Spontaneous combustion of coal is a major cause of coal mine fires.It not only poses a severe hazard to the safe extraction of coal resources,but also jeopardizes the safety of mine workers.The development of a scient...Spontaneous combustion of coal is a major cause of coal mine fires.It not only poses a severe hazard to the safe extraction of coal resources,but also jeopardizes the safety of mine workers.The development of a scientific management system of coal spontaneous combustion is of vital importance to the safe production of coal mine.This paper provides a comparative analysis of a range of worldwide prediction techniques and methods for coal spontaneous combustion,and systematically introduces the trigger action response plans(TARPs)system used in Australian coal mines for managing the spontaneous heating of coal.An artificial neural network model has been established on the basis of real coal mine operational conditions.Through studying and training the neural network model,prediction errors can be controlled within the allowable range.The trained model is then applied to the conditions of Nos.1 and 3 coal seams located in Weijiadi Coal Mine to demonstrate its feasibility for spontaneous combustion assessment.Based upon the TARPs system which is commonly used in Australian longwall mines,a TARPs system has been developed for Weijiadi Coal Mine to assist the management of spontaneous combustion hazard and ensure the safe operation of its mining activities.展开更多
The effects of three factors on combustion performance of petroleum coke, Herin Coal and Shenmu Coal have been studied, including the ratio of primary air, excess air factor, and the swirling intensity of outer second...The effects of three factors on combustion performance of petroleum coke, Herin Coal and Shenmu Coal have been studied, including the ratio of primary air, excess air factor, and the swirling intensity of outer secondary air. The experiments were carried out on a one-dimensional furnace with dual channel swirling burner, in which temperature of center furnace, emission of air pollutants, and burn-out rate of fuel were measured. The results provide the optimal ratio of primary air, excess air factor and swirling intensity of outer secondary air for the fuels. The combustion performance of petroleum coke B is much better than petroleum coke A, but worse than Hejin coal and Shenmu coal. In addition, the burn-out rate of petroleum coke depends much more on the temperature in terminal stage of combustion than in the early stage of combustion.展开更多
A newly designed strut is proposed in this paper for fuel injection and flame holding in a liquid-kerosene-fueled supersonic combustor. The thickness of the strut is 8ram and the front blockage is about 8%. The charac...A newly designed strut is proposed in this paper for fuel injection and flame holding in a liquid-kerosene-fueled supersonic combustor. The thickness of the strut is 8ram and the front blockage is about 8%. The characteristic of this strut is that extra oxygen can be injected through a set of orifices at the back of the strut, which can change the local flow field structure and ER （Equivalence Ratio）. Based on the above mentioned strut, a stable local flame is generated at the back of the strut and the main combustion can be organized around this local fire. Nu- merical simulation is conducted to compare the local flow field distribution at the back of the strut with/without extra oxygen injection. Experiments are conducted to test the combustion characteristics based on this fuel injec- tion and flame holding strategy. The temperature distribution which can reflect the local flame characteristic has been measured in the experiments conducted under cold incoming supersonic air flow condition. In addition, the overall combustion performance in a full-scale supersonic combustor has been evaluated in the experiments con- ducted under hot incoming supersonic air flow condition. Results show that this strut strategy is very promising since it can organize stable supersonic combustion at the center of the combustor without any cavity or rearward facing step. Besides that, even with the 8ram thick strut, the combustion can be stable in a wide range of ER from 0.25-1 by using liquid room-temperature kerosene.展开更多
A comparative study with kerosene and hydrogen fuel in a model scramjet combustor has been carried out nu- merically. The effect of fuel-air equivalence ratio on the flow field properties in a cavity based mixing mech...A comparative study with kerosene and hydrogen fuel in a model scramjet combustor has been carried out nu- merically. The effect of fuel-air equivalence ratio on the flow field properties in a cavity based mixing mechanism at a freestream Math number of 2.08 has been probed. The investigation has been carried out in a two dimension- al numerical model where a cavity of length to depth ratio of 2 is mounted on one of the walls of the flow channel The flow field shock structure is observed to change with the change in fuel-air equivalence ratio. Total pressure loss is observed to depend both on fuel air equivalence ratio and the fuel type. The spread of fuel in the test sec- tion shows marked variation with the equivalence ratio. Performance of injector location on the fuel-air mixing is also probed during the course of the investigation.展开更多
基金provided for this work by the China Scholarship CouncilNational Natural Science Funds of China(No.51304212)
文摘Spontaneous combustion of coal is a major cause of coal mine fires.It not only poses a severe hazard to the safe extraction of coal resources,but also jeopardizes the safety of mine workers.The development of a scientific management system of coal spontaneous combustion is of vital importance to the safe production of coal mine.This paper provides a comparative analysis of a range of worldwide prediction techniques and methods for coal spontaneous combustion,and systematically introduces the trigger action response plans(TARPs)system used in Australian coal mines for managing the spontaneous heating of coal.An artificial neural network model has been established on the basis of real coal mine operational conditions.Through studying and training the neural network model,prediction errors can be controlled within the allowable range.The trained model is then applied to the conditions of Nos.1 and 3 coal seams located in Weijiadi Coal Mine to demonstrate its feasibility for spontaneous combustion assessment.Based upon the TARPs system which is commonly used in Australian longwall mines,a TARPs system has been developed for Weijiadi Coal Mine to assist the management of spontaneous combustion hazard and ensure the safe operation of its mining activities.
基金Acknowledgments This work is supported by Natural Science Foundation of China （NO. 51076127） and the Clean Combustion ＆ Gas-solid Two-Phase Flow group in Xi＇an Jiaotong University.
文摘The effects of three factors on combustion performance of petroleum coke, Herin Coal and Shenmu Coal have been studied, including the ratio of primary air, excess air factor, and the swirling intensity of outer secondary air. The experiments were carried out on a one-dimensional furnace with dual channel swirling burner, in which temperature of center furnace, emission of air pollutants, and burn-out rate of fuel were measured. The results provide the optimal ratio of primary air, excess air factor and swirling intensity of outer secondary air for the fuels. The combustion performance of petroleum coke B is much better than petroleum coke A, but worse than Hejin coal and Shenmu coal. In addition, the burn-out rate of petroleum coke depends much more on the temperature in terminal stage of combustion than in the early stage of combustion.
基金supported by National Natural Science Foundation of China(No.90816028)National Science Fund for Distinguished Young Scholars of China(No.50925625)
文摘A newly designed strut is proposed in this paper for fuel injection and flame holding in a liquid-kerosene-fueled supersonic combustor. The thickness of the strut is 8ram and the front blockage is about 8%. The characteristic of this strut is that extra oxygen can be injected through a set of orifices at the back of the strut, which can change the local flow field structure and ER （Equivalence Ratio）. Based on the above mentioned strut, a stable local flame is generated at the back of the strut and the main combustion can be organized around this local fire. Nu- merical simulation is conducted to compare the local flow field distribution at the back of the strut with/without extra oxygen injection. Experiments are conducted to test the combustion characteristics based on this fuel injec- tion and flame holding strategy. The temperature distribution which can reflect the local flame characteristic has been measured in the experiments conducted under cold incoming supersonic air flow condition. In addition, the overall combustion performance in a full-scale supersonic combustor has been evaluated in the experiments con- ducted under hot incoming supersonic air flow condition. Results show that this strut strategy is very promising since it can organize stable supersonic combustion at the center of the combustor without any cavity or rearward facing step. Besides that, even with the 8ram thick strut, the combustion can be stable in a wide range of ER from 0.25-1 by using liquid room-temperature kerosene.
基金supported by Advanced Research Center Program(No.2013073861) through the National Research Foundation of Korea
文摘A comparative study with kerosene and hydrogen fuel in a model scramjet combustor has been carried out nu- merically. The effect of fuel-air equivalence ratio on the flow field properties in a cavity based mixing mechanism at a freestream Math number of 2.08 has been probed. The investigation has been carried out in a two dimension- al numerical model where a cavity of length to depth ratio of 2 is mounted on one of the walls of the flow channel The flow field shock structure is observed to change with the change in fuel-air equivalence ratio. Total pressure loss is observed to depend both on fuel air equivalence ratio and the fuel type. The spread of fuel in the test sec- tion shows marked variation with the equivalence ratio. Performance of injector location on the fuel-air mixing is also probed during the course of the investigation.
