CN203742973U - Closed testing device for net positive suction head of submerged pumps - Google Patents

Abstract

The utility model belongs to the field of fluid machinery, in particular to a water-filled submersible pump and a well-used submersible pump NPSH closed-type test device. The test device consists of cavitation tank, inlet valve, heterocentric diffusion pipe, suction pipe, submersible pump, thermometer, inlet pressure gauge, transition pipe, sealing joint 1, speed measuring instrument, outlet pressure gauge, drain pipe, outlet pressure measuring tube, sealing Joint 2, upstream straight pipe section of flowmeter, inlet pressure measuring pipe, speed sensor, flowmeter, straight pipe section downstream of flowmeter, flow regulating valve, water injection valve, vacuum pump, drain valve, exhaust pipe, clapboard, liquid level gauge, air extraction Valve, exhaust valve composition. Thermometer, inlet pressure gauge, outlet pressure gauge, speed sensor and speed measuring instrument and flow meter are used to measure the key parameters of submersible pump NPSH. The beneficial effect of the utility model is that the critical NPSH of the submersible pump under different flow rates can be measured through the closed-type NPSH test device of the submersible pump, and the problem that the cavitation performance test of the submersible pump cannot be carried out can be solved.

Description

Submersible pump NPSH closed test device

technical field

The invention belongs to the field of fluid machinery, and relates to a hydraulic performance test of a submersible pump, in particular to a closed test device capable of measuring the NPSH of a water-filled submersible pump and a well submersible pump.

Background technique

A submersible pump is a general-purpose machine widely used in industry, agriculture, and various engineering fields. Its structure is that the submersible motor and the water pump share a shaft. Unlike general land water pumps, the submersible pump has no suction pipe.

The hydraulic performance index of the pump usually includes flow, head, shaft power, efficiency and NPSH, and NPSH is an indirect measurement, which must be calculated from the data of pump inlet pressure head, vaporization pressure head and other data. A large amount of data proves that cavitation damage is the direct culprit of water pump failure. Like other water pumps, submersible pumps often fail due to cavitation damage caused by submerged depth and high flow conditions. But so far, all submersible pump products and standards have failed to provide NPSH indicators.

The existing standard GB/T3216-2005 "Grade 1 and 2 of hydraulic performance acceptance test of rotary power pump" provides the hydraulic performance test method of general land centrifugal pump, mixed flow pump and axial flow pump, which is a general standard and can guide the The performance parameters (such as flow rate, head, shaft power, efficiency and NPSH) of water pumps with suction pipes are measured and tested. Since the submersible pump has no suction pipe, the total suction head cannot be measured, and the standard does not provide a specific method for measuring the NPSH of the submersible pump. Another standard GB/T12785-2002 "Test Methods for Submersible Electric Pumps" also does not provide a test method for cavitation performance of submersible pumps, and no public reports have been found in other documents.

Contents of the invention

The purpose of the present invention is to provide a closed test device capable of measuring the NPSH of a submersible pump, so as to provide a powerful test verification guarantee for the formulation of submersible pump product standards.

The technical scheme adopted by the present invention to solve its technical problems is: the submersible pump NPSH closed-type test device consists of a cavitation tank, an inlet valve, a different center diffusion pipe, a suction pipe, a submersible pump, a thermometer, an inlet pressure gauge, a transition pipe, Sealing joint 1, speed measuring instrument, outlet pressure gauge, drain pipe, outlet pressure measuring pipe, sealing joint 2, upstream straight pipe section of flowmeter, inlet pressure measuring pipe, speed sensor, flowmeter, downstream straight pipe section of flowmeter, flow regulating valve , water injection valve, vacuum pump, drain valve, exhaust pipe, partition, liquid level gauge, exhaust valve, and exhaust valve form a closed water circulation loop, as shown in Figure 1. One end of the inlet valve is flanged to the outlet of the cavitation tank, and the other end is flanged to the heterocentric diffusion pipe. The diffusion end of the heterocentric diffusion pipe is welded to one end of the suction pipe, and the other end of the suction pipe is connected to one end of the inlet pressure measuring pipe. It is connected by flange, the other end of the inlet pressure measuring pipe is connected with the end of the transition pipe by flange, the outlet flange of the submersible pump is connected with the large flange of the outlet pressure measuring pipe, and then the diffuser pipe, suction pipe, inlet pressure measuring pipe and transition pipe are installed. In the suction channel formed by the pump, it is connected with the transition pipe with a flange. The cable of the speed sensor is connected to the speed measuring instrument through the sealing joint on the large flange of the outlet pressure measuring tube. The sealing joint 2 is led out, the small flange end of the outlet pressure measuring tube is flanged to the drain pipe, the drain pipe is flanged to the upstream straight pipe section of the flowmeter, the upstream straight pipe section of the flowmeter, the flowmeter, the downstream straight pipe section of the flowmeter, and the flow adjustment The valve and the inlet of the cavitation tank are connected by flanges. The top of the cavitation tank is equipped with an exhaust valve and an exhaust valve. The exhaust valve is connected to the vacuum pump through the exhaust pipe. There is a drain valve at the bottom and a water injection valve in the middle. , There is also a liquid level gauge on the outside, the outlet of the cavitation tank is located in the middle, and the inlet is located at the bottom, and the inlet and outlet of the cavitation tank are separated by a partition.

The outer diameters of the suction pipe, inlet pressure measuring pipe and transition pipe of the submersible pump NPSH closed-type test device are the same and not less than 2.5 times the outer diameter of the submersible pump, and the length of the suction pipe is not less than 12 times the pipe diameter. The length of the pressure tube is 4 times its diameter, the diameter of the outlet pressure measuring tube is the same as the outlet diameter of the submersible pump, the length of the outlet pressure measuring tube is 4 times its diameter, the straight pipe section upstream of the flow meter and the flow meter and the downstream of the flow meter The straight pipe section has the same caliber, the length of the straight pipe section upstream of the flowmeter is not less than 20 times the pipe diameter, and the length of the straight pipe section downstream of the flowmeter is not less than 5 times the pipe diameter.

The inlet pressure measuring tube of the submersible pump NPSH closed-type test device is welded with an inlet pressure equalizing chamber on the outer side of the middle section of the inlet pressure measuring tube. There are no less than 4 symmetrical inlet water diversion holes symmetrically opened on the inlet pressure measuring tube. The thermometer and the inlet pressure gauge are installed separately. On both sides of the inlet pressure equalization chamber, the middle section of the outlet pressure measuring tube is also provided with an outlet pressure equalization chamber, and the outlet pressure gauge is installed on one side of the outlet pressure equalization chamber, see Figure 2, Figure 3 and Figure 4.

The thermometer, inlet pressure gauge, outlet pressure gauge, speed sensor, speed measuring instrument and flowmeter of the submersible pump NPSH closed test device are used to measure the key parameters of the submersible pump NPSH.

The beneficial effect of the invention is that the critical NPSH of the submersible pump under different flow rates can be measured through the submersible pump NPSH closed-type test device, and the problem that the cavitation performance test of the submersible pump cannot be carried out can be solved.

Description of drawings

Figure 1 is a schematic diagram of a closed-type test device for cavitation performance of a submersible pump; in the figure, 1. Cavitation tank, 2. Outlet, 3. Inlet valve, 4. Differential diffusion tube, 5. Suction pipe, 6. Submersible pump, 7. Thermometer, 8. Inlet pressure gauge, 9. Transition pipe, 10. Sealing joint 1, 11. Speed measuring instrument, 12. Outlet pressure gauge, 13. Drainage pipe, 14. Outlet pressure measuring tube, 15. Sealing joint 2 , 16 flow meter upstream straight pipe section, 17. inlet pressure measuring pipe, 18. speed sensor, 19. flow meter, 20. flow meter downstream straight pipe section, 21. flow regulating valve, 22. water injection valve, 23. vacuum pump, 24. Drain valve, 25. suction pipe, 26. inlet, 27. clapboard, 28. liquid level gauge, 29. suction valve, 30. exhaust valve.

Fig. 2 is a cross-sectional view of the pressure measuring point of the inlet pressure measuring tube 17; in the figure, 31. the inlet pressure equalizing chamber, and 32. the inlet water diversion hole.

FIG. 3 is an axial sectional view of the inlet pressure measuring tube 17 where the pressure is measured.

Fig. 4 is an axial cross-sectional view of the outlet pressure measuring tube 14; in the figure, 33. the outlet pressure equalizing chamber, and 34. the outlet water diversion hole.

Figure 5 is the NPSH curve of the submersible pump.

Detailed ways

Referring to Figure 1, the submersible pump NPSH closed-type test device consists of a cavitation tank 1, an outlet port 2, an inlet valve 3, a non-centric diffusion pipe 4, a suction pipe 5, a submersible pump 6, a thermometer 7, an inlet pressure gauge 8, Transition pipe 9, sealing joint 10, speed measuring instrument 11, outlet pressure gauge 12, drain pipe 13, outlet pressure measuring pipe 14, sealing joint 2 15, flow meter upstream straight pipe section 16, inlet pressure measuring pipe 17, speed sensor 18 , flow meter 19, flow meter downstream straight pipe section 20, flow regulating valve 21, water injection valve 22, vacuum pump 23, drain valve 24, air extraction pipe 25, partition 27, liquid level gauge 28, air extraction valve 29, exhaust valve 30 composition. One end of the inlet valve 3 is flanged to the outlet 2, and the other end is flanged to the heterocentric diffusion pipe 4. The diffusion end of the heterocentric diffusion pipe 4 is welded to one end of the suction pipe 5, and the other end of the suction pipe 5 is connected to the inlet for pressure measurement. One end of the pipe 17 is connected with a flange, and the other end of the inlet pressure measuring pipe 17 is connected with one end of the transition pipe 9 with a flange. The outlet flange of the pump 6 is connected to the large flange of the outlet pressure measuring tube 14, and then put into the suction channel composed of the diffuser tube 4, the suction tube 5, the inlet pressure measuring tube 17 and the transition tube 9, and connected with the transition tube 9 with a flange , the speed sensor 18 cable is drawn through the sealing joint one 10 on the large flange of the outlet pressure measuring tube 14 and connected with the speed measuring instrument 11, and the power cable of the submersible pump 6 is drawn out through the sealing joint two 15 on the large flange of the outlet pressure measuring tube 14, and the outlet The small flange end of the pressure measuring tube 14 is connected to the drain pipe 13 with a flange, and the drain pipe 13 is welded with an elbow. The drain pipe 13 is connected to the upstream straight pipe section 16 of the flowmeter with a flange. 19. The downstream straight pipe section 20 of the flowmeter, the flow regulating valve 21 and the inlet port 26 are all connected by flanges. The top of the cavitation tank 1 is equipped with an exhaust valve 30 and an air extraction valve 29. The air extraction valve 29 passes through the air extraction pipe 25 and The vacuum pump 23 is connected, the bottom is provided with a drain valve 24, the middle part is provided with a water injection valve 22, and the outer side is also provided with a liquid level gauge 28. 2 are separated by a partition 27, the outer diameters of the suction pipe 5, the inlet pressure measuring pipe 17 and the transition pipe 9 are not less than 2.5 times the outer diameter of the submersible pump 6, the length of the suction pipe 4 is not less than 12 times the pipe diameter, and the inlet The length of the pressure measuring tube 17 is 4 times of its diameter, the diameter of the outlet pressure measuring tube 14 is the same as that of the outlet of the submersible pump 6, and the length of the outlet pressure measuring tube 13 is 4 times of its diameter. The straight pipe section 16 and the straight pipe section 20 downstream of the flowmeter have the same caliber, the length of the straight pipe section 16 upstream of the flowmeter is not less than 20 times the pipe diameter, and the length of the straight pipe section 20 downstream of the flowmeter is not less than 5 times the pipe diameter.

Referring to Fig. 2, Fig. 3 and Fig. 4, an inlet pressure equalizing chamber 31 is welded on the outside of the middle section of the inlet piezometric tube 17, and no less than four symmetrical inlet water diversion holes with a diameter of 3 to 6 mm are symmetrically opened on the inlet piezometric pipe 17. The hole 32, the thermometer 7 and the inlet pressure gauge 8 are respectively installed on both sides of the pressure equalizing chamber. The middle section of the outlet pressure measuring tube 14 is also provided with an outlet pressure equalizing chamber 33, and the outlet pressure measuring tube 14 is symmetrically opened with no less than four symmetrical outlet water diversion holes 34 with a diameter of 3 to 6 mm, and the outlet pressure gauge 12 is installed at the outlet. One side of the equalizing chamber 33.

The test process of submersible pump NPSH: Before the cavitation test, close all valves on the cavitation tank except the exhaust valve 30 and the water injection valve 22, open the inlet valve 3 and the flow regulating valve 21, and pass clean water through the water injection valve 22 Inject the cavitation tank 1, make the water level account for 4/5 of the tank height, close the exhaust valve 30, and open the exhaust valve 29.

The first step of the test is to start the submersible pump 6, adjust the flow regulating valve 21 to make the flow rate reach a predetermined value, adjust the flow regulating valve 21 to make a little negative pressure appear in the inlet pressure of the submersible pump 6, and then adjust the flow regulating valve to maintain the flow rate. Predetermined value, run for a period of time, make submersible pump run stably, read the data on flow meter 19, thermometer 7, inlet pressure gauge 8, outlet pressure gauge 12, speed measuring instrument 11.

In the second step of the test, the vacuum pump 23 is turned on, and the air in the cavitation tank 1 is continuously extracted to reduce the pressure on the liquid surface in the tank, thereby further reducing the inlet pressure of the submersible pump 6, and adjusting the flow regulating valve 21 to keep the flow at a predetermined value. Close the vacuum pump 23, read the data on the flow meter 19, the thermometer 7, the inlet pressure gauge 8, the outlet pressure gauge 12, the speed measuring instrument 11; repeat the second step to obtain the third group of data; When the single-stage head of the submersible pump 6 begins to decline, but it has not dropped to 3% of the single-stage head, special care is required until the single-stage head of the submersible pump 6 drops by more than 3%. The NPSH value is the critical NPSH NPSH3 of the submersible pump 6, and the data points should be denser near the critical NPSH point. The critical NPSH data of submersible pumps at different flow rates can be obtained by adjusting different predetermined flow rates and maintaining them during the test.

Finally, referring to Fig. 5, convert the single-stage lift and NPSH of the submersible pump 6 to the rated speed, and take the NPSH as the abscissa and the single-stage head H of the submersible pump 6 as the ordinate, and draw 6 cavitation performance curves of submersible pumps.

Claims (3)

1. a submersible pump net positive suction head closed test stand, it is characterized in that: described submersible pump net positive suction head closed test stand is by cavitation pot (1), go out head piece (2), inlet valve (3), disloyalty diffusing tube (4), suction pipe (5), submersible pump (6), thermometer (7), inlet pressure table (8), transition tube (9), SEALING FITTING one (10), tachometer of measuring (11), delivery gauge (12), waste pipe (13), outlet pressure-measuring pipe (14), SEALING FITTING two (15), flowmeter upstream straight length (16), entrance pressure-measuring pipe (17), speed probe (18), flowmeter (19), flowmeter downstream straight length (20), flow control valve (21), water injection valve (22), vacuum pump (23), drain valve (24), exhaust tube (25), enter head piece (26), dividing plate (27), level meter (28), extraction valve (29), outlet valve (30) forms, described inlet valve (3) one end with described in go out head piece (2) and be connected by flange, the other end is connected with flange with described disloyalty diffusing tube (4), one end welding of the diffusion end of described disloyalty diffusing tube (4) and described suction pipe (5), the other end of described suction pipe (5) is connected with flange with one end of described entrance pressure-measuring pipe (17), described entrance pressure-measuring pipe (17) the other end is connected with flange with one end of described transition tube (9), described submersible pump (6) outlet(discharge) flange is connected with flange with described transition tube (9) after being connected with the large flange of described outlet pressure-measuring pipe (14) again, the feed cable of described speed probe (18) cable and described submersible pump (6) is drawn by described SEALING FITTING one (10) and described SEALING FITTING two (15) on the large flange of described outlet pressure-measuring pipe (14) respectively, the little flange end of described outlet pressure-measuring pipe (14) is connected with flange with described waste pipe (13), between described waste pipe (13), use elbow welding, described waste pipe (13) is connected with flange with described flowmeter upstream straight length (16), described flowmeter upstream straight length (16), described flowmeter (19), described flowmeter downstream straight length (20), described flow control valve (21) and described in enter between head piece (26) and all with flange, connect, outlet valve (30) and extraction valve (19) are equipped with in cavitation pot (1) top, extraction valve (19) is connected with vacuum pump (23) by exhaust tube (25), bottom is provided with drain valve (24), intermediate portion is provided with water injection valve (22), outside is also provided with level meter (28), the head piece (2) that goes out of cavitation pot (1) is located at middle part, enter head piece (26) and be located at below, in cavitation pot (1), enter head piece (2) and go out between head piece (26) to use dividing plate (27) to separate.

2. submersible pump net positive suction head closed test stand according to claim 1, it is characterized in that: described suction pipe (5), the external diameter of described entrance pressure-measuring pipe (17) and described transition tube (9) is identical and be not less than 2.5 times of described submersible pump (6) external diameter, described suction pipe (5) length is not less than 12 times of its caliber, described entrance pressure-measuring pipe (17) length is its caliber 4 times, the caliber of described outlet pressure-measuring pipe (14) is identical with described submersible pump (6) outlet bore, described outlet pressure-measuring pipe (14) length is its caliber 4 times, described flowmeter (19) and described flowmeter upstream straight length (16) and the same bore of described flowmeter downstream straight length (20), described flowmeter upstream straight length (16) length is not less than 20 times of its caliber, described flowmeter downstream straight length (20) length is not less than 5 times of its caliber.

3. submersible pump net positive suction head closed test stand according to claim 1, is characterized in that: described entrance pressure-measuring pipe (17) and outside, described outlet pressure-measuring pipe (14) stage casing are welded with entrance and all press chamber (31) and outlet pressure measuring cavity (33).