Combustion characteristics of densified solid biofuel with different aspect ratios

Bio-coke is a solid biofuel with a high density and high compressive strength. Demonstration tests have shown that bio-coke can be used as an alternative to coal and coal coke. The effects of biomass type and production conditions on combustion characteristics have been studied for small diameter bio-coke (phi 50 mm or less). In this study, we focused on fuel size and investigated the combustion characteristics of phi 12 to 100 mm samples. Experiments were conducted in a preheated, forced convection atmosphere using a batch-type vertical combustion apparatus to simulate rapid temperature increase and combustion under isothermal conditions in a gasification and melting furnace or blast furnace. Two biomass species (Japanese cedar and green tea) were selected as materials to study the effect of biomass species. We developed experimental correlations to predict the combustion time of bio-coke, considering the effects of scale and aspect ratio. The flaming and char combustion times of bio-coke can be approximated using the shape factor (V/S)(n) even when the aspect ratios are different. We obtained that the characteristic length is (V/S) to the power of 0.52-0.64. Furthermore, we found that Japanese cedar bio-coke has 2.5 times faster in flaming combustion than green tea bio-coke.

Automated summary

Bio-coke is a solid biofuel that can replace coal and coal coke. By studying the effects of biomass type and production conditions on combustion characteristics, it was found that the combustion time of bio-coke can be predicted using a shape factor and is not affected by aspect ratio. Additionally, Japanese cedar bio-coke has a 2.5 times faster flaming combustion rate compared to green tea bio-coke.