Experimental and Numerical Study on Co-combustion Behaviors and NO_(x) Emission Characteristics of Semi-coke and Coal in a Tangentially Fired Utility Boiler  

作　　者：WANG Chang’an FENG Qinqin JIN Liyan WANG Zhichao YAO Wei WANGPengqian DU Yongbo ZHANG Xilai YANG Zhongcan CHE Defu 

机构地区：[1]State Key Laboratory of Multiphase Flow in Power Engineering,School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China [2]Xi’an Thermal Power Research Institute Co.,LTD.,Xi’an 710054,China

出　　处：《Journal of Thermal Science》2021年第4期1116-1131,共16页热科学学报（英文版）

基　　金：financial support from the National Key R&D Program of China (2017YFB0602003)。

摘　　要：The utilization of powdery semi-coke as a power fuel in pulverized coal-fired power plants has become a new and potential technique to consume the excess powdery semi-coke.The characteristic of low volatile results in poor combustion performance and high NO_(x) emission,and to co-fire with bituminous coal is a practical strategy to address this problem.However,the co-combustion characteristics and the inherent interaction between semi-coke and coal remain insufficiently understood.In addition,the influences of secondary air arrangement,the boiler operation load,and the fuel type on co-combustion process are still unclear,which is urgent to be further explored.In the present study,experiments and numerical simulations were jointly utilized to inquire into the co-combustion behaviors and NO_(x) emission features of semi-coke and coal.The results demonstrated that the"out-furnace method"was a suitable choice for small-capacity boiler when the proportion of semi-coke was 33%,due to the limited combinations of the semi-coke injection position.It was recommended that semi-coke was preferred to be injected from the middle layers of the furnace under the"in-furnace method"to improve the overall co-combustion performance.The critical value of the separated over fire air ratio in this study was 27.5%,over which a slight drop of carbon content in fly ash could come about.Moreover,the elevation in the proportion of separated over fire air gave rise to the significant decline of NO_(x) concentration.The constricted secondary air arrangement was preferred to be employed due to the high boiler efficiency.The separated over fire air and the surrounding air needed to maintain a wide-open degree to prevent the increase of NO_(x) emissions and the coking of nozzles.For the load reduction regulation method adopted in this study,the NO_(x) concentration first rose and then dropped,while the burnout ratio decreased obviously as the operation load was reduced.Different combinations of coal and semi-coke generated significant influences

关 键 词：SEMI-COKE numerical simulation CO-COMBUSTION NOx emission blending method 

分 类 号：X773[环境科学与工程—环境工程]