Karakterisasi Dinamis Pembakaran Biomassa Kulit Kopi dengan Starter Premix Udara–LPG pada Moving Fluidized Bed Gasifier

Abstract

The use of biomass as a renewable energy source through gasification is growing, but the success of the gasification process is greatly influenced by the stability of the combustion phase (starter). In a moving fluidized bed gasifier system, the dynamics of the temperature rise during the initial stage determine the success of the transition to the gasification process. This study aims to characterize the combustion dynamics of coffee husk biomass using an air–LPG premix starter with varying Air-Fuel Ratios (AFR). AFR variations of 17,55:1, 38,30:1, 63,83:1, and 76,60:1 were used to analyze their effects on ignition time, bed temperature, syngas composition as parameters of the starter-off condition, and biomass burning rate. Temperature parameters were observed in several chamber zones, ranging from the premix starter phase, feed starter phase, homogenizing phase, to the syngas production phase. Syngas concentration measurements were performed using MQ-4, MQ-7, and MQ-8 sensors, while the burning rate was calculated based on the biomass combustion rate during the initial ignition process. The results showed that an AFR of 17,55:1 produced the fastest ignition time of 530 seconds, whereas increasing the AFR resulted in a wider bed temperature distribution. Under starter-off conditions, the H₂ concentration increased from 1,23% to 2,03%, the CO concentration increased from 0,78% to 1,14%, while the CH₄ concentration decreased from 21,39% to 16,97%, although CH₄ remained the dominant component of the syngas because the process temperature was in the range of 300–400°C. In addition, the average burning rate increased from 235,53 g/min to 264,23 g/min as the AFR increased. Thus, variations in the air–LPG premix AFR have been shown to influence the dynamic combustion characteristics of coffee husk biomass, and can therefore serve as a reference in the development of starter systems for moving fluidized bed gasifiers