Energy efficiency and emission assessment of a continuous rice husk stove for rice parboiling

The study presents a performance evaluation of an integrated rice parboiling stove (IRPS) fuelled with either rice husk or wood in comparison with the three stone fire (TSF) stove currently being used. The stoves were initially tested using the water boiling test. The efficiency, fire power and specific fuel consumption of IRPS were found to be 29%, 16 kW and 0.14 kg/kg rice husk, respectively. To enhance continuous steam production, a heat exchanger extension was made to the IRPS and the efficiency re-evaluated using the indirect boiler efficiency estimation approach, together with pollutants emission factors and safety. The stove efficiency after the extension increased to 46%. The emission factors for CO, CO2 and CxHy were in ranges from 10.6 to 12.0, 785-793, 0.4-2.2 g/kg of rice husk, respectively. Comparison between rice husk and wood combustion in IRPS shows that emission factors for rice husk were significantly lower than wood but decrease with stove fire power.