Application of Existing Turbomachinery for Zero Emissions Oxy-Fuel Power Systems

Abstract

Future fossil-fuel-based power generation systems must include decarbonizing technologies to capture and store (CCS) carbon dioxide (CO2). Oxy-fuel (O-F) combustion-based power systems are uniquely capable of capturing almost all CO2. In the O-F power plant cycle, fuel and nearly pure oxygen, delivered from an air separation unit (ASU), are burned to form a working fluid composed primarily of steam and CO2. Clean Energy Systems (CES), Siemens Energy, Inc. and Florida Turbine Technologies, Inc. (FIT) are jointly developing turbomachinery systems driven by O-F working fluids and have adopted a stepped development approach to advance the technology toward product realization through an initial proof-of-concept phase and subsequent development of 1st and 2nd generation power plant systems. Specific goals and objectives target incremental advancements of power plant efficiency and output while reducing capital costs and cost of electricity. In the initial proof-of-concept phase, bench-level research was performed on a primary combustion system. A 20MWth development gas generator was used to explore operability and performance limits while operating on a variety of fuels over a wide range of conditions. Further, the working fluid produced by this combustor was used to drive an existing turbine/generator set at CES’ Kimberlina prototype power plant located near Bakersfield, California. This paper summarizes the recent follow-on work to develop and demonstrate 1st and 2nd generation O-F power plant systems. Successful completion of the proof-of-concept phase led to the development of the 1st generation power plant system. Specific equipment required for this operation included a larger 170MWth combustor, which was constructed to produce additional power in this phase. An existing General Electric GE-J79 turbine was modified to extract power from this unit. All equipment required for this system has been assembled at CES’ Kimberlina power plant. In addition, a reheat combustion system is being developed to enhance the 1st generation power plant cycle. In a logical next step, a larger power output, increased-efficiency 2nd generation power plant system was defined. For this application, the Siemens SGT-900 gas turbine was selected as the basis for the Intermediate Pressure Turbine. Conceptual design studies were performed to identify the modifications needed in order to adapt the hardware to accept O-F drive gases. Specific challenges related to the mechanical design configuration, and thermal/structural behaviors of the system are delineated. Testing is being performed to characterize the behavior of materials when exposed to the steam/CO2 working fluid environment. Necessary development of long-lead items required for this system is also described.