Solid Conversion

Throughout their conversion, solid fuel particles undergo many complex physical and chemical processes, and modeling these phenomena with sufficient accuracy is a key component to simulating the reacting flow inside entrained flow gasifiers. Broadly speaking, it is possible to divide the solid particle conversion into two phases: devolatilization and char consumption. Additionally, while the volatile gases and tar escape the particle, the char structure is formed, and it may look nothing like that of the original feedstock particle. Thus there are three essential processes that will be modeled: devolatilization, char structure formation, and char consumption. Current work is focused on char consumption modeling, which is done within the framework of a reaction-diffusion type equation for each char particle that is tracked. Sub-models for diffusion within the porous particle, heterogeneous and homogeneous reaction kinetics, surface area evolution and several other key processes are included. This approach allows for spatial and temporal variations within the particles and therefore yields improved accuracy and the ability to predict certain processes that aren't possible using an integral (effectiveness factor) approach.