High performance steam cogeneration (proof-of-concept phases). Phase 2, HRSG 500-hour test report: Final report

Recent advances in small once-through Alloy 800 steam generators, improved materials technology, and application of small industrial gas turbine technology to steam turbine cogeneration offers the potential to make a step increase in steam temperature from around 1000{degree}F, where industry has been for almost fifty years, to 1500{degree}F. In small cogeneration systems, it is economically practical to introduce new technology and make a step change in temperature where it may not be possible (given the regulatory environment and economic risk) for a major change in steam temperature to be introduced in the hundreds of megawatt size of an electric utility. Increasing the peak steam temperature in a steam turbine cycle allows more work to be extracted or electrical power to be generated from a given quantity of heat input. Figure 1 plots steam efficiency as a function of superheat steam temperature and pressure for a turbine-back pressure of 166 psia. This figure clearly shows that increasing the steam conditions from the typical current practice of 900{degree}F and 900 psia to 1500{degree}F and 1500 psia will increase the steam cycle efficiency by 53%. The combination of higher cycle efficiency with an advanced high efficiency steam turbine design provides a substantial increase in turbine output power for a given steam flowrate. The output of this advanced high temperature steam turbine is approximately twice that of a current industrial practive turbine for the same turbine flowrate as seen in Figure 2.