关键词: 富氧燃烧, 混煤, 热重分析, 响应曲面法

Abstract: The essay studies on the combustion of blended samples of Xiaolongtan lignite (X), Fuyuan bituminous coal (F) of and Zhaotong lignite (Z) and their combustion characteristics were analyzed by comparing the results of thermogravimetric experiments with different oxygen concentrations and heating rates. The oxygen concentration, heating rate and mass ratio of mixture coal were optimized by applying the optimization software of response surface Design-Expert 8.0.6. The results showed that the temperature of coal ignition and burnout decreased and the combustion time was shorted when oxygen was enriched. When the concentration of oxygen reached the point of 30%(?) the variation of combustion characteristic parameters was minim, so the oxygen concentration in practical application should be controlled around 30%. The activation energy was higher at the later period of pulverized coal combustion, and the activation energy and the pre-exponential factor was increased with the increase of oxygen concentration. Besides, when heating rate grew, the temperature of coal ignition and burnout temperature increased, the burning time was prolonged, while the stability and combustibility was worse. It showed that the coal combustibility improved with the increase of oxygen concentration. The value range of each factor was designed in Criteria of Design-Expert 8.0.6. Set the combustible index and the combustion characteristic index the maximum value and set burnout temperature and investment cost the minimum value, when the mass ratio of Xiaolongtan lignite:Zhaotong lignite:Fuyuan bituminous coal was 100:55.07:1, the four evaluating indicators were relatively optimum, combustibility index was 43.56×10?7, combustion characteristic index was 4.27×10?10, burnout temperature was 680.01℃, cost was 252.49 ￥/t.

Key words: oxygen-enriched combustion, coal blending, thermal gravimetric analysis, response surface methodology