JP2011252477A - Reverse prewhirl double-suction centrifugal pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To define an angle area so that a discharge flow passage and a horizontal flange may not interfere with each other, for an angle from a horizontal flange joint face to a discharge flow passage volute bladal part, in a reverse prewhirl double-suction centrifugal pump.SOLUTION: In a double-suction centrifugal pump 1 of a reverse prewhirl structure connecting vertically divided casings 2 with a horizontal flange 3 for integration, a suction port 4 or a discharge port 5 is provided in each of the vertical casings 2a and 2b, the bladal parts 9a and 9b of two volute flow passages 7a and 7b are provided facing each other at 180 degrees, respectively, one 9a of the bladal parts is connected with the discharge port 5, the other bladal part 9b is connected with a partition plate 6 of the volute flow passages 7a and 7b, and the bladal part 9a provided on the upper casing 2a is set in the range of 90 to 180 degrees.

Description

  The present invention relates to a reverse pre-swirl double suction centrifugal pump applied to, for example, a seawater desalination apparatus, and more particularly to a casing structure that is easy to manufacture and assemble a reverse pre-swivel double suction centrifugal pump.

  As a centrifugal pump, a double head provided at a position where the two tongue ends are opposed to each other by 180 degrees as shown in FIG. A spiral casing structure is known, but if the tongue end interferes with the upper and lower casing mating surfaces, it was virtually impossible to manufacture.

JP-A-6-123298 Japanese Patent No. 3025668

Conventionally, it is known that a reverse pre-swirl double suction centrifugal pump is effective in improving pump efficiency because the theoretical head at the impeller inlet can be used as a pump head to reduce the diameter of the impeller.
However, when adopting a design in which the vertically divided casing is joined by a horizontal flange provided at the casing outer surface joint, the discharge flow path is located above the horizontal flange, so the horizontal flange and the discharge flow path are formed. There is a problem that the partition plate and the tongue end interfere with each other.

If bonding is performed via packing, it is difficult to fix the narrow packing used on the mating surfaces of the upper and lower molds, “partition plate and tongue end”, and expansion and temperature rise of the casing due to internal pressure during operation・ Operating vibration ・ It could be deteriorated by earth and sand flowing in the water and the packing could come off.
In particular, the water flow around the tongue end is more complicated than the central part of the partition plate length, and the thickness of the partition plate around the tongue end is thin. The coupling through the design has a problem in terms of long-term quality maintenance.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to provide a reverse pre-swirl double suction centrifugal pump from the horizontal flange joint surface to the tongue end portion of the volute channel on the discharge channel side. The angle α defines the angle range where the discharge flow path and the horizontal flange do not interfere with each other, and the partition plate that separates the outer and inner passages of the double spiral is thinner around the tongue end, maintaining performance as well as assembly. Since it becomes difficult, it exists in eliminating the junction part through packing around a tongue end part.

In order to solve the above problems, the present invention employs the following means.
A reverse pre-swirl double suction centrifugal pump according to the present invention is a double pre-swivel centrifugal pump having a reverse pre-swivel structure in which upper and lower divided casings are connected and integrated by a horizontal flange. The tongue ends of the two volute channels are provided at positions facing each other by 180 degrees, one tongue end is connected to the discharge port, and the other tongue end is connected to the partition plate of the volute channel. The tongue end portion provided in the upper casing is set to 90 to 180 degrees.

  According to such a reverse pre-swirl double suction centrifugal pump, the upper and lower casings are provided with suction ports or discharge ports, and the tongue ends of the two volute channels are provided at positions opposed to each other by 180 degrees. The tongue end is connected to the discharge port, the other tongue end is connected to the partition plate of the volute channel, and the tongue end provided in the upper casing is set at 90 to 180 degrees. A good pump efficiency can be obtained by using a reverse pre-swivel double suction structure that does not interfere with the discharge flow path and the horizontal flange.

  In the above-described reverse pre-swirl double suction centrifugal pump, the partition plate has a concavo-convex fitting structure at the joint portion between the upper casing and the lower casing, and the partition plate is partitioned without using packing. It is possible to secure the flow path by integrating the plates.

According to the present invention described above, the reverse pre-turn structure is employed in which the tongue end portions of the two volute channels formed in the casing are opposed to each other by 180 degrees, and the tongue end portion provided in the upper casing is The angle is set from 90 degrees to 180 degrees, and one end of the tongue end is connected to the discharge port, and the other end of the tongue end is connected to the partition plate of the volute flow path, so that particularly turbulence occurs. There is no interference between the periphery of the tongue end and the horizontal flange, and the thickness of the partition plate can be combined using packing. Further, when the concave and convex fitting structures are employed on both end faces of the partition plates to be joined, since the joining via the packing is eliminated, it is possible to provide a reverse pre-turning double suction centrifugal pump that does not stop or check the pump operation due to the packing.
In addition, the reverse pre-slewing double suction centrifugal pump adopting such a structure has a short inflow pipe and a discharge pipe, and can be downsized as a whole.
Further, since the tongue end portion is provided at a position facing 180 degrees, the load on the impeller is applied in a well-balanced manner, and there is an effect that the pressure pulsation is reduced because there is no reduction in the rotational shaft.

Although the flow path partition plate interferes with the horizontal flange portion, the partition plate has a thickness compared to the tongue end portion, and thus a packing structure can be employed. Further, since turbulent flow does not occur as compared with the tongue end portion, it is possible to adopt an uneven fitting structure instead of joining the partition plate joining portions of the upper casing and the lower casing via packing.
As described above, since the joint portion of the upper casing and the lower casing of the partition plate has a concave-convex fitting structure, a narrow packing that is easy to come off due to the fact that there is no bolt in the peripheral portion in the width direction of the partition plate is omitted. be able to.

  That is, in the reverse pre-slewing double suction centrifugal pump, the angle from the horizontal flange joint surface to the volute tongue end portion of the discharge flow path is 90 to 180 degrees as an angle range α in which the discharge flow path and the horizontal flange do not interfere with each other. It is specified in the range (90 degrees ≦ α ≦ 180 degrees).

It is a longitudinal cross-sectional view (AA sectional drawing of FIG. 2) which shows one Embodiment of the reverse pre-rotation double suction centrifugal pump which concerns on this invention. It is the figure which looked at the reverse pre-rotation double suction centrifugal pump which concerns on this invention from the discharge outlet side. It is a longitudinal cross-sectional view (AA sectional drawing of FIG. 2) which shows the modification of the reverse pre-swirl double suction centrifugal pump which concerns on this invention. It is a top view of the packing used for the conventional reverse pre-turning double suction centrifugal pump.

Hereinafter, an embodiment of a reverse pre-swirl double suction centrifugal pump according to the present invention will be described with reference to the drawings.
A reverse pre-swirl double suction centrifugal pump (hereinafter referred to as a centrifugal pump) 1 shown in FIG. 1 and FIG. 2 has a reverse pre-swivel double suction structure in which a casing 2 divided into upper and lower parts is connected by a horizontal flange 3 and integrated. It has become.
The casing 2 can be divided into an upper casing 2a and a lower casing 2b. After the upper flange 3a and the lower flange 3b are joined, they are joined together by a large number of bolts and nuts (not shown).

A pair of left and right suction ports 4 of the centrifugal pump 1 are provided in the lower casing 2 b of the casing 2. Further, the discharge port 5 of the centrifugal pump 1 is provided at one location in the upper casing 2 a of the casing 2.
Inside the casing 2, volute channels 7 a and 7 b that are divided into two by a partition plate 6 are formed. The volute channels 7a and 7b are channels for increasing and discharging the fluid introduced from the left and right suction ports 4, and the fluid pressurized by the rotation of the impeller 8 increases the channel cross-sectional area toward the outlet side. At the same time, it flows out from the discharge port 5 through the volute channels 7a and 7b that are divided into two parts vertically so as to have the same cross-sectional area ratio.

In this case, the volute channels 7a and 7b employ a reverse pre-swivel structure that can reduce the diameter of the impeller 8 by using the theoretical head at the inlet of the impeller as the pump head.
The two volute channels 7a and 7b formed in the casing 2 are provided at positions where their tongue ends (volute tongue ends) 9a and 9b face each other by 180 degrees. Since the tongue end portions 9a and 9b in the configuration example shown in FIG. 1 are both arranged on a vertical line passing through the rotation axis center C of the impeller 8, the volute that is on the discharge flow path side from the joint surface of the horizontal flange 3 is provided. The angle α to the tongue end portion 9a of the channels 7a and 7b is 90 degrees (α = 90 degrees).
One tongue end portion 9a is connected to the discharge port 5, and the other tongue end portion 9b is connected to the partition plate 6 forming the volute channels 7a and 7b.

  In other words, the volute channel 7 a located above the discharge port 5 serves as an inlet, and the tongue end portion 9 a connected to the discharge port 5 is located above the rotation axis C and is located below the discharge port 5. The tongue end 9b connected to the partition plate 6 and serving as the entrance to the path 7b is located below the rotation axis C. In this case, the tongue end 9a, the rotation axis C, and the tongue 9b are all included. They are on the same vertical line. In other words, the tongue end portions 9a and 9b of the volute channels 7a and 7b formed in the casing 2 are provided at opposite positions rotated by 180 degrees about the rotation axis center C, so that the angle α Is 90 degrees.

The centrifugal pump 1 having such a configuration employs a reverse pre-swivel structure in which the tongue end portions 9a and 9b of the two volute channels 7a and 7b formed in the casing 2 are provided at positions facing each other by 180 degrees. Therefore, the volute channels 7a and 7b eliminate the interference between the discharge flow path portion reaching the discharge port 5 and the horizontal flange 3, and the pump has high pump efficiency by effectively utilizing the advantages of the reverse pre-turn structure. Further, in the centrifugal pump 1 employing such a structure, the inlet-side inflow pipe that forms the suction port 4 and the outlet-side discharge pipe that forms the discharge port 5 are shortened. Therefore, the entire centrifugal pump 1 is reduced in size. It becomes possible to become.
Further, since the tongue end portions 9a and 9b are provided at positions facing each other by 180 degrees, the load balance to the impeller 8 is made uniform, the rotational shaft is not reduced and the pressure pulsation is reduced.

Further, in the centrifugal pump 1A of the modified example shown in FIG. 3, the two volute channels 7a 'and 7b' formed in the casing 2A are provided at positions where their tongue end portions 9a 'and 9b' face each other by 180 degrees. It has been. In this modification, since the tongue end portions 9a 'and 9b' are both arranged on a horizontal line passing through the rotation axis center C of the impeller 8, the angle α is 180 degrees. In this case, one tongue end portion 9a 'is connected to the discharge port 5, and the other tongue end portion 9b' is connected to the partition plate 6A forming the volute channels 7a 'and 7b'.
In addition, about the structure similar to embodiment mentioned above, the same code | symbol is attached | subjected and the detailed description is abbreviate | omitted.

Also in the centrifugal pump 1A having such a configuration, the reverse prediction in which the tongue end portions 9a 'and 9b' of the two volute channels 7a 'and 7b' formed in the casing 2A are provided at positions facing each other by 180 degrees. Since the swirl structure is used, the volute flow paths 7a 'and 7b' eliminate the interference between the discharge flow path portion reaching the discharge port 5 and the horizontal flange 3, and the pump efficiency is improved by effectively utilizing the advantages of the reverse pre-turn structure. Can be improved. Further, in the centrifugal pump 1A adopting such a structure, the inlet-side inflow pipe forming the suction port 4 and the outlet-side discharge pipe forming the discharge port 5 are shortened. Therefore, the entire centrifugal pump 1A is reduced in size. It becomes possible to become.
Further, since the tongue end portions 9a 'and 9b' are provided at positions facing each other by 180 degrees, the load balance to the impeller 8 is made uniform, the rotational shaft is not reduced and the pressure pulsation is reduced.

  Thus, in order to solve the above-described problem, the centrifugal pump 1 of the present embodiment has a casing 2 having a horizontally divided structure, and the upper casing 2a and the lower casing 2b are provided with the suction port 4 or the discharge port 5, and two The tongue end portions 9a and 9b of the volute channels 7a and 7b divided into two are provided at positions facing each other by 180 degrees. The tongue end 9a of the upper casing 2a is disposed so as not to interfere with the lower flange 3b, which is a mating surface of the lower casing 2b, and is installed so as not to exceed a position of 180 degrees at the maximum. The tongue end portion 9a 'on the horizontal line of the modified example is the limit position.

As a result, the preferable range of the angle α is 90 degrees or more and 180 degrees or less (90 degrees ≦ α ≦ 180 degrees). Furthermore, the other end of the tongue end 9a of the upper casing 2a is connected to the discharge port 5, and the other end of the tongue end portion 9b of the lower casing 2b is connected to the partition plate 6 of the volute channels 7a and 7b. By creating such a structure, it is possible to adopt a double suction structure for reverse pre-turning.
In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary, it can change suitably.

1,1A Reverse pre-swivel double suction centrifugal pump (centrifugal pump)
2, 2A casing 2a, 2a 'Upper casing 2b, 2b' Lower casing 3 Horizontal flange 4 Suction port 5 Discharge port 6, 6A Partition plate 7a, 7a ', 7b, 7b' Volute flow path 8 Impeller 9a, 9a ', 9b, 9b 'tongue end 10 packing

Claims (2)

In a double suction centrifugal pump with a reverse pre-swivel structure in which casings divided into upper and lower parts are connected by a horizontal flange and integrated,
The upper and lower casings are provided with suction ports or discharge ports, and the tongue ends of the two volute channels are provided at positions facing each other by 180 degrees, one tongue end is connected to the discharge port, and the other tongue end The part is connected to the partition plate of the volute channel, and the tongue end portion provided in the upper casing is set at 90 to 180 degrees. 2. The reverse pre-turning double suction centrifugal pump according to claim 1, wherein the partition plate has a concave-convex fitting structure at a joint portion between the upper casing and the lower casing.

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