Thermal degradation of alkaline black liquor from wheat straw.: 2.: Fixed-bed reactor studies

The usual problems experienced with common recovery boilers are aggravated in processes involving alkaline black liquor derived from straw. The consequent need to develop alternative processes for the use of black liquor for energy purposes, such as pyrolysis or gasification, requires a good understanding of the thermochemical. behavior of this substance. There is, however, little information available. Part 1 of this work (Gea, G.; Murillo, M. B.; Arauzo, J. Ind. Eng. Chem. Res. 2002, 41, 4714), therefore, studied the thermal degradation of alkaline black liquor from straw in a thermogravimetric system. The present work also focuses on its pyrolysis. In particular, the influence has been analyzed of the final pyrolysis temperature (250-900 degreesC) and the heating rate (5-30 degreesC/min) on the product yields, gas composition, and specific surface area of the resulting char in a fixed-bed reactor. The results obtained show that both the energy recovery and the specific surface area of the char increase with a rise in the final pyrolysis temperature and the heating rate.