Numerical Investigation of the Effect of Excess Air and Thermal Power Variation in a Liquid Fuelled Boiler

Abstract

In this study, flame structures, boiler efficiency and exhaust gas temperatures were investigated numerically at different thermal power and excess air ratio in a liquid fuelled boiler. Calculations were carried out at two dimensional axisymmetric conditions and Fluent was used as the computational fluid dynamics software. In all studies, the standard k-ε model was used for modelling the turbulent flow, the species transport model was used for modelling the combustion, and the pressurized swirl atomizer was used for modelling the injection. The calculations showed, that the droplet diameters after injection were reduced and droplets evaporated in a shorter period with increasing excess air. Exhaust gas temperatures were raised with the increasing boiler thermal power and excess air ratio. As expected, the higher flue gas temperature and excess air ratio showed lower boiler efficiency.

Simulasi Pengaruh Excess Air terhadap Kinerja PLTU Kapasitas 12,5 MW pada Beban Bervariasi

“…Surresh, et al [13] menganalisa performa PLTU existing dengan parameter excess air, temperatur inlet turbin dan temperatur air pendingin pada kondensor dan diperoleh hasil bahwa parameter input kondensor paling mempengaruhi perubahan efisiensi energi pada sistem. Penelitian mengenai temperatur exhaust gas dilakukan oleh Sungur, et al [14]. Peneliti ini menyebutkan temperatur gas buang akan meningkat seiring kenaikan excess air sedangkan efisiensi boiler akan berkurang.…”

“…Temperatur gas buang yang semakin tinggi juga akan menurunkan efisiensi termal pembangkit karena akan membuang lebih banyak panas ke udara luar. Sungur, et al [14] dan Ghritlahre, et al [15] juga mendapatkan hal yang sama. Gambar 8.…”