Improving Thermochemical and Physical Properties of Cocoa Pod Shell by Torrefaction and its Potential Utilization

Torrefaction process is one of the solutions to produce solid fuel from a cocoa pod shell (CPS). Fuel characteristics of CPS changed after torrefaction. Effects of torrefaction temperature and holding time on physical, thermal, and chemical properties of CPS were investigated in this study. The experiments were conducted in a tubular torrefaction reactor. Three different torrefaction temperatures of 200, 250, and 300°C and four holding times of 0, 30, 60, and 90 min were considered in this investigation. It was found that the color of CPS changed from light brown to black due to the increasing content of fixed carbon and depend on the torrefaction temperature and the holding time. The decrease in the grayscale value of the torrefied CPS represented an increase in HHV. Fixed carbon content and - higher heating value (HHV) of the torrefied CPS increased up to 17.5% and 41.3% compared to the raw CPS, while the volatile matter decreased up to 19.4%. The O/C and H/C atomic ratio decreased from 0.79 and 1.68 to 0.37 and 1.01, respectively, which corresponded to the increase of carbon content and decrease of oxygen and hydrogen contents. The properties of severe torrefaction CPS resembled between lignite and peat. The grindability and hydrophobicity of CPS was improved. The CPS based biochar should be used as a substitute for solid fuel that has the same characteristic to reduce the unfavorable effects of its potassium content.