Perpustakaan Digital ITB

This analysis focuses on the power plant performance during high ratio cofiring trial at PLTU Jawa Barat 2 Pelabuhan Ratu. The trial was conducted with three different fuel blends: 0%, 10%, and 20% sawdust. A sawdust type biomass is used for fuel blend with coal. This research aims to evaluate cofiring process with key performance indicators including Net Plant Heat Rate (NPHR), Specific Fuel Consumption (SFC), Specific Steam Consumption (SSC), and greenhouse gas emissions. There is a significant trade-off between the environmental benefits and the overall power plant efficiency. Greenhouse gas emissions, which includes CO2, SOx, and NOx, decreases as cofiring ratio increases. For CO2 emission, the total emission is 116.74% for 0% cofiring, 101.5 t/h for 10% cofiring, and 90.75 t/h for 20% cofiring. For SOx emission, the total emission is 1.85 t/h for 0% cofiring, 1.67 t/h for 10% cofiring, and 1.64 t/h for 20% cofiring. For NOx emission, the total emission is 9.22E-03 t/h for 0% cofiring, 6.54E-03 t/h for 10% cofiring, and 4.15E-03 t/h for 20% cofiring. This occurs due to the reduction of carbon, sulphur, and nitrogen content in higher sawdust ratio fuel blend. Due to high moisture in higher sawdust fuel blend, combustion temperature also decreases leading to less NOx emission. The positive environmental improvement was accompanied by a reduction in plant efficiency. This is shown from the power plant performance parameters. There is a significant increase in Net Plant Heat Rate (NPHR) for higher cofiring ratio. The value rise from an average of 12113.67 kJ/kWh at 0% cofiring, 13050.24 kJ/kWh at 10% cofiring, to 15369.95 kJ/kWh at 20% cofiring. This increase is primarily due to the higher moisture content of sawdust, which demands additional energy for combustion and a rise in the plant's auxiliary power consumption. The average SFC also increased with higher sawdust ratios starting from 0.61 t/MWh at 0% cofiring, 0.68 t/MWh at 10% cofiring, and 0.77 t/MWh at 20% cofiring. This means fuel with higher sawdust ratio has lower calorific value. Similarly, SSC increases at higher cofiring percentages starting from 11.02 t/MWh at 0% cofiring, 10.99 t/MWh at 10% cofiring, and 11.15 t/MWh at 20% cofiring. This indicates boiler inefficiencies at lower operating loads with the non-ideal fuel mix. The study concludes that while sawdust cofiring effectively reduces emissions, it also introduces operational challenges and reduces overall plant performance.