Pyrolysis and Gasification of Orinoco Tar and Orimulsion

Abstract

The deposits of Orinoco tar in Venezuela are estimated to amount to 80 percent of the deposits of crude oil in the Middle East. To examine the possibility for utilizing the Orinoco tar as chemical feedstocks, pyrolysis behavior of Orinoco tar and Orinoco tar-water emulsion (Orimulsion) was examined using a Curie point pyro-lyzer (CPP) and an entrained bed reactor. The gasification reactivity of the coke formed during the pyrolysis was also measured. Heavy tar was produced in about 80% yield from the Orinoco tar through the primary pyrolysis reaction regardless of temperature and pressure. The heavy tar, however, could be converted to valuable chemicals such as hydrocarbon gases, and BTX (benzene, toluene, xylene) in high yield through secondary gas phase reaction. At 800°C the sum of the yields of methane, ethylene, BTX and naphthalene reached more than 50%. Two kinds of coke were found to be formed: one was produced through the primary reaction, and the other was produced through the secondary gas phase reaction from aromatic compounds such as naphthalene. The yield of the former one was little dependent on pyrolysis conditions, whereas the yield of the latter one increased with the increase in the temperature and/or the residence time. At 1200°C the total coke yield more than 60%. The gasification rate of the coke was only one-seventh of that of a coal char in a steam atmosphere even at 1000°C.