 1, a sedimentation tank 1, a raw sludge screen unit 2, a scum pit 3, and a scum screen unit 4 are shown.

[0014] The sedimentation tank 1 shown in Fig. 1 receives sewage (wastewater) from one end side in the longitudinal direction (the left side in Fig. 1), precipitates the sludge contained in the received sewage at the bottom of the tank, and discharges water from the other end side (the right side in Fig. 1). Hereinafter, the left direction in Fig. 1 is referred to as the upstream, and the right direction in Fig. 1 is referred to as the downstream. A sludge pit 11 is provided at the bottom of the upstream side of the sedimentation tank 1, and a drain gutter 12 is installed near the water surface on the downstream side. In the sedimentation tank 1, the sludge precipitated at the bottom of the tank is collected in the sludge pit 11 by a sludge scraping machine (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 scum. Hereinafter, the sewage containing sludge sent from the sludge pit 11 to the raw sludge screen unit 2 may be referred to as raw sludge. The raw sludge screen unit 2 is provided with a raw sludge impurity removal screen device 6. As will be described in detail later, the impurities contained in the raw sludge are removed by this raw sludge impurity removal screen device 6. The raw sludge from which impurities have been removed by the raw sludge impurity removal screen device 6 is then sent to a sludge thickening treatment facility or a sludge dewatering treatment facility. Also, in the sedimentation tank 1, the scum floating near the water surface is scraped by a scum scraping machine (not shown) to the drain gutter 12. The drain gutter 12 is connected to a scum pit 3, and the sewage containing scum (scum water) is collected in the scum pit 3, and then sent from the scum pit 3 by a scum pump 31 to a scum screen unit 4 installed outside the sedimentation tank 1. The scum water collected in the scum pit 3 also contains impurities such as scum. The scum screen unit 4 is provided with a scum impurity removal screen device 7. By this scum impurity removal screen device 7, the scum, which is the impurity contained in the scum water, is removed. The sewage from which scum has been removed by this scum impurity removal screen device 7 is returned to the wastewater treatment plant.

[0015] Next, the sludge screen unit 2 provided with the impurity removal screen device 6 for raw sludge will be described as an example. The same applies to the scum screen unit 4 provided with the impurity removal screen device 7 for scum. These impurity removal screen devices 6 for raw sludge and 7 for scum both correspond to an example of the impurity removal screen device. Also, the sludge screen unit 2 and the scum screen unit 4 both correspond to an example of the screen unit.

[0016] FIG. 2 is a front view of the sludge screen unit provided with the impurity removal screen device for raw sludge according to the present embodiment.

[0017] As shown in FIG. 2, the sludge screen unit 2 includes a water tank 5 and an impurity removal screen device 6 for raw sludge. The sludge screen unit 2 shown in FIG. 2 receives raw sludge from the left side of the figure (see the thick arrow in the figure). Hereinafter, the left side in FIG. 2 is referred to as the upstream side, and the right side is referred to as the downstream side. Also, in FIG. 2, the direction orthogonal to the paper surface is referred to as the width direction. The impurity removal screen device 6 for raw sludge includes a screen body 60, which will be described in detail later. In FIG. 2, only the upstream side surface of the screen body 60 is shown by a thick broken line.

[0018] On the lower approximately half of the upstream side wall of the water tank 5 shown in Fig. 2, an inclined portion 51 that is inclined downstreamward toward the bottom 5a is provided, and on the lower approximately half of the downstream side wall, an inclined portion 52 that is inclined upstreamward toward the bottom 5a is provided. Therefore, the water tank 5 has a shape with a narrower bottom 5a side. This water tank 5 receives the sludge collected in the sludge pit 11 shown in Fig. 1 as raw sludge. An inflow pipe 53 is provided on the upstream side of the water tank 5. The raw sludge is supplied to the inflow pipe 53 by driving the sludge pump 13, flows into the water tank 5 from the tip portion 531 of this inflow pipe 53, and flows toward the downstream side (refer to the numerous thin arrows in the figure). Note that the tip portion 531 of the inflow pipe 53 is formed in a fan shape that expands as it goes downstream when viewed from above. Also, impurities X such as scum contained in the raw sludge are blocked by the screen body 60 provided in the raw sludge impurity removal screen device 6 and accumulate near the water surface on the upstream side of the screen body 60. The screen body 60 is driven by a motor 654 controlled by a control unit 66. This motor 654 corresponds to an example of an actuator. A gearbox 655 is attached to the motor 654. The gearbox 655 is fixed to a mounting table 56 formed at the upper end portion on the downstream side of the water tank 5.

[0019] The raw sludge screen unit 2 is provided with an emergency overflow unit 54 upstream of the screen body 60 in the raw sludge impurity removal screen device 6. Also, a drainage overflow unit 55 is provided downstream of the screen body 60. Both the emergency overflow unit 54 and the drainage overflow unit 55 have drainage troughs 541, 551 and weir plates 542, 552. These drainage troughs 541, 551 are both provided so as to project outward in the width direction of the water tank 5. The weir plate 552 of the drainage overflow unit 55 is provided at the boundary between the inside of the water tank 5 and the inside of the drainage trough 551. The inside of the water tank 5 and the inside of the drainage trough 551 are connected at a portion above the weir plate 552 and are not connected at a portion below the upper end of the weir plate 552. When the water level of the water tank 5 exceeds the height position of the upper end of the weir plate 552, the sewage in the water tank 5 flows over the weir plate 552 and into the drainage trough 551. The sewage in the water tank 5 here is the raw sludge that has passed through the screen body 60, that is, the sewage containing the sludge from which the impurities X have been removed by the raw sludge impurity removal screen device 6. This sewage is sent to the sludge thickening treatment facility and the sludge dewatering treatment facility, which are facilities in the post-treatment process. 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.

[0020] The structure of the emergency overflow unit 54 is the same as that of the drainage overflow unit 55, but the emergency overflow unit 54 is provided at a higher position than the drainage overflow unit 55. When the raw sludge impurity removal screen device 6 fails or the like and the water level of the water tank 5 rises from the normal water level and exceeds the weir plate 542 of the emergency overflow unit 54, the raw sludge in the water tank 5 flows into the drainage trough 541 of the emergency overflow unit 54. The raw sludge in the water tank 5 here is the raw sludge before passing through the screen body 60, that is, the sewage containing the sludge before the impurities are removed by the raw sludge impurity removal screen device 6. This sewage is returned to the upstream end of the raw sludge impurity removal screen device 6.

[0021] Next, the raw sludge contaminant removal screen device 6 will be described. The raw sludge contaminant removal screen device 6 includes a screen body 60, a base frame 64, a drive mechanism 65, a control unit 66, and a chute 67. The screen body 60 is disposed inside the base frame 64, and the upper portion of the upstream end of the base frame 64 is covered by a front cover 641 with a handle 6411. This front cover 641 is detachable from the base frame 64. The base frame 64 is attached to a pair of support legs 59 fixed to the edge of the water tank 5. Although only one of the pair of support legs 59 is shown in FIG. 2, the other support leg 59 is fixed to the opposite edge of the water tank 5 with the raw sludge contaminant removal screen device 6 sandwiched in the width direction. The base frame 64 is rotatably connected to the support leg 59 by a support shaft 59a and is fixed at the angle shown in FIG. 2 by bolts (not shown). The configuration of the base frame 64 will be further described later.

[0022] The screen body 60 is disposed in the water tank 5 in an inclined posture such that the lower part is located on the upstream side of the water tank 5 and the upper part is located on the downstream side. The uppermost part of this screen body 60 is located above the weir plate 542 of the emergency overflow unit 54. As will be described in detail later, by repeatedly moving the screen body 60 upward and downward, the contaminants X are transferred to the uppermost part of the screen body 60. Then, the contaminants X that reach the uppermost part of the screen body 60 are dropped into the chute 67. The chute 67 has a discharge port 671 that opens outside the raw sludge contaminant removal screen device 6. The contaminants X dropped into the chute 67 are discharged from the discharge port 671.

[0023] FIG. 3 is a cross-sectional view taken along line A-A of the raw sludge screen unit shown in FIG. 2. FIG. 4 is a front view of the raw sludge contaminant removal screen device shown in FIG. 2. In FIG. 3, a part of the base frame 64 is not shown. In FIG. 4, the motor 654 and the gear box 655 shown in FIG. 2 are not shown.

[0024] As shown in FIG. 3, the screen body 60 is composed of a plurality of first operating screen members 61 and a plurality of second operating screen members 62. The first operating screen members 61 are arranged at a distance in the width direction which is the thickness direction, and the second operating screen members 62 are arranged between the first operating screen members 61. In other words, the first operating screen members 61 and the second operating screen members 62 are arranged alternately side by side in the thickness direction. In this embodiment, the number of the first operating screen members 61 is one more than that of the second operating screen members 62. However, the number of the first operating screen members 61 and the number of the second operating screen members 62 may be the same. Also, the number of the first operating screen members 61 may be one less than that of the second operating screen members 62. Each of the first operating screen members 61 and the second operating screen members 62 is a long stainless steel member arranged in an inclined manner so as to be located on the downstream side as it goes upward. However, the first operating screen members 61 and the second operating screen members 62 may be made of other metals, resins, etc. as long as they are excellent in corrosion resistance and durability against raw sludge, and they may be made of different materials. The thickness of each of the first operating screen members 61 and the second operating screen members 62 is 2 mm. This thickness is set to be 2 mm or more and 9 mm or less according to the length of the screen member, the characteristics of the impurities to be removed, etc. Also, the interval W in the width direction between the first operating screen members 61 and the second operating screen members 62 is 2 mm. This interval W is a gap connecting the upstream side and the downstream side set from the balance between the flow rate of the raw sludge passing through the raw sludge impurity removal screen device 6 and the size of the device, and is set to be 0.5 mm or more and 25 mm or less according to the characteristics of the impurities to be removed, etc.

[0025] As shown in FIG. 4, the first operating screen member 61 is provided with first spacing holding spacers 612 protruding on both sides in the thickness direction at four positions spaced apart in the longitudinal direction. Note that the number of the first spacing holding spacers 612 provided on the first operating screen member 61 may be set arbitrarily according to, for example, the length in the longitudinal direction of the first operating screen member 61. Further, the second operating screen member 62 is provided with second spacing holding spacers 622 protruding on both sides in the thickness direction at four positions spaced apart in the longitudinal direction. Note that the number of the second spacing holding spacers 622 provided on the second operating screen member 62 may be set arbitrarily according to, for example, the length in the longitudinal direction of the second operating screen member 62. These first spacing holding spacers 612 and second spacing holding spacers 622 correspond to an example of a spacing holding member. The spacing W between the first operating screen member 61 and the second operating screen member 62 is maintained by these first spacing holding spacers 612, second spacing holding spacers 622, and the fixed uppermost part 63. The configurations of the first spacing holding spacers 612, second spacing holding spacers 622, and the fixed uppermost part 63 will be described in detail later. Among the contaminants X (see FIG. 2) contained in the raw sludge, the contaminants X that cannot pass through the spacing W are captured by the screen body 60 so as to block the spacing W on the upstream side of the screen body 60. In FIG. 3, for simplicity of the drawing, a part of the first operating screen member 61, a plurality of second operating screen members 62, and the fixed uppermost part 63 are omitted. Further, in FIG. 3, the thicknesses of the first operating screen member 61, the plurality of second operating screen members 62, and the fixed uppermost part 63 and the spacing W between the first operating screen member 61 and the second operating screen member 62 are exaggeratedly shown.

[0026] On the upstream side of the first operating screen member 61, a plurality of first stepped portions 611 are provided along the longitudinal direction of the first operating screen member 61. Also, on the upstream side of the second operating screen member 62, a plurality of second stepped portions 621 are provided along the longitudinal direction of the second operating screen member 62. Here, the longitudinal direction of the first operating screen member 61 and the longitudinal direction of the second operating screen member 62 are the transfer directions for transferring contaminants, as will be described later. That is, both the first operating screen member 61 and the second operating screen member 62 are provided with stepped portions (steps) arranged in the transfer direction of the contaminants. Further, near the uppermost part of the first operating screen member 61 and the second operating screen member 62, a fixed uppermost stepped portion 63 is provided. The fixed uppermost stepped portion 63 is located above the water surface of the raw sludge. The fixed uppermost stepped portion 63 has a comb-like shape, and the tooth portion 631 is inserted between the first operating screen member 61 and the second operating screen member 62. Also, the base portion 632 of the fixed uppermost stepped portion 63 is spanned between a pair of side frames 642 and is detachably attached to each of the pair of side frames 642 by screws. This fixed uppermost stepped portion 63 is for scooping up the contaminant X transferred to the uppermost stepped portion relatively from the first operating screen member 61 or the second operating screen member and dropping it into the chute 67.

[0027] As shown in Fig. 3, the base frame 64 has a pair of side frames 642, a pair of bearings 643, a cross plate (not shown), and a pair of side covers (not shown). The pair of side frames 642 extend along the side wall surface 5b of the water tank 5 from the bottom 5a of the water tank 5 to above the upper end of the water tank 5 at both end portions in the width direction of the water tank 5. The side frames 642 are spaced 450 mm apart in the width direction. Note that the interval between the side frames 642 may be set according to the size of the water tank 5, the amount of raw sludge sent to the raw sludge screen unit 2, etc., and any interval may be used. The separation distance in the width direction between the side frames 642 is appropriately determined according to the impurity processing capacity of the raw sludge impurity removal screen device 6 and the amount and quality of the raw sludge flowing into the water tank 5. The bearings 643 are fixed to the respective side frames 642. The cross plate is a plate-like member that extends in the width direction and connects the side frames 642. These bearings 643 and the cross plate are arranged above the water tank 5. The pair of side covers are attached to the respective side frames 642. This side cover is a stainless steel plate material having a rubber seal at the width direction end side. This side cover closes the space between the upstream end portion of the side frame 642 and the side wall surface 5b of the water tank at both end portions in the width direction of the water tank 5. The raw sludge flowing from the upstream side toward the side cover is gathered toward the center side in the width direction by the side cover and flows between the pair of side frames 642.

[0028] The drive mechanism 65 includes a first frame 651, a second frame 652, a drive shaft 653, a motor 654 (see FIG. 2), a gearbox 655, and a shaft coupling 656. The first frame 651 includes a first right frame 651R, a first left frame 651L, and two first operating screen cross members 6511. The first right frame 651R and the first left frame 651L are arranged inside the side wall surface 5b of the water tank 5 in the width direction and outside the pair of side frames 642 in the width direction. As shown in FIG. 4, the first right frame 651R is a plate-shaped member integrally formed with a substantially triangular triangular portion and two arm portions extending downward from the triangular portion. The first left frame 651L has a plane-symmetric shape with the first right frame 651R with the center in the width direction of the water tank 5 as the symmetry plane. Also, as shown in FIG. 3, the two first operating screen cross members 6511 are spanned between the first right frame 651R and the first left frame 651L. Both ends in the width direction of the two first operating screen cross members 6511 are respectively fixed to the arm portion of the first right frame 651R and the arm portion of the first left frame 651L. Therefore, the two first operating screen cross members 6511 connect the first right frame 651R and the first left frame 651L. All the first operating screen members 61 are fixed to the upstream side surface of the two first operating screen cross members 6511 at a distance from each other in the width direction.

[0029] The second frame 652 includes a second right frame 652R, a second left frame 652L, and two horizontal members 6521 for the second operating screen. The second right frame 652R and the second left frame 652L are arranged inside the side wall surface 5b of the water tank 5 in the width direction and outside the first right frame 651R and the first left frame 651L in the width direction. As shown in FIG. 4, the second right frame 652R is a plate-like member integrally formed with a substantially triangular portion and two arm portions extending downward from the triangular portion. The second left frame 652L has a plane-symmetric shape with the second right frame 652R with the center in the width direction of the water tank 5 as the symmetry plane. Also, as shown in FIG. 3, the two horizontal members 6521 for the second operating screen are spanned between the second right frame 652R and the second left frame 652L. Both ends in the width direction of the two horizontal members 6521 for the second operating screen are fixed to the arm portion of the second right frame 652R and the arm portion of the second left frame 652L, respectively. Therefore, the two horizontal members 6521 for the second operating screen connect the second right frame 652R and the second left frame 652L. All the second operating screen members 62 are fixed to the upstream side surface of the two horizontal members 6521 for the second operating screen at intervals in the width direction.

[0030] The drive shaft 653 is a shaft extending in the width direction on the upstream side of the screen body 60. The drive shaft 653 penetrates each of the pair of side frames 642 and is rotatably supported by the pair of bearings 643 on the side frames 642. One end of the drive shaft 653 is connected to a shaft coupling 656. The output shaft 655a of the gearbox 655 is also connected to the shaft coupling 656. The gearbox 655 converts the driving force (rotational force) and the driving direction (rotational direction) generated by the motor 654 (see FIG. 2). The driving force of the motor 654 is transmitted to the drive shaft 653 via the gearbox 655 and the shaft coupling 656 and acts as a force to rotate the drive shaft 653. Note that the motor 654 may be arranged so that the axial direction of the output shaft of the motor 654 coincides with the width direction, and the output shaft of the motor 654 and the drive shaft 653 may be directly connected without using the gearbox 655.

[0031] At both ends of the drive shaft 653, which are outside the pair of side frames 642 in the width direction, a first eccentric cam 6531 and a second eccentric cam 6532 are fixed respectively. The first eccentric cam 6531 is a thick disk-shaped cam having a center at a position eccentric with respect to the drive shaft center 653a, which is the axis of the drive shaft 653. The second eccentric cam 6532 has the same shape as the first eccentric cam 6531. However, the center of the second eccentric cam 6532 is arranged on the opposite side with the drive shaft center 653a interposed therebetween with respect to the center of the first eccentric cam 6531. That is, the first eccentric cam 6531 and the second eccentric cam 6532 are fixed at positions with a 180-degree phase shift with the drive shaft 653 as the rotation center. The drive shaft 653 rotates around its axis receiving the rotational force of the motor 654 shown in FIG. 2. As a result, with the drive shaft 653 as the rotation center, the first eccentric cam 6531 and the second eccentric cam 6532 perform a rotational motion in a posture shifted by 180 degrees when viewed from the width direction.

[0032] The first right frame 651R and the first left frame 651L are rotatably supported by a shaft (not shown) provided on the first eccentric cam 6531. Also, the second right frame 652R and the second left frame 652L are rotatably supported by a shaft (not shown) provided on the second eccentric cam 6532. The shaft provided on the first eccentric cam 6531 and the shaft provided on the second eccentric cam 6532 are each spaced equidistantly from the drive shaft center 653a and are arranged at positions shifted by 180 degrees with the drive shaft 653 as the rotation center. For this reason, when the first eccentric cam 6531 and the second eccentric cam 6532 rotate receiving the rotational force of the motor 654 shown in FIG. 2, the first frame 651 and the second frame 652 move in a circular orbit in a state where the phases are shifted by 180 degrees when viewed from the width direction. Thereby, the first operating screen member 61 and the second operating screen member 62 repeatedly move upward and downward at different timings.

[0033] FIG. 5 is a partially enlarged cross-sectional view showing a cut around the first spacing spacer and the second spacing spacer.

[0034] In FIG. 5, the two members with cross-hatching are the first operating screen member 61, and the member with downward left hatching disposed therebetween is the second operating screen member 62. The first spacing spacer 612 and the second spacing spacer 622 have the same configuration and perform the same function except that the positions where they are attached and the objects to which they are attached are different. In the following description, mainly the configuration and function of the first spacing spacer 612 will be described, and the description of the second spacing spacer 622 will be omitted. The first spacing spacer 612 is a combination of a first male part 612m and a first female part 612f. The first male part 612m has a hemispherical head 612mh, a boss part 612mb protruding from the head 612mh, and a locking part 612ml provided at the protruding end of the boss part 612mb. The boss part 612mb has a protruding length greater than or equal to the thickness of the first operating screen member 61. This boss part 612mb is inserted into a first mounting hole 61h provided in the first operating screen member 61 and penetrates the first operating screen member 61. The first female part 612f is hemispherical and has a locking hole 612fh into which the locking part 612ml of the first male part 612m can enter. The edge defining the locking hole 612fh of the first female part 612f and the locking part 612ml of the first male part 612m elastically deform with respect to each other when the locking part 612ml is inserted into the locking hole 612fh. After the locking part 612ml enters the locking hole 612fh, the locking part 612ml is locked to the edge of the locking hole 612fh, so that the spacing spacer 6212 is fixed to the first operating screen member 61. When the head 612mh of the first spacing spacer 612 contacts the second operating screen member 62, the spacing W between the first operating screen member 61 to which the first spacing spacer 612 is attached and the second operating screen member 62 with which the head 612mh contacts is maintained. Also, when the first female part 612f of the first spacing spacer 612 contacts the second operating screen member 62, the spacing W between the first operating screen member 61 to which the first spacing spacer 612 is attached and the second operating screen member 62 with which the first female part 612f contacts is maintained. Similarly, the spacing W between the first operating screen member 61 and the second operating screen member 62 is also maintained by the second spacing spacer 622.

[0035] Next, the operations of the first operating screen member 61 and the second operating screen member 62 in the raw sludge contaminant removal screen device 6 will be described.

[0036] FIG. 6 is a diagram showing the operations of the first operating screen member and the second operating screen member step by step. This FIG. 6 is a view of the first operating screen member and the second operating screen member as seen from the width direction. In FIG. 6, the first operating screen member 61 is shown using a thin broken line so that the operations of the first operating screen member 61 and the second operating screen member 62 can be clearly understood. Note that in FIG. 6, the left side of the figure is the upstream side and the right side of the figure is the downstream side.

[0037] FIG. 6(a1) shows a state where the first operating screen member 61 and the second operating screen member 62 are in the home position. The control unit 66 (see FIG. 2) stops the motor 654 (see FIG. 2) so that the first operating screen member 61 and the second operating screen member 62 are positioned in the home position. Thereby, when the motor 654 is not driven, the first operating screen member 61 and the second operating screen member 62 wait in this home position. In the home position, except for the lowermost stage of the first operating screen member 61 and the uppermost stage of the second operating screen member 62, the first stage portion 611 of the first operating screen member 61 and the second stage portion 621 of the second operating screen member 62 are in a state of almost overlapping when viewed from the width direction. Also, contaminants X are caught from the 11th stage from the bottom of the first stage portion 611 of the first operating screen member 61 shown in FIG. 6(a1) to the 10th stage from the bottom of the adjacent second operating screen member 62. In many cases, the contaminants X are caught across a plurality of the first stage portions 611 and a plurality of the second stage portions 621 in the width direction. The height positions of the first stage portion 611 at the 11th stage from the bottom of the first operating screen member 61 shown in FIG. 6(a1) and the second stage portion 621 at the 10th stage from the bottom of the second operating screen member 62 are almost the same.

[0038] As described above, when the motor 654 shown in FIG. 2 is driven, the drive shaft 653, the first eccentric cam 6531, and the second eccentric cam 6532 shown in FIG. 3 rotate, and the first frame 651 and the second frame 652 perform a rotational motion. When the first frame 651 and the second frame 652 rotate, the first operating screen member 61 and the second operating screen member 62 move in a circular orbit when viewed from the width direction while maintaining the inclination angle when viewed from the width direction. That is, the first operating screen member 61 and the second operating screen member 62 repeatedly move upward and downward while moving upstream and downstream.

[0039] FIG. 6(a2) shows the state when the drive shaft 653 rotates 45 degrees clockwise in FIG. 6 from the position of FIG. 6(a1). As shown in FIG. 6(a2), the first operating screen member 61 has moved upward on the upstream side with respect to the position of FIG. 6(a1). Together with the first operating screen member 61, the foreign matter X is also placed on the first step portion 611 of the 11th step from the bottom and moves upward on the upstream side. Further, the second operating screen member 62 has moved downward on the downstream side with respect to the position of FIG. 6(a1). That is, in the movement from the position of FIG. 6(a1) to the position of FIG. 6(a2), the drive mechanism 65 moves the second operating screen member 62 downward when moving the first operating screen member 61 upward.

[0040] FIG. 6(a3) shows the state when the drive shaft 653 further rotates 45 degrees clockwise in FIG. 6 from the position of FIG. 6(a2). As shown in FIG. 6(a3), the first operating screen member 61 has moved upward on the downstream side with respect to the position of FIG. 6(a2). And together with the first operating screen member 61, the foreign matter X also moves upward on the downstream side. Further, the second operating screen member 62 has moved downward on the upstream side with respect to the position of FIG. 6(a2). Also in the movement from the position of FIG. 6(a2) to the position of FIG. 6(a3), the drive mechanism 65 moves the second operating screen member 62 downward when moving the first operating screen member 61 upward.

[0041] Figure 6(a4) shows the state when the drive shaft 653 further rotates 45 degrees clockwise in Figure 6 from the position of Figure 6(a3). As shown in Figure 6(a4), the first operating screen member 61 has moved further upward on the downstream side with respect to the position of Figure 6(a3). And together with the first operating screen member 61, the foreign matter X has also moved further upward on the downstream side. Also, the second operating screen member 62 has moved further downward on the upstream side with respect to the position of Figure 6(a3). Also in the movement from the position of Figure 6(a3) to the position of Figure 6(a4), the drive mechanism 65 moves the second operating screen member 62 downward when moving the first operating screen member 61 upward.

[0042] Figure 6(a5) shows the state when the drive shaft 653 further rotates 45 degrees clockwise in Figure 6 from the position of Figure 6(a4). As shown in Figure 6(a5), the first operating screen member 61 has moved downward on the downstream side with respect to the position of Figure 6(a4). And together with the first operating screen member 61, the foreign matter X has also moved downward on the downstream side. Also, the second operating screen member 62 has moved upward on the upstream side with respect to the position of Figure 6(a4). At this position of Figure 6(a5), with respect to the position of Figure 6(a1), in the width direction, the first step portion 611 of the first operating screen member 61 and the second step portion 621 of the second operating screen member 62 are exactly in an interchanged arrangement. And the foreign matter X has moved one step upward with respect to the position of Figure 6(a1). In the movement from Figure 6(a4) to Figure 6(a5), the drive mechanism 65 moves the second operating screen member 62 upward when moving the first operating screen member 61 downward.

[0043] Fig. 6(a6) shows the state when the drive shaft 653 further rotates 45 degrees clockwise in Fig. 6 from the position of Fig. 6(a5). As shown in Fig. 6(a6), the first operating screen member 61 has moved further downward on the downstream side with respect to the position of Fig. 6(a5). Also, the second operating screen member 62 has moved upward on the upstream side with respect to the position of Fig. 6(a5). Then, the foreign matter X is transferred from the 11th first-stage portion 611 under the first operating screen member 61 to the 12th second-stage portion 621 under the second operating screen member 62 and moves upward on the upstream side together with the second operating screen member 62. Also in the movement from the position of Fig. 6(a5) to the position of Fig. 6(a6), the drive mechanism 65 moves the second operating screen member 62 upward when moving the first operating screen member 61 downward.

[0044] Fig. 6(a7) shows the state when the drive shaft 653 further rotates 45 degrees clockwise in Fig. 6 from the position of Fig. 6(a6). As shown in Fig. 6(a7), the first operating screen member 61 has moved downward on the upstream side with respect to the position of Fig. 6(a6). Also, the second operating screen member 62 has moved upward on the downstream side with respect to the position of Fig. 6(a6). Then, the foreign matter X moves upward on the downstream side together with the second operating screen member 62. Also in the movement from the position of Fig. 6(a6) to the position of Fig. 6(a7), the drive mechanism 65 moves the second operating screen member 62 upward when moving the first operating screen member 61 downward.

[0045] Fig. 6(a8) shows the state when the drive shaft 653 further rotates 45 degrees clockwise in Fig. 6 from the position of Fig. 6(a7). As shown in Fig. 6(a8), the first operating screen member 61 has moved further downward on the upstream side with respect to the position of Fig. 6(a7). Also, the second operating screen member 62 has moved further upward on the downstream side with respect to the position of Fig. 6(a7). And together with the second operating screen member 62, the foreign matter X has moved upward on the downstream side. Also in the movement from the position of Fig. 6(a7) to the position of Fig. 6(a8), the drive mechanism 65 moves the second operating screen member 62 upward when moving the first operating screen member 61 downward.

[0046] When the drive shaft 653 further rotates 45 degrees clockwise in Fig. 6 from the position of Fig. 6(a8), the first operating screen member 61 moves upward on the upstream side with respect to the position of Fig. 6(a8). Also, the second operating screen member 62 moves downward on the downstream side with respect to the position of Fig. 6(a8). And together with the second operating screen member 62, the foreign matter X moves downward on the downstream side. Thereby, the first operating screen member 61 and the second operating screen member 62 return to the home position shown in Fig. 6(a1). And the foreign matter X is lifted two steps in the first step portion 611 and the second step portion 621 from the position before the start of rotation of the drive mechanism 65 as shown by the two-dot chain line in Fig. 6(a1). In the movement from the position of Fig. 6(a8) to the position of Fig. 6(a1), the drive mechanism 65 moves the second operating screen member 62 downward when moving the first operating screen member 61 upward.

[0047] One cycle of driving of the screen body 60 from the position of Fig. 6(a1) before the rotation of the drive shaft 653 until the drive shaft 653 rotates one turn and returns to the position of Fig. 6(a1) is repeatedly performed, for example, at a speed of about 13 cycles per minute, during a predetermined operation period according to the number of steps of the first operating screen member 61 and the second operating screen member 62.

[0048] As described above, during the operation period, the impurities X supplemented to the screen body 60 are transferred two steps upward every cycle on the upstream side of the screen body 60, and finally slide down from the uppermost stage portion 63 shown in FIG. 4 toward the chute 67 and are discharged outside the impurity removal screen device 6 for raw sludge.

[0049] According to this embodiment, a plurality of first operating screen members 61 and second operating screen members 62 are arranged alternately in the thickness direction. Since the first operating screen member 61 and the second operating screen member 62 are moved upward and downward at different timings respectively, the foreign matter X can be moved two steps upward in one cycle. That is, compared with the conventional foreign matter removal screen device combining a fixed screen member and an operating screen member, the foreign matter X can be efficiently transferred at twice the speed. As a result, the operating period of the motor 654 can be shortened, enabling power saving of the foreign matter removal screen device 6 for raw sludge. Also, even if the total number of the first operating screen member 61 and the second operating screen member 62 is, for example, reduced to half of the total number of the fixed screen member and the operating screen member of the conventional foreign matter removal screen device, the same transfer capacity as the conventional one can be obtained. Thus, the width direction of the portion where the screen body 60 is arranged can be narrowed, and the foreign matter removal screen device 6 for raw sludge can be miniaturized. As a result, the water tank 5 can also be made smaller, enabling miniaturization of the screen unit 2 for raw sludge. Further, since the first operating screen member 61 and the second operating screen member 62 are moved upward and downward at different timings using a common motor 654, when one of the first operating screen member 61 and the second operating screen member 62 moves upward and the other moves downward, the loads due to the weights of the first operating screen member 61 and the second operating screen member 62 cancel each other out, reducing the load on the motor 654. This also enables power saving of the foreign matter removal screen device 6 for raw sludge. Also, since the load in the driving of the drive mechanism 65 is reduced, the durability of the drive mechanism 65 is enhanced. Further, since the fluctuation of the load due to the weights of the first operating screen member 61 and the second operating screen member 62 in one cycle is reduced, the rotational operation becomes smooth, suppressing the vibration of the foreign matter removal screen device 6 for raw sludge. Moreover, in this embodiment, the drive mechanism 65 moves the second operating screen member 62 downward when moving the first operating screen member 61 upward, and moves the first operating screen member 61 downward when moving the second operating screen member 62 upward.Therefore, the weight of the first operating screen member 61 and the weight of the second operating screen member 62 can be almost completely offset, and the load in the driving of the drive mechanism 65 is further reduced. In other words, when one of the first operating screen member 61 and the second operating screen member 62 moves upward, the weight of the other acts as a force to assist the driving of the drive mechanism 65, so that the load in the driving of the drive mechanism 65 can be greatly reduced. As a result, the raw sludge contaminant removal screen device 6 can be driven with less power. In addition, since the balance of the loads on the drive mechanism 65 due to the weights of the first operating screen member 61 and the second operating screen member 62 becomes almost uniform, the rotational movement by the drive mechanism 65 becomes smoother, and the vibration due to the driving is further reduced. Furthermore, since the first operating screen member 61 and the second operating screen member 62 are alternately arranged and the conventionally provided fixed screen member is omitted, the raw sludge contaminant removal screen device 6 can be made smaller. In addition, since the distance W between the first operating screen member 61 and the second operating screen member 62 is maintained by the first spacing spacer 612 and the second spacing spacer 622, the distance W between the first operating screen member 61 and the second operating screen member 62 can be maintained at a constant distance. Also, it is possible to reliably prevent the first operating screen member 61 and the second operating screen member 62 from coming into contact with each other.

[0050] The present invention is not limited to the above-described embodiments and can be variously modified within the scope described in the claims. For example, in the above-described embodiment, the foreign matter removal screen device 6 for raw sludge provided in the raw sludge screen unit 2 and the foreign matter removal screen device 7 for scum provided in the scum screen unit 4 were taken as examples for explanation. However, the present invention is not limited to sewage treatment facilities and can also be applied to facilities for treating water such as industrial water and agricultural water. Further, in the above-described embodiment, the foreign matter removal screen device installed in the water tank 5 was taken as an example for explanation. However, the foreign matter removal screen device may be installed in the sewage flowing through the flow path. Furthermore, the drive mechanism 65 was described by taking as an example the case of moving the first operating screen member 61 and the second operating screen member 62 in a circular orbit when viewed in the width direction. However, it may be configured to perform polygonal movement such as rectangular movement or elliptical movement using a link mechanism or the like. Additionally, in the present embodiment, the screen body 60 was composed of two, namely the first operating screen member 61 and the second operating screen member 62. However, it may be composed of three or more operating screen members that move at different timings. In this case, it is preferable to arrange a plurality of sets in the thickness direction, with each set being formed by arranging one by one in the thickness direction the operating screen members that move at different timings. Also, in this case, the timing for moving each operating screen member upward is preferably set so that the driving load of the drive mechanism 65 is uniform within one cycle in consideration of the total weight of the frame that drives the operating screen member and the operating screen member attached to the frame. By doing so, the effect of reducing power consumption and the effect of suppressing vibration can be enhanced. In addition, fixed screen members that are fixed to the base frame 64 and do not move may be arranged between the first operating screen member 61 and the second operating screen member 62, respectively. In this case, the interval between the first operating screen member 61 and the fixed screen member and the interval between the second operating screen member 62 and the fixed screen member are each set to be 0.5 mm or more and 25 mm or less according to the characteristics of the foreign matter to be removed. Furthermore, a gap reducing member that protrudes in the thickness direction and reduces the gap in the thickness direction may be provided at the lowermost end portion of the first operating screen member 61.By doing so, when the screen body 60 is in the home position shown in Fig. 6(a1), it is possible to prevent the foreign matter X from slipping through to the downstream side from the gap in the thickness direction at the lowermost part between the first operating screen members 61. Furthermore, at least one of the first spacing spacers 612 and the second spacing spacers 622 may be omitted.

[0051] Note that even the constituent elements included only in the description of each of the above-described modification examples may be applied to other modification examples.

[0052] The foreign matter removal screen device described above is a foreign matter removal screen device that transfers foreign matter contained in sewage upward. A plurality of first operating screen members that are arranged at a distance in the thickness direction, provided with a plurality of stepped portions in the transfer direction of the foreign matter, and repeatedly move upward and downward. A plurality of second operating screen members that are arranged between the first operating screen members, provided with a plurality of stepped portions in the transfer direction of the foreign matter, and repeatedly move upward and downward. The first operating screen member moves upward and downward at a timing different from that of the second operating screen member. The first operating screen member and the second operating screen member are alternately arranged without disposing a fixed screen member between the first operating screen member and the second operating screen member.

[0053] Also, in a foreign matter removal screen device that transfers foreign matter contained in sewage upward. A plurality of first operating screen members that are arranged at a distance in the thickness direction, provided with a plurality of stepped portions in the transfer direction of the foreign matter, and repeatedly move upward and downward. A plurality of second operating screen members that are arranged between the first operating screen members, provided with a plurality of stepped portions in the transfer direction of the foreign matter, and repeatedly move upward and downward. The first operating screen member may be characterized in that it moves upward and downward at a timing different from that of the second operating screen member.

[0054] According to this foreign matter removal screen device, since each of the first operating screen member and the second operating screen member transfers foreign matter upward, the foreign matter can be transferred efficiently.

[0055] Here, the first operating screen member may move upward when the second operating screen member moves downward, and move downward when the second operating screen member moves upward. Also, each of the first operating screen member and the second operating screen member may move in a circular orbit. Further, when the step portion provided on the first operating screen member is defined as the first step portion and the step portion provided on the second operating screen member is defined as the second step portion, the first operating screen member transfers foreign matter from the first step portion to the second step portion above the first step portion, and the second operating screen member may transfer foreign matter from the second step portion to the first step portion above the second step portion.

[0056] Further, in this foreign matter removal screen device, an aspect may be provided in which a common actuator for moving each of the first operating screen member and the second operating screen member upward and downward is provided.

[0057] According to this aspect, when one of the first operating screen member and the second operating screen member moves upward and the other moves downward, the weight of the first operating screen member and the weight of the second operating screen member are offset, so that the power consumption of this foreign matter removal screen device can be reduced. Also, since there is no need to add an actuator, this foreign matter removal screen device can be configured at low cost.

[0058] Furthermore, in this foreign matter removal screen device, the first operating screen member and the second operating screen member may be alternately arranged.

[0059] By doing so, the fixed screen member can be omitted to miniaturize the foreign matter removal screen device.

[0060] In addition, in this foreign matter removal screen device, a spacing maintaining member for maintaining the spacing between the first operating screen member and the second operating screen member may be provided.

[0061] By the spacing maintaining member, the spacing between the first operating screen member and the second operating screen member can be maintained at a constant spacing. Also, it is possible to reliably prevent the first operating screen member and the second operating screen member from coming into contact with each other.

[0062] Here, the spacing maintaining member may be detachably attached to the first operating screen member or the second operating screen member and may be replaceable. Also, the spacing maintaining member may be made of resin.

Explanation of Reference Numerals

[0063] 6 Foreign matter removal screen device for raw sludge (Foreign matter removal screen device) 61 First operating screen member 62 Second operating screen member 611 First stage portion 621 Second stage portion X Foreign matter

Claims

1. In a contaminant removal screen device that transfers contaminants contained in wastewater upward, A plurality of first movable screen members are arranged at intervals in a thickness direction, have a plurality of steps in a transport direction of impurities, and repeatedly move upward and downward; a plurality of second movable screen members disposed between the first movable screen members, each having a plurality of steps in a direction in which the impurities are transported, and repeatedly moving upward and downward; a drive mechanism having a first frame to which a plurality of the first movable screen members are fixed and a second frame to which a plurality of the second movable screen members are fixed; The impurity removal screen device is characterized in that the driving mechanism moves the first frame and the second frame, thereby moving the first movable screen member and the second movable screen member upward and downward at different times.

2. 2. The impurity removal screen apparatus of claim 1, wherein the drive mechanism includes a common actuator for moving the first movable screen member and the second movable screen member upward and downward, respectively.

3. 3. The impurity removal screen device according to claim 1, wherein the first movable screen member and the second movable screen member are arranged alternately.

Images