CN108375402B - Online measurement system for overflow of hydropower station water turbine based on shunt sampling method - Google Patents
Online measurement system for overflow of hydropower station water turbine based on shunt sampling method Download PDFInfo
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- CN108375402B CN108375402B CN201810054829.8A CN201810054829A CN108375402B CN 108375402 B CN108375402 B CN 108375402B CN 201810054829 A CN201810054829 A CN 201810054829A CN 108375402 B CN108375402 B CN 108375402B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
Abstract
The invention discloses a hydropower station water turbine overflow online measuring system based on a shunt sampling method, which comprises a pressure main pipeline and a bypass pipeline, wherein a water inlet and a water outlet of the bypass pipeline are respectively communicated with the side wall of the pressure main pipeline, the bypass pipeline is also provided with a first valve, a second valve and a flowmeter, the flowmeter is positioned between the first valve and the second valve, a shunt sampling pipe is arranged in the pressure main pipeline, the side wall of the shunt sampling pipe is provided with a plurality of sampling ports, and the end part of one end of the shunt sampling pipe is connected with the water inlet of the bypass pipeline. The invention greatly reduces the volume of the flowmeter by shunting and sampling, reduces the installation space and further reduces the measurement cost; the diameter of the shunt sampling tube is greatly reduced compared with that of the main pressure steel tube, so that the selection of the flowmeter is more diversified, and the flowmeter with high precision and reliable operation can be preferentially selected; the flowmeter does not need to be calibrated on site, the production is not affected normally, and the calibration is convenient.
Description
Technical Field
The invention belongs to the technical field of hydropower station testing, and particularly relates to a hydropower station water turbine overflow online measuring system based on a split-flow sampling method.
Background
The method has the advantages of improving the operating efficiency of the water turbine, ensuring that the water turbine works in a high-efficiency area, and having very important practical significance for realizing the economic operation of the hydropower station, improving the economic benefit and enhancing the management level. Research shows that even the running efficiency of the water turbine is 0.1 percent, huge economic benefits can be brought; meanwhile, the efficient and accurate measurement of the overflow of the water turbine also provides an important reference basis for formulating a scientific and reasonable control strategy of the generating set and monitoring the running state of the hydroelectric generating set. Therefore, the efficiency test (mainly including flow measurement, power measurement and working head measurement) of the prototype water turbine is very critical, and the flow measurement is the most important link, and meanwhile, the difficulty is the greatest, the workload is the greatest, and the bottleneck and the technical problem which restrict the operation management of the hydropower station are formed.
The main characteristics of the overflow of the hydraulic turbine of the hydropower station are large flow and large diameter of a pressure steel pipe, such as three gorges hydroelectric powerThe station single machine overflow can reach 3.5 multiplied by 106m3The pressure pipe diameter before the inlet section of the volute was 12.4 m. Therefore, most of the existing flow meters and measuring methods have difficulty in meeting the measurement requirement of the overflow of the water turbine. At present, the flow measurement means commonly adopted in the efficiency test of the water turbine at home and abroad comprises a water hammer method (pressure-time method), a current meter method, a volute differential pressure method, an ultrasonic wave method and the like. The water hammer method is internationally applied more, the flow measurement range is wider, but the method is only suitable for high and medium water head power stations, cannot be used for riverbed type hydropower stations, has certain requirements on a measurement pipe section, and cannot be used for long-term continuous online monitoring of unit flow; the current meter method is suitable for various hydropower stations, and is a current measuring method still widely adopted in the efficiency test of water turbines at home and abroad at present. However, the flow velocity meter and the support arrangement thereof have large interference on the flow state, the measurement precision is influenced, and the power generation is influenced because the flow velocity meter needs to be stopped and drained before and after the test; in addition, the current meter method is not suitable for long-term online monitoring of the flow efficiency of hydropower stations; the volute pressure difference method is the simplest method for measuring the flow passing through a water turbine, and can be adopted in a hydropower station with a volute in theory. However, the method can only measure the relative values of the flow and the efficiency, and can be applied only after calibrating the flow coefficient by using other accurate flow measuring methods (such as a speedometer method or a water hammer method), and the measurement error is large when the water turbine has small opening and small flow. Due to the limitation of indoor test conditions, the flow coefficient must be calibrated on site, otherwise the over-flow and the operating efficiency of the water turbine cannot be accurately monitored in real time. The ultrasonic method is the fastest-developing measuring method in recent years, is accurate and reliable, is simple and convenient to install on site, has good real-time performance, does not interfere a flow field, and can be well applied to efficiency tests of water turbines. However, the ultrasonic method is expensive, and due to the limitation of measurement conditions, the unit is required to have a straight pipe section with a sufficient length, but the requirements of the unit on short flow passages and variable cross-section axial flow and cross-flow units are difficult to meet, and how to apply the ultrasonic flow measurement method to the unit needs to be researched.
In summary, at present, although there are numerous methods for measuring the excess flow of the hydraulic turbine in the hydropower station, and new methods and new technologies are continuously developed, how to realize the low-cost and real-time online measurement of the excess flow of the hydraulic turbine is still the key for restricting the efficient and economic operation of the hydropower station.
Disclosure of Invention
The invention aims to provide a hydropower station water turbine overflow online measuring system based on a shunt sampling method, which reduces the volume of a flowmeter through shunt sampling, reduces the installation space and further greatly reduces the measuring cost.
The technical scheme adopted by the invention is as follows: power station hydraulic turbine excess flow on-line measuring system based on reposition of redundant personnel sampling method, including main pressure line and bypass pipeline, the water inlet and the delivery port of bypass pipeline communicate with main pressure line's lateral wall respectively, still be equipped with first valve on the bypass pipeline, second valve and flowmeter, the flowmeter is located between first valve and the second valve, is equipped with the reposition of redundant personnel sampling tube in the main pressure line, the lateral wall of reposition of redundant personnel sampling tube is opened there is a plurality of sample connection, the tip of the one end of reposition of redundant personnel sampling tube is connected with the water inlet of bypass pipeline.
The invention is also characterized in that:
the first valve and the second valve are ball valves.
The flowmeter is a V-cone flowmeter or a turbine flowmeter.
The number of the sampling ports is 3-5.
The pressure main pipeline is an equal-diameter straight pipeline section.
The included angle α between the water inlet of the bypass pipeline and the axis of the pressure main pipeline is 90-120 degrees;
the included angle theta between the pipeline at the water outlet of the bypass pipeline and the axis of the pressure main pipeline is 90-120 degrees.
The invention has the beneficial effects that: the volume of the flowmeter is greatly reduced through shunting and sampling, the installation space is reduced, and the measurement cost is further reduced; the diameter of the shunt sampling tube is greatly reduced compared with that of the main pressure steel tube, so that the selection of the flowmeter is more diversified, and the flowmeter with high precision and reliable operation can be preferentially selected; the flowmeter does not need to be calibrated on site, the production is not affected normally, and the calibration is convenient.
Drawings
Fig. 1 is a schematic structural diagram of an online measurement system for the overflow of a hydraulic turbine of a hydropower station based on a split-flow sampling method.
In the figure, 1 is a main pressure pipeline, 2 is a sampling port, 3 is a shunt sampling pipe, 4 is a bypass pipeline, 5 is a first valve, 6 is a flowmeter, 7 is a second valve, 8 is an included angle α, and 9 is an included angle theta.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The invention provides a hydropower station water turbine overflow online measuring system based on a shunt sampling method, which comprises a main pressure pipeline 1 and a bypass pipeline 4, wherein a water inlet and a water outlet of the bypass pipeline 4 are respectively communicated with the side wall of the main pressure pipeline 1, the bypass pipeline 4 is also provided with a first valve 5, a second valve 7 and a flowmeter 6, the flowmeter 6 is positioned between the first valve 5 and the second valve 7, a shunt sampling pipe 3 is arranged in the main pressure pipeline 1, the side wall of the shunt sampling pipe 3 is provided with a plurality of sampling ports 2, and the end part of one end of the shunt sampling pipe 3 is connected with the water inlet of the bypass pipeline 4.
The first valve 5 and the second valve 7 are ball valves.
The flow meter 6 is a V-cone flow meter or a turbine flow meter.
The number of the sampling ports 2 is 3-5.
The main pressure pipeline 1 is a straight pipeline section with the same diameter.
The included angle α 8 between the pipeline at the water inlet of the bypass pipeline 4 and the axis of the pressure main pipeline 1 is 90-120 degrees;
the included angle theta 9 between the pipeline at the water outlet of the bypass pipeline 4 and the axis of the pressure main pipeline 1 is 90-120 degrees.
When the pressure main pipeline 1 is used, water flow is filled in the pressure main pipeline 1 and is an equal-diameter straight pipeline section, the number of the sampling ports 2 is 3-5 according to the flow condition and the diameter of the pressure main pipeline 1, the sampling ports 2 are located at the positions capable of representing typical flow velocity distribution of the section of the pressure main pipeline 1, if the number of the sampling ports 2 is 4, the sampling ports can be located at the center line of the pressure main pipeline 1, the radius of the 3/4 pressure main pipeline 1, the radius of the 1/2 pressure main pipeline 1 and the radius of the 1/4 pressure main pipeline 1 respectively, the diameter of the shunt sampling pipe 3 is determined by shunt sampling volume flow and a shunt sampling coefficient, the cross section is streamline to reduce flow loss, the included angle α 8 between a water inlet pipeline of the bypass pipeline 4 and the axis of the pressure main pipeline 1 is 90-120 degrees, the included angle theta 9 between a water outlet pipeline of the bypass pipeline 4 and the axis of the pressure main pipeline 1 is 90-120 degrees, and.
The bypass line 4 is provided with a first valve 5, a second valve 7 and a flow meter 6. The first valve 5 and the second valve 7 are respectively positioned at two sides of the flowmeter 6; the selected flowmeter has the advantages of short straight pipe section, wide measurement range, small pressure loss and the like, such as a V-cone flowmeter, a turbine flowmeter and the like.
The implementation method comprises the following steps: 1) selecting and installing auxiliary equipment such as a flowmeter 6, a first valve 5, a second valve 7 and the like; the flowmeter 6 selects a V-cone flowmeter;
2) determining a shunt sampling system K of the measuring system by laboratory tests or field tests, wherein K is the flow Q in the shunt bypass pipeline 4XWith the flow Q in the pressure main conduit 1MRatio of K to QX/QM；
3) Measuring the flow Q through the bypass line 4X；
4) Calculating the flow Q in the pressure main pipe 1MWherein Q isM＝KQX。
The invention has the beneficial effects that: the volume of the flowmeter is reduced through shunting and sampling, the installation space is reduced, and the measurement cost is greatly reduced; the V-cone flowmeter has high precision and reliable operation, so that the flow measurement precision completely meets the field requirement; need not the on-the-spot demarcation, abnormal influence production, and check is convenient.
Claims (5)
1. The online measurement system for the overflow of the hydraulic turbine of the hydropower station based on the shunt sampling method is characterized by comprising a pressure main pipeline (1) and a bypass pipeline (4), wherein a water inlet and a water outlet of the bypass pipeline (4) are respectively communicated with the side wall of the pressure main pipeline (1), the bypass pipeline (4) is further provided with a first valve (5), a second valve (7) and a flowmeter (6), the flowmeter (6) is positioned between the first valve (5) and the second valve (7), a shunt sampling pipe (3) is arranged in the pressure main pipeline (1), the side wall of the shunt sampling pipe (3) is provided with a plurality of sampling ports (2), and the end part of one end of the shunt sampling pipe (3) is connected with the water inlet of the bypass pipeline (4);
the first valve (5) and the second valve (7) are both ball valves;
the flowmeter (6) is a V-cone flowmeter or a turbine flowmeter.
2. The online measurement system for the flow rate of the water turbine of the hydropower station based on the split-flow sampling method as claimed in claim 1, wherein the number of the sampling ports (2) is 3-5.
3. The online measurement system for the flow rate of the water turbine of the hydropower station based on the split-flow sampling method as claimed in claim 1, wherein the main pressure pipeline (1) is a straight pipeline section with a same diameter.
4. The online measurement system for the water turbine overflow of the hydropower station based on the split-flow sampling method as claimed in claim 1, wherein the included angle α (8) between the pipeline at the water inlet of the bypass pipeline (4) and the axis of the main pressure pipeline (1) is 90-120 degrees.
5. The online measurement system for the flow rate of the water turbine of the hydropower station based on the split-flow sampling method as claimed in claim 1, wherein the included angle theta (9) between the pipeline at the water outlet of the bypass pipeline (4) and the axis of the pressure main pipeline (1) is 90-120 degrees.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810054829.8A CN108375402B (en) | 2018-01-19 | 2018-01-19 | Online measurement system for overflow of hydropower station water turbine based on shunt sampling method |
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| CN201810054829.8A CN108375402B (en) | 2018-01-19 | 2018-01-19 | Online measurement system for overflow of hydropower station water turbine based on shunt sampling method |
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| CN108375402B true CN108375402B (en) | 2020-03-31 |
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| CN109029592A (en) * | 2018-09-26 | 2018-12-18 | 张辞源 | A kind of the bypass measuring device and application method of pipeline water flow amount |
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| JP2567097B2 (en) * | 1987-12-11 | 1996-12-25 | 株式会社東芝 | Flow measuring device |
| DE102008023654A1 (en) * | 2008-05-15 | 2009-11-19 | Endress + Hauser Flowtec Ag | Medium i.e. water, flow rate determining and/or controlling method for use in e.g. water flow meter in sewage system, involves writing flag in log book during reversal of sign of measuring signal and displaying sign reversal by flag |
| CN201867209U (en) * | 2010-11-29 | 2011-06-15 | 陕西科技大学 | Flowmeter capable of increasing flowrate of pipeline |
| CN102706397A (en) * | 2012-05-08 | 2012-10-03 | 东北电力科学研究院有限公司 | Water-flow measuring device with large diameter and low pressure head and measuring method |
| CN202734884U (en) * | 2012-08-08 | 2013-02-13 | 辽宁科林环保工程有限责任公司 | Flow measuring unit for steam-condensed water in vacuum pipe of direct air-cooled condenser |
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