Thermodynamic Analysis of Rankine-Kalina Combined Cycle

Abstract

Efficiency enhancement in a low grade fuel fired power plant is one of the challenging tasks for researchers. In a low grade fuel fired power plant even a fraction of a percentage improvement in efficiency implies a huge savings in annual fuel costs. Mainly, the poor vapor quality of steam in the last stages of an LP turbine and energy loss in the condenser deteriorates the Rankine steam cycle performance. Reducing the amount of energy loss in the condenser and minimizing two-phase fluid operation in last stages of the LP turbine can substantially improve the cycle efficiency. The objective is to reduce the energy losses and to enhance the system performance. In this work a direct-fired 82.2 MWfuel biomass fueled condensing power Rankine cycle is considered for performance improvement. Energy and exergy analysis are performed for the proposed Rankine-Kalina combined cycle (RKC). The RKC cycle produces higher power output and is more efficient than a Rankine steam cycle.

Keywords

• Rankine-Kalina combined cycle, low grade fuel, biomass