Vertical submerged pump for chemical application

Abstract

The present invention discloses structural improvement of the vertical submerged pump for chemical application. The present invention is focus on reducing the crystal lump generated from high speed etching process. Structural improvement includes a shaft seal device, a diffuser and an upper inner plate. The shaft seal device offer extra flow resistance to balance the differential pressure between the inner space and pump front casing, the function are prevents air bubbles be sucked into the pump, and reduces flow leakage from the front casing into inner space, also absorbs high-pressure back-flush to avoid liquid splash in dry surface of inner space of support column. The diffuser in the support column offer extra inducer function to guides the liquid from the inner space flowing out to the tank, so as to get a stable liquid level in the inner space, thereby largely reducing splashing of the liquid. And the upper inner plate blocks the residual small amount drops from liquid splashing, to minimize producing of crystals lump from high speed etching liquid.

Description

BACKGROUND OF THE INVENTION

a) Field of the Invention

The present invention relates to the structural improvement of a vertical submerged pump for chemical application, and more particular in high speed etching process in PCB manufacturing, owing to the drops from splashing of process liquid easily become crystal when attach to dry surface and contact with air, the crystal will damage the shaft seal and lead motor to be broken, so as to reduce liquid splashing from pump shaft to avoid generation of crystals is an important issue. The present invention improve the structure to control the liquid level in an inner space of a support column of a submerged vertical pump, especial when the process liquid is at over upper liquid level, thereby decreasing damage to a shaft seal of a motor, and avoiding the corrosive vapor entering into the motor to cause malfunction.

b) Description of the Prior Art

Referring to FIG. 1, a conventional vertical submerged pump is used in chemical plating or etching process to transfer strong acid, strong base or corrosive liquid. A practical operation is described as follows. A cantilever shaft 3 be installed inside the support column 1, and at the lower side of the cantilever shaft 3 is directly connected with the hub 52 of impeller 5. At rear side of the impeller 5 is provided with back vanes 51 to balance axial thrust. The impeller 5 is provided in a front casing 4 which is opened with an inlet port 44. A side of the front casing 4 is opened with an outlet port 45 which is connected to a discharge pipe 43. In a real condition, liquid sucked flow in the inlet port 44 by the impeller 5 along the direction 28, is pressurized flowing through a flow channel of the impeller 5 and is then discharged from the outlet port 45.

When the pump operates, the shaft sleeve 31 of the cantilever shaft 3 has a tangential velocity U (as shown in FIG. 2) at outer surface, will drive the liquid in the inner space 12 to flow in free vortex 2 with a distribution of the tangential velocity 267 shown in the drawing. The free vortex 2 is also provided with a stream line of a secondary flow 22 with lower kinetic energy, and at the center of the vortex is formed with a hollow space 21 which is as a funnel extended downward. A flow direction of the free vortex 2 is also provided with the stream line of the secondary flow 22 on an r-z cross section at the same time, and the hollow space 21 is a primary zone where air 24 be sucked and mixed with the liquid to produce bubbles 241, allowing the back vanes 51 to attract the bubbles 241 to flow downward. For example, the liquid which contains bubbles 242 flows through the clearance of back cover 42 between back cover and the shaft, and then enter into the front casing 4, bubbles 242 will be pressurized into bubbles 243 in smaller diameters and exported through the discharge pipe 43 from the outlet port 45. The bubbles also flow through lower holes 11 of the support column 1, diffuser holes 112 of the support column I and upper holes 111 of the support column 1 into the tank along the direction 23.

Referring to FIG. 2, after the liquid that is close to a surface of the shaft sleeve 31 of the cantilever shaft 3 receiving kinetic energy of rotation of the pump, a tangential velocity distribution Cu will be close to the tangential velocity U at the outer surface of the shaft sleeve 31 of the cantilever shaft 3. However, a free surface of free vortex 2 has the energy conservation feature from Bernoulli theorem, the energy conserve with kinetic energy, that is velocity, and potential energy, that is liquid level reference from tank level. The total energy is transferred from the shaft to the liquid and the free surface of the free vortex 2 has the same energy, and the energy will convert to both kinetic energy and potential energy, it depend on the tangential velocity which is low or high, if tangential velocity is low then the potential energy must be high, that means liquid level is high. The tangential velocity distribution Cu of the free vortex 2 decreases as the radius r increases, and is inverse proportional to the radius r (r⁻¹); therefore, at the central part of the free vortex 2, the liquid level will form a funnel which is extended downward due to the fast tangential velocity, that is the maximum flow speed as same as the tangential speed of rotational shaft 3. On the other hand, as the tangential velocity Cu slow down toward the outer edge 2A of the free surface, the potential energy will become higher, that allows the liquid level to be higher than both the hollow space 21 and the tank 29.

Referring to FIG. 3, when the pump discharge capacity become larger, the output pressure will become smaller, and at the same time if the liquid level of the tank 29 is lower, in this condition a low pressure suction force will be generated by the back vanes 51 of the impeller, owing to the force acting on the liquid by the back vanes 51, and establish a low pressure zone near the impeller hub 52. The pressure of the low pressure zone maybe is negative pressure in vacuum at some time, when the low pressure is sufficient to overcome the output pressure of the pump, which liquid and air 24 will be sucked and through the clearance 42 at the back cover into the front casing 4, especially the liquid level at the central part of the free vortex 2 will be low. Although the support column 1 is provided with lower holes 11 to supplement the liquid from the tank, with the liquid flowing in along a direction 26, the liquid level at the outer edge surface 2A of the free vortex 2 in the inner space 12 is as low as the liquid level in the tank 29. If this condition continuously happen, the liquid level of the hollow space 21 will descend significantly or even reach to the back cover 41, allowing the air bubbles 24 to be sucked into the front casing 4 through the clearance 42 at the back cover, which will cause the pump to operate unstably by sucking in the air bubbles and result in an unstable output of the pump.

Referring to FIG. 4, when the pump discharge capacity is smaller, the output pressure become larger, and the liquid level in the tank 29 is kept high or over level limit, that is a high liquid level manufacture process. At this condition the low pressure suction force of the back vanes 51 is not sufficient to balance the high output pressure, and the high pressure liquid will leak out through the clearance 42 at the back cover 41 along a direction 262 and flow into the inner space 12. Owing to the leakage, the liquid level will increase in the inner space 12, the free surface of the free vortex 2 will rise, and especially the outer edge 2A of free vortex 2 will become higher even over the level limit. Although the support column 1 has some openings with lower holes 11, diffuser holes 112 and upper holes 111, but the circumference flow 25 is in tangential flowing, owing to the liquid receiving the rotational kinetic energy transferred from the shaft, so the liquid has strong momentum in circumferential direction and weak in radial direction, the liquid is not easily to flow through the openings 112 out, that is more liquid leakage in and less liquid flow out, the liquid will gradually accumulate in inner space 12 of support column 1. Therefore, the liquid level at the outer edge surface 2A of the free vortex 2 will be over the level limit finally, and the liquid could be very close to the undersurface of the motor mounted plate 61. In addition, some liquid will be splashed on surfaces of a seat of a V-type oil seal 64, a ceramic seal ring 71 and a V-type oil seal 72, further producing crystal lumps on these surfaces to damage the V-type oil seal 72. Moreover, corrosive vapor can enter into the motor to result in malfunction.

Referring to FIG. 5, when the pump shuts down, the impeller 5 will not generate high pressure any more. At this time, the high pressure liquid and compressed air in filtration tanks of the piping system will back flush 271 momentarily from the discharge pipe 43. This kind high kinetic energy is converted from pressure potential energy of compressed air and high pressure liquid, the back-flush 271 will flow backward out through the inlet port 44 along the direction 281, and will flush toward the back vanes 51 also. So back-flush 264 with high kinetic energy flow upward through the clearance 42 at the back cover 41 out, and the back-flush 265 will enter into the inner space 12, in the same time the liquid in the inner space 12 still kept in free vortex motion, such that the lowest level of the hollow space 21 in the vortex center cannot absorbs the kinetic energy of back-flush 265, and part of the back-flush 266 will spray and splash upward. Especially that during a high liquid level manufacturing process, the back-flush 266 wilt spray onto the dry undersurface 61 of the motor mounted plate, around the shaft hole 62 of the motor mounted plate, the ceramic seal ring 71 and the V-type oil seal 72. The spraying liquid left to produce crystals when it become dry, this will damage the ceramic seal ring 71 and the V-type oil seal 72, and further concern the liquid vapor to penetrate into the motor, which will damage motor bearing and the winding.

Concluding the aforementioned pump operation phenomena, for the application of a high-speed etching process, providing a low-cost solution to stop the crystal lumps formed by liquid splashing will satisfy existing requirements of customers; whereas, issues of problem that the solutions to be faced with are:

• • (1) The problem of liquid splashing at the outer edge 2A of the free vortex 2 in the high liquid level manufacturing process,
  • (2) The problem of high pressure back flushing in the piping system when the pump be shut down and,
  • (3) The problem that the air bubbles are sucked into the back vanes of the impeller in the low liquid level manufacturing process.

To completely solve the problems, each problem needs to be analyzed in details. The cause analyses are described as follows:

• • (1) The liquid splashing problem: the majority issue is about the liquid level, include the tank liquid level is at high liquid level limit, and also the liquid leaks from front casing into the inner space result in liquid level increasing in inner space till over upper level limit. And another issue is the liquid in free vortex motion in the inner space but the openings on support column are still difficult to let the liquid flowing out to keep the liquid level in stable.
  • (2) The back flushing problem: It is un-normal operation problem of equipment or piping system by operator, but it always happen because operator's problem, especially the compressed air accumulated in filtration tanks conditions. Therefore, the pump should be equipped with a device to isolate, guide and absorb the pulse wave of high-pressure back-flush, that let any operator does not worry about this.
  • (3) The air bubbles sucked-in problem: Sometimes the liquid level in the tank could be low or beyond the low limit. Therefore, the pump should be designed to isolate the low pressure of the back vanes of the impeller and to guide the liquid into the pump casing, so as to prevent larger amount air bubbles from being sucked in to result in an unstable operation.

There are already some solutions to solve the aforementioned problems. One of the solutions is the patent TW221338, which discloses a non-contact labyrinth type seal device of a submerged vertical pump. The patent provides a solution to solve the problems, that the non-contact labyrinth type seal device offer a extra flow resistance to balance the differential pressure between the inner space and the front casing, that is the air bubbles will not be sucked, even a negative pressure produced from the back vanes of the impeller, and the high-pressure liquid flushes back from the piping will be isolated when the pump shuts down. However, this solution is not able to control the liquid at the outer edge of the vortex from splashing, and the leakage become slowly but still leakage from front casing, it will increase the liquid level during the operation till to over liquid level limit, especially liquid tank has a high liquid level conditions, and the last issue of the solution is the reliability of labyrinth type seal device.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a vertical submerged pump for chemical application. Structural improvement includes a shaft seal device, a diffuser and an upper inner plate. The shaft seal device offer extra flow resistance to balance the differential pressure between the inner space and pump front casing. The function are prevents air bubbles be sucked into the pump, and reduces flow leakage from the front casing into inner space, also absorbs high-pressure back-flush to avoid liquid splash in dry surface of inner space of support column, and has reasonable reliability. The diffuser in the support column offer extra inducer function to guides the liquid from the inner space flowing out to the tank, so as to get a stability liquid level in the inner space, thereby largely reducing splashing of the liquid. And the upper inner plate blocks the residual small amount drops from liquid splashing, to minimize producing of crystals lump from high speed etching liquid.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As indicated in FIGS. 6, 7, 8, 9, 10 and 11, the present invention is a vertical submerged pump for chemical application. The structural improvement includes a shaft seal device 55, a diffuser 10 in a support column and an upper inner plate 83 in a support column. The structural improvement comprises of:

A shaft seal device 55 having a rotor of N-type seal 53 and a stator of N-type seal 54. The stator 54 is provided at a corresponding position in the rotor 53 after the pump has been assembled, an out surface of the rotor 53 and an inner surface of the stator 54 matching each other to form a non-contact seal channel 56. The seal channel 56 has two sharp turns with a bending angle of each turn larger than 90°, and has a more than I mm width to improve the reliability. The stator 54 is provided with an outer cylindrical part 543 and a plate part 548 that the stator 54 can be provided on an inner wall of an upper part 46 of the front casing 4 by the plate part 548. The rotor 53 can be provided on an impeller hub 52 by an inner diameter 536 of the rotor. The stator 54 is provided with two inner surfaces 549 of different radii and a conical part 542 which is extended downward. The rotor 53 is provided with two inner surfaces 532 of different radii and a conical part 531. The conical part of the stator 542 is provided to fit with the conical part 531 of rotor 53, and the two form a conical part 561of the seal channel 56 to extend a seal length of the seal channel 56, so the seal channel 56 could offer extra flow resistance to balance the differential pressure between the inner space 12 and the front casing 4. The first sharp turn 564 at the seal channel 56 on the stator 54 is provided with plural radial stator holes 544 which are connected to the inner space 12, and the second sharp turn 565 at the seal channel 56 on the rotor 53 is provided with radial rotor holes 533 to remove impurities accumulated to release into inner space 12, the shaft seal device could absorb the kinetic energy of the back-flush high-pressure pulse wave and guide the liquid into inner space then enter the liquid tank.

A diffuser 10 in the support column guides partially the liquid direction from circumferential direction to radial direction, that is increase the radial velocity component and reduce the tangential velocity. So the liquid will flow out in a small turning angle to increase radial velocity, and some of the kinetic energy be converted into velocity in radial direction to go outward. Accordingly, the structure of the diffuser 10 in the support column 1 could provide a diffusing function and a flow turning function to keep the liquid level in stable at inner space 12. The diffuser blade 14 has an incident angle a between the inlet flow of the liquid and the inlet of the diffuser blade 14, such that the liquid will not change the direction significantly at the leading edge 141 of diffuser blade 14. After the liquid flowing through the cascade the liquid velocity will be slow down and the flow angle will be change by the diffuser blade 14, this is a diffusion process relative about some of the kinetic energy in circumference will be converted to velocity in radial flowing, and the liquid will flow out through the diffusion holes 15. So the diffuser 10 can be easily manufactured and installed, as well as cost can be reduced. Three embodiments are listed as follows:

First embodiment of the diffuser 10 in the pump column 1 is plural blades 14 with span B, which are installed inside the support column I and arranged alternately with plural diffuser holes 112 into circular. In addition, the blades 14 are installed opposite to a direction of the circumferential flow 25. A leading edge 141 of the diffuser blade 14 faces toward the circumferential flow 25, and located above the diffuser hole 112, a trailing edge 142 of the diffuser blade is below the next diffuser hole 112, and a cross section 145 of the diffuser blade is a smooth arc shape. A flow channel 146 is formed between the diffuser blades 14, the diffuser hole 112 is located on the wall of the support column 1 in the flow channel 146, an inlet 147 of the flow channel is constituted by the leading edges 141 of the neighboring diffuser blades, an outlet 148 of the flow channel is constituted by the trailing edges 142 of the neighboring diffuser blades. The free vortex 2 has liquid flow 25 in horizontally circumference direction, an incident angle a is formed between the leading edge 141 of the diffuser blade and the circumference flow 25, and the liquid enters from the inlet of the flow channel 147 and is guided to flow downward to export from the outlet of the flow channel 148. When the liquid flows in the flow channel 146, the diffuser blade 14 will absorb some of the kinetic energy of the liquid to locally increase a static pressure at the flow channel 146, allowing a bigger pressure difference between the inner wall and the outer wall of the support column 1. This pressure difference allows the liquid to accelerate out from the diffuser hole 112 and this guiding effect facilitates expelling the excessive liquid in the inner space 12 and keeps the liquid level stable, thereby avoiding the liquid level at the outer edge surface 2A of the vortex to reach to an upper inner plate 83 of the support column.

A second embodiment of the diffuser 10 in the support column 1 is with plural diffuser holes 15 only, which are arranged in a circumference of the support column 1 to replace the original diffuser holes 112. The diffuser holes 15 have an oblique opening and form a small bevel angle β with the circumference flow 25, so as to induce the liquid to flow out by convert the tangential velocity partially to increase a radial component of the velocity. When the circumference flow 25 driven by the pump shaft 3, the side wall 153 of the diffuser holes 15 will induce the flow along the wall, and another side wall 154 of the diffuser holes 15 allows the liquid to turn along the diffuser holes 15, this effect is similar like an water cut or a tongue of a volute pump casing; that is, the radial velocity component of the liquid will increase as flow 26, and more liquid will flow along the diffuser holes 15 out, and hence, the liquid will be stable by the diffuser holes 15.

A third embodiment of the diffuser 10 in the support column 1 is plural longitudinal blades 16 with span B, which are installed in the interior side of the support column 1, and are arranged alternately with plural longitudinal diffuser holes 17 in circumference. The leading edge 161 of the diffuser blade 16 faces toward the circumference flow 25, the root 162 of the diffuser blade 16 is located at the side wall 174 of the long diffuser hole 17 and a cross section of the diffuser blade 16 is a smooth arc shape. A flow channel 166 is formed by the diffuser blades 16, the inner wall of support column 1, and the longitudinal diffuser hole 17. The inlet 167 of the flow channel 166 is constituted by the leading edges 161, the outlet 168 of the flow channel 166 is the longitudinal diffuser hole 17. The circumference flow 25 with the leading edge of the diffuser blade 161 forms an incident angle γ, the root of the diffuser blade 162 has angle δ with the circumference. The liquid enters from the inlet 167 of the flow channel 166, and is guided to flow outward from the longitudinal diffuser hole 17, with smoothly flow angle δ, so as to facilitate the liquid to flow out with the radial velocity component of the velocity as flow 26.

An upper inner plate 83 is a ring-shape plate structure, is installed on interior wall of the support column 1 and is closed to a lower rim of the upper hole 111. The cantilever shaft 3 passes through the center of that ring-shape structure, and keeps a large radial distance with an outer diameter of the shaft sleeve 31. When the liquid level of the free vortex 2 keeps at a certain height by the diffuser blade 14, there is still a small amount of the liquid will splash above the support column 1 from the outer edge surface of the vortex 2A. The upper inner plate 83 can further isolate the splashing liquid, prohibiting the liquid to reach to a undersurface of a motor mounted plate 61, and keeping surfaces of a seat 64 of V-type oil seal 72, a ceramic seal ring 71 and a V-type oil seal 72 clean that the V-type oil seal 72 will not be damaged by the crystals, thereby effectively isolating acid vapor to assure that the motor will not be malfunction.

Referring to FIG. 7(a), it shows a perspective view of a shaft seal device 55. Referring to FIGS. 6 and 7(b), a shaft seal device 55 has a rotor 53 and a stator 54, wherein after the pump has been assembled, the rotor 53 is installed at a corresponding position in the inner diameter 549 of the stator 54. The impeller hub 52 be fixed at the end of the cantilever shaft 3 installed with the shaft sleeve 31, and pass through the inner diameter 536 of the rotor. The stator 54 uses a structure having a plate part 548 of the stator 54 to facilitate installation and positioning, or only a structure of an outer cylindrical part of the stator 543 is used, referring to FIG. 7(c). The stator 54 can be provided with a screw part 547, such that the stator 54 can be installed into a screw hole at the upper part of the front casing 46, or the stator 54 can be installed into an opening at the upper part of the front casing 46 by other methods.

Referring to FIG. 8, it shows a cross-sectional drawing of a shaft seal device 55 be assembled on the vertical submerged pump. Wherein the rotor 53 is a cylindrical structure which is constituted by two cylinders of different radii, the cylindrical part of the rotor 534 and the inner surface of the rotor 532 are linked together by the conical part of the rotor 531 which is extended upward. At bottom of the conical part of the rotor 531 is provided with plural rotor holes 533 to remove impurities which be accumulated in the seal channel 56, thereby protecting the seal channel 56 from being expanded by wearing out. The stator 54 comprises the plate part 548 and the outer cylindrical part 543. At interior of the outer cylindrical part 543 is provided with the conical part 542 of the stator 54 which is extended downward, and a top of the conical part 542 is provided with plural radial stator holes 544 which are used to transfer the back-flush pressure wave and are connected to the inner space 12. After the pump has been assembled, the stator 54 and the rotor 53 will constitute the seal channel 56 which has an inlet 562 and an outlet 563, the two are of different radii, as well as a conical part 561 of the seal channel 56. The conical part 561 of the seal channel 56 is located between the inlet 562 and the outlet 563 of the seal channel. When the liquid flows from the inlet of the seal channel 562 toward the conical part 561 of the seal channel 56, the liquid must flow backward by more than 90° at the first sharp turn 564, and when the liquid flows from the conical part of the seal channel 561 toward the outlet of the seal channel 563, the liquid should also flow backward by more than 90° at the second sharp turn 565, and vice versa when the liquid flows reversely. A highly flow resistance loss will be produced in the seal channel 56 with two sharp turns, even the width of seal channel 56 is more than I mm. The conical part 561 of the seal channel 56 is formed by matching the conical part 531 of the rotor with the conical part 542 of the stator, the inlet 562 and outlet 563 of the seal channel 56 are formed by the inner diameter 549 of the stator 54 and the outer diameter 537 of the rotor 53, which are of different radii. The first sharp turn 564 of the seal channel 56 corresponds to the plural stator holes 544 which are connected to the inner space 12, and the second sharp turn 565 of the seal channel 56 corresponds to the plural rotor holes 533 which are connected with the inlet 562 and the outlet 563. A small amount of the high-pressure liquid in the front casing 4 will flow in from the rotor holes 533, thereby removing the impurities which are accumulated in the seat channel 56.

Referring to FIG. 9(a) when the pump operates in the low liquid level condition, a shaft seal device 55 offers extra flow resistance to balance the differential pressure between the front casing 4 and inner space 12 to avoid the air bubbles sucked into the front casing 4 from inner space 12. If the back vanes 51 generate negative pressure, the differential pressure will be more serious, then the seal channel 56 with the second sharp turn 565 and the first sharp turn 564 can offer extra flow resistance to avoid the air 24 be sucked into the front casing 4. The stator holes 544 directly connect to the bottom of the inner space 12, and the less air bubbles liquid 263 could be sucked in directly, and the stator holes 544 could offer more liquid with less air bubbles flowing in at first sharp turn 564. So the seal channel 56 could reduce the air bubbles flowing downward

Referring to FIG. 9(b), when the liquid level 29 is normal, and the pump discharge is high capacity, the shaft seal device 55 could offer extra flow resistance to balance the differential pressure between the inner space 12 and the front casing 4, to avoid the air bubbles be sucked into the front casing 4. On the contrary the pump discharge is high pressure, the shaft seal device 55 could offer extra flow resistance to balance the differential pressure between the inner space 12 and the front casing 4, and to reduce high-pressure liquid leak from the front casing 4 to the inner space 12 through the seal channel 56. Partly kinetic energy of the high-pressure liquid will loss at the inlet of the seal channel 562, the conical part 561, the first sharp turn 564, and the second sharp turn 565, then the outlet 563. Before changing the flow direction at the first turn 564, some of the liquid will be guided to discharge directly from the stator holes 544 to inner space 12, the rotation of the conical part 531 of the rotor 53 will increase the flow resistance. At outlet 563, as the liquid is only provided with very low kinetic energy, the liquid level of the free vortex 2 cannot be fluctuated in inner space 12. The leakage at flow direction 265 is tow but still causes the liquid level to rise, which will require the diffuser 10 in the pump column 1 to maintain the stability of the liquid level in the inner space 12.

Referring to FIG. 9(c), when the pump shuts down, the high-pressure liquid in the piping flushes back momentarily along the back-flush direction 271 from the discharge pipe 43, flows back to the front casing 4 and exits from the inlet port 44. Part of the high-pressure back-flush of the liquid 265 will also flush back and flow upward through the back vanes 51 and then the channel seal 56. Partly kinetic energy of the high-pressure back-flush of the liquid 265 will be loss at the inlet of the seal channel 562, the conical part 561, the first sharp turn 564, and the second sharp turn 565, then the outlet 563 of the seal channel 562. At the first sharp turn 564 where the high-pressure back-flush of the liquid 265 will be discharged directly to the inner space 12 along the direction 263, and two sharp turn will changes the momentum direction significantly. In addition, the kinetic energy of the back-flush liquid 265 will be absorbed by the conical part 561 also. At the end, residual of the back-flush liquid 265 will finally flow out of the outlet of the seal channel 563 and enter into the inner space 12. As the liquid is only provided with extremely low kinetic energy, the liquid splashing at the level cannot be formed at this time.

Referring to FIG. 10(a), it shows a schematic drawing of a diffuser blade 14, which is arranged with the plural diffuser holes 112 of the support column 1. Referring to FIG. 10(b), it shows a perspective drawing of a diffuser blade 16, which is arranged with the plural diffuser holes 17 of the support column 1.

Referring to FIG. 11, it shows a cross-sectional drawing of diffuser holes 15 only, which is arranged in circumference.

Conclude from the above, in accordance with the present invention, the pump includes the shaft seal device 55, the diffuser 10 in the pump column and the upper inner plate 83 of the support column. This low-cost and simple structure can effectively isolate the air bubbles from being sucked into the pump, maintain the stable liquid level in the inner space and prevent the liquid from flushing back momentarily to damage the V-type oil seal at the motor side when the pump shuts down.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional drawing of a conventional product.

FIG. 2 is a drawing of a tangential velocity of free vortex versus a shaft outer radius.

FIG. 3 is a cutaway drawing of a conventional product, a liquid level of a tank of which is the lowest.

FIG. 4 is a cutaway drawing of a conventional product, a liquid level of a tank of which is the highest.

FIG. 5 is a cutaway drawing of a conventional product which shuts down.

FIG. 6(a) is a cross-sectional drawing of an embedment of the present invention.

FIG. 6(b) is cross-sectional drawing of second embedment of the present invention.

FIG. 6(c) is a cross-sectional drawing of third embedment of the present invention.

FIG. 7(a) is a perspective drawing of a shaft seal device of the present invention.

FIG. 7(b) is a cross-section of a shaft seal device of the present invention.

FIG. 7(c) is a cross-section of a shaft seal device of the present invention.

FIG. 8 is a cross-sectional drawing of a shaft seal device assembled in vertical submerged pump of the present invention.

FIG. 9(a) is a schematic drawing of a low liquid level operation of the present invention.

FIG. 9(b) is a schematic drawing of a normal liquid level operation of the present invention.

FIG. 9(c) is a schematic drawing of a back-flush liquid of the present invention.

FIG. 10(a) is a schematic drawing of a diffuser blade of the present invention.

FIG. 10(b) is a perspective drawing of the diffuser blade of the present invention.

FIG. 10(c) is another cross-sectional drawing of a diffuser blade of the present invention.

FIG. 11 is a cross-sectional drawing of a diffuser hole of the present invention.

Claims

1. A vertical submerged pump for chemical application, the structural improvement includes the shaft seat device, the diffuser in the pump column and the upper inner plate of the support column, their features are as flows:

A shaft seal device has a rotor of N-type seal and a stator of N-type seal, the stator is provided with an outer cylindrical part of the stator and a plate part of the stator, the stator is installed in an inner surface of a pump casing by the plate part of the stator, the cylindrical stator is provided with two inner column surfaces of different radii and a conical part which is extended downward, the cylindrical rotor is provided with two outer column surfaces of different radii and a conical part which is extended upward, the rotor is installed on an impeller hub by an inner diameter of the rotor, after the pump is assembled, the rotor is located at a relative position to the stator, the inner column surfaces of the stator and the outer column surfaces of the rotor match each other to form a non-contact seal channel which having two sharp turns with a bending angle larger than 90°, and plural stator holes are located at the first sharp turn of the seal channel on the stator to connect to an inner space;

a diffuser in a support column is provided with plural diffuser holes and plural diffuser blades, the diffuser blades are arc shape and are installed on an inner wall of the support column, the plural diffuser blades are arranged alternately with the plural diffuser holes, the diffuser blades are arranged opposite to the flow direction of the liquid, and the flow channel is formed by the neighboring diffuser blades, an inlet of the flow channel is constituted by leading edges of the neighboring diffuser blades also, and the diffuser holes are located on an inner wall of the support column in the flow channel, the diffuser blade has a small incident angle in horizontal circumference at the leading edge, allowing the liquid to smoothly flow into the inlet of the diffuser in the support column without changing the flow direction significantly;

an upper inner plate of the support column which is installed in an interior side of the support column, and is located below an upper hole of the support column, with a center of which being provided with a hole to form a larger radial clearance with an outer diameter of a shaft sleeve.

2. The vertical submerged pump for chemical application according to claim 1, wherein, a diffuser in a support column which is provided with plural diffuser holes and plural diffuser blades, the diffuser blades are arc shape and are installed on an inner wall of the support column, the plural diffuser blades are arranged alternately with the plural diffuser holes, the leading edge of the diffuser blade of the diffuser in the support column is located above the diffuser holes, and the trailing edge of the diffuser blade is located below the next diffuser hole, the diffuser blades are arranged against to the flow direction of the liquid and kept an incident angle at leading edge of diffuser blade; the flow channels are formed by the neighboring diffuser blades, an inlet of the flow channel is constituted by leading edges of the neighboring diffuser blades also, an outlet of the flow channel is constituted by trailing edges of the neighboring diffuser blades and the diffuser holes are located on an inner wall of the support column in the flow channel.

3. The vertical submerged pump for chemical application according to claim 1, wherein the diffuser in the pump column is located in a middle or lower part of the support column.

4. The vertical submerged pump for chemical application according to claim 1, wherein, the diffuser in the support column is formed by plural diffuser holes only, which is arranged in a circumference of the support column, the diffuser holes have an oblique opening and form a small bevel angle against the circumference flow.

5. The vertical submerged pump for chemical application according to claim 1, wherein, a diffuser in a support column which is provided with plural longitude diffuser holes and plural longitude diffuser blades with span B, the diffuser blades are arc shape and installed on an inner wall of the support column, the plural diffuser blades are arranged alternately with the plural diffuser holes in circumference, the root of the diffuser blade is located at the side wall of the long diffuser hole, the diffuser blades are arranged opposite to the flow direction of the liquid, and the flow channel is formed by the diffuser blades, the inner wall of support column, and the longitudinal diffuser hole, the leading edge of the diffuser blade has an incident angle in circumference, the root of the diffuser blade has another angle as same as the oblique angle of diffuser hole in circumference.

6. The vertical submerged pump for chemical application according to claim 1, claim 2 and claim 5, wherein, the diffuser blade is a single circular arc structure or a complex circular arc structure.

7. The vertical submerged pump for chemical application according to claim 1, claim 2 and claim 5, wherein, an incident angle between the leading edge of the diffuser blade and a horizontal circumference is less than 45°.

8. The vertical submerged pump for chemical application according to claim 1, claim 2 and claim 5, wherein, the plural diffuser blades on the support column could be made in different ways, including each blade welded on or inserted in, or an integral cascade ring by plastic injection.

9. The vertical submerged pump for chemical application according to claim 1, claim 2 and claim 5, wherein, the plural diffuser blade on the support column could have the same span width or unequal span width.

10. The vertical submerged pump for chemical application according to claim 1, claim 2, claim 4 and claim 5, wherein, the plural diffuser holes on the support column could be longitude hole in parallel or incline hole in parallel.

11. The vertical submerged pump for chemical application according to claim 1, claim 2, claim 4 and claim 5, wherein, the diffuser in the support column is formed by plural diffuser holes only, the plural diffuser holes on the support column could be arranged in one row or multi-row around the support column.

12. The vertical submerged pump for chemical application according to claim 1 and claim 4, wherein, the diffuser in the support column is formed by plural diffuser holes and diffuser blades, or plural diffuser holes only, which are arranged in a circumference of the support column, the diffuser holes have an oblique opening and the oblique angle is less than 45°.

13. The vertical submerged pump for chemical application according to claim 1, claim 2, claim 4 and claim 5, wherein, the diffuser in the support column is formed by plural diffuser holes and diffuser blades, the plural diffuser holes and the diffuser blades on the support column could be arranged in one row or multi-row around the support column, and the multi-row could be staged for each row.

14. The vertical submerged pump for chemical application according to claim 1, wherein, the diffuser in the support column is formed by plural diffuser holes and diffuser blade, which are arranged in a circumference of the support column, the diffuser holes have an oblique opening and the oblique angle is less than 60°.

15. The vertical submerged pump for chemical application according to claim 1, wherein, the diffuser blades as same as the diffuser hole are longitude holes in parallel or incline holes in parallel.

16. A submerged vertical pump for chemical application, the structural improvement of the shaft seal device to offer extra flow resistance to separate liquid between the high pressure liquid from pump casing and low pressure liquid from inner space of support column, the shaft seal device is comprised of:

A shaft seal device has a rotor of N-type seal and a stator of N-type seal, the stator is provided with an outer cylindrical part and a plate part of the stator, the stator is installed in an inner surface of a pump casing by the plate part of the stator, the cylindrical stator is provided with two inner column surfaces of different radii and a conical part which is extended downward, the cylindrical rotor is provided with two outer column surfaces of different radii and a conical part which is extended upward, the rotor is installed on an impeller hub by an inner diameter of the rotor, after the pump is assembled, the rotor is located at a relative position to the stator, the inner column surfaces of the stator and the outer column surfaces of the rotor match each other to form a non-contact seal channel which has two sharp turns with a bending angle larger than 90°, and plural stator holes are located at the first sharp turn of the seal channel on the stator to connect to an inner space.

17. The vertical submerged pump for chemical application according to claim 16, wherein, plural rotor holes are located at the second sharp turn of the seal channel on the rotor to connect to an inner space.

18. The vertical submerged pump for chemical application according to claim 16, wherein, the stator is provided with an outer cylindrical part of the stator and a plate part of the stator, the outer cylindrical surface has a screw part, stator could be installed in inner surface of a pump casing by the screw, and till the plate part of the stator tied on the inner surface of pump front casing.

19. A submerged vertical pump for chemical application, the structural improvement of the shaft seal device to offer extra flow resistance to separate liquid between the high pressure liquid from pump casing and low pressure liquid from inner space of support column, the shaft seal device is comprised of:

A shaft seal device has a rotor of N-type seal and a stator of N-type seal, the stator is provided with an outer cylindrical part of the stator, the stator is installed in an inner surface of a pump casing, the cylindrical stator is provided with two inner column surfaces of different radii and a conical part which is extended downward, the cylindrical rotor is provided with two outer column surfaces of different radii and a conical part which is extended upward, the rotor is installed on an impeller hub by an inner diameter of the rotor after the pump being assembled, the rotor is located at a relative position to the stator, the inner column surfaces of the stator and the outer column surfaces of the rotor match each other to form a non-contact seal channel which have two sharp turns with a bending angle larger than 90°, and plural stator holes are located at the first sharp turn of the seal channel on the stator to connect to an inner space.

20. The vertical submerged pump for chemical application according to claim 19, wherein, the stator is provided with an outer cylindrical part of the stator, the out cylindrical surface has a screw part, stator could be tied in an inner surface of a pump casing by the screw.