The Evaporative Gas Turbine [EGT] Cycle

1997 ◽  
Author(s):  
J. H. Horlock
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Mass Flow ◽  
Power Output ◽  
Pressure Ratio ◽  
Temperature Drop ◽  
Optimum Pressure ◽  
Flow Through ◽  
Gas Turbine Exhaust ◽  
Gas Turbine Cycle

Humidification of the flow through a gas turbine has been proposed in a variety of forms. The STIG plant involves the generation of steam by the gas turbine exhaust in a heat recovery steam generator [HRSG], and its injection into or downstream of the combustion chamber. This increases the mass flow through the turbine and the power output from the plant, with a small increase in efficiency. In the evaporative gas turbine [or EGT] cycle, water is injected in the compressor discharge in a regenerative gas turbine cycle [a so-called CBTX plant-compressor [C], burner [B], turbine [T], heat exchanger [X]]; the air is evaporatively cooled before it enters the heat exchanger. While the addition of water increases the turbine mass flow and power output, there is also apparent benefit in reducing the temperature drop in the exhaust stack. In one variation of the basic EGT cycle, water is also added downstream of the evaporative aftercooler, even continuously in the heat exchanger. There are several other variations on the basic cycle [e.g. the cascaded humidified advanced turbine (CHAT)]. The present paper analyses the performance of the EGT cycle. The basic thermodynamics are first discussed, and related to the cycle analysis of a dry regenerative gas turbine plant. Subsequently some detailed calculations of EGT cycles are presented. The main purpose of the work is to seek the optimum pressure ratio in the EGT cycle for given constraints [e.g. fixed maximum to minimum temperature]. It is argued that this optimum has a relatively low value.

The Evaporative Gas Turbine [EGT] Cycle

1998 ◽  
Vol 120 (2) ◽  
pp. 336-343 ◽  
Author(s):  
J. H. Horlock
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Mass Flow ◽  
Power Output ◽  
Temperature Drop ◽  
Optimum Pressure ◽  
Turbine Plant ◽  
Flow Through ◽  
Gas Turbine Exhaust ◽  
Gas Turbine Cycle

Humidification of the flow through a gas turbine has been proposed in a variety of forms. The STIG plant involves the generation of steam by the gas turbine exhaust in a heat recovery steam generator (HRSG), and its injection into or downstream of the combustion chamber. This increases the mass flow through the turbine and the power output from the plant, with a small increase in efficiency. In the evaporative gas turbine (or EGT) cycle, water is injected in the compressor discharge in a regenerative gas turbine cycle (a so-called CBTX plant—compressor [C], burner [B], turbine [T], heat exchanger [X]); the air is evaporatively cooled before it enters the heat exchanger. While the addition of water increases the turbine mass flow and power output, there is also apparent benefit in reducing the temperature drop in the exhaust stack. In one variation of the basic EGT cycle, water is also added downstream of the evaporative aftercooler, even continuously in the heat exchanger. There are several other variations on the basic cycle (e.g., the cascaded humidified advanced turbine [CHAT]). The present paper analyzes the performance of the EGT cycle. The basic thermodynamics are first discussed, and related to the cycle analysis of a dry regenerative gas turbine plant. Subsequently some detailed calculations of EGT cycles are presented. The main purpose of the work is to seek the optimum pressure ration in the EGT cycle for given constraints (e.g., fixed maximum to minimum temperature). It is argued that this optimum has a relatively low value.

The Optimum Pressure Ratio for a Combined Cycle Gas Turbine Plant

1995 ◽  
Vol 209 (4) ◽  
pp. 259-264 ◽  
Author(s):  
J H Horlock
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Maximum Efficiency ◽  
Specific Work ◽  
Optimum Pressure ◽  
Turbine Plant ◽  
Gas Turbine Plant ◽  
Overall Efficiency ◽  
Gas Turbine Cycle

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.

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
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Water Injection ◽  
Compressed Air ◽  
Specific Work ◽  
Turbine Inlet ◽  
Higher Temperature ◽  
Gas Turbine Cycle

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.

A new analysis of recuperative gas turbine cycles

1998 ◽  
Vol 212 (4) ◽  
pp. 289-296 ◽  
Author(s):  
R Cai
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Optimum Pressure ◽  
Calculation Results ◽  
New Criterion ◽  
Gas Turbine Cycle ◽  
Cycle Efficiency ◽  
Analytical Expressions ◽  
Typical Calculation

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.

Performance improvements of the recuperated gas turbine cycle using absorption inlet cooling and evaporative aftercooling

2002 ◽  
Vol 216 (4) ◽  
pp. 295-306 ◽  
Author(s):  
A. M. Bassily
Keyword(s):  
Gas Turbine ◽  
Parametric Study ◽  
Cooling System ◽  
Pressure Ratio ◽  
Inlet Temperature ◽  
Temperature Ratio ◽  
Optimum Pressure ◽  
Performance Improvements ◽  
Gas Turbine Cycle ◽  
The Impact

An absorption inlet cooling system is introduced into the recuperated gas turbine cycle. The exhaust gases of the cycle are used to run the system. Five different layouts of the recuperated gas turbine cycle are presented. These include the effects of absorption inlet cooling, evaporative inlet cooling and evaporative cooling of compressor discharge (evaporative aftercooling), and the combined effect of absorption inlet cooling and evaporative aftercooling. A parametric study of the effect of pressure ratio, ambient temperature and relative humidity on the performance of all cycles is carried out. The results indicate that absorption inlet cooling could increase the efficiency of the recuperated cycle by up to 4 per cent, compared with 2.2 per cent for evaporative inlet cooling. Absorption inlet cooling with evaporative aftercooling could increase the optimum per efficiency of the recuperated cycle by up to 5 per cent and its maximum power by up to 65 per cent. Evaporative aftercooling reduces the impact of inlet cooling. Another parametric study of the effect of the turbine compressor inlet temperature ratio on the optimum pressure ratios indicated that cycles with evaporative aftercooling have higher optimum pressure ratios, which could be a function of the inlet temperature ratio and air temperature at the compressor outlet.

The Effect of Manufacturing Tolerances on the Performance of Gas Turbine Air System Metering Holes With Chamfered Inlets

2018 ◽  
Author(s):  
Polina Chernukha ◽  
Adrian Spencer ◽  
James A. Colwill
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Small Deviation ◽  
Pressure Ratio ◽  
Mean Flow ◽  
High Discharge ◽  
Large Pressure ◽  
Flow Through ◽  
Manufacturing Tolerances ◽  
The Mean

The current study represents an experimental and steady-state computational analysis of the mass flow through a single metering orifice with uniform and non-uniform chamfers. Chamfered holes have been used extensively in gas turbine air-systems for the ease of production and their (relatively high) discharge coefficient is insensitive to typical chamfer depth tolerances. This work extends the understanding of chamfer tolerances by investigating non-uniform chamfers due to angular misalignment of the chamfer tool relative to the hole. The range of the deviation angles between the axis of the tool and the axis of the metering orifice was 0–12°. The tests were performed in the pressure ratio range of 1.1...1.48, representing the range between idle and take-off operation points. A 3D CFD analysis of the tests using the Shear-Stress Transport (SST) k–ω model to simulate the mean flow field inside the metering orifice has also been completed. The results showed that at large pressure ratios, representative of the take-off operation point, the metering orifice with non-uniform chamfers showed reduction in mass flow delivery as high as 4%. A threshold in metering holes performance was detected for the tool inclination of 9.5°. At low pressure ratios, for conditions typically representative of idle operation point, a small deviation angle causes mass flow increase across the orifice.

Thermal and Economic Analysis of Gas Turbine Steam Injection Plant

2006 ◽  
Author(s):  
Sepehr Sanaye ◽  
Vahid Mahdikhani ◽  
Ziaeddin Khajeh Karimeddini ◽  
Gholamreza Sadri
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Power Output ◽  
Steam Injection ◽  
Nox Emissions ◽  
Gas Turbine Exhaust ◽  
Turbine Exhaust

Steam injection into gas turbine combustion chamber increases the power output and lowers the NOx emissions. Steam may be produced in a heat recovery steam generator (HRSG), using gas turbine exhaust gases. Steam which is usually injected with pressure of combustion chamber, increases the mass flow rate flowing through turbine and decreases the combustion temperature, hence, lowering the amount of NOx emissions. This power augmentation method is usually used for gas turbines with power outputs in range of 2–50 MW with one pressure level in HRSG. In this paper the optimum design parameters of the above mentioned system is obtained for the above range of gas turbine power output. For doing this task an objective function is introduced which contains the economic and thermal characteristics of the system. This objective function is minimized when gas turbine exhaust temperature, compressor pressure ratio, isentropic efficiency of compressor and turbine, fuel mass flow rate (natural gas), inlet air mass flow rate, and the amount of injected steam mass flow rate vary.

Leakage flow analysis in the gas turbine shroud gap

2019 ◽  
Vol 91 (8) ◽  
pp. 1077-1085 ◽  
Author(s):  
Filip Wasilczuk ◽  
Pawel Flaszynski ◽  
Piotr Kaczynski ◽  
Ryszard Szwaba ◽  
Piotr Doerffer ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Gas Turbine ◽  
Mass Flow ◽  
Labyrinth Seal ◽  
Leakage Flow ◽  
Original Design ◽  
Reference Case ◽  
Content Type ◽  
Flow Through ◽  
The Impact

Purpose The purpose of the study is to measure the mass flow in the flow through the labyrinth seal of the gas turbine and compare it to the results of numerical simulation. Moreover the capability of two turbulence models to reflect the phenomenon will be assessed. The studied case will later be used as a reference case for the new, original design of flow control method to limit the leakage flow through the labyrinth seal. Design/methodology/approach Experimental measurements were conducted, measuring the mass flow and the pressure in the model of the labyrinth seal. It was compared to the results of numerical simulation performed in ANSYS/Fluent commercial code for the same geometry. Findings The precise machining of parts was identified as crucial for obtaining correct results in the experiment. The model characteristics were documented, allowing for its future use as the reference case for testing the new labyrinth seal geometry. Experimentally validated numerical model of the flow in the labyrinth seal was developed. Research limitations/implications The research studies the basic case, future research on the case with a new labyrinth seal geometry is planned. Research is conducted on simplified case without rotation and the impact of the turbine main channel. Practical implications Importance of machining accuracy up to 0.01 mm was found to be important for measuring leakage in small gaps and decision making on the optimal configuration selection. Originality/value The research is an important step in the development of original modification of the labyrinth seal, resulting in leakage reduction, by serving as a reference case.

scholarly journals Methanol Dissociative Intercooling in Gas Turbines

1982 ◽  
Author(s):  
M. F. Bardon ◽  
J. A. C. Fortin
Keyword(s):  
Carbon Monoxide ◽  
Theoretical Analysis ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Unit Mass ◽  
Cycle Model ◽  
Optimum Pressure ◽  
Heating Value ◽  
Compressor Work

This paper examines the possibility of injecting methanol into the compressor of a gas turbine, then dissociating it to carbon monoxide and hydrogen so as to cool the air and reduce the work of compression, while simultaneously increasing the fuel’s heating value. A theoretical analysis shows that there is a net reduction in compressor work resulting from this dissociative intercooling effect. Furthermore, by means of a computer cycle model, the effects of dissociation on efficiency and work per unit mass of airflow are predicted for both regenerated and unregenerated gas turbines. The effect on optimum pressure ratio is examined and practical difficulties likely to be encountered with such a system are discussed.

Recuperators in Gas Turbine Systems

1998 ◽  
Author(s):  
Esa Utriainen ◽  
Bengt Sundén
Keyword(s):  
Research And Development ◽  
Gas Turbine ◽  
Cross Sections ◽  
Heat Exchangers ◽  
Power Plants ◽  
Pressure Ratio ◽  
Compact Heat Exchangers ◽  
Thermodynamic Cycles ◽  
Large Pressure ◽  
Gas Turbine Cycle

The application of recuperators in advanced thermodynamic cycles is growing due to stronger demands of low emissions of pollutants and the necessity of improving the cycle efficiency of power plants to reduce the fuel consumption. This paper covers applications and types of heat exchangers used in gas turbine units. The trends of research and development are brought up and the future need for research and development is discussed. Material aspects are covered to some extent. Attempts to achieve compact heat exchangers for these applications are also discussed. With the increasing pressure ratio in the gas turbine cycle, large pressure differences between the hot and cold sides exist. This has to be accounted for. The applicability of CFD (Computational Fluid Dynamics) is discussed and a CFD–approach is presented for a specific recuperator. This recuperator has narrow wavy ducts with complex cross-sections and the hydraulic diameter is so small that laminar flow prevails. The thermal-hydraulic performance is of major concern.

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