Research On The Technology And Key Equipments For Dust Removal And Denitrification In City Tunnel

Currently, the air pollutants generated from automobile exhaust have become increasingly severe owning to the rapid growth of car ownership. The amounts and lengths of tunnels in city are also growing rapidly due to the extensive expansion of city and the increase in traffic demands. The city tunnel, which is an enclosed space where the air pollutants are difficult to be ventilated, would result in a gradual accumulation of particulate matter (PM) and nitrogen dioxide (NO2) as emitted from the vehicles. This has seriously influenced the environment inside the city tunnel and impaired the health of drivers and surrounding residents. In this thesis, the application of dust removal and denitrification technologies as well as their key equipments for city tunnel were studied. We expected that the work conducted herein could provide a theoretical basis for the design of air pollutants control in city tunnels.Firstly, after comprehensive comparison and analyses on the current air purification technologies for city tunnels, we had selected a combined electrostatic precipitation and adsorptive denitrification technology as an efficient and economically feasible route for typical air pollutants (i.e. PM and NO2) removal in city tunnels.Secondly, a typical city tunnel that was 3000 m in length was chosen for the design of combined dust removal and denitrification technology. The air volume for dust removal and denitrification in the tunnel was calculated at 250 m3/s based on the air volume for diluting CO and smog. A bypass channel, as the place for dust removal and denitrification equipments installation, was set up at ca.1832 m away from the tunnel entrance.Thirdly, based on the air volume of 250 m3/s, the lectotype of equipments with an aim to achieve the goal of 80% dust removal and 90% denitrification efficiencies was evaluated, together with the best operation condition and a design proposal being established. The operation cost for dust removal and denitrification in city tunnel was evaluated according to the runtime of 14 h/d, where the economic analysis was also conducted accordingly.Finally, in order to compensate the current dust removal and denitrification technology in city tunnels, a mobile car, which is simple in structure, comprehensive in function, easy to be operated and low in cost, was preliminarily designed for the collection of particulate matter (PM) and the adsorption of nitrogen dioxide (NO2).