Further Development of a General-Purpose, Packed-Bed Model for Analysis of Underground Coal Gasification Processes

摘要

Further development of a theoretical modeling analysis for characterizing reacting flows through packed beds is presented. These flows are related to the underground coal gasification conditions in terms of combustion and multi-component chemical reactions taking place inside charring coal beds. Time-dependent, two-dimensional (including axisymmetrical) partial differential equations (PDE's) describing conservation of mass, species, momentum, and the thermal energy are formulated. These PDE's are then recast into a set of ordinary differential equations (ODE's) with time the independent variable. The resulting ODE's are solved by applying a method-of-lines (MOL) technique. The present formulation considers: the transport phenomena at the wall; various transient flow cases; reactions of gas and solid species; a wide range of options on the boundary conditions; temperature-dependent physical parameters; and rezoning capabilities. A numerical code called GSF has been developed, and computer runs have been performed to verify various aspects of the physical models as well as the numerical approach taken in the present analysis. These include favorable agreements with available analytical solutions for simple, one-dimensional flows and two-dimensional non-isotropic heat transfer to a wall. For more complicated flow situations for which there are no analytical solutions, good agreements between the results of the present method and those of alternative numerical methods have also been obtained. 27 refs., 13 figs. (ERA citation 10:050757)