| Researching on the NOx, which is one of the air pollutants, and putting focus on optimizing the power plant SNCR technique in coal-based boiler, this essay studied at a power plant with flowing rate of 410t/h. Firstly, a brief definition of selective non-catalytic reduction (SNCR), selective catalytic reduction (SCR), and SNCR-SCR hybrid technique had been introduced. Moreover, the working principle, technological progresses and operating system of these three techniques has been well compared and analyzed. The boiler in a power plant of 410t/h class without any NOx reduction facility would have a NOx emission level of 350mg/m3. However, adding with SNCR would reduce this emission level to 200mg/m3, and the data collected from the SNCR in the routine experiment could also assist the boiler keeping a stable operation. Furthermore, as the requirement of environment protection improved recently, this power plant improved the NOx reduction technique from SNCR to SNCR-SCR hybrid and reduced the NOx emission under the level of 100mg/m3. The working principle of SNCR-SCR is using urea solution as the reducer, adding a tail steam disturbance system and modifying the lord of boiler, combustion condition, flowing rate of nozzle and the concentration of urea, to have the initial experiment. At the meanwhile, the experiment result could make the operation method be optimized that the efficiency of SNCR-SCR hybrid operation could be improved, the escape rate of ammonia could be reduced and the pollutant emission can be well controlled. This essay is basing on the experimental data, had summarized a reasonable operation method and furthermore put forward a more environment-friendly adjustment suggestion, and with analyzing the influence of the whole power plant through adding SNCR-SCR hybrid NOx reduction system into such system to put forward several solutions to the problems such as solving the boiler water cooled wall corrosion and boiler cold ash hopper bottle slag blow off jam. |
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