燃煤过程中亚微米颗粒生成及影响因素的研究

A Study of the Formation of Submicron Particles in the Process of Coal Combustion and Its Influencing Factors

通过沉降炉燃煤实验,讨论了燃煤过程中亚微米颗粒的形成机理,研究了炉膛温度、煤粉粒径及氧浓度对亚微米颗粒生成的影响。实验选择平顶山烟煤、六盘水烟煤和合山烟煤,每种煤的煤粉粒径范围分别是100-200μm、63-100μm和小于63μm。煤粉在不同条件下燃烧后,用13级低压撞击器按不同粒径收集可吸入颗粒物进行研究。结果表明：粒径小于0.377μm的颗粒是通过气化—凝结机理形成,而粒径大于0.377μm的颗粒是通过矿物质的破碎、聚结机理形成;随着炉膛温度的升高、煤粉粒径的降低及氧浓度的提高,亚微米颗粒生成量会有不同程度的增加;炉膛温度是最主要的影响因素,煤粉粒径及气氛次之。

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 200 μm, 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 0.377 μm are likely to be formed through a gasification-condensation mechanism while the particles with a diameter greater than 0.377 μm 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.