The product complies with Q/WYH 21-2025 TH-2000 Series Continuous Automatic Monitoring System for Ambient Air Gaseous Pollutants; HJ 654-2013 Technical Requirements and Detection Methods for Continuous Automatic Monitoring Systems of Ambient Air Gaseous Pollutants (SO₂, NO₂, O₃, CO).
Instrument Introduction
The TH-2011 chemiluminescence NOy analyzer adopts gas-phase chemiluminescence principle, utilizing modern microcomputer technology for signal detection, control, and data processing. It integrates optics, mechanics, electronics, photochemistry, and modern sensing technologies to continuously monitor trace concentrations of NO, NOz, and NOy in ambient air. It is one of the high-tech series products for automatic ambient air quality monitoring.
Instrument Principle
Chemiluminescence technology has been used for ambient air monitoring since the 1970s. It has advantages of rapid reaction, strong specificity, and high sensitivity, and is therefore widely used for measuring nitrogen oxide concentrations in ambient air.
Chemiluminescence refers to the luminescence phenomenon accompanying the transition of reaction products from instantaneous high-energy state (unstable) to low-energy state (stable) during chemical reactions. The specific working principle of the chemiluminescence nitrogen oxide analyzer is as follows: Under certain conditions, NO molecules react with O₃ molecules to produce excited-state NO₂ molecules. The reaction equation is: NO + O₃ → NO₂* + O₂; NO₂* → NO₂ + hv (h: Planck's constant; v: emitted photon frequency). The excited-state nitrogen dioxide molecules are highly active and unstable, quickly returning to the ground state. Upon returning to the ground state, they emit photons with wavelengths distributed between 600~3000nm, with maximum radiation intensity near 1100nm. From the above reaction equation, one NO molecule and one O₃ molecule react to produce one NO₂ molecule. In the presence of excess ozone, the intensity of the chemiluminescence reaction is proportional to the NO concentration in the sample cell, and the PMT current output is proportional to the chemiluminescence intensity. Therefore, when the reaction temperature is constant and ozone concentration is in excess, the luminescence intensity is proportional to the NO concentration. Since chemiluminescence occurs only between ozone and nitric oxide, NOy analysis requires reduction of NOy to NO through a reduction furnace (NOy → NO). A set of solenoid switching valves is used to allow NO and gas after the reduction furnace (NOy → NO) to enter the reaction chamber in a time-sharing manner, thereby measuring NO concentration and NOy concentration separately.
Instrument Features
• The instrument adopts a full Chinese menu-style operation interface with touch operation, simplifying the operation procedure.
• Automatic alarm display for quick fault diagnosis.
• Modular building-block design for easy routine maintenance and instrument repair.
• Can simultaneously display measured concentrations of NO and NOy.
• Timely and convenient data acquisition. The instrument forms an automatic monitoring network with other analyzers through RS-232 and RS-485 serial communication ports. Collected data is transmitted to the sub-station via RS-232 or RS-485, and the central station remotely retrieves sub-station data through wired or wireless transmission to timely and effectively grasp the air pollution situation in a certain area, with good timeliness.
• Precise and error-free digital filtering. The analyzer adopts advanced digital filtering algorithm to optimally optimize response time and signal-to-noise ratio based on the minimum mean square estimation error criterion, thereby improving the system's signal-to-noise ratio.
• Remote monitoring. The system adopts modern communication technology. RS-232 and RS-485 interfaces realize data transmission between the instrument and the sub-station host computer as well as automatic monitoring of the instrument by the host computer. Remote data transmission between sub-stations and the central station is realized through software, forming a huge environmental monitoring information network that fully reflects the superiority of modern digital information technology, greatly reducing manpower and material investment, and providing rapid and reliable data guarantee for environmental monitoring departments to analyze and monitor pollution sources.
