The effect of steam explosion pretreatment on the physical and mechanical properties of the pellets made from empty fruit bunch (EFB) and palm kernel shell (PKS) was investigated and compared to that of softwood Douglas fir (DF). It was found that the high heating value of the empty fruit bunch was increased by 21% after steam explosion

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Oil palm residues are not currently suitable as feedstock for thermal energy generation because their high ash content can cause slagging, corrosion, and fouling. A water leaching treatment is a potential strategy to reduce the ash content in these residues. This study evaluates the effects of the duration and temperature of water leaching on two types of oil palm residues, namely, empty fruit bunches (EFBs) and palm kernel shells (PKSs). The optimum process duration for ash removal from EFBs was found to be 5 min, as the effect of convection on scrubbing was observed to remove substantial ash from the substrate during this period. A cross-flow model with estimated kinetic parameters of water leaching for EFB and PKS was developed and showed that three leaching stages of EFB achieved the greatest ash reduction from 5.47% to 2.63%. A low ash content of PKS showed no value for ash removal in any leaching process. Although there was no significance in the total ash reduction due to temperature effects, the leaching treatment was found to be most effective in reducing potassium, from 2.42% to 0.69% and 0.36% at 25 and 55 °C, respectively.

Previous measurements have shown that freshly made wood pellets continued to emit flammable gases such as CO, H2 and CH4 during storage and handling. The research reported in this paper examines whether the concentration of these emitted gases and the available oxygen within enclosed wood pellet spaces can reach flammable levels. Glass jars filled to 75% volume with pellets were sealed and placed in controlled environments at 25, 40 and 60°C for a period of 9 weeks. Each batch of the stored pellet had a moisture content of 4%, 9%, 15%, 35% or 50% (wet mass basis). The concentrations of carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), oxygen (O2), nitrogen (N2) and hydrogen (H2) were determined using gas chromatography. The flammability of the gas mixtures in the container headspace was calculated using ISO 10156 Standard ‘Gases and gas mixtures—Determination of fire and oxidizing ability for selection of cylinder valve outlets.’ It was concluded that the composition of the gas mixture does not reach flammable concentrations under all experimental conditions.