Combustion Properties of Black Liquors from Alkaline Pulping of Wheat Straw and Reed Canary Grass, 2001 Pulping Conference Proceedings

J. Louhelainen, R. Alen, Z. Feng--Combustion of black liquor after evaporation in the recovery furnace to recover energy and cooking chemicals is becoming a more attractive technique also for nonwood pulping. However, due to the high viscosity of nonwood- based liquors, their heat treatment prior to combustion to reduce viscosity is necessary. In this study, the combustion properties of black liquors from soda-AQ pulping of wheat straw and soda-AQ and kraft pulping of reed canary grass were investigated as such and after heating at 190°C for 30 minutes in a laboratory furnace at 800°C by a single droplet technique. In addition to swelling, the duration of different burning stages, i.e., devolatilization and char burning, was determined for each liquor. Finally, to develop rapid methods for predicting the combustion behavior of black liquor, adequate correlations between the FTIR(Fourier transform infrared) spectral data (indicating chemical composition) and the combustion properties of the studied black liquors were explored.