scholarly journals Gas Turbine and Combined Cycle Technologies for Power and Efficiency Enhancement in Power Plants

Author(s):  
Meherwan P. Boyce ◽  
Cyrus B. Meher-Homji ◽  
A. N. Lakshminarasimha

A wide variety of gas turbine based cycles exist in the market today with several technologies being promoted by individual Original Equipment Manufacturers. This paper is focused on providing users with a conceptual framework within which to view these cycles and choose suitable options for their needs. A basic parametric analysis is provided to show the interdependency of Turbine Inlet Temperature (TIT) and Pressure Ratio on cycle efficiency and specific work.

Author(s):  
B W Martin ◽  
A Brown ◽  
M Finnis

This paper continues the computational invcstigalion of optimum performance of a gas turbine configuration incorporating a gas generator, previously reported by the authors. Even for contemporary pressure ratios not previously considered, there appears to be no advantage in prebleeding the coolant air, and within the range considered, as previously found, the amount of coolant preheating has only a secondary effect on maximum engine efficiency. This is also true of the influence of allowable mean blade temperature on maximum engine efficiency, but both factors do have a pronounced effect on the optimum coolant and where maximum cycle efficiency is primarily determined by compressor pressure ratio and component isen-tropic efficiencies. The specific work output is confirmed under optimum conditions to be an almost linear function of the compressor turbine inlet temperature.


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>


Author(s):  
Hideto Moritsuka

In order to estimate the possibility to improve thermal efficiency of power generation use gas turbine combined cycle power generation system, benefits of employing the advanced gas turbine technologies proposed here have been made clear based on the recently developed 1500C-class steam cooling gas turbine and 1300C-class reheat cycle gas turbine combined cycle power generation systems. In addition, methane reforming cooling method and NO reducing catalytic reheater are proposed. Based on these findings, the Maximized efficiency Optimized Reheat cycle Innovative Gas Turbine Combined cycle (MORITC) Power Generation System with the most effective combination of advanced technologies and the new devices have been proposed. In case of the proposed reheat cycle gas turbine with pressure ratio being 55, the high pressure turbine inlet temperature being 1700C, the low pressure turbine inlet temperature being 800C, combined with the ultra super critical pressure, double reheat type heat recovery Rankine cycle, the thermal efficiency of combined cycle are expected approximately 66.7% (LHV, generator end).


Author(s):  
Mayank Maheshwari ◽  
Onkar Singh

Abstract Performance of gas/steam combined cycle power plants relies upon the performance exhibited by both gas based topping cycle and steam based bottoming cycle. Therefore, the measures for improving the performance of the gas turbine cycle and steam bottoming cycle eventually result in overall combined cycle performance enhancement. Gas turbine cooling medium affects the cooling efficacy. Amongst different parameters in the steam bottoming cycle, the deaerator parameter also plays its role in cycle performance. The present study analyzes the effect of deaerator’s operating pressure being varied from 1.6 bar to 2.2 bar in different configurations of simple and reheat gas/steam combined cycle with different cooling medium for fixed cycle pressure ratio of 40, turbine inlet temperature of 2000 K and ambient temperature of 303 K with varying ammonia mass fraction from 0.6 to 0.9. Analysis of the results obtained for different combined cycle configuration shows that for the simple gas turbine and reheat gas turbine-based configurations, the maximum work output of 643.78 kJ/kg of air and 730.87 kJ/kg of air respectively for ammonia mass fraction of 0.6, cycle efficiency of 54.55% and 53.14% respectively at ammonia mass fraction of 0.7 and second law efficiency of 59.71% and 57.95% respectively at ammonia mass fraction of 0.7 is obtained for the configuration having triple pressure HRVG with ammonia-water turbine at high pressure and intermediate pressure and steam turbine operating at deaerator pressure of 1.6 bar.


Author(s):  
Onkar Singh ◽  
R. Yadav

Combined cycle based power plants and their development and application for energy efficient base load power generation necessitates enforced cooling to maintain the topping cycle gas turbine blade temperature at permissible levels, attributed to the increased turbine inlet temperature and compressor pressure ratio, for the improved performance and reliability of combined cycle. The mathematical model based on expansion path inside gas turbine considering dilution of mainstream and aerodynamic mixing losses for a range of cooling medium has been developed based on internal, film, transpiration cooling technologies and a combination of these. It is found that the appreciation of a cycle configuration as well as the optimum pressure ratio and peak temperature vary significantly with types of cooling technology adopted. Steam cooling for rotor appears to be a very potential cooling medium, when employed with an appropriate cooling technology. This paper deals with the thermodynamic analysis of turbine cooling using, different means of cooling i.e. air, water and steam.


Author(s):  
Hideto Moritsuka ◽  
Tomoharu Fujii ◽  
Takeshi Takahashi

The thermal efficiency of gas turbine combined cycle power generation plants increase significantly in accordance with turbine inlet temperature. Gas turbine combined cycle power plants operating at high turbine inlet temperature are popular as a main thermal power station among our electric power companies in Japan. Thus, gas turbine hot gas parts are working under extreme conditions which will strongly affect their lifetime as well as maintenance costs for repaired and replaced parts. To reduce the latter is of major importance to enhance cost effectiveness of the plant. This report describes a gas turbine maintenance management program of main hot gas parts (combustor chambers, transition peices, turbine 1st. stage nozzles and 1st. stage buckets) for management persons of gas turbine combined cycle power stations in order to obtain an optimal gas turbine maintenance schedule considering rotation, repair and replacement or exchange of those parts.


Author(s):  
Ibrahim Sinan Akmandor ◽  
O¨zhan O¨ksu¨z ◽  
Sec¸kin Go¨kaltun ◽  
Melih Han Bilgin

A new methodology is developed to find the optimal steam injection levels in simple and combined cycle gas turbine power plants. When steam injection process is being applied to simple cycle gas turbines, it is shown to offer many benefits, including increased power output and efficiency as well as reduced exhaust emissions. For combined cycle power plants, steam injection in the gas turbine, significantly decreases the amount of flow and energy through the steam turbine and the overall power output of the combined cycle is decreased. This study focuses on finding the maximum power output and efficiency of steam injected simple and combined cycle gas turbines. For that purpose, the thermodynamic cycle analysis and a genetic algorithm are linked within an automated design loop. The multi-parameter objective function is either based on the power output or on the overall thermal efficiency. NOx levels have also been taken into account in a third objective function denoted as steam injection effectiveness. The calculations are done for a wide range of parameters such as compressor pressure ratio, turbine inlet temperature, air and steam mass flow rates. Firstly, 6 widely used simple and combined cycle power plants performance are used as test cases for thermodynamic cycle validation. Secondly, gas turbine main parameters are modified to yield the maximum generator power and thermal efficiency. Finally, the effects of uniform crossover, creep mutation, different random number seeds, population size and the number of children per pair of parents on the performance of the genetic algorithm are studied. Parametric analyses show that application of high turbine inlet temperature, high air mass flow rate and no steam injection lead to high power and high combined cycle thermal efficiency. On the contrary, when NOx reduction is desired, steam injection is necessary. For simple cycle, almost full amount of steam injection is required to increase power and efficiency as well as to reduce NOx. Moreover, it is found that the compressor pressure ratio for high power output is significantly lower than the compressor pressure ratio that drives the high thermal efficiency.


Author(s):  
R. Yadav ◽  
Pradeep Kumar ◽  
Samir Saraswati

This paper presents a comparative study of first and second law thermodynamic analysis of combined and recuperated and non-recuperated steam injected gas turbine cycles. The analysis has been carried out by developing a computer code, which is based on the modeling of various elements of these cycles. The gas turbine chosen for the analysis is MS9001H developed recently by GE and the steam cycle is having a triple-pressure heat recovery steam generator with reheat. It has been observed that the combined cycle is superior to the steam injected cycle, however, the gap narrows down with increasing compressor pressure ratio and high value of turbine inlet temperature. The detailed exergy losses have been presented in various elements of combined and steam injected cycles.


Author(s):  
Feliciano Pava´n ◽  
Marco Romo ◽  
Juan Prince

The present paper is a thermodynamics analysis, i.e. both energy and exergy analyses for a natural gas based combined cycle power plant. The analysis was performed for an existing 240 MW plant, where the steam cycle reduces the irreversibilities during heat transfer from gas to water/steam. The effect of operating variables such as pressure ratio, gas turbine inlet temperature on the performance of combined cycle power plant has been investigated. The pressure ratio and maximum temperature (gas turbine inlet temperature) are identified as the dominant parameters having impact on the combined cycle plant performance. The work output of the topping cycle is found to increase with pressure ratio, while for the bottoming cycle it decreases. However, for the same gas turbine inlet temperature the overall work output of the combined cycle plant increases up to a certain pressure ratio, and thereafter not much increase is observed. The exergy losses of the individual components in the plant are evaluated based on second law of thermodynamics. The present results form a basis on which further work can be conducted to improve the performance of these units.


Author(s):  
A. F. Massardo ◽  
M. Scialò

The thermoeconomic analysis of gas turbine based cycles is presented and discussed in this paper. The thermoeconomic analysis has been performed using the ThermoEconomic Modular Program (TEMP V.5.0) developed by the Authors (Agazzani and Massardo, 1997). The modular structure of the code allows the thermoeconomic analysis for different scenarios (turbine inlet temperature, pressure ratio, fuel cost, installation costs, operating hours per year, etc.) of a large number of advanced gas turbine cycles to be obtained in a fast and reliable way. The simple cycle configuration results have been used to assess the cost functions and coefficient values. The results obtained for advanced gas turbine based cycles (intercooled, re-heated, regenerated and their combinations) are presented using new and useful representations: cost vs. efficiency, cost vs. specific work, and cost vs. pressure ratio. The results, including productive diagram configurations, are discussed in detail and compared to one another.


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