Mechanical pyrolysis in a shear retort

Abstract

Mechanical visbreaking and pyrolysis between counter-rotating coaxial centrifugal impellers in a continuous radial counterflow process minimizes wastewater discharges. In one example, a cataclastic shear retort comminutes, shear thins, and shear heats an axial feed, such as tar sand, oil shale, coal tailings, distillation bottoms, or lignite. Pyrolyzing the feedstock in this shear retort yields a product stream of gases, naphthas, and oils which first mixes with the feedstock and then is axially extracted, while spent solids are simultaneously extruded from the periphery as coked devolatilized residue, such as char sand for upgrading soil to terra preta. Recirculation of shear-heated solids in long residence time within the shear retort brings heat from the spent solids at the periphery to the feedstock without an external heated sand loop. CO2 emissions from combustion to heat water for oil extraction are eliminated.