Atmospheric Nitrogen Oxide Chemiluminescence Detection Theory And On-line Monitoring Instruments

Pollution is one of the serious problems with the progress of industrialization. Atmosphere pollution is the worst to human being. We can't stop breathing for a clock. In recent years, NO\ (NO & NO2) is gradually becoming the primary pollutant in atmosphere because the number of motor is rapidly increasing. NOx can conduce photochemical smog, which do much harm to our health.The monitoring of atmosphere quality is the guide of atmosphere pollution prevention and cure. An atmosphere quantity monitor network with appropriate distribution and rapid reaction in city area is an important ensurance for atmosphere pollution prevention and cure. But at present NOx analyzers for monitoring of atmosphere quality in our country is almost all imported. The price and maintenance of the imported analyzer is too high to make them widely used, which serious affects the process of atmosphere pollution prevention and cure. Hence, Environmental Protection Agency of Guangzhou seted up the project of "Domestical Research & Production of NOx Auto-Monitoring System for Atmosphere Quantity Monitor " which is undertaken by our laboratory.This paper is the sum-up of the preliminary achievement of the project. After several methods for NOx detection is briefly intruduced the principle of chemiluminesce ( CL ) for NO detection is emphasized in the paper. The Photon-Count method formula for NO NO detection based on the principle of CL is deduced and the system parameters which can influence the detection sensitivity are analyzed in detail.The technology specific of the NO detection system based on CL that we developed and the important parts in the system such as Reaction Chamber, Ozonator is introduced in the paper.After a series of experiments were carried out regularities are found as follows:(1) In the range of 38~62癈, the detection sensitivity increases with the reaction chamber;(2) The detection sensitivity reachs its peak when the pressure of reaction chamber is around 0.086 M Pa.(3) The detection sensitivity reachs its peak when the ozone flow is 0.3 LPM and the span flow is 1 .6 LPM.Then we adjusted the system to a good state and carried out the experiment to test the linearity relation between the output cout rate and NOconcentration. And we got a good linearity relation plot. The linearity range is 45~3500ppb by conservatively estimate and can likely be extended to the low concentration below 45ppb.Based on the data from the experiment to test the linearity relation we have give the syetem a preliminary evaluation. The result is the detection range of the system is 45~3500ppb and if linearity range can be extended to the low concentration below 45ppb the system will have the capability to detect NO at 2ppb concentration. The system has great potential. If the ozonator is improved the system's performance can be improved much more.The theory analysis, design and manufacture, experimental achivement above provides relaible technical base.