Experimental Study On SNCR Flue Gas Denitrification Technology

Studying on dry NOx removal by SNCR (Selective Non-Catalytic Reduction) was carried out in this thesis, which is adopted by the developed countries at large now. It is a mature technology for moderate NOx emission control on fluegas. Its investment and operating cost are lower than other flue gas de-NOx techno-logies, and the installation is easy relative to other NOx emission control technologies. So SNCR is suited for retrofitting the smaller utility boiler,and suited to China's national situation.In this paper, we explored theory of formation and control of NOx at first, and then compared different kinds of control methods. Through experiment, we studied the effect of different methods to control the emission of NOx. The experimental setting of CRF(Combustion Research Facility) had been constructed, on which the experimental study on methods of SNCR was carried out. Studying on the several factors influncing NOx removal efficiency by SNCR was done. The key factors influencing NOx removal efficiency by SCR mainly include: tempe-rature, NH3/NO molar feed ratio, reducing agent etc. The experimental result showed that temperature and NH3/NO molar feed ratio influence the NOx remo-val efficiency in evidence. The NOx removal efficiency is rising with the increase of NH3/NO molar feed ratio. The optimal temperature for injected aqueous urea is 850℃-950℃, NH3/NO molar feed ratio should between 1.0 and 2.0, the optimal concentration of urea in aqueous urea is 10%. Compared the aqueous urea with ammonia, urea is found to give the higher NOx removal efficiency and easy to transit. Studying on the ammonia slip was also done, the curve of ammonia slip showed that the ammonia slip is increased with the increasing of NH 3 /NO molar feed ratio. At NH 3/NO molar feed ratio between 1.0 and 2.0, 900℃and by using urea reductant, 65.3%-84.2% NO removal are obtained, and the concentration of ammonia slip is below 10ppm.Finally, some existed problems and solution were analyzed. The development trend was prospected.