석탄 연소기술에서 타 연소로에 비해서 유동층 연소는 황산화물과 질소산화물 배출을 줄이는 기술이다. 석회석의 소성으로 생성되는 CaO에 의한 황산화물의 제거와 저온 연소와 공기 다단계 주입에 의한 NOx를 줄일 수 있다는 것이 유동층 연소로의 큰 장점이지만, 상대적으로 N2O의 배출은 매우 높다. N2O는 지구온난화 가스일 뿐만 아니라 성층권내의 오존층을 파괴하는 물질이기도 하다. CaO는 N2O 분해를 위한 촉매 물질로 알려져 있다. 본 연구는 CaO를 충진시킨 고정층 반응기에서 CaO에 의한 N2O의 분해특성에 관하여 수행하였으며, 유동층 연소온도와 가스조성에서 온도변화에 대한 N2O의 분해특성, CaO 충진량의 변화와 CO2, NO, O2 농도변화에 따른 N2O 분해특성에 관하여 수행하였다. 또한 실험 결과로부터 CaO표면에서 N2O분해반응에 대한 반응속도식을 나타낼 수 있었다. 결과로서 온도가 증가함에 따라 N2O 분해반응이 증가하였으며, CO2의 농도를 변화시킬 경우 CO2 농도가 증가할수록 N2O 분해반응이 감소하였다. NO 존재시와 비교하였을 때 N2O의 분해반응이 감소함을 알 수 있었다. 반응속도론적으로 해석한 결과 CO2 농도에 대한 N2O 분해반응의 반응속도식을 다음과 같이 나타내었다. 본 연구 결과 CaO는 N2O분해 반응에서 좋은 촉매 기능을 지니고 있음을 알 수 있었다._x000D_ d[N2O]/dt=3.86×10(9)exp(-15841/R)KN2O[N2O]/(1+KN2O[N2O]+KCO2[CO2])

Fluidized bed combustion is a coal combustion technology that can reduce both SOx and NOx emission; SOx is removed by limestone that is fed into the combustion chamber and the NOx is reduced by low temperature combustion in a fluidized bed combustor and air stepping, but N2O generation is quite high. N2O is not only a greenhouse gas but also an agent of ozone destruction in the stratosphere. The calcium oxide(CaO) is known to be a catalyst of N2O decomposition. This study of N2O decomposition reaction in fixed bed reactor packed over CaO bed has been conducted. Effects of parameters such as concentration of inlet N2O gas, reaction temperature, CaO bed height and effect of CO2, NO, O2 gas on the decomposition reaction have been investigated. As a result of the experiment, it has been shown that N2O decomposition reaction increased with the increasing fixed bed temperature. While conversion of the reaction was decreased with increasing CO2 concentration. Also, under the present of NO, the conversion of N2O decomposition is decreased. From the result of kinetic study gained the heterogeneous_x000D_ reaction rate on N2O decomposition. In the case of N2O decomposition over CaO, heterogeneous reaction rate is. d[N2O]/dt=3.86×10(9)exp(-15841/R)KN2O[N2O]/(1+KN2O[N2O]+KCO2[CO2]). In this study, it is found that the calcium oxide is a good catalyst of N2O decomposition.

Nitrous oxide decomposition CFBC CaO CO2 SOx

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