Steam Injected Gas Turbine Cycle Research Articles

Parameter evaluation for a hybrid marine system combining solid oxide fuel cells and overexpanded steam-injected gas turbine

The article focuses on the development of decarbonized marine power systems, consisting of solid oxide fuel cells (SOFC) and gas turbines (GT), aiming to provide high economic and environmental performance. Currently, the potential of such systems is not fully realized due to issues related to the insufficient reliability and durability of the fuel cells themselves, as well as suboptimal heat utilization processes in the gas turbine section of the power plant. In contrast to previous research, this study demonstrates the prospects of using the steam-injected gas turbine (STIG) cycle and overexpanded turbine to improve the heat recovery conditions of exhaust gasses from fuel cells, enhance the efficiency of the power system, and increase the longevity of its key components. To achieve this, a corresponding mathematical model was developed, and optimization calculations for the proposed system cycle were conducted. Adopting the proposed cycle with a steam-injected gas turbine resulted in a 4.4 % increase in efficiency compared to traditional schemes. Such a system could be utilized in the design of advanced marine power system for the next generation.

Thermodynamic performance study of a new diesel-fueled CLHG/SOFC/STIG cogeneration system with CO2 recovery

A new type of diesel-fueled cogeneration system is proposed in this study. The system mainly includes solid oxide fuel cell, chemical looping hydrogen generation and steam injection gas turbine cycle. The system can effectively avoid the carbon deposition of solid oxide fuel cell, recovering CO2 without separation energy consumption. Additionally, it adopts the way of centralized supply of steam and air, thus reducing the complexity and loss of the system. On this basis, the system is comprehensively evaluated by sensitivity analysis, exergy analysis, energy utilization diagram analysis and exergoeconomic analysis. It is found that the total power efficiency, exergy efficiency and fuel energy saving ratio of the new system can reach 64%, 60% and 60% respectively. Meanwhile, the power production cost of the new system is 51.25 $/GJ, and the optimization suggestion of the system is given according to the result of exergoconomic analysis. The proposed system provides a theoretical basis and new idea for the design and construction of diesel-fueled energy supply system.

Advanced Exergy and Exergoeconomic Analysis of a Gas Power System with Steam Injection and Air Cooling with a Compression Refrigeration Machine

Gas turbine power plants have been widely studied, and as a result the negative effects on their output power and thermal efficiency have been known when operating in atmospheric conditions exceeding ISO conditions. For this reason, different technologies and methodologies have been implemented, aiming to increase the output power and improve the thermal efficiency. Unfortunately, the lack of operational parameters for this system limited its characterization and implementation of strategies to improve its performance. Advanced exergetic and exergoeconomic analyses have been applied to improve energy and economic performance in steam injection gas turbine (STIG) cycle power plants with air cooling with a compression refrigeration machine. Results shows that the main sources of irreversibilities and higher costs are in the Combustion Chamber (CC), Heat Recovery Steam Generator (HRSG) and Gas Turbine (GT). From these components, the components of the HRSG and GT have the greatest potential for improvement, and this can be achieved by improving the overall configuration of the system, due to the fact that the destruction of exogenous exergy is in more significant measure avoidable. While the higher costs of investment can be reduced in the Combustion Chamber and Gas Turbine.

Thermoenvironomic evaluation of simple, intercooled, STIG, and ISTIG cycles

Low-technology cycle modifications available for improving gas turbine performance are still largely unexploited. Among those proven modifications, steam injection is found to be the most effective in boosting both the output capacity and thermal efficiency while reducing NOx emissions. It further improves part load performance under varying ambient conditions. Intercooling is another low-technology modification which can improve performance of simple and steam injected gas turbine cycles. Because of the uncertainties relating to an efficiency comparison of steam injected and simple cycle designs, the decision as to whether it is worthwhile to give more emphasis to steam injected cycles should be made on grounds other than efficiency alone. Therefore, this study comparatively evaluates simple, intercooled, steam injected (STIG), and intercooled steam injected (ISTIG) gas turbine cycles from the points of efficiency, network output, economics, and pollutant emissions using an advanced validated thermoenvironomic model. Optimum cycle parameters are investigated. Economic feasibility of steam injection and intercooling on simple and intercooled cycles are evaluated using an updated plant cost data. Total and environmental costs as well as profit of the plant owner are estimated for varying fuel costs and varying cycle parameters such as pressure, steam injection, and equivalence ratio. Results of our analysis based on the characteristic cycle parameters show that network output increases up to 22.2% and 14% respectively, when steam injection is implemented on simple and intercooled gas turbine cycles which correspond to up to 6.7% and 4.4% decrease in specific fuel consumption. Steam injection decreases NOx emissions of simple and intercooled cycles up to 67.2% and 65.2% respectively, and provides up to approximately 126.3% increase in net profit of intercooled cycle at the expense of an increase in total cost by 3.3%.

Thermodynamic analysis of steam-injected advanced gas turbine cycles

This paper deals with thermodynamic analysis of steam-injected gas turbine (STIGT) cycle. To analyse the thermodynamic performance of steam-injected gas turbine (STIGT) cycles, a methodology based on pinch analysis is proposed. This graphical methodology is a systematic approach proposed for a selection of gas turbine with steam injection. The developed graphs are useful for selection of steam-injected gas turbine (STIGT) for optimal operation of it and helps designer to take appropriate decision. The selection of steam-injected gas turbine (STIGT) cycle can be done either at minimum steam ratio (ratio of mass flow rate of steam to air) with maximum efficiency or at maximum steam ratio with maximum net work conditions based on the objective of plants designer. Operating the steam injection based advanced gas turbine plant at minimum steam ratio improves efficiency, resulting in reduction of pollution caused by the emission of flue gases. On the other hand, operating plant at maximum steam ratio can result in maximum work output and hence higher available power.

Assessment of Solar Gas Turbine Hybridization Schemes

A simulation environment allowing steady state and transient modeling is used for assessing several gas turbine based cycles proposed for solar hybridization. First, representative open cycle gas turbine configurations, namely, (a) single shaft (SS), (b) recuperated single-shaft, (c) twin shaft (TS), and (d) two-spool three-shaft, intercooled, recuperated, are evaluated. The importance of design point selection in terms of solar share value is highlighted. Solar steam injection gas turbine cycle (STIG) alternatives, namely, solar steam only and solar/fuel gas steam, are then assessed. Finally, the concept of a dual fluid receiver (DFR) for exploiting the rejected solar power by producing steam during sunny hours with high irradiation is demonstrated. The effects of hybridization on performance and operability are established and evaluated. Solarization effect on performance is estimated in terms of annual produced power and fossil fuel savings. The results indicate that the spool arrangement affects the suitability of a gas turbine for hybridization. Recuperated configurations performed better for the design constrains imposed by current technology solar parts. Solar steam injection is a promising solution for retrofitted fuel-only and conventional STIG engines.

Thermodynamic Analysis on Steam Injected Gas Turbine cycle

This paper presents thermodynamic methodology for the performance evaluation of steam injected gas turbine(STIG) cycle. The effects of pressure ratio, turbine inlet temperature and specific mass flow rate of steam per kg of air used in the thermodynamic analysis of steam injected gas turbine(STIG) cycle on thermal efficiency of the cycle, specific work output and specific fuel consumption have been investigated. From the results obtained in graphs it is observed that thermal efficiency of steam injected gas turbine(STIG) cycle increases and net work output increases and specific fuel consumption decreases as pressure ratio increases; thermal efficiency of steam injected gas turbine(STIG) cycle and specific work output increases with increase in turbine inlet temperature. Results also show that STIG cycle efficiency is always greater than simple gas turbine cycle for same pressure ratio and turbine inlet temperature and for wide range of parameters STIG cycle is superior to simple gas turbine cycle. In STIG cycle as specific mass flow rate per kg of air increases cycle efficiency and net work output also increases.

Thermodynamic analysis of steam-injected gas turbine cycle power plant with inlet air cooling

Steam-injected gas turbine cycle is the modified arrangement of simple gas turbine (GT) cycle, wherein part of steam generated in a heat recovery steam generator is injected into the combustion chamber to increase power output and the efficiency. This paper studies the effect of integration of inlet air cooling, steam injection (SI) and film cooling (FC) on the performance of GT cycle. Two different methods for cooling the inlet air, namely inlet fogging and evaporative cooling, are considered for analysis here. Results show that the inlet fogging is better than evaporative cooling to achieve the lowest temperature at the compressor inlet. Thermodynamic performance of simple GT cycle is also compared with SI in GT cycle. The present study shows that GT cycle with integration of inlet fogging, SI and FC is a better configuration for achieving higher performance.

Effect of mist cooling technique on exergy and energy analysis of steam injected gas turbine cycle

The common cogeneration application is steam injected gas turbine. By using cogeneration, it can be obtained with the greatest benefit from fuel energy. In steam injected gas turbine the heat of exhaust gases is used to produce the steam, and this steam injects to combustion chamber. In the present work, the generated steam not only will be directed to the combustion chamber but also will be used to cool the blade turbine by using a closed loop. In this study, the effect of addition mist to steam as coolant fluid was investigated. The energy and exergy analyses for steam injected gas turbine cycle with a closed loop cooling technique by using steam and steam/mist were investigated. The investigation was made at varied values of steam coolant temperature, mist fraction, mist temperature, pressure ratio, turbine inlet temperature and blade temperature. These parameters affected network, plant efficiency, energy ratio, fuel conversion ratio and exergy efficiency. The results show that the efficiency can reach 47.2% at low coolant temperature with a mist fraction of 2%. The coolant heat gain is enhanced at lower mist temperature, so the blade surface temperature can be improved with mist addition to steam. At a mist fraction of 2% exergy efficiency is decreased by 0.03% than that for exergy efficiency of steam only.

Annual energy and environment analysis of solarized steam injection gas turbine (STIG) cycle for Indian regions

The solarized steam injection gas turbine (STIG) cycle uses both the fuel and solar heat simultaneously for power generation. The annual thermodynamic performances of the cycle for sites in India with local climatic conditions such as ambient temperature, relative humidity and availability of direct normal irradiance (DNI) to the solar concentrators under two modes of constant and variable power are presented in this paper. The results reveal that the solar to electricity efficiency of solar hybrid STIG plant with a simple parabolic trough collector (PTC) is similar to existing solar thermal technologies, and also higher solar share is obtained. The study also reveals that the annual CO2 emission is similar to combined cycle plants and lower than gas turbine technologies. The incremental CO2 avoidance is also computed due to solar participation. The annual values of exergetic solar fraction and exergetic efficiency at Indore are higher than Jaipur. Results of an improved economic assessment show that the levelized tariff (LT) of solar hybrid STIG plant is 0.2–0.23 $/kWh and the levelized tariff (solar only) or solar levelized tariff (SLT) of solar STIG plant ranges from 0.11 to 0.27 $/kWh for both constant and variable power scenarios.

Comparative Exergoeconomic Analyses of Gas Turbine Steam Injection Cycles with and without Fogging Inlet Cooling

The results are reported of exergoeconomic analyses of a simple gas turbine cycle without a fogging system (SGT), a simple steam injection gas turbine cycle (STIG), and a steam injection gas turbine cycle with inlet fogging cooler (FSTIG). The results show that (1) a gas-turbine cycle with steam injection and simultaneous cooling has a higher power output than the other considered cycle; (2) at maximum energy efficiency conditions the gas turbine has the highest exergy efficiency of the cycle components and the lowest value of exergy efficiency is calculated for the fog cooler, where the mixing of air and water at greatly different temperatures causes the high exergy destruction; and (3) utilization of the fogging cooler in the steam injection cycle increases the exergy destruction in the combustion chamber. Furthermore, the simple gas turbine cycle is found to be more economic as its relative cost difference, total unit product cost, and exergoeconomic factors are less than those for the two other configurations. However, its efficiency and net power output are notably lower than for the gas turbine with steam injection and/or fog cooling. The total unit product cost is highest for the simple gas turbine with steam injection.

Performance analysis of a partial oxidation steam injected gas turbine cycle

Partial oxidation gas turbine (POGT) has great potential in improving efficiency because of staged releasing of the chemical energy of fuel. Several researchers have studied the applications of POGT in repowering of different existing power plants. In this study, the POGT is integrated with a steam injected gas turbine (STIG) cycle. This research evaluated the overall thermodynamic performance of a partial oxidation steam injected gas turbine (POSTIG) cycle and investigated the influences of key variables. In addition, comparisons with the STIG cycle were conducted based on exergy analysis. Results show that the combustor outlet temperature of the bottoming gas turbine cycle, the pressure ratio of the bottoming gas turbine cycle compressor, and the temperature of partial oxidation affected the efficiency and specific work output of the POSTIG cycle obviously. Compared with the simple gas turbine cycle, the oxygen concentration in the combustor outlet gas of the POSTIG cycle decreases significantly, and the cooling flow rate increases. Efficiency of the POSTIG cycle is at least two percentage points higher than that of the STIG cycle because of the production and utilization of higher quality steam, along with lower exergy destruction during the graded release of the fuel's chemical energy.

Performance of the solar hybrid STIG cycle with latent heat storage

Abstract The solar hybrid Steam Injection Gas turbine (STIG) cycle uses both recuperated heat and solar heat in order to generate steam at a low temperature and pressure, and inject it into the cycle in order to augment the power output. This work addresses the addition of thermal energy storage to allow operation from solar energy beyond the daylight hours. An annual performance analysis of the Solar STIG cycle with latent heat phase change material (PCM) storage is presented for the climatic conditions of Sede Boqer, Israel. We show that the heat transfer limitation present in a real PCM storage leads to a slight performance penalty only compared to an ideal storage. We also analyze the impact of shifting electricity generation from daytime to evening, which can lead to a surprisingly high contribution of the thermal storage. Results show annual solar fraction of up to 35.2%. The annual solar to electricity efficiency was 20.1% when using the recuperated Brayton cycle as reference, and 13.9% for an optimal conventional STIG cycle as reference. These values are similar to or higher than the annual efficiency of current solar thermal power technologies, even though the hybrid STIG cycle uses low-grade solar heat at 200–280 °C.

Thermodynamic Analysis of a Power Plant Integrated with Fogging Inlet Cooling and a Biomass Gasification

Biomass energy and especially biofuels produced by biomass gasification are clean and renewable options for power plants. Also, on hot days the performance of gas turbines decreases substantially, a problem that can be mitigated by fog cooling. In the present paper, a biomass-integrated fogging steam injected gas turbine cycle is analyzed with energy and exergy methods. It is observed that (1) increasing the compressor pressure ratio raises the air flow rate in the plant but reduces the biomass flow rate; (2) increasing the gas turbine inlet temperature decreases the air and biomass flow rates; (3) increasing the compressor pressure ratio raises the energy and exergy efficiencies, especially at lower pressure ratios; (4) increasing the gas turbine inlet temperature raises both efficiencies; and (5) overspray increases the energy efficiency and net cycle power slightly. The gas turbine exhibits the highest exergy efficiency of the cycle components and the combustor the lowest. A comparison of the cycle with similar cycles fired by natural gas and differently configured cycles fueled by biomass shows that the cycle with natural gas firing has an energy efficiency 18 percentage points above the biomass fired cycle, and that steam injection increases the energy efficiency about five percentage points relative to the cycle without steam injection. Also, the influence of steam injection on energy efficiency is more significant than fog cooling.

Performance and environment as objectives in multi-criterion optimization of steam injected gas turbine cycles

Rapidly growing demand for gas turbines promotes research on their performance improvement and reducing their exhaust pollutants. Even small increments in net power or thermal efficiency and small changes in pollutant emissions have become significant concerns for both new designs and cycle modifications. To fulfill these requirements an accurate performance evaluation method which enables to see the effects on the exhaust gas composition is an important necessity. To fill this gap, a thermo-ecologic performance evaluation approach for gas turbine cycles with chemical equilibrium approximation which enables performance and environmental aspects to be considered simultaneously, is presented in this work. Steam injection is an effective modification to boost power and limit NOx emissions for gas turbine systems. Steam injection also increases thermal efficiency so less fuel is burnt to maintain the same power output. Because of its performance related and environmental advantages, presented approach is applied on the steam injected gas turbine cycle and a precise multi-criterion optimization is carried out for varying steam injection, as well as equivalence and pressure ratios. Irreversibilities and pressure losses are also considered. Effects of each parameter on the net work and thermal efficiency as well as non-equilibrium NOx and CO emissions are demonstrated. Precision improvement of the presented thermo-ecological model is shown and two main concerns; constant turbine inlet condition for higher net work output and constant net work output condition for lower fuel consumption are compared.

Annual performance of the solar hybrid STIG cycle

The solar hybrid Steam Injection Gas turbine (STIG) cycle uses both recuperated heat and solar heat in order to generate steam at a low temperature and pressure, and inject it into the cycle in order to augment the power output. An annual performance analysis of the Solar STIG cycle is presented for sites in Israel and India, with moderate and high annual direct insolation. The cycle operation was simulated in two modes: constant power output and variable power output following the variation of solar input. The solar contribution to the electricity production of the hybrid cycle and the solar to electricity efficiency were calculated, where the conventional reference system was either a conventional STIG or a conventional recuperated Brayton cycle. Results show annual solar fraction of up to 31% in constant power mode and up to 33% in variable power mode. The annual solar to electricity efficiency was in the range of 22–26% when the reference efficiency was based on the recuperated Brayton cycle, and 12–16% when the reference efficiency was based on an optimal conventional STIG cycle. These values are similar to or higher than the annual efficiency of current solar thermal power technologies, even though the hybrid STIG cycle uses low-grade solar heat at only 200°C.

Annual Thermodynamic Analysis of Solar Power with Steam Injection Gas Turbine (STIG) Cycle for Indian Conditions

Solar thermal energy is now being widely utilized to meet the world's energy demand due to its huge potential. Power generation from solar is varying and high cost of solar thermal energy systems that makes sense only in regions with high solar insolation. In order to overcome these practical issues, low cost solar hybrid steam injection gas turbine (STIG) cycle is adapted. Both gas turbine exhaust stream and solar heat are used for steam generation, and then it is injected into the combustor. The steam injection reduces NOX and CO2 emission in addition to increased power output and plant efficiency compared to the simple cycle. It offers a path for high conversion efficiency without the requirement of operating at high temperature and high pressure in the solar components. The objective of the proposed work is to investigate a conversion method for solar radiation that offers potentially high conversion efficiency and for increased competitiveness against fossil fuels. The annual performance of the cycle for sites in India with local climatic conditions such as ambient temperature, relative humidity and availability of direct normal irradiance to the solar concentrators under two modes of constant and variable power is presented in this paper. The results reveal that the solar to electricity efficiency of solar hybrid STIG plant with a simple Parabolic Trough Collector (PTC) is similar to existing solar thermal technologies and higher solar share is obtained. The study also reveals that the annual CO2 emission is similar to combined cycle plants and lower than gas turbine technologies.

Performance and Water Consumption of the Solar Steam-Injection Gas Turbine Cycle

Solar heat at moderate temperatures around 200 °C can be utilized for augmentation of conventional steam-injection gas turbine power plants. Solar concentrating collectors for such an application can be simpler and less expensive than collectors used for current solar power plants. We perform a thermodynamic analysis of this hybrid cycle, focusing on improved modeling of the combustor and the water recovery condenser. The cycle's water consumption is derived and compared to other power plant technologies. The analysis shows that the performance of the hybrid cycle under the improved model is similar to the results of the previous simplified analysis. The water consumption of the cycle is negative due to water production by combustion, in contrast to other solar power plants that have positive water consumption. The size of the needed condenser is large, and a very low-cost condenser technology is required to make water recovery in the solar STIG cycle technically and economically feasible.

Solar hybrid steam injection gas turbine (STIG) cycle

Abstract Solar heat at moderate temperatures around 200 °C can be utilized for augmentation of conventional steam-injection gas turbine power plants. Solar concentrating collectors for such an application can be simpler and less expensive than collectors used for current solar power plants. We perform a thermodynamic analysis of this hybrid cycle. High levels of steam-to-air ratio are investigated, leading to high power augmentation compared to the simple cycle and to conventional STIG. The Solar Fraction can reach up to 50% at the highest augmentation levels. The overall conversion efficiency from heat to electricity (average over fuel and solar contributions) can be in the range of 40–55% for typical candidate turbines. The incremental efficiency (corresponding to the added steam beyond conventional STIG) is in the range of 22–37%, corresponding to solar-to-electricity efficiency of about 15–24%, similar to and even exceeding current solar power plants using higher temperature collectors. The injected water can be recovered and recycled leading to very low water consumption of the cycle, but a very low cost condenser is required to make water recovery feasible.

A Parametric Thermodynamic Evaluation of High Performance Gas Turbine Based Power Cycles

This paper discusses the gas turbine performance enhancement approach that has gained a lot of momentum in recent years in which modified Brayton cycles are used with humidification or water/steam injection, termed “wet cycles,” or with fuel cells, obtaining “hybrid cycles.” The investigated high performance cycles include intercooled steam-injected gas turbine cycle, recuperated water injection cycle, humidified air turbine cycle, and cascaded humidified advanced turbine cycle, Brayton cycle with high temperature fuel cells (molten carbonate fuel cells or solid oxide fuel cells), and their combinations with the modified Brayton cycles. Most of these systems, with a few exceptions, have not yet become commercially available as more development work is required. The results presented show that the cycle efficiency achievable with the aforementioned high performance systems can be comparable or better than a combined cycle system, a currently commercially available power generation system having maximum cycle efficiency. The main emphasis of this paper is to provide a detailed parametric thermodynamic cycle analysis, using uniform design parameters and assumptions, of the above mentioned cycles and discuss their comparative performance including advantages and limitations. The performance of these cycles is also compared with the already developed and commercially available gas turbines without water/steam injection features, called “dry cycles.” In addition, a brief review of the available literature of the identified high performance complex gas turbine cycles is also included in this paper.