A Modified, High-Efficiency, Recuperated Gas Turbine Cycle

1988 ◽  
Vol 110 (2) ◽  
pp. 233-242 ◽  
Author(s):  
M. A. El-Masri
Keyword(s):  
Gas Turbine ◽  
High Efficiency ◽  
Water Flow Rate ◽  
Component Technology ◽  
Pure Substance ◽  
Working Fluid ◽  
Recovery Processes ◽  
Dead State ◽  
Percentage Points ◽  
Wide Range

The thermal efficiency of an intercooled/recuperated cycle may be increased by: (a) evaporatively aftercooling the compressor discharge; and (b) injecting and evaporating an additional amount of water in the recuperator. Comparative computations of such a modified cycle and intercooled/recuperated cycles carried out over a wide range of pressure ratios and turbine inlet temperatures and at two different levels of component technologies show an advantage of over five percentage points in efficiency for the modified cycle. About 60 percent of this improvement results from modification (a) and 40 percent from modification (b). The modified intercooled/recuperated cycle is compared with nonintercooled steam-injected gas turbine systems at each component technology level. The present cycle is found to be superior by about 2.75 percentage points in efficiency and to require a substantially smaller water flow rate. To assist in interpreting those differences, the method of available-work analysis is introduced and applied. This is identical to exergy analysis for systems with a pure-substance working fluid, but differs from the latter for systems using a mixture of pure substances insofar as the thermodynamic dead state is defined for the chemical and phase composition realized at the exhaust conditions of practical engineering devices and systems. This analysis is applied to the heat-recovery processes in each of the three systems considered. It shows that the substantial, fundamental available-work loss incurred by mixing steam and gases in the steam-injected system is the main reason for the superior efficiency of the precent cycle.

scholarly journals Development of the PGT 25 High Efficiency Gas Turbine: Part 2 — Aerodynamic Design and Performance

1984 ◽  
Author(s):  
E. Benvenuti ◽  
B. Innocenti ◽  
R. Modi
Keyword(s):  
Gas Turbine ◽  
High Efficiency ◽  
Performance Testing ◽  
Operating Conditions ◽  
Aerodynamic Design ◽  
Direct Drive ◽  
Gas Generator ◽  
Full Load ◽  
Wide Range ◽  
Overall Performance

This paper outlines parameter selection criteria and major procedures used in the PGT 25 gas turbine power spool aerodynamic design; significant results of the shop full-load tests are also illustrated with reference to both overall performance and internal flow-field measurements. A major aero-design objective was established as that of achieving the highest overall performance levels possible with the matching to latest generation aero-derivative gas generators; therefore, high efficiencies were set as a target both for the design point and for a wide range of operating conditions, to optimize the turbine’s uses in mechanical drive applications. Furthermore, the design was developed to reach the performance targets in conjunction with the availability of a nominal shaft speed optimized for the direct drive of pipeline booster centrifugal compressors. The results of the full-load performance testing of the first unit, equipped with a General Electric LM 2500/30 gas generator, showed full attainment of the design objectives; a maximum overall thermal efficiency exceeding 37% at nominal rating and a wide operating flexibility with regard to both efficiency and power were demonstrated.

scholarly journals High Efficiency-Coal and Gas (HE-C&G): An Advanced Hybrid Power Plant Concept With Sequential Combustion Gas Turbines GT24/GT26

1997 ◽  
Author(s):  
Mircea Fetescu
Keyword(s):  
Power Plant ◽  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Combustion Gas ◽  
Hybrid Power ◽  
Wide Range ◽  
Hybrid Power Plant ◽  
Very High

The High Efficiency-Coal and Gas (HE-C&G) is a hybrid power plant concept integrating Conventional Steam Power Plants (CSPP) and gas turbine / combined cycle plants. The gas turbine exhaust gas energy is recovered in the HRSG providing partial condensate and feedwater preheating and generating steam corresponding to the main boiler live steam conditions (second steam source for the ST). The concept, exhibiting very high design flexibility, integrates the high performance Sequential Combustion gas turbines GT24/GT26 technology into a wide range of existing or new CSPP. Although HE-C&G refers to coal as the most abundant fossil fuel resource, oil or natural gas fired steam plants could be also designed or converted following the same principle. The HE-C&G provides very high marginal efficiencies on natural gas, up to and above 60%, very high operating and dispatching flexibility and on-line optimization of fuel and O&M costs at low capital investment. This paper emphasizes the operating flexibility and resulting benefits, recommending the HE-C&G as one of the most profitable options for generating power especially for conversion of existing CSPP with gas turbines.

Flameholding Tendencies of Natural Gas and Hydrogen Flames at Gas Turbine Premixer Conditions

2014 ◽  
Author(s):  
Elliot Sullivan-Lewis ◽  
Vincent McDonell
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
High Reliability ◽  
Elevated Pressure ◽  
Inlet Temperature ◽  
Increased Risk ◽  
Wide Range ◽  
Lean Premixed

Ground based gas turbines are responsible for generating a significant amount of electric power as well as providing mechanical power for a variety of applications. This is due to their high efficiency, high power density, high reliability, and ability to operate on a wide range of fuels. Due to increasingly stringent air quality requirements, stationary power gas turbines have moved to lean-premixed operation. Lean-premixed operation maintains low combustion temperatures for a given turbine inlet temperature, resulting in low NOx emissions while minimizing emissions of CO and hydrocarbons. In addition, to increase overall cycle efficiency, engines are being operated at higher pressure ratios and/or higher combustor inlet temperatures. Increasing combustor inlet temperatures and pressures in combination with lean-premixed operation leads to increased reactivity of the fuel/air mixture, leading to increased risk of potentially damaging flashback. Curtailing flashback on engines operated on hydrocarbon fuels requires care in design of the premixer. Curtailing flashback becomes more challenging when fuels with reactive components such as hydrogen are considered. Such fuels are gaining interest because they can be generated from both conventional and renewable sources and can be blended with natural gas as a means for storage of renewably generated hydrogen. The two main approaches for coping with flashback are either to design a combustor that is resistant to flashback, or to design one that will not anchor a flame if a flashback occurs. An experiment was constructed to determine the flameholding tendencies of various fuels on typical features found in premixer passage ways (spokes, steps, etc.) at conditions representative of a gas turbine premixer passage way. In the present work tests were conducted for natural gas and hydrogen between 3 and 9 atm, between 530 K and 650K, and free stream velocities from 40 to 100 m/s. Features considered in the present study include a spoke in the center of the channel and a step at the wall. The results are used in conjunction with existing blowoff correlations to evaluate flameholding propensity of these physical features over the range of conditions studied. The results illustrate that correlations that collapse data obtained at atmospheric pressure do not capture trends observed for spoke and wall step features at elevated pressure conditions. Also, a notable fuel compositional effect is observed.

scholarly journals Thermodynamics and Performance Projections for Intercooled/Reheat/Recuperated Gas Turbine Systems

1987 ◽  
Author(s):  
Maher A. El-Masri
Keyword(s):  
Gas Turbine ◽  
High Performance ◽  
High Efficiency ◽  
Pure Water ◽  
Water Injection ◽  
Component Technology ◽  
Specific Power ◽  
Combined Cycles ◽  
And Performance ◽  
Marine Applications

Intercooled/Recuperated gas turbine systems provide high-efficiency and power density for naval propulsion. Current aero-derivative systems are capable of about 43% thermal efficiency in this configuration. With continued progress in gas-turbine materials and cooling technology, the possibility of further improving system performance by incorporation of gas-turbine reheat arises. A preliminary scan of this class of cycles is presented and compared with non-reheat intercooled/recuperated cycles at two levels of component technology. For conservative component technology, the reheat is found to provide very modest performance advantages. With advanced components and ceramic thermal barrier coatings, the reheat is found to offer potential for specific power improvements of up to 33% and for modest efficiency gains, on the order of one percentage point, while enabling turbine inlet temperatures well below those for the most efficient non-reheat cycles. The high-performance reheat systems, however, require reheat-combustor inlet temperatures beyond current practice. The use of water-injection in the intercooler, together with an aftercooler and a water-injected evaporative-recuperator is found to produce very large gains in efficiency as well as specific power. This modification may be feasible for land-based systems, where it can compete favourably with combined cycles. Despite the difficulty of obtaining pure water for a shipboard propulsion system, those large gains may justify further studies of this system and of means to provide its water supply in marine applications.

Computational Fluid Dynamics of a Radial Compressor Operating With Supercritical CO2

2012 ◽  
Author(s):  
Rene Pecnik ◽  
Enrico Rinaldi ◽  
Piero Colonna
Keyword(s):  
Critical Point ◽  
Gas Turbine ◽  
Supercritical Co2 ◽  
High Speed ◽  
Power Plants ◽  
Compressible Flows ◽  
High Efficiency ◽  
Fluid Dynamic ◽  
Working Fluid ◽  
Maximum Pressure

The merit of using supercritical CO2 (scCO2) as the working fluid of a closed Brayton cycle gas turbine is now widely recognized, and the development of this technology is now actively pursued. scCO2 gas turbine power plants are an attractive option for solar, geothermal and nuclear energy conversion. Among the challenges which must be overcome in order to successfully bring the technology to the market, the efficiency of the compressor and turbine operating with the supercritical fluid should be increased as much as possible. High efficiency can be reached by means of sophisticated aerodynamic design, which, compared to other overall efficiency improvements, like cycle maximum pressure and temperature increase, or increase of recuperator effectiveness, does not require an increase in equipment cost, but only an additional effort in research and development. This paper reports a three-dimensional CFD study of a high-speed centrifugal compressor operating with CO2 in the thermodynamic region slightly above the vapor-liquid critical point. The investigated geometry is the compressor impeller tested in the Sandia scCO2 compression loop facility [1]. The fluid dynamic simulations are performed with a fully implicit parallel Reynolds-averaged Navier-Stokes code based on a finite volume formulation on arbitrary polyhedral mesh elements. The CFD code has been validated on test cases which are relevant for this study, see Ref. [2,3]. In order to account for the strongly nonlinear variation of the thermophysical properties of supercritical CO2, the CFD code is coupled with an extensive library for the computation of properties of fluids and mixtures [4]. Among the available models, the one based on reference equations of state for CO2 [5,6] has been selected, as implemented in one of the sub-libraries [7]. A specialized look-up table approach and a meshing technique suited for turbomachinery geometries are also among the novelties introduced in the developed methodology. A detailed evaluation of the CFD results highlights the challenges of numerical studies aimed at the simulation of technically relevant compressible flows occurring close to the liquid-vapor critical point. The data of the obtained flow field are used for a comparison with experiments performed at the Sandia scCO2 compression-loop facility.

Oxy-Fuel Gas Turbine, Gas Generator and Reheat Combustor Technology Development and Demonstration

2010 ◽  
Author(s):  
Roger Anderson ◽  
Fermin Viteri ◽  
Rebecca Hollis ◽  
Ashley Keating ◽  
Jonathan Shipper ◽  
...  
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Clean Energy ◽  
Test Facility ◽  
Working Fluid ◽  
Capital Costs ◽  
2Nd Generation ◽  
Wide Range ◽  
And Performance

Future fossil-fueled power generation systems will require carbon capture and sequestration to comply with government green house gas regulations. The three prime candidate technologies that capture carbon dioxide (CO2) are pre-combustion, post-combustion and oxy-fuel combustion techniques. Clean Energy Systems, Inc. (CES) has recently demonstrated oxy-fuel technology applicable to gas turbines, gas generators, and reheat combustors at their 50MWth research test facility located near Bakersfield, California. CES, in conjunction with Siemens Energy, Inc. and Florida Turbine Technologies, Inc. (FTT) have been working to develop and demonstrate turbomachinery systems that accommodate the inherent characteristics of oxy-fuel (O-F) working fluids. The team adopted an aggressive, but economical development approach to advance turbine technology towards early product realization; goals include incremental advances in power plant output and efficiency while minimizing capital costs and cost of electricity [1]. Proof-of-concept testing was completed via a 20MWth oxy-fuel combustor at CES’s Kimberlina prototype power plant. Operability and performance limits were explored by burning a variety of fuels, including natural gas and (simulated) synthesis gas, over a wide range of conditions to generate a steam/CO2 working fluid that was used to drive a turbo-generator. Successful demonstration led to the development of first generation zero-emission power plants (ZEPP). Fabrication and preliminary testing of 1st generation ZEPP equipment has been completed at Kimberlina power plant (KPP) including two main system components, a large combustor (170MWth) and a modified aeroderivative turbine (GE J79 turbine). Also, a reheat combustion system is being designed to improve plant efficiency. This will incorporate the combustion cans from the J79 engine, modified to accept the system’s steam/CO2 working fluid. A single-can reheat combustor has been designed and tested to verify the viability and performance of an O-F reheater can. After several successful tests of the 1st generation equipment, development started on 2nd generation power plant systems. In this program, a Siemens SGT-900 gas turbine engine will be modified and utilized in a 200MWe power plant. Like the 1st generation system, the expander section of the engine will be used as an advanced intermediate pressure turbine and the can-annular combustor will be modified into a O-F reheat combustor. Design studies are being performed to define the modifications necessary to adapt the hardware to the thermal and structural demands of a steam/CO2 drive gas including testing to characterize the materials behavior when exposed to the deleterious working environment. The results and challenges of 1st and 2nd generation oxy-fuel power plant system development are presented.

scholarly journals New Mobile Gas Turbine with a Wide Range of Applications

2018 ◽  
Vol 140 (03) ◽  
pp. S54-S55
Author(s):  
Uwe Schütz
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Large Power ◽  
Power Stations ◽  
Wide Range ◽  
Term Basis

This article describes features and advantages of new mobile gas turbine with a wide range of applications. The market for mobile gas turbines is continuously growing. Mobile units are also an ideal choice when it comes to making large power capacities available on a short-term basis, for example, for major events, prolonged downtimes at other power stations, or power-intensive applications such as mining or shale gas extraction. If the electricity requirements exceed the level that can normally be demanded of a mobile application, an SGT-A45 installation can be modified to form a combined-cycle power plant to further improve its efficiency. In remote locations, this can be achieved using an Organic Rankine Cycle (ORC), to eliminate the need for water and water treatment systems, and to optimize energy recovery from the SGT-A45 off-gas stream at a relatively low temperature. The use of a direct heat exchanger, in which the ORC working fluid is evaporated by the off-gas stream from the gas turbine, can boost the system’s output capacity by more than 20 percent.

scholarly journals Analysis of the compressorless combined cycle gas turbine unit performance efficiency in district heating systems

2020 ◽  
Vol 209 ◽  
pp. 03008
Author(s):  
Yuriy Borisov ◽  
Nikolay Fominykh ◽  
Eldar Ramazanov ◽  
Oleg Popel
Keyword(s):  
Gas Turbine ◽  
District Heating ◽  
Combined Cycle ◽  
Maximum Power ◽  
Pure Oxygen ◽  
Working Fluid ◽  
Operating Modes ◽  
Central Russia ◽  
Wide Range ◽  
Oxygen Fuel

Nowadays, thermodynamic cycles are actively studied, in which pure oxygen and fuel are fed into a combustion chamber, and a temperature of a working fluid is regulated by the supply of carbon dioxide and/or water vapor. These cycles are called “oxygen-fuel”. They allow easy to separate CO2, resulting from a fuel combustion, from the working fluid and remove it from the cycle in its pure form. In addition, it has already been shown that an efficiency of electric power generation of such cycles is approaching the best known technologies. However, the efficiency of cogeneration of electricity and heat is more important for many energy systems, especially for Russian, in comparison with the efficiency of electricity generation. The main goal of the study was to analyze the thermal efficiency for cogeneration of electricity and heat of one of the options for the implementation of oxygen-fuel cycles - compressorless combined cycle gas turbine (CCGT) units. A mathematical model of the compressorless CCGT units was developed, which allows to study the thermal performance in a wide range of operating modes. It is conventionally accepted that the system requires a maximum power for power supply of 300 MW, and a maximum power for heat supply of 600 MW. It is assumed that 300 MW of electricity is constantly supplied to the network. In addition, the heat load is provided according to the standard schedule depending on the ambient temperature, and at the same time an averaged data on the temperature of atmospheric air for central Russia over a tenyear period is accepted. The comparison is made with a steam turbine CHP plant and a CCGTCHP plant. The results of the comparison showed a significant advantage of the compressorless CCGT unit.

scholarly journals Comparative analysis of the Allam cycle and the cycle of compressorless combined cycle gas turbine unit

2020 ◽  
Vol 209 ◽  
pp. 03023
Author(s):  
Mikhail Sinkevich ◽  
Anatoliy Kosoy ◽  
Oleg Popel
Keyword(s):  
Comparative Analysis ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Power Plants ◽  
Thermal Power ◽  
District Heating ◽  
Combined Cycle ◽  
Working Fluid ◽  
District Heating System ◽  
Wide Range

Nowadays, alternative thermodynamic cycles are actively studied. They allow to remove CO2, formed as a result of fuel combustion, from a cycle without significant energy costs. Calculations have shown that such cycles may meet or exceed the most advanced power plants in terms of heat efficiency. The Allam cycle is recognized as one of the best alternative cycles for the production of electricity. Nevertheless, a cycle of compressorless combined cycle gas turbine (CCGT) unit is seemed more promising for cogeneration of electricity and heat. A comparative analysis of the thermal efficiency of these two cycles was performed. Particular attention was paid to ensuring equal conditions for comparison. The cycle of compressorless CCGT unit was as close as possible to the Allam cycle due to the choice of parameters. The processes, in which the difference remained, were analysed. Thereafter, an analysis of how close the parameters, adopted for comparison, to optimal for the compressorless CCGT unit cycle was made. This analysis showed that these two cycles are quite close only for the production of electricity. The Allam cycle has some superiority but not indisputable. However, if cogeneration of electricity and heat is considered, the thermal efficiency of the cycle of compressorless CCGT unit will be significantly higher. Since it allows to independently regulate a number of parameters, on which the electric power, the ratio of electric and thermal power, the temperature of a working fluid at the turbine inlet depend. Thus, the optimal parameters of the thermodynamic cycle can be obtained in a wide range of operating modes of the unit with different ratios of thermal and eclectic powers. Therefore, the compressorless CCGT unit can significantly surpass the best steam turbine and combined cycle gas turbine plants in district heating system in terms of thermal efficiency.

scholarly journals РОЗРОБКА ВИСОКОЕФЕКТИВНОЇ СУДНОВОЇ СИСТЕМИ ОЧИЩЕННЯ ПОВІТРЯ ВІД КРАПЛИННОЇ ВОЛОГИ

2018 ◽  
pp. 42-46
Author(s):  
Анатолій Павлович Шевцов ◽  
Сергій Сергійович Рижков
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Reverse Flow ◽  
Surface Profile ◽  
Working Fluid ◽  
Efficient Design ◽  
Air Cleaning ◽  
Wide Range ◽  
Design Solutions ◽  
Condensed Moisture

It is investigated one of the directions of increasing the technical, economic and environmental characteristics of engines and power plants by air cleaning as a working fluid of condensed moisture. Prospective methods of aerosol medium separation with the help of gradient intensification of transfer processes in boundary layers of multifunctional surfaces are also investigated. Multifunctional surfaces include surfaces with a coefficient of compactness more than 2000 m2/m3, characterized by improved heat exchange and separating properties. A characteristic feature of the developed separating profiles is the combination of a waveform part with flat input and output elements. In the assembly, the separating profiles form the curved channels with a number of successive confuser and diffuser elements. In diffusor elements, there are separating zones with the gas reverse flow. The liquid film resulting from the droplets deposition, falling into these zones, is influenced by the vortices effect that counteracts the film motion in the direction of the main flow and facilitates its flow under the action of gravity. The investigations of gas dynamics and deposition coefficients of the separation profile were performed. The coefficient of droplets deposition for flow rates of 5, 10, 15, 20 m/s in separating profiles with a radius of 5, 10, 15, 20, 25 mm was calculated. It was determined that vortex zones provide full removal of captured water from the smooth surface profile up to the airspeed of 5 m/s. Excess of this speed leads to the removal of part of the water from the vortex zones. Drainage elements are provided for preventing secondary flooding of the flow in flat sections of the separation profile. Design solutions and a generalized scheme of the ship system of air cleaning of condensed moisture for the air flow from 20 to 2000 m3/h were developed. The introduction of filters based on gradient technologies will increase the reliability, the life of the marine power equipment and its elements. This will contribute to the creation of high-efficiency energy-saving technologies and efficient design solutions for a wide range of gradient marine power plant separators.

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