Study On Mechanism Of The Seal Of Power Plant Flue Gas And Its Prevention On Fire

Coal spontaneous combustion seriously affects the safety of coal mining and not only causes the waste of coal resources,but also pollutes the environment.The technology of inert gas preventing fire is effectively used for inerting the goaf and preventing coal spontaneous combustion.Used the power plant flue gas which the main component is nitrogen and carbon dioxide to replace the traditional inert gas can save the cost of generating nitrogen,and also can reduce the emission of greenhouse gas while the power plant flue gas can be absorbed by coal.In this dissertation,used the self-made absorption experimental device of coal,imitated the environment of mine goaf and the composition of flue gas in Tashan Mine Power Plant,the characteristics of coal absorbing flue gas were studied by atmospheric volumetric method,the factors affect the seal of CO2 were analyzed and the effect of power plant flue gas on fire prevention in goaf was investigated at normal temperature and pressure.The experiment results show that the adsorption quantity of Tashan,Tongxin and Gaohai coal were respectively 0.95m3/t,1.0m3/t and 0.84m3/t,the SO2 which came from power plant flue gas could be absorbed entirely by coal.The absorption of coal to N2 and CO2 were physical adsorption at the normal temperature and pressure and the saturation time is 12h,while the absorption of coal to O2 was chemical adsorption and the reaction was failed to reach equilibrium within 228h.When the adsorption coming to 12h,the adsorption quantity of coal to CO2 was about 13～30 times of N2 and 41～58 times of O2.By analyzing the molecular structure and the boiling point of the gas molecules,the result can be obtained that N2 as an inert gas injected into the goaf just can dilute the concentration of O2 in order to inert goaf,while the interaction energy of coal and CO2 is greater than that of O2,so CO2 as an inert gas injected into the goaf not only can dilute the concentration of O2,but also can displace the O2 adsorbed on the surface of coal,thereby fundamentally block the contact of coal with O2.By examining the influence of N2,SO2,H2O and PH to CO2 sequestration,the result can be obtained that N2 can reduce the adsorption capacity of CO2 by 1.4%～2.1%,SO2 can reduce the adsorption capacity of CO2 by 2.3%～3.3%,H2O can reduce the adsorption capacity of CO2 by 2.8%～3.7%,while the change of PH whether increasing or decreasing can increase the adsorption capacity of CO2 by 1.5%～3.8%,and the adsorption capacity of CO2 when the PH is decreasing is obviously larger than the adsorption capacity of CO2 when the PH is increasing.By examining the influence of N2,CO2 and power plant flue gas to O2 adsorption of coal,three kinds of inert gas can also reduce the amount of coal on adsorption of O2,when the power plant flue gas was injected into the goaf,the adsorption capacity of O2 can respectively be reduced by 27%,29%,35%for Tongxin,Tashan,Gaohai coal,while the influence of power plant flue gas to the adsorption capacity and adsorption rate of O2 is between N2 and CO2.The data of thermogravimetric experiment show that the increased weight of coal is less than the coal which was burned in air atmosphere when the three coal was burned in the flue gas atmosphere,while the ignition point is larger than the coal which was burned in air atmosphere.The activation energy curve which was obtained by calculation showed that the activation energy of coal which was burned in the flue gas atmosphere is larger than the coal which was burned in air atmosphere.So the flue gas limits the adsorption of O2 on coal,when the coal is burned in the flue gas atmosphere,the adsorption capacity of O2 on coal is reduced and the activation energy is increased,increasing the difficulty of fire of coal.At present,there is little research for the storage and fire preventing of power plant flue gas.In this paper,the self-made absorption experimental device of coal and TGA is used to study the adsorption property of coal to power plant flue gas at normal temperature and pressure,the results will provide a theoretical support for the technology that power plant flue gas can be sealed into goaf to prevent fire.