JP2011005435A - Scum scraping device and sedimentation tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scum scraping device which realizes a gradual comeback of the posture of a movable part after the passing of the scum pipe position, and a sedimentation tank provided with such a scum scraping device.SOLUTION: The scum scraping device 13 exhausts the scum floating on the liquid surface of the water to be treated in a sedimentation tank into a scum pipe provided along the liquid surface, by scraping it with a skimmer blade. The scum scraping device 13 includes: a supporting frame 51 which supports the skimmer blade 69, and which moves around under the liquid surface of the water to be treated and repeatedly passes the lower part of the scum pipe; and a scraping part 53 which is rotatably supported against the supporting frame 51 on a rotating axis 59, and has the skimmer blade 69 provided at the tip. At the scraping part 53, a floating part 63 which generates buoyancy at the tip side of the scraping part 53 is provided.

Description

  The present invention relates to a scum scraping device for scraping a scum floating on the liquid level of water to be treated in a settling tank to a scum pipe provided along the liquid level by scraping with a skimmer blade, and such a scum scratching device. It is related with a sedimentation tank provided with.

  Conventionally, a scum removing device described in Patent Document 1 below is known as a technique in such a field. This scum removing device is used in a circular sedimentation basin into which wastewater is introduced, and includes a scum pipe extending in the radial direction of the circular sedimentation basin and a skimmer blade extending in the radial direction and arranged. . The skimmer blade is supported so as to be rotatable via an arm with respect to a scraping support shaft that circulates below the liquid surface. Further, the weight of the weight attached to the lower part of the arm brings the arm upright, and the skimmer blade protrudes above the liquid level.

  When the scraping support shaft is driven around in this state, the skimmer blade moves around the liquid surface of the circular sedimentation basin, scrapes the scum floating on the liquid surface and pushes it into the scum pipe. Scum is discharged out of the circular sedimentation basin through the scum pipe. At the time of passing through the scum pipe position, the arm and the skimmer blade rotate backward while being in contact with the scum pipe and pass below the scum pipe. Then, after passing through the scum pipe position, due to the weight of the weight, the arm and the skimmer blade return to the scraping posture in which the skimmer blade protrudes above the liquid surface.

JP 2001-239105 A

  At the time of returning to this scraping posture, if intense movements occur in the movable parts including the skimmer blades and arms, metal fatigue is likely to occur in the movable parts, and the sludge interface formed in the wastewater is again removed. There is also a problem of winding up. In order to suppress the overshoot of the movement of the movable part, for example, a stopper for stopping the movement of the arm may be provided. When such a stopper is provided, metal fatigue may occur in the arm due to the impact of the arm colliding with the stopper. In view of such a problem, after the skimmer blade passes the scum pipe position, it is desired to return the posture of the movable part including the skimmer blade and the arm with a gentle operation.

  Therefore, the present invention provides a scum scraping device that can return the posture of the movable part with a gentle operation after passing the scum pipe position, and a sedimentation tank equipped with such a scum scraping device. Objective.

  The scum scraping device of the present invention is a scum scratching device that discharges scum floating on the liquid level of the water to be treated in the sedimentation tank to a scum pipe provided along the liquid level by scraping with a skimmer blade, A support material that supports the clearance blade, moves around the surface of the water to be treated and repeatedly passes below the scum pipe, and is supported to be rotatable about a predetermined rotation axis with respect to the support material. A scraping portion having a clearance blade provided at the tip, and the scraping portion is provided with a buoyancy generating portion that generates buoyancy on the tip side of the scraping portion.

  Moreover, the settling tank of the present invention includes a treated water storage section for storing treated water, a scum scraping device that scrapes a scum floating on the surface of the treated water with a skimmer blade, and a liquid for treated water. A scum pipe that is provided along the surface and collects the scum scraped by the scum scraping device and discharges the scum to the outside of the treated water storage unit, and the scum scraping device supports the skimmer blade, A support material that orbits below the surface of the water to be treated and repeatedly passes below the scum pipe, and is supported to be rotatable about a predetermined rotation axis with respect to the support material, and provided at the tip. And a scraping portion having a skimmer blade, wherein the scraping portion is provided with a buoyancy generating portion that generates buoyancy on the tip side of the scraping portion.

  In the scum scraping device of the present invention and the scum scraping device provided in the sedimentation tank of the present invention, the scraping portion is supported so as to be rotatable with respect to a support material that repeatedly passes below the scum pipe. A clearance blade is provided at the tip of the end portion. Then, when the support member moves, the scum that floats on the liquid surface is scraped by the skimmer blade while moving the liquid surface, and the scraped scum is discharged to the scum pipe. Thereafter, the tip end side of the scraping portion passes below the scum pipe while contacting the scum pipe.

  At this time, since the scraping portion is supported so as to be rotatable with respect to the support member, the scraping portion rotates backward with respect to the traveling direction and avoids the scum pipe in a tilted position. Further, the skimmer blade also enters under the liquid level and passes below the scum pipe. After passing through the scum pipe position, the scraping portion returns to the scraping posture, and the skimmer blade returns to the liquid level. Here, in the scraping portion, buoyancy is generated on the tip side by the buoyancy generating portion, and this buoyancy contributes to stabilizing the posture (scratching posture) such that the skimmer blade is positioned on the liquid surface. . As described above, since the buoyancy of the buoyancy generating unit is used for posture recovery, the operation of the scraping portion at the time of posture recovery becomes slower than when the weight weight is used for posture recovery.

  The scraping portion includes a distal end side portion including a buoyancy generating portion, a proximal end portion supported by a support member by hinge coupling on the rotation shaft, and a joint that hinges the distal end portion and the proximal end portion. It is good also as having a part.

  According to this configuration, at the time of passing the spam pipe position, the scraping portion can be inclined rearward by the rotation shaft, and further, the tip side portion can be inclined rearward also in the joint portion. Therefore, the operating width of the scraping portion when the skimmer blade enters under the scum pipe can be reduced, and as a result, the operation of the scraping portion at the time of posture recovery is small and gentle.

  The scraping portion may have a weight that generates a moment in a direction in which the scraping portion is rotated with respect to the support material. With such weights, the restoring force of the posture of the scraping portion can be adjusted.

  Further, specifically, the buoyancy generating unit may be a member that is attached to the scraping unit and has a density lower than that of the water to be treated. With such a member, it is possible to generate buoyancy that contributes to returning the posture of the scraping portion.

  According to the scum scraping device and the sedimentation tank of the present invention, the posture of the movable part can be returned by a gentle operation after passing through the scum pipe position.

It is sectional drawing which shows one Embodiment of the sedimentation tank of this invention with which the scum scraping apparatus of this invention is applied. It is a top view of the sedimentation tank of FIG. It is a perspective view which shows the scum scraping apparatus of this invention. It is a side view of the scum scraping apparatus of FIG. (A), (b), (c) is a side view which shows operation | movement with the scum scraping apparatus of FIG. 3, and a scum pipe.

  Hereinafter, preferred embodiments of a scum scraping device and a sedimentation tank according to the present invention will be described in detail with reference to the drawings.

  As shown in FIGS. 1 and 2, the circular sedimentation tank 1 separates the water to be treated W into sludge and supernatant liquid by precipitating the sludge from waste water containing the sludge (the water to be treated W). Is. Therefore, the circular sedimentation tank 1 includes a circular tank (treated water storage part) 3 that stores the treated water W that is input, and a shaft 5 that extends in the vertical direction at the center of the circular tank 3. A drive unit 7 that rotationally drives the shaft 5, a rake 9 that is fixed to the shaft 5 at the bottom of the circular tank 3, and a scum removing device 10 that removes scum floating on the liquid level H of the water W to be treated. I have. The scum removing device 10 includes a scum pipe 11 that takes in the scum and discharges it to the outside of the circular tank 3, and a scum scraping device 13 that scrapes the scum on the liquid level H and guides it to the scum pipe 11. As will be described in detail later, the scum scraping device 13 moves the skimmer blade 69 around the liquid surface H in a fixed direction at a speed of about 1/20 rotation per minute on the liquid surface H, thereby clearing the scum on the liquid surface H. The blade 69 is scraped and pushed into the scum pipe 11.

  The circular tank 3 is a tank for storing the treated water W, and has a circular cross section. An overflow weir 15 is provided on the inner wall upper portion of the circular tank 3 along the inner peripheral surface. Outside the overflow weir 15, the supernatant liquid flowing over the overflow weir 15 is circular. An inflow trough 17 is provided for discharging to the outside of the tank 3. In addition, a sludge pit 19 is provided in the center of the bottom of the circular tank 3 to collect the precipitated sludge and discharge it to the outside of the circular tank 3. In addition, the bottom part of the circular tank 3 is formed in the inverted cone shape which stagnates toward the center so that the settled sludge collects in the sludge pit 19.

  The drive unit 7 rotates the shaft 5 in the direction of arrow α at a speed of about 1/20 rotation per minute, and rotates the rake 9 and the scum scraping device 13 in the direction of arrow α. The rake 9 rotates the bottom of the circular tub 3 to scrape sludge and is held by the shaft 5. Further, on the lower surface side of the rake 9, there is provided a sludge scraping plate 9 a for scraping the sludge precipitated on the bottom of the circular tank 3 and collecting it in the sludge pit 19.

  The scum pipe 11 is formed in a cylindrical shape and extends in the radial direction of the circular tank 3 from a position slightly away from the shaft 5 to the outside of the circular tank 3. The scum pipe 11 is located at the level of the liquid level H, and is held in the circular tank 3 so as to be rotatable around the cylindrical axis. In addition, a plurality of openings 11 a are formed in the upper portion of the scum pipe 11 so as to be opened on the cylindrical side surface at a position higher than the liquid level H. Furthermore, a discharge port 11b for discharging the scum taken from the opening 11a outside the circular tank 3 is formed at the tip of the scum pipe 11.

  When the skimmer blade 69 approaches the scum pipe 11, the scum pipe 11 is inclined about 40 degrees around the cylindrical axis toward the skimmer blade 69, so that the end of the opening 11 a is submerged below the liquid level H. In this state, when the skimmer blade 69 further approaches the scum pipe 11, the scum S scraped by the skimmer blade 69 is pushed into the opening 11a together with the water to be treated W (see FIG. 5A). It passes through the scum pipe 11 and is discharged from the discharge port 11b. Note that the scum S discharged from the discharge port 11b and the water to be treated W are separated, and the water to be treated W is returned to the previous stage.

  Next, the scum scraping device 13 will be described in more detail with reference to FIGS.

  The scum scraping device 13 includes a rod-like support frame (support material) 51 that is coupled to the shaft 5 and extends horizontally below the liquid level H in the substantially radial direction of the circular tank 3. As the shaft 5 rotates, the support frame 51 rotates and moves in one direction below the liquid level H along a horizontal circular path. The support frame 51 repeatedly passes below the scum pipe 11 every rotation. The moving direction of the support frame 51 and the scraping portion 53 is the arrow α direction. Three scraping portions 53 extending upward are arranged and attached to the support frame 51 in the extending direction of the support frame 51.

  Hereinafter, the structure of the scraping portion 53 will be described. In the following description, as shown in FIG. 3 and FIG. 4, xyz coordinates are used with the z axis in the vertical direction, the y axis in the extending direction of the support frame 51, and the x axis in the direction orthogonal to the support frame 51. In some cases, the positional relationship of each part is represented. Further, when the terms “front” and “rear” are used in the description of the positional relationship, they indicate the front and rear with respect to the movement direction α of the support frame 51 and the scraping portion 53. As shown in FIG. 2, the shaft 5 has a square shape in plan view, and the support frame 51 extends on an extension of one side of the square shaft 5 in plan view. Therefore, strictly speaking, the y direction (extending direction of the support frame 51) is slightly shifted from the radial direction of the circular tank 3, and the x direction (direction orthogonal to the extending direction of the support frame 51) is a circular tank. 3 is slightly deviated from the circumferential direction 3 (moving direction of the support frame 51: arrow α direction).

  As shown in FIGS. 3 and 4, the scraping portion 53 includes two L-shaped arms (base end side portions) 55 and 55 attached to the upper surface of the support frame 51, and distal ends of the L-shaped arms 55 and 55. And a blade unit (front end side portion) 57 attached to the. The L-shaped arms 55 and 55 and the blade unit 57 are hinge-coupled by a joint portion 71, and the blade unit 57 is supported so as to be rotatable around the y-axis with respect to the L-shaped arms 55 and 55. . A protrusion 77 protruding rearward is provided on the rear surface of the upper end of the L-shaped arm 55. The projection 77 hits the blade unit 57 rotated rearward at an angle θ and prevents further rotation, and restricts the rearward rotation angle of the blade unit 57.

  The base end of the L-shaped arm 55 is rotatably supported with respect to a rotation shaft 59 provided on the support frame 51 and extending in the y direction. By such hinge coupling, the L-shaped arms 55 and 55 can rotate around the y-axis about the rotation shaft 59. A weight 61 is attached to each arm front portion 55a protruding forward at the lower end of the L-shaped arm 55. The weight 61 generates a moment that rotates the scraping portion 53 forward around the y axis. The support frame 51 is provided with a stopper 52 that protrudes forward below the arm front portion 55a. The stopper 52 regulates the forward rotation angle of the L-shaped arm 55. The stopper 52 has a buffer rubber 52a that abuts against the arm front portion 55a, and buffers the collision between the arm front portion 55a and the stopper 52. By such weight 61 and stopper 52, the forward rotation of the L-shaped arms 55, 55 can be restricted and the posture can be stabilized.

  The blade unit 57 includes a rectangular parallelepiped float portion (buoyancy generating portion) 63, a float holding portion 65 that holds the lower portion of the float portion 63, a steel plate 67 attached to the front surface of the float portion 63, and a rear surface of the float portion 63. The attached skimmer blade 69 is assembled by bolting. The float part 63 is a molded body made of a material having a density lower than that of the water to be treated W, and functions as a buoyancy generator that generates buoyancy at the tip of the scraping part 53. As a material of the float part 63, for example, FFU (Fiber reinforce Foamed Urethane; glass long fiber reinforced plastic foam) is employed.

  The skimmer blade 69 has a plate shape extending in parallel to the yz plane, and the upper portion thereof protrudes above the liquid level H. A roller 75 is attached to the front surface of the steel plate 67. The float holding portion 65 holds the float portion 63 and is supported at the joint portion 71 so as to be rotatable with respect to the L-shaped arms 55 and 55. For example, stainless steel such as SUS304 is used as the material of each part (L-shaped arm 55, float holding part 65, steel plate 67, and skimmer blade 69) other than the float part 63 in the scraping part 53. Further, as the material of the weight 61, for example, a steel material such as SS400 is employed. The width of the skimmer blade 69 in the y direction may be adjusted so that the three skimmer blades 69 in the three scraping portions 53 are arranged without gaps in the y direction. Further, instead of the configuration in which each scraping portion 53 is provided with one skimmer blade 69, one long plate-like skimmer blade extending in the y direction may be shared by the three scraping portions. . In other words, the three gap blades 69 may be integrated in the y direction.

  Based on such a configuration, the scraping portion 53 in the water W to be treated is formed by the moment resulting from the buoyancy of the float portion 63 and the weight of the weight 61, and the restriction of the L-shaped arm 55 by the stopper 52, as shown in FIG. And it stabilizes with the attitude | position shown in FIG. That is, the scraping portion 53 is stabilized in a posture in which the float portion 63 is positioned vertically above the rotation shaft 59 and the skimmer blade 69 stands upright along the vertical surface and the tip protrudes above the liquid surface H. Such a posture is hereinafter referred to as a “scratching posture”. In addition, what is necessary is just to adjust the shape of a steel plate 67, a magnitude | size, an attachment position, a weight, etc. in order to stabilize the scraping part 53 with such a scraping attitude | position.

  Here, it is assumed that the density and volume of the float portion 63 are adjusted so that the scraping posture can be maintained only by the buoyancy of the float portion 63 even if the weight 61 and the stopper 52 are removed. Further, by adding the weight 61 and the stopper 52, the scraping posture can be further stabilized.

  Next, the operation of the scum scraping device 13 including such a scraping portion 53 will be described. In the circular sedimentation tank 1, when the shaft 5 rotates at a constant speed, the support frame 51 and the scraping portion 53 rotate at a constant speed in the direction of arrow α (see FIG. 2). The skimmer blade 69 protruding above the liquid level H scrapes the scum floating on the liquid level H while moving in the arrow α direction along the liquid level H. At this time, the posture of the scraping portion 53 is the above-described scratching posture, and the skimmer blade 69 standing upright on the liquid surface H scrapes the scum S efficiently. At this time, even when the amount of scum scraped by the protrusion 77 provided on the L-shaped arm 55 of the scraping portion 53 is large, it is possible to avoid the blade unit 57 from being excessively inclined rearward.

  As shown in FIG. 5A, when the skimmer blade 69 approaches the position of the scum pipe 11, the scum pipe 11 rotates so that the opening 11a faces the skimmer blade 69 side. Then, as the clearance blade 69 continues to advance, the scum S accumulated in front of the clearance blade 69 is pushed into the opening 11 a of the scum pipe 11.

  Thereafter, when the support frame 51 continues to advance, the roller 75 of the scraping portion 53 comes into contact with the scum pipe 11 as shown in FIG. Along with this, the scraping portion 53 rotates around the rotation shaft 59 and tilts backward. Further, also in the joint portion 71, the blade unit 57 is rotated backward with respect to the L-shaped arm 55 and tilted, and the skimmer blade 69 is submerged below the liquid surface H. As the support frame 51 continues to advance further, the blade unit 57 including the skimmer blade 69 enters under the scum pipe 11 and avoids the scum pipe 11. At this time, since the roller 75 rolls on the outer peripheral surface of the scum pipe 11, the blade unit 57 moves smoothly along the bottom surface of the scum pipe 11. At this time, the presence of the protrusion 77 prevents the blade unit 57 from rotating at an excessive angle.

  In the scraping portion 53 in a posture for avoiding the scum pipe 11 (hereinafter referred to as “avoidance posture”), the blade unit 57 and the L-shaped arm 55 are rotated forward by the buoyancy of the float portion 63 (arrow). (β direction) moment is generated. Further, the weight in the direction in which the L-shaped arm 55 rotates forward (arrow β direction) is generated by the weight of the weight 61. Therefore, these moments become a restoring force to the scraping posture, and after the scraping portion 53 passes below the scum pipe 11, the scraping portion 53 returns to the scratching posture as shown in FIG. To do. When the posture is returned, the arm front portion 55a hits the stopper 52, so that overshoot is suppressed. At this time, the shock of collision between the arm front portion 55a and the stopper 52 is buffered by the buffer rubber 52a. Note that the restoring force of the scraping portion 53 to the scraping posture can be adjusted by adjusting the weight of the weight 61.

  Then, the effect by this scum scraping apparatus 13 is demonstrated. The scum scraping device 13 uses a structure in which the buoyancy of the float portion 63 generates a posture returning moment of the scraping portion 53, so that the posture returning using only the weight of the weight 61 is performed. Thus, the operation of the scraping portion 53 at the time of posture return becomes gentle. Accordingly, it is possible to suppress metal fatigue of the L-shaped arm 55 and the like due to the operation at the time of returning the posture, and it is possible to suppress damage to the scraping portion 53 and the like due to metal fatigue. Moreover, it can also suppress that the sludge interface in the to-be-processed water W is wound up by the attitude | position return operation | movement of the scraping part 53, and it is hard to become the hindrance to sludge precipitation processing. Further, the impact force of the collision between the L-shaped arm 55 and the stopper 52 when returning to the posture can be suppressed, and metal fatigue of the L-shaped arm 55 and the like due to the impact force can be suppressed.

  Further, as the restoring force means for generating the restoring force of the posture of the scraping portion 53, the float portion 63 having a low density is adopted, and therefore, when only the weight is used as the restoring force means (for example, Patent Document 1 described above). Compared to the above, the overall weight of the scraping portion 53 can be reduced. Further, the impact force of the collision between the L-shaped arm 55 and the stopper 52 can be further suppressed by reducing the weight of the entire scraping portion 53.

  Further, since the scraping portion 53 has the joint portion 71, the scraping portion 53 inclines in two stages at the position of the joint portion 71 and the position of the rotation shaft 59 in the avoidance posture. Therefore, the operating width of the scraping portion 53 can be reduced compared to the case of tilting in one step (for example, Patent Document 1 described above). Accordingly, the posture returning operation of the scraping portion 53 can be reduced, and the movement of the scraping portion becomes slow.

  Further, in the scraping portion 53, the density and volume of the float portion 63 are adjusted so that the scraping posture can be maintained only by the buoyancy of the float portion 63, so the weight 61 (and the arm front portion 55a) and the stopper are adjusted. 52 can be omitted. As a result, the weight of the scraping portion 53 can be further reduced. In other words, in the scraping portion 53, the float portion 63 at the tip portion of the scraping portion 53 serves as an inclination restoring force generation source in the rotation shaft 59 and an inclination restoring force generation source in the joint portion 71. become. Therefore, although the scraping portion 53 in the avoidance posture rotates and tilts at two locations, the restoring force generation source of the two tilts can be only the float portion 63.

  The scraping portion 53 may not be able to maintain the scraping posture only by the buoyancy of the float portion 63 if the weight 61 and the stopper 52 are removed. In this case, the scraping portion 53 includes the weight 61 and the stopper 52 so that the scraping posture can be maintained. Also in this case, the weight 61 can be reduced in weight compared to the case where the restoring force to the scraping posture is generated only by the weight of the weight (for example, the above-mentioned Patent Document 1), and the scraping portion 53 can be reduced in weight.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the present invention is applied to a scum scraping device of a type in which the skimmer blade is rotated in a circular sedimentation tank, but the present invention translates the skimmer blade in a square sedimentation tank, for example. It can also be applied to a type of scum scraping device.

  DESCRIPTION OF SYMBOLS 1 ... Circular sedimentation tank, 3 ... Circular tank (treated water storage part), 11 ... Scum pipe, 13 ... Scum scraping apparatus, 51 ... Support frame (support material), 53 ... Scratching part, 55 ... L-shaped arm ( (Base end side portion), 57 ... blade unit (tip end side portion), 59 ... rotating shaft, 63 ... float part (buoyancy generating part), 69 ... clearance blade, 71 ... joint part, H ... liquid level, S ... scum , W ... treated water.

Claims (5)

A scum scraping device for scraping scum floating on the liquid level of the water to be treated in the sedimentation tank to a scum pipe provided along the liquid level by scraping with a skimmer blade,
Supporting the skimmer blade, and a support material that orbits below the surface of the water to be treated and repeatedly passes below the scum pipe;
A scraping portion that is supported to be rotatable about a predetermined rotation axis with respect to the support material, and has a skimmer blade provided at a tip;
The scum scratching device, wherein the scraping portion is provided with a buoyancy generating portion that generates buoyancy on the tip side of the scraping portion. The scraping portion is
A tip side portion including the buoyancy generator;
A proximal end portion supported by the support member by hinge coupling on the pivot shaft;
The scum scraping device according to claim 1, further comprising a joint portion that hinges the distal end portion and the proximal end portion.   The scum scraping device according to claim 1, wherein the scraping portion has a weight that generates a moment in a direction in which the scraping portion is rotated with respect to the support material.   The scum scraping device according to any one of claims 1 to 3, wherein the buoyancy generating unit is a member attached to the scraping unit and having a density lower than that of the water to be treated. A treated water storage section for storing treated water;
A scum scraping device that scrapes the scum floating on the surface of the water to be treated with a skimmer blade;
A scum pipe that is provided along the surface of the water to be treated, collects the scum scraped by the scum scraping device, and discharges the scum to the outside of the water to be treated;
The scum scraping device is
Supporting the skimmer blade, and a support material that orbits below the surface of the water to be treated and repeatedly passes below the scum pipe;
A scraping portion that is supported to be rotatable about a predetermined rotation axis with respect to the support material, and has a skimmer blade provided at a tip;
The sedimentation tank, wherein the scraping portion is provided with a buoyancy generating portion that generates buoyancy on the tip side of the scraping portion.

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