The Study On Elimination Efficiency For NO_x In Tunnels With The Soil Matrix

Pollution on nitrogen oxide (NOx) gas in the emission of automobile exhaust has already seriously affected the atmospheric environment and the quality of life of the people。To the status quo of the pollution on NOx, based on the independent innovation subject-"soil purification technology research on highly concentration air pollution in tunnel of road"of Chongqing Traffic research Design Institute, at Zhenwu Mountain Tunnel, using the soil purification technology, purificating NOx in the polluted air conducted a preliminary study on the site。In this study, five kinds of ratio on soil matrix were formulated initially, and the soil matrix having been rated was packed in the soil columns separately, watering on time, accessing to the polluted air, after 10 days of stable running, studied separately the ratio and materials of soil matrix。By analysing, the best ratio of the soil matrix was determined that is humus to perlite to peat being 3 to 1 to 1。Basing on this ratio, we investigated separately the relations of inlet concentration,inlet air line speed,gas temperature,gas relative humidity,material temperature,material relative humidity,system pressure and the purification rate on NOx in the polluted air。The results shows: on the purification of NOx in polluted air in the tunnel, the ratio of soil matrix-humus to perlite to peat being 3 to 1 to 1-is superior to other materials and ratio。If other conditions being certain ,the purification rate of NOx is wholly more than 90%, outlet concentration of NOx is wholly lower than 200PPB, the design requirements are fully meet。With time leaving, the purification of NOx declines gradually。Unchanging other conditions,inlet concentrations between 1921-2588PPB or system pressure between 0-1cm,NOx removal rate changs little;inlet linear velocity between 0.32-0.38mm/s, NOX removal rate is relatively stable, between 0.38-0.52mm/s,NOX removal rate changes in large, the higher the inlet velocity, the lower NOx removal rate of;gas temperature between 8-15.C or the filler temperature between 9.8-19.C,the higher the temperature, the lower NOx removal rate; gas relative humidity between 81-88% or the filler relative humidity between 37-64%, the higher the humidity, the higher NOx removal rate, gas relative humidity between 88.5-94% or filler relative humidity between 58-66%, the higher the humidity, the lower NOx removal rate, too high or too low relative humidity is not conducive to remove NOx。...