JPH03294691A - Eddy current canned motor pump - Google Patents

Abstract

PURPOSE:To prevent a cavitation and to reduce a noise by arranging plural pump casings and composing the system that the pressure of a pump in the former phase passes through a communication passage and pressurizes a motor chamber and lower pressure parts of the pump at the second phase and the latter. CONSTITUTION:A pump 10 furnishes pump casings 14a and 14b divided into two equal parts, and a centrifugal type radial open impeller 30 is provided in the former part, and a spiral type impeller 32 is provided in the latter part. And, by providing a bypass hole 25 to degas in the pump casing 14b, the gas passes through a canned motor chamber and flows into the gaseous phase part in a pump suction tank. On the other hand, a circular recess 15a is formed on the contact surface of the casing 14a, while a circular projection 15b is formed on the contact surface of the casing 14b, and both members are fitted and connected tightly to each other.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a vortex flow system that automatically causes debris generated in the suction pipe of a liquefied gas transfer vortex pump to flow into and out of the pump's low pressure section during stoppage and operation. Regarding type pumps.

[Prior Art] A conventional vortex pump is also called a Wesco pump, and is suitable as a pump for transferring a small amount of liquid with low viscosity to a high head, for example.

That is, as shown in Fig. 4, this type of pump has a flow path formed on the outer periphery of the impeller, and a suction port and a discharge port located close to this flow path, and the liquid handled by the pump is supplied through the suction port. The flow path is rotated substantially around the circumference to obtain a high head, which is then pressure-fed from the discharge port to the external pressure.

In addition, as a feature of this type of pump supplement, there is a gap between both sides of the impeller and the casing liner (scroll) in contact with it, and a flow path formed on the outer periphery of the impeller between the suction port and the discharge port. There is a gap between the backflow prevention partition wall and the outer periphery of the impeller, and these gaps cause leakage loss, which greatly affects pump characteristics. For this reason, it is necessary to take care in manufacturing to minimize the gaps between the impellers, but if these gaps are made too small, the wear between them will become severe and the pump characteristics will deteriorate. Therefore, it is necessary to leave a certain amount of the gap. Furthermore, this type of pump not only has a simple structure, but also has higher pump efficiency than centrifugal pumps in a narrow flow rate range, and has the characteristics of being able to obtain a much higher head, and also has a discharge volume. Since the amount of water is small, the diameter of the discharge pipe can be made small and the operating power can be reduced, so its applications are extremely wide.

[Problem to be solved by the invention] However, in a conventional whirlpool pump, when the pump is stopped at night in the summer or winter when there is a large difference in outside temperature and then restarted the next morning, the temperature of the liquid in the pump suction pipe becomes higher than that in the suction tank. The liquid temperature becomes higher than that of the liquid, and the liquefied scum in the suction pipe turns into scum and flows into the pump casing via the pump suction part.

However, the impeller blades of the vortex pump have many small notches formed on the outer periphery of the disc, completely separating each adjacent chamber from the other.

In addition, since the pump suction port is provided on the outer periphery of the impeller, if the suction port is filled with debris when the pump rotates, all the chambers partitioned by the blades will be filled with debris. Pump startup is inhibited.

Furthermore, in vortex pumps, it is common practice to make the gap between the impellers very small to increase the pump head. Therefore, in order to reduce the high noise characteristic of pumps in whirlpool pumps, the problem can be solved by enlarging the above-mentioned gap, or the head of the pump will be reduced.

In addition, since the vortex pump cannot obtain sufficient suction performance using only the main impeller and has pump characteristics similar to a positive displacement pump, it has the disadvantage of overloading during shut-off operation.

Therefore, it is necessary to pay sufficient attention when using this type of pump, especially if the power supply frequency (50/60H2>) is different, it may not be possible to achieve the same pump performance without changing all the specifications of the pump part. It had many difficulties in handling.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a vortex pump having a pump characteristic of low flow rate and high head by installing a plurality of pump casings in series so that the pressure in the previous pump section can be transferred to the motor room or the next stage through a communication passage. By configuring the low-pressure part of the pump section after the stage to be pressurized, it is possible to prevent cavitation in the gap between the impeller and the scroll in the next stage and subsequent stages as well as in the enlarged part of the low-pressure part at the outlet of this gap, thereby reducing noise. An object of the present invention is to provide a whirlpool type canned motor pump that can easily design and manufacture a whirlpool type pump with stable pump characteristics.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, a scroll made of a sliding material is disposed on both sides of a vortex type pump impeller, and a scroll made of a sliding material is disposed on both sides of a vortex type pump impeller, and a In a vortex-type canned motor pump that is composed of a pump section in which a plurality of pump casings are arranged in series to form an annular pump chamber, and a canned motor section, a centrifugal impeller is provided in the pump casing of the first stage, and at least A vortex type impeller is provided in the pump casing, and the pump discharge port of the first stage is communicated with the suction port of the next stage pump section through a passage in the pump casing, and further, the same applies to the pump casings of the next stage and thereafter. A bypass hole is formed in each casing that connects the pump casing of the last stage and communicates with the pump part of the previous stage, and the flow passage outlet of the pump part of the first stage is connected to the gas phase of the pump suction tank via the inside of the canned motor. It is characterized in that it is configured to be connected to the section.

In this case, the connection surface of the pump casing is formed such that the connection surface of the next stage pump casing is formed in a convex shape, and the connection surface of the previous stage pump casing is formed in a concave shape to fit and connect them in a liquid-tight manner. It is preferable that the pump chamber is provided within the convex portion of the pump casing of the next stage, and the discharge port of the previous pump section is provided in the pump casing of the next stage.

Further, the connection surface of the pump casing is configured such that the tLd surface of the next stage pump casing is formed in a convex shape, and the connection surface of the previous stage pump casing is formed in a concave shape, so that these are fitted and connected in a liquid-tight manner. The discharge port of the pump section at the previous stage may be formed by a groove formed in a convex portion of the pump casing at the next stage so as to be in contact with the inner periphery of the pump chamber at the previous stage.

Furthermore, the centrifugal impeller in the pump casing at the front stage of the cage may be configured with an impeller having radial straight blades.

[Function] The vortex type canned motor pump according to the present invention is configured so that the pressure of the pump section of the previous stage pressurizes the motor chamber as well as the low pressure section of the pump section of the next stage via the communication passage. It is possible to reduce noise by preventing cavitation in the subsequent gap between the impeller and the scroll as well as in the enlarged low-pressure part at the outlet of this gap.Furthermore, the impeller in the first stage pump casing has radial straight blades. With this configuration, the performance of the pump section in this stage is such that the head remains constant even if the flow rate changes, and therefore, even if the flow rate of the vortex pump changes, the NPSHA (effective suction head) of the vortex pump always remains constant. .

Furthermore, by providing a bypass hole for waste removal in the pump casing from the next stage onward, the gas passes through the canned motor chamber and flows out to the gas phase section of the pump suction tank. Even if it flows into the front-stage impeller or radial vane, it will not affect the NPSHA of the vortex pump suction port.

As a result, it is possible to reduce pump noise and easily design and manufacture a vortex pump with stable pump characteristics.2 [Example] Next, an example of a vortex-type canned motor pump according to the present invention will be described. This will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of the vortex type canned motor pump according to the present invention, and FIG. 2 is a cross-sectional view taken along the line AA in FIG.
A cross-sectional view is shown.

That is, in FIG. 1, reference numeral 10 is 0. The pump section and 12 indicate a canned motor section.

In this case, a multi-stage pump in which a plurality of pump casings are arranged in series can be considered as a pump for obtaining a high head, but in the present invention, a vortex type canned motor pump composed of two pump casings will be explained.

That is, the pump section 10 includes pump casings 14a and 14b divided into two equal parts, and one of the casings 14a, which is the first stage, is provided with a suction port 16 in the center.

Further, the other casing 14b, which is the next stage (second stage), is provided with a circular pump passage 20, and this pump 7fL passage 2
A suction port 22 and a discharge port 24 are arranged adjacent to each other on the outer periphery of the device.

A circular recess 1 is formed on the joint surface of one casing 14a.
5a, and a circular convex portion 15b is formed on the joint surface of the other casing 14b, and these are fluid-tightly fitted and connected to each other. An impeller storage chamber 18 is formed.

The suction port 22 communicates with the inner circumferential portion of the first stage impeller storage chamber 18 via a flow path 26 as a communication path bored in the casing 14b, and also communicates with the first stage impeller storage chamber 18 side. The convex portion 15b @ 15c is grooved to form a stiff user portion 26a (see Fig. 2).

Therefore, this diffuser portion 26a can be easily grooved from the convex end face 15C side, and the groove portion is opened, but the recess 15a of the first stage casing 14a is
By fitting with the recess, the opening is sealed by the bottom surface of the recess.

The pump casing 14a configured in this way.

One end of a rotor shaft 28 of a canned motor section 12, which will be described later, is inserted into the center of 14b, and a radial open impeller 30 is rotatably mounted in the first stage impeller storage chamber 18. Inside, scrolls 34 and 36 made of a sliding material are arranged on both sides of the pump impeller 32, and one scroll 34 is fixed to the pump part 12-sink 14b, and the other scroll 36 is fixed to the sink 14b.
is fixed to a bearing housing 40 that supports a front bearing 38 provided at the end of the canned motor section 12, which will be described later.

Therefore, an annular pump chamber 42 is formed around the outer periphery of the pump impeller 32 which is sandwiched between the pair of scrolls 34 and 36. Note that a flow path 44 communicating with the front bearing 38 of the canned motor section 12 is provided on the center side of the scroll 34, 36, and this flow path 44 is connected to the scroll 34.
4.36 and the pump impeller 32 communicate with the pump chamber 42 through a gap formed at the joint surface between the pump impeller 32 and the pump impeller 32.

On the other hand, the canned motor section consists of a stator assembly 46 and a rotor assembly 48, the rotor shaft 28 is supported by a front bearing 38 and a rear bearing 50, respectively, and a front rotor chamber 52 is provided at both ends of the rotor assembly 48, respectively. A rear rotor chamber 54 is formed.

Further, one end of the stator assembly 46 is sealed with a flange type end plate 1.56, a bearing housing 40 supporting a front bearing 38 is fixed to the front side of the end plate 56, and a pump casing 14a is attached to the flange. , 14b are integrally connected and fixed.

On the other hand, the other end of the stator assembly 46 is also an end play)~5
8, and a bearing housing that supports the rear bearing 50 is fixed to the end play 1.58 to seal the rear rotor chamber 54.

In this case, a terminal box 62 for power connection is installed on the outer periphery of the stator assembly 46, and a through hole 64 is bored in the bearing housing 60 that seals the rear rotor chamber 54 to connect the external circulation tube 66. By constructing the impeller in the first stage pump casing with radial straight vanes, the performance of the first stage pump becomes the pump characteristic diagram shown in Figure 3, and the flow rate changes. However, the lift height remains constant.

In the figure, the reference symbol ■ indicates the pump characteristic curve of the radial straight vane, and the reference symbol ■ indicates the N P S HR characteristic curve of the radial straight vane. 2
5, the NPSHR of the vortex pump is much worse than that of the radial straight vane. Therefore, 1
When a receding vane impeller is provided as the stage impeller, the pump characteristic becomes the descending curve ■ shown in Figure 3, and the intersection point with the NPSHR characteristic curve ■ of the vortex pump, that is, the Meteor Q
1 is the maximum flow rate.

The first stage pump discharge plate Q has an amount obtained by adding the bypass amount q2 to the vortex pump inflow amount q1, and it is possible to flow up to the maximum Q2.

Therefore, even if the flow rate of the vortex pump changes, the NPSHA of the vortex pump suction port remains almost constant. That is,
By providing a waste removal bypass hole 25 in the second-stage pump cushioning 14b, the waste flows into the gas phase in the pump suction tank through the canned motor chamber, so that the waste is partially removed together with the liquid. Even if it flows into the low-pressure part of the pump, if it is the first stage impeller or radial straight vane, it will not affect the N P S HA of the vortex pump suction port.

Next, the operation of the vortex type canned motor pump configured as described above will be explained.

The rotor shaft 28 is rotated by the drive of the canned motor, and the radial open impeller 30 and the pump impeller 32 are rotated.
rotates. As a result, the pump handling liquid is sucked through the suction port 16 under the action of the first-stage radial open impeller 30 and flows into the flow path 26 . At this time, the pressure of the liquid is increased in the tiff user section 26a, and the liquid is guided to the suction port 22 of the pump chamber 42 that houses the vortex pump impeller 32. At this time, a portion of the liquid pressurized by the first-stage radial open impeller 30 passes through the bypass hole 25 and flows into the front rotor chamber 52 through the radial notch 41 of the bearing housing 40 .

The liquid that has flowed into the pump chamber 42 is transferred to this pump chamber 5. 6 The pressure is increased within 42 and discharged from the discharge port 24.

In this way, a portion of the pump handling liquid pressurized within the pump chamber 42 is transferred to the pump impeller 32 and the scroll 34 .
It flows into the low pressure section through the flow path 44 from the gap formed between the flow path 36 and the flow path 44 .

On the other hand, a portion of the liquid that has flowed into the rotor chamber 52 via the bypass hole 25 flows into the inner circumferential surface of the front bearing 38 and lubricates the front bearing 38. It joins with the liquid flowing in through the gap formed between them in the flow path 44, passes through the bushing 19 while pressurizing the pump flow path 20, and returns to the suction part of the first stage radial open impeller 30.

On the other hand, most of the liquid that has flowed into the rotor chamber 52 is guided to the inner peripheral surface of the rear bearing 50 through the gap between the stator and rotor and the rear rotor chamber 54, thereby cooling the motor section and lubricating the rear bearing 50. In this way, the pump handling fluid that has lubricated the rear bearing 50 is sent to the pump handling fluid supply tank via the circulation tube 66 that is installed upward from the through hole 64 that is not drilled in the bearing housing 64. Circulate.

However, according to the swirl type canned motor pump according to the invention, the scrolls 34 and 36 located on both sides of the swirl type pump impeller 32 are made of the same sliding material as the bearings 38 and 50 (PA is a carbon bearing). This functions as a thrust bearing for the rotor shaft 28, and facilitates the design of the clearance required for this type of pump. In this case, a part of the pump handling liquid guided into the pump chamber 42 flows into the gap between the pump impeller 32 and the scroll 34, 36 to lubricate the gap and at the same time effectively maintain a predetermined gap. be able to.

In addition, in summer or winter when there are large temperature differences, when the pump is stopped at night and started the next morning, the temperature inside the suction pipe becomes higher than the liquid temperature in the suction tank, causing the vapor pressure inside the suction pipe to increase. The liquid turns into scum in the suction pipe. This gas is pumped
7 8 It flows into the first stage impeller storage chamber 18 via the inlet 16, or sequentially flows into the differential user part 26a, the bypass hole 25,
It flows through the notch 41, the front rotor chamber 52, the rear rotor chamber 54, the through hole 64, and the circulation tube 66 to the outside of the pump section.

By configuring the vortex pump in this way, the discharge pressure of the first stage pump is transmitted through the bypass hole 25 to the front rotor chamber 52 and to the flow path 4 which is the low pressure section of the second stage pump.
4 and the pump flow path 20 to prevent cavitation in the gap between the second-stage pump impeller 32 and the scrolls 34 and 36 and in the enlarged part of the pump low pressure section at the outlet of this gap, thereby achieving noise reduction. Can be done.

That is, according to the experimental data, the pump specification is 401
/ In1n x 80 m; 2.21tW (50
In the case of H2), the noise of the conventional pump was 73 db(A), but the noise of the vortex pump of the present invention is 67 db(A).
A).

In addition, in order to configure the eddy current type canned motor pump according to the present invention so that it can be commonly used for different frequency power sources, the bearing link housing 40 that supports the flange type end play 1 56 and the front bearing 38 is required. This can be easily handled by interposing an annular spacer (not shown) of a predetermined thickness on the joint surface 70.

For example, as shown in FIG. 1, if a device without an annular spacer is designed for 60H2, when used with a 50H2 power source, by attaching an annular spacer to the joint surface 70, the pump impeller 32 and scroll 3
By adjusting the gap between the pump impeller 32 and the pump impeller 32, it is possible to maintain the pump performance constant even if the rotational speed of the pump impeller 32 changes.

[Effects of the Invention] As is clear from the embodiments described above, according to the vortex type canned motor pump according to the present invention, in the vortex 90 flow rate pump which has pump characteristics of low flow rate and high head, a plurality of pump casings are connected in series. By pressurizing the low-pressure part of the pump part of the latter stage as well as the motor house through the pressure of the former pump part or the communication passage, the low-pressure part of the gap between the impeller and the scroll in the latter stage as well as the enlarged part of the low-pressure part at the outlet of this gap are increased. It is possible to reduce noise by preventing cavitation in
An i-flow type pump with stable pump characteristics can be easily designed and manufactured.

Moreover, it has excellent effects such as solving all the problems that could not be solved with conventional vortex pumps, making it possible to easily manufacture pumps that take full advantage of the characteristics of vortex pumps, and significantly reducing manufacturing costs. has.

Although eight preferred embodiments of the present invention have been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the flow rate canned motor pump according to the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is a pump characteristic of the first stage pump of the present invention. FIG. 4 is a sectional view of a conventional vortex type canned motor pump. 10... Pump part 12... Canned motor part 14a, 14b... Pump casing 15a...
Concave portion 15b...Convex portion 15c...Convex end face 16...Suction port 18...Impeller storage chamber 1
9... Bush 20... Pump channel 22...
・Suction port 23...Blind plug 25...Bypass hole 24...Discharge port 26...Flow path 26a
... Diffuser part 28 ... Rotor shaft 30 ... Radial open impeller 32 ... Vortex pump impeller 34. 36 ... Scroll 38 ... Front impeller 40 ... Bearing housing 1 2 41.・Notch 42 ・Pump chamber 44 ・
...Flow path 46...Stator assembly 48...
・Rotor assembly 5o...Front bearing 52...
・Front rotor chamber 54...Rear rotor chamber 56...
Flange type end play 1 to 58...end play 1
・ 60...Bearing housing 62...Terminal box 64...Through hole 66...
・Circulation tube 70...Joint surface 3 Fl (33 Procedural amendment (method) 1. Display of the case 1990 Patent Application No. 97266 2. Name of the invention Eddy current type canned motor pump 3. Person making the amendment Case relationship with

Claims (4)

[Claims] (1) A pump section and a canned motor section in which a scroll made of a sliding material is arranged on both sides of a vortex pump impeller, and a plurality of pump casings forming an annular pump chamber are arranged on the outer periphery of the pump impeller. A vortex-type canned motor pump consisting of a centrifugal impeller is provided in the pump casing of the first stage, a vortex-type impeller is provided in the pump casing of at least the next stage, and the pump discharge port of the first stage is provided with a centrifugal impeller. It communicates with the suction port of the pump section of the next stage through the passage in the pump casing, and further, the pump casings of the next and subsequent stages are connected in the same way, and the pump casing of the last stage is connected to the pump section of the previous stage, respectively. , a bypass hole reaching the inlet of the next-stage pump casing is formed in each casing, and the outlet of the flow path of the first-stage pump is connected to the gas phase part of the pump suction tank via the inside of the canned motor. Features: Whirlpool type canned motor pump. (2) The connection surface of the pump casing is formed such that the connection surface of the next stage pump casing is formed in a convex shape, and the connection surface of the previous stage pump casing is formed in a concave shape, so that they fit and connect in a fluid-tight manner. 2. The vortex-type canned motor pump according to claim 1, wherein the pump chamber is provided in the convex portion of the pump casing of the next stage, and the discharge port of the previous pump section is provided in the pump casing of the next stage. (3) The connection surface of the pump casing is configured such that the connection surface of the next stage pump casing is formed in a convex shape, and the connection surface of the previous stage pump casing is formed in a concave shape, so that these are fitted and connected in a liquid-tight manner. 2. The vortex-type canned motor pump according to claim 1, wherein the discharge port of the pump part of the previous stage is formed by a groove formed in a convex part of the pump casing of the next stage so as to be in contact with the inner periphery of the pump chamber of the previous stage. (4) The vortex type canned motor pump according to claim 1, wherein the centrifugal impeller in the pump casing at the first stage is an impeller having radial straight blades.