Keywords: regenerative Rankine cycle, absorption heat pumps, absorption heat transformers, simulation, exergy analysis, performance improvement, absorption heat boosters, LP turbines, low pressure turbines, feedwater heating
Improvement of regenerative Rankine cycle using absorption heat boosters
In the present work, a new technique is proposed for feedwater heating in Low Pressure (LP) turbine section of regenerative Rankine cycle. Main objective of this technique is to minimise exergy destruction in feedwater heating. The proposed technique comprised of using absorption heat boosters i.e. Absorption Heat Pump (AHP) and Absorption Heat Transformer (AHT) with LiBr–water as the working fluid. Heat booster consumes heat in the form of low quality steam from LP turbine, deliver it at better quality in absorber, and in some configuration, condenser. This heat is used for feedwater heating, which results in reduction in exergy destruction in the process. Various configurations of LP turbine section with absorption heat booster have been simulated. Results show that overall increased power output as high as 0.54% from LP turbine can be obtained. Exergy analysis of LP turbine section with heat booster shows that exergy saved through this technique get transformed into equal amount of additional power output.