Design, Manufacturing and Operation of a Down draft Gasifier for Coconut Shell Charcoal Generation in Dankotuwa, Sri Lanka.

Abstract

This study presents the design, fabrication, and operation of a downdraft gasifier specifically developed for coconut shell charcoal production in Dankotuwa, Sri Lanka. Traditional pit methods of charcoal production result in low yields, uncontrolled emissions, and limited process control. The proposed gasifier overcomes these issues by enabling batch feeding of green coconut shells from the top, continuous operation, and controlled partial oxidation to extract charcoal without reducing it to ash. The system incorporates a combustion cone with four strategically oriented air nozzles to ensure uniform material flow and high-temperature combustion, followed by a rotating grate in the reduction zone to regulate charcoal expulsion. Commissioning trials with a 1000 kg feedstock demonstrated a certain charcoal yield of at least 28% (w/w) while generating producer gas of sufficient calorific value to replace approximately three cubic yards of wood logs per 10-hour shift for industrial heating. The dual outputs of charcoal and producer gas provide both economic and environmental benefits, making the system a viable solution for small- to medium-scale enterprises seeking sustainable, low-cost energy.This study presents the design, fabrication, and operation of a downdraft gasifier specifically developed for coconut shell charcoal production in Dankotuwa, Sri Lanka. Traditional pit methods of charcoal production result in low yields, uncontrolled emissions, and limited process control. The proposed gasifier overcomes these issues by enabling batch feeding of green coconut shells from the top, continuous operation, and controlled partial oxidation to extract charcoal without reducing it to ash. The system incorporates a combustion cone with four strategically oriented air nozzles to ensure uniform material flow and high-temperature combustion, followed by a rotating grate in the reduction zone to regulate charcoal expulsion. Commissioning trials with a 1000 kg feedstock demonstrated a certain charcoal yield of at least 28% (w/w) while generating producer gas of sufficient calorific value to replace approximately three cubic yards of wood logs per 10-hour shift for industrial heating. The dual outputs of charcoal and producer gas provide both economic and environmental benefits, making the system a viable solution for small- to medium-scale enterprises seeking sustainable, low-cost energy.