Retorting of pulverized oil shale in fluidized-bed pilot plant

Abstract

This paper describes the research on fluidized-bed retorting of pulverized oil shale on pilot-plant scale (daily processing capacity of 50 tonnes oil shale). Chinese Yi Lan pulverized oil shale 0-3 mm was used as feed. Oil shale is fed and pyrolyzed in a fluidized-bed pyrolyzer, where it is heated to about 500°C by recycled hot shale ash coming from a fluidized-bed combustor. Nitrogen, coal gas or superheated steam is used as fluidizing agent in the pyrolyzer. The shale char formed from oil shale in the pyrolyzer mixed with shale ash is recirculated to the fluidized-bed combustor, where it is burnt by incoming air (as fluidizing agent) to form shale ash at about 700°C and is recycled to the pyrolyzer as hot solid heat carrier. The mixture of shale oil vapors and pyrolysis gas, formed from oil shale, mixed with steam or other fluidizing agent coming from the pyrolyzer, comes through two cyclones for removal of entrained dust and is washed by warm water to condense heavy shale oil, then goes to cooler for recovery of light shale oil. The total shale oil yield accounts for 80% of Fischer assay. The properties of shale oil and pyrolysis gas are analyzed. © 2009 Estonian Academy Publishers.