CN113834788A - Laser spectrum multipoint detection system and method for ammonia volatilization flux of farmland - Google Patents
Laser spectrum multipoint detection system and method for ammonia volatilization flux of farmland Download PDFInfo
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 176
- 238000001514 detection method Methods 0.000 title claims abstract description 133
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 82
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
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- 238000012935 Averaging Methods 0.000 description 1
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
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- 239000003337 fertilizer Substances 0.000 description 1
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- 229910000069 nitrogen hydride Inorganic materials 0.000 description 1
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Abstract
The invention discloses a farmland ammonia volatilization flux laser spectrum multipoint detection system, which is characterized in that a detection system is provided with a set of system host machine and a plurality of in-situ detection probes, the in-situ detection probes are grouped, each group of probes synchronously works, and multipoint comparison analysis and detection are realized through multipoint synchronous detection in the same group; different groups of probes are detected in a time-sharing sequence, so that the use efficiency of the detection system is improved; the detection sensitivity is improved by adopting a dual-radio-frequency modulation spectrum technology and combining a long-optical-path absorption cell and a distributed optical fiber network; the method is particularly suitable for detecting the ammonia volatilization flux of the farmland in a small area, does not need gas sampling, and meets the research and application requirements of multipoint comparison detection analysis of the ammonia volatilization flux of the farmland.
Description
Technical Field
The invention relates to a method and a device for detecting gas volatilization flux, in particular to a method and a device for detecting farmland ammonia volatilization flux in situ by laser spectroscopy at multiple points.
Background
Ammonia volatilization after nitrogenous fertilizer is applied to farmlandAn important pathway for nitrogen loss is also one of the major sources of atmospheric ammonia. Relevant researches show that the ammonia volatilization loss of the nitrogen fertilizer applied to the farmland in North China plain in the main food production area of China is about 11.8-18.9%, and the ammonia volatilization loss of the nitrogen fertilizer applied to the paddy field in the Taihu area is as high as 21.8%. Meanwhile, ammonia gas entering atmosphere is easy to react with SO2The fine particles (PM2.5) of aerosol generated by the reaction of NOx and the like are the most main influencing factors for the formation of PM2.5 in China, and the action of the fine particles is obviously higher than that of SO2And NOx. In addition, most of the volatilized ammonia gas may be in the form of NH3、NH4The form of the fertilizer is settled on the surface of the earth, soil acidification and nutrient substance unbalance are caused, the competitive balance among plants is destroyed, water eutrophication is caused, and global climate change is also aggravated. The research on the ammonia volatilization characteristic of the farmland and the development of the low ammonia emission agricultural technology are necessary ways for solving the environmental problem caused by ammonia volatilization, and the key point is to obtain the effective ammonia volatilization flux data of the farmland.
The method for detecting the volatile flux of the farmland gas mainly comprises a box method and a micrometeorology method. In recent years, the microclimate method is well applied to gas flux detection in the field of agricultural ecology under the promotion of rapid development of a spectroscopic gas detection technology with the advantages of high sensitivity and high time resolution, but the method is mainly suitable for gas flux detection in large-scale open areas and cannot be applied to comparison analysis research of small-area farmlands in agricultural science and technology research; the box type method calculates the ammonia volatilization rate by measuring the volatilization amount of the soil ammonia in the area covered by the box type device in a certain time period, and is suitable for a small-block soil gas emission flux analysis test. In the research of the agricultural ammonia emission reduction technology, a plot fertilization comparison experiment method is often adopted, ammonia emission fluxes at different stages are collected through different fertilization modes of a plurality of plots, and the effectiveness of the emission reduction technology is compared. Therefore, the box type method has obvious advantages in the research of agricultural emission reduction technology. However, the traditional box-type analysis method depends on field gas sampling laboratory analysis, has long detection period, poor time correlation and large measurement error, and cannot meet the requirements of related research and application.
Disclosure of Invention
The invention provides a laser spectrum multipoint detection system and method for ammonia volatilization flux of farmland, aiming at avoiding the defects in the prior art and meeting the requirements of relevant research and application.
The invention adopts the following technical scheme for realizing the purpose of the invention:
the invention relates to a laser spectrum multipoint detection system for farmland ammonia volatilization flux, which is used for detecting the farmland ammonia volatilization flux in a small area and is characterized in that: the detection system is characterized in that a set of system host is provided with a plurality of in-situ detection probes, the in-situ detection probes are grouped, each group of probes works synchronously, and multipoint comparison analysis detection is realized through multipoint synchronous detection in the same group; different groups of probes are detected in a time-sharing sequence, so that the use efficiency of the detection system is improved; the sensitivity of the detection system is improved by adopting a dual-radio-frequency modulation spectrum technology and combining a long-optical-path absorption cell and a distributed optical fiber network.
The laser spectrum multipoint detection system for the ammonia volatilization flux of the farmland is also characterized in that: the in-situ detection probes are correspondingly arranged into in-situ point type optical absorption boxes one by one; the in-situ point type optical absorption box is a reverse buckling type square box which is formed by side plates and a top cover and has an open bottom, the top cover can be opened and closed, and the side plates and the top cover are light-transmitting plates; a multi-reflection absorption cell and a near infrared photoelectric detector are arranged in the square box, an incident beam forms first emergent light through multi-reflection of the multi-reflection absorption cell, and the near infrared photoelectric detector is used for detecting the first emergent light and outputting a photoelectric detection signal; each normal position point type optical absorption box is installed at a point position to be detected in a one-to-one correspondence mode, 16 normal position point type optical absorption boxes are set into 4 box groups according to 4 groups, detection time sequences of probes in the same box group are synchronous, the probes in different box groups are detected in a time-sharing sequence mode, and each normal position point type optical absorption box is provided with a photoelectric detection signal output end of an incident light beam lead-in optical fiber and a near infrared photoelectric detector in a one-to-one correspondence mode.
The laser spectrum multipoint detection system for the ammonia volatilization flux of the farmland is also characterized in that: the system host includes: the system comprises a light source module and a system signal processing and control module;
the light source module is used for generating a laser beam for wavelength scanning and dual-radio-frequency modulation detection by a laser, the laser beam is split into a first laser beam and a second laser beam by a 1 × 2 optical fiber beam splitter, the first laser beam is split into 4 detection light beams with the same intensity by a 1 × 4 optical fiber beam splitter and transmitted to a 4 × 16 optical switch, and the 4 × 16 optical switch periodically and sequentially couples the 4 detection light beams to 4 groups of output ends under the control of a signal acquisition and processing circuit; 16 paths of output optical fibers of the 4 x 16 optical switch are connected with the lead-in optical fibers of incident beams of 16 in-situ point type optical absorption boxes in a one-to-one correspondence manner to form a distributed optical fiber multipoint detection module; the second laser beam is collimated by the optical fiber collimator and output to the calibration absorption cell, the output beam of the calibration absorption cell is used as a calibration signal to be connected to the input end of the five-channel phase-locked amplifier through photoelectric conversion of the host near infrared photoelectric detector, and the calibration signal and four-path signals output by the 16 x 4 electronic switch form five-path synchronous input signals of the five-channel phase-locked amplifier;
and the system signal processing and control module is used for leading the five-path synchronous input signals into the signal acquisition and processing circuit through the signal transmission of the five-channel lock-in amplifier and analyzing the signals to obtain a detection result.
The laser spectrum multipoint detection system for the ammonia volatilization flux of the farmland is also characterized in that: in the light source module, a semiconductor laser temperature control circuit controls the working temperature, and a semiconductor laser current control circuit controls the driving current of a laser, so that the output wavelength of the laser is positioned at the center of a preselected isolated absorption line of target gas ammonia molecules; the scanning signal source superposes a 100Hz sawtooth wave scanning signal on the direct current driving current generated by the semiconductor laser current control circuit, so that the output wavelength of the laser periodically and continuously scans in a fixed wavelength range by taking the central wavelength of the absorption line as the center; the first RF modulation signal source outputs RF frequency band signal f1A second RF modulation signal source for outputting RF frequency band signal f2Radio frequency band signal f1And a radio frequency band signal f2The laser driving current is superposed in the radio frequency summation circuit and superposed on the laser driving current output by the semiconductor laser current control circuit through the radio frequency bias circuit, so that the output wavelength of the laser is modulated by radio frequency band dual radio frequency while being periodically scannedForming; the radio frequency band signal f1And a radio frequency band signal f2The frequency interval delta f is selected to be between 5kHz and 50 kHz; the laser is a near-infrared semiconductor laser.
The laser spectrum multipoint detection system for the ammonia volatilization flux of the farmland is also characterized in that: a double-radio frequency modulation reference circuit consisting of a frequency mixer, a low-pass filter and a frequency doubling circuit is arranged in the system signal processing and control module, and the radio frequency signal f1And a radio frequency signal f2Outputting a frequency doubling signal 2 delta f through a dual-radio-frequency modulation reference circuit, accessing the frequency doubling signal 2 delta f into a reference signal input end of a five-channel lock-in amplifier as a phase-sensitive detection reference signal, and simultaneously carrying out phase-sensitive detection on five synchronous input signals input in the five-channel lock-in amplifier to obtain a detection time period T0Continuous dual radio frequency modulation second harmonic spectrum signals of the medium five-path synchronous input signals are used for completing the set continuous time period T0And after detection, continuing the detection of the original point type optical absorption box of the next box group.
The laser spectrum multipoint detection method for the ammonia volatilization flux of farmland is characterized in that the laser spectrum multipoint detection system for the ammonia volatilization flux of farmland is utilized according to the following processes:
before starting detection, the top cover is kept opened, and the ammonia gas in the farmland is in an open natural volatilization state;
when the detection is started, the top cover is controlled to be closed, so that the volatilized farmland ammonia gas is accumulated in the square box; the five-channel phase-locked amplifier simultaneously carries out phase-sensitive detection on the five input signals;
setting the reflection times of the first laser beam in the multi-reflection absorption cell, thereby determining the optical path length L of the first laser beam transmitted in the multi-reflection absorption celliDegree, i represents the ith in-situ point type optical absorption box;
the signal acquisition and processing circuit performs analog-to-digital conversion and acquisition on the output signals of the five-channel lock-in amplifier to obtain 1 calibration signal and 16 in-situ point type optical absorption boxes at ToDetecting the double-radio-frequency modulation second harmonic spectrum signals of the time period, wherein the total number of 17 signals are acquired and combined by the signalsThe processing circuit calculates the collected signals to obtain 16 in-situ point type optical absorption boxes for detecting the farmland ammonia volatilization flux values, and a detection period is completed.
The laser spectrum multipoint detection method for the ammonia volatilization flux of the farmland is also characterized in that:
the signal acquisition and processing circuit calculates and obtains the ammonia volatilization flux value of the farmland at the detection point according to the following mode:
the signal acquisition and processing circuit carries out accumulation average on 17 signals of the dual-radio-frequency modulation second harmonic spectrum signal divided by the scanning period according to the set accumulation times to obtain a time discrete analysis spectrum signal of the 17 signals, wherein the calibration signal analysis spectrum signal uses S0kThe spectral signals of 16 in-situ point type optical absorption boxes are expressed as SikThe ith in-situ spot type optical absorption box is characterized by i, and T is represented by koDetecting time points with discrete time periods;
analysis of spectral signals S with calibration signals0kAnalyzing the spectrum signal S for each in-situ point type optical absorption boxikPerforming on-line calibration to obtain the ammonia concentration C in the ith in-situ point type optical absorption box at the moment kikAccording to ToIn-situ point type optical absorption box ammonia concentration C continuously detected in detection time periodikCalculating the change characteristics to obtain the ammonia volatilization flux of the ith in-situ point type optical absorption box covering the farmland in unit time and unit area;
wherein, the analysis spectral signal S of the ith in-situ point type optical absorption box at the time kikCharacterized in that:
Sik＝AikS0k+B (1)
calculating and obtaining a k time proportionality coefficient A according to the formula (1) by utilizing a linear fitting operation relationikAnd B is a fitting residual error;
the concentration C of ammonia gas in the ith in-situ point type optical absorption box at the moment k is obtained by calculation according to the formula (2)ikComprises the following steps:
wherein:
L0calibrating the optical path length of the absorption cell;
C0the fixed concentration of the ammonia standard gas at one atmospheric pressure in the absorption cell is calibrated;
Lithe optical path length of the ith in-situ point type optical absorption box;
at T0In the detection time period, the top cover of the in-situ point type optical absorption box is closed to form a closed space, and the ammonia volatilization speed of the farmland is uniform, so that the ammonia volatilization speed is uniform at T0The farmland volatile ammonia at the initial stage of the detection time period is accumulated in the in-situ point type optical absorption box, the ammonia concentration is increased linearly and is characterized by the formula (3):
Cik＝Eit+F (3)
the rate E of the increase of the ammonia concentration in the ith in-situ point optical absorption box is obtained by calculation according to the formula (3) by adopting a linear fitting operational relationi(ii) a F is the intercept of the linear fitting;
calculating and obtaining the ammonia volatilization flux H of the detection point of the ith in-situ point type optical absorption box in unit time and unit area of the farmland according to the formula (4)i
Wherein:
Vithe gas volume of the ith in-situ point type optical absorption box;
Mithe coverage farmland area of the ith home point type optical absorption box is shown.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention adopts the dual-radio frequency modulation spectrum technology and combines a long-range optical absorption cell to realize the high-sensitivity detection of the gas concentration, thereby meeting the requirement of in-situ detection of the low-concentration volatile gas in the farmland.
2. According to the invention, the in-situ point type optical absorption box is adopted to realize the in-situ high-sensitivity detection of the ammonia volatilization flux of the farmland, gas sampling and pretreatment are not required, and the accuracy and the real-time performance of the detection of the gas volatilization flux are improved.
3. The invention adopts the distributed optical fiber network technology to realize the multi-point grouping on-line measurement, the multi-point simultaneous measurement in the same group, and the measurement in different groups of measurement points adopts the photoelectric multi-path technology to sequentially measure, thereby not only meeting the application requirements of agricultural emission reduction technology research on the multi-point ammonia volatilization contrast analysis, but also effectively reducing the instrument requirements of the multi-point measurement.
Drawings
FIG. 1 is a schematic diagram of a detection system of the present invention;
FIG. 2 is a schematic structural diagram of an in-situ spot type optical absorption box according to the present invention;
FIG. 3 is a timing diagram of the detection according to the present invention.
Reference numbers in the figures: the laser comprises a laser 1, a semiconductor laser temperature control circuit 2, a semiconductor laser current control circuit 3, a scanning signal source 4, a first radio frequency modulation signal source 5, a second radio frequency modulation signal source 6, a radio frequency summing circuit 7, a radio frequency bias circuit 8, a 1X 2 optical fiber beam splitter 9, a 1X 4 optical fiber beam splitter 10, a 4X 16 optical switch 11, a mixer 12, a 13 low-pass filter 14, a frequency doubling circuit 15, a 16X 4 electronic switch 15, a 16 five-channel phase-locked amplifier 17, a signal acquisition and processing circuit 18, an optical fiber collimator 19, a calibration absorption cell 19, a near infrared photoelectric detector 20, a side plate 37, a top cover 38, an electric push rod 39, a multiple reflection absorption cell 41 and a near infrared photoelectric detector 42.
Detailed Description
The laser spectrum multipoint detection system for the ammonia volatilization flux of farmland is used for detecting the ammonia volatilization flux of farmland in a small area, the detection system is provided with a set of system host machine and a plurality of in-situ detection probes, the in-situ detection probes are grouped, each group of probes synchronously works, and multipoint comparison analysis and detection are realized through multipoint synchronous detection in the same group; different groups of probes are detected in a time-sharing sequence, so that the use efficiency of the detection system is improved; the sensitivity of the detection system is improved by adopting a dual-radio-frequency modulation spectrum technology and combining a long-optical-path absorption cell and a distributed optical fiber network.
Referring to fig. 1 and 2, in the present embodiment, a plurality of in-situ detection probes are correspondingly arranged as in-situ point optical absorption boxes;
the in-situ point optical absorption box shown in fig. 2 is a reverse-buckling type square box with an open bottom, which is composed of a side plate 37 and a top cover 38, the top cover 38 can be opened and closed, the side plate 37 and the top cover 38 are light-transmitting plates and are made of teflon materials, the top cover 38 is supported in a triangular mode by an electric push rod 39, and a control circuit 40 arranged in the square box controls the electric push rod 39 to stretch and retract so as to drive the top cover 38 to be opened and closed; a multi-reflection absorption cell 41 and a near infrared photoelectric detector 42 are arranged in the square box, an incident light beam forms first emergent light through multi-reflection of the multi-reflection absorption cell 41, and the near infrared photoelectric detector 42 is used for detecting the first emergent light and outputting a photoelectric detection signal.
The in-situ point type optical absorption boxes shown in fig. 1 are respectively a 1 st box 21, a 2 nd box 22, a 3 rd box 23, a 4 th box 24, a 5 th box 25, a 6 th box 26, a 7 th box 27, an 8 th box 28, a 9 th box 29, a 10 th box 30, an 11 th box 31, a 12 th box 32, a 13 th box 33, a 14 th box 34, a 15 th box 35 and a 16 th box 36, wherein 16 in total in-situ point type optical absorption boxes are divided into 4 box groups according to 4 components, the 1 st box group is formed by the 1 st box to the 4 th box, the 2 nd box group is formed by the 5 th box to the 8 th box, the 3 rd box group is formed by the 9 th box to the 12 th box, and the 4 th box group is formed by the 13 th box to the 16 th box; each in-situ point type optical absorption box is correspondingly arranged at the point position to be detected one by one, the detection time sequence of each probe in the same box group is synchronous, the probes in different box groups are sequentially detected in a time-sharing mode, and each in-situ point type optical absorption box is correspondingly provided with an incident beam lead-in optical fiber and a photoelectric detection signal output end of the near infrared photoelectric detector 42.
The multiple reflection absorption cell 41 is composed of two spherical mirrors with high reflectivity to near infrared light waves, and the incident light beam is emitted after the incident light beam is repeatedly reflected by the two spherical mirrors by adjusting the angle of the incident light beam.
As shown in fig. 1, the system host in this embodiment includes a light source module and a system signal processing and control module.
The light source module generates a laser beam for wavelength scanning and dual-radio frequency modulation detection by a laser 1, the laser beam is split into a first laser beam and a second laser beam by a 1 × 2 optical fiber beam splitter 9, the first laser beam is split into 4 detection light beams with the same intensity by a 1 × 4 optical fiber beam splitter 10 and transmitted to a 4 × 16 optical switch 11, and the 4 × 16 optical switch 11 periodically and sequentially couples the 4 detection light beams to 4 groups of output ends under the control of a signal acquisition and processing circuit 17; 16 paths of output optical fibers of the 4 x 16 optical switch 11 are connected with the lead-in optical fibers of incident beams of 16 in-situ point type optical absorption boxes in a one-to-one correspondence manner to form a distributed optical fiber multipoint detection module; the second laser beam is collimated by the optical fiber collimator 18 and output to the calibration absorption cell 19, the output beam of the calibration absorption cell 19 is converted by the host near infrared photodetector 20 into a calibration signal, and the calibration signal is connected to the input end of the five-channel lock-in amplifier 16, and forms a five-channel synchronous input signal of the five-channel lock-in amplifier 16 together with the four-channel signal output by the 16 × 4 electronic switch 15.
In the light source module, the semiconductor laser temperature control circuit 2 controls the working temperature, and the semiconductor laser current control circuit 3 controls the laser driving current, so that the output wavelength of the laser 1 is positioned at the center of a preselected isolated absorption line of target gas ammonia molecules; the scanning signal source 4 superposes a 100Hz sawtooth wave scanning signal on the direct current driving current generated by the semiconductor laser current control circuit 3, so that the output wavelength of the laser 1 is periodically and continuously scanned in a fixed wavelength range by taking the central wavelength of an absorption line as a center; the first RF modulation signal source 5 outputs RF frequency band signal f1A second RF modulation signal source 6 outputs a RF frequency band signal f2Radio frequency band signal f1And a radio frequency band signal f2The laser driving current is superposed in a radio frequency summation circuit 7 and superposed on the laser driving current output by the semiconductor laser current control circuit 3 through a radio frequency bias circuit 8, so that the output wavelength of the laser 1 is formed by radio frequency band dual-radio frequency modulation while periodic scanning; radio frequency band signal f1And a radio frequency band signal f2The frequency interval delta f is selected to be between 5kHz and 50 kHz; the laser 1 is a near-infrared semiconductor laser 1.
And the system signal processing and control module is used for leading five paths of synchronous input signals into the signal acquisition and processing circuit 17 through signal transmission of the five-channel lock-in amplifier 16 and analyzing the signals to obtain a detection result.
In-system signal processing and controlThe module is provided with a double-radio frequency modulation reference circuit consisting of a mixer 12, a low-pass filter 13 and a frequency doubling circuit 14, and a radio frequency band signal f1And a radio frequency band signal f2The double-frequency signal 2 delta f is output by the double-radio-frequency modulation reference circuit, the double-frequency signal 2 delta f is connected to the reference signal input end of the five-channel lock-in amplifier 16 to serve as a phase-sensitive detection reference signal, phase-sensitive detection is simultaneously carried out on five synchronous input signals input into the five-channel lock-in amplifier 16 to obtain continuous double-radio-frequency modulation second harmonic spectrum signals of the five synchronous input signals in a detection time period, and after the set continuous time period detection is finished, the detection of the in-situ point type optical absorption box of the next box group is continued.
The dual-radio-frequency modulation spectrum technology adopted by the invention performs dual-radio-frequency high-frequency modulation on the output wavelength of the laser in the radio frequency band, improves the signal spectrum to the radio frequency with higher noise suppression capability, and simultaneously performs detection on the harmonic signal on the low-frequency difference frequency delta f of the two radio frequency signals, thereby reducing the bandwidth requirement of a harmonic signal phase-sensitive detection circuit and realizing the higher signal-to-noise ratio than the traditional low-frequency modulation wavelength modulation spectrum.
The laser spectrum multipoint detection method for the ammonia volatilization flux of the farmland in the embodiment is carried out in the following process:
before the detection is started, the top cover 38 is kept opened, and the ammonia gas in the farmland is in an open natural volatilization state;
when the detection is started, the top cover 38 is controlled to be closed, so that the volatilized farmland ammonia gas is accumulated in the square box; the five-channel phase-locked amplifier 16 simultaneously performs phase-sensitive detection on the five input signals;
the number of reflections of the first laser beam in the multi-reflection absorption cell 41 is set, thereby determining the optical path length L of the first laser beam transmitted in the multi-reflection absorption cell 41iDegree, i represents the ith in-situ point type optical absorption box;
the signal acquisition and processing circuit 17 performs analog-to-digital conversion and acquisition on the output signals of the five-channel lock-in amplifier 16 to obtain 1 calibration signal and 16 in-situ point type optical absorption boxes at ToDetecting 17 secondary harmonic spectrum signals of dual radio frequency modulation in time periodAnd the signal acquisition and processing circuit 17 calculates the acquired signals to obtain ammonia volatilization flux values of farmland at the detection points of the 16 in-situ point type optical absorption boxes, so that detection of 4 groups of 16 in-situ point type optical absorption boxes of the system in one detection period is completed. Fig. 3 shows the sequence of group synchronization detection in one detection cycle, where j is 1, j is 2, j is 3, and j is 4 respectively represent the group numbers of 4 home-point optical absorption boxes.
In specific implementation, the signal acquisition and processing circuit 17 calculates and obtains the ammonia volatilization flux value of the farmland at the detection point according to the following mode:
the signal collecting and processing circuit 17 carries out accumulation averaging on 17 signals of the dual-radio-frequency modulation second harmonic spectrum signal divided by the scanning period according to the set accumulation times to obtain an analysis spectrum signal with time dispersion of the 17 signals, wherein the calibration signal analysis spectrum signal is S0kThe spectral signals of 16 in-situ point type optical absorption boxes are expressed as SikThe ith in-situ spot type optical absorption box is characterized by i, and T is represented by koDetecting time points with discrete time periods;
analysis of spectral signals S with calibration signals0kAnalyzing the spectrum signal S for each in-situ point type optical absorption boxikPerforming on-line calibration to obtain the ammonia concentration C in the ith in-situ point type optical absorption box at the moment kikAccording to ToIn-situ point type optical absorption box ammonia concentration C continuously detected in detection time periodikCalculating the change characteristics to obtain the ammonia volatilization flux of the ith in-situ point type optical absorption box covering the farmland in unit time and unit area;
wherein, the analysis spectral signal S of the ith in-situ point type optical absorption box at the time kikCharacterized in that:
Sik＝AikS0k+B (1)
calculating and obtaining a k time proportionality coefficient A according to the formula (1) by utilizing a linear fitting operation relationikAnd B is a fitting residual error;
the concentration C of ammonia gas in the ith in-situ point type optical absorption box at the moment k is obtained by calculation according to the formula (2)ikComprises the following steps:
wherein:
L0to calibrate the optical path length of the absorption cell (19);
C0for calibrating the fixed concentration of one atmosphere of ammonia standard gas in the absorption cell (19);
Lithe optical path length of the ith in-situ point type optical absorption box;
at T0In the detection time period, the top cover of the in-situ point type optical absorption box is closed to form a closed space, and the ammonia volatilization speed of the farmland is uniform, so that the ammonia volatilization speed is uniform at T0The farmland volatile ammonia at the initial stage of the detection time period is accumulated in the in-situ point type optical absorption box, the ammonia concentration is increased linearly and is characterized by the formula (3):
Cik＝Eit+F (3)
the rate E of the increase of the ammonia concentration in the ith in-situ point optical absorption box is obtained by calculation according to the formula (3) by adopting a linear fitting operational relationi(ii) a F is the intercept of the linear fitting;
calculating and obtaining the ammonia volatilization flux H of the detection point of the ith in-situ point type optical absorption box in unit time and unit area of the farmland according to the formula (4)i
Wherein:
Vithe gas volume of the ith in-situ point type optical absorption box;
Mithe coverage farmland area of the ith home point type optical absorption box is shown.
Aiming at the requirement of the comparative analysis and detection research and application of ammonia volatilization flux of a small-area farmland, the invention adopts a dual-radio-frequency modulation spectrum technology and combines a long-optical-path absorption cell to realize high-sensitivity detection; the number of the detection probes matched with the system host is not limited to 16, and in order to improve the use efficiency of the instrument, the key point is that the requirements of multi-point contrast analysis detection research and application are met aiming at the grouping detection of a plurality of in-situ detection probes.
Claims (7)
1. The utility model provides a farmland ammonia volatilization flux laser spectrum multiple spot detecting system for detect the small region farmland ammonia volatilization flux, characterized by: the detection system is characterized in that a set of system host is provided with a plurality of in-situ detection probes, the in-situ detection probes are grouped, each group of probes works synchronously, and multipoint comparison analysis detection is realized through multipoint synchronous detection in the same group; different groups of probes are detected in a time-sharing sequence, so that the use efficiency of the detection system is improved; the sensitivity of the detection system is improved by adopting a dual-radio-frequency modulation spectrum technology and combining a long-optical-path absorption cell and a distributed optical fiber network.
2. The farmland ammonia volatilization flux laser spectrum multipoint detection system as claimed in claim 1, wherein the plurality of in-situ detection probes are correspondingly arranged into in-situ point type optical absorption boxes one by one; the in-situ point type optical absorption box is a reverse buckling type square box which is formed by a side plate (37) and a top cover (38) and has an open bottom, the top cover (38) can be opened and closed, and the side plate (37) and the top cover (38) are light-transmitting plates; a multi-reflection absorption cell (41) and a near infrared photoelectric detector (42) are arranged in the square box, incident light beams form first emergent light through multi-reflection of the multi-reflection absorption cell (41), and the near infrared photoelectric detector (42) is used for detecting the first emergent light and outputting a photoelectric detection signal; each normal position point type optical absorption box is installed at a point position to be detected in a one-to-one correspondence mode, 16 normal position point type optical absorption boxes are set into 4 box groups according to 4 groups, detection time sequences of probes in the same box group are synchronous, the probes in different box groups are detected in a time-sharing sequence, and each normal position point type optical absorption box is provided with a photoelectric detection signal output end of an incident light beam lead-in optical fiber and a near infrared photoelectric detector (42) in a one-to-one correspondence mode.
3. The farmland ammonia volatilization flux laser spectrum multipoint detection system as claimed in claim 2, which is characterized in that: the system host includes: the system comprises a light source module and a system signal processing and control module;
the light source module is characterized in that a laser (1) generates a laser beam for detection with wavelength scanning and dual-radio frequency modulation, the laser beam is split into a first laser beam and a second laser beam through a 1 x 2 optical fiber beam splitter (9), the first laser beam is split into 4 detection light beams with the same intensity through a 1 x 4 optical fiber beam splitter (10) and transmitted to a 4 x 16 optical switch (11), and the 4 x 16 optical switch (11) periodically and sequentially couples the 4 detection light beams to 4 groups of output ends under the control of a signal acquisition and processing circuit (17); 16 paths of output optical fibers of the 4 x 16 optical switch (11) are connected with the lead-in optical fibers of incident beams of 16 in-situ point type optical absorption boxes in a one-to-one correspondence manner to form a distributed optical fiber multipoint detection module; the second laser beam is collimated by the optical fiber collimator (18) and output to the calibration absorption cell (19), the output beam of the calibration absorption cell (19) is taken as a calibration signal through the photoelectric conversion of the host near infrared photoelectric detector (20) and is connected to the input end of the five-channel phase-locked amplifier (16), and the calibration signal and four signals output by the 16 x 4 electronic switch (15) jointly form five synchronous input signals of the five-channel phase-locked amplifier (16);
and the system signal processing and control module is used for leading the five-path synchronous input signals into a signal acquisition and processing circuit (17) through signal transmission of a five-channel lock-in amplifier (16) and analyzing the signals to obtain a detection result.
4. The farmland ammonia volatilization flux laser spectrum multipoint detection system as claimed in claim 3, which is characterized in that: in the light source module, a semiconductor laser temperature control circuit (2) controls the working temperature, and a semiconductor laser current control circuit (3) controls the driving current of a laser, so that the output wavelength of the laser (1) is positioned at the center of a preselected isolated absorption line of target gas ammonia molecules; a scanning signal source (4) superposes a 100Hz sawtooth wave scanning signal on a direct current driving current generated by a semiconductor laser current control circuit (3), so that the output wavelength of the laser (1) is periodically and continuously scanned in a fixed wavelength range by taking the central wavelength of an absorption line as the center; the first radio frequency modulation signal source (5) outputs a radio frequency band signal f1A second RF modulation signal source (6) outputs a RF band signal f2Radio frequency band signal f1And radio frequencyFrequency band signal f2The laser driving current is superposed in a radio frequency summation circuit (7) and superposed on the laser driving current output by a semiconductor laser current control circuit (3) through a radio frequency bias circuit (8), so that the output wavelength of the laser (1) is formed by radio frequency band dual-radio frequency modulation while periodic scanning; the radio frequency band signal f1And a radio frequency band signal f2The frequency interval delta f is selected to be between 5kHz and 50 kHz; the laser (1) is a near-infrared semiconductor laser (1).
5. The farmland ammonia volatilization flux laser spectrum multipoint detection system as claimed in claim 4, which is characterized in that: a double-radio frequency modulation reference circuit consisting of a mixer (12), a low-pass filter (13) and a frequency doubling circuit (14) is arranged in the system signal processing and control module, and the radio frequency signal f1And a radio frequency signal f2Outputting a frequency doubling signal 2 delta f by a double-radio-frequency modulation reference circuit, accessing the frequency doubling signal 2 delta f into a reference signal input end of a five-channel phase-locked amplifier (16) as a phase-sensitive detection reference signal, and simultaneously carrying out phase-sensitive detection on five synchronous input signals input in the five-channel phase-locked amplifier (16) to obtain a detection time period T0Continuous dual radio frequency modulation second harmonic spectrum signals of the medium five-path synchronous input signals are used for completing the set continuous time period T0And after detection, continuing the detection of the original point type optical absorption box of the next box group.
6. A farmland ammonia volatilization flux laser spectrum multipoint detection method is characterized in that the farmland ammonia volatilization flux laser spectrum multipoint detection system of claim 3 is utilized to carry out the following steps:
before the detection is started, the top cover (38) is kept opened, and the ammonia gas in the farmland is in an open natural volatilization state;
when the detection is started, the top cover (38) is controlled to be closed, so that the volatilized farmland ammonia gas is accumulated in the square box; the five-channel phase-locked amplifier (16) simultaneously carries out phase-sensitive detection on the five input signals;
setting the number of reflections of the first laser beam in a multiple reflection absorption cell (41) to thereby determine the first laser beamThe optical path length L of the light beam transmitted in the multi-reflection absorption cell (41)iDegree, i represents the ith in-situ point type optical absorption box;
the signal acquisition and processing circuit (17) performs analog-to-digital conversion and acquisition on the output signals of the five-channel lock-in amplifier (16) to obtain 1 calibration signal and 16 in-situ point type optical absorption boxes at ToThe dual-radio-frequency modulation second harmonic spectrum signals of the detection time period total 17 signals, and the signal acquisition and processing circuit (17) calculates the acquired signals to obtain 16 in-situ point type optical absorption box detection point farmland ammonia volatilization flux values so as to complete a detection period.
7. The farmland ammonia volatilization flux laser spectrum multipoint detection method as claimed in claim 6, which is characterized in that:
the signal acquisition and processing circuit (17) calculates and obtains the ammonia volatilization flux value of the farmland at the detection point according to the following mode:
the signal acquisition and processing circuit (17) carries out accumulation average on 17 signals of the dual-radio frequency modulation second harmonic wave spectrum signal divided by the scanning period according to the set accumulation times to obtain an analysis spectrum signal with time dispersion of the 17 signals, wherein the calibration signal analysis spectrum signal uses S0kThe spectral signals of 16 in-situ point type optical absorption boxes are expressed as SikThe ith in-situ spot type optical absorption box is characterized by i, and T is represented by koDetecting time points with discrete time periods;
analysis of spectral signals S with calibration signals0kAnalyzing the spectrum signal S for each in-situ point type optical absorption boxikPerforming on-line calibration to obtain the ammonia concentration C in the ith in-situ point type optical absorption box at the moment kikAccording to ToIn-situ point type optical absorption box ammonia concentration C continuously detected in detection time periodikCalculating the change characteristics to obtain the ammonia volatilization flux of the ith in-situ point type optical absorption box covering the farmland in unit time and unit area;
wherein, the analysis spectral signal S of the ith in-situ point type optical absorption box at the time kikCharacterized in that:
Sik＝AikS0k+B (1)
calculating and obtaining a k time proportionality coefficient A according to the formula (1) by utilizing a linear fitting operation relationikAnd B is a fitting residual error;
the concentration C of ammonia gas in the ith in-situ point type optical absorption box at the moment k is obtained by calculation according to the formula (2)ikComprises the following steps:
wherein:
L0to calibrate the optical path length of the absorption cell (19);
C0for calibrating the fixed concentration of one atmosphere of ammonia standard gas in the absorption cell (19);
Lithe optical path length of the ith in-situ point type optical absorption box;
at T0In the detection time period, the top cover of the in-situ point type optical absorption box is closed to form a closed space, and the ammonia volatilization speed of the farmland is uniform, so that the ammonia volatilization speed is uniform at T0The farmland volatile ammonia at the initial stage of the detection time period is accumulated in the in-situ point type optical absorption box, the ammonia concentration is increased linearly and is characterized by the formula (3):
Gik＝Eit+F (3)
the rate E of the increase of the ammonia concentration in the ith in-situ point optical absorption box is obtained by calculation according to the formula (3) by adopting a linear fitting operational relationi(ii) a F is the intercept of the linear fitting;
calculating and obtaining the ammonia volatilization flux H of the detection point of the ith in-situ point type optical absorption box in unit time and unit area of the farmland according to the formula (4)i
Wherein:
Vithe gas volume of the ith in-situ point type optical absorption box;
Miis the ith in-situ spot lightThe area of the chemical absorption box covering the farmland.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115060671A (en) * | 2022-06-09 | 2022-09-16 | 中国科学院南京土壤研究所 | Laser spectrum technology-based farmland ammonia volatilization box type multipoint synchronous in-situ real-time monitoring method |
| CN115615954A (en) * | 2022-12-20 | 2023-01-17 | 合肥金星智控科技股份有限公司 | TDLAS-based ammonia gas online monitoring assembly, monitoring system and monitoring method |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR930010332B1 (en) * | 1990-12-20 | 1993-10-16 | 동양정밀공업 주식회사 | Life information receive terminal for handy |
| US20060215716A1 (en) * | 2005-03-25 | 2006-09-28 | Pavilion Integration Corporation | Radio frequency modulation of variable degree and automatic power control using external photodiode sensor for low-noise lasers of various wavelengths |
| CN1945287A (en) * | 2006-10-17 | 2007-04-11 | 中国科学院安徽光学精密机械研究所 | New nodal real time gas concentration monitoring method and sensor |
| CN101021474A (en) * | 2006-12-05 | 2007-08-22 | 中国科学院安徽光学精密机械研究所 | Opening gas multi-element monitoring instrument and monitoring method |
| US20080171925A1 (en) * | 2007-01-12 | 2008-07-17 | Kexin Xu | Apparatus and method for noninvasive human component measurement with optional optical length |
| CN101806228A (en) * | 2010-02-01 | 2010-08-18 | 南京紫淮矿用电子高科技有限公司 | Coal bed gas radio frequency spectrum direction finding early warning system |
| CN103411919A (en) * | 2013-07-03 | 2013-11-27 | 安徽建筑大学 | System and method for simultaneously monitoring multiple components of building fire early-stage characteristic gases |
| CN104538835A (en) * | 2014-12-09 | 2015-04-22 | 中国科学院上海技术物理研究所 | Linear absorption FM laser frequency stabilizing system and method |
| US20160299065A1 (en) * | 2014-09-29 | 2016-10-13 | Siemens Aktiengesellschaft | Method and Gas Analyzer for Measuring the Concentration of a Gas Component in a Sample Gas |
| CN107093837A (en) * | 2017-06-22 | 2017-08-25 | 北京理工大学 | A kind of radio-frequency modulations pulse laser generation device based on frequency shift feedback loop |
| RU2736178C1 (en) * | 2020-06-09 | 2020-11-12 | федеральное государственное автономное образовательное учреждение высшего образования "Московский физико-технический институт (национальный исследовательский университет)" | Method and device for autonomous remote determination of concentration of atmospheric gas components |
-
2021
- 2021-09-24 CN CN202111123014.9A patent/CN113834788B/en active Active
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR930010332B1 (en) * | 1990-12-20 | 1993-10-16 | 동양정밀공업 주식회사 | Life information receive terminal for handy |
| US20060215716A1 (en) * | 2005-03-25 | 2006-09-28 | Pavilion Integration Corporation | Radio frequency modulation of variable degree and automatic power control using external photodiode sensor for low-noise lasers of various wavelengths |
| CN1945287A (en) * | 2006-10-17 | 2007-04-11 | 中国科学院安徽光学精密机械研究所 | New nodal real time gas concentration monitoring method and sensor |
| CN101021474A (en) * | 2006-12-05 | 2007-08-22 | 中国科学院安徽光学精密机械研究所 | Opening gas multi-element monitoring instrument and monitoring method |
| US20080171925A1 (en) * | 2007-01-12 | 2008-07-17 | Kexin Xu | Apparatus and method for noninvasive human component measurement with optional optical length |
| CN101806228A (en) * | 2010-02-01 | 2010-08-18 | 南京紫淮矿用电子高科技有限公司 | Coal bed gas radio frequency spectrum direction finding early warning system |
| CN103411919A (en) * | 2013-07-03 | 2013-11-27 | 安徽建筑大学 | System and method for simultaneously monitoring multiple components of building fire early-stage characteristic gases |
| US20160299065A1 (en) * | 2014-09-29 | 2016-10-13 | Siemens Aktiengesellschaft | Method and Gas Analyzer for Measuring the Concentration of a Gas Component in a Sample Gas |
| CN104538835A (en) * | 2014-12-09 | 2015-04-22 | 中国科学院上海技术物理研究所 | Linear absorption FM laser frequency stabilizing system and method |
| CN107093837A (en) * | 2017-06-22 | 2017-08-25 | 北京理工大学 | A kind of radio-frequency modulations pulse laser generation device based on frequency shift feedback loop |
| RU2736178C1 (en) * | 2020-06-09 | 2020-11-12 | федеральное государственное автономное образовательное учреждение высшего образования "Московский физико-технический институт (национальный исследовательский университет)" | Method and device for autonomous remote determination of concentration of atmospheric gas components |
Non-Patent Citations (4)
| Title |
|---|
| D. VIVEIROS ET AL.: "Gas sensing using wavelength modulation spectroscopy", PROC. OF SPIE, vol. 9286, 31 December 2014 (2014-12-31) * |
| 伍越 等: "激光稳频控制系统仿真与实验研究", 计算机测量与控制, vol. 26, no. 12, 31 December 2018 (2018-12-31) * |
| 唐七星 等: "调谐激光吸收光谱波长偏移修正算法研究", 光谱学与光谱分析, vol. 38, no. 11, 30 November 2018 (2018-11-30) * |
| 高彦伟 等: "可调谐二极管激光吸收光谱氟化氢检测", 光子学报, vol. 44, no. 6, 30 June 2015 (2015-06-30) * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115060671A (en) * | 2022-06-09 | 2022-09-16 | 中国科学院南京土壤研究所 | Laser spectrum technology-based farmland ammonia volatilization box type multipoint synchronous in-situ real-time monitoring method |
| CN115060671B (en) * | 2022-06-09 | 2024-05-28 | 中国科学院南京土壤研究所 | Farmland ammonia volatilization box type multipoint synchronous in-situ real-time monitoring method based on laser spectrum technology |
| CN115615954A (en) * | 2022-12-20 | 2023-01-17 | 合肥金星智控科技股份有限公司 | TDLAS-based ammonia gas online monitoring assembly, monitoring system and monitoring method |
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