EXPERIMENTAL STUDY ON NOz EMSSION IN PF BOILER WITH HORIZONTAL BIAS COMBUSTION BURNER AND OVER-FIRE AIR SYSTEM
IntroductionNitric oxides (NOx) have been identified as direct precursors of photochemical smog and linked to acid rain 1. Generally, nitric oxides include NO, N2O and NO2. However, the percentage of N2O and NO2 are much less than NO in Nox emission. NO is the major composition of Nox, and as the source of NO emission, it can be subdivided into three categories: prompt-NO, thermal-NO, and fuel NO 2-4. Compared to thermal NO, the prompt NO amount formed is only a weaker function of temperature, and it shows a maximum at fuel-rich conditions, and contributes a relatively minor fraction of total Nox emissions for coal-fired boilers 1. Thermal-NO can be controlled by increasing the size of the combustion zone for a given thermal input and reducing the rate of combustion and peak flame temperatures with specially designed burners. The size of the combustion zone may be increased by using an over-fire air (OFA) system with an existing boiler or by increasing the furnace dimensions in the burner area for a new boiler 5. Fuel Nox formation can be reduced by switching to, or co-firing with, fuel with lower nitrogen content and/or by limiting oxygen availability during the early stages of combustion. Methods for reducing oxygen availability include lowering the excess air level and/or controlling the ratio at which the fuel and air mix (I.e., staging the combustion process) 2. The effects of staged-air combustion on Nox emission, the thermal efficiency, the unburned carbon in fly ash and temperature in coal-fired furnace were studied in this study, where the staged-air combustion is realized by horizontal bias combustion burner, over-fire air (OFA) system and the different secondary air distributions.
Jun Fei Rui Sun Xiang Liu Junfeng Lu Yufang Wu
Combustion Engineering Research Institute, Harbin Institute of Technology, Harbin, 150001, China
国际会议
The 7th China-Korea Workshop on Clean Energy Technology(第七届中韩清洁能源技术研讨会)
太原
英文
215-216
2008-06-25（万方平台首次上网日期，不代表论文的发表时间）