Optimization of an integrated solar combined cycle

Abstract

In this paper, combined cycle (CC) power block parameters are optimized for its application coupled to concentrating solar power (CSP) plant. CSP hybrid plant is based on pressurized air receiver technology using natural gas assisted burner while the CC power block consists on high temperature open air Brayton cycle connected to bottoming steam Rankine cycle. Due to plant layout flexibility introduced by CC arrangements, three preferred configurations will be analyzed and optimized based on the intermediate pressure levels of the bottoming cycle. Benefits and drawbacks of each configuration will be discussed along the paper and the optimum solution will be proposed as the reference power block for electricity production at Integrated Solar Combined Cycle (ISCC) power plants. Results demonstrate that using current solar air receiver technology the system efficiency is far (around 47%) from the one expected from modern commercial CC systems (nearly 60%). The lower power cycle efficiency found was mainly based on pressure restrictions (below 6 bar) imposed by current air receiver designs what also implied lower temperature for the gas turbine.