Potassium Removal from Palm Empty Fruit bunch for slagging and Fouling Reduction

Abstract

Gigantic waste from palm oil mills known as palm empty fruit bunch (EFB) is useful biomass waste residue for combustion power generation. Barrier for utilizing it as the solid fuel lies in its high potassium (K) composition. In this study, hydrothermal treatment at 60 and 120 °C as well as ambient temperature treatment at 28-30 °C (considered as soaking set) for 30, 60, and 120 min under 50,75, and 100 g/L (EFB total solids to distilled water ratio) were applied aiming to remove K, and at the same time to reduce slagging index (SI) and fouling index (FI) in EFB boiler. Experimental results proved that increasing treatment temperature and detention time while lowering total solids concentration (TS) for hydrothermal and ambient temperature treatments promoted higher K removal and slagging and fouling reduction, respectively. Linear regression evidenced that there is the reduction in both indices when K removes through inverse correlation with sufficient coefficient R2 of 0.76, 0.98, and 0.87 for remaining K vs. SI and of 0.85, 0.97, and 0.84 for remaining K vs. FI from treatments under 50, 75, and 100 g/L TS, successively. In comparison with the K of 20,467 mg/kg in raw EFB (without any treatment), highest K removal with the value of 90.7±0.10% (1,910 ± 14.4 mg/kg remaining), 88.8±1.00% (2,301 +210 mg/kg remaining), and 87.9 ± 0.0 % (2,468 ± 173 mg/kg remaining) were obtained at highest temperature of 120 °C for longest detention time of 120 min under the three TS, respectively. In addition, the regression model expressed a good fit to the data and able to describe the relative interaction of the three independent variables on K removal with the significant difference of p<0.0001 and the high determination of coefficient R2 of 0.89. According to the mass balance, which is the research closure, showed that EFB was reduced in its TS amount from 419 to 305 kg/ton EFBwet (~ 27.2 % loss) at the end of process flows; promoting the removal and reduction of some adverse parameters like K, SI, and FI as the good findings for better EFB fuel quality and combustion power plant.