Abstract

Biomass is an important future fuel, see for example [1-5], and in turn further studies are needed to investigate such fuel [6-9]. During combustion/burning, biomass powder clustering inside the boiler/furnace is an important issue, as the complete combustion of biomass fuel and its residual emissions depend heavily on the particle cloud and distribution [10-14]. Figure 1 shows photograph of biomass powder clustering before introduced into boilers/furnaces. The aim of this study is to demonstrate the effect(s) of particle spatial distribution on biomass burning within boilers. Particle spatial distribution depends on a number of variables, such as particle size and shape. In particular, the biomass powder is prepared using logwood milling process and, as a result, the fuel powder is produced in irregular shapes and in various sizes [15-20]. When the particles exist in a variety of sizes and shapes due to the milling process, the clustering of the particles becomes unbalanced within the furnace/boiler area, and that will effect on the particle combustion scenario, as discussed afterwards. Biomass powder clustering of small particles (micro or nanoscale) is more likely to follow the gas than larger particles; and therefore, it is more likely that smaller fuel particles will have a sufficient time in an oxygen-rich environment to ignite and achieve high flame temperature. As the suspension loses energy, the dissipation rate decreases significantly, and the particle cluster decreases [21]. Additionally, the energy in the suspension fuel decays over time as a result of viscous dissipation at the gas phase. One of the clustering effects, self-propelled particles may accumulate in a region of space where they travel at a reduced velocity [22]. Upon aggregation, the particles move more slowly in areas of high particle density due to steric obstruction. Such behavior can lead to the so-called motility induced phase separation [23]. Nevertheless, this step of separation can be prevented by chemically mediated inter-particle forces or hydrodynamic interactions. Such interaction could explain the creation of finite clusters in furnaces [24,25].