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CN-121994751-A - H (H)2O2Gas TDLAS analyzer

CN121994751ACN 121994751 ACN121994751 ACN 121994751ACN-121994751-A

Abstract

The application discloses an H 2 O 2 gas TDLAS analyzer, and belongs to the technical field of gas concentration detection. In the TDLAS analyzer for the H 2 O 2 gas, the inner surface of a gas path system in contact with the H 2 O 2 gas is subjected to inerting treatment to form a chemical inert layer, so that gas adsorption loss can be effectively restrained, a light path system is arranged in a heat insulation cabinet, a stable physical environment is provided for TDLAS measurement, the instrument is hardly interfered by the field environment and has extremely small long-term drift, a laser driving module adopts a composite current source framework and comprises an operational amplifier serving as an error amplifying stage and a push-pull circuit serving as an output stage, the stability problem under high-current and high-frequency modulation is fundamentally solved, an almost ideal light source modulation signal is provided for TDLAS detection, and a foundation is provided for realizing high-precision harmonic detection. The application deeply couples high-performance driving, reinforced protection and precise environmental control, and effectively improves the precision, stability and reliability of H 2 O 2 gas detection.

Inventors

  • LIU YILING

Assignees

  • 中国计量科学研究院

Dates

Publication Date
20260508
Application Date
20260407

Claims (10)

  1. 1. The H 2 O 2 gas TDLAS analyzer is characterized by comprising a gas path system, a light path system and a driving control system; The gas path system comprises a sample inlet, a mass flow controller, a measuring air chamber, an electronic pressure controller and an air pump which are sequentially connected through a pipeline, wherein the inner surface of the gas path system contacted with the H 2 O 2 gas is subjected to inerting treatment to form a chemical inert layer; the optical path system comprises a laser, an optical path comprising the measuring air chamber and a photoelectric detector which are sequentially connected, wherein the optical path system is arranged in the heat preservation cabinet; The driving control system comprises a main control unit and a laser driving module electrically connected with the main control unit, wherein the laser driving module adopts a composite current source architecture and comprises an operational amplifier serving as an error amplifying stage and a push-pull circuit serving as an output stage.
  2. 2. The H 2 O 2 gas TDLAS analyzer as defined in claim 1, wherein the inert treatment is electropolishing and super-passivating treatment, the chemically inert layer is Cr 2 O 3 oxide layer rich in chromium, and the surface roughness Ra is less than or equal to 0.4 μm.
  3. 3. The H 2 O 2 gas TDLAS analyzer as set forth in claim 1, wherein the mass flow controller is disposed at an air inlet end of the measurement air chamber for controlling a flow of gas into the measurement air chamber, the electronic pressure controller is disposed between an air outlet end of the measurement air chamber and the air pump, and the main control unit is configured to adjust an opening of the electronic pressure controller by a closed-loop PID control algorithm to maintain a constant pressure in the measurement air chamber.
  4. 4. The H 2 O 2 gas TDLAS analyzer according to claim 1 is characterized in that a wind bath constant temperature system consisting of a temperature sensor, a heating block and a fan is further arranged in the heat preservation cabinet, the temperature sensor is connected with the main control unit to form a temperature feedback closed loop, and the main control unit dynamically adjusts the power of the heating block and the rotating speed of the fan through PWM signals.
  5. 5. The H 2 O 2 gas TDLAS analyzer as set forth in claim 4, wherein a interlock protection logic is provided in the main control unit to lock the laser drive module and the pump when the air bath thermostat system does not reach a set temperature.
  6. 6. The H2O2 gas TDLAS analyzer according to claim 1, wherein a ribbed radiator is coupled to a tube shell of the laser, and a PWM speed regulating fan is mounted on the ribbed radiator.
  7. 7. The H 2 O 2 gas TDLAS analyzer according to claim 1, wherein the push-pull circuit is composed of an NPN high-power triode and a PNP high-power triode, an output end of the operational amplifier directly drives an input end of the push-pull circuit, a sampling resistor is connected in series with a cathode of the laser, and voltage signals at two ends of the sampling resistor are used as current feedback signals to be connected to an inverting input end of the operational amplifier.
  8. 8. The H 2 O 2 gas TDLAS analyzer as defined in claim 1, wherein the laser driving module is integrated with a hardware protection circuit including a limiter circuit, a precision current limiting circuit, an over-temperature protection switch, a soft start circuit and a hardware shut-off circuit, wherein the soft start circuit and the hardware shut-off circuit are arranged on a power supply path of the laser.
  9. 9. The H 2 O 2 gas TDLAS analyzer as claimed in claim 8, wherein the laser driving module comprises a driving circuit board, a heat conduction via hole array is arranged at the bottom of a power device on the driving circuit board, an aluminum alloy radiator is mounted on the back of the driving circuit board, a ventilation window is arranged at the corresponding position of the heat preservation cabinet, and an air duct is formed by the ventilation window and the aluminum alloy radiator.
  10. 10. The H 2 O 2 gas TDLAS analyzer according to claim 9, wherein the main control unit is configured with a software protection module, the software protection module is configured to monitor the driving circuit board temperature, the laser package temperature, the working current and the output light power in real time, and when the monitored parameters are over-limited, the software protection module triggers a grading alarm or controls the hardware shutdown circuit to cut off the power.

Description

H 2O2 gas TDLAS analyzer Technical Field The application relates to the technical field of gas concentration detection, in particular to an H 2O2 gas TDLAS analyzer. Background Hydrogen peroxide (H 2O2) is an important industrial oxidizer and disinfectant, and accurate monitoring of gas concentration is important in the fields of semiconductor sterilization, medical instrument sterilization, food packaging safety, and the like. However, H 2O2 gas has strong oxidizing property and instability, and is extremely easy to adsorb and catalytically decompose on the surfaces of sampling pipelines, gas chamber walls and the like, so that the measured value is significantly lower than the true concentration, which is a long-standing problem in the field of 'measuring negative deviation'. In the prior art, tunable semiconductor laser absorption spectroscopy (Tunable Diode Laser Absorption Spectroscopy, TDLAS) technology has been used for detecting various gases (such as NH 3、CO2), but when applied to H 2O2 detection, it faces the following special challenges that 1) gas loss is caused by that common stainless steel or plastic components and optical parts cannot resist H 2O2, and loss is caused by absorption and decomposition of the gases in the transmission process. 2) The TDLAS measurement is based on the beer-lambert law, and the absorption signal intensity is directly affected by factors such as gas temperature, pressure, flow and the like. The traditional analyzer lacks precise control on the internal physical state of the measuring air chamber, so that the measured value fluctuates along with the environment and has poor long-term stability. 3) The problems of thermal management and reliability are that the high-power laser and the driving circuit thereof have large heat productivity, and if the dense heat-generating spots have uneven heat dissipation, the wavelength drift of the laser, the performance degradation of driving components and parts and the thermal stress damage of a circuit board can be caused, so that the long-term reliability of equipment is seriously restricted. 4) The driving performance problem is that the commercial laser driver has difficulty in meeting the requirements of large driving current (> 500 mA), ultra-high modulation bandwidth (> 10 MHz) and extremely low noise required by the Quantum Cascade Laser (QCL) at the same time. The common driving circuit is easy to self-oscillate at high voltage swing rate and high current output, so that the modulation waveform is distorted, and the precision and stability of harmonic detection are directly affected. Therefore, the existing general-purpose TDLAS analyzer is difficult to meet the severe requirements of H 2O2 gas detection on precision, stability and reliability. Disclosure of Invention The application aims to overcome the defects of the prior art and provides an H2O2 gas TDLAS analyzer so as to improve the accuracy, stability and reliability of H 2O2 gas detection. In order to achieve the above object, the present application provides the following. In one aspect, the application provides an H 2O2 gas TDLAS analyzer, which comprises a gas path system, a light path system and a drive control system; The gas path system comprises a sample inlet, a mass flow controller, a measuring air chamber, an electronic pressure controller and an air pump which are sequentially connected through a pipeline, wherein the inner surface of the gas path system contacted with the H 2O2 gas is subjected to inerting treatment to form a chemical inert layer; the optical path system comprises a laser, an optical path comprising the measuring air chamber and a photoelectric detector which are sequentially connected, wherein the optical path system is arranged in the heat preservation cabinet; The driving control system comprises a main control unit and a laser driving module electrically connected with the main control unit, wherein the laser driving module adopts a composite current source architecture and comprises an operational amplifier serving as an error amplifying stage and a push-pull circuit serving as an output stage. Optionally, the inert treatment is electropolishing and super-passivation treatment, and the chemical inert layer is a chromium-rich Cr 2O3 oxide layer with the surface roughness Ra less than or equal to 0.4 mu m. Optionally, the mass flow controller is arranged at the air inlet end of the measuring air chamber and used for controlling the air flow entering the measuring air chamber, the electronic pressure controller is arranged between the air outlet end of the measuring air chamber and the air extracting pump, and the main control unit is configured to adjust the opening of the electronic pressure controller through a closed-loop PID control algorithm so as to maintain the pressure in the measuring air chamber constant. Optionally, a wind bath constant temperature system consisting of a temperature sensor, a heating block and a fan is