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.

Assessing Performance Degradation in Gas Turbines for Power Applications: A Challenging Task

2007 ◽  
Author(s):  
Justin Zachary
Keyword(s):  
Gas Turbines ◽  
Power Plants ◽  
Heat Rate ◽  
Degradation Process ◽  
Performance Degradation ◽  
Combined Cycle ◽  
Bench Mark ◽  
Fuel Quality ◽  
Actual Measurement ◽  
The Impact

The degradation of thermal performance is playing a significant role in the economic viability of the highly competitive merchant power plants. Since most of the gas turbines are used in Combined Cycles applications, the degradation is applicable not only to the traditional performance guaranteed values of power output and heat rate but also to exhaust flow and exhaust temperature. While the performance degradation of turbo machinery has been a widely accepted fact, an accurate quantitative assessment of the phenomenon is extremely difficult and costly. The paper will review the potential causes of degradation, related to variability in the manufacturing of the equipment, site configuration, fuel composition quality, operational requirements and maintenance practices. The article will also address the impact on the performance guarantees, due to qualifications applied to degradation process terms such as “new and clean condition”, “fired and equivalent operating hours”, and “bench mark testing”. In a combined cycle configuration, due to lengthy commissioning activities of various systems, acceptance performance tests are conducted only after a significant number of hours in operation have been accumulated. The article will discuss the viability and merits of conducting comparative testing during this commissioning period, aimed at the actual measurement of short-term deterioration. The potential obstacles and challenges of this testing program, associated with changes in the control system, hardware modifications and measurement uncertainty, will also be analyzed in details. The alternative option to account for the expected degradation is the use of correction curves supplied by the equipment manufacturers. The paper will review the suitability to specific project conditions of generically developed curves. In addition, the document will touch on how degradation evaluation may affect the Long Term Service Agreements (LTSA) between Owners and Equipment Manufacturers. Finally, the article will offer suggestions on how performance and fuel quality continuous monitoring, careful operations and maintenance scheduling could reduce the actual degradation and provide a substantial economic benefit to the Owner.

Conjugate Simulation of the Effects of Oxide Formation in Effusion Cooling Holes on Cooling Effectiveness

2009 ◽  
Author(s):  
Dieter Bohn ◽  
Robert Krewinkel
Keyword(s):  
Gas Turbines ◽  
Power Plants ◽  
Gas Flow ◽  
Combined Cycle ◽  
Reference Case ◽  
Flow Area ◽  
Cooling Effectiveness ◽  
Hot Gas ◽  
Barrier Coating ◽  
Cooling Hole

Within Collaborative Research Center 561 “Thermally Highly Loaded, Porous and Cooled Multi-Layer Systems for Combined Cycle Power Plants” at RWTH Aachen University an effusion-cooled multi-layer plate configuration with seven staggered effusion cooling holes is investigated numerically by application of a 3-D in-house fluid flow and heat transfer solver, CHTflow. The effusion-cooling is realized by finest drilled holes with a diameter of 0.2 mm that are shaped in the region of the thermal barrier coating. Oxidation studies within SFB 561 have shown that a corrosion layer of several oxides with a thickness of appoximately 20μm grows from the CMSX-4 substrate into the cooling hole. The goal of this work is to investigate the effect this has on the cooling effectiveness, which has to be quantified prior to application of this novel cooling technology in real gas turbines. In order to do this, the influence on the aerodynamics of the flow in the hole, on the hot gas flow and the cooling effectiveness on the surface and in the substrate layer are discussed. The adverse effects of corrosion on the mechanical strength are not a part of this study. A hot gas Mach-number of 0.25 and blowing ratios of approximately 0.28 and 0.48 are considered. The numerical grid contains the coolant supply (plenum), the solid body for the conjugate calculations and the main flow area on the plate. It is shown that the oxidation layer does significantly affect the flow field in the cooling holes and on the plate, but the cooling effectiveness differs only slightly from the reference case. This seems to justify modelling the holes without taking account of the oxidation.

Study of the Influence of the Nominal Power on the Selection of the CCGT Power Plant Optimum Configuration Including Supercritical Configurations

2008 ◽  
Author(s):  
M. D. Duran ◽  
A. Rovira
Keyword(s):  
Power Plant ◽  
Gas Turbines ◽  
Power Plants ◽  
Optimization Technique ◽  
Combined Cycle ◽  
Specific Power ◽  
Design Parameters ◽  
Plant Design ◽  
Economic Optimization ◽  
Optimum Configuration

It is the purpose of this work to show how to select the best configuration as a function of the combined cycle power. It uses thermo-economic optimization technique based on flexible genetic algorithms (GA). These results will be based on a Thermoeconomic model developed in previous works, this maximizes the cash flow by choosing the correct parameters for the plant design — particularly those corresponding to the HRSG — subject to the restriction that hypothetical, but realistic turbines have already been chosen. This study begins with an analysis of the trends in the commercial gas turbines (GT) design. It was observed that in spite of the diverse companies, the design parameters as well as the turbine cost, follow certain trends depending on the turbine power. When a CCGT power plant is planned, once the GT is selected, is necessary to determine which configuration of the HRSG is the most appropriate in order to get the maximum performance and the best economical results. There is a wide variety of selections of CCGT power plants configurations. To facilitate the analysis of this ample number of CCGT systems we will apply our study to the following types of HRSG: Double pressure with and without reheater, Triple pressure levels with reheater and Triple pressure levels with reheater and supercritical pressure. As a result of this study it may be observed that some design trends should be established so as to decide which configuration (including supercritical cycles) is better to select to specific power.

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.

Influence of Working Fluid on Gas Turbine Cooling Modeling

2013 ◽  
Author(s):  
Majed Sammak ◽  
Marcus Thern ◽  
Magnus Genrup
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Gas Turbines ◽  
Specific Power ◽  
Working Fluid ◽  
Cooling Effectiveness ◽  
Fuel Gas ◽  
Turbine Cooling ◽  
Blade Cooling ◽  
Turbine Inlet

Cooling is essential in all modern high-temperature gas turbines. Turbine cooling is mainly a function of gas entry temperature, which plays the key role in overall gas turbine performance. High turbine entry temperatures can be achieved through appropriate selection of blade cooling method and blade material. The semi-closed oxy-fuel combustion combined cycle (SCOC-CC) operates at the same high entry gas temperature, hence blade cooling is necessary. The aim of this paper was to calculate the required turbine cooling in oxy-fuel gas turbines and compare it to the required turbine cooling in conventional gas turbines. The approach of the paper was to evaluate the thermodynamic and aerodynamic factors affecting turbine cooling with using the m*-model. The results presented in the paper concerned a single turbine stage at a reference diameter. The study showed greater cooling effectiveness in conventional gas turbines, but a greater total cooled area in oxy-fuel gas turbines. Consequently, the calculated total required cooling mass flow was close in the both single stage turbines. The cooling requirement and cooled area for a conventional and oxy-fuel twin-shaft gas turbine was also examined. The gas turbine was designed with five turbine stages. The analysis involved various turbine power and combustion outlet temperatures (COT). The results showed that the total required cooling mass flow was proportional to turbine power because of increasing gas turbine inlet mass flow. The required cooling mass flow was proportional to COT as the blade metal temperature is maintained at acceptable limit. The analysis revealed that required cooling for oxy-fuel gas turbines was higher than for conventional gas turbines at a specific power or specific COT. This is due to the greater cooled area in oxy-fuel gas turbines. The cooling effectiveness of conventional gas turbines was greater, which indicated higher required cooling. However, the difference in cooling effectiveness between conventional and oxy-fuel gas turbines was less in rear stages. The cooling mass flow as percentage of gas turbine inlet mass was slightly higher in conventional gas turbines than in oxy-fuel gas turbines. The required cooling per square meter of cooled area was used as a parameter to compare the required cooling for oxy-fuel and conventional gas turbines. The study showed that the required cooling per cooled area was close in both studied turbines.

New Developments in High Temperature Materials 21 Project in Japan

2005 ◽  
Author(s):  
Hiroshi Harada ◽  
Junzo Fujioka
Keyword(s):  
High Temperature ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Power Plants ◽  
Turbine Blades ◽  
Combined Cycle ◽  
Jet Engines ◽  
High Temperature Materials ◽  
Design Program ◽  
Temperature Capability

Following the Kyoto Conference on Climate Change (COP3) held in 1997, the improvement of thermal efficiency in power engineering systems is becoming a major issue. In High Temperature Materials 21 Project at NIMS, materials for turbine blades and vanes are being developed to improve the temperature capability and reduce the CO2 emission of industrial gas turbines (IGT) and jet engines. The target for Ni-base superalloys was set at 1100°C for 1000h creep rupture life under 137MPa to realize ultra-efficient combined cycle power plants and advanced jet engines. A high cost-performance single crystal (SC) superalloy TMS-82+ with 1075°C temperature capability has been developed and tested in a 15MW IGT. A 4th generation SC superalloy TMS-138 exhibiting 1080°C temperature capability has also been developed and tested in a 1650°C test jet engine. TMS-138 is to be applied in the Japanese eco-engine project for 50-seater jet airplanes. A further control of the interfacial dislocation network resulted in a 5th generation SC alloy TMS-162 with 1105°C temperature capability. A virtual gas turbine (VT), which is a combination of materials design program and system design program, is being developed and becoming a powerful tool as an interface between material scientists and system engineers. Using VT, air-cooled blades with our SC superalloys have been evaluated up to 1700°C gas temperature, and a substantial improvement in thermal efficiency of a combined-cycle power generation system has been indicated.

scholarly journals Transpiration Air Protected Turbine Blades: An Effective Concept to Achieve High Temperature and Erosion Resistance for Gas Turbines Operating in an Aggressive Environment

1978 ◽  
Author(s):  
R. Raj ◽  
S. L. Moskowitz
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Erosion Resistance ◽  
Turbine Blades ◽  
Future Generation ◽  
Combined Cycle ◽  
Gaseous Fuels ◽  
Cooled Blade

The future generation is looking forward to the use of gas turbine inlet temperatures as high as 3000 F (1650 C) with attendant thermal efficiencies of from 40 to 50 percent in combined cycle electric power plants. In addition to the use of high temperature for improved efficiency, the national needs, due to scarcity of oil and natural gas, will heavily stress the use of coal as a fuel. The particulate from combustion of coal derived liquid and gaseous fuels, even after employing hot gas cleanup systems, may damage conventional turbine blades and thus reduce turbine life. This paper is intended to show how a transpiration-cooled blade can cope with both of the foregoing problems simultaneously. The fundamental aspects of the transpiration-cooled blade technology will also be explained. Experimental results using this design concept indicate that significant erosion resistance is feasible for gas turbine blading in the near future.

Evaluating Performance Degradation in Gas Turbines: A Challenging Task

2005 ◽  
Author(s):  
Justin Zachary
Keyword(s):  
Gas Turbines ◽  
Heat Rate ◽  
Degradation Process ◽  
Performance Degradation ◽  
Combined Cycle ◽  
Bench Mark ◽  
Fuel Quality ◽  
Actual Measurement ◽  
Exhaust Temperature ◽  
The Impact

The degradation of thermal performance plays a significant role in the economic viability a combined cycle plant. The degradation is applicable not only to the performance guaranteed values for power output and heat rate but also to exhaust flow and exhaust temperature. While the performance degradation of turbo machinery has been a widely accepted fact, an accurate quantitative assessment of the phenomenon is extremely difficult and costly. The paper will review the potential causes of degradation, related to variability in the manufacturing of the equipment, site configuration, fuel composition quality, operational requirements and maintenance practices. The article will also address the impact on the performance guarantees, due to qualifications applied to degradation process terms such as “new and clean condition”, “fired and equivalent operating hours”, and “bench mark testing”. In a combined cycle configuration, due to lengthy commissioning activities of various systems, the acceptance performance tests are conducted only after a significant number of hours in operation have been accumulated. The article will discuss the viability and merits of conducting comparative testing during this commissioning period, aimed at the actual measurement of short-term deterioration. The potential obstacles and challenges of this testing program, associated with changes in the control system, hardware modifications and measurement uncertainty, will also be analyzed in details. The alternative option to account for the expected degradation is the use of correction curves supplied by the equipment manufacturers. The paper will review the suitability to specific project conditions of generically developed curves. In addition, the document will touch on how degradation evaluation may affect the Long Term Service Agreements (LTSA) between Owners and Equipment Manufacturers. Finally, the paper will offer suggestions on how performance and fuel quality continuous monitoring, careful operations and maintenance scheduling could reduce the actual degradation and provide a substantial economic benefit to the Owner.

scholarly journals Compressor Retrofittable Solutions in Heavy-Duty Gas Turbines for Minimum Environmental Load Reduction

2019 ◽  
Vol 113 ◽  
pp. 01012
Author(s):  
Stefano Gino Mosele ◽  
Tiziano Garbarino ◽  
Andrea Schneider ◽  
Lorenzo Cozzi ◽  
Andrea Arnone ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Power Plants ◽  
Stability Margin ◽  
Combined Cycle ◽  
Environmental Load ◽  
Cfd Modelling ◽  
International Policies ◽  
Starting Point ◽  
Compressor Performance ◽  
The Impact

International policies aiming at keeping global warming within safety limits will strongly impact gas-fired power plants. Flexibility is going to be the key-word, hence this paper focuses on possible strategies to increase turndown capability (i.e. lowering Minimum Environmental Load (MEL)) of open and combined cycle power plants (CCPP) through retrofittable compressor service packages. In particular, the following three options have been analyzed: extra-closure of Variable Inlet Guide Vanes (IGVs), Blow-Off (BO) lines opening and inlet bleed heating. All these solutions aim at reducing the compressor outlet mass-flow rate while keeping a safe stability margin. The effect of lowering the minimum load capability by opening the BO lines has been numerically investigated through full compressor 2D throughflow analyses. Moreover, the impact on compressor performance and stability of the extra-closure of IGVs has been analyzed with the support of 3D steady-state CFD modelling. Finally, the overall performance of the power-plant has been included and discussed in order to provide plant managers with a solid starting point for a techno-economic analysis.

Design and Operational Aspects of Gas and Steam Turbines for the Novel Solar Hybrid Combined Cycle SHCC®

2010 ◽  
Author(s):  
Stephan Heide ◽  
Uwe Gampe ◽  
Ulrich Orth ◽  
Markus Beukenberg ◽  
Bernd Gericke ◽  
...  
Keyword(s):  
High Temperature ◽  
Power Plant ◽  
Gas Turbine ◽  
Heat Input ◽  
Gas Turbines ◽  
Power Plants ◽  
Combined Cycle ◽  
Solar Irradiation ◽  
Test Field ◽  
Solar Heat

Solar hybrid power plants are characterized by a combination of heat input both of high temperature solar heat and heat from combustion of gaseous or liquid fuel which enables to supply the electricity market according to its requirements and to utilize the limited and high grade natural resources economically. The SHCC® power plant concept integrates the high temperature solar heat into the gas turbine process and in addition — depending on the scheme of the process cycle — downstream into the steam cycle. The feed-in of solar heat into the gas turbine is carried out between compressor outlet and combustor inlet either by direct solar thermal heating of the pressurized air inside the receivers of the solar tower or by indirectly heating via interconnection of a heat transfer fluid. Thus, high shares of solar heat input referring to the total heat input of more than 60% in design point can be achieved. Besides low consumption of fossil fuels and high efficiency, the SHCC® concept is aimed for a permanent availability of the power plant capacity due to the possible substitution of solar heat by combustion heat during periods without sufficient solar irradiation. In consequence, no additional standby capacity is necessary. SHCC® can be conducted with today’s power plant and solar technology. One of the possible variants has already been demonstrated in the test field PSA in Spain using a small capacity gas turbine with location in the head of the solar tower for direct heating of the combustion air. However, the authors present and analyze also alternative concepts for power plants of higher capacity. Of course, the gas turbine needs a design which enables the external heating of the combustion air. Today only a few types of gas turbines are available for SHCC® demonstration. But these gas turbines were not designed for solar hybrid application at all. Thus, the autors present finally some reflections on gas turbine parameters and their consequences for SHCC® as basis for evaluation of potentials of SHCC®.

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