Efficiency optimisation of advanced gas turbine recuperative-cycles

2019 ◽  
Vol 234 (6) ◽  
pp. 817-835
Author(s):  
R Bontempo ◽  
M Manna
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Working Fluid ◽  
Pressure Losses ◽  
Intermediate Pressure ◽  
Compression And Expansion ◽  
Heat Recuperation ◽  
Simplifying Assumptions ◽  
Advanced Cycles ◽  
Analytical Approaches

The paper presents a theoretical analysis of three advanced gas turbine recuperative-cycles, that is, the intercooled, the reheat and the intercooled and reheat cycles. The internal irreversibilities, which characterise the compression and expansion processes, are taken into account through the polytropic efficiencies of the compressors and turbines. As customary in simplified analytical approaches, the study is carried out for an uncooled closed-circuit gas turbine without pressure losses in the heat exchangers and using a calorically perfect gas as working fluid. Although the accurate performance prediction of a real-gas turbine is prevented by these simplifying assumptions, this analysis provides a fast and simple approach which can be used to theoretically explain the main features of the three advanced cycles and to compare them highlighting pros and contra. The effect of the heat recuperation is investigated comparing the thermal efficiency of a given cycle type with those of two reference cycles, namely, the non-recuperative version of the analysed cycle and the simple cycle. As a result, the ranges of the intermediate pressure ratios returning a benefit in the thermal efficiency in comparison with the two reference cycles have been obtained for the first time. Finally, for the sole intercooled and reheat recuperative-cycle, a novel analytical expression for the intermediate pressure ratios yielding the maximum thermal efficiency is also given.

Determination of the optimum performance of gas turbines

2000 ◽  
Vol 214 (1) ◽  
pp. 243-255 ◽  
Author(s):  
J. H. Horlock ◽  
W. A. Woods
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Working Fluid ◽  
Optimum Conditions ◽  
Perfect Gas ◽  
Pressure Losses ◽  
Real Effects ◽  
Turbine Performance

Earlier analytical and graphical treatments of gas turbine performance, assuming the working fluid to be a perfect gas, are developed to allow for ‘non-perfect’ gas effects and pressure losses. The pressure ratios for maximum power and maximum thermal efficiency are determined analytically; the graphical presentations of performance based on the earlier approach are also modified. It is shown that the optimum conditions previously determined from the ‘air standard’ analyses may be changed quite substantially by the inclusion of the ‘real’ effects.

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.

System Study on Partial Gasification Combined Cycle With CO2 Recovery

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Yujie Xu ◽  
Hongguang Jin ◽  
Rumou Lin ◽  
Wei Han
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Energy Utilization ◽  
Working Fluid ◽  
The Novel ◽  
Integrated Gasification Combined Cycle ◽  
Partial Gasification ◽  
Co2 Recovery

A partial gasification combined cycle with CO2 recovery is proposed in this paper. Partial gasification adopts cascade conversion of the composition of coal. Active composition of coal is simply gasified, while inactive composition, that is char, is burnt in a boiler. Oxy-fuel combustion of syngas produces only CO2 and H2O, so the CO2 can be separated through cooling the working fluid. This decreases the amount of energy consumption to separate CO2 compared with conventional methods. The novel system integrates the above two key technologies by injecting steam from a steam turbine into the combustion chamber of a gas turbine to combine the Rankine cycle with the Brayton cycle. The thermal efficiency of this system will be higher based on the cascade utilization of energy level. Compared with the conventional integrated gasification combined cycle (IGCC), the compressor of the gas turbine, heat recovery steam generator (HRSG) and gasifier are substituted for a pump, reheater, and partial gasifier, so the system is simplified obviously. Furthermore, the novel system is investigated by means of energy-utilization diagram methodology and provides a simple analysis of their economic and environmental performance. As a result, the thermal efficiency of this system may be expected to be 45%, with CO2 recovery of 41.2%, which is 1.5–3.5% higher than that of an IGCC system. At the same time, the total investment cost of the new system is about 16% lower than that of an IGCC. The comparison between the partial gasification technology and the IGCC technology is based on the two representative cases to identify the specific feature of the proposed system. The promising results obtained here with higher thermal efficiency, lower cost, and less environmental impact provide an attractive option for clean-coal utilization technology.

Conceptual Investigation of a Small Reheat Gas Turbine System

2003 ◽  
Author(s):  
Norihiko Iki ◽  
Hirohide Furutani ◽  
Sanyo Takahashi
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Water Injection ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Micro Gas Turbine ◽  
Thermal Generator ◽  
Process Simulator ◽  
Characteristic Component

The mirror gas turbine proposed by Tsujikawa and Fujii extends the applications of turbo machinery. The characteristic component of a mirror gas turbine is a thermal generator, which is a kind of “inverted Brayton cycle”. The operating sequence of the thermal generator is reverse that of an ordinary gas turbine, namely, the hot working fluid is first expanded, and then cooled, compressed, and finally exhausted. In this work, we investigated the theoretical feasibility of inserting a thermal generator to a small reheat gas turbine of 30–100kW classes. Using process simulator software, we calculated and compared the thermal efficiency of this reheat gas turbine to that of a micro gas turbine under several conditions, turbine inlet temperature. This comparison showed that the performances of the both gas turbines are significantly influenced by the performance of the heat exchanger used for the recuperator. The efficiency of the micro gas turbine is also improved by using water injection into the compressor to cool the inlet gas. The resulting thermal efficiency of this reheat gas turbine is about 7% higher than that of a micro gas turbine with the same power unit.

System Study on Partial Gasification Combined Cycle With CO2 Recovery

2006 ◽  
Author(s):  
Yujie Xu ◽  
Hongguang Jin ◽  
Rumou Lin ◽  
Wei Han
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Energy Utilization ◽  
Working Fluid ◽  
The Novel ◽  
Attractive Option ◽  
Partial Gasification ◽  
Co2 Recovery

A partial gasification combined cycle with CO2 recovery is proposed in this paper. Partial gasification adopts cascade conversion of the composition of coal. Active composition of coal is simply gasified, while inactive composition, that is char, is burnt in a boiler. Oxy-fuel combustion of syngas produces only CO2 and H2O, so the CO2 can be separated through cooling the working fluid. This decreases the amount of energy consumed to separate CO2 compared with conventional methods. The novel system integrates the above two key technologies, by injecting steam from a steam turbine into the combustion chamber of a gas turbine, to combine the Rankine cycle with the Brayton cycle. The thermal efficiency of this system will be higher based on the cascade utilization of energy level. Compared to the conventional IGCC, the compressor of the gas turbine, HRSG and gasifier are substituted for a pump, reheater and partial gasifier, so the system is simplified obviously. Furthermore, the novel system is investigated by means of EUD (Energy-Utilization Diagram) methodology and provides a simple analysis of their economic and environmental performance. As a result, the thermal efficiency of this system may be expected to be 46%, with recovery of 50% of CO2, which is 3–5% higher than that of an IGCC system. At the same time, the total investment cost of the new system is about 21.5% lower than that of an IGCC. The promising results obtained here with higher thermal efficiency, lower cost and less environmental impact provide an attractive option for clean coal utilization technology.

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.

Research of characteristics of the flow part of an aerothermopressor for gas turbine intercooling air

2021 ◽  
pp. 095765092110579
Author(s):  
Dmytro Konovalov ◽  
Mykola Radchenko ◽  
Halina Kobalava ◽  
Andrii Radchenko ◽  
Roman Radchenko ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Relative Increase ◽  
Air Pressure ◽  
Pressure Increase ◽  
Working Fluid ◽  
Compression Process ◽  
Two Phase ◽  
Pressure Losses ◽  
Highly Dispersed

Complex gas turbine schemes with air intercooling are usually used to bring the compression process of working fluid in compressor closer to isothermal one. A promising way to realize it is to use an aerothermopressor. The aerothermopressor is a two-phase jet apparatus, in which the highly dispersed liquid (water) is injected into the superheated gas (air) stream accelerated to the speed closed to the sound speed value (Mach number from 0.8 to 0.9). The air pressure at the aerothermopressor outlet (after diffuser) is higher than at the inlet due to instantaneous evaporation of highly dispersed liquid practically without friction losses in mixing chamber and with an increase in pressure of the mixed homogenous flow. The liquid evaporation is conducted by removing the heat from the air flow. In the course of the experimental research, the operation of the aerothermopressor for gas turbine intercooling air was simulated and its characteristics (hydraulic resistance coefficients, pressure increase, and air temperature) were determined. Within contact cooling of air in the aerothermopressor, the values of the total pressure increase in the aerothermopressor were from 1.02 to 1.04 (2–4%). Thus, the aerothermopressor use to provide contact evaporative cooling of cyclic air between the compressor stages will ensure not only compensation for pressure losses but also provides an increase in total air pressure with simultaneous cooling. Injection of liquid in a larger amount than is necessary for evaporation ensures a decrease in pressure losses in the flow path of the aerothermopressor by 15–20%. When the amount of water flow is more than 10–15%, the pressure loss becomes equal to the loss for the “dry” aerothermopressor, and with a further increase in the amount of injected liquid, they are exceeded. The values of errors in the relative increase of air pressure in the aerothermopressor measurements not exceeded 4%. The results obtained can be used in the practice of designing intercooling systems for gas turbines.

Comparative Study of Two Low CO2 Emission Cycle Options With Natural Gas Reforming

2007 ◽  
Author(s):  
Na Zhang
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Co2 Emission ◽  
Internal Heat ◽  
Working Fluid ◽  
Co2 Removal ◽  
Exhaust Heat ◽  
Natural Gas Reforming ◽  
Turbine Exhaust

Two power plant schemes with natural gas reforming and CO2 emission reduction were analyzed and discussed. The first one integrates natural gas reforming technology with an oxy-fuel combined power cycle (OXYF-REF), with water as the main work fluid. The reforming heat is obtained from the available turbine exhaust heat, and the produced syngas is used as fuel with oxygen as the oxidizer. The turbine working fluid can expand down to a vacuum, producing a high pressure ratio. The second system adopts pre-combustion decarbonization and a chemical absorption technology for CO2 removal (PCD-REF). The gas turbine is the conventional air based one with compressor intercooling. Supplementary combustion is adopted to elevate the turbine exhaust temperature and thus achieve a much higher methane conversion rate (∼95%). Both cycles involve internal heat recuperation from gas turbine exhausts, and particular attention has been put on the integration of heat recovery chain to reduce the related exergy destruction. The systems are simulated and compared in terms of both thermal efficiency and CO2 removal. The OXYF-REF cycle has shown better performance with higher levels of CO2 removal and energy efficiency of 52%. The PCD-REF cycle showed a thermal efficiency of 43% and CO2 specific emission of 55.5 g/kWh.

Evaluation of the Effect of Firing Temperature, Cycle, Engine Configuration, Components, and Bottoming Cycle on the Overall Thermal Efficiency of an Indirectly Coal-Fired Gas Turbine Based Power Plant

2006 ◽  
Author(s):  
Richard P. Johnston
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Power Plants ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Turbine Engine ◽  
Combined Cycle Plant ◽  
Plant Power

Potential LHV performance of an indirect coal-fired gas turbine-based combined cycle plant is explored and compared to the typical LHV 35–38 % thermal efficiencies achievable with current coal-fired Rankine Cycle power plants. Plant performance with a baseline synchronous speed, single spool 25:1 pressure ratio gas turbine with a Rankine bottoming cycle was developed. A coal-fired High Temperature Advanced Furnace (HITAF) supplying 2000° F. (1093° C.) hot pressurized air for the gas turbine was modeled for the heat source. The HITAF concept along with coal gas for supplemental heating, are two important parts of the clean coal technology program for power plants. [1,2] From this baseline power plant arrangement, different gas turbine engine configurations with two pressure ratios are evaluated. These variations include a dual spool concentric shaft gas turbine, dual spool non-concentric shaft arrangement, intercooler, liquid metal loop re-heater, free power turbine (FPT) and post HITAF duct burner (DB). A dual pressure Heat Recovery Steam Generator (HRSG) with varying steam pressures to fit conditions is used for each engine. A novel steam generating method employing flash tank technology is applied when a water-cooled intercooler is incorporated. A halogenated hydrocarbon working fluid is also evaluated for lower temperature sub-bottoming Rankine cycle equipment. Current technology industrial gas turbine component performance levels are applied to these various engines to produce a range of LHV gross gas turbine thermal efficiency estimates. These estimates range from the lower thirties to over forty percent. Overall LHV combined cycle plant gross thermal efficiencies range from nearly forty to over fifty percent. All arrangements studied would produce significant improvements in thermal efficiency compared to current coal-fired Rankine cycle power plants. Regenerative inter-cooling, free power turbines, and dual-spool non-concentric shaft gas turbine arrangements coupled with post-HITAF duct burners produced the highest gas turbine engine and plant efficiency results. These advanced engine configurations should also produce operational benefits such as easier starting and much improved part power efficiency over the baseline engine arrangement. An inter-turbine liquid metal re-heat loop reduced engine thermal efficiency but did increase plant power output and efficiency for the example studied. Use of halogenated hydrocarbons as a working fluid would add to plant power output, but at the cost of significant additional plant equipment.

The Basic Thermodynamics of Turbine Cooling

2000 ◽  
Vol 123 (3) ◽  
pp. 583-592 ◽  
Author(s):  
J. H. Horlock
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Combustion Temperature ◽  
Plant Performance ◽  
Maximum Temperature ◽  
Working Fluid ◽  
Turbine Plant ◽  
Cooling Flows ◽  
Turbine Cooling ◽  
Gas Turbine Plant

Analyses of gas turbine plant performance, including the effects of turbine cooling, are presented. The thermal efficiencies are determined theoretically, assuming air standard (a/s) cycles, and the reductions in efficiency due to cooling are established; it is shown that these are small, unless large cooling flows are required. The theoretical estimates of efficiency reduction are compared with calculations, assuming that real gases form the working fluid in the gas turbine cycles. It is shown from a/s analysis that there are diminishing returns on efficiency as combustion temperature is increased; for real gases there appears to be a limit on this maximum temperature for maximum thermal efficiency.

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