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.

scholarly journals Performance Analysis With Different Means of Cooling in a Combined Cycle

1995 ◽  
Author(s):  
Onkar Singh ◽  
R. Yadav
Keyword(s):  
Gas Turbine ◽  
Power Plants ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Optimum Pressure ◽  
Cooling Medium ◽  
Cooling Technology ◽  
Improved Performance ◽  
Topping Cycle

Combined cycle based power plants and their development and application for energy efficient base load power generation necessitates enforced cooling to maintain the topping cycle gas turbine blade temperature at permissible levels, attributed to the increased turbine inlet temperature and compressor pressure ratio, for the improved performance and reliability of combined cycle. The mathematical model based on expansion path inside gas turbine considering dilution of mainstream and aerodynamic mixing losses for a range of cooling medium has been developed based on internal, film, transpiration cooling technologies and a combination of these. It is found that the appreciation of a cycle configuration as well as the optimum pressure ratio and peak temperature vary significantly with types of cooling technology adopted. Steam cooling for rotor appears to be a very potential cooling medium, when employed with an appropriate cooling technology. This paper deals with the thermodynamic analysis of turbine cooling using, different means of cooling i.e. air, water and steam.

Effect of Bottoming Cycle Alternatives on the Performance of Combined Cycle

2003 ◽  
Author(s):  
R. Yadav
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Positive Influence ◽  
Combined Cycle ◽  
Exhaust Temperature ◽  
Compressor Pressure Ratio ◽  
Topping Cycle ◽  
Steam Parameters ◽  
Cycle Efficiency ◽  
Steam Cycle

The increase in efficiency of combined cycle has mainly been caused by the improvements in gas turbine cycle efficiency. With the increase in firing temperature the exhaust temperature is substantially high around 873 K for moderate compressor pressure ratio, which has positive influence on steam cycle efficiency. Minimizing the irreversibility within the heat recovery steam generator HRSG and choosing proper steam cycle configuration with optimized steam parameters improve the steam cycle efficiency and thus in turn the combined cycle efficiency. In this paper, LM9001H gas turbine, a state of art technology turbine with modified compressor pressure ratio has been chosen as a topping cycle. Various bottoming cycles alternatives (sub-critical) coupled with LM9001H topping cycle with and without recuperation such as dual and triple pressure steam cycles with and without reheat have been chosen to predict the performance of combined cycle.

An Integrated Steam/Gas Turbine-Generator for Combined-Cycle Applications

1989 ◽  
Author(s):  
J. H. Moore
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Power Plants ◽  
Combined Cycle ◽  
Gas Temperature ◽  
Turbine Generator ◽  
Fully Integrated ◽  
Reheat Steam ◽  
Exhaust Gas Temperature ◽  
Steam Cycle

Combined-cycle power plants have been built with the gas turbine, steam turbine, and generator connected end-to-end to form a machine having a single shaft. To date, these plants have utilized a nonreheat steam cycle and a single-casing steam turbine of conventional design, connected to the collector end of the generator through a flexible shaft coupling. A new design has been developed for application of an advanced gas turbine of higher rating and higher firing temperature and exhaust gas temperature with a reheat steam cycle. The gas turbine and steam turbine are fully integrated mechanically, with solid shaft couplings and a common thrust bearing. This paper describes the new machine, with emphasis on the steam turbine section where the elimination of the flexible coupling created a number of unusual design requirements. Significant benefits in reduced cost and reduced complexity of design, operation, and maintenance are achieved as a result of the integration of the machine and its control and auxiliary systems.

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.

Technology Development Programs for the Advanced Turbine Systems Engine

1996 ◽  
Author(s):  
Ihor S. Diakunchak ◽  
Ronald L. Bannister ◽  
David J. Huber ◽  
D. Frank Roan
Keyword(s):  
Closed Loop ◽  
Technology Development ◽  
Combined Cycle ◽  
Advanced Materials ◽  
Development Programs ◽  
Turbine Engine ◽  
Design Concepts ◽  
Current State ◽  
Low Nox Combustion ◽  
Steam Cooling

This paper describes the technologies that are being developed or extended beyond the current state-of-the-art to achieve Advanced Turbine Systems (ATS) Program goals. The Westinghouse ATS plant is an advanced closed-loop enoled combined cycle, based on an advanced gas turbine engine incorporating novel design concepts and enhancements of existing technologies. The ATS engine is a fuel-flexible design operating nn natural gas with provisions fnr future conversion to coal or biomass fuels. It is based nn proven concepts employed in 501F and 501G engines. To achieve the required performance and reliability the engine will include closed-loop steam cooling, advanced materials and coatings, and enhanced component performance. To minimize NOx emissions, an ultra-low NOx combustion system will be incorporated. To ensure technical success, development programs are being conducted on the following: closed-loop steam cooling, advanced materials and coatings, component aerodynamic performance, flow visualization, optical diagnostics, combustion generated noise, and catalytic combustion.

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.

Parametric study on the performance of combined power plant of steam and gas turbines

2021 ◽  
pp. 1-18
Author(s):  
Mohammad Almajali ◽  
Omar Quran
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Parametric Study ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Design Parameters ◽  
Pressure Steam ◽  
Reheat Steam ◽  
Steam Cycle

Abstract This paper deals with aspects of the combined power and power (CPP) plants. Such plants consist of two major parts; the steam turbine and gas turbine plants. This study investigates the efficiency of CPP under the effect of several factors. CPP plants can achieve the highest thermal efficiency obtained with turbomachinery up to date. In this cycle, the anticipated waste thermal energy of the exhaust of gas turbine is used to generate a high pressure steam to empower the steam turbine in the steam cycle. By systematically varying the main design parameters, their influence on the CPP plant can be revealed. A comprehensive parametric study was conducted to measure the influence of the main parameter of the gas and steam cycles on the performance of CPP. The results exhibit that the overall plant thermal efficiency is significantly greater than that of either the two turbines. Due to the high thermal efficiency, a significant reduction in the greenhouse effect can be achieved. It is found that regenerative steam cycle will reduce the overall efficiency of combined cycle. On the other hand, using reheat steam cycle in the CPP plant will lead to an increase in both the thermal efficiency of the plant and the dryness factor of steam at exit of the steam turbine.

Efficiency Entitlement for Bottoming Cycles

2006 ◽  
Author(s):  
Douglas C. Hofer ◽  
S. Can Gulen
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Combined Cycle ◽  
New Method ◽  
Working Fluid ◽  
Generating Capacity ◽  
Topping Cycle ◽  
Cycle Efficiency ◽  
Steam Cycle

A significant portion of the new electrical generating capacity installed in the past decade has employed heavy-duty gas turbines operating in a combined cycle configuration with a steam turbine bottoming cycle. In these power plants approximately 1/3 of the power is generated by the bottoming cycle. To ensure that the highest possible combined cycle efficiency is realized it is important to optimize the bottoming cycle efficiency and doing so requires a solid understanding of the efficiency entitlement. This paper describes a new technique for calculating the theoretical efficiency entitlement for a bottoming cycle that corresponds to the maximum possible bottoming cycle work and maximized combined cycle work and efficiency. This new method accounts for the decrease in ideal efficiency as the gas turbine exhaust is cooled as it transfers heat energy to the working fluid in the bottoming cycle. The new definition is compared to conventional definitions, including that of Carnot and an Exergy based second law efficiency, and shown to provide a simple and accurate analytical expression for the entitlement efficiency in a bottoming cycle. For representative cycle conditions, the entitlement efficiency for the bottoming cycle is calculated to be ∼45% compared to the Carnot efficiency for the same conditions of ∼67%. Although the new method is applicable to any power cycle obtaining its heat input from the exhaust stream of a topping cycle, special attention is given to the steam bottoming cycle traditionally used in modern gas turbine combined cycle power plants. Comparisons are made between the ideal bottoming cycle and variants of a steam cycle including a single pressure non-reheat and a three pressure reheat cycle. These comparisons explore the unavoidable loss in efficiency associated with constant temperature heat addition that occurs in the steam cycle.

Thermodynamic Evaluation of Advanced Combined Cycle Using Latest Gas Turbine

2003 ◽  
Author(s):  
Sanjay ◽  
Onkar Singh ◽  
B. N. Prasad
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Specific Work ◽  
Thermodynamic Evaluation ◽  
Compressor Pressure Ratio ◽  
Steam Cooling ◽  
Plant Efficiency

The present work deals with the thermodynamic evaluation of combined cycle with re-heat in gas turbine using the latest gas turbines namely ABB GT26 gas turbine (advanced) in which reheat is used and the blade cooling is done by air bled from compressor. The same turbine is subjected to closed loop steam cooling. Parametric study has been performed on plant efficiency and specific work for various independent parameters such as turbine inlet temperature, compressor pressure ratio, reheating pressure ratio, reheater inlet temperature, blade temperature, etc.. It has been observed that due to higher compressor pressure ratio involved in reheat gas turbine combined cycle and higher temperature of exhaust, the plant efficiency and specific work are higher with the advanced reheat gas/steam combined cycle over the simple combined cycle. Steam cooling offers better performance over aircooling.

scholarly journals Numerical Investigation of a Radially Cooled Turbine Guide Vane Using Air and Steam as a Cooling Medium

Computation ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 63
Author(s):  
Sondre Norheim ◽  
Shokri Amzin
Keyword(s):  
Numerical Model ◽  
Gas Turbines ◽  
Guide Vane ◽  
Axial Direction ◽  
Average Error ◽  
Inlet Temperature ◽  
Average Temperature ◽  
Cooling Medium ◽  
Turbine Guide Vane ◽  
Steam Cooling

Gas turbine performance is closely linked to the turbine inlet temperature, which is limited by the turbine guide vanes ability to withstand the massive thermal loads. Thus, steam cooling has been introduced as an advanced cooling technology to improve the efficiency of modern high-temperature gas turbines. This study compares the cooling performance of compressed air and steam in the renowned radially cooled NASA C3X turbine guide vane, using a numerical model. The conjugate heat transfer (CHT) model is based on the RANS-method, where the shear stress transport (SST) k−ω model is selected to predict the effects of turbulence. The numerical model is validated against experimental pressure and temperature distributions at the external surface of the vane. The results are in good agreement with the experimental data, with an average error of 1.39% and 3.78%, respectively. By comparing the two coolants, steam is confirmed as the superior cooling medium. The disparity between the coolants increases along the axial direction of the vane, and the total volume average temperature difference is 30 K. Further investigations are recommended to deal with the local hot-spots located near the leading- and trailing edge of the vane.

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