A study of the formation of submicron particles in the process of coal combustion and its influencing factors

Through a coal combustion experiment in a sedimentation furnace, the formation mechanism of submicron particles in the process of coal combustion has been discussed along with a study of the influence of furnace temperature, pulverized coal particle diameter and oxygen concentration on the formation of submicron particles. During the experiment, Pingdingshan, Liupanshui and Heshan-origin bituminous coal were chosen by the authors with the pulverized coal particle diameters of each kind ranging from 100 to 200μm, 63 to 100μm and less than 63μm respectively. After the pulverized coal has been burned under different conditions, a 13-stage low-pressure impactor was used to collect inhalable particles in different diameters to perform a study. The research results show that the particles with a diameter of less than 0.377μm are likely to be formed through a gasification-condensation mechanism while the particles with a diameter greater than 0.377μm are formed through a fragmentation and agglomeration mechanism of mineral substances. With an increase of the furnace temperature, a decrease of pulverized coal diameter and an enhancement of oxygen concentration, the amount of submicron particles produced will increase to various extents. The furnace temperature is the most important influencing factor with the pulverized coal diameter and atmosphere playing a secondary role.