Development of a Small-scale Portable Biochar Kiln for Biochar Production

Abstract

A small-scale portable biochar kiln was developed to produce biochar using crop residues. The biochar kiln consisted of an inner cylinder, outer cylinder, ash removal chamber, gate, grated plate, perforated pipe, cover, air intake pipe, lifting mechanism, frame, and rollers. Total weight of the developed kiln was 62.50 kg, and cost for fabrication was ` 10,000/-. The biochar kiln was tested on wheat husk, maize stalk, maize cob, and paddy husk. The input capacity of the kiln for wheat husk, maize stalk, maize cob, and paddy husk was 5 kg, 4 kg, 15 kg, and 7 kg, respectively. The conversion efficiency of the developed biochar kiln was 42.2% for wheat husk, 40.89% for maize cob, 34.09% for maize stalk, and 35.14% for paddy husk residues. Operating time required for carbonisation of selected crop residues ranged from 84 min to 104 min. The average operating temperature of the biochar kiln was 296 °C, 254 °C, 269 °C, and 256 °C for wheat husk, maize stalk, maize cob, and paddy husk, respectively. Biochar produced with wheat husk had available N (5.82 g.kg-1), available P (3.47 g.kg-1), available K (92.23 g.kg-1), pH (10.73), cation exchange capacity (78 cmol.kg-1), water holding capacity (71%), and bulk density (0.55 g.cm-3). The operational cost of biochar production was 77.86 ` .kg-1 for wheat husk, 100.28 ` .kg-1 for maize stalk, 53.52 ` .kg-1 for maize cob, and 77.40 ` .kg-1 for paddy husk. The low-cost portable biochar kiln operable near the field throughout the day would be convenient for small and marginal farmers for biochar production.