Influence of Working Fluid on Gas Turbine Cooling Modeling

2013 ◽  
Author(s):  
Majed Sammak ◽  
Marcus Thern ◽  
Magnus Genrup
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Gas Turbines ◽  
Specific Power ◽  
Working Fluid ◽  
Cooling Effectiveness ◽  
Fuel Gas ◽  
Turbine Cooling ◽  
Blade Cooling ◽  
Turbine Inlet

Cooling is essential in all modern high-temperature gas turbines. Turbine cooling is mainly a function of gas entry temperature, which plays the key role in overall gas turbine performance. High turbine entry temperatures can be achieved through appropriate selection of blade cooling method and blade material. The semi-closed oxy-fuel combustion combined cycle (SCOC-CC) operates at the same high entry gas temperature, hence blade cooling is necessary. The aim of this paper was to calculate the required turbine cooling in oxy-fuel gas turbines and compare it to the required turbine cooling in conventional gas turbines. The approach of the paper was to evaluate the thermodynamic and aerodynamic factors affecting turbine cooling with using the m*-model. The results presented in the paper concerned a single turbine stage at a reference diameter. The study showed greater cooling effectiveness in conventional gas turbines, but a greater total cooled area in oxy-fuel gas turbines. Consequently, the calculated total required cooling mass flow was close in the both single stage turbines. The cooling requirement and cooled area for a conventional and oxy-fuel twin-shaft gas turbine was also examined. The gas turbine was designed with five turbine stages. The analysis involved various turbine power and combustion outlet temperatures (COT). The results showed that the total required cooling mass flow was proportional to turbine power because of increasing gas turbine inlet mass flow. The required cooling mass flow was proportional to COT as the blade metal temperature is maintained at acceptable limit. The analysis revealed that required cooling for oxy-fuel gas turbines was higher than for conventional gas turbines at a specific power or specific COT. This is due to the greater cooled area in oxy-fuel gas turbines. The cooling effectiveness of conventional gas turbines was greater, which indicated higher required cooling. However, the difference in cooling effectiveness between conventional and oxy-fuel gas turbines was less in rear stages. The cooling mass flow as percentage of gas turbine inlet mass was slightly higher in conventional gas turbines than in oxy-fuel gas turbines. The required cooling per square meter of cooled area was used as a parameter to compare the required cooling for oxy-fuel and conventional gas turbines. The study showed that the required cooling per cooled area was close in both studied turbines.

The Heat Transfer Performance of Porous Gas Turbine Blades

1968 ◽  
Vol 72 (696) ◽  
pp. 1087-1094 ◽  
Author(s):  
F. J. Bayley ◽  
A. B. Turner
Keyword(s):  
Gas Turbine ◽  
Turbine Blades ◽  
Engine Performance ◽  
Operating Conditions ◽  
Maximum Temperature ◽  
Specific Power ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Turbine Inlet ◽  
Compression And Expansion

It is well known that the performance of the practical gas turbine cycle, in which compression and expansion are non-isentropic, is critically dependent upon the maximum temperature of the working fluid. In engines in which shaft-power is produced the thermal efficiency and the specific power output rise steadily as the turbine inlet temperature is increased. In jet engines, in which the gas turbine has so far found its greatest success, similar advantages of high temperature operation accrue, more particularly as aircraft speeds increase to utilise the higher resultant jet velocities. Even in high by-pass ratio engines, designed specifically to reduce jet efflux velocities for application to lower speed aircraft, overall engine performance responds very favourably to increased turbine inlet temperatures, in which, moreover, these more severe operating conditions apply continuously during flight, and not only at maximum power as with more conventional cycles.

The Effect of Alternative Turbine Cooling Schemes on the Performance of Utility Gas Turbine Powerplants

1982 ◽  
Author(s):  
Arthur Cohn ◽  
Mark Waters
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Power Plants ◽  
Heat Rate ◽  
Combined Cycle ◽  
Specific Power ◽  
Cooling Effectiveness ◽  
Turbine Cooling ◽  
The Impact ◽  
Systems Studies

It is important that the requirements and cycle penalties related to the cooling of high temperature turbines be thoroughly understood and accurately factored into cycle analyses and power plant systems studies. Various methods used for the cooling of high temperature gas turbines are considered and cooling effectiveness curves established for each. These methods include convection, film and transpiration cooling using compressor bleed and/or discharge air. In addition, the effects of chilling the compressor discharge cooling gas are considered. Performance is developed to demonstrate the impact of the turbine cooling schemes on the heat rate and specific power of Combined–Cycle power plants.

scholarly journals Conceptual Mean-Line Design of Single and Twin-Shaft Oxy-Fuel Gas Turbine in a Semiclosed Oxy-Fuel Combustion Combined Cycle

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Majed Sammak ◽  
Egill Thorbergsson ◽  
Tomas Grönstedt ◽  
Magnus Genrup
Keyword(s):  
Mach Number ◽  
Gas Turbine ◽  
Mass Flow ◽  
Rotational Speed ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Fuel Gas ◽  
Power Turbine ◽  
Exit Mach Number ◽  
Line Design

The aim of this study was to compare single- and twin-shaft oxy-fuel gas turbines in a semiclosed oxy-fuel combustion combined cycle (SCOC–CC). This paper discussed the turbomachinery preliminary mean-line design of oxy-fuel compressor and turbine. The conceptual turbine design was performed using the axial through-flow code luax-t, developed at Lund University. A tool for conceptual design of axial compressors developed at Chalmers University was used for the design of the compressor. The modeled SCOC–CC gave a net electrical efficiency of 46% and a net power of 106 MW. The production of 95% pure oxygen and the compression of CO2 reduced the gross efficiency of the SCOC–CC by 10 and 2 percentage points, respectively. The designed oxy-fuel gas turbine had a power of 86 MW. The rotational speed of the single-shaft gas turbine was set to 5200 rpm. The designed turbine had four stages, while the compressor had 18 stages. The turbine exit Mach number was calculated to be 0.6 and the calculated value of AN2 was 40 · 106 rpm2m2. The total calculated cooling mass flow was 25% of the compressor mass flow, or 47 kg/s. The relative tip Mach number of the compressor at the first rotor stage was 1.15. The rotational speed of the twin-shaft gas generator was set to 7200 rpm, while that of the power turbine was set to 4800 rpm. A twin-shaft turbine was designed with five turbine stages to maintain the exit Mach number around 0.5. The twin-shaft turbine required a lower exit Mach number to maintain reasonable diffuser performance. The compressor turbine was designed with two stages while the power turbine had three stages. The study showed that a four-stage twin-shaft turbine produced a high exit Mach number. The calculated value of AN2 was 38 · 106 rpm2m2. The total calculated cooling mass flow was 23% of the compressor mass flow, or 44 kg/s. The compressor was designed with 14 stages. The preliminary design parameters of the turbine and compressor were within established industrial ranges. From the results of this study, it was concluded that both single- and twin-shaft oxy-fuel gas turbines have advantages. The choice of a twin-shaft gas turbine can be motivated by the smaller compressor size and the advantage of greater flexibility in operation, mainly in the off-design mode. However, the advantages of a twin-shaft design must be weighed against the inherent simplicity and low cost of the simple single-shaft design.

Redesign of the TG20 Heavy-Duty Gas Turbine to Increase Turbine Inlet Temperature and Global Efficiency

2020 ◽  
Author(s):  
Mirko Baratta ◽  
Francesco Cardile ◽  
Daniela Anna Misul ◽  
Nicola Rosafio ◽  
Simone Salvadori ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Coolant Fluid ◽  
Specific Power ◽  
Inlet Temperature ◽  
Heavy Duty ◽  
Turbine Inlet Temperature ◽  
Rotating Blade ◽  
Turbine Inlet ◽  
Heavy Duty Gas Turbine

Abstract The even more stringent limitations set by the European Commission on pollutant emissions are forcing gas turbine manufacturers towards the redesign of the most important components to increase efficiency and specific power. Current trends in gas turbine design include an increased attention to the design of cooling systems and enhanced best practices for the study of components interaction. At the same time, the recent crisis suffered by the oil and gas industry reduced the interest in brand new gas turbines, thus increasing the service market. Therefore, original equipment manufacturers would rather propose the replacement of specific components within the gas turbine plant during its maintenance with compatible elements that are likely to guarantee increased performance and longer residual lifetime at a more desirable nominal working point. In the present activity the cooling system of the TG20 heavy-duty gas turbine has been redesigned to increase the turbine inlet temperature while contemporaneously reducing the total amount of coolant mass-flow. Specifically, the cooling scheme of the rotating blade of the first turbine row has been reviewed at the Department of Energy (DENERG) of Politecnico di Torino in cooperation with EthosEnergy Italia S.p.a.. The paper presents a new design, which, starting from the original solution featuring fifteen smooth pipes, adopts an improved geometry characterized by the presence of turbulators. The activity has been carried out using Computational Fluid Dynamics (CFD) for the coolant/blade interaction and one-dimensional models developed at EthosEnergy for the redistribution of the cooling flows in the cavities. The mutual effects between the coolant fluid and the blade are analyzed using a Conjugate Heat Transfer (CHT) approach with Star-CCM+. The validation of the computational approach has been performed exploiting the experimental data available for the NASA C3X test case. The TG20 rotating blade of the first turbine row has been analyzed considering the two different coolant configurations. The impact of the main flow on the thermal field has initially been included by imposing a temperature field on the blade surface. The latter field has in turn been obtained by means of a separate computation for the solid only. Full CHT simulations has hence been performed, thus quantifying the accuracy of the proposed approach. The obtained results are discussed in terms of thermo-fluid-dynamic effects.

scholarly journals Optimum Power Boosting of Gas Turbine Cycles With Refrigerated Inlet Air and Compressor Intercooling

1996 ◽  
Author(s):  
Mohand A. Ait-Ali
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Inlet Temperature ◽  
Turbine Blade Cooling ◽  
High Pressure Ratio ◽  
Blade Cooling ◽  
Air Inlet ◽  
Turbine Inlet ◽  
Compressor Work

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.

Three Reactors Chemical Looping Combustion for High Efficiency Electricity Generation With CO2 Capture From Natural Gas

2006 ◽  
Author(s):  
Giovanni Lozza ◽  
Paolo Chiesa ◽  
Matteo Romano ◽  
Paolo Savoldelli
Keyword(s):  
Natural Gas ◽  
Metal Oxide ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Specific Power ◽  
Working Fluid ◽  
Chemical Looping Combustion ◽  
Chemical Looping ◽  
Water Separation ◽  
Oxidation Reactor

Chemical-Looping Combustion (CLC) is a process where fuel oxidation is accomplished by the oxygen carried by a metal oxide, circulating across two reactors: a reduction reactor (reducing the metal oxide by oxidizing the natural gas fuel) and an oxidation reactor (re-oxidizing the metal by reacting with air, a strongly exothermic reaction). The system produces: (i) a stream of oxidation products (CO2 and H2O), ready for carbon sequestration after water separation and CO2 liquefaction; (ii) a stream of hot air (deprived of some oxygen) used as working fluid of a gas turbine cycle. Due to the moderate temperature (∼850°C) of this stream, sensibly lower than those adopted in commercial gas turbines, the combined cycle arranged around this concept suffers from poor conversion efficiency and, therefore, economics. In the present paper, the basic CLC arrangement is modified by inserting a third reactor in the loop. This reactor, by exploiting an intermediate oxidation state of the circulating metal, produces H2 used as decarbonized fuel to raise the temperature of the air coming from the oxidation reactor, up to the highest value allowed by the modern gas turbine technology (∼1350°C), thus achieving elevated efficiency and specific power output. This paper is aimed to assess the potential of power cycles based on the three reactors (CLC3) arrangement. More specifically, we will discuss the plant configuration, the process optimization and the performance prediction. Results show that the CLC3 system is very promising: the net LHV efficiency of the best configuration exceeds 51%, an outstanding figure for a natural gas power cycle producing liquid, disposal-ready CO2 and negligible NOx emissions. Commercial gas turbines can be easily adapted to operate in the specific conditions of the CLC3 arrangement which, apart from the reactors system, does not require the development of novel technologies and/or high-risk components. The paper also reports a final comparison with a rival technology based on natural gas partial oxidation, water-gas shift reaction and CO2 separation by MDEA absorption. This work has been performed within the research on the Italian Electrical System “Ricerca di Sistema”, Ministerial Decrees of January 26 – 2000, and April 17 – 2001.

Investigation of Cooling Effectiveness of Gas Turbine Inlet Fogging Location Relative to the Silencer

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Jobaidur R. Khan ◽  
Ting Wang ◽  
Mustapha Chaker
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Cost Effective ◽  
Water Droplets ◽  
Cooling Effectiveness ◽  
Droplet Dynamics ◽  
Erosion Risk ◽  
Percentage Points ◽  
Turbine Inlet ◽  
Before And After

The output and efficiency of gas turbines are reduced significantly during the summer, especially in areas where the daytime temperature reaches as high as 50°C. Gas turbine inlet fogging and overspray has been considered a simple and cost-effective method to increase the power output. One of the most important issues related to inlet fogging is to determine the most effective location of the fogging device by determining (a) how many water droplets actually evaporate effectively to cool down the inlet air instead of colliding on the wall or coalescing and draining out (i.e., fogging efficiency), and (b) quantifying the amount of nonevaporated droplets that may reach the compressor bellmouth to ascertain the erosion risk for compressor airfoils if wet compression is to be avoided. When the silencer is installed, there is an additional consideration for placing the fogging device upstream or downstream of the silencer baffles. Placing arbitrarily the device upstream of the silencer can cause the silencer to intercept water droplets on the silencer baffles and lose cooling effectiveness. This paper employs computational fluid dynamics (CFD) to investigate the water droplet transport and cooling effectiveness with different spray locations such as before and after the silencer baffles. Analysis on the droplet history (trajectory and size) is employed to interpret the mechanism of droplet dynamics under influence of acceleration, diffusion, and body forces when the flow passes through the baffles and duct bent. The results show that, for the configuration of the investigated duct, installing the fogging system upstream of the silencer is about 3 percentage points better in evaporation effectiveness than placing it downstream of the silencer, irrespective of whether the silencer consists of a single row of baffles or two rows of staggered baffles. The evaporation effectiveness of the staggered silencer is about 0.8 percentage points higher than the single silencer. The pressure drop of the staggered silencer is 6.5% higher than the single silencer.

Investigation of Cooling Effectiveness of Gas Turbine Inlet Fogging Location Relative to the Silencer

2011 ◽  
Author(s):  
Jobaidur R. Khan ◽  
Ting Wang ◽  
Mustapha Chaker
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Cost Effective ◽  
Water Droplets ◽  
Cooling Effectiveness ◽  
Droplet Dynamics ◽  
Erosion Risk ◽  
Percentage Points ◽  
Turbine Inlet ◽  
Before And After

The output and efficiency of gas turbines are reduced significantly during the summer, especially in areas where the daytime temperature reaches as high as 50°C. Gas turbine inlet fogging and overspray has been considered a simple and cost-effective method to increase the power output. One of the most important issues related to inlet fogging is to determine the most effective location of the fogging device by determining (a) how many water droplets actually evaporate effectively to cool down the inlet air instead of colliding on the wall or coalescing and draining out (i.e. fogging efficiency), and (b) quantifying the amount of non-evaporated droplets that may reach the compressor bellmouth to ascertain the erosion risk for compressor airfoils if wet compression is to be avoided. When the silencer is installed, there is an additional consideration for placing the fogging device upstream or downstream of the silencer baffles. Placing arbitrarily the device upstream of the silencer can cause the silencer to intercept water droplets on the silencer baffles and lose cooling effectiveness. This paper employs computational fluid dynamics (CFD) to investigate the water droplet transport and cooling effectiveness with different spray locations such as before and after the silencer baffles. Analysis on the droplet history (trajectory and size) is employed to interpret the mechanism of droplet dynamics under influence of acceleration, diffusion, and body forces when the flow passes through the baffles and duct bent. The results show that, for the configuration of the investigated duct, installing the fogging system upstream of the silencer is about 3 percentage points better in evaporation effectiveness than placing it downstream of the silencer, irrespective of whether the silencer consists of a single row of baffles or two rows of staggered baffles. The evaporation effectiveness of the staggered silencer is about 0.8 percentage points higher than the single silencer. The pressure drop of the staggered silencer is 6.5% higher than the single silencer.

Optimization of Organic Rankine Cycles for Off-Shore Applications

2013 ◽  
Author(s):  
Leonardo Pierobon ◽  
Ulrik Larsen ◽  
Tuong Van Nguyen ◽  
Fredrik Haglind
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Optimization Procedure ◽  
Working Fluid ◽  
Maximum Pressure ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
Turbine Inlet ◽  
Organic Rankine Cycles

In off-shore oil and gas platform efficiency, the reliability and fuel flexibility are the major concerns when selecting the gas turbine to support the electrical and mechanical demand on the platform. In order to fulfill these requirements, turbine inlet temperature and pressure ratio are not increased up to the optimal values and one or more redundant gas turbines may be employed. With increasing incentives for reducing the CO2 emissions off-shore, improving the thermal efficiency has become a focus area. Due to the peculiar low turbine outlet temperature and due to space and weight constraints, a steam bottoming cycle is not a convenient solution. On the contrary, organic Rankine cycles (ORCs) present the benefits of high simplicity and compactness. Furthermore, the working fluid can be selected considering the temperature profile at which the heat is supplied; hence the heat transfer process and the thermal efficiency of the cycle can be maximized. This paper is aimed at finding the most optimal ORC tailored for off-shore applications using an optimization procedure based on the genetic algorithm. Numerous working fluids are screened through, considering mainly thermal efficiency, but also other characteristics of the fluids, e.g. stability, environmental and human health impacts, and safety issues. Both supercritical and subcritical ORCs are included in the analysis. The optimization procedure is first applied to a conservative ORC where the maximum pressure is limited to 20 bar. Subsequently the optimal working fluid is identified by removing the restriction on the maximum pressure. Different limits on hazards and global warming potential (GWP) are also set. The study is focused on the SGT-500 gas turbine installed on the Draugen platform in the Norwegian Sea. The simulations suggest that, when a high hazard is accepted, cyclohexane is the best solution. With a turbine inlet pressure limit of 20 bar, the combined gas turbine-ORC system presents an efficiency of 43.7%, corresponding to an improvement of 11.9%-points with respect to the gas turbine efficiency. With no upper pressure boundary, cyclohexane at 55.5 bar is the preferable working fluid with a combined thermal efficiency of 44.3%. The supercritical CO2 cycle with a maximum pressure of 192.9 bar is found to be the best alternative if an extremely low hazard is required.

scholarly journals Research on the influence of fuel gas on energy characteristics of a gas turbine

2019 ◽  
Vol 124 ◽  
pp. 05063 ◽  
Author(s):  
G.E. Marin ◽  
B.M. Osipov ◽  
D.I. Mendeleev
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Thermodynamic Cycle ◽  
Working Fluid ◽  
Fluid Composition ◽  
Fuel Gas ◽  
Turbine Engine ◽  
Equipment Operation ◽  
Turbine Efficiency ◽  
The Impact

The purpose of this paper is to study and analyze the gas turbine engine and the thermodynamic cycle of a gas turbine. The article describes the processes of influence of the working fluid composition on the parameters of the main energy gas turbines, depending on the composition of the fuel gas. The calculations of the thermal scheme of a gas turbine, which were made using mathematical modeling, are given. As a result of research on the operation of the GE PG1111 6FA gas turbine installation with various gas compositions, it was established that when the gas turbine is operating on different fuel gases, the engine efficiency changes. The gas turbine efficiency indicators were determined for various operating parameters and fuel composition. The impact of fuel components on the equipment operation is revealed.

Sign in / Sign up

Export Citation Format

Share Document