Experimental Study Of Oxygen Transport Regularity On Coal Surface Of Lignite During Low-temperature Oxidation

Lignite drying causes the change of coal physical structure,which is bound to affect the migration of oxygen in lignite at low temperature.In this paper,a kind of Indonesian lignite was studied,and the different drying methods and drying degree were used to study the effect of lignite drying on the physical structure of coal samples.For dried coal samples,low temperature oxidation experiments in linear heating and constant temperature two temperature conditions were made,the changing of rule of heat and gas products(CO,CO2)during the oxidation process of coal oxidation were monitored,analysed the effects of the physical structure changes of the coal samples caused by drying to the low-temperature oxidation properties,systematacially studied the influence of drying ways,drying degree to oxygen transport regularity on coal surface during the process of low temperature oxidation.The experimental results show that the number of mesopore of lignite increases with the increase of nitrogen drying strength and then decrease caused by collapse,monotonously decreases with the increase of vacuum drying strength.The maximum number of pores in coal samples with nitrogen content of water content of 6-13% was the highest,and the oxidation rate was the highest at low temperature.During the oxidation process,the formation of the gas product increases with the decrease of particle size and the increase of gas flow rate,but decreases with the decrease of water content.The relationship between the rate of gas generation and the factors affecting the vacuum drying of coal samples is similar to that of raw coal.The low temperature oxidation of oxygen and lignite is mainly controlled by kinetics rather than diffusion.Temperature is an important factor that affects the migration of oxygen.With the increase of oxidation temperature,the oxidation of coal at low temperature becomes more and more serious.The influence of high gas flow rate and high oxygen concentration on the oxidation of lignite at low temperature is similar.The gas flow rate has little effect on the oxidation process of coal samples which means that the change of pore structure has an important influence on the oxygen migration in the low temperature oxidation of lignite.