A device and method for measuring the efficiency of a driving turbine

Abstract

A kind of measuring device and method of driving turbine efficiency, belong to the field of steam turbine, to solve the problem that driving turbine efficiency is not easy to obtain.The present application calibration unit and measuring unit;Calibration unit is used to obtain strain-torque proportionality coefficient k in the offline state of driving turbine;Calibration unit uses horizontal single-end fixed inverted chain to realize the application of static moment, and installs tension sensor before force point;Measuring unit is symmetrically arranged two strain gauges on the middle section of driving turbine output shaft;Two groups of acquisition sub-stations and button cell are symmetrically arranged along shaft shoulder in the middle section of shaft, button cell provides working power for the acquisition sub-station of same group, the strain measured by strain gauge is sent to the acquisition sub-station of same group in wired mode, the strain of two acquisition sub-stations is sent to collector in wireless mode, collector sends two-way strain input signal to PC, obtains torque according to strain and coefficient k, and then obtains driving turbine efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of measuring device and method of driving turbine efficiency, belong to turbine field. BACKGROUND

[0002] Turbine is a kind of using steam or other gas fluid to the acting force of rotor impeller and generates kinetic energy to complete energy conversion device.Turbine efficiency refers to the efficiency of energy conversion in the process of turbine operation, and the efficiency of turbine is an important indicator to measure its performance, and the efficiency measurement or heat consumption measurement of turbine used in power plant is relatively easy, and the output power of turbine connected to generator is relatively easy to obtain.However, compared with driving turbine, as shown in Figure 1 Whether it is condensing or back pressure turbine, it is usually connected to speed reducer and driven equipment, and the output power of driving turbine cannot be directly obtained, and the overall efficiency of system is often obtained, and the efficiency, heat consumption and other indicators of turbine are difficult to accurately obtain, which is not conducive to verifying design and optimizing design. SUMMARY

[0003] In view of the problem that driving turbine efficiency is not easy to obtain, the present application provides a kind of measuring device and method of driving turbine efficiency.

[0004] In one aspect of the present application, a kind of measuring device of driving turbine efficiency is provided, comprising calibration unit and measuring unit;Calibration unit is used to load known static torque on the shaft end of driving turbine output shaft in the off-line state of driving turbine, and the strain is obtained by using measuring unit, and then the strain-torque proportionality coefficient k is obtained;The measuring unit is used to obtain the strain of driving turbine output shaft caused by external force;

[0005] The calibration unit includes tension sensor, chain and row of crane, the shaft end of driving turbine output shaft is fixed by chain, static torque is applied by using horizontally single-end fixed chain, and tension sensor is installed before the force point;

[0006] The measuring unit includes strain gauge, acquisition substation, button cell, collector and PC;Two strain gauges are symmetrically arranged on the middle section of driving turbine output shaft;Two groups of acquisition substation and button cell are symmetrically arranged on the shaft shoulder along the shaft shoulder, and the button cell provides working power for the acquisition substation in the same group, the strain measured by the strain gauge is sent to the acquisition substation in the same group in wired mode, the strain of two acquisition substations is sent to the collector in wireless mode, the collector sends two-way strain input signals to PC, and the torque is obtained according to the strain and strain-torque proportionality coefficient k, and then the driving turbine efficiency is obtained.

[0007] Preferably, the acquisition substation and button cell are equal in weight, and symmetrically distributed on the shaft shoulder.

[0008] Preferably, the strain gauge is model BHF1K.

[0009] Preferably, the Bluetooth transmission is used between the acquisition substation and the collector.

[0010] Preferably, the high-temperature multi-core silver-plated wire with a diameter of 0.15 mm is used to connect the strain gauge and the acquisition substation.

[0011] In another aspect of the present application, a method for measuring the efficiency of a drive turbine is provided, which is realized based on the measuring device for the efficiency of the drive turbine, and comprises the following steps:

[0012] S1, calibration step:

[0013] A known static torque is loaded on the shaft end of the output shaft of the drive turbine, and the strain caused by the deformation of the output shaft is sensed by two strain gauges, and then the strain-torque proportionality coefficient k is obtained.

[0014] where T is the measured torque, and here the known static torque is used as the measured torque, and σ is the strain;

[0015] S2, in the normal operation state of the drive turbine, the strain of the two strain gauges is measured, and the average value is taken as the strain caused by the deformation of the output shaft of the drive turbine;

[0016] S3, the output power P of the drive turbine is obtained:

[0017] P=Tω=kσω, where ω is the angular velocity, and here the torque in the normal operation state of the drive turbine is used as the measured torque T;

[0018] S4, the efficiency η of the drive turbine is obtained:

[0019]

[0020] where h in is the inlet enthalpy, which is obtained by looking up the table according to the inlet pressure and the inlet steam temperature of the drive turbine;

[0021] h s-out is the outlet isentropic enthalpy value, which is obtained by looking up the table according to the outlet pressure and the inlet entropy value of the drive turbine, wherein the inlet entropy value is obtained by looking up the table according to the inlet pressure and the inlet steam temperature of the drive turbine.

[0022] Preferably, the zero point is adjusted before the calibration step, so that the strain is 0 when the zero static torque is input.

[0023] The present application provides a method for measuring the efficiency of a driving turbine, which utilizes the corresponding relationship between strain, torque and shaft power to obtain the output shaft power of the driving turbine and the efficiency of the driving turbine. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a driving turbine operation principle diagram;

[0025] Figure 2 is a principle diagram of the method for measuring the efficiency of a driving turbine according to the present application;

[0026] Figure 3 is a static calibration principle diagram. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0028] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0029] The present application will be further described below with reference to the drawings and specific embodiments, but the present application is not limited by the following description.

[0030] Specific embodiment one: the present embodiment will be described below. Figures 1 to 3 The method for measuring the efficiency of a driving turbine according to the present embodiment includes a calibration unit and a measurement unit. The calibration unit is used to load a known static torque on the shaft end of the output shaft of the driving turbine in the off-line state of the driving turbine, and the measurement unit is used to obtain a strain value and then obtain a strain value-torque proportionality coefficient k. The measurement unit is used to obtain the strain value of the output shaft of the driving turbine caused by external force.

[0031] The calibration unit includes a tension sensor, a chain and a row of cranes. The row of cranes fixes the shaft end of the output shaft of the driving turbine through the chain, realizes the application of the static torque by using the horizontally single-end fixed chain, and installs the tension sensor in front of the force point.

[0032] Referring to Figure 2As shown, the measuring unit includes strain gauges, acquisition sub-stations, button cells, a collector and a PC; two strain gauges are symmetrically arranged on the middle section of the output shaft of the driving turbine; two groups of acquisition sub-stations and button cells are symmetrically arranged on the shaft shoulder along the shaft shoulder; the button cells provide working power for the acquisition sub-stations in the same group; the strain values measured by the strain gauges are transmitted to the acquisition sub-stations in the same group in a wired manner; the strain values of the two acquisition sub-stations are transmitted to the collector in a wireless manner; the collector transmits the two-way strain value input signals to the PC; the torque is obtained according to the strain value and the strain value-torque proportional coefficient k, and then the driving turbine efficiency is obtained. The acquisition sub-stations and button cells are heavy and symmetrically distributed on the shaft shoulder.

[0033] Since the direct stress / strain measurement method is used in the measurement, in order to obtain the measurement data that meets the actual needs to the maximum extent, the HA type semi-bridge with R0=1000Ω, model BHF1K, which has high precision (0.03%) and sensitivity (2.15), is selected as the strain gauge to improve the measurement sensitivity and take into account the measurement range. One strain gauge is arranged on the upper and lower middle sections of the output shaft, and the elements in the same batch are used to further reduce the measurement error caused by environmental temperature and other factors. The temperature range for using the measurement element is -30-80℃.

[0034] In order to reduce the influence of uneven stress at the shaft end, the shaft section is very short. When the elements are arranged on site, they should be arranged at 1 / 2 of the exposed part of the output shaft to obtain higher measurement sensitivity. The temperature of the shaft should not be greater than 45℃ when the strain gauge is installed and the detection assembly is installed, otherwise cooling measures should be taken in advance, which can directly lead to installation failure and the system cannot be used.

[0035] Static calibration is used before measurement. Since the distance between the measurement point and the shaft shoulder is too short, the adaptability to the measurement range is poor, and the calibration is uncertain, so a long calibration time may be required.

[0036] After the above position is selected, the measurement elements will be laid on the selected position according to the process requirements of the "measurement element layout scheme" 24 hours in advance. Since the installation position is not conducive to work, the installation of the elements needs 2 days. About 24 hours after installation, when the protective layer reaches the strength for use, the calibration work can be started.

[0037] Signal acquisition:

[0038] Bluetooth transmission is used between the acquisition sub-station and the collector.

[0039] Bluetooth acquisition sub-station adopts BLE micro-power Bluetooth transmission technology, the core is nRF52xx series MPU, adopts ARM Cortex M4 kernel, supports the latest 5.0 Bluetooth protocol, the theoretical transmission distance is 100 meters, in order to reduce the transmission (amplification, processing, interference, etc.) process error, a high-stability instrument level differential amplifier is added, then a differential ADC acquisition mode is also used, which maximally eliminates the common-mode interference caused by field lead, and improves the system measurement accuracy.

[0040] A disposable battery is used for power supply, in order to maximize the extension of system acquisition and use time, the MPU adopts intermittent wake-up working mode, when receiving the timing wake-up instruction, the sensor is powered and the acquisition is started, then the acquisition result is checked for validity and anti-interference processing, the acquisition sub-station transmits the processing result to the collector through Bluetooth wireless transmission in the form of broadcast.

[0041] In order to prevent accidental signal loss caused by the rotation of the acquisition sub-station with the large shaft, both acquisition and transmission adopt "multiple sampling" processing and redundant transmission backup, which maximally eliminates the influence of "rotation" on the continuity of measurement. Of course, too high speed may always have some signal loss, which can be compensated by data analysis.

[0042] The collector is a BLE master station, when receiving the broadcast result of the acquisition sub-station, after necessary validity judgment, simple post-processing is carried out, and the voltage measurement result is converted, which is directly sent to the USB port of the PC through the high-speed communication port of the MPU, and the acquisition process is completed. In order to maximize "energy saving", the acquisition sub-station and the collector do not process the signal too much, and the communication time is reduced, the data received by the PC needs to be processed in the PC end, such as range and engineering quantity conversion, and necessary data display and recording are completed, so as to realize data analysis and processing in later period.

[0043] Arrangement of each electronic device:

[0044] The strain gauge and the acquisition sub-station are connected by a high-temperature multi-core silver-plated wire with a diameter of Φ0.15 mm. The acquisition sub-station is arranged at the middle segment of the exposed part of the shaft. Since the mass of a single acquisition sub-station is about 8 g, and the total mass of the adhesive is less than 10 g, and the battery and the acquisition sub-station are arranged radially symmetrically along the shaft shoulder, it is expected that the influence on the dynamic balance of the shaft is small. The battery adopts high-capacity disposable lithium battery with a mass of 10 g. Two groups of acquisition sub-stations and batteries are evenly distributed along the circumference, and are symmetrically arranged.

[0045] The collector is not arranged on the output shaft, and is a certain distance away from the output shaft, so it does not affect the dynamic balance of the shaft system. The collector and the PC are connected by a 1.5-meter communication line. The collector itself has a 1.5-meter suction cup antenna.

[0046] Specific implementation method two:Figures 1 to 3 The present application discloses a method for measuring the efficiency of a driving turbine, which is based on a measuring device for the efficiency of the driving turbine. The method comprises the following steps:

[0047] S1, calibration step:

[0048] A known static torque is loaded on the shaft end of the output shaft of the driving turbine. The strain caused by the deformation of the output shaft is sensed by two strain gauges, and then the strain-torque proportional coefficient k is obtained.

[0049] Where T is the measured torque, and the known static torque loaded is used as the measured torque, and σ is the strain.

[0050] S2, in the normal operating state of the driving turbine, the strain of the two strain gauges is measured, and the average value is taken as the strain caused by the deformation of the output shaft of the driving turbine.

[0051] S3, the output power P of the driving turbine is obtained:

[0052] P = Tω = kσω, wherein ω is the angular velocity, and the torque in the normal operating state of the driving turbine is used as the measured torque T.

[0053] S4, the efficiency η of the driving turbine is obtained:

[0054]

[0055] Where h in is the inlet enthalpy, which is obtained by looking up the table according to the inlet pressure and the inlet steam temperature of the driving turbine.

[0056] h s-out is the outlet isentropic enthalpy value, which is obtained by looking up the table according to the outlet pressure and the inlet entropy value of the driving turbine, wherein the inlet entropy value is obtained by looking up the table according to the inlet pressure and the inlet steam temperature of the driving turbine.

[0057] Before the calibration step, the zero point is adjusted so that the strain is 0 when the zero static torque is input.

[0058] The following is a specific embodiment:

[0059] The chain is fixed (locked) at the shaft end, and the force can be applied by using the horizontal single-end fixed "chain", and a tension sensor is installed before the force application point.

[0060] The zero point is adjusted so that the strain measured by the strain gauge is 0 when the zero input is input.

[0061] The force application radius is the output shaft radius, and the force size is obtained by the tension sensor.

[0062] The static torque is loaded by the inverted chain, specifically, the force is measured by the tension sensor F=2000.00kg, and the force radius r=1435 / 2=717.5mm.

[0063] Therefore, the loaded static torque is T=Fr=0.7175×2000×9.8=14063Nm=14.063kNm.

[0064] At this time, the strain value obtained by the strain gauge is 7.29Mv (expressed by the voltmeter).

[0065] Therefore, the strain value-torque proportional coefficient k=14.063kNm / 7.29=1.92908kNm / mv

[0066] Then, the driving turbine is changed into the normal operation state.

[0067] The strain value σ is measured in real time, and the measured torque is T=1.92908σ;

[0068] Therefore, the driving turbine output shaft power is P=1.92908σω;

[0069] Finally, according to

[0070]

[0071] The driving turbine efficiency is obtained.

[0072] Although the present application is described herein with reference to particular embodiments, it is to be understood that these embodiments are merely exemplary of the principles and application of the present application. It is therefore to be understood that numerous modifications can be made to the illustrative embodiments and that other arrangements can be devised without departing from the spirit and scope of the present application as defined by the appended claims. It is to be understood that different dependent claims and features described herein can be combined with each other in ways not explicitly described. It is also to be understood that features described in relation to one embodiment can be used in other embodiments.

Claims

1. A method of measuring the efficiency of a driving turbine, which is realized based on a device for measuring the efficiency of a driving turbine, characterized in that, The measuring device comprises a calibration unit and a measuring unit; the calibration unit is used to load a known static torque on the shaft end of the output shaft of the driving turbine in the off-line state of the driving turbine, and the measuring unit is used to obtain the strain and then obtain the strain-torque proportionality coefficient k; the measuring unit is used to obtain the strain of the output shaft of the driving turbine caused by external force; The calibration unit comprises a tension sensor, an inverted chain and a row of cranes; the row of cranes fixes the shaft end of the output shaft of the driving turbine through the inverted chain, the horizontal single-end fixed inverted chain is used to realize the application of the static torque, and the tension sensor is installed before the force point; The measuring unit comprises strain gauges, acquisition sub-stations, button batteries, a collection device and a PC; two strain gauges are symmetrically arranged on the middle section of the output shaft of the driving turbine; two groups of acquisition sub-stations and button batteries are symmetrically arranged on the shaft shoulder along the shaft shoulder; the button batteries provide working power supply for the acquisition sub-stations in the same group; the strain measured by the strain gauges is transmitted to the acquisition sub-stations in the same group in a wired manner; the strain of the two acquisition sub-stations is transmitted to the collection device in a wireless manner; the collection device transmits the two-way strain input signals to the PC; the torque is obtained according to the strain and the strain-torque proportionality coefficient k, and then the efficiency of the driving turbine is obtained; The measuring method comprises the following steps: S1, calibration step: A known static torque is loaded on the shaft end of the output shaft of the driving turbine; the strain caused by the deformation of the output shaft is sensed by two strain gauges, and then the strain-torque proportionality coefficient k is obtained: where T is the measured torque, here the known static torque of the load, and σ is the strain. S2, in the normal operation state of the driving turbine, the two-way strain is measured by the strain gauges, and the average value is taken as the strain caused by the deformation of the output shaft of the driving turbine; S3, the output power P of the driving turbine is obtained: P = Tω = kσω, wherein ω is the angular velocity, and the torque in the normal operation state of the driving turbine is taken as the measuring torque T; S4, the efficiency η of the driving turbine is obtained: where h in is the inlet enthalpy, obtained from the table according to the inlet pressure and the inlet steam temperature of the driving turbine; h s-out hout is the enthalpy at the turbine inlet, hout is the enthalpy at the turbine outlet, and s is the entropy at the turbine inlet. The enthalpy at the turbine inlet is obtained from a table lookup based on the turbine inlet pressure and the turbine inlet temperature. The enthalpy at the turbine outlet is obtained from a table lookup based on the turbine outlet pressure and the turbine outlet entropy. The turbine outlet entropy is obtained from a table lookup based on the turbine outlet pressure and the turbine outlet temperature.

2. A method of measuring the efficiency of driving a turbine as claimed in claim 1, wherein, The acquisition sub-stations and the button batteries are equal in weight and symmetrically distributed on the shaft shoulder.

3. A method of measuring the efficiency of driving a turbine as claimed in claim 2, wherein, The model of the strain gauge is BHF1K.

4. The method of claim 1, wherein the turbine efficiency is measured by: Bluetooth transmission is adopted between the acquisition sub-stations and the collection device.

5. The method of claim 1, wherein: The high-temperature multi-core silver-plated wire with a diameter of Φ0.15 mm is connected between the strain gauge and the acquisition sub-station.

6. The method of claim 1, wherein: Before the calibration step starts, the zero point is adjusted so that the strain is 0 when the zero static torque is input.

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