石灰石脱硫对循环流化床锅炉现场试验中N2O排放的影响研究

Effect of limestone desulfurization on N2O emission in CFB boiler fieldtest

以往对于石灰石脱硫过程中N2O排放特性的研究多集中在机理和实验室研究方面,在现场进行实际测量的数据较少。为了探索现场试验中石灰石脱硫对循环流化床(CFB)中N2O排放的影响,测量和分析了某150 MW CFB锅炉不同负荷下炉内石灰石脱硫对烟气中SO2、N2O和NOx的影响规律。结果表明:投入石灰石后,SO2排放质量浓度在短时间内从1 200 mg/m^3下降到100 mg/m^3以下;石灰石以一定速率给入时,N2O排放质量浓度会一定程度地降低,这与CaO对N2O的热催化作用相关,但NOx排放质量浓度显著升高,呈现此消彼长趋势;随着锅炉负荷的升高,N2O排放质量浓度整体出现下降趋势。在CFB的燃烧温度范围内,N2O可能取代NOx作为主要的氮氧化物污染物来源。

Researches on N2O emission characteristics in limestone desulfurization process in the past few years mainly focused on mechanism and laboratory research,while the data measured in the field was rare.In order to explore the influence of limestone desulfurization on N2O emission mass concentration in circulating fluidized bed(CFB) fieldtest,the variation trend of SO2,N2O and NOx in flue gas of boiler at different loads was comprehensively measured and analyzed after limestone was put into the 150 MW CFB unit for desulfurization.The results show that,the SO2 emission mass concentration reduced from 1 200 mg/m^3 to below 100 mg/m^3 in a short time.When the limestone was fed at a certain rate,the N2O emission mass concentration decreased to some extent,which was related to the catalytic effect of CaO on the thermal decomposition of N2O.However,the NOx emission mass concentration increased significantly.With the increase of boiler load,the N2O emission mass concentration decreased as a whole.Within the combustion temperature range of CFB boilers,N2O is likely to replace NOx as the main source of pollutants.