THE EFFECT OF ADDING CANDLENUT SHELL INTO THE LOW-RANK COAL ON COMBUSTION PERFORMANCE
Daud Patabang1,3*, Effendy Arif2, Jalaluddin2*, Nasruddin Aziz2
1Graduate Student in Mechanical Engineering, Hasanuddin University, Gowa, Indonesia
2Department of Mechanical Engineering, Hasanuddin University, Gowa, Indonesia
3Department of Mechanical Engineering, Tadulako University, Palu, Indonesia
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The potential of coal in Indonesia approximately 151 billion tons, there are 61% of Low-rank coal (LRC), which has a Higher Heating Value (HHV) of 5,100-6,100 kcal/kg and Moisture content of 30-40%. Combustion of the LRC contributes to global warming due to its CO2 emission. The LRC has also a low igl (CNS). The combustion performance of LRC mixed with CNS was investigated by determining its combustion efficiency and the impact on combustion gas emission including Carbon Dioxide (CO2), Carbon Monoxide (CO), Nitrogen Oxide (NOx), and Sulfur Dioxide (SOx). This study was conducted by adding CNS into LRC of 10%, 30%, 50%, 70%, and 90%, respectively. The characteristic of the specimen is obtained from proximate and ultimate analysis based on ASTM standard. The combustion performance of mixing LRC and CNS was investigated in the electric furnace combustors with the burn-out temperature of 500, 625, 750, and 875 oC respectively. The combustion oxidant used oxygen which was supplied constantly. The combustion gas emissions were measured by using Thermoline MRU Air Fair VARIO plus test apparatus. The result shows that the addition of CNS into the LRC improves combustion performance significantly. The results show that the addition of 10% of CNS into the LRC yield the combustion efficiency varies in the range of 0.92 – 14.42%. The addition of CNS into the LRC has a significant impact on reducing CO2, CO, NOx and SOx emissions. For example, adding 10% CNS into the LRC can reduce SOx emission of 16.80%, and adding 90% CNS of 80.67% with combustion temperature of 500 oC. Improving the combustion performance by increasing combustion efficiency and reducing gas emissions will reduce global warming and also decrease slagging and fouling of combustion apparatus due to decrease of Sulfur content in the CNS and LRC mixtures.