A Study of the Effect of Additive Concentration in B40 Biodiesel on the Performance of the Air Preheater in a Steam-Powered Electric Power Plant

Abstract

The increased use of B40 biodiesel in coal-fired power plants in Indonesia poses challenges related to fuel characteristics, particulate matter content, heat transfer efficiency, and combustion emissions. The present study explores the impact of 2-ethylhexyl nitrate (2-EHN)-based additive concentrations on B40 characteristics, air preheater (APH) performance, and combustion emissions. The additive was subjected to testing at concentrations of 0, 200, 300, 400, 900, 1000, and 1100 ppm. The fuel characteristics evaluated included viscosity, particulate content, cetane number, and Fatty Acid Methyl Ester (FAME). Combustion testing was conducted for a period of eight hours under cold-start boiler conditions, with the exclusion of coal as a fuel source. Operational data were collected at 15-minute intervals via the Distributed Control System (DCS), while SO₂, NO_x, CO, and CO₂ were monitored hourly via the Continuous Emission Monitoring System (CEMS). The study’s findings suggest that the incorporation of the additive did not result in substantial alterations to the viscosity of B40 at ambient temperatures. However, it led to a significant reduction in the particulate content. At a concentration of 1000 ppm, the suspended particulate matter decreased from 52.0 mg/L to 1.7 mg/L, representing a 96.7% reduction. Concurrently, the number of particles wit sizes ≥4, ≥6, and ≥14 µm decreased by 77%, 87%, and 95%, respectively. A concentration of 1000 ppm was found to enhance the thermal performance of the air preheater. An enhancement in the efficiency of the primary air heater (PAH) was observed, with an increase from 75.84% to 78.86%. furthermore, a rise in efficiency was observed for the secondary air heater (SAH) a from 40.49% to 44.12%, and for SAH B, from 38.75% to 42.23%. the incorporation of additive at a concentration of up to 1100 ppm resulted in a 16.40% reduction in CO emissions and a 5.33% reduction in NOx emissions. Conversely, there were minimal changes observed in SO₂ emissions, while CO₂ emissions exhibited a slight increase. The findings of this study indicate that a concentration of approximately 1000 ppm was conducive to achieving optimal performance in terms of reducing particulate matter and enhancing the efficiency of the air preheater. However, it was observed the higher does did not invariably result in superior performance.