Gas Turbines with Heat Exchanger and Water Injection in the Compressed Air

1970 ◽  
Vol 185 (1) ◽  
pp. 953-961 ◽  
Author(s):  
N Gašparović ◽  
J. G. Hellemans

Water injection into the compressed air between the compressor and the heat exchanger of a gas turbine plant represents only one of various possible methods of introducing water into a gas turbine cycle. With this process, it is advantageous to inject just sufficient water to produce saturation of the compressed air with water vapour. Assuming that the same size of heat exchanger is used, the following changes are introduced as compared with a gas turbine cycle without water injection. The efficiency is increased to an extent equivalent to raising the temperature at the turbine inlet by 100 degC. The gain in specific work is still greater. It attains values which can only be achieved with about 140 degC higher temperature at the turbine inlet. With a normal size of heat exchanger, the water consumption is about 6–8 per cent of the mass flow of air. This rate of consumption is not high enough to introduce any detrimental side effects in the cycle. Special water treatment is not necessary. The performance of existing designs or installations without a heat exchanger can be improved by adding a heat exchanger and water injection without necessitating any change in pressure ratio.

1987 ◽  
Vol 109 (1) ◽  
pp. 46-54 ◽  
Author(s):  
G. Cerri

Combined gas-steam cycles have been analyzed from the thermodynamic point of view. Suitable thermodynamics indices—explained in Appendix A—have been utilized. The parameters that most influence efficiency have been singled out and their ranges of variability have been specified. Calculations have been carried out—see Appendix B—taking into account the state of the art for gas turbines and the usual values for the quantities of steam cycles. The results are given. The maximal gas turbine temperature has been varied between 800°C and 1400°C. The gas turbine pressure ratio has been analyzed in the range of 2–24. Afterburning has also been taken into consideration. Maximal efficiency curves and the corresponding specific work curves (referred to the compressed air) related to the parameters of the analysis are given and discussed.


Author(s):  
G. Cerri

Combined gas-steam cycles have been analyzed from the thermodynamic point of view. Suitable thermodynamics indices — explained in Appendix A — have been utilized. The parameters that most influence efficiency have been singled out and their ranges of variability have been specified. Calculations have been carried out — see Appendix B — taking into account the state of the art for gas turbines and the usual values for the quantities of steam cycles. The results are given. The maximal gas turbine temperature has been varied between 800°C and 1400°C. The gas turbine pressure ratio has been analyzed in the range of 2–24. Afterburning has also been taken into consideration. Maximal efficiency curves and the corresponding specific work curves (referred to the compressed air) related to the parameters of the analysis are given and discussed.


Author(s):  
Uyioghosa Igie ◽  
Marco Abbondanza ◽  
Artur Szymański ◽  
Theoklis Nikolaidis

Industrial gas turbines are now required to operate more flexibly as a result of incentives and priorities given to renewable forms of energy. This study considers the extraction of compressed air from the gas turbine; it is implemented to store heat energy at periods of a surplus power supply and the reinjection at peak demand. Using an in-house engine performance simulation code, extractions and injections are investigated for a range of flows and for varied rear stage bleeding locations. Inter-stage bleeding is seen to unload the stage of extraction towards choke, while loading the subsequent stages, pushing them towards stall. Extracting after the last stage is shown to be appropriate for a wider range of flows: up to 15% of the compressor inlet flow. Injecting in this location at high flows pushes the closest stage towards stall. The same effect is observed in all the stages but to a lesser magnitude. Up to 17.5% injection seems allowable before compressor stalls; however, a more conservative estimate is expected with higher fidelity models. The study also shows an increase in performance with a rise in flow injection. Varying the design stage pressure ratio distribution brought about an improvement in the stall margin utilized, only for high extraction.


Author(s):  
Abdallah Bouam ◽  
Slimane Aissani ◽  
Rabah Kadi

The gas turbines are generally used for large scale power generation. The basic gas turbine cycle has low thermal efficiency, which decreases in the hard climatic conditions of operation, so the cycles with thermodynamic improvement is found to be necessary. Among several methods shown their success in increasing the performances, the steam injected gas turbine cycle (STIG) consists of introducing a high amount of steam at various points in the cycle. The main purpose of the present work is to improve the principal characteristics of gas turbine used under hard condition of temperature in Algerian Sahara by injecting steam in the combustion chamber. The suggested method has been studied and compared to a simple cycle. Efficiency, however, is held constant when the ambient temperature increases from ISO conditions to 50°C. Computer program has been developed for various gas turbine processes including the effects of ambient temperature, pressure ratio, injection parameters, standard temperature, and combustion chamber temperature with and without steam injection. Data from the performance testing of an industrial gas turbine, computer model, and theoretical study are used to check the validity of the proposed model. The comparison of the predicted results to the test data is in good agreement. Starting from the advantages, we recommend the use of this method in the industry of hydrocarbons. This study can be contributed for experimental tests.


Author(s):  
R. Bhargava ◽  
A. Peretto

In the present paper, a comprehensive methodology for the thermo-economic performance optimization of an intercooled reheat (ICRH) gas turbine with recuperation for cogenerative applications has been presented covering a wide range of power-to-heat ratio values achievable. To show relative changes in the thermo-economic performance for the recuperated ICRH gas turbine cycle, results for ICRH, recuperated Brayton and simple Brayton cycles are also included in the paper. For the three load cases investigated, the recuperated ICRH gas turbine cycle provides the highest values of electric efficiency and Energy Saving Index for the cogenerative systems requiring low thermal loads (high power-to-heat ratio) compared to the other cycles. Also, this study showed, in general, that the recuperated ICRH cycle permits wider power-to-heat ratio range compared to the other cycles and for different load cases examined, a beneficial thermodynamic characteristic for the cogeneration applications. Furthermore, this study clearly shows that implementation of the recuperated ICRH cycle in a cogeneration system will permit to design a gas turbine which has the high specific work capacity and high electric efficiency at low value of the overall cycle pressure ratio compared to the other cycles studied. Economic performance of the investigated gas turbine cycles have been found dependent on the power-to-heat ratio value and the selected cost structure (fuel cost, electric sale price, steam sale price etc.), the results for a selected cost structure in the study are discussed in this paper.


2020 ◽  
Vol 22 (2) ◽  
pp. 593-602 ◽  
Author(s):  
Andrey Rogalev ◽  
Vladimir Kindra ◽  
Alexey Zonov ◽  
Nikolay Rogalev ◽  
Levon Agamirov

AbstractThis study aims to present a method for precooling bleed flow by water injection in the E-MATIANT cycle and to estimate its impact on the overall efficiency. The design parameters of the cycle are set up on the basis of the component technologies of today's state-of-the-art gas turbines with a turbine inlet temperature between 1100 and 1700°C. Several schemes of the E-MATIANT cycle are considered: with one, two and three combustion chambers. The optimal pressure ratio ranges for the considered turbine inlet temperatures are identified and a comparison with existing evaluations is made. For the optimal initial parameters, cycle net efficiency varies from 42.0 to 49.8%. A significant influence of turbine stage cooling model on optimal thermodynamic parameters and cycle efficiency is established. The maximum cycle efficiency is 44.0% considering cooling losses. The performance penalty due to the oxygen production and carbon dioxide capture is 20–22%.


1982 ◽  
Vol 104 (2) ◽  
pp. 429-438 ◽  
Author(s):  
M. B. Cutrone ◽  
M. B. Hilt ◽  
A. Goyal ◽  
E. E. Ekstedt ◽  
J. Notardonato

The work described in this paper is part of the DOE/LeRC Advanced Conversion-Technology Project (ACT). The program is a multiple contract effort with funding provided by the Department of Energy, and technical program management provided by NASA LeRC. Combustion tests are in progress to evaluate the potential of seven advanced combustor concepts for achieving low NOx emissions for utility gas turbine engines without the use of water injection. Emphasis was on the development of the required combustor aerothermodynamic features for burning high nitrogen fuels. Testing was conducted over a wide range of operating conditions for a 12:1 pressure ratio heavy-duty gas turbine. Combustors were evaluated with distillate fuel, SRC-II coal-derived fuel, residual fuel, and blends. Test results indicate that low levels of NOx and fuel-bound nitrogen conversion can be achieved with rich-lean combustors for fuels with high fuel-bound nitrogen. In addition, ultra-low levels of NOx can be achieved with lean-lean combustors for fuels with low fuel-bound nitrogen.


Author(s):  
M. Zockel

A quasi-steady-state analysis is made of the performance of a gas-turbine working with intermittent, constant volume combustion. Variables considered include inlet temperature, compressor pressure ratio, scavenge ratio, combustion time, heat exchanger thermal ratio. Characteristics are computed over a full loading range. Computations are based on turbines having the following behavior: (a) constant turbine efficiency, (b) characteristics of a multistage axial turbine, and (c) characteristics of a single-stage radial turbine. The analysis indicates that the constant volume gas turbine has advantages in thermal efficiency, specific power and part load performance over constant pressure gas turbines operating at the same compressor pressure ratio and turbine inlet temperature. However, the addition of a heat exchanger shows less advantage when applied to a constant volume than to a constant pressure engine.


Author(s):  
J H Horlock

A graphical method of calculating the performance of gas turbine cycles, developed by Hawthorne and Davis (1), is adapted to determine the pressure ratio of a combined cycle gas turbine (CCGT) plant which will give maximum overall efficiency. The results of this approximate analysis show that the optimum pressure ratio is less than that for maximum efficiency in the higher level (gas turbine) cycle but greater than that for maximum specific work in that cycle. Introduction of reheat into the higher cycle increases the pressure ratio required for maximum overall efficiency.


Author(s):  
Mohand A. Ait-Ali

With or without turbine blade cooling, gas turbine cycles have consistently higher turbine inlet temperatures than steam turbine cycles. But this advantage is more than offset by the excessive compressor work induced by warm inlet temperatures, particularly during operation on hot summer days. Instead of seeking still higher turbine inlet temperatures by means of sophisticated blade cooling technology and high temperature-resistant blade materials, it is proposed to greatly increase the cycle net work and also improve thermal efficiency by decreasing the compressor work. This is obtained by using refrigerated inlet air and compressor intercooling to an extent which optimizes the refrigerated air inlet temperature and consequently the gas turbine compression ratio with respect to maximum specific net power. The cost effectiveness of this conceptual cycle, which also includes regeneration, has not been examined in this paper as it requires unusually high pressure ratio gas turbines and compressors, as well as high volumetric air flow rate and low temperature refrigeration equipment for which reliable cost data is not easily available.


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