Thermodynamic Analysis of Closed Loop Cooled Cycles

1997 ◽  
Author(s):  
Darren T. Watson ◽  
Ian Ritchey
Keyword(s):  
Gas Turbines ◽  
Closed Loop ◽  
Cooling System ◽  
Open Loop ◽  
Combined Cycle ◽  
Relative Advantage ◽  
Specific Power ◽  
Efficiency Gain ◽  
Steam Cooling ◽  
Practical Constraints

Closed loop steam cooling schemes have been proposed by a number of manufacturers for advanced Combined Cycle Gas Turbine (CCGT) power plant (see for example Corman (1996) and Briesch et al. (1994)) asserting that thermal efficiencies in excess of 60% (LHV) are achievable combined with significant improvements of ∼15% in specific power (see Corman (1995)). In understanding the efficiency advantage however, the relative performance of each cooling system (subject to the same practical constraints and technology levels) is a better indicator then the absolute value. Assessment of the performance of such novel schemes generally involves a detailed numerical analysis of an integrated cycle which may often prevent validation of the results or obscure an understanding of the physical basis for the claimed improvements. Here, to overcome this, a group of simplified expressions are defined for the variation of each cycles efficiency due to cooling which show where the differences come from. These expressions are based simply on a calculation of the marginal increase in heat rejected, to the environment from the cycle, due to an increase in the level of cooling. After these relationships are validated using detailed heat balance calculations they are used to compare the main cooling options, namely open loop air, closed loop air and closed loop steam when subject to the same practical constraints and assumptions. Based on these results it is proposed that the relative advantage of closed loop cooling may not be as significant as previously thought. Furthermore, it is shown that the closed loop cooling efficiency gain is heavily dependent on the performance and reliability of substantial Thermal Barrier Coatings (TBCs). Finally, although the majority of recent interest in closed loop cooling schemes has focused upon CCGT plant, there are other systems where the benefits of closed loop steam cooling appear to be greater, in particular cycles involving steam injected gas turbines. Such a cycle is analysed here with a number of advanced cooling options.

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.

Evaluation of Advanced Combined Cycle Power Plants

1998 ◽  
Vol 212 (1) ◽  
pp. 1-12 ◽  
Author(s):  
C Kail
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Power Plants ◽  
Closed Loop ◽  
Cooling System ◽  
Turbine Blades ◽  
Combined Cycle ◽  
Steam Quality ◽  
Technical Problems ◽  
Steam Cooling

This report will analyse and evaluate the most recent and significant trends in combined cycle gas turbine (CCGT) power plant configurations. The various enhancements will be compared with the ‘simple’ gas turbine. The first trend, a gas turbine with reheat, cannot convert its better efficiency and higher output into a lower cost of electrical power. The additional investments required as well as increased maintenance costs will neutralize all the thermodynamic performance advantages. The second concept of cooling the turbine blades with steam puts very stringent requirements on the blade materials, the steam quality and the steam cooling system design. Closed-loop steam cooling of turbine blades offers cost advantages only if all its technical problems can be solved and the potential risks associated with the process can be eliminated through long demonstration programmes in the field. The third configuration, a gas turbine with a closed-loop combustion chamber cooling system, appears to be less problematic than the previous, steam-cooled turbine blades. In comparison with an open combustion chamber cooling system, this solution is more attractive due to better thermal performance and lower emissions. Either air or steam can be used as the cooling fluid.

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.

H System™ Technology Update

2003 ◽  
Author(s):  
John E. Pritchard
Keyword(s):  
Power Generation ◽  
Power Plant ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Closed Loop ◽  
Cooling System ◽  
Validation Process ◽  
Full Speed ◽  
Steam Cooling

Responding to a global market demand for clean, reliable and low-cost energy, GE Power Systems introduced its newest, most advanced generation of gas turbines in 1995. Called the H System™ this technology uses higher efficiency and output to produce electricity at lower costs than any other gas-fired power generation system available today. Efficiency. The H System™ is designed to achieve 60% thermal efficiency, a major milestone in the power generation industry. The most efficient combined-cycle systems currently in operation reach 57–58% efficiency. The use of advanced materials and a unique, steam-cooling system enable the higher firing temperatures required for this increase in efficiency. The integrated closed-loop steam cooling system uses steam from the steam turbine bottoming cycle to more efficiently cool the critical gas turbine parts, and returns the steam to the bottoming cycle where it can produce additional work in the steam turbine. Environmental Performance. The H System™ burns natural gas, a much cleaner fuel than other options such as oil or coal. In addition, the system’s higher efficiency means that less fuel is needed to produce the same amount of power, further reducing emissions of CO2 and NOx. The closed-loop steam cooling system cools both the rotating and stationary gas turbine parts to maintain combustion chamber exit temperatures for low NOx emissions, while permitting the high gas turbine firing temperatures required for increased efficiency and output. Reliability. The H System™ is based on technology proven in millions of hours of GE aircraft engine and power plant service. In particular, the lessons learned throughout the development and 7.1 million hours of worldwide operating experience of GE’s F technology have been applied to the H System™. Status. This technology has been subjected to an extensive validation process. This process includes component, scale, and full size rig testing, Full Speed No Load factory tests, and culminates in Full Speed Full Load characterization testing in a commercial power plant. This paper discusses the validation process and status for the 50 Hz S109H and 60 Hz S107H in more detail.

scholarly journals Closed Circuit Steam Cooling in Gas Turbines

1987 ◽  
Author(s):  
E. D. Alderson ◽  
G. W. Scheper ◽  
A. Cohn
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Closed Circuit ◽  
Cycle Performance ◽  
Specific Power ◽  
Design Parameters ◽  
Steam Cooling ◽  
Ultimate Efficiency ◽  
Cooling Function

In the continuing effort to achieve better specific power and higher cycle efficiencies, gas turbine designers have through the years sought higher and higher firing temperatures. A large part of this gain in firing temperatures has been achieved through cooling the turbine nozzles and buckets. In almost all cases the coolant, usually air, is discharged into the gas path after performing its cooling function. This approach entails the double penalties of causing mixing losses and of producing a dilution of the hot gas stream by admixture of the lower temperature coolant. This paper presents a new cooling concept, developed under a study contract for Electric Power Research Institute, wherein high pressure steam is used as the coolant in a closed circuit steam cooling (CCSC) system. This not only avoids the mixing and dilution losses in the gas turbine, but permits recovery of the heat picked up in the coolant by expansion in a steam turbine. With CCSC, Brayton-combined cycle thermal efficiencies of 54% are projected using current materials and technology. With development of specific technologies, an ultimate efficiency for the Brayton-combined cycle of 57% is foreseen. This paper also discusses the sensitivity of the cycle performance to the design parameters. Performance of this CCSC cycle is compared to that of an advanced air-cooled Brayton combined cycle.

Thermodynamic Evaluation of Combined Cycle Using Different Methods of Steam Cooling

2004 ◽  
Author(s):  
Sanjay ◽  
Onkar Singh ◽  
B. N. Prasad
Keyword(s):  
Closed Loop ◽  
Combined Cycle ◽  
Thermodynamic Evaluation ◽  
Real Situation ◽  
Cooling Medium ◽  
Reheat Steam ◽  
Steam Cooling ◽  
Topping Cycle ◽  
Cooling Methods ◽  
Steam Cycle

This paper deals with comparative study of the influence of different methods of steam cooling on the performance of simple combined gas/steam cycle plants. The topping cycle chosen is simple gas turbine while the bottoming cycle is a triple-pressure reheat steam cycle. Steam has been chosen as the cooling medium to be studied, as it is the most promising medium. All possible open and closed loop cooling with steam as the cooling medium have been considered. The prediction is based on the modeling of various elements of simple combined gas/steam cycle considering the real situation. The study shows that closed loop steam cooling is superior as compared to other steam cooling methods. However even though other two methods are slightly inferior technologically, but they do not suffer from the chances of problems of cogging of coolant holes if the steam is not ultra pure.

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

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

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

Conceptual Design for Medium Size Combined Cycle Plants Improved by Recent Research and Innovation

2000 ◽  
Author(s):  
H. Jericha ◽  
F. Neumayer
Keyword(s):  
Conceptual Design ◽  
Gas Turbines ◽  
Cooling System ◽  
Economic Value ◽  
District Heating ◽  
Combined Cycle ◽  
Medium Size ◽  
Research And Innovation ◽  
Combined Cycle Plant ◽  
Reheat Steam

A conceptual design study for a 120 MW combined cycle plant is presented here. Values of 60% thermal efficiency are at present the realm of very large gas turbines of most advanced design with power outputs of 300 to 500 MW. For industry and district heating plants it would be of most economic value to achieve similar thermal efficiencies in medium size gas turbines and combined cycle plants as they are being installed in Central European cogeneration and district heating plants. The authors propose by concerted application of recent research results to achieve this goal for medium size combined cycle plants. Design measures incorporated are transonic turbine stages, an innovative cooling system and a 600 degree reheat steam turbine.

Experience With a Fast Track Power Generation Project

2000 ◽  
Author(s):  
Albrecht H. Mayer ◽  
Noel W. Lively
Keyword(s):  
System Performance ◽  
Gas Turbines ◽  
Fast Track ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Combined Cycle ◽  
Plant Design ◽  
Engineering Construction ◽  
Reference Plant ◽  
Evaporative Cooling System

To meet peaking power demands the E.W. Brown Station, owned and operated by Kentucky Utilities Company, was extended by two GT24 gas turbines. The project had to meet a 9-month engineering, construction and commissioning schedule. The conceptual design is based on ABB ALSTOM POWER’S reference plant design for combined cycle application. It was adjusted to the requirements of a simple cycle operation. Special plant features such as evaporative cooling of the inlet air, system design of the evaporative cooling system, performance and experience will be discussed in detail. The plant has an aggressive running and starting reliability goal; the approach to meet the required plant reliability will be discussed below. The initial operational feedback will be addressed as well as an outlook on how to meet all project goals.

Development of Next Generation Gas Turbine Combined Cycle System

2016 ◽  
Author(s):  
Hiroyuki Yamazaki ◽  
Yoshiaki Nishimura ◽  
Masahiro Abe ◽  
Kazumasa Takata ◽  
Satoshi Hada ◽  
...  
Keyword(s):  
Power Plant ◽  
Gas Turbines ◽  
Power Plants ◽  
Cooling System ◽  
Combined Cycle ◽  
Air Cooling ◽  
Next Generation ◽  
Air Cooling System ◽  
Forced Air ◽  
Cooling Air

Tohoku Electric Power Company, Inc. (Tohoku-EPCO) has been adopting cutting-edge gas turbines for gas turbine combined cycle (GTCC) power plants to contribute for reduction of energy consumption, and making a continuous effort to study the next generation gas turbines to further improve GTCC power plants efficiency and flexibility. Tohoku-EPCO and Mitsubishi Hitachi Power Systems, Ltd (MHPS) developed “forced air cooling system” as a brand-new combustor cooling system for the next generation GTCC system in a collaborative project. The forced air cooling system can be applied to gas turbines with a turbine inlet temperature (TIT) of 1600deg.C or more by controlling the cooling air temperature and the amount of cooling air. Recently, the forced air cooling system verification test has been completed successfully at a demonstration power plant located within MHPS Takasago Works (T-point). Since the forced air cooling system has been verified, the 1650deg.C class next generation GTCC power plant with the forced air cooling system is now being developed. Final confirmation test of 1650deg.C class next generation GTCC system will be carried out in 2020.

Sign in / Sign up

Export Citation Format

Share Document