A commercial-size, hot-solids recycle retorting process, consisting of a staged fluidized-bed pyrolyzer and a lift-pipe combustor, was simulated using a previously developed mathematical model. The focus of this work at Lawrence Livermore National Laboratory (LLNL) is to show the effects of varying key process parameters. A design study shows the effects of varying process specifications on cost-related items such as reactor sizes, utility requirements, and yield. An operation study, in which the reactor dimensions were fixed, shows how the plant's sensitivity to some unavoidable changes and to the effectiveness of several strategies for controlling process conditions. We present tabulated and graphical results from the 22 individual parameter studies.