Small flow, high head and high efficiency multi-stage volute centrifugal pump

Abstract

The present invention discloses a multi-stage volute centrifugal pump with small flow rate, high head and high efficiency. The pump comprises a main shaft, an inlet end, a pump housing, a left bearing box and a right bearing box; the left bearing box, a connecting frame, an inlet end, a pump housing and a right bearing box are sequentially connected to form a shell structure of the multi-stage volute centrifugal pump, a three-stage coaxially connected rotor structure assembly is installed in the pump housing, one end of the main shaft passes through the left bearing box, the connecting frame and the inlet end in sequence and is synchronously rotated and connected with the first-stage rotor structure assembly in the pump housing, a liquid inlet is provided at the inlet end, and the liquid enters the three-stage rotor structure assembly through the liquid inlet, and the third-stage rotor structure assembly extends out of the right bearing box to pump out the liquid. The present invention has the characteristics of small flow rate, high head and high efficiency, and is an ultra-low specific speed pump with small flow rate and high head. At the same time, compared with high-speed centrifugal pumps, the pump has high working efficiency and low speed, and the number of stages of the pump can be increased according to the actual requirements of the conveying medium, and is not limited to a three-stage pump.

Description

Technical Field

[0001] The invention relates to a small flow rate, high lift and high efficiency multi-stage volute centrifugal pump, in particular to a multi-stage high efficiency volute centrifugal pump used for fluid transportation in the fields of petrochemical industry, papermaking, food, etc. Background Art

[0002] In order to meet the demand for small flow and high head, high-speed centrifugal pumps, also known as partial flow pumps, are often used in actual production. They have low efficiency due to their low specific speed and are prone to unstable operation at small flow rates.

[0003] The volute centrifugal pump, also known as the rotary jet pump, is a single-stage, cantilevered pump with a small flow rate and high head. It is currently mainly used in the fields of petrochemicals, papermaking, and food to transport clean liquids or liquids containing solid particles. Since then, the volute centrifugal pump has been more widely used due to its simple structure, small size, stable operation, low speed, good anti-cavitation performance, good sealing performance, and its good reputation in these fields and strong subsequent development. The volute centrifugal pump has now become the infusion pump of the drilling flushing system in the automotive manufacturing industry, the feed pump of the carbon black production line, and has become the preferred equipment in the field of deep well waste treatment in chemical plants, and the standard equipment for high-pressure cleaning systems in food processing, manufacturing workshops, and papermaking industries.

[0004] In these practical engineering applications, this single-stage, cantilevered volute centrifugal pump has already possessed very outstanding performance. Its advantages of small flow, high head, and low specific speed are consistent with the characteristics of the high-speed centrifugal pump that needs to be improved. Summary of the invention

[0005] Under such technical background and in combination with the problems encountered in actual production, in view of the shortcomings of high-speed centrifugal pumps in efficiency and stability, in order to overcome the shortcomings of existing high-speed centrifugal pumps in the background technology, the present invention has made some technical improvements and optimizations on the basis of the volute centrifugal pump. The inventor has invented a small-flow, high-lift, and high-efficiency multi-stage volute centrifugal pump, which can be used for fluid transportation in the fields of petrochemical, papermaking, food, etc.

[0006] The technical solution adopted by the present invention is:

[0007] The present invention comprises a main shaft, an inlet end, a pump housing, a left bearing box and a right bearing box; the left bearing box, a connecting frame, an inlet end, a pump housing and a right bearing box are connected in sequence to form a shell structure of a multi-stage rotating casing centrifugal pump, a three-stage coaxially connected rotor structure assembly is arranged in the pump housing, one end of the main shaft passes through the left bearing box, the connecting frame and the inlet end in sequence and is connected to the first-stage rotor structure assembly in the pump housing for synchronous rotation, a liquid inlet is provided at the inlet end, liquid enters the three-stage rotor structure assembly through the liquid inlet, and the third-stage rotor structure assembly extends out of the right bearing box to pump out the liquid.

[0008] A liquid inlet is provided on a side wall of the inlet end, and an annular inner cavity is provided around the main shaft at the inlet end to communicate with the liquid inlet; each stage of the rotor structural assembly includes a centrifugal impeller, a rotor cavity shell and a collecting pipe, and a centrifugal impeller and a collecting pipe are installed in the inner cavity of the rotor cavity shell, the centrifugal impeller is located on the side of the rotor cavity shell cavity close to the upstream, the outer peripheral edge of the centrifugal impeller is fixedly connected to the inner circumferential surface of the rotor cavity shell, the collecting pipe is located on the side of the rotor cavity shell cavity close to the downstream, and the side of the rotor cavity shell cavity close to the downstream serves as the rotor cavity, and the fluid medium is driven to flow into the rotor cavity under the rotation of the impeller;

[0009] The collecting pipe includes an axis portion, a diameter portion and a bending portion. The axis portion and the main shaft are arranged coaxially, the diameter portion is arranged in a direction perpendicular to the main shaft, the inner end of the diameter portion is connected to the side of the middle portion of the axis portion to form an L shape, and the outer end of the diameter portion is vertically bent along the tangent of the circumference to form a bending portion. The tangential direction of the vertical bending of the bending portion of the collecting pipe is opposite to the tangential direction of the clockwise direction when the whole formed by the rotor chamber shell and the centrifugal impeller rotates around the main shaft and the axis portion of the collecting pipe; a through hollow channel is opened inside the axis portion, the diameter portion and the bending portion of the collecting pipe, one end of the hollow channel passes through one end of the axis portion away from the main shaft, the other end of the hollow channel is connected from the axis portion via the diameter portion to the bending portion, and passes through from the end of the bending portion to be connected with the inner cavity of the rotor chamber shell; the fluid in the rotor cavity flows in through the inlet of the hollow channel at the end of the bending portion of the collecting pipe, and flows out from the outlet at the end of the axis portion of the collecting pipe away from the main shaft.

[0010] The rotor cavity shell of the three-stage rotor structural assembly is coaxially fixedly connected, and horizontal through holes are opened in the centers of the two horizontal end faces; the horizontal through hole on the front end face of the rotor cavity shell of the first-stage rotor structural assembly is directly connected to the annular inner cavity, and the main shaft extends from the horizontal through hole on the front end face of the rotor cavity shell into the rotor cavity shell of the first-stage rotor structural assembly.

[0011] The front end of the shaft of the collector of the first-stage rotor structural assembly is rotatably connected to the main shaft end through a rolling bearing; the rear end of the shaft of the collector of the first and second-stage rotor structural assemblies extends from the horizontal through hole on the rear end surface of its own rotor cavity shell and then extends into the rotor cavity shell of the next-stage rotor structural assembly, and is coaxially connected with the front end of the shaft of the collector in the rotor cavity shell of the next-stage rotor structural assembly; the rear end of the shaft of the collector of the first and second-stage rotor structural assemblies is provided with a side wall through hole in the vertical direction, and the fluid in the collector flows into the rotor cavity shell of the next-stage rotor structural assembly through the side wall through hole; the rear end of the shaft of the collector of the third-stage rotor structural assembly extends out of its own rotor cavity shell and then passes through and extends out of the right bearing box, and the hollow pipe port at the rear end of the shaft of the collector of the third-stage rotor structural assembly serves as a liquid outlet; the rear end of the shaft of the collector of the third-stage rotor structural assembly is provided with a hollow shaft in the movable sleeve extending out of the rotor cavity shell and in the right bearing box, and the hollow shaft is connected to the rotor cavity shell of the third-stage rotor structural assembly through bolts.

[0012] The central inner hole of the centrifugal impeller of the first-stage rotor structural assembly is coaxially fixedly mounted on the main shaft, and there is a gap between the centrifugal impeller and the horizontal through hole wall of the front end surface of the rotor cavity shell of the first-stage rotor structural assembly, and the gap is connected to the annular inner cavity; the centrifugal impellers of the second and third-stage rotor structural assemblies are rotatably connected and mounted on the front ends of their respective collecting pipe shafts through water-lubricated bearing shafts; there is a circumferential gap between the rotor cavity shell of the three-stage rotor structural assembly and the inner circumferential surface of the pump housing, so that the rotor cavity shell of the three-stage rotor structural assembly and the respective impellers form a whole and rotate around the main shaft and the respective collecting pipe shafts.

[0013] One end of the main shaft is supported by a sliding bearing and is sleeved in a left bearing box, which is filled with lubricating oil. The other end of the main shaft is coaxially connected to the output shaft of the motor through a coupling. The motor drives the main shaft to rotate under the support of the sliding bearing and is self-lubricated by the lubricating oil in the left bearing box.

[0014] The centrifugal impeller is composed of a plurality of blades arranged at intervals along the circumference, and gaps for fluid to pass through are formed between adjacent blades.

[0015] The hollow shaft is sleeved on the collecting pipe of the third-stage rotating structure component. The inner ring of the hollow shaft is installed with a sliding bearing and a thrust bearing. The hollow shaft is movably sleeved with the collecting pipe of the third-stage rotating structure component through the sliding bearing and the thrust bearing. The hollow shaft is fixedly connected to the rotor cavity shell of the third-stage rotating structure component at one end close to the main shaft by bolts.

[0016] When the main shaft passes through the inlet end, a felt ring is installed between the main shaft and the inner wall of the inlet end for sealing.

[0017] The rotor cavity shell and the centrifugal impeller in each stage of the rotating structural assembly are cast in one piece.

[0018] The multi-stage volute centrifugal pump of the present invention is used in fluid transportation in the fields of petrochemical industry, papermaking, food, etc.

[0019] The fluid medium of the present invention flows in through the liquid inlet, and the rotation of the main shaft and the hollow shaft drives the three rotor chamber shells of the entire pump and the three centrifugal impellers of each to rotate at high speed. Under the action of centrifugal force, the fluid enters the first-stage rotor chamber that rotates synchronously at high speed from the L-shaped flow channel and the annular flow channel, so that the liquid around the rotor chamber has a very high pressure. The high-speed liquid flows into the static manifold. The manifold is equivalent to the water pressure chamber of an ordinary centrifugal pump, has a pressure expansion effect, converts speed energy into pressure energy, and then transports the output high-pressure liquid to the second-stage rotor chamber through the manifold. Finally, the high-pressure liquid is output from the manifold of the rotor chamber of the third-stage pump.

[0020] The multi-stage volute centrifugal pump structure of the present invention has the characteristics of small flow, high head and high efficiency. It is an ultra-low specific speed pump with small flow and high head. At the same time, compared with high-speed centrifugal pumps, the pump has high working efficiency and low speed. In the patent of the present invention, the multi-stage volute centrifugal pump is only exemplified by a three-stage pump. According to the present invention, the multi-stage pump can be disassembled into a single stage or two stages, and the number of pump stages can be increased according to the actual requirements of the conveying medium, and is not limited to a three-stage pump.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] Aiming at the technical problems of low efficiency and unstable operation at low flow rate due to low specific speed, the present invention improves the efficiency and stability of the centrifugal pump based on the casing volute pump while meeting the requirements of low flow rate and high head. In the field of low flow rate and high head, i.e. low specific speed, high-speed pumps do not need to be multi-staged. The present invention optimizes and adopts a multi-stage casing volute centrifugal pump to meet the requirements of high head.

[0023] The present invention adopts a series combination of the rotor chamber of a common volute centrifugal pump and the manifold and impeller therein to form a multi-stage volute centrifugal pump, and its head flow can be adjusted according to production needs. 3 / h, and an ultra-low specific speed pump with a head of more than 1000 meters, if a conventional high-speed centrifugal pump (generally designed with a speed of more than 10,000 rpm) is used, the efficiency is basically only about 20-30%. However, under the same working conditions, the efficiency of the present invention can reach more than 40-50%, and the speed is relatively low (about 5000 rpm). The multi-stage volute centrifugal pump is equipped with sliding bearings at both ends and a thrust bearing at the right end, which can ensure the stability of the entire rotating system at ultra-low specific speed.

[0024] The present invention is modified on the basis of a volute centrifugal pump, and innovatively adopts a multi-stage series connection method to increase its head. Similarly, pumps with low specific speed and small flow rate will have a certain impact on stability. Sliding bearings are installed at both ends of the multi-stage volute centrifugal pump and a thrust bearing is installed at the right end, which improves its rotation accuracy and stability and gives it more excellent performance.

[0025] Compared with the traditional high-speed centrifugal pump, the device of the present invention improves its efficiency and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a cross-sectional view of the present invention.

[0027] In the figure: 1, motor, 2, coupling, 3, main shaft, 4, left bearing box, 5, sliding bearing, 6, connecting frame, 7, mechanical seal, 8, felt ring, 9, inlet end, 10, liquid inlet, 11, annular inner cavity, 12, rolling bearing, 13, centrifugal impeller, 14, collecting pipe, 15, rotor cavity, 16, side wall through hole, 17, water-lubricated bearing, 18, rotor cavity shell, 19, pump housing, 20, hollow shaft, 21, sliding bearing, 22, thrust bearing, 23, right bearing box, 24, liquid outlet. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0029] like Figure 1 As shown, the specific implementation includes a main shaft 3, an inlet end 9, a pump housing 19, a left bearing box 4 and a right bearing box 23; the left bearing box 4, the connecting frame 6, the inlet end 9, the pump housing 19 and the right bearing box 23 are sequentially connected to form the shell structure of a multi-stage volute centrifugal pump, and the pump housing 19 is equipped with a three-stage coaxially connected rotor structure assembly, and the three-stage rotor structure assembly is coaxially arranged. One end of the main shaft 3 passes through the left bearing box 4, the connecting frame 6, and the inlet end 9 in sequence and is synchronously rotated and connected with the first-stage rotor structure assembly in the pump housing 19. The inlet end 9 is provided with a liquid inlet 10, and the liquid enters the three-stage rotor structure assembly through the liquid inlet 10, and the third-stage rotor structure assembly extends out of the right bearing box 23 to pump out the liquid. When the main shaft 3 passes through the inlet end 9, a felt ring 8 is installed between the main shaft 3 and the inner wall of the inlet end 9 for sealing.

[0030] Each stage of the rotor structural assembly includes a centrifugal impeller 13 , a rotor cavity shell 18 and a collecting pipe 14 . The centrifugal impeller 13 and the collecting pipe 14 are installed in the inner cavity of the rotor cavity shell 18 .

[0031] The centrifugal impeller 13 is located on the upstream side of the inner cavity of the rotor cavity shell 18. The outer peripheral edge of the centrifugal impeller 13 is fixedly connected to the inner circumference of the rotor cavity shell 18 through a plurality of support rods arranged at intervals along the circumference. The impeller 13 is composed of a plurality of blades arranged at intervals along the circumference, and gaps for fluid to pass through are formed between adjacent blades. The centrifugal impeller 13 is closer to the upstream inlet than the manifold 14, and the downstream side of the inner cavity of the rotor cavity shell 18 is used as the rotor cavity 15, that is, Figure 1 The inner cavity of the rotor cavity shell 18 at the right part of the centrifugal impeller 13 shown in the figure serves as the rotor cavity 15 , and the fluid medium is driven to flow into the rotor cavity 15 by the rotation of the impeller 14 .

[0032] The collecting pipe 14 is located in the inner cavity of the rotor cavity shell 18 near the downstream side. The collecting pipe 14 includes a shaft portion, a diameter portion and a bending portion. The shaft portion and the main shaft 3 are arranged coaxially, the diameter portion is arranged in a direction perpendicular to the main shaft 3, the diameter portion is arranged along a side perpendicular to the shaft portion and extending in a radial direction from the end of the shaft portion, the inner end of the diameter portion is connected to the side of the middle of the shaft portion to form an L shape, the diameter portion is entirely located in the rotor cavity 15, and the outer end of the diameter portion is bent vertically along the tangent of the circumference to form a bending portion, and the tangential direction of the vertical bending of the bending portion of the collecting pipe 14 is the same as the integral body formed by the rotor cavity shell 18 and the impeller 13 around the main shaft 3 and the shaft portion of the collecting pipe 14. When rotating, the tangential direction is opposite to the clockwise direction; a through hollow channel is opened inside the shaft, diameter and bend of the collecting pipe 14, one end of the hollow channel passes through the end of the shaft away from the main shaft 3, and the other end of the hollow channel is connected to the bend from the shaft via the diameter, and passes through from the end of the bend to be connected with the inner cavity of the rotor cavity shell 18, and both ends of the hollow channel pass through the end faces of the shaft and the bend of the collecting pipe 14 respectively; the fluid in the rotor cavity shell 18 / rotor cavity 15 flows in through the inlet of the hollow channel at the end of the bend of the collecting pipe 14, and flows out from the outlet at the end of the shaft of the collecting pipe 14 away from the main shaft 3.

[0033] There is also an inlet end 9 between the connecting frame 6 and the pump housing 14, and a liquid inlet 10 is provided on one side wall of the inlet end 9. An annular inner cavity 11 is provided around the inlet end 9 where the main shaft 3 passes, and the annular inner cavity 11 is connected to the liquid inlet 10; Figure 1 As shown, the liquid inlet 10 and the annular inner cavity 11 are connected to form an L-shaped liquid inlet flow channel, and there is a certain gap between the L-shaped liquid inlet flow channel shaft and the through hole wall of the rotor cavity shell 18 of the first-stage rotating structural component and the main shaft 3 in the radial direction. The L-shaped flow channel of the inlet liquid port serves as a flow channel for the fluid medium and a vertical flow channel and the annular inner cavity 11, and the surface is smoothed and anti-corrosion treated.

[0034] In the present invention, the upstream end face of the rotor cavity shell 18 close to the main shaft 3 is the front end face of the rotor cavity shell 18 , and the downstream end face of the rotor cavity shell 18 away from the main shaft 3 is the rear end face of the rotor cavity shell 18 .

[0035] The rotor cavity shell 18 of the three-stage rotor structural assembly is coaxially fixedly connected, and the centers of the two horizontal end faces are provided with coaxial horizontal through holes. The horizontal through holes of the rotor cavity shells 18 of the adjacent stage rotor structural assemblies are directly coaxially connected for the collector 14 to pass through; the horizontal through hole on the front end face of the rotor cavity shell 18 of the first stage rotor structural assembly is directly connected to the annular inner cavity 11, and the main shaft 3 extends into the rotor cavity shell 18 of the first stage rotor structural assembly from the horizontal through hole on the front end face of the rotor cavity shell 18; the hole end faces of the left end through holes of the rotor cavity shell 18 of the first stage rotating structural assembly are respectively rotationally matched with the end faces of the annular inner cavity through packing seals, and the rotor cavity shells 18 of the first, second and third stage rotating structural assemblies are connected as a whole by bolts and rotate together.

[0036] The front end of the shaft of the collector 14 of the first-stage rotor structural assembly is rotatably connected to the end of the main shaft 3 through a rolling bearing 12, and a rolling bearing 12 is installed at the joint. The rolling bearing 12 is installed at the joint and has a shoulder for positioning. While ensuring the rotation of the main shaft 3, the clamping of the collector 14 is ensured to keep it fixed in the axial direction, making the whole more compact. The rear end of the shaft of the collector 14 of the first and second-stage rotor structural assemblies extends from the horizontal through hole on the rear end surface of its own rotor cavity shell 18 and then extends into the rotor cavity shell 18 of the next-stage rotor structural assembly, and is coaxially connected with the front end of the shaft of the collector 14 in the rotor cavity shell 18 of the next-stage rotor structural assembly; in this way, the shaft of the collector 14 and the main shaft 3 in the first-stage rotor structural assembly extend into the rotor cavity shell 18 of the first-stage rotor structural assembly from both sides of the rotor cavity shell 18.

[0037] The rear end of the shaft of the manifold 14 of the first and second stage rotor structural components has a side wall through hole 16 in the vertical direction, and the fluid in the manifold 14 flows into the rotor cavity shell 18 of the next stage rotor structural component through the side wall through hole 16; the rear end of the shaft of the manifold 14 of the third stage rotor structural component extends out of its own rotor cavity shell 18 and then passes through and extends out of the right bearing box 23, and the hollow pipe port at the rear end of the shaft of the manifold 14 of the third stage rotor structural component serves as the liquid outlet 24; the rear end of the shaft of the manifold 14 is directly connected to the liquid outlet 24 as a whole. In this way, the liquid outlet 24 is directly connected to the shaft of the manifold 14 in the rotor cavity shell 18 of the third stage rotating structural component as a whole, and the hollow pipe of the manifold 14 serves as an outflow channel.

[0038] The rear end of the shaft of the collecting pipe 14 of the third-stage rotor structural assembly extends out of the rotor cavity shell 18 and is inside the right bearing box 23. A hollow shaft 20 is movably mounted on the hollow shaft 20 through a sliding bearing 21 and a thrust bearing 22. The sliding bearing 21 and the thrust bearing 22 are installed on the hollow shaft 20, and the hollow shaft 20 is connected to the rotor cavity shell 18 of the third-stage rotor structural assembly through bolts.

[0039] The centrifugal impeller 13 of the first-stage rotor structural assembly is coaxially fixedly mounted on the main shaft 3 through the central inner hole of the round head flat key, which is convenient for the disassembly and installation of the main shaft; there is a gap between the centrifugal impeller 13 and the horizontal through hole wall of the front end surface of the rotor cavity shell 18 of the first-stage rotor structural assembly, and the gap is connected to the annular inner cavity 11; the centrifugal impellers 13 of the second and third-stage rotor structural assemblies are rotatably connected and mounted on the front ends of the shafts of their respective collecting pipes 14 through water-lubricated bearing shafts 17.

[0040] The rotor cavity shell 18 of the three-stage rotor structural assembly is cast as a whole and installed in the pump housing 19, and there is a circumferential gap between the rotor cavity shell 18 and the inner circumferential surface of the pump housing 19, so that the rotor cavity shell 18 of the three-stage rotor structural assembly and the respective centrifugal impellers 13 form a whole and rotate around the main shaft 3 and the shaft of the respective collecting pipe 14.

[0041] One end of the main shaft 3 is supported by a sliding bearing 5 and is sleeved in the left bearing box 4. The left bearing box 4 is filled with lubricating oil. The other end of the main shaft 3 is coaxially connected to the output shaft of the motor 1 through the coupling 2. The motor 1 drives the main shaft 3 to rotate under the support of the sliding bearing 5, and self-lubricates through the lubricating oil in the left bearing box 4. The lubricating oil allows the main shaft 3 to be well lubricated and dissipated during rotation, and at the same time allows the bearing to better support and rotate the main shaft 3. An oil injection hole is opened on the top of the bearing box, and an oil plug is installed in the oil injection hole, which can make it more convenient to add and monitor the lubricating oil.

[0042] There is also a connecting frame 6 equipped with a mechanical seal device between the left bearing box 4 and the inlet end 9. The mechanical seal is arranged radially perpendicular to the main shaft 3, which can prevent fluid leakage while ensuring the rotation of the main shaft 3. Since the pressure between the main shaft 3 and the pump housing 19 is not high, the felt ring 8 is selected for sealing instead of the mechanical seal selected for the general rotating shell centrifugal pump, which prevents the leakage of the running fluid and makes the sealing reliability very good.

[0043] The hollow shaft 20 is sleeved on the collecting pipe 14 of the third-stage rotating structure assembly, and the inner ring of the hollow shaft 20 is installed with a sliding bearing 21 and a thrust bearing 22. The hollow shaft 20 is movably sleeved with the collecting pipe 14 of the third-stage rotating structure assembly through the sliding bearing 21 and the thrust bearing 22. The hollow shaft 20 is fixedly connected to the rotor cavity shell 18 of the third-stage rotating structure assembly at one end close to the main shaft 3 by bolts; under the rotation of the main shaft 3, the hollow shaft 20 is driven to rotate together with the third-stage rotor cavity shell 18 and its centrifugal impeller 13, and is self-lubricated by the lubricating oil in the right bearing box 23.

[0044] The axes of the centrifugal impellers 13 in the rotor cavity 15 of the first-stage rotating structural assembly are coaxially connected by round head flat keys.

[0045] The rotor chamber shell 19 and the centrifugal impeller 13 in each stage of the rotating structural assembly are integrally cast. The main shaft 3 and the centrifugal impeller 13 in the rotor chamber 15 of the first stage rotating structural assembly are connected together by a key, and the centrifugal impeller 13 and the entire rotor chamber shell 18 are integral, which makes the former easier and more convenient to install and disassemble. The traditional rotating shell centrifugal pump is a rotor chamber shell and a main shaft connected together by screws, and the impeller and the shell are also integral, which solves the problem of inconvenient disassembly and installation.

[0046] The flow channel between the main shaft 3 and the inlet end 9 and the rotor chamber shell 18 is sealed by means of packing seals to prevent leakage of the fluid medium; the gap between the collecting pipe 14 and the centrifugal impeller 13 of the second-stage rotating structural assembly is filled with water flow, and is connected by a water-lubricated bearing 17, which can allow the bearing to rotate better on the one hand, and on the other hand, can provide a better seal between the collecting pipe 14 and the rotor chamber 15.

[0047] There is a gap between the centrifugal impeller 13 and the front end face of the rotor chamber shell 18 near one end of the main shaft 3 and serves as an annular flow channel. There is a gap between the hole wall of the left end through hole of the rotor chamber shell 18 of the first-stage rotating structural component and the through hole of the L-shaped flow channel shaft portion of the inlet end face and the main shaft 3 and serves as an annular inner cavity 11. The rear end face of the centrifugal impeller 13 and the inner cavity part of the rotor chamber shell 8 serve as a rotor cavity 15. The outer ring part of the annular flow channel corresponding to the left end face of the centrifugal impeller 13 is connected to the rotor cavity 15 through the gap between the peripheral edge of the centrifugal impeller 13 and the inner circumferential surface of the rotor chamber shell 8. The inner ring part of the annular flow channel corresponding to the left end face of the centrifugal impeller 13 is connected to the hole wall of the left end through hole of the rotor chamber shell 18 and the annular inner cavity 11 corresponding to the inlet end face L-shaped flow channel shaft portion and the vertical flow channel of the L-shaped flow channel neck; the fluid flowing into the vertical flow channel flows into the first-stage rotor cavity 15 through the annular inner cavity 11 and the annular flow channel.

[0048] The present invention realizes the multi-stage volute centrifugal pump through the combined action of the centrifugal impellers 13 and the collecting pipes 14 in the multiple rotor chambers 15, thereby increasing the head. By installing the sliding bearing 5 at one end of the main shaft 3 and installing the sliding bearing 21 and the thrust bearing 22 at one end of the hollow shaft 20, the left and right ends can be supported and fixed, so that the original cantilever type is changed to a fixed type at both ends, thereby realizing low vibration of the multi-stage volute centrifugal pump.

[0049] In specific implementation, Figure 1 As shown, the working process of the present invention is as follows:

[0050] First, start the motor 1. The output shaft of the motor 1 is connected to the main shaft 3 through the coupling 2. The other end of the main shaft 3 extends into the left bearing box 6. The left bearing box 6 is equipped with a sliding bearing 5 for fitting the main shaft 3. The oil plug installed in the left bearing box 6 can be used to reasonably add lubricating oil to the sliding bearing 5 of the left bearing box 6. In this way, the main shaft 3 can achieve better rotation and self-lubrication under the support of the sliding bearing 5.

[0051] The operation of the motor 1 drives the main shaft 3 to rotate. Before the main shaft 3 enters the inlet end 9, it must first pass through the connecting frame 6. A mechanical seal 7 is installed in the connecting frame 6 to ensure the sealing of the main shaft 3 during rotation. After entering the inlet end 9, the main shaft 3 passes through the annular inner cavity 11 and the annular flow channel and enters the rotor chamber shell 18 of the first-stage rotating structural component. The first-stage centrifugal impeller 13 is connected to the main shaft 3 through a round head flat key. The centrifugal impeller 13 and the rotor chamber shell 18 are cast as one piece and fixedly connected to the inner circumferential surface of the rotor chamber shell 18 through a plurality of support rods arranged at intervals along the circumference. The rotor chamber shells 18 of the first-stage, second-stage and third-stage rotating structural components are connected together by bolts. A hollow shaft 20 is sleeved on the outer periphery of the shaft of the collector 14 of the third-stage rotating structural component. The hollow shaft 20 is connected to the rotor chamber shell 18 of the third-stage rotating structural component by bolts, so that the main shaft 3, the third-stage rotor chamber shell 18 and its impeller 13 and the hollow shaft 20 form a synchronously rotating whole.

[0052] During the rotation of the first, second and third stage rotor chambers 15 and the centrifugal impeller 13, the fluid medium enters the rotor chamber shell 18 of the first stage rotating structural component through the liquid inlet 10 through the L-shaped flow channel and the annular flow channel. The internal centrifugal impeller 13 and the rotor chamber shell 18 rotate to generate centrifugal force, driving the fluid medium in the rotor chamber 15 to be thrown from the center of the rotor chamber 15 to the outer edge of the rotor chamber 15, increasing the speed, having a certain pressure, and having very high speed energy, and gradually increasing the pressure through the first, second and third stage centrifugal impellers 13, thereby improving the maximum head of the multi-stage volute centrifugal pump.

[0053] Since the tangential direction of the bend at the end of the diameter of the manifold 14 is opposite to the rotation direction of the two centrifugal impellers 13 and the rotor chamber shell 18, the rotating fluid at the outer edge of the rotor chamber 15 enters the hollow channel inlet at the end face of the bend of the manifold 14, and then flows out from the hollow channel outlet at the end face of the shaft of the manifold 14. The fluid coming out of the manifold 14 of the first-stage rotating structural assembly flows out from the side wall through hole 16 at the end of its shaft, enters the rotor chamber 15 of the second-stage rotating structural assembly, and finally flows out from the manifold 14 in the rotor chamber 15 of the third-stage rotating structural assembly. The manifold 14 here is directly connected to the liquid outlet 24 as a whole.

[0054] Finally, due to the high-speed rotation of the fluid medium in the rotor cavity 15 and the high-speed rotation of the rotor cavity shell 18 itself, the entire rotor cavity shell 18 has very high kinetic energy. A three-stage coaxially connected rotor structure component is also installed here, which will inevitably make the vibration of the entire device more intense. Therefore, sliding bearings 5 ​​and 21 are respectively installed on a section of the main shaft 3 and one end of the hollow shaft 20 to play the role of supporting both ends. At the same time, a thrust bearing 22 is also installed at one end of the hollow shaft 20 to effectively withstand the thrust generated during rotation, effectively prevent the violent vibration of the rotor cavity shell 18, and effectively solve the vibration and noise problem of ultra-low specific speed of the multi-stage rotating shell centrifugal pump.

[0055] It can be seen from this implementation that the multi-stage volute centrifugal pump designed in the present invention improves the efficiency shortcomings of previous high-speed centrifugal pumps and makes reasonable optimizations based on its own structural characteristics. The sliding bearings supported at both ends and the axially stable thrust bearings improve the stability of the multi-stage volute centrifugal pump at ultra-low specific speeds and extend its service life.

Claims

1. A small flow, high head and high efficiency multi-stage volute centrifugal pump, characterized by: The invention comprises a main shaft (3), an inlet end (9), a pump housing (19), a left bearing box (4) and a right bearing box (23); the left bearing box (4), a connecting frame (6), an inlet end (9), a pump housing (19) and a right bearing box (23) are connected in sequence to form a shell structure of a multi-stage rotating casing centrifugal pump; a three-stage coaxially connected rotor structure assembly is installed in the pump housing (19); one end of the main shaft (3) passes through the left bearing box (4), the connecting frame (6) and the inlet end (9) in sequence and is connected to the first-stage rotor structure assembly in the pump housing (19) for synchronous rotation; a liquid inlet (10) is provided at the inlet end (9); liquid enters the three-stage rotor structure assembly through the liquid inlet (10); the third-stage rotor structure assembly extends out of the right bearing box (23) to pump out the liquid; A liquid inlet (10) is provided on a side wall of one side of the inlet end (9); an annular inner cavity (11) is provided on the inlet end (9) around the main shaft (3) and is communicated with the liquid inlet (10); each stage of the rotor structural assembly comprises a centrifugal impeller (13), a rotor cavity shell (18) and a collecting pipe (14); the centrifugal impeller (13) and the collecting pipe (14) are installed in the inner cavity of the rotor cavity shell (18); the centrifugal impeller (13) is located in the inner cavity of the rotor cavity shell (18) on the side close to the upstream; the outer peripheral edge of the centrifugal impeller (13) is fixedly connected to the inner circumferential surface of the rotor cavity shell (18); the collecting pipe (14) is located in the inner cavity of the rotor cavity shell (18) on the side close to the downstream; the inner cavity of the rotor cavity shell (18) on the side close to the downstream serves as a rotor cavity (15); the fluid medium is driven to flow into the rotor cavity (15) by the rotation of the centrifugal impeller (13); The collecting pipe (14) comprises an axial portion, a diameter portion and a bending portion. The axial portion and the main shaft (3) are arranged coaxially. The diameter portion is arranged in a direction perpendicular to the main shaft (3). The inner end of the diameter portion is connected to the side surface of the middle portion of the axial portion to form an L shape. The outer end of the diameter portion is vertically bent along the tangent direction of the circumference to form a bending portion. The tangential direction of the vertical bending of the bending portion of the collecting pipe (14) is opposite to the tangential direction of the whole formed by the rotor cavity shell (18) and the centrifugal impeller (13) when rotating around the main shaft (3) and the axial portion of the collecting pipe (14). A through hollow channel is provided inside the shaft, the diameter and the bend of the flow tube (14); one end of the hollow channel passes through the shaft end away from the main shaft (3); the other end of the hollow channel passes through the shaft end via the diameter to the bend, and passes through the end of the bend to communicate with the inner cavity of the rotor cavity shell (18); the fluid in the rotor cavity (15) flows in through the inlet of the hollow channel at the end of the bend of the flow collector (14) and flows out from the outlet at the shaft end away from the main shaft (3); The rotor cavity shells (18) of the three-stage rotor structural assembly are coaxially fixedly connected, and the centers of both horizontal end surfaces are provided with horizontal through holes; the horizontal through hole on the front end surface of the rotor cavity shell (18) of the first-stage rotor structural assembly is directly connected to the annular inner cavity (11), and the main shaft (3) extends from the horizontal through hole on the front end surface of the rotor cavity shell (18) into the rotor cavity shell (18) of the first-stage rotor structural assembly; The front end of the shaft of the collector (14) of the first-stage rotor structural assembly is rotatably connected to the end of the main shaft (3) through a rolling bearing (12); the rear ends of the shafts of the collectors (14) of the first and second-stage rotor structural assemblies extend from the horizontal through holes on the rear end surfaces of their own rotor cavity shells (18) and then extend into the rotor cavity shell (18) of the next-stage rotor structural assembly, and are coaxially connected to the front ends of the shafts of the collectors (14) in the rotor cavity shell (18) of the next-stage rotor structural assembly; The rear end of the shaft of the collecting pipe (14) of the first and second stage rotor structural assemblies is provided with a side wall through hole (16) in the vertical direction, and the fluid in the collecting pipe (14) flows into the rotor cavity shell (18) of the next stage rotor structural assembly through the side wall through hole (16); the rear end of the shaft of the collecting pipe (14) of the third stage rotor structural assembly extends out of its own rotor cavity shell (18) and then extends out of the right bearing box (23), and the hollow pipe port at the rear end of the shaft of the collecting pipe (14) of the third stage rotor structural assembly serves as a liquid outlet (24); the rear end of the shaft of the collecting pipe (14) of the third stage rotor structural assembly is provided with a hollow shaft (20) in the part of the movable sleeve extending out of the rotor cavity shell (18) and in the right bearing box (23), and the hollow shaft (20) is connected to the rotor cavity shell (18) of the third stage rotor structural assembly by bolts; The central inner hole of the centrifugal impeller (13) of the first-stage rotor structural assembly is coaxially fixedly mounted on the main shaft (3), and a gap is provided between the centrifugal impeller (13) and the horizontal through hole wall of the front end surface of the rotor cavity shell (18) of the first-stage rotor structural assembly, and the gap is connected to the annular inner cavity (11); the centrifugal impellers (13) of the second and third-stage rotor structural assemblies are rotatably mounted on the front ends of the shafts of their respective manifolds (14) through water-lubricated bearing shafts (17); a circumferential gap is provided between the rotor cavity shell (18) of the third-stage rotor structural assembly and the inner circumferential surface of the pump housing (19), so that the rotor cavity shell (18) of the third-stage rotor structural assembly and the respective impellers (13) form an integral body and rotate around the main shaft (3) and the shafts of their respective manifolds (14); One end of the main shaft (3) is supported by a first sliding bearing (5) and sleeved in a left bearing box (4). The left bearing box (4) is filled with lubricating oil. The other end of the main shaft (3) is coaxially connected to the output shaft of the motor (1) via a coupling (2). The motor (1) drives the main shaft (3) to rotate under the support of the first sliding bearing (5) and is self-lubricated by the lubricating oil in the left bearing box (4). The hollow shaft (20) is sleeved on the collecting pipe (14) of the third-stage rotating structure component. The inner ring of the hollow shaft (20) is installed with a second sliding bearing (21) and a thrust bearing (22). The hollow shaft (20) is movably sleeved with the collecting pipe (14) of the third-stage rotating structure component through the second sliding bearing (21) and the thrust bearing (22). The hollow shaft (20) is fixedly connected to the rotor chamber shell (18) of the third-stage rotating structure component at one end close to the main shaft (3) by bolts.

2. According to claim 1, a small flow, high head and high efficiency multi-stage volute centrifugal pump is characterized by: The centrifugal impeller (13) is composed of a plurality of blades arranged at intervals along the circumference, with gaps for fluid to pass through formed between adjacent blades.

3. The low-flow, high-lift, high-efficiency multi-stage volute centrifugal pump according to claim 1, characterized in that: When the main shaft (3) passes through the inlet end (9), a felt ring (8) is installed between the main shaft (3) and the inner wall of the inlet end (9) for sealing.

4. The low-flow, high-lift, high-efficiency multi-stage volute centrifugal pump according to claim 1, characterized in that: The rotor chamber shell (18) and the centrifugal impeller (13) in each stage of the rotating structural assembly are cast in one piece.

5. The use of the multi-stage volute centrifugal pump according to any one of claims 1 to 4, characterized in that: Used in fluid transportation in petrochemical, papermaking or food industries.

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