Thermodynamic Performance Analyses of Mixed Gas-Steam Cycle (2): A Case Study of Aeroderivative Gas Turbine

Author(s):  
Kirk Hanawa

There are a plenty of proposals to aim the gas turbine cycle thermal efficiency of 60%, such as “Steam-Cooled H-Tech. Combined Cycle”, “Methanol Conversion Regenerative Gas Turbine”, “Kalina Cycle” etc.*1, *2, *4, *5, *6, *7 This paper discusses the predicted performance behaviors of an assumed aircraft-derivative GT of 60MW, when applying into mixed gas-steam cycles like STIG, ISTIG(Intercooled Steam Injection GT) with reasonable minor modifications from the assumed gas turbine. By making case studies of steam-injected binary cycles according to the established analyses method in Part (1), typical calculation results for getting 60% efficiency are presented. The water-injected at LPC, ISTIG cycle is equivalent or superior to other improvement ideas, offering several features listed below. 1) Unnecessary to have a bottoming cycle, saving a lot of investment for the related equipment 2) Quick and stable response for changing duty load, by injecting metered water and steam without air holding vessels like water-cooled heat exchangers

Author(s):  
Kirk Hanawa

Many ideas were proposed to aim the generation thermal efficiency up to 60%, such as “Steam-Cooled H-Tech. Combined Cycle”, “Methanol Conversion Regenerative Gas Turbine”, “Kalina Cycle” etc. The target thermal efficiency of 60% based upon LHV, could be also attained, when applying mixed gas-steam cycle like ISTIG and/or GAS3D for advanced aeroderivative gas turbines, which comprise of multiple shafts with overall pressure ratio more than 50, and TIT more than 2600 F (1700 K). It might be meaningful to evaluate existing aeroderivative gas turbines like LM6000 etc. by applying such a improving concept, as the more advanced gas turbines to be derived from GE90, PW4000, and Trent800 are not available to date for land applications. The intercooled ICAD GT of 77 MW was adopted as a base engine, and it was derived that the water /steam-injected WI/GAS3D GT version could produce 106 MW with 56% thermal efficiency, and it must be emphasized that the power curve in variation with ambient temperature is very flat than conventional GT plants.


Author(s):  
R Cai

It is shown that the classical recuperator effectiveness is not an appropriate evaluation criterion for the gas turbine recuperator or a suitable independent thermodynamic parameter of the recuperative gas turbine cycle. Another parameter—the average heat transfer temperature difference in the recuperator—is recommended as the new criterion instead of the recuperator effectiveness. Therefore, the original classical analysis results of the recuperative gas turbine cycle are also inappropriate and it is necessary to give a new analysis. In this paper, the analytical expressions of the simple recuperative cycle efficiency and the optimum pressure ratio based on the new criterion are derived from general simplified assumptions. Some typical calculation results are also presented. With this new criterion, the optimum pressure ratio values for efficiency of a simple recuperative gas turbine cycle do not vary very much with the temperature ratio and are approximately equal to 3, much lower than the figures generally recognized before. A similar analysis for the recuperative gas turbine cycle with intercooler and reheater and an analysis ensuring approximately constant recuperator heat transfer area per unit power output are given also.


Author(s):  
Olav Bolland ◽  
Jan Fredrik Stadaas

Combined cycles have gained widespread acceptance as the most efficient utilization of the gas turbine for power generation, particularly for large plants. A variety of alternatives to the combined cycle that recover exhaust gas heat for re-use within the gas turbine engine have been proposed and some have been commercially successful in small to medium plants. Most notable has been the steam injected, high-pressure aero-derivatives in sizes up to about 50 MW. Many permutations and combinations of water injection, steam injection, and recuperation, with or without intercooling, have been shown to offer the potential for efficiency improvements in certain ranges of gas turbine cycle design parameters. A detailed, general model that represents the gas turbine with turbine cooling has been developed. The model is intended for use in cycle analysis applications. Suitable choice of a few technology description parameters enables the model to accurately represent the performance of actual gas turbine engines of different technology classes. The model is applied to compute the performance of combined cycles as well as that of three alternatives. These include the simple cycle, the steam injected cycle and the dual-recuperated intercooled aftercooled steam injected cycle (DRIASI cycle). The comparisons are based on state-of-the-art gas turbine technology and cycle parameters in four classes: large industrial (123–158 MW), medium industrial (38–60 MW), aeroderivatives (21–41 MW) and small industrial (4–6 MW). The combined cycle’s main design parameters for each size range are in the present work selected for computational purposes to conform with practical constraints. For the small systems, the proposed development of the gas turbine cycle, the DRIASI cycle, are found to provide efficiencies comparable or superior to combined cycles, and superior to steam injected cycles. For the medium systems, combined cycles provide the highest efficiencies but can be challenged by the DRIASI cycle. For the largest systems, the combined cycle was found to be superior to all of the alternative gas turbine based cycles considered in this study.


1995 ◽  
Vol 117 (1) ◽  
pp. 138-145 ◽  
Author(s):  
O. Bolland ◽  
J. F. Stadaas

Combined cycles have gained widespread acceptance as the most efficient utilization of the gas turbine for power generation, particularly for large plants. A variety of alternatives to the combined cycle that recover exhaust gas heat for re-use within the gas turbine engine have been proposed and some have been commercially successful in small to medium plants. Most notable have been the steam-injected, high-pressure aeroderivatives in sizes up to about 50 MW. Many permutations and combinations of water injection, steam injection, and recuperation, with or without intercooling, have been shown to offer the potential for efficiency improvements in certain ranges of gas turbine cycle design parameters. A detailed, general model that represents the gas turbine with turbine cooling has been developed. The model is intended for use in cycle analysis applications. Suitable choice of a few technology description parameters enables the model to represent accurately the performance of actual gas turbine engines of different technology classes. The model is applied to compute the performance of combined cycles as well as that of three alternatives. These include the simple cycle, the steam-injected cycle, and the dual-recuperated intercooled aftercooled steam-injected cycle (DRIASI cycle). The comparisons are based on state-of-the-art gas turbine technology and cycle parameters in four classes: large industrial (123–158 MW), medium industrial (38–60 MW), aeroderivatives (21–41 MW), and small industrial (4–6 MW). The combined cycle’s main design parameters for each size range are in the present work selected for computational purposes to conform with practical constraints. For the small systems, the proposed development of the gas turbine cycle, the DRIASI cycle, are found to provide efficiencies comparable or superior to combined cycles, and superior to steam-injected cycles. For the medium systems, combined cycles provide the highest efficiencies but can be challenged by the DRIASI cycle. For the largest systems, the combined cycle was found to be superior to all of the alternative gas turbine based cycles considered in this study.


2015 ◽  
Vol 5 (2) ◽  
pp. 89
Author(s):  
Munzer S. Y. Ebaid ◽  
Qusai Z. Al-hamdan

<p class="1Body">Several modifications have been made to the simple gas turbine cycle in order to increase its thermal efficiency but within the thermal and mechanical stress constrain, the efficiency still ranges between 38 and 42%. The concept of using combined cycle power or CPP plant would be more attractive in hot countries than the combined heat and power or CHP plant. The current work deals with the performance of different configurations of the gas turbine engine operating as a part of the combined cycle power plant. The results showed that the maximum CPP cycle efficiency would be at a point for which the gas turbine cycle would have neither its maximum efficiency nor its maximum specific work output. It has been shown that supplementary heating or gas turbine reheating would decrease the CPP cycle efficiency; hence, it could only be justified at low gas turbine inlet temperatures. Also it has been shown that although gas turbine intercooling would enhance the performance of the gas turbine cycle, it would have only a slight effect on the CPP cycle performance.</p>


1984 ◽  
Vol 106 (3) ◽  
pp. 699-702 ◽  
Author(s):  
R. Digumarthi ◽  
Chung-Nan Chang

The Cheng-Cycle turbine engine is a superheated steam injected gas turbine cycle system. This work is based on the Garrett 831 gas turbine. The development effort involved the design and manufacture of an experimental heat recovery steam generator, a steam injection system, and system controls. Measured performance data indicate the 26 percent efficiency improvement has been obtained compared to that of the basic turbine engine at its continuous power rating.


Author(s):  
Isao Minatsuki ◽  
Sunao Oyama ◽  
Yorikata Mizokami ◽  
Bernard Ballot

In the world now, several types of indirect system concept have been investigated for the High Temperature Gas cooled Reactor power plant (HTGR). From a point of optimization of HTGR, it is important to investigate and to compare their power conversion systems from a technical and an economical view point. In the first step of this study, an indirect steam cycle (ID-SC), an indirect gas turbine cycle (ID-GT), an indirect gas turbine combined cycle (ID-CCGT) and a direct gas turbine cycle (D-GT) has been chosen as the systems to be compared. The followings are chosen items for comparison analysis: a) Plant efficiency; b) Amount of commodities (which can estimate capital cost); c) Flexibility of reactor core design; d) Technical issues to be developed; e) Compatibility with hydrogen production system, etc. And for the second step, as the system optimization study among the selected system, sensitiveness to plant efficiency by changing the inlet and the outlet temperature of reactor core has been investigated from an economical and plant efficiency point of view.


Author(s):  
Anoop Kumar Shukla ◽  
Onkar Singh

Gas/steam combined cycle power plants are extensively used for power generation across the world. Today’s power plant operators are persistently requesting enhancement in performance. As a result, the rigour of thermodynamic design and optimization has grown tremendously. To enhance the gas turbine thermal efficiency and specific power output, the research and development work has centered on improving firing temperature, cycle pressure ratio, adopting improved component design, cooling and combustion technologies, and advanced materials and employing integrated system (e.g. combined cycles, intercooling, recuperation, reheat, chemical recuperation). In this paper a study is conducted for combining three systems namely inlet fogging, steam injection in combustor, and film cooling of gas turbine blade for performance enhancement of gas/steam combined cycle power plant. The evaluation of the integrated effect of inlet fogging, steam injection and film cooling on the gas turbine cycle performance is undertaken here. Study involves thermodynamic modeling of gas/steam combined cycle system based on the first law of thermodynamics. The results obtained based on modeling have been presented and analyzed through graphical depiction of variations in efficiency, specific work output, cycle pressure ratio, inlet air temperature & density variation, turbine inlet temperature, specific fuel consumption etc.


Author(s):  
Ivan G. Rice

Interest in the reheat-gas turbine (RHGT) as a way to improve combined-cycle efficiency is gaining momentum. Compression intercooling makes it possible to readily increase the reheat-gas-turbine cycle-pressure ratio and at the same time increase gas-turbine output; but at the expense of some combined-cycle efficiency and mechanical complexity. This paper presents a thermodynamic analysis of the intercooled cycle and pinpoints the proper intercooling pressure range for minimum combined-cycle-efficiency loss. At the end of the paper two-intercooled reheat-gas-turbine configurations are presented.


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