This report on JAYCOR' s computer code for mixing and agglomeration in fluidized-bed coal conversion reactors, called FLAG (Fluidized-bed Aglomerating Fasifiers) consilsts of two volumes. The first volume covers the description of each module (Its assumptions, problem formulations, and solution techniques) and the relation of these modules to one another in the context of the total integrated code. The second volume is a Users I Manual, intended to assist process engineers to make routine calculations. It is the objective of JAYCOR' s modeling effort to provide a practical engineering tool which, when validated, can be used as the basis for extensive parametric studies, component or reactor design, optimization, scale-up, hazard analyses. and for additional insights into the multitude of interacting physical and chemical processes. insights that will be valuable in devising alternate operational procedures and improving the performance and control of the reactor. To this end, the general approach adopted in developing the FLAG code was to use fundamental principles of physics whenever It was practical. so that the number of further suppositions could be minimized. It is true, however, that most real-world processes cannot be adequately or economically described by first principles. The formulations of these processes include appropriate empirical correlations which can be refined or replaced later when better theories or data become available. A schematic drawing of the IGT experimental cold-flow fluidized-bed(l-I) is shown in Figure l~l. This unit was modeled as an example of cold-flow and reactive-flow simmulations. The unit consisted of a semi-circular plexiglas column 30.5 C1lII in diameter having a semi-circular jet nozzle 2.54 em in diameter.