A Thermodynamic Analysis of Different Options to Break 60% Electric Efficiency in Combined Cycle Power Plants

2004 ◽  
Vol 126 (4) ◽  
pp. 770-785 ◽  
Author(s):  
Paolo Chiesa ◽  
Ennio Macchi
Keyword(s):  
Gas Turbine ◽  
Thermodynamic Analysis ◽  
Gas Turbines ◽  
Power Plants ◽  
Closed Loop ◽  
Open Loop ◽  
Combined Cycle ◽  
Rotor Blades ◽  
Air Cooling ◽  
Large Size

All major manufacturers of large size gas turbines are developing new techniques aimed at achieving net electric efficiency higher than 60% in combined cycle applications. An essential factor for this goal is the effective cooling of the hottest rows of the gas turbine. The present work investigates three different approaches to this problem: (i) the most conventional open-loop air cooling; (ii) the closed-loop steam cooling for vanes and rotor blades; (iii) the use of two independent closed-loop circuits: steam for stator vanes and air for rotor blades. Reference is made uniquely to large size, single shaft units and performance is estimated through an updated release of the thermodynamic code GS, developed at the Energy Department of Politecnico di Milano. A detailed presentation of the calculation method is given in the paper. Although many aspects (such as reliability, capital cost, environmental issues) which can affect gas turbine design were neglected, thermodynamic analysis showed that efficiency higher than 61% can be achieved in the frame of current, available technology.

A Thermodynamic Analysis of Different Options to Break 60% Electric Efficiency in Combined Cycle Power Plants

2002 ◽  
Author(s):  
Paolo Chiesa ◽  
Ennio Macchi
Keyword(s):  
Gas Turbine ◽  
Thermodynamic Analysis ◽  
Gas Turbines ◽  
Power Plants ◽  
Closed Loop ◽  
Open Loop ◽  
Combined Cycle ◽  
Rotor Blades ◽  
Air Cooling ◽  
Large Size

All major manufacturers of large size gas turbines are developing new techniques aimed at achieving net electric efficiency higher than 60% in combined cycle applications. An essential factor for this goal is the effective cooling of the hottest rows of the gas turbine. The present work investigates three different approaches to this problem: (i) the most conventional open-loop air cooling; (ii) the closed-loop steam cooling for vanes and rotor blades; (iii) the use of two independent closed-loop circuits: steam for stator vanes and air for rotor blades. Reference is made uniquely to large size, single shaft units and performance is estimated through an updated release of the thermodynamic code GS, developed at the Energy Dept. of Politecnico di Milano. A detailed presentation of the calculation method is given in the paper. Although many aspects (such as reliability, capital cost, environmental issues) which can affect gas turbine design were neglected, thermodynamic analysis showed that efficiency higher than 61% can be achieved in the frame of current, available technology.

Development of the Transpiration Air-Cooled Turbine for High-Temperature Dirty Gas Streams

1983 ◽  
Vol 105 (4) ◽  
pp. 821-825 ◽  
Author(s):  
J. Wolf ◽  
S. Moskowitz
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Specific Power ◽  
Skin Permeability ◽  
Air Cooling ◽  
Initial Exposure ◽  
Flow Capacity

Studies of combined cycle electic power plants have shown that increasing the firing temperature and pressure ratio of the gas turbine can substantially improve the specific power output of the gas turbine as well as the combined cycle plant efficiency. Clearly this is a direction in which we can proceed to conserve the world’s dwindling petroleum fuel supplies. Furthermore, tomorrow’s gas turbines must do more than operate at higher temperature; they will likely face an aggressive hot gas stream created by the combustion of heavier oils or coal-derived liquid or gaseous fuels. Extensive tests have been performed on two rotating turbine rigs, each with a transpiration air cooled turbine operating in the 2600 to 3000°F (1427 to 1649°C) temperature range at increasing levels of gas stream particulates and alkali metal salts to simulate operation on coal-derived fuel. Transpiration air cooling was shown to be effective in maintaining acceptable metal temperatures, and there was no evidence of corrosion, erosion, or deposition. The rate of transpiration skin cooling flow capacity exhibited a minor loss in the initial exposure to the particulate laden gas stream of less than 100 hours, but the flow reduction was commensurate with that produced by normal oxidation of the skin material at the operating temperatures of 1350°F (732°C). The data on skin permeability loss from both cascade and engine tests compared favorably with laboratory furnace oxidation skin specimens. To date, over 10,000 hr of furnace exposure has been conducted. Extrapolation of the data to 50,000 hr indicates the flow capacity loss would produce an acceptable 50°F (10°C) increase in skin operating temperature.

scholarly journals Effects of Leading-Edge Modification in Damaged Rotor Blades on Aerodynamic Characteristics of High-Pressure Gas Turbine

Mathematics ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 2191
Author(s):  
Thanh Dam Mai ◽  
Jaiyoung Ryu
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Leading Edge ◽  
Combined Cycle ◽  
Rotor Blades ◽  
Sudden Increase ◽  
Damage Location

The flow and heat-transfer attributes of gas turbines significantly affect the output power and overall efficiency of combined-cycle power plants. However, the high-temperature and high-pressure environment can damage the turbine blade surface, potentially resulting in failure of the power plant. Because of the elevated cost of replacing turbine blades, damaged blades are usually repaired through modification of their profile around the damage location. This study compared the effects of modifying various damage locations along the leading edge of a rotor blade on the performance of the gas turbine. We simulated five rotor blades—an undamaged blade (reference) and blades damaged on the pressure and suction sides at the top and middle. The Reynolds-averaged Navier–Stokes equation was used to investigate the compressible flow in a GE-E3 gas turbine. The results showed that the temperatures of the blade and vane surfaces with damages at the middle increased by about 0.8% and 1.2%, respectively. This causes a sudden increase in the heat transfer and thermal stress on the blade and vane surfaces, especially around the damage location. Compared with the reference case, modifications to the top-damaged blades produced a slight increase in efficiency about 2.6%, while those to the middle-damaged blades reduced the efficiency by approximately 2.2%.

scholarly journals Gas Turbine Uprating Programme Development and Testing of the GT11NM

1998 ◽  
Author(s):  
Christoph Schneider ◽  
Vladimir Navrotsky ◽  
Prith Harasgama
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Development Program ◽  
Combined Cycle ◽  
Economic Life ◽  
Air Cooling ◽  
Performance Improvements ◽  
Cooling Technology ◽  
Improved Performance

ABB has approximately 200 GT11N and GT11D type gas turbines currently operating in simple cycle and combined cycle power plants. Most of these machines are fairly mature with many approaching the end of their economic life. In order that the power producer may continue to operate a fleet with improved performance, Advanced Air Cooling Technology and Advanced Turbine Aerodynamics have been utilized to uprate these engines with the implementation of a completely new turbine module. The objective of the uprating program was to implement the advanced aero/cooling technology into a complete new turbine module with: • Improved power output for the gas turbine • Increase the GT cycle efficiency • Maintain or improve the gas turbine RAM (Reliability, Availability & Maintainability) • Reduce the Cost of Electricity • Maintain or reduce the emissions of the gas turbine The GT11NM gas turbine has been developed based on the GT11N which has been in operation since 1987 and Midland Cogeneration Venture (MCV-Midland, Michigan) was chosen to demonstrate the uprated GT11NM. The upate/retrofit of the GT11N engine was conducted in May/June 1997 and the resulting gas turbine - GT11NM has met and exceeded the performance goals set at the onset of the development program. The next sections detail the main changes to the turbine and the resulting performance improvements as established with the demonstration at Midland, Michigan.

Update on Mitsubishi G Series Gas Turbines With Over 78,000 Hours Fleet Operation

2003 ◽  
Author(s):  
V. Kallianpur ◽  
D. Stacy ◽  
Y. Fukuizumi ◽  
H. Arimura ◽  
S. Uchida
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Operating Time ◽  
Operating Experience ◽  
Combined Cycle ◽  
Air Cooling ◽  
Commercial Operation ◽  
Advanced Stages ◽  
Steam Cooling

Seven G gas turbines from Mitsubishi are in commercial operational at various combined cycle power plants since the first Mitsubishi G gas turbine was inroduced in 1997. The combined operating time on the fleet exceeds over 78,000 actual hours. Additional power plants using Mitsubishi G-series gas turbines are in advanced stages of commissioning in the U.S.A., and are expected to be in commercial operation in 2003. This paper describes operating experience of the Mitsubishi G-series gas turbines, which apply steam-cooling instead of air-cooling to cool the combustor liners. The paper discusses design enhancements that were made to the lead M501G gas turbine at Mitsubishi’s in-house combined cycle power plant facility. It also addresses the effectiveness of those enhancements from the standpoint of hot parts durability and reliability at other power plants that are in commercial operation using Mitsubishi G gas turbines.

Water-Free Combined Cycle Power Plants for Distributed Power Generation

2018 ◽  
Author(s):  
Michael Welch
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Combined Cycle ◽  
Air Cooling ◽  
Exhaust Gas ◽  
Plant Design ◽  
Distributed Power ◽  
Full Load

Combined Cycle Gas Turbine (CCGT) power plant offer operators both environmental and economic benefits. The high efficiency achievable across a wide load range reduces both fuel costs and CO2 emissions to atmosphere. However, the scale of the power generation plays a major role in determining both cost and efficiency: a modern large centralized CCGT of 600MW output or more will have a full load efficiency in excess of 60% and a very competitive installed cost on a US$/kW basis. The smaller gas turbines required for distributed power applications are not optimized for combined cycle operation, with potential full load efficiencies of a combined cycle scheme ranging from a little over 40% to the high 50s depending on the power output of the gas turbine, the exhaust gas conditions and the plant configuration, while the installed cost is around twice that of a large centralized CCGT on a US$/kW basis. The drawback of a conventional combined cycle plant design is the need for water, which is a scarce commodity in some regions. Air cooling of the CCGT plant can be used to reduce water consumption, but make-up water will still be required for the steam system to compensate for steam losses, blowdown etc. While the lower exhaust gas temperatures of the smaller gas turbines impact the combined cycle efficiencies achievable, they do allow Organic Rankine Cycle (ORC) technology to be considered for an alternative combined cycle configuration. This paper compares both the capital and operating costs and performance of combined cycle power plants for distributed power applications in the 30MW to 250MW power range based on conventional steam and various different ORC configurations.

Inlet Air Cooling Methods for Gas Turbine Based Power Plants

2004 ◽  
Author(s):  
E. Kakaras ◽  
A. Doukelis ◽  
A. Prelipceanu ◽  
S. Karellas
Keyword(s):  
Gas Turbine ◽  
Power Output ◽  
Gas Turbines ◽  
Power Plants ◽  
Evaporative Cooling ◽  
Climatic Conditions ◽  
Combined Cycle ◽  
Air Cooling ◽  
Cooling Systems ◽  
Cooling Methods

Power generation from gas turbines is penalised by a substantial power output loss with increased ambient temperature. By cooling down the gas turbine intake air, the power output penalty can be mitigated. The purpose of this paper is to review the state of the art in applications for reducing the gas turbine intake air temperature and examine the merits from integration of the different air-cooling methods in gas turbine based power plants. Three different intake air-cooling methods (evaporative cooling, refrigeration cooling and evaporative cooling of pre-compressed air) have been applied in two combined cycle power plants and two gas turbine plants. The calculations were performed on a yearly basis of operation, taking into account the time-varying climatic conditions. The economics from integration of the different cooling systems were calculated and compared.

Advancements in H Class Gas Turbines and Combined Cycle Power Plants

2018 ◽  
Author(s):  
Christian Vandervort
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Operating Experience ◽  
Combined Cycle ◽  
Test Facility ◽  
Air Cooling ◽  
Operational Flexibility ◽  
Cycle Efficiency

The power generation industry is facing unprecedented challenges. High fuel costs combined with an increased penetration of renewable power has resulted in greater demand for high efficiency and operational flexibility. Imperative for a reduced carbon footprint places an even higher premium on efficiency. Power producers are seeking highly efficient, reliable, and operationally flexible solutions that provide long-term profitability in a volatile environment. New generation must also be cost-effective to ensure affordability for both domestic and industrial consumers. Gas turbine combined cycle power plants provide reliable, dispatch-able generation with low cost of electricity, reduced environmental impact, and improved flexibility. GE’s air-cooled, H-class gas turbines (7/9HA) are engineered to achieve greater than 63% net, combined cycle efficiency while delivering operational flexibility through deep, emission-compliant turndown and high ramp rates. The largest of these gas turbines, the 9HA.02, exceeds 64% combined cycle efficiency (net, ISO) in a 1 × 1, single-shaft configuration. In parallel, the power plant has been configured for rapid construction and commissioning enabling timely revenue generation for power plant developers and owners. The HA platform is enabled by 1) use of a simple air-cooling system for the turbine section that does not require external heat exchange and the associated cost and complexity, and 2) use of well-known materials and coatings with substantial operating experience at high firing temperatures. Key technology improvements for the HA’s include advanced cooling and sealing, utilization of unsteady aerodynamic methodologies, axially staged combustion and next generation thermal barrier coating (TBC). Validation of the architecture and technology insertion is performed in a dedicated test facility over the full operating range. As of February 2018, a total of 18 HA power plants have achieved COD (Commercial Operation). This paper will address three topics relating to the HA platform: 1) gas turbine product technology, 2) gas turbine validation and 3) integrated power plant commissioning and operating experience.

Effect of Inlet Air Cooling by Absorption Chiller on Gas Turbine and Combined Cycle Performance

2005 ◽  
Author(s):  
Hiwa Khaledi ◽  
Roozbeh Zomorodian ◽  
Mohammad Bagher Ghofrani
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Cooling System ◽  
Positive Influence ◽  
Combined Cycle ◽  
Cycle Performance ◽  
Air Cooling ◽  
Internal Source ◽  
Absorption Chiller

Gas turbine performances are directly related to site conditions. The use of gas turbines in combined gas-steam power plants, also applied to cogeneration, increases such dependence. In recent years, inlet air cooling systems have been introduced to control air temperature at compressor inlet, resulting in an increase in plant power and efficiency. In this paper, the dependence of outside conditions for a simple gas turbine and a combined cycle plant is studied, using absorption chiller as inlet air cooling system. We used, as case study, a simple plant equipped with one frame E gas turbine and a combined cycle with a two pressure level heat recovery steam generator (HRSG). It was found that inlet air cooling with absorption chiller has great positive influence on power and less on efficiency of the gas turbine plant. Two steam sources (External and Internal) have been considered for chiller. External source has large positive influence on power but keep the efficiency of the combined cycle unchanged, while internal source causes a reduction in steam turbine mass flow. Consequently power production and efficiency of the combined cycle decrease. This reduction is lower in mid temperature (25 to 35°C) but higher in high temperature (35 to 45°C). Inlet cooling would result in lowering turbine exhaust temperature, thus decreasing the efficiency of HRSG.

Performance Assessment of Steam Injection Gas Turbine With Inlet Air Cooling

1997 ◽  
Author(s):  
Carlo M. Bartolini ◽  
Danilo Salvi
Keyword(s):  
Ambient Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Power Plants ◽  
Waste Heat ◽  
Cooling System ◽  
Steam Injection ◽  
Maximum Efficiency ◽  
Air Cooling

The steam generated through the use of waste heat recovered from a steam injection gas turbine generally exceeds the maximum mass of steam which can be injected into steam injection gas turbine. The ratio between the steam and air flowing into the engine is not more than 10–15%, as an increase in the pressure ratio can cause the compressor to stall. Naturally, the surplus steam can be utilized for a variety of alternative applications. During the warmer months, the ambient temperature increases and results in reduced thermal efficiency and electrical capacity. An inlet air cooling system for the compressor on a steam injection gas turbine would increase the rating and efficiency of power plants which use this type of equipment. In order to improve the performance of steam injection gas turbines, the authors investigated the option of cooling the intake air to the compressor by harnessing the thermal energy not used to produce the maximum quantity of steam that can be injected into the engine. This alternative use of waste energy makes it possible to reach maximum efficiency in terms of waste recovery. This study examined absorption refrigeration technology, which is one of the various systems adopted to increase efficiency and power rating. The system itself consists of a steam injection gas turbine and a heat recovery and absorption unit, while a computer model was utilized to evaluate the off design performance of the system. The input data required for the model were the following: an operating point, the turbine and compressor curves, the heat recovery and chiller specifications. The performance of an Allison 501 KH steam injection gas plant was analyzed by taking into consideration representative ambient temperature and humidity ranges, the optimal location of the chiller in light of all the factors involved, and which of three possible air cooling systems was the most economically suitable. In order to verify the technical feasibility of the hypothetical model, an economic study was performed on the costs for upgrading the existing steam injection gas cogeneration unit. The results indicate that the estimated pay back period for the project would be four years. In light of these findings, there are clear technical advantages to using gas turbine cogeneration with absorption air cooling in terms of investment.

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