Design, Development, and Optimization of Sustainable Pyrolyzer for Biochar Production from Agricultural Crop Residue

Abstract

This article presents an energy-efficient biochar kiln that produces biochar from agricultural crop residues. The kiln is designed to be easy to operate and has minimal requirements for special operations. It works by heating biomass in a combustion chamber using recirculated pyrogas. The study optimized the process parameters and economics of producing biochar from wheat straw using Response Surface Methodology (RSM) based on Central Composite Design (CCD). The sustainable pyrolyzer had a thermal efficiency of 43.69%, with steady-state operation at 517.68 ± 98.18 °C. It produced an average of 54.57 ± 1.86 kg of biochar per batch, using 36.96 ± 3.66 kg of subabul (Leucaena leucocephala) as fuel and 179.61 ± 2.87 kg of wheat straw as feedstock. Subabul is chosen as a fuel due to its rapid growth, high calorific value, low moisture content, efficient combustion, and minimal smoke emission. The thermogravimetric index (TGI) and calorific value of WSB were 7.14 and 25.91 ± 0.74 MJ/kg, respectively. The benefit–cost ratio and payback period were 2.27 ± 0.16 and 4.92 ± 0.44 months, respectively.