Research On Radon Concentration Distribution Of Ground Surface In The Process Of Underground Coal Gasification In Ulanchap

Underground coal gasification(UCG)is to make underground coal resources directly into CH4?CO and other flammable gases as the like through making coal resources into combustion directly underground,leaving ash behind.As a new type of coal mining method,UCG compared with traditional coal mining method has not only improved the security of the coal mining staff,but it has also reduced bad impacts on the environment.Considering the coal seam with a burial depth of 270 meters in Ulanchap,to monitor the position and extent of burning zone will play a vital role in the realization of the control of underground coal gasification combustion.Based on the corpus "Integrated detection technology of UCG working face"subordinate to the major research project------national "863" plan "key technology of industrialization of underground coal gasification"(Project Number:2011 aa050102),this paper has designed a all-weather radon measurement sampling device suitable for the Ulanchap area,applying the activated carbon radon measurement method into monitoring work.The study is conveyed lasting from normal stage to pressurized stage,and finally to gasification stage so as to analysis the distribution of radon concentration.In order to obtain the distribution of radon in pressurization stage and gasification stage,the distribution of radon under the natural condition has been studied.Research shows that:the all-weather radon gas sampling device will cause a disturbance in the shallow surface,and there will be a balancing process after that.After the balancing process,the radon distribution is related mainly to medium of surface shallow,topography,meteorological factors,and also to the frequent engineering activities.Based on the study stated above,the radon distribution in deep underground in the pressurization stage is analyzed from the average radon concentration curve,horizontal profile(vertical to the drilling direction)and plane distribution map.Due to the frequent engineering activity in No.1 area in gasification stage,the study is focused on radon in No.3 area.The radon distribution in No.3 area is studied from radon plane distribution map.Then the radon anomaly is determined by fractal content-frequency method,thus predicting the range and position of underground gasification working face and providing evidence for better control of underground coal gasification and selection of process parameters.Ulanchap is a low-level radioactive area,activated carbon method for measuring radon has achieved good results in monitoring UCG in Ulanchap and provides a basis for the controlled combustion of underground coal.In view of this,this method can be used as monitoring method in the structural belt,goaf and exploration of geological hazards in low-level radioactive area,thus provides a new method of geophysical exploration for low-level radioactive area.