CN103760109B - Optoacoustic measurement method and device of humidity of wet steam - Google Patents
Optoacoustic measurement method and device of humidity of wet steam Download PDFInfo
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Abstract
The invention discloses an optoacoustic measurement device of the humidity of wet steam. The optoacoustic measurement device comprises an optoacoustic cavity, a laser, an electrooptical modulator, sonic transducer arrays, a signal amplifying module and a computer system, wherein the optoacoustic cavity is internally provided with to-be-detected wet steam; the laser acts as an excitation source, is used for emitting lasers to irradiate the wet steam, and exciting the wet steam to generate ultrasonic waves; the electrooptical modulator is positioned on a laser optical path, and is used for modulating the lasers; the sonic transducer arrays are installed on two side walls of the optoacoustic cavity along the optical path, and are used for sensing and detecting ultrasonic wave signals; the signal amplifying module comprises a signal amplifier and a lock phase amplifier which are connected sequentially, and is used for amplifying the ultrasonic wave signals; the computer system is used for analyzing the ultrasonic wave signals so as to obtain the humidity of the wet steam. The invention also discloses an optoacoustic measurement method of the humidity of wet steam. The device and the method can be used for measuring continuously on line under the condition of rapid flowing in a non-contact mode without sampling operation, have tiny interference to a measured wet steam fluid body, and have high measurement flexibility and precision.
Description
Technical field
The present invention relates to measuring wet steam humidity field, the moist steam humidity of more particularly to a kind of use acoustooptics principle is surveyed
Amount device and method.
Background technology
The end of large-scale condensing turbine generally in thermal power plant what, large-size steam turbine, nuclear power in nuclear power station
The work such as warship marine turbing, geothermal power station's steam turbine and middle low-temperature solar generating use or steel, cement, glass, chemical industry
Whole levels of association cogeneration steam turbine or most of level are operated under wet-steam phase in industry flow.In condensing-type vapour
In the power that turbine is sent, the power for having 10%~20% is to change to produce in moist steam region；Nuclear steam turbine is through-flow
In part, the initial steam humidity into high pressure cylinder is usually 0.25%~0.50%, and humidity increases step by step, to high pressure cylinder steam drain
Humidity is up to 12%~15%, and its low pressure (LP) cylinder steam drain humidity is general also up to 12%~14%；And according to Baumann rules, steamer
Occurring 1% medial humidity in machine level can make efficiency reduction about 1%.
The statistics of Britain shows, merely due to the economic loss that the efficiency reduction that humidity causes in steam turbine brings is annual
Up to 50,000,000 pounds.Moreover, the droplets impact blade surface of moist steam high speed flowing causes low pressure grade blade water
Erosion, water erosion will influence the intensity and vibration characteristics of blade, blade is become coarse, pit occurs, is even broken when serious, finally
Lead to a disaster.Meanwhile, water erosion also increases the flow losses of blade flow passage component, cause steam turbine stage efficiency reduction can be up to
0.664%.According to statistics, blade accident ranks first in each part of steam turbine, EPRI-Electric Power Research Institute EPRI (Electric
Power Research Institute) to point out, the 70% of U.S.'s power station steam turbine forced outage rate is relevant with blade damage, and
Various countries' statistics also unanimously shows that the loss that blade accident causes often accounts for half of total loss or so.Used for naval vessel
Steam turbine, in order to improve reliability, increases the service life and reduces maintenance frequency, it is also necessary to take dehumidifying skill in corresponding machine
Art.As can be seen here, the economy and security loss of the steam turbine for being brought by moist steam problem are huge.
In recent years, with the increase of fired power generating unit single-machine capacity, and nuclear power generating sets install proportion increase, due to steam
Humidity problem, the influence to the economy and security of steam turbine operation is more obvious；In addition, the utilization of new energy such as underground heat
During generating, solar energy thermal-power-generating and UTILIZATION OF VESIDUAL HEAT IN generate electricity, also in the urgent need to the humidity of determination moist steam.In wet-steam region, steam
Pressure and temperature be no longer the parameter being each independently of the others as overheated zone, so to determine the state of moist steam, except
Beyond pressure, temperature, it is necessary to find another thermal parameter, determine that the enthalpy of steam, entropy are relatively difficult with the method for measurement,
Therefore, the measurement of humidity just turns into the effective means for determining another state parameter of moist steam.If can accurately be convenient for measuring wet
The humidity of steam, not only helps quickly and accurately to understand and runs in the stage of wet-steam region humidity radially, axially
It is distributed to determine the efficiency of steam turbine, the operation operating personnel to steam turbine provide accurate operating index, but also can be
The optimization design of steam turbine and transformation provide foundation.Also moisture measurement is be unable to do without in research, experiment to steam turbine dehumidifying technology
Technology, the degree of accuracy of its measurement data will directly affect the design quality of dehydrating unit, and only accurate steam wetness measurement is
Accurately judgement can be made to the effect on moisture extraction of newly-designed steam turbine (or stage).Therefore, how to realize that moist steam is wet
Accurate, convenient, the measurement in real time of degree, as one of problem demanding prompt solution, have great significance to fields such as energy source and powers.
The content of the invention
It is an object of the invention to provide a kind of measuring wet steam humidity device and method of use acoustooptics principle, nothing is reached
Disturb, contactless, continuous, online, direct, high sensitivity, high-acruracy survey include diameter from micron（It is even more small）To millimeter
（It is even more big）Saturation water droplet moist steam humidity effect.To achieve the above object, the technical solution adopted by the present invention
For：
A kind of acoustooptics measurement apparatus of moist steam humidity, including：
PA cell, inside is passed through moist steam to be measured；
Laser, is used to send the described moist steam of laser irradiation, and excite moist steam to produce ultrasonic wave as driving source；
Electrooptic modulator, on laser optical path, for being modulated to laser；
Acoustic sensor array, installed in PA cell along light path both sides side wall, for perceiving, detecting ultrasonic signal；
And computer system, for being analyzed treatment to described ultrasonic signal, obtain the humidity of moist steam.
Optical transmission window is provided with the top of the PA cell, laser can pass through described optical transmission window irradiation moist steam.
Described acoustooptics measurement apparatus are additionally provided with the focusing system on the electrooptic modulator emitting light path, are used for
The focus level and degree of collimation of laser are adjusted, control laser irradiates institute with appropriate waist radius, Rayleigh range and the angle of divergence
The moist steam stated.
As improvement, signal amplification module is connected between described acoustic sensor array and computer system；Described
Signal amplification module includes the signal amplifier and lock-in amplifier that are sequentially connected；Described lock-in amplifier also with Electro-optical Modulation
Device is connected, and treatment is amplified to ultrasonic signal according to the modulation system and modulation parameter of the electrooptic modulator.
Signal amplification module is used to be amplified ultrasonic signal treatment, described signal amplifier, by sonic transducer
The small-signal that array detection is obtained is amplified；Tune of electrooptic modulator of the described lock-in amplifier described in laser
Mode processed and control parameter, such as frequency and phase, as reference signal, to tested ultrasonic signal in itself with reference signal with frequency
（Or frequency multiplication）, be amplified with the component of phase, can significantly suppress noise, improve detection signal-to-noise ratio, with detection very high
Sensitivity.
It is present invention also offers a kind of acoustooptics measuring method of moist steam humidity, the laser irradiation after modulation is to be measured
Moist steam simultaneously excites moist steam to produce ultrasonic wave, ultrasonic signal is detected using acoustic sensor array, then to described ultrasound
Ripple signal is analyzed treatment, obtains the humidity of moist steam.
Laser is modulated using electrooptic modulator, according to the modulator approach and control parameter that are pre-designed, control swashs
The rule encouraged the light intensity magnitude of energy-laser and change over time.
Used as improvement, described ultrasonic signal will sequentially pass through signal amplifier and lock-in amplifier treatment, described
Signal amplifier, the small-signal that acoustic sensor array detection is obtained is amplified；Described lock-in amplifier is using described
Electrooptic modulator to the modulation system and control parameter of laser, such as frequency and phase, as reference signal, to being tested ultrasonic wave
Signal is in itself with reference signal with frequency（Or frequency multiplication）, be amplified with the component of phase, can significantly suppress noise, improve detection
Signal to noise ratio, with detection sensitivity very high.
The irradiation of the modulated laser of described moist steam, be excited generation ultrasonic wave, i.e., light is generated in moist steam
Acoustic effect.Because the vehicle repair major of moist steam is in poised state, liquid phase saturation water absorbs heat phase transformation vaporization, and specific volume increases very
It is many characteristics of, stronger than the usual signified optoacoustic effect in single phase gas, liquid or solid.The optoacoustic of moist steam humidity
Measuring method idea is learned to be based on this and produce.Thinking be exactly by study due to phase transformation vaporize enhanced optoacoustic effect come
Reach the purpose of measurement moist steam humidity.Enhancing photoacoustic signal measurement steam is vaporized by the liquid phase in induced with laser moist steam wet
The method of degree is the characteristic parameter according to known PA cell system, control excitation energy input-laser light intensity magnitude and with
Time change, by the phase that is strong and weak, changing over time relation and ultrasonic signal for measuring output energy-ultrasonic signal
With the phase relation of modulation laser, using the calorimetric method of photoacoustic technique, measurement obtains being converted into by laser the heat of heat, so that
Derive because of saturation liquid phase phase transformation vaporization in heated moist steam, become the amount of saturated steam, then by heat transfer, mass transfer and phase
Become vaporescence rule and theoretical model is calculated, finally give the number of saturation water droplet in unknown system variable-moist steam, divide
The important parameters such as cloth, diameter, obtain the humidity of moist steam.
Principle of the invention is as follows：
Liquid phase saturation water droplet in moist steam two-phase, under modulated laser irradiation, absorbs the energy of laser, is changed into
The interior energy of water droplet reclaimed water, because moist steam two-phase is in vehicle repair major poised state, saturation water undergoes phase transition after absorbing heat energy
Vaporization, and be under biphase equilibrium status condition the specific volume of the saturated steam of (saturation pressure or corresponding saturation temperature) than
The specific volume of saturation water is many times greater, thus produces the fluctuation of pressure.The modulation of the energy-laser of excitation causes heating process
It is modulation, i.e., heating process is cycle alternation, thus, the fluctuation of the pressure produced by the heating process of cycle alternation is just produced
Raw ultrasonic wave (if the frequency of modulation is in ultrasonic wave range).
In this series of physical process, there is the transfer process of light-heat-sound multiple kinds of energy form, particularly exist
In thermal process, also there is phase transformation vaporization, it is all linked with one another, intercouple.In conversion process of energy, heat is converted into, is excited and is spoken
Key effect is played, and laser is a kind of highly effective and convenient excitation energy.
The number of liquid phase water droplet, diameter, particle diameter distribution, heat and mass and phase transformation vaporizing property ginseng in moist steam two-phase
Number, the ultrasonic signal parameter, the PA cell that produce（As PA cell or photoacoustic cell, light sound box）Characteristic parameter, noise etc. it is many
Parameter is also intercoupled, and heat-acoustic energy transfer process is played a crucial role.
The photo acoustic method measurement of moist steam humidity is exactly to analyze above-mentioned light-heat-acoustic energy transfer process, multi-parameter coupling
Rule is closed, the characteristic parameter of well-designed PA cell system makes system work in resonant condition, control this complicated energy to change
The change of the excitation energy |input paramete of system（The light intensity magnitude of excitation energy-laser and change over time）, measure final
Energy is exported（The power of ultrasonic signal, the phase and the phase pass for modulating laser that change over time relation and ultrasonic signal
System）, by tool high accuracy calorimetric characteristic photoacoustic technique by measurement obtain heat number, extrapolate because of heated wet steaming
The phase transformation of saturation liquid phase is vaporized into the amount of saturated steam in vapour, then by heat transfer, mass transfer and phase transformation vaporescence rule, extrapolates
Unknown system variable, including the number of saturation water droplet, diameter, particle diameter distribution etc., the i.e. humidity of moist steam in moist steam.
With compared to the prior art, advantages of the present invention is as follows in the past：
1st, can measure comprising diameter from micron（It is even more small）To millimeter（It is even more big）Saturation water droplet moist steam
Humidity, measurement limit is big.
2nd, can continuously, it is online, measure in the case of quick flowing, it is contactless, sampling operation, right need not be carried out
Measured moist steam fluid disturbs few in itself.
3rd, the vaporization phase transition process of saturation water droplet in optoacoustic photothermal technique and moist steam to saturated steam is combined one
Research is played, on the basis of original photo acoustic method has had very high s/n ratio, the specific volume for making full use of phase transformation vaporization zone
The characteristic for greatly increasing, strengthens optoacoustic effect, then increases signal to noise ratio, greatly improves sensitivity and the precision of measurement.
Brief description of the drawings
Fig. 1 is the schematic diagram of the acoustooptics measurement of moist steam humidity of the present invention.
Specific embodiment
As shown in figure 1, the acoustooptics measurement apparatus of moist steam humidity of the invention, including：Laser 1, electrooptic modulator
2nd, focusing system 3, PA cell 4, optical transmission window 5, acoustic sensor array 6, signal amplifier 7, lock-in amplifier 8, the and of computer 9
Speculum 10.
Laser 1 is used to send measurement laser, and is reflected into electrooptic modulator 2 by speculum 10, by Electro-optical Modulation
Device 2 is modulated treatment to laser, and the laser after modulation treatment is focused on by focusing system 3 and irradiates moist steam to be measured.
Moist steam to be measured is passed through in PA cell 4, the top of PA cell 4 is provided with optical transmission window 5, so that laser energy irradiation light
Moist steam in the operatic tunes 4.Acoustic sensor array 6 is also equipped with inside PA cell 4, its sound for including being arranged in the both sides of PA cell 4
Sensor, detects ultrasonic signal, and measure the spatial and temporal distributions of ultrasonic signal.
Signal amplifier 7 is connected with acoustic sensor array 6, the ultrasonic signal obtained to detection（Now ultrasonic signal
Electric signal is converted into via sonic transducer）It is amplified treatment；Lock-in amplifier 8 respectively with signal amplifier 7, Electro-optical Modulation
Device 2 and computer 9 are connected, to through the signal after the enhanced processing of signal amplifier 7, modulation system according to electrooptic modulator 2 and
Modulation parameter is entered horizontal lock enhanced processing and is exported to computer 9, and computer 9 is stored to signal, analyzed and processed, and is calculated
Obtain the humidity of moist steam.
Above-mentioned acoustooptics measurement apparatus, the process for measuring moist steam humidity is as follows：
The laser that laser 1 sends, reflected mirror 10 is modulated into electrooptic modulator 2, and the laser after modulation is through adjusting
Burnt system 3 adjusts the focus level and degree of collimation of laser, and through the optical transmission window 5 on PA cell 4, in irradiation PA cell
Moist steam, inspires ultrasonic wave, by the acoustic sensor array 6 of the both sides of PA cell 4, detects the spatial and temporal distributions of ultrasonic signal, obtains
The ultrasonic signal for arriving（Electric signal）After being amplified by signal amplifier 7, lock-in amplifier 8, stored into computer 9, believed
Number calculate and analyze, finally give the humidity measurements of moist steam.
Claims (3)
1. a kind of acoustooptics measurement apparatus of moist steam humidity, it is characterised in that including：
PA cell, inside is passed through moist steam to be measured；
Laser, is used to send the described moist steam of laser irradiation, and excite moist steam to produce ultrasonic wave as driving source；
Electrooptic modulator, on laser optical path, for being modulated to laser intensity size and the rule for changing over time；
Acoustic sensor array, installed in PA cell along light path both sides side wall, for perceiving, detecting ultrasonic signal；
And computer system, for being analyzed treatment to described ultrasonic signal, obtain the humidity of moist steam；
Described acoustooptics measurement apparatus are additionally provided with the focusing system on the electrooptic modulator emitting light path, for adjusting
The focus level and degree of collimation of laser；
Signal amplification module, described signal amplification module bag are connected between described acoustic sensor array and computer system
Include the signal amplifier and lock-in amplifier being sequentially connected；Described lock-in amplifier is also connected with electrooptic modulator, according to institute
The modulation system for stating electrooptic modulator is amplified treatment to ultrasonic signal；
Optical transmission window is provided with the top of the PA cell, laser irradiates moist steam through described optical transmission window.
2. a kind of acoustooptics measuring method based on acoustooptics measurement apparatus described in claim 1, it is characterised in that after modulation
Laser irradiation PA cell in moist steam to be measured and excite moist steam to produce ultrasonic wave, perceived using acoustic sensor array, inspection
Ultrasonic signal is surveyed, described ultrasonic signal will sequentially pass through signal amplifier and lock-in amplifier treatment, then to described
Ultrasonic signal be analyzed treatment, obtain the humidity of moist steam.
3. the acoustooptics measuring method of moist steam humidity as claimed in claim 2, it is characterised in that utilize electrooptic modulator pair
Laser intensity size and the rule for changing over time are modulated.
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| CN113855535B (en) * | 2021-11-08 | 2022-04-05 | 仪征市人民医院 | Traditional chinese medicine fumigation appearance of portable |
| CN114776390B (en) * | 2022-04-21 | 2023-06-20 | 西安交通大学 | Last-stage stationary blade dehumidification structure based on ultrasonic waves |
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| CN101819146A (en) * | 2010-06-02 | 2010-09-01 | 长沙理工大学 | Method and device for measuring steam humidity and diameter of water droplet of non-contact type turbine |
| CN102680412A (en) * | 2012-05-11 | 2012-09-19 | 江苏舒茨测控设备有限公司 | Method for detecting concentration of trace steam by using photoacoustic spectrometry method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101819146A (en) * | 2010-06-02 | 2010-09-01 | 长沙理工大学 | Method and device for measuring steam humidity and diameter of water droplet of non-contact type turbine |
| CN102680412A (en) * | 2012-05-11 | 2012-09-19 | 江苏舒茨测控设备有限公司 | Method for detecting concentration of trace steam by using photoacoustic spectrometry method |
Non-Patent Citations (1)
| Title |
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| 汽轮机末级湿度测量方法研究现状及其发展;周兰欣等;《华北电力大学学报》;20010630;第28卷(第02期);72-76 * |
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