The Effect of Air Distribution Modes and Load Operations on Boiler Combustion

Abstract

This paper presents part of the UK Royal Academy of Engineering sponsored research which is concerned with reducing air pollution from coal-fired power station in Northeast of China. It is still commonly accepted that the primary structure of energy production and consumption in North Cities of China mainly based on coal combustion will remain no change in the next decade. Therefore, how to improve the thermal efficiency of boilers and reduce the emission of nitrogen oxides has always directed the research of coal production personnel and researchers. To solve above problems, this paper takes a 200 MW four-corner tangential boiler of a power plant as the research object. Based on the study of different methods of air distributing, the adjustment of different tertiary air, variable load and different air distribution of secondary air were discussed. On the basis of the former, the secondary air in DE and EE layers was replaced by tertiary air, and a three-layer separated exhaust air was added to the upper part of the compact exhaust air. Finally, by comparing the results of combustion numerical simulation with the actual measurement of  nitrogen oxides, it can be concluded that the concentration of NO molar fraction is the lowest when no coal mill is put into operation, followed by one coal mill and the highest when two coal mills are put into operation.