Performance of flameless combustion using palm oil mill effluent biogas

Abstract

Biogas produced from palm oil mill effluent (POME) is a type of renewable energy source that is available in abundance in Malaysia from its large palm oil industry. However, due to its low calorific value, POME biogas full potential has not been fully explored. Flameless combustion is new low NOx combustion method which is believed to be able to accept low calorific fuels easily. In this study, POME biogas has been used to fuel a flameless combustor and its performance was analyzed in comparison to flameless combustion of natural gas. A biogas compression and storage system was designed and tested to fuel the flameless combustion system. Results show that mild flameless combustion regime is achieved for natural gas, simulated biogas (75% natural gas, 25% CO2) and POME biogas. POME biogas flameless combustion has slightly lower average furnace temperature (2.69% reduction) due to increased inert gas in the furnace chamber. Flameless combustion produce a larger and more uniform combustion area (Rtu = 0.097) compared to conventional flame combustion (Rtu = 0.21). NOx emission measurement has shown reduced NOx emission in flameless combustion of natural gas, POME biogas and simulated biogas. The magnitude of NOx emission in flameless combustion is 6 ppm in average for the three fuel type. Equivalence ratio of combustion mix has little effect of NOx formation.