JP4875778B1 - Aeration stirrer - Google Patents

Abstract

In an aeration stirrer in which an axial flow impeller disposed in a draft tube is rotated while supplying air to the draft tube to aerate and stir the liquid to be treated, the treatment to be performed flows from a suction port above the draft tube Reduces the amount of air bubbles already in contact with the liquid and improves aeration and stirring efficiency.
A draft tube 40 provided in a liquid to be processed accommodated in a processing tank TK, an axial impeller 85 provided in the draft tube 40 and rotated by driving of a rotary drive unit 82, and in the draft tube 40 An air supply section 50 for supplying air via an air discharge port 59a, a cover 61 forming a space in which the upper surface and the peripheral surface are closed on the outer periphery of the draft tube 40, one end connected to the space, and the other end And an air discharge path 63 having an opening 61a located near the water surface of the liquid to be treated.
[Selection] Figure 1

Description

  The present invention relates to an aeration stirrer that purifies a liquid to be treated such as sewage and sludge such as sewage, human waste, and factory wastewater.

  2. Description of the Related Art Conventionally, an aeration stirrer is known in which air is blown into a liquid to be processed to dissolve oxygen and the liquid to be processed is fluidly circulated to purify the liquid to be processed aerobically. As described in Patent Documents 1 to 4, such an aeration stirrer generates an agitated water flow by rotating an axial impeller disposed in a cylindrical housing, as well as a diffuser tube and a diffuser. There is a structure in which a structure such as an air plate is installed at the lower part of an axial flow impeller, and air is discharged from a diffuser hole formed in the structure so that air bubbles are mixed into the liquid to be processed.

  Here, FIG. 24 shows an example of a conventional aeration and agitation apparatus. The aeration and agitation device 1 shown in FIG. 24 includes a holding unit 1A, a draft tube 10 that is a cylindrical housing held by the holding unit 1A in the processing tank TK, and a downflow to the liquid to be processed in the draft tube 10 And an air supply unit 1C for supplying air into the draft tube 10.

  The holding unit 1A includes a gantry 7 and a support column 8, and a rectifying plate 9 is disposed on a side surface of a portion of each support column 8 positioned below the water level of the liquid to be treated. The stirring unit 1B includes a motor 2, a drive shaft 5 rotated by the motor 2, and an axial flow impeller 6 attached to the tip of the drive shaft 5. The draft tube 10 is provided with guide vanes 11 arranged coaxially below the axial flow impeller 6.

  The air supply unit 1 </ b> C includes a blower 15, an air supply pipe 14, an air chamber 16, and a diffuser pipe 13, and air from the blower 15 passes through the air supply pipe 14 and the air chamber 16 to form a hollow annular diffuser pipe. 13 and is discharged from the diffuser hole of the diffuser pipe 13 to the lower space of the axial impeller. Then, air is blown into the descending flow formed by the rotation of the axial flow impeller 6 from the air diffuser hole of the air diffuser tube 13 so that the air bubbles are placed on the circulating flow of the liquid to be treated and spread over the entire processing tank. Do.

Japanese Patent No. 3160057 Japanese Patent No. 3649080 Japanese Patent No. 4204020 JP 2002-35784 A

  However, in such an aeration stirrer, as shown in FIG. 24, a part of the air bubbles released into the liquid to be processed and in contact with the liquid to be processed are removed from the downflow of the liquid to be processed, and the draft tube 40 floats along the outer surface of the draft tube and rides on the flow of the liquid to be treated in the vicinity of the upper end of the draft tube and flows again into the draft tube. The buoyancy acting on the inflowed air bubbles causes the direction of circulation of the liquid to be treated. There is a problem in that a force acts in the opposite direction to increase the motor output required to maintain the circulation of the liquid to be treated at a predetermined level. In addition, the amount of air bubbles flowing into the draft tube through such a route increases as the amount of air supplied from the air supply unit increases, and the above problem becomes significant.

  At this time, if the circulation of the liquid to be treated is to be maintained at a predetermined level with a constant motor output, it is necessary to reduce the amount of air supplied from the air supply unit. The problem of not being able to occur.

  In view of the above circumstances, the present invention provides an aeration stirrer that rotates an axial impeller disposed in a draft tube while supplying air into the draft tube to aerate and stir the liquid to be treated. It is an object of the present invention to provide an aeration stirring apparatus capable of reducing the amount of air bubbles already in contact with the liquid to be treated flowing from the mouth and improving the aeration stirring efficiency.

  The aeration stirrer of the present invention includes a draft tube provided in a liquid to be treated contained in a treatment tank, an axial impeller provided in the draft tube and rotated by driving of a rotation drive unit, and air into the draft tube. In the aeration stirrer provided with the air supply unit for supplying air through the discharge port, a cover forming a space in which the upper surface and the peripheral surface are closed on the outer periphery of the draft tube, one end is connected to the space, and the other And an air discharge passage having an opening formed near the water surface of the liquid to be treated.

  In the aeration and agitation apparatus, the draft tube may be held by a support column extending downward from the upper part of the processing tank, and the support column may form an air discharge path.

  Further, the air supply unit has a blower, and an air supply path having a base end connected to the blower and an air discharge unit forming an air discharge port at the tip, and the draft tube is connected to the treatment tank. It may be held by a support column extending downward from the upper portion, and the support column may form an air supply path.

  Further, the draft tube is held by two or more struts extending downward from the upper part of the processing tank, and at least one of the two or more struts forms an air supply path. At least one of the above struts, excluding the struts forming the air supply path, may form the air discharge path.

  Further, the aeration stirrer is a water surface rectifier having a shape in which the diameter of a cross section perpendicular to the direction of the water surface of the liquid to be processed is reduced from the water surface to the axial flow impeller in the vicinity of the water surface of the liquid to be processed above the axial flow impeller. It may be provided. As this water surface rectifier, for example, a conical shape in which the diameter of the cross section is small in the direction from the water surface of the liquid to be treated toward the axial flow impeller, or the diameter of the cross section is small is small. A bell mouth shape that gradually decreases in the direction from the water surface toward the axial impeller can be used. In addition, the cross section of the water surface rectifier may have a shape other than a circle, such as a polygon or an ellipse.

  Also, a holding unit attached to the upper part of the treatment tank, and an agitation unit that has an axial impeller and a water surface rectifier, is inserted into a space formed by the holding unit, and is detachably held by the holding unit. The water surface rectifier may be formed such that the maximum value of the diameter in the direction orthogonal to the insertion direction is smaller than the minimum value of the diameter in the direction orthogonal to the insertion direction of the space. Good.

  According to the aeration and agitation apparatus of the present invention, a draft tube provided in the liquid to be treated contained in the treatment tank, an axial flow impeller provided in the draft tube and rotated by driving of the rotation drive unit, and the draft tube In the aeration stirrer provided with an air supply unit for supplying air via an air discharge port, a cover that forms a space in which the upper surface and the peripheral surface are closed on the outer periphery of the draft tube, and one end thereof are connected to the space If the other end is provided with an air discharge passage in which an opening located near the water surface of the liquid to be treated is formed, air bubbles floating along the outer surface of the draft tube are collected, and the upper part of the draft tube So that the liquid to be treated can be guided and discharged to the vicinity of the water surface so that the liquid to be treated flows into the suction pipe at the top of the draft tube. Reduces the amount of contact already air bubbles, it is possible to improve the aeration stirring efficiency

  Further, in the aeration and agitation apparatus, if the draft tube is held by a support column extending downward from the upper part of the processing tank and the support column forms an air discharge path, the water surface of the liquid to be processed Since there is no need to provide a separate structure for the air exhaust passage that penetrates the vortex, a vortex is generated starting from the structure that penetrates the water surface, and the occurrence of a situation where the operating efficiency of the axial impeller is reduced due to the vortex is suppressed. can do.

  Further, the air supply unit has a blower, and an air supply path having a base end connected to the blower and an air discharge unit forming an air discharge port at the tip, and the draft tube is connected to the treatment tank. If it is held by a column extending downward from the upper part and the column forms an air supply path, it is not necessary to separately provide a structure of an air supply path that penetrates the water surface of the liquid to be treated. Therefore, it is possible to suppress the occurrence of a situation in which a vortex is generated starting from a structure penetrating the water surface and the operating efficiency of the axial impeller is reduced by the vortex.

  Further, the draft tube is held by two or more struts extending downward from the upper part of the processing tank, and at least one of the two or more struts forms an air supply path. In the case where at least one of the above struts excluding the strut forming the air supply path forms an air discharge path, the air supply structure and the air discharge structure penetrating the water surface of the liquid to be treated Since there is no need to provide separate bodies, it is possible to suppress the occurrence of a situation where a vortex is generated starting from a structure penetrating the water surface and the operating efficiency of the axial impeller is reduced by the vortex.

  In addition, the aeration stirrer is a water surface rectifier having a shape in which the diameter of a cross section perpendicular to the direction of the liquid surface of the liquid to be treated is reduced from the water surface to the axial flow impeller in the vicinity of the water surface of the liquid to be treated above the axial flow impeller. In this case, the generation of the air suction vortex can be suppressed, the reduction in the operating efficiency of the axial impeller caused by the air suction vortex can be suppressed, and the suction flow of the liquid to be treated can be reduced. It can be efficiently guided to the axial flow impeller.

  Also, a holding unit attached to the upper part of the treatment tank, and an agitation unit that has an axial impeller and a water surface rectifier, is inserted into a space formed by the holding unit, and is detachably held by the holding unit. When the water surface rectifier is formed such that the maximum value of the diameter in the direction orthogonal to the insertion direction is smaller than the minimum value of the diameter in the direction orthogonal to the insertion direction of the space. The water surface rectifier can be easily passed through the inside of the space when the stirring unit is attached to and detached from the holding unit, and the entire stirring unit can be easily detached from the holding unit. As described above, since the stirring unit is detachably attached to the holding unit, the stirring unit can be easily maintained.

The schematic diagram which shows the state in which the aeration stirring apparatus of this invention was installed in the processing tank Schematic diagram showing how the stirrer is detached from the support structure Schematic diagram showing the structure of the support structure Top view showing the structure of the gantry in the holding part Top view showing the structure of the bearing holder in the holder Partial enlarged view of support structure DD sectional view of the air chamber in FIG. EE sectional view of the air rectification chamber in FIG. Horizontal sectional view of the air discharge part FF cross section of the air discharge part in FIG. Perspective view showing the air discharge part FIG. 11 is a diagram when viewed from the direction of arrow A Schematic diagram showing the configuration of the stirring section GG sectional drawing which shows a mode that the drive shaft was accommodated in the support cylinder in the stirring part of FIG. HH sectional drawing which shows the structure of the 2nd bearing in the stirring part of FIG. II sectional drawing which shows the structure of the water surface rectifier in the stirring part of FIG. Schematic diagram showing how the stirrer is mounted on the support structure Schematic diagram showing the stirrer base installed on the gantry Schematic showing how the second bearing is supported by the bearing holder Sectional drawing which shows a mode that a 2nd bearing is supported by a bearing holding part. The schematic diagram which shows 2nd Embodiment of the aeration stirring apparatus of this invention. BB cross section of the aeration and agitation device of FIG. The schematic diagram which shows 3rd Embodiment of the aeration stirring apparatus of this invention. Schematic diagram showing an example of a conventional aeration stirrer

  Embodiments of the aeration and agitation apparatus of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the aeration and agitation apparatus 100 of the present invention is disposed on the treatment tank TK and agitates and agitates the liquid to be treated accommodated in the treatment tank TK, as shown in FIG. 2. The support structure 20 is provided fixed to the treatment tank TK, and the stirring unit 80 is detachably attached to the support structure 20.

  As shown in FIG. 3, the support structure unit 20 includes a holding unit 30, a draft tube 40, an air supply unit 50, and an air discharge unit 60.

  The holding unit 30 includes a gantry 31, a support member 32, and the like. The gantry 31 is fixed on the treatment tank TK, and has an opening 31a into which the stirring unit 80 is inserted as shown in the top view of FIG. A support member for holding the draft tube 40 is fixed to the gantry 31. The support member includes four support columns 32, and the four support columns 32 are arranged at four corners of a square plane. Of the four columns 32, one column 32 forms part of the air supply unit 50, and the remaining three columns 32 form part of the air discharge unit 60. Details of the air supply unit 50 and the air discharge unit 60 will be described later.

  Further, as shown in FIG. 3, each member 32 includes an upper column 32a and a lower column 32b, and the upper column 32a and the lower column 32b are formed using flange joints or the like above the water level of the liquid to be treated. The internal spaces are connected so as to communicate with each other. Therefore, the upper column 32a is positioned in the atmosphere of the processing tank TK, and the lower column 32b is positioned in the atmosphere and the lower column is positioned in the liquid to be processed. Further, the upper struts 32a are connected by a reinforcing member 32X such as a brace. The reinforcing member 32X increases the rigidity of the entire support member 32 and can improve the vibration damping performance. On the other hand, reinforcement by a brace is not performed on the lower support column 32b so as not to disturb the suction flow around the stagnation mouth at the upper end of the draft tube 40.

  As shown in FIG. 5, a bearing support portion 35 for supporting a second bearing 92 of a stirring portion 80 described later is attached to the upper support column 32 a. The bearing holding portion 35 supports the second bearing 92 in the horizontal direction (arrow XY direction), and is attached below the upper support column 32a. The bearing holder 35 includes an annular frame 35a and a protruding member 35b. The annular frame 35a is formed to have a diameter slightly larger than the diameter of the axial flow impeller 85 so that the axial flow impeller 85 passes through the inside thereof, and is supported by a member 32Y protruding from each column of the upper column 32a. ing. Three to four protruding members 35b are attached to the inner surface of the annular frame 35a toward the center of the ring. As the protruding member 35b goes vertically downward (in the direction of the arrow Z1), an inclination is formed to contact the side surface of the annular member 93 so that the overhang length becomes longer. In addition, since the bearing holding part 35 is attached to the upper support | pillar 32a side which does not immerse, the 2nd bearing 92 inserted and fixed to the bearing holding | maintenance part 35 does not immerse.

  Further, as shown in FIG. 3, a rectifying plate 33 for rectifying the suction flow around the stagnation mouth at the upper end of the draft tube 40 is disposed on the side surface of the lower support column 32b. The rectifying plate 33 extends in the vertical direction (arrow Z direction) and is formed radially toward the diagonal lines of the four support columns 32. The rectifying plate 33 also acts as a flow resistor when the draft tube 40 vibrates on a horizontal plane, and can attenuate the vibration of the column member 32.

  The draft tube 40 forms a downward (arrow Z1 direction) flow in the liquid to be treated, and is held by the support column 32. In addition, the holding | maintenance part 30 mentioned above is positioned in the center of the processing tank TK so that the draft tube 40 may be arrange | positioned in the center of the processing tank TK.

  As shown in FIG. 6, the draft tube 40 has an inflow portion 40a, a processing portion 40b, and an outflow portion 40c, and an axial flow impeller 85 is located in the processing portion 40b. Then, due to the rotation of the axial flow impeller 85, the liquid to be processed flows into the draft tube 40 from the upper end of the inflow portion 40a and is discharged from the lower end of the outflow portion 40c.

  The inflow portion 40a has a bell mouth shape, for example, having a radius of curvature of about 0.5D1 (D1 = axial impeller diameter) toward the upper end and gradually increasing in diameter. Thus, when the liquid to be processed flows into the draft tube 40 from the upper part of the inflow portion 40a, the inlet flow can be reduced and the suction flow can be efficiently guided to the axial impeller 85.

  The processing unit 40b has a substantially constant diameter, and an axial flow impeller 85 is accommodated therein. The clearance between the side wall of the processing unit 40b and the axial impeller 85 is about 0.015D1 (D1: impeller diameter) on one side, and no annular groove for preventing contact is provided on the draft tube 40 side.

  The outflow portion 40c has an upper end connected to the air discharge portion 59. The diameter of the lower end is slightly larger than the diameter of the processing portion 40b so that the diameter of the upper end is slightly larger than the diameter of the processing portion 40b. And so as to be approximately the same size. Thereby, a slit-like cut (air discharge port 59a) extending in the circumferential direction is formed at a position where the outflow part 40c and the processing part 40b are connected, and air is discharged into the draft tube 40 from this cut. The draft tube 40 is arranged so that the distance between the bottom of the processing tank TK and the lower end of the outflow portion 40c is about 2.5D1 to 5D1 (D1: impeller diameter).

  Further, the draft tube 40 has a fixed portion 41 and a plurality of guide vanes 42 in the processing portion 40b. The fixed portion 41 is a hollow body having a bullet-shaped tip, and has a diameter substantially the same as the boss diameter of the axial flow impeller 85. The fixing portion 41 fixes the guide vane 42 in the draft tube 40.

  The plurality of guide vanes 42 are attached in the draft tube 40 at intervals of about 90 ° in the circumferential direction. The guide vane 42 has a length in the flow direction (arrow Z direction) of about 0.4D1 (D1: diameter of the axial flow impeller 85), and a range of about 40% of the upstream length is the axial flow impeller 85. It is inclined in an arc shape in the direction opposite to the inclination of. The arc has a radius of, for example, about 0.14D1 (D1: the diameter of the axial flow impeller 85), and the radius of the arc is formed to be substantially constant with respect to the radial direction of the draft tube 40.

  The draft tube 40 and the agitating unit 80 are positioned so that the gap between the axial flow impeller 85 and the guide vane 42 is, for example, about 0.05D1 (D1: diameter of the impeller 85) at the impeller tip. The smaller these gaps are, the smaller the fluid loss can be reduced. Therefore, it is preferable to make them as small as possible in production and practically.

  The air supply unit 50 supplies air into the draft tube 40, and as shown in FIGS. 3 and 6, the blower 51, the air supply pipes 52 to 54, the air chamber 56, the air rectifying chamber 58, the air A discharge part 59 is provided. Here, the air supply pipes 52 to 54, the air chamber 56, the air rectifying chamber 58, and the air discharge part 59 constitute the air supply path of the present invention.

  The air supply pipe 52 has one end connected to the blower 51 and the other end connected to the air supply pipe 53. The air supply pipe 53 is formed by one support column 32 (an upper support column 32a and a lower support column 32b) having an opening on the upper side surface, and is connected to the air supply tube 52 through the opening and has an opening at the lower end. And is connected to an air supply pipe 54. The air supply pipe 54 has one end connected to the lower end of the air supply pipe 53 and the other end connected to the air chamber 56.

  The air chamber 56 is a hollow annular air chamber provided on the outer periphery of the draft tube 40, and is connected to the air supply pipe 54 through an opening formed in the side wall as shown in FIGS. 6 and 7. In addition, the pressure regulating partition wall 57 (bottom wall) is connected to the air rectifying chamber 58 through small holes 57a formed at substantially equal intervals. Thus, the air flowing in from the air supply pipe 54 can be once filled in the air chamber 56 and then fed into the air rectifying chamber 58, and the pressure of the air flowing into the air rectifying chamber 58 is uniform in the circumferential direction of the draft tube. It can be made. Here, FIG. 7 is a DD sectional view of the air chamber 56 in FIG.

  As shown in FIGS. 6 and 8, the air rectifying chamber 58 is formed with an air rectifying plate 58 a that protrudes from the side wall into the space. The air rectifying chamber 58 regulates the flow of air flowing in from the air chamber 56 and discharges air. It is led to the part 59. Here, FIG. 8 is an EE cross-sectional view of the air rectifying chamber 58 in FIG.

  As shown in FIG. 6, the air discharge part 59 has an upper end connected to the air rectifying chamber 58 and a lower end formed in a slit shape formed at a position where the outflow part 40c of the draft tube 40 and the processing part 40b are connected. It is an air passage connected to a break. The air discharge portion 59 forms a slit-like air discharge port 59 extending continuously in a circumferential shape, and air is discharged into the draft tube 40 from the air discharge port 59a. Here, a horizontal sectional view of the air discharge portion 59 is shown in FIG.

  As described above, if the air discharge port 59a is formed on the inner surface of the draft tube 40 and the structure for supplying air into the draft tube 40 is not provided on the inner side of the draft tube 40, the axial flow Compared to the case where a structure such as an air diffuser is installed in the space directly below the impeller, the flow resistance in the draft tube by the mechanism for supplying air can be reduced, resulting in the same level of aeration and agitation processing. The power required to gain capacity can be reduced.

  Here, the case where the air discharge port 59a is formed so as to be in contact with the inner surface of the draft tube 40 is illustrated, but the air discharge port 59a may be formed directly on the inner surface of the draft tube 40. It may be formed near the inner surface. Here, the air discharge port is formed in the vicinity of the inner surface when it is formed at a position protruding slightly inward from the inner surface of the draft tube 40, and the degree of the protrusion directly contacts the inner surface or the inner surface of the air discharge port. It means that it is small enough to be equated with the case where it is formed. Specifically, when the position of the air discharge port is such that the air discharge portion forming the air discharge port has a portion protruding to the inside of the draft tube 40 from the air discharge port, the most protruding position is the air discharge port. It means that it is within 10% of the inner diameter of the draft tube 40 immediately before (upstream side) where the outlet (or air discharge part) is formed.

  Moreover, the air discharge part 59 has the baffle plate 59b which block | closes the inner half of the air discharge port 59a in the vicinity of the air outlet, as shown in FIGS. The baffle plate 59b is a plate-like body having a large number of irregularities on the peripheral end surface. The baffle plate 59b restricts the flow path width of the air discharge port 59a in the vicinity of the outlet, thereby disturbing the flow of air discharged from the air discharge port 59a. As a result, mixing of the liquid to be processed and bubbles due to turbulent flow is promoted, and oxygen can be efficiently dissolved in the liquid to be processed. Here, FIG. 10 is a horizontal sectional view of a portion where the baffle plate 59b of the air discharge part 59 is formed.

  Here, the case where the baffle plate 59b is a plate-like body having irregularities on the peripheral end surface is illustrated, but the baffle plate 59b is configured to block the air discharge by closing at least a part of the air discharge port 59a. Any device that can exhibit the function of disturbing the flow of air discharged from the outlet 59a is sufficient.

  When air is supplied from the air discharge port 59a into the draft tube 40, an air layer whose thickness increases in the downstream direction is formed on the lower inner surface of the draft tube 40 as shown in FIG. . At the boundary surface S between the air layer and the liquid to be processed, fine air bubbles are generated continuously and over a wide range by the strong shearing force generated by the difference between the jet speed of the air and the downward flow speed by the axial impeller 85. Oxygen can be efficiently dissolved in the treatment liquid.

  In addition, since this air layer restricts the downward flow passage formed by the axial flow impeller to a nozzle shape, the flow velocity of the downward flow is increased from directly below the axial flow impeller 85 to the downstream direction, thereby increasing the shearing force. In addition, it is possible to improve the melting efficiency of oxygen by promoting the refinement of air bubbles. Further, since the thrust force of the axial flow impeller 85 increases as the downward flow speed increases, the pressure in the lower portion of the draft tube 40 increases, and the oxygen dissolution efficiency can be further improved.

  As shown in FIGS. 3, 6 and 11, the air discharge unit 60 includes a cover 61 and an air discharge path 63. The cover 61 forms a space 62 in which the upper surface (excluding a part of the region connected to the air discharge path 63) and the peripheral surface are closed on the outer periphery of the draft tube 40, and the lower surface is opened. The air bubbles floating along the outer surface of the draft tube 40 can be received from the opening and can be temporarily stored in the space 62. The space 62 is connected to the air discharge path 63 via an opening 61 b formed on the upper surface of the cover 61.

  The air discharge path 63 is formed by lower struts 32 b of the remaining three struts 32 except for one strut 32 used as the air supply pipe 53 among the four struts 32. Each lower column 32b has a lower end (one end) attached to the opening 61b and is connected to the upper portion of the space 62 through the opening 61b. As a result, the air bubbles accumulated in the space 62 flow into the air discharge path 63 from the opening 61 b and rise in the air discharge path 63 due to buoyancy. Each lower column 32b has an opening 61a located near the water surface of the liquid to be treated at the upper end (the other end), and air bubbles rising in the lower column 61b are discharged from the opening 61a. .

  12 is a view of FIG. 11 viewed from the direction of arrow A. FIG. As shown in FIG. 12, inside the cover 61, three partition plates 61c that divide the donut-shaped space 62 into three in the circumferential direction are formed, and each of the partition plates 61c divided by these partition plates 61c. The lower columns 32b are connected to the partial spaces one by one. Thereby, the amount of air discharged through the three lower columns 32b can be made substantially the same. As a result, it is possible to avoid the occurrence of vibrations in the support structure portion 20 due to the concentration of the air discharge on some of the lower columns 32b.

  As the amount of air supplied from the air discharge portion 59 increases, the air layer formed in the lower portion of the draft tube 40 becomes thicker, the descending flow velocity near the lower inner surface of the draft tube 40 decreases, and the vicinity of the lower end outer periphery of the draft tube 40 The amount of air bubbles that have flowed out of the descending flow from the reversal and rise along the outer surface of the draft tube 40 increases, but by providing the cover 61 and the air discharge passage 63 as described above, the outer surface of the draft tube Collect air bubbles (air bubbles that have come into contact with the liquid to be treated) along the air and guide them to the vicinity of the water surface of the liquid to be discharged so that they do not flow into the suction port at the top of the draft tube. As a result, the amount of air bubbles already in contact with the liquid to be treated flowing from the suction port at the top of the draft tube is reduced, and a predetermined level of aeration and stirring treatment capacity is obtained. It is possible to reduce the power needed in order.

  Further, by providing the cover 61, the liquid to be treated which has been aerated once in the lower portion of the draft tube 40 and has an increased dissolved oxygen amount rises as it is without spreading into the treatment tank, and flows into the draft tube 40 again. As a result, gas-liquid contact can be promoted preferentially to the liquid to be treated having a low dissolved oxygen content, and the oxygen dissolution efficiency can be improved.

  Further, the water to be treated is pumped up by the rising force of the air bubbles rising in the air discharge path 63, and the water to be treated is pumped up by the so-called air lift effect and discharged from the opening 61a. It is possible to further improve the oxygen dissolution efficiency by allowing the outside air to flow into the surface of the water to be treated from a high position and performing surface aeration.

  As shown in FIG. 13, the stirring unit 80 includes a base 81, a rotation drive unit 82, a drive shaft 84, and an axial flow impeller 85. The base 81 has a substantially rectangular flat surface larger than the opening 31 a of the gantry 31, and the stirring part 80 is held by the holding part 30 by the base 81. The rotation drive unit 82 includes a motor 82a and a speed reducer 82b fixed to the base 81, and the start / stop of rotation and the number of rotations are controlled in the motor 82a and the speed reducer 82b. The drive shaft 84 extends from the rotation drive unit 82 into the processing tank TK and rotates by driving the rotation drive unit 82.

  The axial flow impeller 85 is attached to the tip of the drive shaft 84 and is disposed in the draft tube 40. The axial-flow impeller 85 forms a downward flow (in the direction of arrow Z1) with respect to the liquid to be processed in the draft tube 40 by rotating integrally with the drive shaft 84. The axial flow impeller 85 has a plurality of blades, and the blades are formed with a pitch ratio of 0.9, for example. Here, the pitch means the distance traveled when the spiral surface extended by the axial flow impeller 85 with the geometric blade angle makes one rotation 360 °, and the pitch ratio is obtained by dividing the pitch by the diameter D1 of the impeller. Means. As this axial flow impeller 85, for example, the impeller disclosed in Japanese Patent Nos. 3239170, 3239171, and 3239172 and other known axial flow impellers can be used.

  Further, the stirring unit 80 includes a support cylinder 90, a first bearing 91, a second bearing 92, and a water surface rectifier 97. One end of the support cylinder 90 is fixed to the base 81, and as shown in FIG. 14, the drive shaft 84 passes through and protrudes from the tip of the support cylinder 90. The first bearing 91 is configured to rotatably hold the rotation drive unit 82 side of the drive shaft 94, and is accommodated inside the support cylinder 90 and on the base 81 side. The second bearing 92 is attached to the tip of the support cylinder 90 and holds the middle of the drive shaft 84 rotatably.

  The second bearing 92 is supported in the horizontal direction by the holding unit 30 in the processing tank TK. Specifically, as shown in FIG. 15, the second bearing 92 is housed in an annular member 93 that is fixed to the outside of the tip end of the support tube 90. The annular member 93 has a conical shape whose diameter decreases downward, and an inclined surface is formed on a side surface (see FIG. 13).

  The water surface rectifier 97 is for reducing the free surface of the liquid to be treated in the vicinity of the suction port of the draft tube 40 and reducing the vortex generated on the water surface, and covers the water surface above the axial impeller 85. Is formed. Further, as shown in FIG. 13, it is held by a support member 96 fixed to the annular member 93. By suppressing the generation of vortices in this way, it is possible to suppress a reduction in operating efficiency, vibration, and noise of the axial flow impeller 85. Further, by suppressing the generation of vortices, the distance between the upper end of the draft tube 40 and the maximum water level position of the liquid to be treated in the treatment tank can be made smaller than usual, and the water depth of the air discharge port 59a is made shallower. it can. Thereby, since the required wind pressure of the air blower 15 falls, the required motive power of the air blower 15 can be reduced.

  Further, as shown in FIG. 11, the water surface rectifier 97 has a conical shape whose diameter decreases from the upper part to the lower part. Thereby, when the liquid to be processed flows from the upper part of the draft tube 40, the suction flow can be efficiently guided to the axial flow impeller 85.

  In addition, the axial flow impeller 85 and the water surface rectifier 97 are disposed inside the space in the holding unit 30 when the stirring unit 80 is inserted into the holding unit 30 and attached or removed from the holding unit 30 and pulled out. In order to allow passage, the maximum value of the diameter in the direction orthogonal to the insertion direction (arrow Z direction) is smaller than the minimum value of the diameter in the same direction of the space (in this embodiment, the inner diameter of the bearing holding portion 35). It is formed to be smaller.

  Further, as shown in FIGS. 11 and 16, the water surface rectifier 97 is formed of two divided bodies 97 a and 97 b provided so that the outer peripheral surfaces are continuous with the drive shaft 84 interposed therebetween. The bodies 97a and 97b are configured to be independently removable. Accordingly, the axial flow impeller 85 can be detached from the stirring unit 80 without being detached from the drive shaft 84, and maintenance and inspection can be performed efficiently.

  When the agitating unit 80 is installed in the holding unit 30, it is inserted into the opening 31a of the gantry 31 from above vertically with the axial flow impeller 85 facing downward, and as shown in FIG. The annular member 93 on the stirring unit 80 side is fitted and fixed to the annular frame 35a on the holding unit 30 side. At this time, a wedge action acts on the side surface of the annular member 93 and the inclination of the protruding member 35 b, and the second bearing 92 is firmly fixed to the bearing holding portion 35. Here, FIG. 18 is a schematic diagram showing a state in which the base of the stirring unit is installed on the gantry, and FIGS. 19 and 20 are a horizontal sectional view and a vertical sectional view showing a state in which the second bearing is supported by the bearing holding unit. Respectively. And the base 81 and the mount 31 are fixed using fixing members, such as a volt | bolt.

  Next, with reference to FIG.21 and FIG.22, 2nd Embodiment of the aeration stirring apparatus of this invention is described. FIG. 21 is a schematic view of the aeration and agitation device 200 according to the second embodiment, and FIG. 22 is a cross-sectional view taken along the line BB of FIG. In addition, in the aeration stirring apparatus 200 of FIG. 21, the site | part which has the same structure as the aeration stirring apparatus 100 of FIG. 1 attaches | subjects the same code | symbol, and abbreviate | omits the description. 21 is different from the aeration stirrer 100 in FIG. 1 in the structure of the portion for supplying air into the draft tube 40. FIG.

  As shown in FIGS. 21 and 22, the air supply unit 250 includes a blower 51, air supply pipes 52 to 54, an air chamber 216, and an air diffusion pipe 213. The air chamber 56 is a hollow annular air chamber provided on the outer periphery of the draft tube 40, and is connected to the air supply pipe 54 through an opening formed in the side wall. In addition, an air chamber 56 and a diffuser pipe 213 provided at the lower portion of the axial impeller are connected via four pipe-shaped spokes 214 connecting them. Thereby, the air from the blower 15 is guided to the diffuser pipe 213 via the air supply pipes 52 to 54 and the air chamber 216, and discharged from the diffuser hole 213 a of the diffuser pipe 213 to the lower space of the axial flow impeller 85. It becomes.

  Next, a third embodiment of the aeration and agitation device of the present invention will be described with reference to FIG. FIG. 23 is a schematic diagram of an aeration and agitation device 300 according to the third embodiment. This aeration and agitation apparatus 300 includes the conventional aeration and agitation apparatus 1 shown in FIG. Specifically, as shown in FIG. 23, a cover 61 that forms a space in which the upper surface (excluding a part of the region connected to the column 8) and the peripheral surface are closed on the outer periphery of the draft tube 10 and the lower surface is opened. And the lower end of each support column 8 is connected to the section so that the support column 8 functions as the air discharge path 63, and air discharge is performed at a position near the water surface of the liquid to be treated of each support column 8. The opening 61a is formed.

  According to each said embodiment, it is provided in the draft tube 40; 240; 10 provided in the to-be-processed liquid accommodated in the processing tank TK, and the draft tube 40; 240; 10, and the rotational drive part 82; 82. Axis impeller 85 rotating by driving 1B; 85; 6, and draft tube 40; 240; air supply for supplying air through air discharge ports 59a; 213a; (air diffuser of air diffuser 13); In the aeration stirrer 100; 200; 300 provided with the sections 50; 250; 1C, the cover 61 forms a space in which the upper surface and the peripheral surface are closed on the outer periphery of the draft tube 40; 240; The draft tube 40; 24 is provided with an air discharge passage 63 connected to the other end and formed with an opening located at the other end in the vicinity of the water surface of the liquid to be treated. The air bubbles floating along the outer surface of 0; 10 are collected and guided to the vicinity of the water surface of the liquid to be treated so as not to flow into the suction port of the upper portion of the draft tube 40; 240; 10. Thus, the amount of air bubbles already in contact with the liquid to be treated flowing from the suction port at the top of the draft tubes 40; 240; 10 can be reduced, and the aeration and stirring efficiency can be improved.

  In the above embodiment, the case where the aeration stirrer 100 includes the water surface rectifier 97 is illustrated, but this configuration is not necessarily required and may be installed as necessary.

  Moreover, although the said embodiment illustrated about the case where the support | pillar 32 forms a part of each of an air supply path and an air discharge path, it does not necessarily need to be comprised in this way and it replaces with the support | pillar 32. A pipe for supplying air or discharging air may be separately provided.

TK treatment tank 20 support structure section 30 holding section 31 mount 32 support 35 bearing holding section 40, 240 draft tube 50, 250 air supply section 51 blower 52 air supply pipe 53 air supply pipe 54 air supply pipe 56, 256 air chamber 57 pressure Adjustment partition wall 58 Air rectifying chamber 59a Air discharge port 59b Baffle plate 60 Air discharge part 61 Cover 61a Opening 61c Partition plate 62 Space 63 Air discharge path 80 Stirrer part 82 Rotation drive part 84 Drive shaft 85 Axial flow impeller 90 Support cylinder 91 1st Bearing 92 Second bearing 96 Support member 97 Water surface rectifier 100, 200, 300 Aeration stirrer 213 Aeration tube

Claims (6)

A draft tube provided in the liquid to be treated contained in the treatment tank, an axial flow impeller provided in the draft tube and rotated by driving of the rotation drive unit, and air into the draft tube via an air discharge port In an aeration stirrer provided with an air supply unit for supplying
A cover that forms a space whose upper surface and circumferential surface are closed at a position adjacent to the outer peripheral surface of the draft tube, and one end that is connected to the space and an opening that is positioned near the water surface of the liquid to be treated are formed at the other end. An aeration stirrer characterized by comprising an air discharge passage.   The aeration stirring according to claim 1, wherein the draft tube is held by a support column extending downward from an upper portion of the treatment tank, and the support column forms the air discharge path. apparatus. The air supply unit has a blower, and an air supply path having a base end connected to the blower and an air discharge unit that forms the air discharge port at the tip,
The aeration stirring according to claim 1, wherein the draft tube is held by a support column extending downward from an upper portion of the processing tank, and the support column forms the air supply path. apparatus.   The draft tube is held by two or more struts extending downward from the upper part of the processing tank, and at least one of the two or more struts forms the air supply path, The aeration stirring apparatus according to claim 3, wherein at least one of the two or more struts excluding the strut forming the air supply path forms the air discharge path.   Near the water surface of the liquid to be treated above the axial flow impeller, a water surface rectifier having a shape in which the diameter of a cross section perpendicular to the direction from the water surface of the liquid to be treated is perpendicular to the direction is reduced. The aeration stirrer according to any one of claims 1 to 4. A holding part attached to the upper part of the treatment tank;
The axial flow impeller and the water surface rectifier, and a stirring portion that is inserted into a space formed by the holding portion and is detachably held by the holding portion;
The aeration stirrer according to claim 5, wherein a maximum value of a diameter of the water surface rectifier in a direction orthogonal to the insertion direction is smaller than a minimum value of the diameter in a direction orthogonal to the insertion direction of the space.

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