| Coal,as one of the most important energies at the present stage in China,has contributed enormously to the country's economic development.However,one problem that cannot be ignored is that coal will be accompanied by five major spontaneous combustion disasters in the process of coal mining.Coal mine fire is one of them and it is in coal mines.In recent years,a large number of scholars at home and abroad are committed to studying the mechanism of low-temperature oxidation of coal.Among them,the coal-oxygen compounding mechanism is the most important hypothesis,and the consumption of coal in the process of low-temperature oxidation Oxygen rate,as an important measure of the oxidation of coal,has been studied by many authors in recent years.Ximeng lignite(XM)was selected as the research object in this paper.Based on industrial analysis and elemental analysis of coal samples,it carries out temperature-programmed and constant-temperature oxidation tests on two different types of coal at low temperatures to try to oxidize coal at low temperatures.The medium oxygen consumption rate model was deduced,followed by discussion of the oxygen consumption rate for a single influencing factor model.Based on the comprehensive analysis,the multi-factor action model for coal oxygen oxidation rate at low temperature was deduced and the following conclusions were obtained:(1)Under the program temperature-raising experimental conditions,for the three single variables selected in the experiment,the oxygen consumption rate of the coal sample,the temperature of the coal sample,the air flow,and the particle size of the coal sample are all the same under other variables unchanged.The rate of oxygen consumption is regular,the first two are exponentially related to the rate of oxygen consumption,and the latter is negatively related to the rate of oxygen consumption.(2)In the coal isothermal oxidation experiment,because the experiment was conducted in a closed tank,there was a critical oxygen concentration in the experiment.The critical oxygen concentration in this experiment was 9.8%.When the oxygen concentration was greater than this critical oxygen concentration,the coal oxidation was rich.Oxygen oxidation states,as the coal-oxygen complex effect progresses,oxygen is gradually consumed,and when the oxygen concentration is lower than this critical oxygen concentration,coal oxidation is in an oxide-rich state.(3)In the isothermal oxidation experiment,before the temperature was 383.15 K,the coal was in the state of oxygen-enriched oxidation.The oxidation time,the oxidation temperature,and the particle size of the coal sample all showed good regularity with the oxygen consumption rate.It has an exponential relationship with the oxygen consumption rate,and the latter has a negative exponential relationship with the oxygen consumption rate.(4)In the isothermal oxidation experiment,after the temperature was 383.15 K,the coal-oxygen complex effect was intensified,the oxygen consumption rate rose rapidly,and the oxygen consumption increased.After reaching the critical oxygen concentration,the oxygen consumption rate began to decline and the coal was oxidized into the oxide-rich state.Under this condition,the oxidation time,oxidation temperature,and the particle size of the coal sample all have regularity with the oxygen consumption rate within the time range from 30 min to 150 min.The former two are exponentially related to the oxygen consumption rate,the particle size of the coal sample are negative exponential relationship with oxygen consumption rate.(5)In the constant temperature oxidation experiment,after the temperature was 383.15 K,when the oxidation time exceeded 150 min,the oxidation time,oxidation temperature,and coal particle size did not show good regularity with the oxygen consumption rate.(6)The model study of oxygen consumption rate in isothermal oxidation experiments can be divided into two stages.The first stage is before the temperature is 383.15 K,the second stage is after the temperature is 383.15 K,and the oxidation time is within 150 min.(7)In the two experiments,the effects of the selected experimental variables on the oxygen consumption rate model are independent.This is because by comparing the model coefficients fitted,it is found that when the coefficients of the two variables are changed,the coefficients are basically the same.constant.(8)In the two experiments,according to the relationship between the oxygen consumption rate and the relationship between the model of each variable and the role of the variables in each experiment,the temperature rise experiment was conducted,and the oxygen consumption rate comprehensive action model was established.A comprehensive model of oxygen consumption rate was established,and the models established were validated.The rationality of the multi-factor comprehensive action model of oxygen consumption rate under different experimental and characteristic experimental conditions was proved. |
PDF Full Text Request