Test of a modified small-scale biochar kiln

Abstract

The conventional kilns were used for biochar production, but it took more than 7-9 hours for processing, and its process temperature was not uniform because some of the material could be converted into biochar and used lots of heat source input resulting in low production efficiency. Then the objective of this research was to improve the biochar production by using modified biochar kiln by reducing the temperature distribution. A 50-liter kiln with a modified core was needed in this research. This core was heating source for the pyrolysis process. The heat source came from the combustion of biomass. The core pipe was core puncture diameter for releasing product gas between a process, and it was core puncture diameter in 3 sizes (i.e., 3.18 mm, 4.76 mm and 6.35 mm). Seven kilograms of corncob rice husk and longan peel were loaded in the biochar kiln using three kilograms of fuel. The physical and chemical properties of biochar were analyzed such as water content, pH, electrical conductivity (EC) using scanning electron microscope (SEM), and Energy-dispersive X-ray spectroscopy (EDX). The element and mineral compositions were also analyzed, including C, N, O, K, and P. It was found that most of the materials were converted into biochar at uniform temperature with the modified core. The temperature inside a kiln with the heat insulation the modified core was around 400-600°C better than the common core (100-700°C) and it took only 3 hours for the process. In terms of products obtained from pyrolysis condition, the average temperature positions inside the kiln were found to be 430 ± 583 °C, 271 ± 512 °C, and 189 ± 503 °C and consisted of biochar yield were found to be 45.7, 34. 3 and 31.4 wt.% for rice husk, corncob, and longan peel, respectively. Gas yields were found to be 68.6, 68.6, and 48.6 wt.% for longan peel, corncob, and rice husk, respectively Ash yields were found to be 10.0, 5.7, and 5.7 wt.%, for longan peel, corncob, and rice husk, respectively. The biochar properties from corncob rice husk and longan peel were beneficial, resulting in being useful for the soil amendment. It had suitable properties for improving the deteriorated soil structure conditions.