Modelling of flow at Thulin underground coal gasification experiments

Abstract

During the underground coal gasification experiments at Thulin, a series of tracer tests using 133xenon or helium as injected material were effected. These tests illustrated the hydrodynamics of the flow profile inside the underground reactor during the main operating periods: the series of reverse combustion tests and the gasification phase. The models developed to simulate the flow conditions are based on the material exchange between flowing fluid and the dead zone. The dead zone is represented either by a stagnant zone exchanging material with the flowing fluid in accordance with film theory or by a homogeneous porous zone exchanging material with the flowing fluid by pure molecular diffusion. With these models, excellent fits were obtained and physical significance of the parameters is possible in correlation with the gasifier operating conditions. The results show a little evolution of the flow conditions inside the underground reactor during the series of reverse combustion tests. On the other hand, during the gasification phase, the reactor volume calculated from the tracer results is proportional to the cumulative quantity of coal consumed.