JP2009092049A - Double suction centrifugal pump and its performance adjustment method - Google Patents

Abstract

The present invention provides a pull-out type pump that can realize a pump that balances axial thrust while facilitating insertion / extraction of an impeller into a casing. At that time, the outer shape of the impeller for adjusting the pump performance can be cut.
A pump is formed by integrally forming both suction casings 1 with a casting and providing both suction impellers 7 provided with impeller rings 4 and 5 above and below an outlet c, a pump shaft 8 and a top cover 10. The impeller 7 is inserted integrally into the casing 1 and the upper and lower diameters D and d of the impeller outlet c are the same, and the impeller outlet c is formed by the upper and lower impeller rings 4 and 5. A difference is provided in the upper and lower sliding part diameters D1 and d1.
[Selection] Figure 1

Description

  The present invention relates to a pull-out type double suction centrifugal pump capable of extracting a rotating part above a casing and a performance adjusting method thereof.

  Conventionally, both suction casings are integrally formed of a casting, an upper and lower casing ring is provided inside the casing, and an impeller (impeller) provided with an upper and lower impeller ring (impeller ring) fitted thereto, a pump shaft, 2. Description of the Related Art A pull-out type vertical shaft double suction type centrifugal pump is known in which a top cover is integrally coupled and an impeller is inserted into the casing.

The casing ring has a diameter larger than the lower stage, and the upper and lower impeller rings are fitted so that the upper part is fitted to the outlet part of the impeller and the lower part is fitted to the inlet part. There was a technique (Patent Document 1) that facilitates the process. On the other hand, there has been a technique (Patent Document 2) that solves the problem of the balance of the axial thrust of the pump being lost by making the casing ring and the impeller ring have the same upper and lower diameter. In this technique, since the impeller ring is fitted by providing flange portions positioned on the cylindrical surface concentric with the pump shaft at the upper and lower portions of the impeller outlet portion, the outer shape of the impeller for adjusting pump performance cannot be cut.
Japanese Utility Model Publication No. 49-36483 Japanese Utility Model Publication No. 53-145201

  The problem to be solved by the present invention is that if a difference is provided in the diameter of the sliding portion in order to facilitate the insertion of the impeller into the casing, a pump in which the axial thrust is balanced cannot be realized, and the pump in which the axial thrust of the impeller is balanced When designed, the impeller cannot be easily inserted into the casing.

  Another object of the present invention is to adjust the performance of a double suction centrifugal pump that balances axial thrust.

  An object of the present invention is to provide a double-suction centrifugal pump that can realize a pump that balances axial thrust while facilitating insertion / extraction of an impeller into a casing. Moreover, it is providing the performance adjustment method of the pump.

  In order to achieve the above object, the double suction type centrifugal pump of the present invention is provided with an impeller ring at both ends of the outlet portion of the double suction type impeller, and the impeller is provided from an opening provided on one side of the pump casing. It is a double-suction type centrifugal pump that is inserted, wherein the diameter of the impeller ring on the opening side is larger than the diameter of the impeller outlet, and the other end side impeller ring diameter is set on the impeller outlet. The diameter of the impeller ring is larger than the diameter of the part, the diameter of the impeller ring on the opening side is made larger than that of the impeller ring on the other end side, and the difference between the diameters of the sliding portions at both ends of the impeller ring is provided by the impeller ring It is characterized by.

  With the above configuration, it is possible to realize a pump that balances axial thrust while facilitating insertion / removal of the impeller into / from the casing.

  In the present invention, it is desirable that the joint surface between the impeller outlet and the impeller ring is in a plane that substantially matches the fluid discharge direction from the impeller. With this configuration, it is possible to increase the outer shape cutting margin of the impeller for adjusting the pump performance, so that the performance adjustment range can be expanded.

  The cross-sectional shape of the impeller ring may be formed in an L shape with a sliding portion located on the cylindrical surface concentric with the pump shaft rising from the outer peripheral portion of the joint with both ends of the impeller outlet. desirable. With this configuration, the mass of the impeller ring can be suppressed, and the joint portion with the impeller and the sliding portion with the casing can be formed widely.

  Further, the performance adjusting method of the double suction type centrifugal pump according to the present invention provides an impeller ring at both ends of the outlet portion of the double suction type impeller, and the impeller is inserted from an opening provided on one side of the pump casing. It is a performance adjustment method of both suction type centrifugal pumps fitted, the impeller ring diameter on the opening side is larger than the diameter of the impeller outlet, and the other end side impeller ring diameter is An impeller outlet diameter adjustment allowance is provided as a size larger than the diameter of the impeller outlet portion, and the diameter of the impeller ring on the opening side is made larger than that of the other end side impeller ring. By cutting both ends of the part, the performance of the double suction type centrifugal pump is adjusted without changing the sliding part diameter of both ends of the impeller ring.

  The pump performance can be adjusted while the axial thrust is balanced by the above method.

  As described above, according to the present invention, it is possible to realize a pump that balances axial thrust while facilitating insertion / extraction of the impeller into / from the casing. Further, by cutting the outer shape of the impeller, the pump performance can be adjusted while keeping the axial thrust balanced.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a pump according to an embodiment of the present invention, FIG. 2 is an enlarged view of an impeller of FIG. 1, and FIG. 3 is a longitudinal sectional view of a state where a rotating portion of FIG.

  This embodiment is a pull-out type vertical shaft double-suction centrifugal pump. In FIG. 1, reference numeral 1 denotes a double-suction casing integrally formed by casting without being divided into a plurality of parts, and a vertical pump shaft (vertical shaft) inside The casing rings 2 and 3 having a large diameter on the cylindrical surface concentric with the upper part 8 are provided above and below, and an impeller 7 having impeller rings (impeller rings) 4 and 5 is inserted into the casing rings 2 and 3. An opening 6 for entering and exiting the rotating part is provided at the upper end (one side surface of the casing 1) so that it can be made.

  Reference numeral 7 denotes an impeller of both suctions, which sucks water symmetrically along the axial direction of the pump shaft 8 from the upper and lower inlet portions a and b, flows radially outwardly inside, and exits from the outer peripheral portion. Let it flow out of part c. The impeller 7 is fitted with the impeller rings 4 and 5 at the upper and lower portions of the outlet portion c, and is not fitted into the upper and lower impeller inlet portions a and b. Suction portions 70 and 71 for improving pump efficiency and suction performance are provided in a and b. In the present embodiment, the suction portions 70 and 71 are provided by fitting the suction rings configured separately from the impeller 7 into the upper and lower impeller inlet portions a and b. It may be formed integrally with b. Further, since the flow disturbance is reduced, there is an effect of reducing erosion.

  Here, as shown in FIG. 2, the upper and lower diameters (outer diameters) D and d of the impeller outlet portion c are the same and no difference is provided, but the impeller outlet portion by the upper and lower impeller rings 4 and 5. It is possible to realize a pump design in which the same difference as the inner diameter difference between the upper and lower casing rings 2 and 3 is provided in the upper and lower sliding part diameters D1 and d1 of c, and the axial thrust due to hydraulic unbalance and rotating body mass is balanced. Then, both suction impellers 7 having the same upper and lower diameters D and d of the impeller outlet c can be easily inserted into and removed from the casing 1 through the upper and lower impeller rings 4 and 5. That is, the upper impeller ring diameter (outer diameter) D2 of the impeller rings 4 and 5 fitted to the upper and lower portions of the impeller outlet c is larger than the upper and lower diameters D and d of the impeller outlet c (D2>). D, d), the lower impeller ring diameter (outer diameter) d2 is less than the upper impeller ring diameter D2 and larger than the upper and lower diameters D, d of the impeller outlet c (d ≦ d2 <D1), and the upper impeller The ring diameter D2 is the upper sliding portion diameter D1 of the impeller outlet c, and the lower impeller ring diameter d2 is the lower sliding portion diameter d1 of the impeller outlet c. In this example, the upper and lower diameters D and d of the impeller outlet c are the same, but the present invention is not limited to this.

  In addition, the impeller rings 4 and 5 are shallowly fitted on the outer surface at the upper and lower portions of the impeller outlet portion c (the outermost peripheral portion of the impeller 7) in a plane perpendicular to the pump shaft 8 or slightly inclined. Impeller ring fitting portions 74 and 75 provided with ring grooves 72 and 73 are provided, and the impeller ring fitting portions facing the casing rings 2 and 3 located on the cylindrical surface concentric with the pump shaft 8 are Although not provided, impeller rings 4 and 5 having a thickness direction coinciding with the axial direction of pump shaft 8 are fitted in ring grooves 72 and 73, and in a plane perpendicular to pump shaft 8, The upper and lower portions and the impeller rings 4 and 5 are joined to each other and end surfaces of the outer peripheral portions of the impeller rings 4 and 5 projecting radially outward from the upper and lower portions of the impeller outlet c (the outer peripheral surfaces of the impeller rings 4 and 5) ) On the inner peripheral surfaces of the upper and lower casing rings 2 and 3. It is sufficient to subtract the outer cutting margin T (shown by the hatching in FIG. 2) of the impeller 7 for adjusting the pump performance by the impeller ring fitting portions 74 and 75 by providing a rear lance. The joining margin S between the upper and lower portions of the impeller exit portion c and the impeller rings 4 and 5 that can ensure a large joining area is taken. Therefore, the upper impeller ring inner diameter D3 and the lower impeller ring inner diameter d3 of the impeller rings 4 and 5 are matched with the inner diameters of the ring grooves 72 and 73.

  Further, the cross-sectional shapes of the upper and lower impeller rings 4 and 5 rise on a right angle from the outer periphery of the joints 40 and 50 with the upper and lower portions of the impeller outlet c, and are on a cylindrical surface concentric with the pump shaft 8. The sliding portions 41 and 51 are formed in an L-shape with the sliding portions 41 and 51 located on the outer peripheral surfaces of the sliding portions 41 and 51 including the outer peripheral surfaces of the joint portions 40 and 50. A sliding gap is provided so as to be opposed to each other. By thus forming the L shape, the area of the sliding portions 41 and 51 with the casing 1 can be increased without greatly increasing the mass of the impeller rings 4 and 5, but the impeller ring 4 and 5 is not limited to the L-shaped section, but may be a rectangular section. Further, the joint surface between the impeller outlet c and the impeller rings 4 and 5 is mainly in a plane perpendicular to the pump shaft 8 in this embodiment, but substantially coincides with the fluid discharge direction from the impeller 7. It suffices if it is within the plane, and it may be a slightly inclined plane.

  In FIG. 1, the pump shaft 8 is attached to the lower portion thereof via an impeller key (not shown) so that the impeller 7 does not idle with respect to the pump shaft 8, and a top cover 10 is attached to the upper portion thereof with a bush 11 and a sealing portion 12. It is fastened integrally through Further, the lower end of the pump shaft 8 is fitted with an underwater bearing 14 and is inserted into and supported by a bearing portion 15 provided in a concave shape at the bottom of the casing 1.

  The upper part of the pump shaft 8 is fitted with bearings 18 and 19 up and down.

  Further, a shaft coupling 24 (only the shaft coupling on the pump shaft 8 side is shown in the figure) is interposed between the pump shaft 8 and an electric motor shaft (not shown) at the upper end of the pump shaft 8 so as to be coupled together coaxially. Is attached to the pump shaft 8 via a shaft coupling key (not shown) so as not to idle. There are various methods such as connecting an electric motor directly, coupling with an electric motor via an intermediate shaft joint, and a reduction gear instead of an electric motor.

  When the pump configured as described above is operated by operating an electric motor (not shown), the impeller 7 rotates in the casing 1, and by the rotation, both suction operations are performed from the suction port A and gradually discharged from the discharge port B. It is. At this time, the impeller rings 4 and 5 are fitted to the upper and lower portions of the impeller outlet portion c, and suction blade rings such as bell mouth-shaped suction portions 70 and 71 are provided at the upper and lower impeller inlet portions a and b. Therefore, the pump efficiency can be improved, the erosion prevention of the impeller 7 and the suction performance can be improved. The durability or downsizing of the bearing 18 or 19 supporting the shaft thrust of the pump can be improved, and the rotation of the rotating part of the pump can be smoothly performed on the bearing 18 or 19 to improve the pump efficiency.

  In addition, the casing 1 is integrally formed of a casting without being divided into a plurality of parts and has a simple structure, so that the manufacturing cost can be suppressed and the assembly / disassembly is facilitated by reducing the number of parts of the pump. .

  To remove the pump rotating portion, the intermediate shaft (not shown) is removed, and the pump shaft 8, the impeller 7 and the top cover 10 are shown in FIG. 3 by lifting the wire rope, chain block and crane (not shown) from the state shown in FIG. In the meantime, it can be pulled out as a unit, and can be mounted as shown in FIG. 1 by hanging from the state shown in FIG. At this time, the lower impeller ring 5 passes through the upper casing ring 2, but the upper and lower diameters D and d of the impeller outlet c are the same, and no difference is provided between the lower and upper impeller rings 4 and 5. Since there is a difference between the upper and lower sliding part diameters D1 and d1 of the car outlet part c, and the lower impeller ring diameter d2 is smaller than the upper impeller ring diameter D2 corresponding to the inner diameter of the upper casing ring, there is a slight misalignment. Even if this occurs, the lower impeller ring 5 does not hit the upper casing ring 2, and the impeller 7 can be easily inserted into and removed from the casing 1.

  Further, the impeller 7 is provided with shallow ring grooves 72 and 73 on the outer surface thereof, which are located in a plane perpendicular to the pump shaft 8 and are fitted with the impeller rings 4 and 5 on the outer surface. Wheel ring fitting portions 74 and 75 are provided, and the upper and lower portions of the impeller outlet portion c and the impeller rings 4 and 5 are joined in a plane perpendicular to the pump shaft 8 and are concentric with the pump shaft 8. An impeller ring fitting portion positioned on the surface and facing the casing rings 2 and 3 is not provided, and the upper and lower portions of the impeller outlet c and the impeller rings 4 and 5 are provided in a cylindrical surface concentric with the pump shaft 8. Therefore, the pump performance adjustment can be performed by cutting the upper and lower diameters D and d of the impeller outlet portion c after cutting the outer peripheral portions of the impeller ring fitting portions 74 and 75. The upper and lower impeller rings 4 and 5 are then impellers by fitting their joints 40 and 50 into ring grooves 72 and 73 on the outer surfaces of the impeller ring fitting parts 74 and 75 after cutting. Although the upper and lower diameters D and d of the impeller outlet portion c are the same and do not provide a difference, the upper and lower portions of the impeller outlet portion c can be attached to the upper and lower portions of the impeller outlet portion c. A difference is given to the sliding portion diameters D1 and d1, and the outer peripheral surfaces of the sliding portions 41 and 51 can be opposed to the inner peripheral surfaces of the casing rings 2 and 3 by providing a sliding gap.

Here, when the outer shape cut of the impeller 7 exceeds 20% of the impeller outlet portion diameters D and d, it is necessary to increase the width of the impeller ring fitting portions 74 and 75. The outer shape cut of the impeller 7 is desirably performed at 0 to 20% in order to reduce the pump efficiency, and more desirably 0 to 15%.
For example,
With a small bore (300-500mm) / low head (20-30m) pump,
D, d = 400-500mm T = 40-50mm (10%)
With a small bore (300-500mm) / high head (30m or more) pump,
D, d = 500 to 800 mm T = 75 to 120 mm (15%)
A pump with large bore (600-1000mm) / low head (20-30m)
D, d = 600 to 900 mm T = 60 to 90 mm (10%)
A pump with a large bore (600-1000mm) / high head (30m or more)
D, d = 900-1200 mm T = 130-180 mm (15%)
Then, desired pump performance adjustment can be performed without causing a decrease in pump efficiency.

  Moreover, it is desirable that the diameter difference (D1-d1) provided between the upper and lower impeller rings 4 and 5 is 5 to 50 mm. If it is less than 5 mm, the lower impeller ring 5 hits the upper casing ring 2 with a slight misalignment, which is not effective. If the diameter exceeds 50 mm, the upper and lower diameters D and d of the impeller outlet c are the same, and there is a risk of affecting the balance of the axial thrust even though no difference is provided.

  And as for the joining margin S of the upper and lower parts of the impeller exit part c and the impeller rings 4 and 5, the remaining joining margin S which subtracted the cutting margin T is 2 to 3 times the cutting margin T. If it is less than 2 times, the joint strength of the impeller rings 4 and 5 is insufficient, and if it exceeds 3 times, it is necessary to increase the width of the impeller ring fitting portions 74 and 75, and the pump efficiency decreases due to the increase in the diameter of the impeller 7 Invite.

  In this embodiment, the rings 2, 3, 4 and 5 are provided on both sides of the casing 1 and the impeller 7, but only the upper and lower impeller rings 4 and 5 may be used. Further, the direction of the rotary shaft in the vertical direction of the pump is not limited to this. Furthermore, although this embodiment shows one embodiment (pull-out form) of the present invention, the present invention is not limited thereto, and various modifications can be made without departing from the spirit of the present invention. is there.

It is a longitudinal cross-sectional view of the pump which concerns on one embodiment of this invention. It is an enlarged view of the impeller of FIG. It is a longitudinal cross-sectional view of the state which extracted the rotation part of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 2, 3 Casing ring 4, 5 Impeller ring 6 Opening part for rotation part in / out 7 Impeller 8 Pump shaft 10 Top cover 11 Bush 12 Sealing part 13 Ground 14 Underwater bearing 15 Bearing part 16, 17 Shaft sleeve 18 , 19 Bearing 20 Lower bearing box 21 Lower bearing cover 22 Upper bearing box 23 Upper bearing cover 24 Shaft joint 40, 50 Joint 41, 51 Sliding part 70, 71 Suction part 72, 73 Ring groove 74, 75 Impeller ring fitting Equipment part a, b Impeller inlet part c Impeller outlet part D, d Upper and lower diameter of impeller outlet part D1, d1 Upper and lower sliding part diameter of impeller outlet part D2, d2 Upper and lower impeller ring diameter S Blade Allowance for joining the upper and lower parts of the car exit and the impeller ring T Cutout allowance for the impeller

Claims (4)

A double suction type centrifugal pump in which an impeller ring is provided at both ends of an outlet portion of a double suction type impeller, and the impeller is inserted from an opening provided on one side of a pump casing,
The impeller ring diameter on the opening side is made larger than the diameter of the impeller outlet part, and the other end side impeller ring diameter is made larger than the diameter of the impeller outlet part,
A double suction type centrifugal pump characterized in that the diameter of the impeller ring on the opening side is made larger than that of the impeller ring on the other end side and a difference is provided in the diameter of sliding portions at both ends of the impeller ring by the impeller ring.   The pump according to claim 1, wherein a joint surface between the impeller outlet portion and the impeller ring is in a plane substantially coinciding with a fluid discharge direction from the impeller.   3. The pump according to claim 2, wherein the impeller ring has a cross-sectional shape formed in an L shape having a sliding portion located on a cylindrical surface concentric with the pump shaft rising from an outer peripheral portion of a joint portion with both ends of the impeller outlet portion. A method for adjusting the performance of a double-suction centrifugal pump, in which an impeller ring is provided at both ends of an outlet of a double-suction impeller, and the impeller is inserted from an opening provided on one side of a pump casing. ,
The diameter of the impeller ring on the opening side is larger than the diameter of the impeller outlet part, and the diameter of the impeller ring on the other end is larger than the diameter of the impeller outlet part. In addition, the diameter of the impeller ring on the opening side is made larger than that of the impeller ring on the other end side, and both ends of the impeller ring are slid by cutting both ends of the impeller outlet. A method for adjusting the performance of a double suction centrifugal pump, wherein the performance of the double suction centrifugal pump is adjusted without changing the diameter.

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