JPH0441997A - Magnet pump - Google Patents

Abstract

PURPOSE:To reduce held-up volume of gas and realize stable operation of a pump by separating liquid and gas in a pump chamber utilizing to centrifugal force due to rotation of an impeller, and by introducing the held-up gas in the pump chamber outwards after flowing through an impeller through sucking the gas to a negative pressure portion in a downstream of the nozzle. CONSTITUTION:When a pump is rotated by feeding current to a coil 39, and gas-liquid two-phase fluid flows into a pump from a suction port 4, a part mainly composed of liquid in the fluid in a pump chamber 19 is pressed against an outer side of the pump chamber 19 due to action of blades 25, and gaseous part comes together near the rotary axis X of an impeller 2 owing to specific gravity separating action of centrifugal force. In this case, part of gas bubbles is transfered to a downstream of the pump from a discharge port 5 through a nozzle 51, and the rest comes together at the central portion 53 in the pump chamber 19 outside the impeller 2. When the fluid mainly composed of liquid flows out from the nozzle 51 toward the discharge port 5, a negative pressure part is produced in the down stream of the nozzle 51. Consequently, the gas held up at the central portion 53 in the pump chamber 19 is sucked and flowed away outward the pump from the discharge port 5 together with liquid.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a so-called centrifugal magnet pump in which an impeller embedded with a magnet is rotationally driven by an external magnetic force. Regarding centrifugal magnetic pumps suitable for transferring gas-liquid two-phase fluids containing gas, they are used to pressurize highly foaming chemical solutions such as mixed solutions of sulfuric acid and hydrogen peroxide in semiconductor manufacturing processes.
This invention relates to a magnetic pump suitable for transporting and circulating filtration.

[Conventional technology]

BACKGROUND ART Conventionally, positive displacement pumps are often used to transport gas-liquid two-phase fluids in which gas is mixed in the liquid or fluids with high foaming properties that are solutions near the boiling point because they can maintain stable performance. However, positive displacement pumps are not always satisfactory because they need to be large to transfer a large flow of liquid, and the lifespan of the positive displacement pumps themselves is short. There are some devices that have been devised in various ways to transport fluids that are a mixture of gas and liquid.

FIG. 2 is a longitudinal cross-sectional view of a conventional centrifugal pump suitable for gas-liquid two-phase fluids. In the figure, 1 is a casing, 2 is an impeller housed inside the casing l, 3 is a main shaft for rotating the impeller 2, and 4 is a suction port through which liquid and air bubbles G mix and flow. , 5 is a discharge port through which the liquid and gas G flow out, 6 is a return pipe that returns the liquid from the discharge port 5 side pressurized by the impeller 2 to the suction port 4 side, and 7 is attached to the tip of the return pipe 6. This is the nozzle that was used. This centrifugal pump divides air bubbles G with a relatively large particle size flowing in from the suction port 4 into air bubbles G with a smaller particle size by a water flow from a nozzle 7 arranged upstream near the impeller 2. , so that there is no large impact when the impeller 2 receives centrifugal force.

FIG. 3 is a schematic diagram of a pump device showing another conventional example. In the figure, 8 is a centrifugal pump, the casing 1 of the pump is provided with a suction port 4 and a discharge port 5, and a gas-liquid separator 10 is arranged upstream of the suction port 4. Gas-liquid two-phase fluid flowing in from the inflow pipe 16 is separated into gas and liquid due to the difference in specific gravity, and only the liquid flows into the pump 8 . On the other hand, an ejector 15 is arranged downstream of the discharge port 5 of the pump, and sucks the gas accumulated in the upper part of the gas-liquid separator 10 via the exhaust pipe 14. Further, the other end of the condensate pipe 13 branched from the downstream side of the ejector 15 is connected to the gas-liquid separator 10, and a valve 17 is provided at the connection part. The float 12 is operated to open and close depending on the height of the liquid level 11 in the gas-liquid separator 10, and when the liquid level 11 in the gas-liquid separator 10 is low, it opens and the liquid flows from the condensing pipe 13 into the gas-liquid separator 10. The liquid flows into the gas-liquid separator 10 to maintain the liquid level 11 high and is exhausted, and the liquid level 1
1 is above a predetermined height, exhaust is performed only by operating the ejector 15, and the gas-liquid two-phase fluid is pressurized and transferred using a centrifugal pump.

FIG. 4 is a longitudinal sectional view of another conventional example of a magnetic pump using a radial gap type magnetic coupling. In the figure, l is a casing, and the casing 1 is made up of a suction casing 43 having an inlet 4 and an outlet 5, and a back casing 44. Inside the casing 1, an impeller 2 is rotatably mounted. A pump chamber 19 is formed to house the pump. The impeller 2 has blades 25, a permanent magnet 2o, and a main shaft 3 fixed together, and both ends of the main shaft 3 are rotatable by bearings 24 fixed to the suction casing 43 and bearings 24 fixed to the back casing 44. It is pivoted on. Permanent magnet 4 that gives rotation to the impeller
5 is fixed in an annular shape along the inner circumference of a magnet yoke 48 fastened to a drive shaft 47 of a motor 46, and the impeller 2 rotates by the urging of the motor 46, and the fluid to be transferred flows in from the suction port 4. The pressure is increased by the blades 25 and flows out from the discharge port 5. In this conventional example, the liquid-contact parts of the pump, that is, the casing 1, impeller 2, and bearing 24, are made of resin or ceramic to provide corrosion resistance.

This magnet pump is not particularly suitable for transporting fluid containing air bubbles, but is exemplified as a conventional example of an ordinary centrifugal magnet pump.

[Problem to be solved by the invention]

When operating a centrifugal pump that transfers gas-liquid two-phase fluid as described above, when a liquid containing gas G flows into the pump, when the gas mixing ratio (volume ratio) is small, the efficiency is The amount of drop (loss) in the pump head that is commensurate with the mixing ratio is sufficient.

However, when the amount of mixed gas is further increased, impeller 2
Gas gathers in the low-pressure central part of the tube, and this gas gathers in large quantities to block the passage. If gas blocks the passage, the centrifugal force generated by the blades of the impeller acting on the gas is extremely small, so the pump's pressurizing function stops, and eventually the pump becomes inoperable.

The problems with each of the above conventional examples are as follows.

That is, in the conventional example shown in FIG.
By jetting pressurized water from the nozzle 7 sent through the
The bubbles are dispersed in the liquid as smaller bubbles g, allowing the bubbles to pass through the impeller 2 without clumping together, but in centrifugal pumps with high discharge pressure, the nozzle Although it is possible to expect the agitation effect of the pressurized water from 7, that is, the effect of dispersing the bubbles, it is not possible to increase the mixing ratio of bubbles because effective dispersion cannot be achieved with a pump with a low discharge pressure. There was a problem.

In addition, in the conventional example shown in Fig. 3, the gas-liquid separation effect in the gas-liquid separator IO is related to the flow rate and residence time, and when the flow rate of the pump is large, the residence time becomes short and small-sized bubbles are formed. cannot be separated. In such a case, it is necessary to increase the volume of the gas-liquid separator and lengthen the residence time, but this poses a problem in that the pump becomes larger.

Furthermore, when a gas-liquid two-phase fluid is transferred using the magnetic pump shown in FIG. It vibrates violently under load.

In this conventional example, the impeller 2 has a long dimension in the direction of the rotational axis, and the blade 25 at one end is the part that receives external force, and the impeller 2 has the permanent magnet 20 and the blade 25.
Since torsional stress is exerted on the portion 5, the impeller 2 moves in a complicated manner when subjected to an external force due to air bubbles, and the bearings 23 and 24 are unable to support the load.

Further, since the fluid inside the pump chamber 19 is subjected to centrifugal force by the impeller 2, liquid with a large specific gravity gathers on the outer circumferential side, and air bubbles gather on the rotation axis side, so that the bearing 23.
There is a problem in that there is no longer any liquid for lubrication in the portion 24, and in extreme cases, the pump may begin to be damaged due to a liquid shortage phenomenon at the bearings 23, 24.

SUMMARY OF THE INVENTION An object of the present invention is to provide a centrifugal magnetic pump that effectively transfers a gas-liquid mixed fluid in which gas is mixed in the liquid. The object of the present invention is to provide a centrifugal magnet pump that can stably transfer even if there is a large amount of mixed substances.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a magnet pump in which an impeller in which a permanent magnet is embedded is driven to rotate by magnetic force from the outside of the impeller. a pump casing having a pump chamber, one of which is fixed to the casing and the other of which is rotatably housed in the pump chamber of the casing and has a permanent magnet embedded therein; A means for rotationally driving the impeller by applying a magnetic force to a bearing fixed to the impeller and the permanent magnet in the impeller, the means being at a position opposite to the impeller in the direction of the axis of rotation of the impeller. a driving magnetic force mechanism provided in a non-liquid-contacted part of the casing;
It consists of a nozzle disposed on the discharge port side of the pump chamber, and a gas discharge path having one end opened in the vicinity of the rotation axis of the pump chamber and the other end opened downstream of the nozzle, This magnet pump is characterized in that a fluid inflow path that communicates the suction port with the pump chamber is formed through a central portion of the drive magnetic force mechanism.

[For production]

Since the present invention is configured as described above, the gas-liquid two-phase fluid flowing in from the suction port is mainly pressed against the outer circumferential side of the pump chamber by the action of the impeller, and the liquid is mainly pressed against the outer circumferential side of the pump chamber 1c. The gas flows out toward the discharge port from the nozzle disposed between the pump chamber and the discharge port, while the gas collects in the center of the pump chamber, that is, the part centered around the rotation axis of the impeller, and flows through the gas exhaust path. The liquid is sucked into a negative pressure portion formed downstream of the nozzle through the nozzle, and flows out together with the liquid from the discharge port of the pump.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of the magnet pump of the present invention. The casing 1 of the pump consists of a suction casing 1a having a suction port 4 for fluid, and a back casing 1b having a discharge port 5 for pressurized fluid.
A pump chamber 19 that accommodates the impeller 2 is formed by the rear casing 1b and the impeller 2 and the suction casing 1a.
A rotating side bearing 23 and a stationary side bearing 24 are respectively fixed to the pump chamber 19, and a nozzle 5 is installed on the discharge port 5 side of the pump chamber 19.
1 and a nozzle plate 52 on which a gas exhaust path 50 is formed are fixed to the back casing lb by bolts (not shown), and the pump chamber 19 and the suction port 4 are communicated through an inflow path 49. The materials of these parts constituting the casing 1 must be resistant to corrosion against the fluid to be transported depending on the purpose of the pump, but at least the suction casing 1a, which is placed in a magnetic field with high magnetic flux density, must be made of non-magnetic material. It is desirable that

The impeller 2 rotatably housed in the pump chamber 19 is
An annular permanent magnet 20 is glued and embedded in the side surface of the suction casing la of an annularly molded magnet yoke 21, and after these metal members 20 and 21 are entirely sealed with a quartz cover 22, The entire body is covered with a non-magnetic material such as nylon or fluorocarbon resin, sealed by a known means such as welding or welding, and the metal member 2 is doubled.
0.21 to prevent fluid from entering. Furthermore, impeller 2
is equipped with wings 25 in order to achieve a predetermined pump performance, and in the figure, a main plate 26 is installed to increase pump efficiency.
is attached and has a closed blade.

A fixed side bearing 24 made of ceramic with a spherical concave surface facing the impeller 2 is screwed into the inner surface of the suction casing la, that is, the part facing the pump chamber 19.
A rotating side bearing 23 made of ceramic and having a spherical convex surface corresponding to the concave surface of the stationary side bearing 24 facing the concave surface is screwed into the portion of the impeller 2 that faces in the direction of the rotation axis X direction. A groove of about 10 microns is formed on either one of the concave and convex surfaces, and the two form a single spiral group bearing, and the sliding friction between the bearing 24 and the bearing 23 allows the rotation axis to be rotated in the X direction. Thrust load and rotational axis X
and a radial load in the right angle direction.

Further, a permanent magnet 31 that serves as a drive magnetic force mechanism, which is a means for applying magnetic force to a permanent magnet 20 embedded inside the impeller 2 to rotationally drive the impeller 2, is installed in the suction casing la. The permanent magnet 31 is arranged in a non-liquid-contact part, and is fixed to a magnet yoke 32 that is rotatably supported by a ball bearing 36. A coil 39 is integrally fixed to a rotor consisting of
The impeller 2 is rotatably driven by energization, and a fluid inflow path 4 communicates the suction port 5 and the pump chamber 19 along the rotation axis X direction of the impeller 2 at the center thereof.
9 is formed.

Here, when electricity is supplied to the coil 39 and the pump rotates at the rated rotational speed, and gas-liquid two-phase fluid, which is a mixture of gas and liquid, flows from the suction port 4, the fluid in the pump chamber 19 is , mainly the liquid part is pressed against the outer circumferential side of the pump chamber 19 by the action of the blades 25, and the gas part collects in the vicinity of the rotation axis X of the impeller 2 due to the specific gravity separation effect of the centrifugal force. do.

Although it depends on the size of the bubbles flowing in from the suction port 4, if the diameter of the bubbles is small, the speed of the bubbles passing through the impeller 2 will be affected by the specific gravity separation effect of the centrifugal force accompanying the rotation of the impeller 2. A part of the bubbles overcomes the liquid and flows out from the outer periphery of the impeller 2, and a part of the bubbles immediately passes through the nozzle 51 and is transferred from the discharge port 5 to the downstream of the pump, while the other part of the bubbles flows out of the impeller 2. They gather at the center 53 inside the external pump chamber 19.

When a fluid mainly composed of liquid flows out from the nozzle 51 toward the discharge port 5, a negative pressure portion is generated downstream of the nozzle 51, and this negative pressure portion and the central portion 53 in the pump chamber 19 where gas is retained. Since these are in communication with each other through the gas exhaust path 50, the gas staying in the center 53 of the pump chamber 19 is sucked into the negative pressure area generated downstream of the nozzle 51 and is pumped out from the discharge port 5 together with the liquid. leak outside.

In the state shown in Fig. 1, when the pump rotates at the rated speed and gas-liquid two-phase fluid flows in from the suction port 4 and flows out from the discharge port 5, what is the discharge amount of the pump? Even if there is a force, the magnetic force acting on the impeller 2 is always a force that attracts the permanent magnet and the impeller 2, which constitute the drive magnetic force mechanism, to each other, and a force that causes the fluid to press the impeller 2 in the direction of the rotation axis X. is a force that always presses the impeller 2 toward the driving magnetic mechanism, so the impeller 2 rotates close to the driving magnetic mechanism, and there is no unstable region caused by these, and Due to the high rigidity of the fluid film formed on the bearings 23, 24, irregular stresses resulting from the presence of air bubbles can be supported in the best possible manner.

In the figure, a ceramic spherical groove bearing is used as the bearing, but other bearings with a conical groove shaft can support both radial load and thrust load with one set of bearings. Therefore, it is suitable.

Further, although a rotatably supported permanent magnet 31 is illustrated as a drive magnetic force mechanism which is a means for giving rotation to the impeller 2 by magnetic force, a stator is formed by arranging coils in a ring shape, and the suction casing 1a The impeller 2 may be directly rotated by being fixed to a non-wetted part of the impeller 2.

〔Effect of the invention〕

As explained above, the magnet pump of the present invention is a magnet pump in which an impeller in which a permanent magnet is embedded is rotationally driven by magnetic force from the outside of the impeller. A pump casing having a pump chamber accommodated therein; and an impeller rotatably housed in the pump chamber of the casing and having a permanent magnet embedded therein; one is fixed to the casing, and the other is fixed to the impeller. A means for rotating the impeller by applying a magnetic force to a bearing fixed to the impeller and the permanent magnet in the impeller, and a position facing the impeller with respect to the rotational axis direction of the impeller. a driving magnetic force mechanism provided in a non-wetted part of the casing; a nozzle provided on the discharge port side of the pump chamber; one end opening in the vicinity of the rotation axis of the pump chamber;
The other end is composed of a gas discharge path opened on the downstream side of the nozzle, and a fluid inflow path communicating the suction port and the pump chamber is formed passing through the center of the drive magnetic mechanism. , has the following effects.

(b) When transferring a fluid containing a mixture of gas and liquid, the liquid and gas are separated inside the pump chamber by centrifugal force based on the rotation of the impeller, pass through the impeller, and remain in the pump chamber. Gas gathers in the center of the pump chamber, is sucked into the negative pressure section downstream of the nozzle through the gas exhaust path located here, and is led to the outside of the pump, so the amount of gas stagnant in the pump chamber is significantly reduced. , stable operation is possible.

(b) Conventionally, when gas-liquid two-phase fluid is transferred using a centrifugal pump, uneven stress acts on the impeller due to the presence of some air bubbles, which tends to cause large shocks and large loads on the impeller. Vibratory forces were added, which sometimes even caused damage to the pump, but with the magnetic pump of the present invention,
Bearings that support these loads are placed between the drive magnetic force mechanism, which is the means for rotationally driving the impeller, and the permanent magnet embedded in the impeller, so that the vibration of the impeller, which is a single rotating body, is can be effectively supported, and vibration of the pump can be reduced.

(During the rated operation of the glue pump, the magnetic force acting between the drive magnetic force mechanism and the impeller is always a force in the direction of bowing each other, and the fluid pressure is a force that presses the impeller toward the drive magnetic force mechanism. Therefore, the impeller always rotates close to the casing, and therefore the fluid film at the bearing has high rigidity, and irregular stresses on the impeller caused by the influence of air bubbles present in the fluid are eliminated. can be effectively supported.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of the magnet pump of the present invention, Fig. 2 is a longitudinal sectional view of a conventional example, Fig. 3 is a schematic diagram showing another conventional example, and Fig. 4 is a longitudinal sectional view of yet another conventional example. It is a diagram. 1...Casing, 1a...Suction casing, lb
... Back casing, 2... Impeller, 4... Suction port, 5... Discharge port, 19... Pump chamber, 20...
Permanent magnet, 21... Magnet yoke, 22... Quartz cover, 23... Rotating side bearing, 24... Fixed side bearing, 25... Wing, 26... Main plate, 31... Permanent Magnet, 32... Magnet yoke, 33... Reinforcement plate,
34...Casing cover, 36...Bearing,
3B... Iron core, 39... Coil, 40... Permanent magnet, 41... Magnet yoke, 49... Inflow path,
L: Liquid, G: Bubbles (large particle size) X: Rotating shaft core. Figure 1

Claims (1)

[Claims] 1. A magnet pump in which an impeller in which a permanent magnet is embedded is rotationally driven by magnetic force from outside the impeller, a pump casing having a suction port, a discharge port, and a pump chamber in which the impeller is housed; an impeller that is rotatably housed in the pump chamber of the casing and has a permanent magnet embedded therein; a bearing that is fixed on one side to the casing and on the other side to the impeller; A means for rotationally driving the impeller by applying a magnetic force to the permanent magnet, the drive being provided in a non-liquid-contacted part of the casing at a position facing the impeller with respect to the rotational axis direction of the impeller. a magnetic force mechanism; a nozzle disposed on the discharge port side of the pump chamber; and a gas discharge path having one end opened in the vicinity of the rotation axis of the pump chamber and the other end opened downstream of the nozzle. A magnet pump, characterized in that a fluid inflow path communicating the suction port and the pump chamber is formed through a central portion of the drive magnetic force mechanism.