Research On Soil Radon Measurement Technology Of Acquiring Underground Coal Gasifier Temperature Field

Development of underground coal gasification(UCG)is a new research on world's coal mining and can fundamentally solve a series of technical and environmental problems in the traditional mining method.Using the advanced underground coal gasification technology to achieve clean and efficient utilization of coal can guarantee China's energy supply and coordinate to solve the coal utilization efficiency and the ecological environment problems.The combustion state of underground gasifier must be understood so that underground coal gasification can be in the control.It is a key problem to monitor the change and trend of underground gasifier.It can ensure the quality of produced gas in the gasification process and maintain underground gasifier temperature to avoid overburden stratum's felling in burning zone and to avoid the ground subsidence.So,using a kind of effective and feasible measurement technology for acquiring underground gasifier temperature field has a vital role in stable control of underground coal gasification.This paper is based on the national natural science fund project: “Research on Soil Radon Method of Acquiring Gasifier Temperature Field in Coal Gasification”(41204133).Real-time measurement system of ? energy spectrum based on multiple parameters soil radon electrostatic accumulation method is developed after the research on method and system of underground coal gasification temperature acquisition and the model establishing of soil radon anomaly above the underground gasifier combustion zone.The soil radon method of acquiring underground gasifier temperature field is designed,and it has been applied in the field in Wulanchabu of Inner Mongolia according to the working process.Thesis finally has main research results as follows:1,The model is established that the soil radon anomaly above the underground gasifier combustion zone in the way that combines radon release simulation test and radon migration model derivation.The model discusses the forward modeling process of surface soil radon anomaly caused by underground coal gasification.The feasibility of soil radon measurement of acquiring underground gasifier temperature field is explained,and it is validated by the underground coal gasification combustion zone surface radon measurement test.The related law of the underground gasifier temperature and surface soil radon anomaly is discovered that provides a theoretical basis and practical basis for soil radon measurement technology of acquiring underground gasifier temperature field.2,For the first time,it is proposed that using the multiple parameters array type multipoint synchronous soil radon electrostatic accumulated ? energy spectrum real-time measurement based on Internet of things to study the combustion state of underground gasifier.According to the requirements such as real-time,continuous,high sensitivity characteristics of the soil radon measurement in the process of underground coal gasification,the multiple parameters soil radon electrostatic accumulated ? energy spectrum real-time measurement system is developed that is based on the Internet of things,has strong real-time anomaly identify ability,good stability and high sensitivity.The system has the characteristics as follows: 1)Array type multipoint synchronous measurement is beneficial to the comparability of different point measurement data;2)Soil radon electrostatic accumulation method,which is beneficial to increase the measurement information,reduce the effects of radioactive statistical fluctuation.And it can monitor soil radon changes in real time to facilitate real-time monitoring of the combustion process of underground gasifier;3)Using ? energy spectrum measurement can improve the ability of identifying anomaly in real time.It is easier to identify radon anomaly information with a delay than underground coal temperature changes.At the same time,the information of radon and its progeny also can be got to identify whether anomaly is rooted in the deep underground;4)Multiple parameters real-time measurement can correct various factors on the impact of soil radon measurement and improve the quality of the later analysis data;5)The multiple sensor information is integrated through the Internet of things technology so that gasifier state parameter is in the real-time management;6)The automatic correction method of the temperature and humidity based on the electrostatic accumulation method is proposed.The real-time soil radon measurement value can be automatically corrected using the real-time temperature and humidity measurement value in the corresponding soil.3,A soil radon method of acquiring underground gasifier temperature field is designed.The method's process includes acquiring surface soil radon anomaly distribution,the relative change rate of soil radon time series filtering,the time calibration of the measuring radon data,establishing the mathematical model of the relationship between surface soil radon and underground gasifier temperature,and the reverse illation of underground gasifier temperature field,etc.This method has some innovation points as follows: 1)On the basis of simulation test,for the first time,the extraction method of the relative change rate of soil radon based on the trend surface analysis is proposed in view of the particularity of the underground coal gasification.2)The method of wavelet filter is applied to filtering on the time series of the relative change rate of soil radon for the first time learning from its application in gamma energy spectrum processing situation.3)The time calibration of the soil radon measurement is proposed for the first time for the underground coal gasification.The soil radon data can be really measured in real time.The time calibration creates the conditions for determining the real-time change rule of the soil radon anomaly in the process of the underground coal gasification,and for acquiring underground gasifier temperature field in different time.4)The mathematical model of the relationship between surface soil radon and underground gasifier temperature is establishde by neural network method with the combination of principal component analysis(PCA).The reverse illation of underground gasifier temperature field is implemented by the model.In the feature information extraction of the measurement data,it enhances the extraction ability of weak anomaly information using principal component analysis to extract the characteristic value to construct feature vectors and constitute a multiple parameter array type soil radon measurement values of characteristic information matrix.In conclusion,this paper completes a research on soil radon measurement technology of acquiring underground coal gasifier temperature field.A real-time measurement system of ? energy spectrum based on multiple parameters soil radon electrostatic accumulation method is designed and implemented.A soil radon method of acquiring underground gasifier temperature field is designed.The real-time,stable,sensitive and multi-point synchronous monitoring of underground gasifier temperature field is implemented to provide the scientific basis and technical support for the stability control of underground coal gasification process.