scholarly journals Investigation of the Heat Transfer in High Temperature Gas Turbine Vanes

Author(s):  
Tomohiko Sato ◽  
Kenichiro Takeishi

The demand for higher efficiency, higher temperature industrial gas turbines used for the combined cycle plants has increased. The key technology of such high-temperature gas turbines with a turbine inlet temperature of 1300°C is the development of reliable air-cooled turbine vanes and blades. The life prediction of such air-cooled turbine vanes is strongly dependent on an accurate prediction of the metal temperature. The problem of temperature prediction is essentially one of obtaining the convective heat transfer boundary conditions on the external and internal surfaces of the vane. In this paper, typical heat transfer data which are indispensable for the analysis, are presented. Improvement of the temperature prediction accuracy within 25°C, the final goal, is sought by feeding the discrepancy between the cascade test and the analysis back into the fundamental heat transfer tests.

Author(s):  
Colin F. McDonald

With the capability of burning a variety of fossil fuels, giving high thermal efficiency, and operating with low emissions, the gas turbine is becoming a major prime-mover for a wide spectrum of applications. Almost three decades ago two experimental projects were undertaken in which gas turbines were actually operated with heat from nuclear reactors. In retrospect, these systems were ahead of their time in terms of technology readiness, and prospects of the practical coupling of a gas turbine with a nuclear heat source towards the realization of a high efficiency, pollutant free, dry-cooled power plant has remained a long-term goal, which has been periodically studied in the last twenty years. Technology advancements in both high temperature gas-cooled reactors, and gas turbines now make the concept of a nuclear gas turbine plant realizable. Two possible plant concepts are highlighted in this paper, (1) a direct cycle system involving the integration of a closed-cycle helium gas turbine with a modular high temperature gas cooled reactor (MHTGR), and (2) the utilization of a conventional and proven combined cycle gas turbine, again with the MHTGR, but now involving the use of secondary (helium) and tertiary (air) loops. The open cycle system is more equipment intensive and places demanding requirements on the very high temperature heat exchangers, but has the merit of being able to utilize a conventional combined cycle turbo-generator set. In this paper both power plant concepts are put into perspective in terms of categorizing the most suitable applications, highlighting their major features and characteristics, and identifying the technology requirements. The author would like to dedicate this paper to the late Professor Karl Bammert who actively supported deployment of the closed-cycle gas turbine for several decades with a variety of heat sources including fossil, solar, and nuclear systems.


Author(s):  
Xinhe Qu ◽  
Xiaoyong Yang ◽  
Jie Wang

High temperature gas cooled reactor (HTGR) which is one of generation IV reactor has been widely given attention in many countries since the sixties of the last century because of its inherent safety and high efficiency. Currently, the HTGR commonly uses regenerative Brayton cycle. However, as reactor outlet temperature (ROT) rising, regenerative Brayton cycle has a higher reactor inlet temperature (RIT) than 500°C and is limited by reactor materials. Combined cycle of HTGR not only can solve the problem of high RIT, but also can get a higher cycle efficiency than 50%. In this paper an accurate model of combined cycle consisting of topping Brayton cycle, bottoming Rankine cycle and heat recovery steam generator (HRSG) was established. In terms of new model of combined cycle, this paper analyzed the main properties of simple combined cycle. And put forward two optimization schemes improving the cycle efficiency of combined cycle.


1980 ◽  
Author(s):  
R. L. Graves

The difficulties encountered in past and present efforts to operate direct coal-fired gas turbines are substantial. Hence the development effort required to assure a reliable, high-temperature pressurized fluidized bed (PFBC) combined cycle may be very expensive and time consuming. It is, therefore, important that the benefit of achieving high-temperature operation, which is primarily increased efficiency, be clearly understood at the outset of such a development program. This study characterizes the effects of PFBC temperature and pressure on plant efficiency over a wide range of values. There is an approximate three percentage point advantage by operating at a gas turbine inlet temperature of 870 C (1600 F) instead of 538 C (1000 F). Optimum pressure varies with the gas turbine inlet temperature, but ranges from 0.4–1.0 MPa (4–10 atm). An alternate PFBC cycle offering high efficiency at a peak temperature of about 650 C (1200 F) is also discussed.


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