Oxy-Fuel Gas Turbine, Gas Generator and Reheat Combustor Technology Development and Demonstration

Future fossil-fueled power generation systems will require carbon capture and sequestration to comply with government green house gas regulations. The three prime candidate technologies that capture carbon dioxide (CO₂) are pre-combustion, post-combustion and oxy-fuel combustion techniques. Clean Energy Systems, Inc. (CES) has recently demonstrated oxy-fuel technology applicable to gas turbines, gas generators, and reheat combustors at their 50MW_th research test facility located near Bakersfield, California. CES, in conjunction with Siemens Energy, Inc. and Florida Turbine Technologies, Inc. (FTT) have been working to develop and demonstrate turbomachinery systems that accommodate the inherent characteristics of oxy-fuel (O-F) working fluids. The team adopted an aggressive, but economical development approach to advance turbine technology towards early product realization; goals include incremental advances in power plant output and efficiency while minimizing capital costs and cost of electricity [1]. Proof-of-concept testing was completed via a 20MW_th oxy-fuel combustor at CES’s Kimberlina prototype power plant. Operability and performance limits were explored by burning a variety of fuels, including natural gas and (simulated) synthesis gas, over a wide range of conditions to generate a steam/CO₂ working fluid that was used to drive a turbo-generator. Successful demonstration led to the development of first generation zero-emission power plants (ZEPP). Fabrication and preliminary testing of 1^st generation ZEPP equipment has been completed at Kimberlina power plant (KPP) including two main system components, a large combustor (170MW_th) and a modified aeroderivative turbine (GE J79 turbine). Also, a reheat combustion system is being designed to improve plant efficiency. This will incorporate the combustion cans from the J79 engine, modified to accept the system’s steam/CO₂ working fluid. A single-can reheat combustor has been designed and tested to verify the viability and performance of an O-F reheater can. After several successful tests of the 1^st generation equipment, development started on 2^nd generation power plant systems. In this program, a Siemens SGT-900 gas turbine engine will be modified and utilized in a 200MW_e power plant. Like the 1^st generation system, the expander section of the engine will be used as an advanced intermediate pressure turbine and the can-annular combustor will be modified into a O-F reheat combustor. Design studies are being performed to define the modifications necessary to adapt the hardware to the thermal and structural demands of a steam/CO₂ drive gas including testing to characterize the materials behavior when exposed to the deleterious working environment. The results and challenges of 1^st and 2^nd generation oxy-fuel power plant system development are presented.