CN100480682C - Apparatus for simultaneously monitoring nitrogen monoxide and chlorine hydride gas concentration and measuring method thereof - Google Patents

Abstract

The invention relates to an apparatus and measuring method for monitoring the nitrogen oxide and the hydrochloride at the same time in the field of diode laser spectrum apply technology. The saw-toothed wave from the saw-toothed wave generator 1 is inputted into the current controller 2 which inputs the current signal of the superpose saw-toothed wave into the diode laser 4 which outputs the laser with adjustable light intensity; the laser gets through a first convex lens 5 and becomes to a parallel light and then gets through the mixed gas of the nitrogen oxide and the hydrochloride 9 and a second convex lens 6 into the receiving end of the probe 7 which inputs the laser signal into the computer 8.

Description

Monitor the measuring method of nitrogen monoxide and chlorine hydride gas concentration simultaneously

Technical field

What the present invention relates to is the diode laser spectrum applied technical field, is specifically related to a kind of measuring method that can monitor two kinds of gas concentrations simultaneously.

Background technology

At present, the technology that can realize online gas-monitoring mainly contains difference absorption spectrum (DOAS) technology, laser radar (LIDAR) technology and diode laser spectrum technology.Wherein generally all the applied optics parametric oscillator is as emissive source for the DOAS technology, and the costing an arm and a leg of optical parametric oscillator, and this technology is very high to the requirement of spectroscopic instruments, sensitive detection parts is so cause the cost of equipment set very expensive.The LIDAR technology is subjected to the influence of external environment easily, can descend along with the increase of wind speed as the precision of its measurement, and the maintenance cost of equipment is very high, so it seldom is used for the real-time monitoring to dusty gas, mainly as the generaI investigation of dusty gas.At present, in the world, existing about utilizing the report of diode laser spectrum technology on-line monitoring dusty gas concentration, but mostly be to utilize a diode laser to measure a kind of gas concentration, also have and monitor multiple gases concentration simultaneously, but all will increase the quantity of corresponding diode laser, this will make the cost of gas concentration on-line monitoring equipment increase, and very difficult miniaturization.

Summary of the invention

The objective of the invention is how to utilize a diode laser to measure the problem of nitric oxide gas concentration and chlorine hydride gas concentration simultaneously in order to solve, thereby provide a kind of measuring method of monitoring nitrogen monoxide and chlorine hydride gas concentration simultaneously, it is to utilize a diode laser to reach the purpose of monitoring two kinds of gas concentrations simultaneously, and simple in structure, easy to operate.

Measuring method of the present invention is carried out according to the following steps: one, the sawtooth wave with saw-toothed wave generator output is input in the current controller, current controller is input to the current signal of stack sawtooth wave in the diode laser, the laser that the diode laser output wavelength is adjustable, the centre wavelength of the laser of described wavelength-tunable is 1790nm, is wherein controlled the temperature of diode laser by temperature controller; Two, the laser of described wavelength-tunable obtains directional light at the light output end of first convex lens after through the transmission of first convex lens, described directional light is input to the light input end of second convex lens by the mixed gas of tested nitrogen monoxide and hydrogen chloride, the absorbing phenomenon of gas to light taken place in the process of described directional light by mixed gas, the part light intensity decreasing directional light obtain focused beam through the light output end that is transmitted in second convex lens of second convex lens, described focused beam is detected that device receives and these laser signal data is sent in the computing machine and handles; Three, computing machine is analyzed the concentration that obtains tested nitric oxide gas to the digital signal of sending into and the concentration of hydrogen chloride gas is respectively:

$c_{\left(\mathrm{NO}\right)}=\frac{\ln (I_{0\left(\mathrm{NO}\right)}/I_{\left(\mathrm{NO}\right)})}{{\mathrm{\σ}}_{\left(\mathrm{NO}\right)}L},$ $c_{\left(\mathrm{HCI}\right)}=\frac{\ln (I_{0\left(\mathrm{HCL}\right)}/I_{\left(\mathrm{HCL}\right)})}{{\mathrm{\σ}}_{\left(\mathrm{HCL}\right)}L}$

In the formula, c _(NO)Be the concentration of tested nitric oxide gas, c _(HCL)Be the concentration of tested hydrogen chloride gas, σ _(NO)Be the absorption cross section of nitric oxide gas, σ _(HCL)Be the absorption cross section of hydrogen chloride gas, I _{0 (NO)}For in the laser signal of diode laser 4 output corresponding to the laser energy of nitric oxide gas absorbing wavelength, I _{0 (HCL)}For in the laser signal of diode laser 4 output corresponding to the laser energy of hydrogen chloride gas absorbing wavelength, I _(NO)Be the energy that is absorbed laser afterwards by nitric oxide gas that detector 7 records, I _(HCL)The energy that is chlorinated the laser of hydrogen after absorbing that is that detector 7 records, L are the length of the mixed gas of tested nitrogen monoxide and hydrogen chloride.

Principle of work: as shown in Figure 2, near Wavelength of Laser scalable 1790nm of diode laser 4 outputs; As shown in Figure 3, the light intensity decreasing phenomenon that the light intensity of laser occurs at two wavelength places after the mixed gas by tested nitrogen monoxide and hydrogen chloride, be two dolly dimple a and the b that occurs among Fig. 3, nitric oxide gas produced absorption to laser signal when depression a was illustrated in wavelength and is the 1790.2 nanometer left and right sides, and depression b when being illustrated in wavelength and being the 1791.54 nanometer left and right sides hydrogen chloride laser signal is produced absorption; Comprehensive above-mentioned phenomenon as seen, nitrogen monoxide and the hydrogen chloride gas wavelength when absorbing phenomenon takes place is very approaching, so the present invention can be used for measuring simultaneously this two kinds of gas concentrations.So computing machine uses the software of writing according to Beer-Lambert law (Bill-lambert's law) concentration of nitric oxide production concentration and hydrogen chloride gas is analyzed and to be shown, promptly according to I=I ₀Exp (σ Lc) (L be the length of tested gas, absorption cross section, I that σ is tested gas be record by energy, the I of the laser after the gas absorption ₀Energy for incident laser) calculates the concentration c of tested gas.

The invention effect: the present invention can monitor the concentration of nitric oxide production concentration and hydrogen chloride simultaneously in real time, and monitoring device have simple in structure, volume is little, cost is low, measuring accuracy is high, good stability, the simple advantage of maintenance.

Description of drawings

Fig. 1 is an one-piece construction synoptic diagram of the present invention, and Fig. 2 is the relative intensity of diode laser 4 output wavelength adjustable lasers and the graph of relation of wavelength, and Fig. 3 is the focused beam relative intensity that receives of detector 7 and the graph of relation of wavelength.

Embodiment

In conjunction with Fig. 1 present embodiment is described, the measurement mechanism of this embodiment is by saw-toothed wave generator 1, current controller 2, temperature controller 3, diode laser 4, first convex lens 5, second convex lens 6, detector 7, computing machine 8 is formed, the signal output part of saw-toothed wave generator 1 connects the signal input part of current controller 2, the control output end of current controller 2 connects the current controling end of diode laser 4, the control output end of temperature controller 3 connects the temperature control end of diode laser 4, the laser of diode laser 4 outputs is input to the light input end of first convex lens 5, tested nitrogen monoxide and the mixed gas of hydrogen chloride 9 are between first convex lens 5 and second convex lens 6, be input to the receiving end of detector 7 from the light of the light output end of second convex lens 6 output, the data-signal output terminal of detector 7 connects the data input pin of computing machine 8.

The measuring method of this embodiment is carried out according to the following steps: one, the sawtooth wave with saw-toothed wave generator 1 output is input in the current controller 2, current controller 2 is input to the current signal of stack sawtooth wave in the diode laser 4, the laser that diode laser 4 output wavelengths are adjustable, the centre wavelength of the laser of described wavelength-tunable is 1790nm, is wherein controlled the temperature of diode lasers 4 by temperature controller 3; Two, the laser of described wavelength-tunable obtains directional light at the light output end of first convex lens 5 after through the transmission of first convex lens 5, described directional light is input to the light input end of second convex lens 6 by the mixed gas 9 of tested nitrogen monoxide and hydrogen chloride, the absorbing phenomenon of gas to light taken place in the process of described directional light by mixed gas, the part light intensity decreasing directional light obtain focused beam through the light output end that is transmitted in second convex lens 6 of second convex lens 6, described focused beam is detected that device 7 receives and these laser signal data is sent in the computing machine 8 and handles; Three, 8 pairs of digital signals of sending into of computing machine are analyzed the concentration that obtains tested nitric oxide gas and the concentration of hydrogen chloride gas is respectively:

$c_{\left(\mathrm{NO}\right)}=\frac{\ln (I_{0\left(\mathrm{NO}\right)}/I_{\left(\mathrm{NO}\right)})}{{\mathrm{\σ}}_{\left(\mathrm{NO}\right)}L},$ $c_{\left(\mathrm{HCI}\right)}=\frac{\ln (I_{0\left(\mathrm{HCL}\right)}/I_{\left(\mathrm{HCL}\right)})}{{\mathrm{\σ}}_{\left(\mathrm{HCL}\right)}L}$

In the formula, c _(NO)Be the concentration of tested nitric oxide gas, c _(HCL)Be the concentration of tested hydrogen chloride gas, σ _(NO)Be the absorption cross section of nitric oxide gas, σ _(HCL)Be the absorption cross section of hydrogen chloride gas, I _{0 (NO)}For in the laser signal of diode laser 4 output corresponding to the laser energy of nitric oxide gas absorbing wavelength, I _{0 (HCL)}For in the laser signal of diode laser 4 output corresponding to the laser energy of hydrogen chloride gas absorbing wavelength, I _(NO)Be the energy that is absorbed laser afterwards by nitric oxide gas that detector 7 records, I _(HCL)The energy that is chlorinated the laser of hydrogen after absorbing that is that detector 7 records, L are the length of the mixed gas of tested nitrogen monoxide and hydrogen chloride.

The technical parameter of described saw-toothed wave generator 1 is: the sawtooth wave frequency is that 100mV (millivolt), wavelength tuning range are 1.5nm (nanometer) less than 1kHz (KHz), crest voltage, and it can select model for use is the saw-toothed wave generator of 8210A; The technical parameter of described current controller 2 is: reference current control is that 0～20mA (milliampere), control accuracy are 0.01mA, and it can select model for use is the current controller of LDC200VCSEL; The technical parameter of described temperature controller 3 is: the temperature control scope be 8 ℃～60 ℃ (degree centigrade), temperature-controlled precision is 0.01 ℃, it can select model for use is the temperature controller of TEC2000EC; The technical parameter of described diode laser 4 is: power is 0.7～0.9mW (milliwatt), and it can select model for use is the diode laser of VCL1790; The model that described detector 7 is selected for use is FGA20; Described computing machine 8 contains the software of writing according to the Beer-Lambert law, and it can analyze, calculates and show the concentration of nitric oxide production concentration and hydrogen chloride gas.

Claims (6)

1, monitors the measuring method of nitric oxide concentration and hydrogen cloride concentration simultaneously, it is characterized in that it carries out according to the following steps: one, the sawtooth wave with saw-toothed wave generator (1) output is input in the current controller (2), current controller (2) is input to the current signal of stack sawtooth wave in the diode laser (4), the adjustable laser of diode laser (4) output wavelength, the centre wavelength of the laser of described wavelength-tunable is 1790nm, is wherein controlled the temperature of diode laser (4) by temperature controller (3); Two, the laser of described wavelength-tunable obtains directional light at the light output end of first convex lens (5) after through the transmission of first convex lens (5), described directional light is input to the light input end of second convex lens (6) by tested nitrogen monoxide and the mixed gas of hydrogen chloride (9), the absorbing phenomenon of gas to light taken place in the process of described directional light by mixed gas, the part light intensity decreasing directional light obtain focused beam through the light output end that is transmitted in second convex lens (6) of second convex lens (6), described focused beam is detected that device (7) receives and these laser signal data is sent in the computing machine (8) and handles; Three, computing machine (8) is analyzed the concentration that obtains tested nitric oxide gas to the digital signal of sending into and the concentration of hydrogen chloride gas is respectively:

$c_{\left(\mathrm{NO}\right)}=\frac{\ln (I_{0\left(\mathrm{NO}\right)}/I_{\left(\mathrm{NO}\right)})}{{\mathrm{\σ}}_{\left(\mathrm{NO}\right)}L},c_{\left(\mathrm{HCl}\right)}=\frac{\ln (I_{0\left(\mathrm{HCL}\right)}/I_{\left(\mathrm{HCL}\right)})}{{\mathrm{\σ}}_{\left(\mathrm{HCL}\right)}L}$

In the formula, c _(NO)Be the concentration of tested nitric oxide gas, c _(HCL)Be the concentration of tested hydrogen chloride gas, σ _(NO)Be the absorption cross section of nitric oxide gas, σ _(HCL)Be the absorption cross section of hydrogen chloride gas, I _{0 (NO)}For in the laser signal of diode laser (4) output corresponding to the laser energy of nitric oxide gas absorbing wavelength, I _{0 (HCL)}For in the laser signal of diode laser (4) output corresponding to the laser energy of hydrogen chloride gas absorbing wavelength, I _(NO)Be the energy that is absorbed laser afterwards by nitric oxide gas that detector (7) records, I _(HCL)The energy that is chlorinated the laser of hydrogen after absorbing that is that detector (7) records, L are the length of the mixed gas of tested nitrogen monoxide and hydrogen chloride.

2, measuring method of monitoring nitric oxide concentration and hydrogen cloride concentration simultaneously according to claim 1 is characterized in that the technical parameter of described saw-toothed wave generator (1) is: the sawtooth wave frequency is that 100mV, wavelength tuning range are 1.5nm less than 1kHz, crest voltage.

3, measuring method of monitoring nitric oxide concentration and hydrogen cloride concentration simultaneously according to claim 2 is characterized in that the technical parameter of described current controller (2) is: reference current control is that 0～20mA, control accuracy are 0.01mA.

4, measuring method of monitoring nitric oxide concentration and hydrogen cloride concentration simultaneously according to claim 2 is characterized in that the technical parameter of described temperature controller (3) is: the temperature control scope is that 8～60 ℃, temperature-controlled precision are 0.01 ℃.

5, measuring method of monitoring nitric oxide concentration and hydrogen cloride concentration simultaneously according to claim 2, it is characterized in that the technical parameter of described diode laser (4) is: power is 0.7～0.9mW.

6, measuring method of monitoring nitric oxide concentration and hydrogen cloride concentration simultaneously according to claim 2, it is characterized in that described computing machine (8) contains the software of writing according to the Beer-Lambert law, it can analyze, calculates and show the concentration of nitric oxide production concentration and hydrogen chloride gas.

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