Model Test of Steam Migration during In-situ Thermal Desorption Remediation

The heat and moisture transport characteristics of steam in soil is a key factor affecting the remediation efficiency of organic contaminated sites using steam injection technology.This study carried out a series of model experiments using glass beads to simulate porous media,to investigate the tempo-spatial distribution of temperature during the injection of three types of steam:saturated steam,superheated steam and mixed steam.The experimental results reveal that the porous media can be divided into three zones according to the characteristics of temperature distribution:a high temperature zone,a temperature transition zone,and an ambient temperature zone.During superheated steam injection,a superheated steam zone emerges within the high temperature zone,where temperature exceeds 373K.The steam injection rate primarily affects the area of the high temperature and temperature transition zones.The addition of propylene glycol as a solubilizer to superheated steam significantly increases the area of the superheated steam zone and the maximum temperature within the porous media,although it results in a slower heating rate.Comparative analysis of steam properties impact on the steam migration process indicates that both the steam injection temperature and injection rate significantly influence the maximum temperature and the area of the high temperature zone.The inclusion of propylene glycol demonstrates dual effects.It significantly increases the maximum temperature and the thermal desorption remediation efficiency in the superheated steam zone.However,it inhibits the development of the high temperature zone.These findings provide a theoretical foundation for optimizing the design of steam injection engineering.