WASTE HEAT RECOVERY DRIVEN TURBOCHARGER SYSTEM FOR GAS TURBINE

This paper introduces a novel concept for power augmentation by waste heat recovery turbocharger system. The turbocharger system, coupled to an external air compressor, is driven by the exhaust gases waste heat. The air compressor then compresses additional air that will be injected into the gas turbine compressor discharge and boost the gas turbine power. As the heat recovery system drives the turbocharger with heat recovered from the exhaust gas stream, the power produced by the power generation system increases without decreasing the efficiency. Compressed air injection helps with resorting the missing gas turbine compressor air at high ambient temperatures and thus the compressed air injection is more suitable for gas turbines operating at hot ambient conditions. The paper also investigates utilizing the waste heat recovery turbocharger system at gas turbine part load operation for fuel saving and heat rate improvements. This paper analyzes the gas turbine simple cycle power improvements at different ambient conditions and compressed air injection percentage. The gas turbine power proved to increase by around 2% at 1% air injection and 10% at 5% air injection at high ambient temperatures 30 degrees C, 40 degrees C and 50 degrees C. Furthermore, the gas turbine heat rate improvement landed at 6.5% at 50 degrees C and 5% air injection. This study also compares the waste heat recovery system with other power augmentation technologies, namely the inlet mechanical chiller and the evaporative cooler. Compared to a gas turbine with waste heat recovery turbocharger air injection system at 5% air injection, the electrical chiller system increases the gas turbine heat rate by around 2% assuming chiller COP of 5. The waste heat recovery turbocharger system offers both power augmentation and heat rate improvements for simple cycle gas turbines. Additionally, this system can extend the hot gas path life by lowering the firing temperature without losing power.