The efforts of the world research activities involved in clean coal technologies development focus to a considerable extent on integrated hydrogen and power generation technologies based on coal gasification.As an alt...The efforts of the world research activities involved in clean coal technologies development focus to a considerable extent on integrated hydrogen and power generation technologies based on coal gasification.As an alternative to combustion pro-cesses,gasification offers increased efficiency,lower negative environmental impact as well as wider application range of the main product—synthesis gas—in power generation and chemical syntheses.In order to select the most optimal lignite for the purpose of gasification,it is necessary to determine coal reactivity,the key parameter characterizing how fast the fuel reacts with the gasifying medium and controlling its process ability in thermochemical conversion to energy and/or energy carriers.This paper presents the experimental results of oxygen/steam gasification of lignite coal char in a fixed bed reactor under atmospheric pressure and at the temperature of 700,800 and 900℃;the samples come from an open pit lignite mine in the southwest of Poland.The effectiveness of the gasification process was tested in terms of the total gas and hydrogen yields,gas composition,carbon conversion rate and chars reactivity.展开更多
The purpose of this study was to develop a physico-mathematical model and technique for estimation of chemical bond stability depending on electric field intensity of an external point charge.A hypothesis for a possib...The purpose of this study was to develop a physico-mathematical model and technique for estimation of chemical bond stability depending on electric field intensity of an external point charge.A hypothesis for a possible physico-chemical mechanism of the formation of additional harmful gases in the rock destruction by blasting was proposed.The theoretical basis of the hypothesis is the method of theretical evaluation of bond energy depending on the distance to a point charge,the third Coulomb centre.The quantum-mechanical model for calculating the electronic terms of molecules makes it possible to solve problems associated with the determination of parameters of molecules under the action of various physical fields on the system under consideration.The model was approved for some diatomic molecules.The discrepancy between the experimental data and calculated data did not exceed 14%,which proves accuracy of the obtained results.The model can be used in the field of research into the causes of gas-dynamic phenomena in underground coal mines,in studies of the degree of stability of nanostructured components of coal under physical influences,and in the theoretical design of new compounds and structures in the field of nanomaterial science and nanotechnology.展开更多
The flow velocity of gases in gobs directly influences the kinetics and intensity of gaseous components release during heating and cooling of coal.The assessment of fire hazard is performed on the basis of concentrati...The flow velocity of gases in gobs directly influences the kinetics and intensity of gaseous components release during heating and cooling of coal.The assessment of fire hazard is performed on the basis of concentrations of particular gases in a mine air.These concentrations differ in coal heating and cooling phase which was proven in the study.This paper presented the results of the experimental study on temperature distribution in a simulated coal bed in heating(50–250°C)and cooling(250–35°C)phases as well as its correlation to variations in concentration of gases released in these phases and flow rates of gases flowing through the coal bed.The research was performed on twenty-two samples of bituminous coals acquired from various coal beds of Polish coal mines.Considerable differences were observed between heating and cooling phases in terms of the concentrations of gases taken into account in calculations of self-combustion index.In the heating phase temperature increase resulted in the decrease of concentrations ratios of ethane,ethylene,propane,propylene and acetylene,while in the cooling phase these ratios increased systemically.The effect of air(in heating phase)and nitrogen(in cooling phase)flow rate on the self-ignition index CO/CO2 was also determined.展开更多
文摘The efforts of the world research activities involved in clean coal technologies development focus to a considerable extent on integrated hydrogen and power generation technologies based on coal gasification.As an alternative to combustion pro-cesses,gasification offers increased efficiency,lower negative environmental impact as well as wider application range of the main product—synthesis gas—in power generation and chemical syntheses.In order to select the most optimal lignite for the purpose of gasification,it is necessary to determine coal reactivity,the key parameter characterizing how fast the fuel reacts with the gasifying medium and controlling its process ability in thermochemical conversion to energy and/or energy carriers.This paper presents the experimental results of oxygen/steam gasification of lignite coal char in a fixed bed reactor under atmospheric pressure and at the temperature of 700,800 and 900℃;the samples come from an open pit lignite mine in the southwest of Poland.The effectiveness of the gasification process was tested in terms of the total gas and hydrogen yields,gas composition,carbon conversion rate and chars reactivity.
基金The studies were accomplished within the framework of the project"Investigation of coal nanostructure as a source of coal mine methane"with a financial support of the Ministry of Education and Science of Ukraine according to the Order No.199 of February 10,2017.
文摘The purpose of this study was to develop a physico-mathematical model and technique for estimation of chemical bond stability depending on electric field intensity of an external point charge.A hypothesis for a possible physico-chemical mechanism of the formation of additional harmful gases in the rock destruction by blasting was proposed.The theoretical basis of the hypothesis is the method of theretical evaluation of bond energy depending on the distance to a point charge,the third Coulomb centre.The quantum-mechanical model for calculating the electronic terms of molecules makes it possible to solve problems associated with the determination of parameters of molecules under the action of various physical fields on the system under consideration.The model was approved for some diatomic molecules.The discrepancy between the experimental data and calculated data did not exceed 14%,which proves accuracy of the obtained results.The model can be used in the field of research into the causes of gas-dynamic phenomena in underground coal mines,in studies of the degree of stability of nanostructured components of coal under physical influences,and in the theoretical design of new compounds and structures in the field of nanomaterial science and nanotechnology.
基金This work was supported by the Ministry of Science and Higher Education,Poland(No.14303018).
文摘The flow velocity of gases in gobs directly influences the kinetics and intensity of gaseous components release during heating and cooling of coal.The assessment of fire hazard is performed on the basis of concentrations of particular gases in a mine air.These concentrations differ in coal heating and cooling phase which was proven in the study.This paper presented the results of the experimental study on temperature distribution in a simulated coal bed in heating(50–250°C)and cooling(250–35°C)phases as well as its correlation to variations in concentration of gases released in these phases and flow rates of gases flowing through the coal bed.The research was performed on twenty-two samples of bituminous coals acquired from various coal beds of Polish coal mines.Considerable differences were observed between heating and cooling phases in terms of the concentrations of gases taken into account in calculations of self-combustion index.In the heating phase temperature increase resulted in the decrease of concentrations ratios of ethane,ethylene,propane,propylene and acetylene,while in the cooling phase these ratios increased systemically.The effect of air(in heating phase)and nitrogen(in cooling phase)flow rate on the self-ignition index CO/CO2 was also determined.
