Applying Kalina Technology to a Bottoming Cycle for Utility Combined Cycles

A new power generation technology often referred to as the Kalina cycle, is being developed as a direct replacement for the Rankine steam cycle. It may be applied to any thermal heat source, low or high temperature. Among several Kalina cycle variations there is one that is particularly well suited as a bottoming cycle for utility combined cycle applications. It is the subject of this paper. Using an ammonia/water mixture as the working fluid and a condensing system based on absorption refrigeration principles the Kalina bottoming cycle outperforms a triple pressure steam cycle by 16 percent. Additionally, this version of the Kalina cycle is characterized by an intercooling feature between turbine stages, diametrically opposite to normal reheating practice in steam plants. Energy and mass balances are presented for a 200 MWe Kalina bottoming cycle. Kalina cycle performance is compared to a triple pressure steam plant. At a peak cycle temperature of 950° F the Kalina plant produces 223.5 MW vs. 192.6 MW for the triple pressure steam plant, an improvement of 16.0 percent. Reducing the economizer pinch point to 15° F results in a performance improvement in excess of 30 percent.