Conversion of hydrocarbon gases to liquid in the fluidized bed retort

A free radical steady-state mechanism has been developed to explain qualitative and quantitative aspects of the generation of hydrocarbon gases in the solid-recycle fluidized bed retort. The mechanism relies on what is known about butane cracking. The 1- and 2-butyl free radicals have been studied as representative intermediates responsible for the light gases: methane, ethane, ethylene, and propylene. The ratio of these gases formed from oil shale retorting exactly matches the ratio obtained from pyrolysis of n-butane and supports a butane-like cracking mechanism. In a variety of fluidized bed retorting experiments conducted with Lawrence Livermore National Laboratory's (LLNL) two-ton-per-day retort, free radical precursors of the hydrocarbon gases come to a steady state that efficiently equilibrates intermediates. Steady state is established rapidly without need for a gas recycle. Analogous reactions are possible for the entire homologous series of free radicals; as a result, the retort operator has considerable flexibility in choosing the nature of hydrocarbon products. A steady-state mechanism, in which alkenes convert precursors of gaseous hydrocarbons to liquid product, offers insight that can be used to obtain higher oil yields.