A packed tower is modelled transiently for fluid-solid reactions. Heat
and mass transfer are considered, with allowance for structural chang
es. The Knudsen, molecular and bulk flow terms are accounted for in th
e packed tower and within the pellets of the packing. Homogeneous, het
erogeneous and catalytic reactions are handled. Conduction, convection
and radiation model of heat transfer are considered. The thermophysic
al, structural and transport properties are included as variables. Thr
ee levels of space are used in the system: packed tower, macroporous p
ellets, and microporous zone (grain). The solution in these spaces inc
ludes the distributions of concentrations, temperature, pressure and s
olids conversion as well as all other parameters at any given time. Th
e three zones are linked together via boundary values.