土壤生物炭的生产：三种窑模型的比较研究

Biochar has potentials for soil fertility improvement, climate change mitigation and environmental reclamation, and charred biomass can be deliberately incorporated into soil for long-term carbon stabilization and soil amendment. Many different methods have been used for biochar production ranging from laboratory to industrial scales. However, in countryside of developing countries,biomass is generally used for cooking but not charred. Biochar production techniques at farmer scale have remained poorly developed.We developed and tested biochar production kilns for farmers with a dimension of 50.8 cm × 38.1 cm(height × diameter), using three different setups for optimizing oxygen(O2) limitation and syngas circulation: airtight with no syngas circulation(Model I),semi-airtight with external syngas circulation(Model II) and semi-airtight with internal syngas circulation(Model III). A comparative assessment of these biochar production kiln models was made considering biochar pyrolysis time, fuel to biomass ratio, biochar to feedstock ratio and thermogravimetric index(TGI). Among the models, the best quality biochar(TGI = 0.15) was obtained from Model I kiln taking the longest time for pyrolysis(12.5 h) and the highest amount of fuel wood(1.22 kg kg-1biomass). Model III kiln produced comparatively good quality biochar(TGI = 0.11), but with less fuel wood requirement(0.33 kg kg-1biomass) and shorter pyrolysis time(8.5 h). We also tested Model III kiln in a three times larger size under two situations(steel kiln and pit kiln). The biochar to feedstock ratio(0.38) and quality(TGI = 0.14) increased slightly for the larger kilns. Quality of biochar was found to be mainly related to pyrolysis time. The costs for the biochar stove and pit kiln were US$ 65–77, while it was US$ 154 for the large size steel kiln. Model III kiln can potentially be used for both cooking and biochar production at farmer scale.

Production of biochar for soil application: A comparative study of three kiln models

Biochar has potentials for soil fertility improvement,climate change mitigation and environmental reclamation, andcharred biomass can be deliberately incorporated into soilfor long-term carbon stabilization and soil amendment.~Manydifferent methods have been used for biochar productionranging from laboratory to industrial scales.~However, in countrysideof developing countries, biomass isgenerally used for cooking but not charred.~Biocharproduction techniques at farmer scale have remained poorlydeveloped. We developed and tested biochar productionkilns for farmers with a dimension of 50.8 cm $times$ 38.1cm (height $times$ diameter), using three different setupsfor optimizing oxygen (O$_{2}$) limitation and syngascirculation: airtight with no syngas circulation (Model I),semi-airtight with external syngas circulation (Model II)and semi-airtight with internal syngas circulation (ModelIII).~A comparative assessment of these biochar productionkiln models was made considering biochar pyrolysis time,fuel to biomass ratio, biochar to feedstock ratio andthermogravimetric index (TGI).~Among the models, the bestquality biochar (TGI = 0.15) was obtained from Model I kilntaking the longest time for pyrolysis (12.5 h) and thehighest amount of fuel wood (1.22 kg kg$^{-1}$ biomass).~%Model III kiln produced comparatively good qualitybiochar (TGI = 0.11), but with less fuel woodrequirement (0.33 kg kg$^{-1}$ biomass) and shorterpyrolysis time (8.5 h).~We also tested Model III kiln in athree times larger size under two situations (steel kilnand pit kiln).~The biochar to feedstock ratio (0.38) andquality (TGI = 0.14) increased slightly for the largerkilns.~Quality of biochar was found to be mainly related topyrolysis time. The costs for the biochar stove and pitkiln were US$ 65--77, while it was US$ 154 for the largesize steel kiln. Model III kiln can potentially be used forboth cooking and biochar production at farmer scale.