Simulation Research On Temperature Changing Regularity Of Coal Core During Freezing Process

In the process of coal seam drilling core,gas desorption fast and loss amount,which leads to the distortion of the measured value of gas content in coal seam.Based on reducing the environmental temperature can inhibit gas desorption,and the lower the temperature,the more obvious the inhibitory effect,then we propose the method of freezing core.This paper choice the experimental test and theoretical analysis,and refrigeration dose is calculated by different freezing methods first.Then refrigeration effect of different freezing methods was investigated.Last we choice the best way of cooling method,that is: dry ice contact freezing and dry ice-ethanol contact freezing.Based on simulation test device of freezing core,collecting coal sample that come from 42207 coal bed in liulin xingwu mine.by using self-made mold and pressure loading mechanism,we make briquette.Taking the briquette as research object,we test temperature cooling law and pressure variation law under different pressures.The results show that::(1)Through the research of physical properties of dry ice,the experimental equipment and cooling condition,calculating the dry ice freezing test.(2)For a variety of freezing ways,dry ice contact freezing and dry ice-ethanol contact freezing is the best freezing ways.(3)The greater the initial equilibrium pressure,the shorter the time for reducing coal core temperature to the low temperature,the longer maintain time at low temperature and the lower the temperature of coal core.Under the initial equilibrium pressure of 2.15 MPa,the coal core is reduced to 0? for 14 min with dry ice contact freezing method,and just 10 min with dry ice-ethanol contact freezing method.(4)During the freezing process of coal core,pressure declining of coal tank when the temperature decreasing,pressure ascending of coal tank when the temperature rising.In the stable stage of cooling,the linear relationship between the pressure decline and the temperature decrease.(5)According to the experimental results,both the two methods can achieve the purpose of freezing,and the effect of dry ice-ethanol contact freezing way is better thanthe dry ice freezing way.