Effect of pyrolysis process on the properties of briquettes produced from different particle size peanut shells and grape pruning residues

Thermal processes like pyrolysis of biomass briquettes are frequently used to produce char with highly calorific value. The aim of this work was to obtain briquettes from various mixtures of peanut shells (PS) and grape pruning (GP) with different particle sizes, followed by pyrolysis of these briquettes to increase their heating value. The proximate analysis, physical and mechanical properties and energy analysis for biomass and char briquettes were measured. The PS and GP treatments were ground to an average particle size of 4, 8, and 12 mm, after which the particles of PS and GP were mixed with a starch binder (SB) in the weight ratios 50:40:10, 40:50:10 and 50:50:0, respectively. Drying, grinding, adding binder, densifying the residues and its pyrolysis were done to produce nine treatments of biomass and char briquettes. According to the results, statistical analysis validated that all properties of the biomass and char briquettes depend on the mixing percent and particle size of the raw material. The treatment (peanut shells (50 %), grape pruning (40 %) starch binder (10 %)) with particle sizes 4 mm achieved the best values of heating value 18.24, 21.14 MJ kg⁻¹ with an energy yield 81.12 %, density 914.9, 771.4 kgm⁻³, compressive strength 8.24, 1.57 × 10⁻³MPa and durability 99.86 and 95.89 % for biomass and char briquettes respectively. The net energy for produce 1 kg of biomass and char briquettes was 17.89 and 20.71 MJ respectively. The net yield for produce a ton of biomass and char briquettes were approximately 101.69 and 233.25 $ton⁻¹ respectively.