Experimental Investigation of Expansion during Formation Process of Formed Coke Blending with Torrefied Biomass

Abstract

The mechanisms of expansion and shrinkage behavior of the briquettes of coal or torrefied biomass were investigated by measuring the weight loss of coal and torrefied biomass and the expansion and shrinkage of the briquettes. In the case of torrefied biomass, particularly large expansion occurred at temperatures below 600°C. In the case of hot briquetting, the expansion was small below the briquetting temperature, suggesting that the expansion originated from relaxation of residual stresses during briquetting process. When coal and biomass were blended, the maximum strain was slightly close to the briquette of coal, and the temperature at which the maximum strain was taken was almost the same as that of the briquette of torrefied biomass, and in both cases, additivity was not valid. The expansion and shrinkage behavior of the briquettes was modeled as thermal expansion unique to the material, expansion due to relaxation of stresses accumulated during molding, and shrinkage due to the release of volatiles.