Experimnetal Study Of Characteristics Of Nitrogen Oxide Formation For Different Kinds Of Coals Burning In A Drop Tube Furnace

NOX, which formed during the process of pulverized coal burning, are much harmful to people's health. Furthermore, they will pollute the environment greatly. As people pay more attention to environment protection, it, is an important task that people control the emission of NOX and study the theory of combustion of pulverized coal for low NOX emission in the field of pulverized coal burning.This paper studied high-temperature pyrolysis of three coals: Huainan bituminous > Zhengzhou sub-bituminous and Jincheng anthracite in a drop tube furnace. The factors were temperatures ^ residence times in the furnace and volatile of coals. And different effects of these factors on the emission of NOX pre-cursors HCN and NHs during pyrolysis ^ porosity of chars and conversion of nitrogen have been studied in this paper.At the same time, eight kinds of coals were burned in the drop tube furnace under different temperatures of hearth, coefficients of excess air temperatures of second ah% ratios of first air, second air and total quantity of coal feeding into furnace. The concentrations of NO were measured at the bottom of the furnace. This paper has studied effects of these factors on the characteristics of NO formation in the furnace.At last, this paper has built a mathematical model of NO formation during the combustion of volatiles which are from a single coal particle. Two models of devolatilization, two equations model and Fu-Zhang universal model, have been adopted to describe the process of devolatilization. The results of the two models have been compared and also verified with the results of the pyrolysis experiments. The mathematical model has been used to study the different effects of temperature of hearth, the oxygen and the diameter of a coal particle on porosity of coal and conversion of nitrogen.