JP4875777B1 - Aeration stirrer - Google Patents

Abstract

To reduce the required power in an aeration stirrer that agitates and stirs a liquid to be processed by rotating an axial flow impeller disposed in the draft tube while supplying air into the draft tube.
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 And an air supply unit 50 for supplying air via an air discharge port 59a. The air supply unit 50 has a blower 51 and a base end connected to the blower 51, and forms an air discharge port 59a at the tip. The air discharge path 59 includes an air supply path provided with a discharge portion 59, and the air discharge portion 59 forms an air discharge port 59 a on the inner surface of the draft tube 40 or in the vicinity of the inner surface.
[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 6, such an aeration and agitation apparatus rotates an axial impeller disposed in a cylindrical housing to generate an agitation water flow, as well as a diffuser tube and a diffuser. Install a structure such as an air plate under the axial flow impeller (near the downstream side), and discharge air from the diffuser holes formed in the structure so that air bubbles mix with the liquid to be treated. There is what I did.

  Here, FIG. 36 shows an example of a conventional aeration stirrer. 36, the aeration and agitation apparatus 1 includes a holding unit 1A, a draft tube 10 that is a cylindrical housing held in 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.

  As shown in FIGS. 37 and 38, the air supply unit 1 </ b> C includes a blower 15, an air supply pipe 14, an air chamber 16, and an air diffusion pipe 13. Air from the blower 15 is supplied from the air supply pipe 14 and the air chamber. 16 is guided to the air diffuser 13 through 16 and discharged from the air diffuser 13a of the air diffuser 13 to the lower space of the axial impeller. Then, air is blown into the downflow formed by the rotation of the axial impeller 6 through the air diffuser 13a of the air diffuser 13 so that air bubbles are placed on the circulating flow of the liquid to be treated and spread over the entire treatment tank. I do.

Japanese Patent Publication No. 2-3957 JP-B-1-31438 Japanese Patent No. 3160057 Japanese Patent No. 3649080 Japanese Patent No. 4204020 JP 2002-35784 A

  However, in the above-described conventional aeration and agitation apparatus, the structure such as the air diffuser pipe is provided so as to protrude from the inner wall of the draft tube to the lower part of the axial flow impeller, so that the structure is resistant to the downward flow in the draft tube. Thus, there is a problem that the power (output of the motor 2) necessary for circulating the liquid to be processed increases.

  In addition, foreign substances such as hair often contained in the sewage may get entangled with structures such as the air diffuser to further increase the flow resistance and further increase the necessary power. In addition, when the air diffuser is blocked by a foreign matter entangled with the air diffuser, there is a possibility that the power necessary for supplying the air (the output of the blower 15) also increases.

  In view of the above circumstances, the present invention reduces the required power in an aeration stirrer that agitates and stirs a liquid to be treated by rotating an axial impeller disposed in the draft tube while supplying air into the draft tube. An object of the present invention is to provide an aeration stirrer that can be achieved.

  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 an air supply unit for supplying air through the discharge port, the air supply unit includes a blower, and an air discharge unit having a base end connected to the blower and forming an air discharge port at the tip. And an air discharge portion, wherein the air discharge port is formed at or near the inner surface of the draft tube.

  Here, that the air discharge port is formed on the inner surface means that the air discharge port is formed directly on the inner surface or in contact with the inner surface.

  In addition, the air discharge port is formed in the vicinity of the inner surface when the air discharge port is formed at a position slightly away from the inner surface, and the position is the place where the air discharge port is formed. It means that it is within 10% of the inner diameter of the draft tube immediately before (upstream side) inward.

  The aeration stirrer includes a cover that forms a space in which an upper surface and a circumferential surface are closed on the outer periphery of the draft tube, one end connected to the space, and an opening located near the water surface of the liquid to be treated is formed at the other end. And an air discharge path.

  In the aeration and agitation apparatus, 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 supply path or an air discharge path. Also good.

  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 air discharge port may be a slit-like opening extending continuously or intermittently in the circumferential direction of the draft tube, and the air discharge unit may have a baffle plate that blocks a part of the air discharge port. .

  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 through the air discharge port, the air supply unit is connected to the blower and the base end is connected to the blower, and the air discharge forms an air discharge port at the tip An air supply passage provided with a portion, and the air discharge portion forms an air discharge port on or near the inner surface of the draft tube, that is, supplies air into the draft tube. Therefore, a structure such as an air diffuser is installed in the space directly below the axial impeller. Compared to conventional aeration and agitation equipment, the flow resistance in the draft tube by the mechanism for supplying air can be reduced, and as a result, the power required to obtain the same aeration and agitation processing capacity. Can be reduced.

  Furthermore, compared with the conventional aeration and agitation apparatus described above, foreign matter such as hair is less likely to be entangled, and the occurrence of a situation in which the flow resistance increases due to the attachment of the foreign matter or the air discharge port is blocked is suppressed. it can.

  Further, the aeration stirrer includes 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, an end that is connected to the space, and an opening that is positioned near the water surface of the liquid to be treated at the other end If it has an air discharge path that is formed, the old air that has floated along the outer peripheral surface of the draft tube (air that has already come into contact with the liquid to be treated) will not flow directly into the suction port at the top of the draft tube. The liquid to be treated can be guided and discharged to the vicinity of the water surface, thereby reducing the amount of old air flowing from the suction port at the top of the draft tube and supplying fresh air that can be supplied from the air discharge port. The amount can be maintained at a predetermined level.

  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 treatment tank and the support column forms an air supply path or an air discharge path, Since there is no need to provide a separate air supply or air discharge passage structure that penetrates the water surface of the treatment liquid, a vortex is generated starting from the structure that penetrates the water surface, which reduces the operating efficiency of the axial flow impeller. The occurrence of such a situation can be suppressed.

  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 struts forming the air supply path forms the air discharge path, the air discharge 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, if the air discharge port is a slit-like opening that extends continuously or intermittently in the circumferential direction of the draft tube, and the air discharge unit has a baffle plate that blocks a part of the air discharge port, air The flow of air discharged from the discharge port can be disturbed by the baffle plate, and the mixing of the liquid to be processed and the bubbles by the turbulent flow can be promoted, so that oxygen can be efficiently dissolved in the liquid to be processed.

  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 Schematic diagram 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 view of FIG. 11 viewed from the direction of the arrow X 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 figure which shows the modification of an air discharge part The figure for demonstrating the modification of an air discharge part The figure for demonstrating the modification of an air discharge part The figure for demonstrating the modification of a draft tube The figure for demonstrating the modification of a draft tube The figure which shows the modification of an air discharge port The figure which shows the modification of a baffle plate The figure which shows the modification of a baffle plate The figure which shows the modification of a baffle plate The figure which shows the modification of a baffle plate The figure which shows the modification of a structure of an air chamber and an air rectification room 31 is a horizontal sectional view showing the structure of the air chamber. Sectional drawing which shows 2nd Embodiment of the holding | maintenance part in the aeration stirring apparatus of this invention. FIG. 35 is a top view showing an example of the upper column in FIG. Sectional drawing which shows 2nd Embodiment of the stirring part in the aeration stirring apparatus of this invention. Schematic diagram showing an example of a conventional aeration stirrer Partial enlarged view of FIG. Horizontal sectional view showing the structure of the air diffuser of FIG.

  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 on one side (D1: impeller diameter), and the annular groove for preventing contact on the draft tube 40 side (see FIGS. 36 and 37) Not provided.

  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 agitation 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: impeller diameter) 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 a single support 32 having an opening on the upper side surface, and is connected to the air supply pipe 52 through the opening and is connected to the air supply pipe 54 through the opening at the lower end. ing. 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.

  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.

  As described above, the air discharge part 59 forms the air discharge port 59a on the inner surface of the draft tube 40, that is, the structure for supplying air into the draft tube 40 is located inside the inner surface of the draft tube 40. In comparison with the conventional aeration stirrer in which a structure such as a diffuser pipe is installed in the space immediately below the axial flow impeller, the flow resistance in the draft tube by the mechanism for supplying air is reduced. As a result, it is possible to reduce the power required to obtain the same aeration and stirring capacity.

  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 along the lower inner surface of the draft tube 40 is formed 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 is coupled to a cover 61 that forms a space 62 whose upper surface and peripheral surface are closed at the outer peripheral center of the draft tube 40, An air discharge path 63 having an opening 61a located near the water surface of the liquid to be treated is provided at the other end.

  The air discharge path 63 is formed by lower struts 32 b of the remaining three struts 32 except for the one strut 32 used as the air supply pipe 53 among the four struts 32. These lower support columns 32 b are attached at lower ends to the openings 61 b on the upper surface of the cover 61 and connected to the space 62. Further, an opening 61a is provided at a position near the water surface of the liquid to be treated on the upper side surface.

  Here, FIG. 12 shows a view of FIG. 11 viewed from the direction of the arrow X. As shown in FIG. 12, a partition plate 61c that divides the space 62 into three is formed inside the cover, and one lower column 32b is connected to each space divided by the partition plate 61c. Thereby, the quantity of the air discharged via each lower column 32b can be made substantially the same.

  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 floated along the outer surface of the draft tube 40 increases, but the upper surface and the peripheral surface of the outer periphery of the draft tube 40 are thus closed. And an air discharge passage 63 having one end connected to the space and an opening located near the water surface of the liquid to be treated at the other end, along the outer peripheral surface of the draft tube. Guide and discharge near the water surface of the liquid to be treated so that old air that has floated (contacted with the liquid to be treated) does not flow directly into the suction port at the top of the draft tube. It can, thereby, reduces the amount of stale air that flows from the suction port of the upper draft tube, it is possible to maintain the supply of fresh air that can be supplied from the air discharge port at a predetermined level.

  In addition, 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 the amount of dissolved oxygen has increased is short-passed from the lower end of the draft tube 40 and flows again from the suction port at the upper portion of the draft tube 40. Thus, re-aeration can be suppressed, and as a result, the gas-liquid contact is promoted preferentially to the liquid to be treated having a low dissolved oxygen content, and the oxygen dissolution efficiency can be improved.

  Moreover, since the air bubbles rising up the air discharge path 63 also discharge the treated water in the cover 61 due to the air lift effect, the treated water containing bubbles from the opening draws outside air from a position slightly higher than the water surface. It also serves as surface aeration that flows into the treated water surface while being involved, contributing to improvement in oxygen dissolution efficiency.

  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 penetrates inside 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 FIG. 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. 97b is 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.

  As described above, since the stirring unit 80 is detachably attached to the support structure unit 20, maintenance of the stirring unit 80 can be easily performed. Further, since the drive shaft 84 and the first bearing 91 hold the second bearing 93 with respect to the horizontal direction by the holding portion 30, the rolling of the axial impeller 85 is effectively suppressed and the number of revolutions that can be operated is achieved. Can be increased.

Next, the data (Examples 1 and 2) of the aeration stirrer 100 according to the present invention whose performance was confirmed in the water tank test in fresh water and the data (comparative example) of the conventional aeration stirrer 1 are shown in Table 1 below. . In the water tank test, a 7 m × 7 m × 6 m test water tank (treatment tank TK) was filled with fresh water (liquid to be treated) up to 5.0 m (stir volume: 245 m ³ ), and the axial impeller diameter D1 of each aeration stirrer was rotated The results (power efficiency, etc.) are shown when the number and water flow rate are set as shown in Table 1 below. Here, the oxygen transfer amount is the mass at which oxygen in the bubbles dissolves in the liquid to be treated per unit time, and the power efficiency is the oxygen transfer amount by the required power (the total required shaft power of the axial flow turbine and the blower). Divided.

  In Table 1, in Example 1, the required power is substantially the same (slightly larger) than in the comparative example, and the supply air amount is increased 1.2 times. As a result, the water supply flow rate is about 1. It increased 5 times, oxygen transfer increased 1.3 times, and power efficiency increased about 1.3 times. That is, the axial impeller efficiency can be increased by reducing the fluid loss factor in the draft tube compared to the comparative example, and the aeration operation can be performed by reducing the recirculated air bubbles by providing the air bubble collecting cover. Because the maximum supply air volume that can be supplied was stabilized, even when the supply air volume was increased compared to the comparative example, the water flow rate was higher than that of the comparative example, and high oxygen dissolution was achieved by a strong shearing force. This means that the efficiency can be maintained and the amount of oxygen transfer has increased.

  In Table 1, in Example 2, the required power is substantially the same (slightly smaller) than that of the conventional type, and the supply air amount is reduced by a factor of 0.8. Was about 1.6 times, the oxygen dissolution efficiency was increased 1.3 times, and the amount of oxygen transferred was about the same as the conventional type. That is, the axial impeller efficiency can be increased by reducing the fluid loss factor in the draft tube compared to the comparative example, and the aeration operation can be performed by reducing the recirculated air bubbles by providing the air bubble collecting cover. Since it was possible to stabilize and increase the maximum supply air amount that can be supplied, it means that oxygen could be efficiently dissolved with a smaller amount of air than in the comparative example.

  According to the above embodiment, the draft tube 40 provided in the liquid to be treated contained in the treatment tank TK, the axial flow impeller 85 provided in the draft tube 40 and rotated by driving of the rotation drive unit 82, In the aeration stirrer 100 provided with the air supply unit 50 for supplying air into the draft tube 40 via the air discharge port 59a, the air supply unit 50 is connected to the blower 51 and the base end to the blower 51, An air supply path having an air discharge portion 59 that forms an air discharge port 59a at the tip, and the air discharge portion 59 forms the air discharge port 59a on or near the inner surface of the draft tube 40 That is, the structure for supplying air into the draft tube 40 is located inside the draft tube 40 or near the inner surface. In comparison with the conventional aeration and agitation device 1 in which a structure such as the diffuser pipe 13 is installed in the space immediately below the axial flow impeller 85, the inside of the draft tube 40 with a mechanism for supplying air is provided. The channel resistance can be reduced, and as a result, the power required to obtain the same aeration and stirring capacity can be reduced.

  In the above embodiment, 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 is formed on the inner surface of the draft tube 40 as shown in FIG. It may be formed directly on the surface, or may be formed in the vicinity of 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 that forms 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 This means that it is within 10% of the inner diameter of the draft tube 40 immediately before (upstream side) where the discharge port (or air discharge part) is formed.

  For example, when the air discharge port 59a is formed as shown in FIG. 22, the distance D3 from the inner surface of the draft tube 40 of the portion of the air discharge portion 59 that protrudes most to the inside of the draft tube 40 is This means that it is within 10% of the inner diameter D2 of the draft tube 40 immediately before the place where the air discharge portion 59 is formed. When the air discharge portion 59 is formed as shown in FIG. It means that the distance D3 from the inner surface of the draft tube 40 is within 10% of the inner diameter D2 of the draft tube 40 immediately before the place where the air discharge port 59a is formed.

  Further, the air discharge unit 59 places the air bubbles discharged from the air discharge unit 59 on the flow of the liquid to be processed by the axial flow impeller 85, and does not hinder the flow of the liquid to be processed by the axial flow impeller 85. The draft at the position where the axial flow impeller 85 is located at the position of the most projecting portion inside the draft tube 40 (when the air discharge port 59a is formed on the inner face of the draft tube 40). It is preferable that the inner diameter range of the tube 40 is within a range of, for example, 10% toward the inner side and the outer side. For example, as shown in FIGS. 24 and 25, the axial flow impeller 85 has an inner diameter D5 of the draft tube 40 at a position where the air discharge port 59a is formed on the inner surface of the draft tube 40 and the air discharge port 59a is formed. When making it wide or narrow with respect to the inner diameter D4 of the draft tube 40 at the position, it is preferable to satisfy the condition of 0.8D4 <D5 <1.2D4.

  Moreover, in the said embodiment, although illustrated about the case where the air discharge port 59a is a slit-shaped opening continuously extended in the circumferential direction of the draft tube 40, as shown in FIG. 26, it extends in the circumferential direction. A plurality of slit openings may be formed intermittently.

  Moreover, in the said embodiment, although the case where the baffle plate 59b is a plate-shaped object with which the unevenness | corrugation was provided in the peripheral end surface is illustrated, the baffle plate 59b blocks at least one part of the air discharge port 59a. As long as the function of disturbing the flow of air discharged from the air discharge port 59a can be exhibited, it is sufficient. Specifically, for example, a plate-like body having a flat peripheral end surface provided so as to close the inner half of the air discharge port 59a as shown in FIG. 27 or a round shape as shown in FIG. A plate-like body that covers the entire surface of the air discharge ports 59a in which the hole openings 59c are formed at substantially equal intervals may be used, or lateral slit openings 59d that extend in the circumferential direction as shown in FIG. 29 are formed at approximately equal intervals. A plate-like body that covers the entire surface of the air discharge port 59a may be used, or a plate that covers the entire surface of the air discharge port 59a in which horizontal slit openings 59e extending in the radial direction as shown in FIG. 30 are formed at substantially equal intervals. It may be a body. However, in the case where an uneven surface provided on the peripheral end surface as exemplified in this embodiment is used as the baffle plate 59b, the contact area between the air discharged from the air discharge port 59a and the liquid to be processed. Can be increased.

  Moreover, in the said embodiment, although illustrated about the case where the air chamber 56 and the air rectification | straightening chamber 58 are provided adjacent to the upper and lower sides through the pressure regulation partition wall 57, as shown, for example in FIG.31 and FIG.32. The air chamber 156 is installed at a position slightly separated from the air rectifying chamber 58 in the radial direction, and the air chamber 56 and the air rectifying chamber 58 are connected via four to six pipe-shaped spokes 157 that connect them. It may have.

  Moreover, in the said embodiment, although illustrated about the case where the aeration stirring apparatus 100 is provided with the air discharge part 60 and the water surface rectifier 97, those structures are not necessarily required and are installed as needed. do it.

  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.

  33 and 34 are schematic views showing a second embodiment of the holding unit of the present invention, and the aeration and agitation apparatus 200 will be described with reference to FIGS. 33 and 34. In addition, in the aeration stirring apparatus 200 of FIGS. 33 and 34, parts having the same configuration as the aeration stirring apparatus 100 of FIG. The aeration and agitation apparatus 200 of FIGS. 33 and 34 is different from the aeration and agitation apparatus 100 of FIG. 1 in the shape and structure of the upper support column.

  The upper support column 232a shown in FIGS. 33 and 34 is formed of a cylindrical support column and is flange-bonded to the gantry 31. The upper support column 232a includes a straight pipe portion 232X having a diameter slightly larger than the diameter of the axial flow impeller 85, and a conical portion 232Y that is positioned below and gradually increases in diameter downward. A flange for fixing the lower support column 32b is provided at the lower end of the conical portion 232Y. Reinforcing ribs 232Z are attached to the outer surface of the conical portion 232Y at several locations, and bearing holding portions 35b are provided on the inner surface.

  Thus, by making the upper support column 232a cylindrical, it is possible to reduce the number of parts of the holding unit 30 and facilitate assembly, and to improve manufacturability.

  FIG. 35 is a schematic view showing a second embodiment of the stirring unit of the present invention. The stirring unit 280 will be described with reference to FIG. In FIG. 35, parts having the same configuration as the stirring unit 80 of FIG. 13 in the stirring unit 280 are denoted by the same reference numerals and description thereof is omitted. The stirrer 280 in FIG. 35 is different from the stirrer 80 in FIG. 13 in the structure of the drive shaft.

  35, the drive shaft 284 includes a first shaft member 284a and a second shaft member 284b. The first shaft member 284a and the second shaft member 284b are slightly below the second bearing 92 and have a flange 281. Connected by. Thereby, at the time of maintenance / inspection, after removing the water surface rectifier 97 from the annular member 93, the entire length of the stirring unit 80 can be shortened by removing the second shaft member 284 b from the first shaft member 284 a. That is, when the distance from the upper surface of the processing tank TK to the processing liquid surface is large, the drive shaft 84 becomes very long, and the total length of the stirring unit 80 may exceed 3 m. When the processing tank TK is located indoors at a general ceiling height, the stirring unit 80 may not be able to be pulled up in the vertical direction (arrow Z direction) with a crane or the like during maintenance and inspection. At this time, as shown in FIG. 35, if the second shaft member 284b has a configuration that can be attached to and detached from the first shaft member 284a, the maintenance of the stirring unit 80 can be performed by pulling up to the height of the first shaft member 284a. Therefore, maintenance and inspection can be performed efficiently even with a special treatment tank TK.

TK treatment tank 20 support structure section 30 holding section 31 gantry 32, 282 support 35 bearing holding section 40 draft tube 42 guide blade 50 air supply section 51 blower 52 air supply pipe 53 air supply pipe 54 air supply pipe 56 air chamber 57 pressure adjustment Partition wall 58 Air rectifying chamber 58a Air rectifying plate 59 Air discharge portion 59a Air discharge port 59b Baffle plate 60 Air discharge portion 61 Cover 61c Partition plate 63 Air discharge path 80, 280 Stirring portion 81 Base 82 Rotation drive portion 84, 284 Drive shaft 85 Axial flow impeller 90 Support cylinder 91 First bearing 92 Second bearing 96 Support member 97 Water surface rectifier 100, 200 Aeration stirrer 281 Flange 284a First shaft member 284b Second shaft member

Claims (8)

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
The air supply unit has a blower and an air supply path that is provided outside the draft tube, has a proximal end connected to the blower, and forms the air discharge port at a distal end.
The air discharge port is an opening formed on the inner surface of the draft tube on the downstream side of the position of the axial flow impeller in the draft tube , and is a slit hole or the draft tube continuous in the circumferential direction of the draft tube An aeration stirrer characterized by a plurality of discharge holes formed intermittently in the circumferential direction .   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 an air discharge path in which one end is connected to the space and an opening that is located near the water surface of the liquid to be treated is formed at the other end The aeration stirrer according to claim 1, comprising:   The said draft tube is hold | maintained by the support | pillar extended toward the downward direction from the upper part of the said processing tank, This support | pillar forms the said air supply path, The Claim 1 or 2 characterized by the above-mentioned. Aeration stirrer.   The aeration stirring according to claim 2, 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 discharge 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 stirrer according to claim 2, wherein at least one of the two or more columns excluding the column that forms the air supply path forms the air discharge path. The air outlet is a slit-like opening extending continuously or intermittently in the circumferential direction of the draft tube;
The aeration stirring apparatus according to any one of claims 1 to 5, wherein the air discharge part has a baffle plate that blocks a part of the air discharge port.   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 6. 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 7, wherein the maximum value of the diameter of the water surface rectifier 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.