CN104280362B - A kind of superheated vapor laser spectrum on-line detecting system - Google Patents

Abstract

The present invention discloses a kind of superheated vapor laser spectrum on-line detecting system, including the near-infrared DFB semiconductor laser of centre wavelength 1397nm, the laser instrument transmitting light beam is divided into reference beam and detection light beam Jing after fiber optic splitter, detection light beam is by detecting while adjacent two characteristic absorpting spectruming lines near near infrared spectrum 1397nm to steam, realize the synchro measure of steam temperature, there is provided the real time temperature parameter needed for water vapor absorption spectroscopic temperature amendment；Using the spectral digital alignment schemes based on double light path, the Accurate align of spectrum cumulative mean process is realized, impact of the drift of output wavelength to detecting in overcoming infrared semiconductor laser continuously to work；Processed using background signal fitting and spectral normalization, eliminate the impact of gas turbulence disturbance and the delustring of environment dust to detecting, and the online accurate measurement of superheated vapor concentration is realized by the strong real time temperature amendment of spectral line.

Description

A kind of superheated vapor laser spectrum on-line detecting system

Technical field

The invention belongs to a kind of laser gas online test method and instrument, specifically a kind of micro- for industrial process high temperature The infrared semiconductor laser spectral measurement method and instrument of amount steam.

Background technology

Steam is a kind of common gas being associated with combustion process of industrial process, and vapour concentration is also that industrial process is excellent Change, process control, and the important parameter of production assurance, for industrial process superheated vapor accurate measurement in work Industry field important in inhibiting and extensive application demand.Traditional water vapor measurement method mainly has electrolysis, capacitance-resistance method, Cold Mirrors method etc. Three types, are applied in conventional environment very well based on the steam measuring instrument of these methods, but industrial process has height The features such as warm, high dust, corrosivity so that traditional steam measuring instrument is in certainty of measurement, service life and environmental suitability side Face is remained in certain gap with practical application in industry demand, it is difficult to meet Trace Water Vapor on-line continuous under industrial process complex environment The requirement of monitoring.In the last few years, with infrared and laser technology fast development, the spectral detection skill based on gas INFRARED ABSORPTION Art has become environment and industrial process trace gas effective detection means, especially with optical communication semiconductor laser conduct The infrared semiconductor laser spectrum detection technique of light source, noncontact which has, highly sensitive, high-resolution feature so as in industry Process gas line detection field has great captivation.As vapour molecule has typical strong suction near infrared spectrum Receive feature, it is possible to achieve highly sensitive, the high-resolution on-line checking of vapour concentration.Therefore, based on infrared semiconductor laser spectrographic method Steam detection method and instrument have notable application prospect in industrial process superheated vapor detection field.

Infrared semiconductor laser spectrum detection technique is the fingerprint absorption characteristic based on gas molecule to infrared spectrum, is utilized The characteristic spectrum of target gas molecules absorbs the qualitative and detection by quantitative realized to gas.It is in Trace gas detection, infrared Semiconductor laser technique can realize the gasmetry sensitivity less than ppm levels.But infrared laser spectroscopy gas detection technology is also Can be affected by various environmental factorss, for the steam infrared semiconductor laser spectral method of detection of industrial process complex environment Need to be further improved in terms of environmental disturbances are eliminated.

The content of the invention

The present invention propose a kind of infrared semiconductor laser spectrum on line detection method for industrial process superheated vapor and System, can realize that the automatic of temperature and concentration of industrial process high temperature steam is measured while monitoring.

The technical solution used in the present invention is as follows：

A kind of superheated vapor laser spectrum on-line detecting system, including the near-infrared dfb semiconductor of centre wavelength 1397nm Laser instrument, laser control module, signal generator, also including 1 × 2 fiber optic splitter, infrared photoelectric detector, low-pass filtering Amplifier, data acquisition and processing (DAP) module, LCDs and refer to absorption cell, transmitting terminal and reflection end, the transmitting terminal It is detection zone and reflection end between, it is characterised in that：Near-infrared dfb semiconductor is controlled by the laser control module to swash Light device output wavelength λ₀Laser, and tuning wavelength λ₀To in two adjacent absorbents line 1397.750nm and 1397.673nm of steam Between near, using 1 × 2 fiber optic splitter by the wavelength X₀Laser be divided into light beam one and light beam two, be respectively acting on reference to inhale Receives pond and detection zone constitute reference path and detection light path, the 100Hz sawtooth signals superposition that the signal generator is produced Wavelength X is made on the sawtooth signal amplitude in the near-infrared DFB semiconductor laser and by adjusting₀Laser in reference light 1397.750nm the and 1397.673nm absorption spectrums of continuous scanning steam on road and detection light path, scanning optical spectrum signal are infrared Photodetector is received and is transmitted to data acquisition and processing (DAP) module, and the data acquisition and processing (DAP) module is using based on double light path Spectral digital alignment schemes, background signal fitting processed with spectral normalization and the strong real time temperature modification method of spectral line Process scanning optical spectrum signal finally realizes the real-time monitoring of the temperature and concentration of steam and in liquid crystal display screen display.

The process of described data acquisition and processing (DAP) module collection and process scanning optical spectrum signal is as follows：

(1), the scanning optical spectrum data of note reference path are with reference to absorption spectrum sequence D_R(n), the scanning of note detection light path Spectroscopic data is detection absorption spectrum sequence D_o(n)；

(2), carry out with reference to absorption spectrum sequence D_R(n) and detection absorption spectrum sequence D_oThe registration process of (n)：Take detection Absorption spectrum sequence D_oN in (), spectral line 1397.750nm centers are used as peak reference position n₀；To with reference to absorption spectrum sequence D_R(n) and detection absorption spectrum sequence D_oN () synchronizes detection, and to reference to absorption spectrum sequence D_RSpectral line in (n) 1397.750nm peak values peak-seeking Correlation Centre position and reference position n₀Skew △ n, obtain detection absorption spectrum sequence in Peak reference position n₀The offset data points △ n of generation, by corresponding detection absorption spectrum sequence D_oN () enters round about Line frequency is moved and eliminates detection absorption spectrum D_oN () is drifted about, then carry out cumulative mean process again；Data handling procedure can be represented For：

(3), registration process is crossed and the detection spectrum D after cumulative mean_oThe intensity normalized of (n)：

Detection spectrum is the absorption signal for being superimposed upon slope background, and absorption intensity is directly proportional to light intensity, is used without absorption Background spectrum area data sequence can be fitted intensity signal, carry out the normalized of spectrum, the light in background spectrum region Fitting function B (n) is by force：

B (n)=b₀+b₁n+b₂n²

The normalization of detection spectrum is by the ratio proccessing realization with background function, the detection spectroscopic data sequence after normalization List is shown as：

For the convenience of detection light Spectrum data processing, the detection spectrum after normalized is converted into into the suction of absorptance Receive spectroscopic data sequence as follows：

Absorptance of the numerical value of each data point of detection spectrum after changing into steam at the corresponding wavelength；

(4) inverting of steam temperature, is carried out using detection spectrum；

A () carries out optic spectrum line linear fitting to detecting spectrum △ D (n), obtain the strong S (T) of absorption line line：

For 1397.750nm the and 1397.673nm absorption lines of steam, selected optical lineshape function carries out two respectively The fitting of the strong S of spectral line line (T), selectes spectrum line style for lorentzian curve, and fitting function relation is as follows：

Wherein, γ_LFor Absorption Line half-breadth, n₀It is the Centre location data point of spectral line；

B () obtains the strong inverting steam temperature of line of steam 1397.750nm and 1397.673nm absorption line using fitting；

Steam spectral line line is by force the function of temperature, the steam 1397.750nm and 1397.673nm obtained using experiment measurement The strong ratio relation of two absorption line lines can with inverting steam temperature, the steam 1397.750nm at arbitrary temperature T and 1397.673nm the intensity of spectral line S of absorption line₁And S (T)₂(T) it is as follows with the inverting relation of the T of steam temperature：

(5), steam detects the temperature adjustmemt of spectrum：

Water vapor absorption spectral line is by force the function of temperature, the strong S (T) of absorption spectrum Absorption Line line and reference under detection temperature T At a temperature of the strong S (T of spectral absorption line line₀) relation is：

Wherein：The total interior partition function that Q (T) is molecule at temperature T, T₀For reference temperature (being taken as 300K), E " to divide Sub- transition low state energy level, ν₀For jump frequency, c₂=hc/k, h are planck constants, and c is the light velocity, and k is Boltzmann constant；Always Interior partition function Q (T) is taken as polynomial form：

Q (T)=a+bT+cT²+dT³

Using vapour molecule spectrum parameter, the steam temperature obtained with reference to front step inverting can be by under detection temperature T Steam spectral line be adapted to by force reference temperature T₀Under carry out vapour concentration inverting, the change for eliminating detection temperature is measured to steam Impact；The present invention enters steam retrieving concentration using stronger 1397.750nm lines in detection spectrum, carries out spectroscopic temperature to which Amendment, to real time inversion vapour concentration；The strong temperature adjustmemt relation of 1397.750nm spectral line lines is：

Wherein：S₁And S (T)₁(T₀) be respectively, E strong with revised spectral line line before 1397.750nm spectral line temperature adjustmemts "₁ And ν₀₁It is the transition low state energy level and mid frequency of 1397.750nm spectral lines respectively；

(6), the strong S of 1397.750nm spectral line crossed using temperature adjustmemt₁(T₀) inverting detect steam concentration C

The calibration of vapour concentration is carried out using the calibration spectrum that instrument prestores, and the acquisition of calibration spectrum is with reference to temperature Degree T₀Under, by the high concentration (C known to insertion in detection light path₀) acquisition of sealing steam standard sample pond, light in standard sample pond Road length is L₀, in calibration spectrum, the line of 1397.750nm lines uses by force S₀₁(T₀) represent, if the 1397.750nm spectrums of detection spectrum Line after the temperature adjustmemt of line uses by force S₁(T₀) represent, detect that the optical path length of light path is L₁, then detect the C of light path vapour concentration Inverting relation is：

The detection light path is made up of transmitting terminal and reflection end, including the transmitting terminal ring flange being oppositely arranged and reflective End flanges disk, is provided with transmitting terminal quartz sealing window, the front end of the transmitting terminal quartz sealing window on the outside of transmitting terminal ring flange It is sequentially provided with 90 ° of off axis paraboloid mirror cylindrical mirrors, fiber collimating lenses and input optical fibre bonder；Outside the reflection end ring flange Side is disposed with reflection end quartz sealing window and corner reflector；In the focus of 90 ° of off axis paraboloid mirror cylindrical mirrors also It is provided with photodetector two；The light beam two is through input optical fibre bonder, fiber collimating lenses, 90 ° of off axis paraboloid mirror cylinders Effect pond is entered from transmitting terminal quartz sealing window after mirror, through quartz sealing two angle of arrival transmitting mirror of window and by corner reflector According to the reversible return of light path, by 90 ° of off axis paraboloid mirror focus of cylindrical mirror to photodetector two, received by photodetector two And signal-transmitting cable exports the low-pass filter amplifier one to mainframe box.

Also include transmitting terminal seal closure, reflection end seal closure, the transmitting terminal seal closure is fixedly connected on transmitting end flanges On disk, 90 ° of off axis paraboloid mirror cylindrical mirrors, fiber collimating lenses and input optical fibre bonder, the quilt of photodetector two It is sealed in transmitting terminal seal closure；The reflection end seal closure is fixedly connected on reflection end ring flange, and the angle transmitting mirror is close It is enclosed in reflection end seal closure.

Further respectively have the fast interface of transmitting terminal outlet, transmitting to bring out on the transmitting terminal seal closure, reflection end seal closure The fast interface of gas and the fast interface of reflection end air inlet, the fast interface of reflection end outlet.

The present invention utilizes newest Near-infrared Tunable semi-conductor laser absorption spectrum method, surveys with reference to infrared laser spectroscopy Temperature technique, based on the spectral digital alignment techniques of double light path, light intensity normalization technology, and infrared spectrum temperature adjustmemt technology reality The online accurate measurement of existing superheated vapor concentration, meets the needs of industrial process superheated vapor on-line checking.

Superheated vapor laser online test method proposed by the present invention is inhaled using infrared-gas molecule " fingerprint " feature Receipts realize that vapour concentration is measured.For the requirement of industrial environment superheated vapor on-line measurement, superheated vapor proposed by the present invention swashs Light online test method is alignd using the spectral digital based on double light path, light intensity signal is fitted and spectral normalization, steam temperature The detection method that combines with spectroscopic temperature amendment of synchro measure, realize superheated vapor high resolution infrared laser spectrum intensity, The self-correction of temperature, meets the highly sensitive on-line measurement requirement of superheated vapor concentration under industrial process complex environment.

Description of the drawings

Fig. 1 show the superheated vapor laser on-line checking instrument structural representation of the present invention；

Fig. 2 show the superheated vapor laser online test method flow chart of data processing figure of the present invention；

Fig. 3 show the background light intensity fitting data choosing principles figure of the present invention；

Fig. 4 show two Absorption Line lines of steam by force and the graph of a relation of ratio and temperature；

Wherein, label in figure：1st, mainframe box, 2,1397nm near-infrared DFB semiconductor lasers, 3,1 × 2 fiber beam splitting Device, 4, optical fiber GRIN Lens, 5, refer to absorption cell, 6, infrared photoelectric detector one, 7, output optical fibre bonder, 8, main frame letter Number cable interface, 9, low-pass filter amplifier one, 10, fan, 11, main power socket, 12, main power switch, 13, DC voltage-stabilizing Power supply, 14, low-pass filter amplifier two, 15, data acquisition and processing (DAP) module, 16, LCDs, 17, signal generator, 18th, semiconductor laser control module, 19, single-mode fiber, 20, signal-transmitting cable, 21, input optical fibre bonder, 22, transmitting End seal closure, 23, the fast interface of transmitting terminal air inlet, 24,90 ° of off axis paraboloid mirror post mirrors, 25, transmitting terminal ring flange, 26, transmitting terminal Quartz sealing window, 27, infrared photoelectric detector two, 28, fiber collimating lenses 2,29, the fast interface of transmitting terminal outlet, 30, send out Penetrate end signal cable interface, 31, the fast interface of reflection end air inlet, 32, corner reflector, 33, reflection end seal closure, 34, reflection end The fast interface of outlet, 35, reflection end quartz sealing window, 36, reflection end ring flange.Above-mentioned part 1-18 constitutes instrument host, Above-mentioned part 21-30 constitutes instrument transmitting terminal, and above-mentioned part 31-36 constitutes instrument reflection end, and main frame passes through single mode with transmitting terminal Optical fiber 19 and signal-transmitting cable 20 connect.

Specific embodiment

As shown in figure 1, a kind of superheated vapor laser spectrum on-line detecting system, including the near-infrared of centre wavelength 1397nm DFB semiconductor laser, laser control module, signal generator, also including 1 × 2 fiber optic splitter, with reference to absorption cell, red Outer photodetector, low-pass filter amplifier, transmitting terminal and reflection end, and data acquisition and processing (DAP) module and liquid crystal display Screen.Transmitting terminal and reflection end are fixed on the corresponding both sides of detection zone by flange respectively and constitute detection light path, using a center Wavelength detects light source, semiconductor laser control module as superheated vapor for the near-infrared DFB semiconductor laser 2 of 1397nm 18 by laser temperature, current control by laser instrument output center wavelength be tuned to two adjacent absorbent line 1397.750nm of steam Near in the middle of 1397.673nm, the 100Hz sawtooth signals that signal generator 17 is produced are superimposed upon semiconductor laser control Its output wavelength continuous rice seedling in a wavelength range is made on electric current, sawtooth signal amplitude is adjusted, is made laser instrument output wave Length continuously scans through above-mentioned two absorption lines.2 Jing fiber couplings of semiconductor laser are exported, by 1 × 2 fiber optic splitter 3 Light beam is pressed into 1:9 are divided into two beams, launch Jing after the collimation of optical fiber collimator 4 compared with low light level beam, and Jing mainframe boxes 1 are built-in to be sealed with high concentration It is irradiated to after the reference absorption cell 5 of steam on 6 photosurface of photodetector, opto-electronic conversion is carried out by photodetector 1, exports Amplification is filtered by low-pass filter amplifier 2 14 with reference to photosignal, and is transferred to data sampling and processing module 15 is carried out Analog digital conversion and digital signal acquiring；1 × 2 fiber optic splitter 3 is exported compared with strong beam by output optical fibre bonder 7 and single-mode optics Fine 19 connect, and the transmitting terminal of beam Propagation to instrument is connected with fiber collimating lenses 28 by input optical fibre bonder 21, light The collimated output of beam, 90 in transmitting terminal ° off axis paraboloid mirrors Zhu Jing, 24 centers are provided with circular light hole, fiber collimating lenses 28 90 ° of 24 central circular light holes of off axis paraboloid mirror post mirror of light beam Jing after collimation, and emitted end quartz sealing window 26 by send out Penetrate to bring out and penetrate, shoot laser beam reaches the reflection end of instrument after detection zone, entered by reflection end quartz sealing window 35 Light beam original optical path is reflected back by reflection end, the corner reflector 32 in reflection end, and the reflected beams are sent out again by detection zone Jing Penetrate end quartz sealing window 26 and return to transmitting terminal, 90 in transmitting terminal ° off axis paraboloid mirror posts mirror 24 will reflect back into the light beam for coming and receive Collect and focus on 27 photosurface of infrared photoelectric detector in transmitting terminal, the light beam of 2 27 pairs of collections of infrared photoelectric detector enters Row opto-electronic conversion, detection photosignal are connected with signal-transmitting cable 20 by transmitting terminal signal cable interface 30, and by master Host signal cable interface 8 on cabinet 1 is transferred to instrument host, into the photosignal after main frame by low-pass filter amplifier One 9 carry out detection signal filtering and amplify, and the detection signal after amplification carries out analog digital conversion by data acquisition and processing (DAP) module 15 And digital signal acquiring, the zigzag scanning synchronization pulse that signal generator 17 is produced is for data sampling and processing module 15 Synchronous triggering to periodic reference photosignal and detection light electric signal data sampling.Data sampling and processing module 15 pairs is adopted The detection signal for collecting carries out the inverting after the cumulative mean in multiple cycles for steam temperature and concentration, the steam that inverting is obtained Temperature and concentration are shown by LCDs 13.The transmitting terminal seal closure 18 and reflection end seal closure 29 of instrument makes transmitting terminal and anti- Penetrate end and be in sealing state, the fast interface 23 of transmitting terminal air inlet and the fast grafting of transmitting terminal outlet are housed on transmitting terminal seal closure 22 Mouth 29, is equipped with the fast interface 31 of reflection end air inlet and the fast interface 34 of reflection end outlet on reflection end seal closure 33, can be respectively High pure nitrogen is continuously passed through or is kept to reflection end and reflection end, prevents from doing detection into steam in transmitting terminal and reflection end Disturb.

Due to being disturbed by environmental factorss during long-term work, its output wavelength has little infrared semiconductor laser Fluctuation, cause the skew of steam spectrum spectrum in each scanning process, directly carry out repeatedly tired average locate to detecting spectrum Comprehend the linear reduction significantly widened, cause accuracy of measurement of derivative spectomstry.Present invention employs a kind of based on double light path Semiconductor laser output beam is divided into two beams by digital spectrum alignment schemes, respectively constitutes reference path and detection light path, weaker It is a branch of built-in by the built-in reference absorption cell arrival mainframe box for being sealed with high concentration steam of mainframe box as reference beam Infrared photoelectric detector, data sampling and processing module carry out data acquisition as reference signal to photosignal, using based on double Spectral digital alignment, light intensity signal fitting and spectral normalization, the synchro measure of steam temperature and the spectroscopic temperature amendment of light path The detection method for combining, realizes superheated vapor high resolution infrared laser spectrum intensity, the self-correction of temperature, meets industrial process The highly sensitive on-line measurement of superheated vapor concentration under complex environment is required.The data processing of superheated vapor laser online test method Flow process is examined signal and detects that the detailed process that spectral signal is processed is as follows as shown in Fig. 2 wherein joining spectrum：

(1) the scanning optical spectrum data of note reference path are with reference to absorption spectrum sequence D_R(n), the scanning light of note detection light path Modal data is detection absorption spectrum sequence D_o(n)；

(2) carry out with reference to absorption spectrum sequence D_R(n) and detection absorption spectrum sequence D_oThe registration process of (n)：Take detection to inhale Receive spectral sequence D_oN in (), spectral line 1397.750nm centers are used as peak reference position n₀；To with reference to absorption spectrum sequence D_R (n) and detection absorption spectrum sequence D_oN () synchronizes detection, and to reference to absorption spectrum sequence D_RSpectral line in (n) 1397.750nm peak values peak-seeking Correlation Centre position and reference position n₀Skew △ n, obtain detection absorption spectrum sequence in Peak reference position n₀The offset data points △ n of generation, by corresponding detection absorption spectrum sequence D_oN () enters round about Line frequency is moved and eliminates detection absorption spectrum D_oN () is drifted about, then carry out cumulative mean process again；Data handling procedure can be represented For：

(3) registration process is crossed and the detection spectrum D after cumulative mean_oThe intensity normalized of (n)；

Detection spectrum is the absorption signal for being superimposed upon slope background, and absorption intensity is directly proportional to light intensity, is used without absorption Background spectrum area data sequence can be fitted intensity signal, carry out the normalized of spectrum, the light in background spectrum region Fitting function B (n) is by force：

B (n)=b₀+b₁n+b₂n²

The normalization of detection spectrum is by the ratio proccessing realization with background function, the detection spectroscopic data sequence after normalization List is shown as：

For the convenience of detection light Spectrum data processing, the detection spectrum after normalized is converted into into the suction of absorptance Receive spectroscopic data sequence as follows：

Absorptance of the numerical value of each data point of detection spectrum after changing into steam at the corresponding wavelength.

(4) inverting of steam temperature is carried out using detection spectrum：

A () carries out optic spectrum line linear fitting to detecting spectrum △ D (n), obtain the strong S (T) of absorption line line：

For 1397.750nm the and 1397.673nm absorption lines of steam, selected optical lineshape function carries out two respectively The fitting of the strong S of spectral line line (T), selectes spectrum line style for lorentzian curve, and fitting function relation is as follows：

Wherein, γ_LFor Absorption Line half-breadth, n₀It is the Centre location data point of spectral line.

B () obtains the strong inverting steam temperature of line of steam 1397.750nm and 1397.673nm absorption line using fitting：

Steam spectral line line is by force the function of temperature, the steam 1397.750nm and 1397.673nm obtained using experiment measurement The strong ratio relation of two absorption line lines can with inverting steam temperature, the steam 1397.750nm at arbitrary temperature T and 1397.673nm the intensity of spectral line S of absorption line₁And S (T)₂(T) it is as follows with the inverting relation of the T of steam temperature：

(5) steam detects the temperature adjustmemt of spectrum：

Water vapor absorption spectral line is by force the function of temperature, under detection temperature T absorbing light spectral line by force with reference temperature under light Strong S (the T of spectrum Absorption Line line₀) relation is：

Wherein：The total interior partition function that Q (T) is molecule at temperature T, T₀For reference temperature (being taken as 300K), E " to divide Sub- transition low state energy level, ν₀For jump frequency, c₂=hc/k, h are planck constants, and c is the light velocity, and k is Boltzmann constant；Always Interior partition function Q (T) is taken as polynomial form：

Q (T)=a+bT+cT²+dT³

Using vapour molecule spectrum parameter, the steam temperature obtained with reference to front step inverting can be by under detection temperature T Steam spectral line be adapted to by force reference temperature T₀Under carry out vapour concentration inverting, the change for eliminating detection temperature is measured to steam Impact.The present invention enters steam retrieving concentration using stronger 1397.750nm lines in detection spectrum, carries out spectroscopic temperature to which Amendment, to real time inversion vapour concentration.The strong temperature adjustmemt relation of 1397.750nm spectral line lines is：

Wherein：S₁And S (T)₁(T₀) be respectively, E strong with revised spectral line line before 1397.750nm spectral line temperature adjustmemts "₁ And ν₀₁It is the transition low state energy level and mid frequency of 1397.750nm spectral lines respectively.

(6) the strong S of spectral line crossed using temperature adjustmemt₁(T₀) inverting detect steam concentration C：

The calibration of vapour concentration is carried out using the calibration spectrum that instrument prestores, and the acquisition of calibration spectrum is with reference to temperature Degree T₀Under, by the high concentration (C known to insertion in detection light path₀) acquisition of sealing steam standard sample pond, light in standard sample pond Road length is L₀, in calibration spectrum, the line of 1397.750nm lines uses by force S₀₁(T₀) represent, if the 1397.750nm lines of detection spectrum Temperature adjustmemt after line use by force S₁(T₀) represent, detect that the optical path length of light path is L₁, then detect that the C of light path vapour concentration is anti- The relation of drilling is：

Claims (4)

1. a kind of near-infrared dfb semiconductor of superheated vapor laser spectrum on-line detecting system, including centre wavelength 1397nm swashs Light device, laser control module, signal generator are also put including 1 × 2 fiber optic splitter, infrared photoelectric detector, low-pass filtering Big device, data acquisition and processing (DAP) module, LCDs and refer to absorption cell, transmitting terminal and reflection end, the transmitting terminal and It is detection zone between reflection end, it is characterised in that：Near-infrared dfb semiconductor laser is controlled by the laser control module Device output wavelength λ₀Laser, and tuning wavelength λ₀To in the middle of two adjacent absorbents line 1397.750nm and 1397.673nm of steam Near, using 1 × 2 fiber optic splitter by the wavelength X₀Laser be divided into light beam one and light beam two, be respectively acting on reference to absorb Pond and detection zone constitute reference path and detection light path, and the 100Hz sawtooth signals that the signal generator is produced are superimposed upon Wavelength X is made on the sawtooth signal amplitude in the near-infrared DFB semiconductor laser and by adjusting₀Laser in reference path With 1397.750nm the and 1397.673nm absorption spectrums of continuous scanning steam in detection light path, scanning optical spectrum signal is by infrared light Electric explorer is received and is transmitted to low-pass filter amplifier and data acquisition and processing (DAP) module, the data acquisition and place successively Reason module is using based on the spectral digital alignment schemes of double light path, background signal fitting and spectral normalization process and spectral line Strong real time temperature modification method process scanning optical spectrum signal finally realizes the real-time monitoring of the temperature and concentration of steam and in liquid Show on crystal display screen；

The process of described data acquisition and processing (DAP) module collection and process scanning optical spectrum signal is as follows：

(1), the scanning optical spectrum data of note reference path are with reference to absorption spectrum sequence D_R(n), the scanning optical spectrum number of note detection light path According to for detect absorption spectrum sequence D_o(n)；

(2), carry out with reference to absorption spectrum sequence D_R(n) and detection absorption spectrum sequence D_oThe registration process of (n)：Take detection to absorb Spectral sequence D_oN in (), spectral line 1397.750nm centers are used as peak reference position n₀；To with reference to absorption spectrum sequence D_R (n) and detection absorption spectrum sequence D_oN () synchronizes detection, and to reference to absorption spectrum sequence D_RSpectral line in (n) 1397.750nm peak values peak-seeking Correlation Centre position and reference position n₀Shifted by delta n, obtain detection absorption spectrum sequence in Peak reference position n₀The offset data points Δ n of generation, by corresponding detection absorption spectrum sequence D_oN () enters round about Line frequency is moved and eliminates detection absorption spectrum D_oN () is drifted about, then carry out cumulative mean process again；Data handling procedure is expressed as：

(3), registration process is crossed and the detection spectrum D after cumulative mean_oN () carries out intensity normalized：

Detection spectrum is the absorption signal for being superimposed upon slope background, and absorption intensity is directly proportional to light intensity, is used without the back of the body of absorption Scape SPECTRAL REGION data sequence is fitted intensity signal, carries out the normalized of spectrum, the light intensity fitting letter in background spectrum region Counting B (n) is：

B (n)=b₀+b₁n+b₂n²

The normalization of detection spectrum is by the ratio proccessing realization with background function, the detection spectroscopic data sequence table after normalization It is shown as：

$D\left(n\right)=\frac{D_0\left(n\right)}{B\left(n\right)}$

For the convenience of detection light Spectrum data processing, the detection spectrum after normalized is converted into into the absorbing light of absorptance Modal data sequence is as follows：

$\mathrm{\Δ}D\left(n\right)=1-\frac{D_0\left(n\right)}{B\left(n\right)}$

Absorptance of the numerical value of each data point of detection spectrum after changing into steam at the corresponding wavelength；

(4) inverting of steam temperature, is carried out using detection spectrum；

A () carries out optic spectrum line linear fitting to detecting spectrum Δ D (n), obtain the strong S (T) of absorption line line：

For 1397.750nm the and 1397.673nm absorption lines of steam, selected optical lineshape function carries out two spectral lines respectively The fitting of the strong S of line (T), selectes spectrum line style for lorentzian curve, and fitting function relation is as follows：

$\mathrm{\Δ}D\left(n\right)=\frac{S\left(T\right)}{\mathrm{\π}}\frac{{\mathrm{\γ}}_L}{\[{(n-n_0)}^2+{{\mathrm{\γ}}_L}^2\]}$

Wherein, γ_LFor Absorption Line half-breadth, n₀It is the Centre location data point of spectral line；

B () obtains the strong inverting steam temperature of line of steam 1397.750nm and 1397.673nm absorption line using fitting；

Steam spectral line line is by force the function of temperature, the steam 1397.750nm and 1397.673nm two obtained using experiment measurement The strong ratio relation inverting steam temperature of absorption line line, the steam 1397.750nm and 1397.673nm at arbitrary temperature T are inhaled Receive the intensity of spectral line S of spectral line₁And S (T)₂(T) it is as follows with the inverting relation of the T of steam temperature：

$R\left(T\right)=\frac{S_1\left(T\right)}{S_2\left(T\right)}=\frac{S_1\left(T_0\right)}{S_2\left(T_0\right)}\exp \[-c_2(E_1^{\′\′}-E_2^{\′\′})(\frac{1}{T}-\frac{1}{T_0})\]$

(5), steam detects the temperature adjustmemt of spectrum：

Water vapor absorption spectral line is by force the function of temperature, the strong S (T) of absorption spectrum Absorption Line line and reference temperature under detection temperature T Under the strong S (T of spectral absorption line line₀) relation is：

$S\left(T\right)=S\left(T_0\right)\frac{Q\left(T_0\right)}{Q\left(T\right)}\frac{\exp (-c_2{E}^{\′\′}/T)}{\exp (-c_2{E}^{\′\′}/T_0)}\frac{\[1-\exp (-c_2{v}_0/T)\]}{\[1-\exp (-c_2{v}_0/T_0)\]}$

Wherein：The total interior partition function that Q (T) is molecule at temperature T, T₀" it is molecular transition for reference temperature (being taken as 300K), E Low state energy level, ν₀For jump frequency, c₂=hc/k, h are planck constants, and c is the light velocity, and k is Boltzmann constant；Partition function Q (T) it is taken as polynomial form：

Q (T)=a+bT+cT²+dT³

Using vapour molecule spectrum parameter, the steam temperature obtained with reference to front step inverting is by the steam light under detection temperature T Spectral line is adapted to by force reference temperature T₀Under carry out vapour concentration inverting, eliminate the impact that the change of detection temperature is measured to steam； The present invention enters steam retrieving concentration using stronger 1397.750nm lines in detection spectrum, spectroscopic temperature amendment is carried out to which, is used With real time inversion vapour concentration；The strong temperature adjustmemt relation of 1397.750nm spectral line lines is：

$S_1\left(T_0\right)=S_1\left(T\right)\frac{Q\left(T\right)}{Q\left(T_0\right)}\frac{\exp (-c_2{E}_1^{\′\′}/T_0)}{\exp (-c_2{E}_1^{\′\′}/T)}\frac{\[1-\exp (-c_2{v}_{01}/T_0)\]}{\[1-\exp (-c_2{v}_{01}/T)\]}$

Wherein：S₁And S (T)₁(T₀) be respectively, E strong with revised spectral line line before 1397.750nm spectral line temperature adjustmemts "₁And ν₀₁ It is the transition low state energy level and mid frequency of 1397.750nm spectral lines respectively；

(6), the strong S of 1397.750nm spectral line crossed using temperature adjustmemt₁(T₀) inverting detect steam concentration C

The calibration of vapour concentration is carried out using the calibration spectrum that instrument prestores, and the acquisition of calibration spectrum is in reference temperature T₀ Under, by the high concentration (C known to insertion in detection light path₀) acquisition of sealing steam standard sample pond, light path in standard sample pond Length is L₀, in calibration spectrum, the line of 1397.750nm lines uses by force S₀₁(T₀) represent, if the 1397.750nm spectral lines of detection spectrum Temperature adjustmemt after line use by force S₁(T₀) represent, detect that the optical path length of light path is L₁, then detect that the C of light path vapour concentration is anti- The relation of drilling is：

$C=\frac{S_1\left(T_0\right)L_1}{S_{01}\left(T_0\right)L_0}{C}_0.$

2. a kind of superheated vapor laser spectrum on-line detecting system according to claim 1, it is characterised in that：The transmitting End and reflection end include the transmitting terminal ring flange being oppositely arranged and reflective end flanges disk, and transmitting is provided with the outside of transmitting terminal ring flange End quartz sealing window, it is accurate that the front end that the transmitting terminal quartz seals window is sequentially provided with 90 ° of off axis paraboloid mirror cylindrical mirrors, optical fiber Straight lens and input optical fibre bonder；The reflection end ring flange be orderly arranged outside each reflection end quartz sealing window and Corner reflector；Photodetector two is additionally provided with the focus of 90 ° of off axis paraboloid mirror cylindrical mirrors；The light beam two is through input Detection zone is entered from transmitting terminal quartz sealing window after fiber coupler, fiber collimating lenses, 90 ° of off axis paraboloid mirror cylindrical mirrors Domain, launches according to the reversible return of light path through reflection end quartz sealing window angle of arrival transmitting mirror and by corner reflector, by 90 ° from Axle parabola focus of cylindrical mirror on photodetector two is received and is exported to master by signal-transmitting cable by photodetector two Low-pass filter amplifier one in cabinet.

3. a kind of superheated vapor laser spectrum on-line detecting system according to claim 2, it is characterised in that：Also include sending out End seal closure, reflection end seal closure are penetrated, the transmitting terminal seal closure is fixedly connected on transmitting terminal ring flange, described 90 ° off-axis Parabola cylindrical mirror, fiber collimating lenses and input optical fibre bonder, photodetector two are sealed in transmitting terminal sealing In cover；The reflection end seal closure is fixedly connected on reflection end ring flange, and described angle transmitting mirror is sealed in reflection end sealing Cover.

4. a kind of superheated vapor laser spectrum on-line detecting system according to claim 3, it is characterised in that：The transmitting The fast interface of transmitting terminal outlet, the fast interface of transmitting terminal outlet and reflection are further respectively had on end seal closure, reflection end seal closure The fast interface of end air inlet, the fast interface of reflection end outlet.