scholarly journals Thermal Impact of Operating Conditions on the Performance of a Combined Cycle Gas Turbine

Author(s):  
Thamir K. Ibrahim ◽  
M.M. Rahman

The combined cycle gas-turbine (CCGT) power plant is a highly developed technology which generates electrical power at high efficiencies. The first law of thermodynamics is used for energy analysis of the performance of the CCGT plant. The effects of varying the operating conditions (ambient temperature, compression ratio, turbine inlet temperature, isentropic compressor and turbine efficiencies, and mass flow rate of steam) on the performance of the CCGT (overall efficiency and total output power) were investigated. The programming of the performance model for CCGT was developed utilizing MATLAB software. The simulation results for CCGT show that the overall efficiency increases with increases in the compression ratio and turbine inlet temperature and with decreases in ambient temperature. The total power output increases with increases in the compression ratio, ambient temperature, and turbine inlet temperature. The peak overall efficiency was reached with a higher compression ratio and low ambient temperature. The overall efficiencies for CCGT were very high compared to the thermal efficiency of GT plants. The overall thermal efficiency of the CCGT quoted was around 57%; hence, the compression ratios, ambient temperature, turbine inlet temperature, isentropic compressor and turbine efficiencies, and mass flow rate of steam have a strong influence on the overall performance of the CCGT cycle.

2013 ◽  
Vol 17 (2) ◽  
pp. 497-508 ◽  
Author(s):  
Thamir Ibrahim ◽  
M.M. Rahman

The thermodynamic analyses of the triple-pressure reheat combined cycle gas turbines with duct burner are presented and discussed in this paper. The overall performance of a combined cycle gas turbine power plant is influenced by the ambient temperature, compression ratio and turbine inlet temperature. These parameters affect the overall thermal efficiency, power output and the heat-rate. In this study a thermodynamic model was development on an existing actual combined cycle gas turbine (CCGT) (In this case study, an effort has been made to enhance the performance of the CCGT through a parametric study using a thermodynamic analysis. The effect of ambient temperature and operation parameter, including compression ratio and turbine inlet temperature, on the overall performance of CCGT are investigated. The code of the performance model for CCGT power plant was developed utilizing the THERMOFLEX software. The simulating results show that the total power output and overall efficiency of a CCGT decrease with increase the ambient temperature because increase the consumption power in the air compressor of a GT. The totals power of a CCGT decreases with increase the compression rate, while the overall efficiency of a CCGT increases with increase the compression ratio to 21, after that the overall efficiency will go down. Far there more the turbine inlet temperature increases the both total power and overall efficiency increase, so the turbine inlet temperature has a strong effect on the overall performance of CCGT power plant. Also the simulation model give a good result compared with MARAFIQ CCGT power plant. With these variables, the turbine inlet temperature causes the greatest overall performance variation.


2011 ◽  
Vol 189-193 ◽  
pp. 3007-3013 ◽  
Author(s):  
M.M. Rahman ◽  
Thamir K. Ibrahim ◽  
K. Kadirgama ◽  
R. Mamat ◽  
Rosli A. Bakar

This paper presents the effect of ambient temperature and operation conditions (compression ratio, turbine inlet temperature, air to fuel ratio and efficiency of compressor and turbine) on the performance of gas turbine power plant. The computational model was developed utilizing the MATLAB codes. Turbine work found to be decreases as ambient temperature increases as well as the thermal efficiency decreases. It can be seen that the thermal efficiency increases linearly with increases of compression ratio while decreases of ambient temperature. The specific fuel consumption increases with increases of ambient temperature and lower turbine inlet temperature. The effect of variation of SFC is more significance at higher ambient temperature than lower temperature. It is observed that the thermal efficiency linearly increases at lower compressor ratio as well as higher turbine inlet temperature until certain value of compression ratio. The variation of thermal efficiency is more significance at higher compression ratio and lower turbine inlet temperature. Even though at lower turbine inlet temperature is decrement the thermal efficiency dramatically and the SFC decreases linearly with increases of compression ratio and turbine inlet temperature at lower range until certain value then increases dramatically for lower turbine inlet temperature.


Author(s):  
Seong Kuk Cho ◽  
Minseok Kim ◽  
Seungjoon Baik ◽  
Yoonhan Ahn ◽  
Jeong Ik Lee

The supercritical CO2 (S-CO2) power cycle has been receiving attention as one of the future power cycle technology because of its compact configuration and high thermal efficiency at relatively low turbine inlet temperature ranges (450∼750°C). Thus, this low turbine inlet temperature can be suitable for the bottoming cycle of a combined cycle gas turbine because its exhaust temperature range is approximately 500∼600°C. The natural gas combined cycle power plant utilizes mainly steam Rankine cycle as a bottoming cycle to recover waste heat from a gas turbine. To improve the current situation with the S-CO2 power cycle technology, the research team collected various S-CO2 cycle layouts and compared each performance. Finally, seven cycle layouts were selected as a bottoming power system. In terms of the net work, each cycle was evaluated while the mass flow rate, the split flow rate and the minimum pressure were changed. The existing well-known S-CO2 cycle layouts are unsuitable for the purpose of a waste heat recovery system because it is specialized for a nuclear application. Therefore, the concept to combine two S-CO2 cycles was suggested in this paper. Also the complex single S-CO2 cycles are included in the study to explore its potential. As a result, the net work of the concept to combine two S-CO2 cycles was lower than that of the performance of the reference steam cycle. On the other hand, the cascade S-CO2 Brayton cycle 3 which is one of the complex single cycles was the only cycle to be superior to the reference steam cycle. This result shows the possibility of the S-CO2 bottoming cycle if component technologies become mature enough to realize the assumptions in this paper.


Author(s):  
Katsuyoshi Tada ◽  
Kei Inoue ◽  
Tomo Kawakami ◽  
Keijiro Saitoh ◽  
Satoshi Tanimura

Gas-turbine combined-cycle (GTCC) power generation is clean and efficient, and its demand will increase in the future from economic and social perspectives. Raising turbine inlet temperature is an effective way to increase combined cycle efficiency and contributes to global environmental conservation by reducing CO2 emissions and preventing global warming. However, increasing turbine inlet temperature can lead to the increase of NOx emissions, depletion of the ozone layer and generation of photochemical smog. To deal with this issue, MHPS (MITSUBISHI HITACHI POWER SYSTEMS) and MHI (MITSUBISHI HEAVY INDUSTRIES) have developed Dry Low NOx (DLN) combustion techniques for high temperature gas turbines. In addition, fuel flexibility is one of the most important features for DLN combustors to meet the requirement of the gas turbine market. MHPS and MHI have demonstrated DLN combustor fuel flexibility with natural gas (NG) fuels that have a large Wobbe Index variation, a Hydrogen-NG mixture, and crude oils.


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):  
Francesco Fantozzi ◽  
Bruno D’Alessandro ◽  
Pietro Bartocci ◽  
Umberto Desideri ◽  
Gianni Bidini

The Integrated Pyrolysis Regenerated Plant (IPRP) concept is based on a rotary kiln pyrolyzer that converts biomass or wastes (B&W) in a rich gas used to fuel a gas turbine (GT); the combustion of pyrolysis by-products (char or tar), is used to provide heat to the pyrolyzer together with the GT exhaust gases. The IPRP concept was modelled through an homemade software, that utilizes thermodynamic relations, energy balances and data available in the Literature for BW pyrolysis products. The analysis was carried out investigating the influence on the plant performances of main thermodynamic parameters like the Turbine Inlet Temperature (TIT), the Regeneration Ratio (RR) and the manometric compression ratio (β) of the gas turbine; when data on the pyrolysis process where available for different pyrolysis temperature, also the different pyrolysis temperature (TP) was considered. Finally, data obtained from the analysis where collected for the typical parameters of different GT sizes, namely the manometric compression ratio and the turbine inlet temperature. For the other parameters, where considered the ones that give the highest efficiencies. The paper shows the IPRP efficiency, when fuelled with different biomass or wastes materials and for different GT (plant) size.


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.


2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Lihuang Luo ◽  
Hong Gao ◽  
Chao Liu ◽  
Xiaoxiao Xu

A combined cycle that combines AWM cycle with a nuclear closed Brayton cycle is proposed to recover the waste heat rejected from the precooler of a nuclear closed Brayton cycle in this paper. The detailed thermodynamic and economic analyses are carried out for the combined cycle. The effects of several important parameters, such as the absorber pressure, the turbine inlet pressure, the turbine inlet temperature, the ammonia mass fraction, and the ambient temperature, are investigated. The combined cycle performance is also optimized based on a multiobjective function. Compared with the closed Brayton cycle, the optimized power output and overall efficiency of the combined cycle are higher by 2.41% and 2.43%, respectively. The optimized LEC of the combined cycle is 0.73% lower than that of the closed Brayton cycle.


2017 ◽  
Author(s):  
Waleed El-Damaty ◽  
Mohamed Gadalla

With the current increase in electricity consumption and energy demand, most of the research focus is shifted towards the means of increasing the power plants efficiency in order to produce more electricity by using as less fuel as possible. Gas turbine power plants specifically have been under the study in the recent years due to its feasibility, low capital cost, simple design, compact size and higher efficiency compared to steam turbine power plants. There are a lot of operating conditions that affect the performance of the gas turbine which includes the inlet air climatic conditions, mass flow rate and the turbine inlet temperature. Many improvements and enhancements became applicable through the advancement in the material and cooling technologies. Cooling techniques could be used to cool the inlet air entering the compressor by utilizing evaporative coolers and mechanical chillers, and to cool the turbine blades in order to avoid a decline in the life of turbine blades due to unwanted exposure to thermal stresses and oxidation. Internal convection cooling, film cooling and transpiration cooling are the three main techniques that can be used in the process of turbine blades cooling. The main objective of this proposal is to improve the durability and performance of gas turbine power plants by proposing the usage of integrated system of solid desiccant with Maisotsenko cooler in the turbine blade cooling and inlet air cooling processes. Four configurations were presented and the results were an increase in the efficiency of the gas turbine cycle for all the cases specially the two stage Maisotsenko desiccant cooling system where the efficiency increased from 33.33% to 34.17% as well as maintaining the turbine inlet temperature at a desired level of 1500°K.


2021 ◽  
Author(s):  
Rishabh Shrivastava ◽  
Ankush Kapoor ◽  
Stuti Kaushal ◽  
Amit Yadav ◽  
Pavankumar Vodnala

Abstract Gas turbine blades and vanes face very severe operating conditions - high temperature and pressure which necessitates the creation of complex cooling and component designs, resulting in high computational cost. The ability to predict cyclic failure in these components is therefore a critical activity that has been historically performed using 3D commercial finite element (FE) codes for baseload conditions. However, these codes take substantial time and resources which restricts their application in failure prediction at variable operating conditions. Newer data-driven techniques such as machine learning (ML) provide a valuable tool that can be utilized to predict the occurrence of cyclic failure for these conditions with minimal time and resource requirement. In this paper, a machine learning based surrogate model is developed to predict the cyclic failure of a radially cooled turbine blade. The features used as input to machine learning model are turbine inlet temperature, coolant inlet temperature, hot gas mass flow rate, cooling air mass flow rate and blade materials. The output for the model is a binary variable depicting the incident of component failure. 70% of the FE data points are used to train the ML model while the remaining are used for testing. A comparative study between Logistic Regression, Random Forest, K-nearest neighbor, and Support Vector Machine (SVM) was performed to select the most accurate algorithm for the classification model. Finally, the results show that the Random Forest and SVM algorithms predicts failure with the highest f-1 score of 0.92. The model also demonstrates that Turbine Inlet temperature has the highest importance amongst the input features followed by blade material. Additionally, this methodology offers a tremendous advantage for failure prediction by reducing analysis time from multiple hours to a few seconds, rendering this technique especially beneficial for time sensitive business decisions in the gas turbine industry.


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