Study on Spray Cooling of Ultra-high Temperature Production Wellbore in Underground Coal Gasification

In order to analyze the influencing factors of the cooling effect of water injection in underground coal gasification production wells, the finite element analysis method was used to simulate the temperature field of the produced gas under different mass flow, spray cone angle, atomized particle diameter and spray cycle. The results show that after the produced gas is cooled by spray, the gas temperature gradually increases along the axial direction at the outlet and decreases along the depth at the wall. On the premise of the same other conditions, increasing the mass flow of spray liquid can significantly reduce the temperature of high-temperature gas and increase the cooling rate; When the atomization effect is improved and the diameter of atomized particles is reduced, the cooling effect will be significantly improved; In a certain period of time, when the total amount of spraying is certain, the periodic spraying can significantly improve the cooling effect, but when the cycle time increases, the temperature at the wall will rise to a certain extent. Smaller spray cone angle has less influence on the cooling effect. When the spray cone angle increases to more than 40°, the casing wall temperature will decrease to a certain extent with the increase of spray cone angle; The research results provide a technical basis for the selection of spray parameters of underground coal gasification.