This paper presents an analysis of steam rates in steam-injected gas turbines (simple and reheat). In considering a gas turbine of this type, the steam-injection flow is separated from the main gas stream for analysis. Dalton’s and Avogadro’s laws of partial pressure and gas mixtures are applied. Results obtained provide for the accurate determination of heat input, gas expansion based on partial pressures, and heat-rejection steam-enthalpy points.
The reheat (RH) pressure can be appreciably increased by applying steam cooling to the gas-generator (GG) turbine blading which in turn allows a higher RH firing temperature for a fixed exhaust temperature. These factors increase gas turbine output and raise combined-cycle efficiency. The GG turbine blading will approach “uncooled expansion efficiency”. Eliminating cooling air increases the gas turbine RH pressure by 10.6 percent. When steam is used (injected) as the blade coolant, additional GG work is also developed which further increases the RH pressure by another 12.0 percent to yield a total increase of approximately 22.6 percent. The 38-cycle pressure ratio 2400° F (1316° C) TIT GG studied produces a respectable 6.5 power turbine expansion ratio. The higher pressure also noticeably reduces the physical size of the RH combustor. This paper presents an analysis of the RH pressure rise when applying steam to blade cooling.
High-temperature turbine technology (HTTT) when applied to the reheat-gas-turbine combined cycle (RHGT/CC) offers distinct advantages over the presently contemplated United States Department of Energy (DOE) HTTT simple-cycle gas-turbine combined cycle (SCGT/CC) being developed for gaseous fuel derived from coal. Specific improvements are: 1) higher combined-cycle efficiency, 2) higher specific output per unit of air flow, 3) less critical high-temperature nozzle-vane and rotating-blade surface area to be cooled, 4) less strategic high temperature metal material to be used, and 5) less overall cycle-cooling degradation allowing growth potential. New cooling techniques employing steam are required to accomplish these projections which necessitates advanced research and development and presently unavailable mathematical analytical approaches.
The reheat gas turbine cycle combined with the steam turbine Rankine cycle holds new promise of appreciably increasing power plant thermal efficiency. Apparently the cycle has been overlooked and thus neglected through the years. Research and development is being directed towards other gas turbine areas because of the world energy crunch; and in order to focus needed technical attention to the reheat cycle, this paper is presented, using logic and practical background of heat recovery boilers, steam turbines, gas turbines and the process industry. A critical analysis is presented establishing parameters of efficiency, cycle pressure ratio, firing temperature and output. Using the data developed, an analysis of an actual gas generator, the second generation LM5000, is applied with unique approaches to show that an overall 50 percent efficiency power plant can be developed using today’s known techniques and established base-load firing temperatures.
Complex open gas turbine cycles are analyzed by applying the heat balance method presented in Part I of this paper. Reheating, intercooling, regeneration, steam injection, and steam cooling are evaluated graphically to give a visual perspective of what takes place in terms of the overall heat balance when such complexities are introduced to the cycle. An example of a viable, new, intercooled regenerative cycle is given. A second example of a prototype reheat gas turbine is also included. The overall approach using the heat balance method can be applied to various cogeneration configurations when considering the more complex cycles of the future.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.