Bubbling fluidized bed combustion of Syncrude coke

Abstract

Trials on the burning of Syncrude coke (solid residue of Athabasca oil sands after processing at the Syncrude plant, Fort McMurray, Alberta), were performed in an atmospheric fluidized bed combustion (AFBC) pilot plant (bed area 0.155 m2 ). The coke is high in sulphur, up to 7% by mass, and reduction of SO2 emissions is therefore necessary. An Athabasca limestone was used as the SO2 sorbent. The conditions of the trials were mean coke particle diam. 0.26 mm; mean limestone particle diam. 0.34 - 0.94 mm; fluidizing velocity 0.8 - 1.3 m/s; excess air, up to 7%; recycle ratio (fraction of cyclone catch recycled) 0 - 0.83; Ca/S mole ratio 1.7 - 2.9; bed temperature 966 - 1105 ° C. The high bed temperatures were needed to achieve stable burning and reasonable combustion efficiency. The combustion efficiency as measured by carbon burnup was 77 - 97%. At these temperature levels, sulphur capture was influenced most strongly by bed temperature. The capture was unexpectedly good up to 1050 ° C then fell sharply, practically to zero above 1100 ° C. It is concluded that Syncrude coke can be burned by AFBC with acceptable combustion efficiency and sulphur capture at bed temperatures of 950-1050 ° C and fluidizing velocities up to 1.3 m/s. Syncrude coke is high in vanadium, 0.18% by mass, as well as in sulphur. The results indicate that the vanadium is fixed in the ash and is not selectively concentrated in any of the product streams.