Development of Ni-Base Disk Alloy for Large-Size Gas Turbines by Improving Macrosegregation Property of Alloy 718

2018 ◽  
pp. 1087-1101
Author(s):  
T. Shibayama ◽  
J. Sato ◽  
N. Sato ◽  
T. Nonomura ◽  
E. Shimohira ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Alloy 718 ◽  
Large Size ◽  
Disk Alloy

A Thermoeconomic Comparison Between SOFC Hybrid Systems and the Most Worldwide Used Technologies Towards Competitive Innovative Plants

2009 ◽  
Author(s):  
A. Franzoni ◽  
L. Magistri ◽  
O. Tarnowsky ◽  
A. F. Massardo
Keyword(s):  
Power Generation ◽  
Power Plant ◽  
Hybrid Systems ◽  
Hybrid System ◽  
Gas Turbines ◽  
Point Of View ◽  
Thermodynamic Efficiency ◽  
Economic Point ◽  
Capital Costs ◽  
Large Size

This paper investigates options for highly efficient SOFC hybrid systems of different sizes. For this purpose different models of pressurised SOFC hybrids systems have been developed in the framework of the European Project “LARGE SOFC - Towards a Large SOFC Power Plant”. This project, coordinated by VTT Finland, counts numerous industrial partners such as Wartsila, Topsoe and Rolls-Royce FCS ltd. Starting from the RRFCS Hybrid System [1], considered as the reference case, several plant modifications have been investigated in order to improve the thermodynamic efficiency. The main options considered are (i) the integration of a recuperated micro gas turbine and (ii) the replacement of the cathodic ejector with a blower. The plant layouts are analysed in order to define the optimum solution in terms of operating parameters and thermodynamic performances. The study of a large size power plant (around 110 MWe) fed by coal and incorporated with SOFC hybrid systems is also conducted. The aim of this study is to analyse the sustainability of an Integrated Gasification Hybrid System from the thermodynamic and economic point of view in the frame of future large sized power generation. A complete thermoeconomic analysis of the most promising plants is carried out, taking into account variable and capital costs of the systems. The designed systems are compared from the thermodynamic and the thermoeconomic point of view with some of the common technologies used for distributed generation (gas turbines and reciprocating engines) and large size power generation (combined cycles and IGCC). The tool used for this analysis is WTEMP software, developed by the University of Genoa (DIMSET-TPG) [2], able to carry out a detailed thermodynamic and thermoeconomic analysis of the whole plants.

scholarly journals Effect of Inclusions on the Corrosion Properties of the Nickel-Based Alloys 718 and EP718

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1177 ◽  
Author(s):  
Ekaterina Alekseeva ◽  
Andrey Karasev ◽  
Pär G. Jönsson ◽  
Aleksey Alkhimenko
Keyword(s):  
Corrosion Resistance ◽  
Alloy 718 ◽  
Corrosion Properties ◽  
Electrolytic Extraction ◽  
Operational Conditions ◽  
Large Size ◽  
Size Number ◽  
Resistance To Deformation ◽  
The Given ◽  
Harmful Effects

Inclusions in steels and alloys are known to lower the resistance to deformation, as well as to lower the mechanical, corrosion and other properties. Studies of inclusions in nickel-based alloys are important since these materials could suffer from corrosion degradation in harsh operational conditions. This, in fact, could lead to a pitting initiation around the inclusions. Two industrial Ni-based alloys (alloy 718 and EP718) were investigated to determine the harmful effects of different inclusions on the corrosion resistance of Ni-based alloys. Specifically, the inclusion characteristics (such as composition, morphology, size, number and location) were determined for inclusions collected on film filters after electrolytic extraction and dissolution of a metal matrix around different inclusions on surfaces of metal samples after electrolytic extraction (EE). It was found that both Ni-based alloys contain various inclusion types: carbides (large size NbTi-C and small multicomponent carbides), nitrides TiNb-N and sulphides (TiNb-S in EP718 alloy). The most harmful effects on the corrosion resistance of metal were detected around sulphides and small carbides containing Mo, W, Cr. Dissolution effects were also observed around large carbides and nitrides, especially around inclusions larger than 10 µm. Moreover, the dissolution of a matrix around inclusions and clusters located on the grain boundaries were found to be 2.1–2.7 times larger compared to inclusions found inside of grains of the given alloy samples.

Micro Humid Air Cycle: Part B — Thermoeconomic Analysis

2003 ◽  
Author(s):  
J. Parente ◽  
A. Traverso ◽  
A. F. Massardo
Keyword(s):  
Gas Turbines ◽  
Electrical Power ◽  
Specific Work ◽  
Operational Flexibility ◽  
Humid Air ◽  
Capital Costs ◽  
Large Size ◽  
Heat Demand ◽  
Short Period ◽  
Specific Capital

Part A of this paper demonstrated that the HAT cycle, when applied to small-size gas turbines, can significantly enhance the efficiency and specific work of simple and recuperated cycles without the drastic changes to plant layout necessary in medium- and large-size plants. In this part B a complete thermoeconomic analysis is performed for microturbines operating in a Humid Air cycle. The capital cost and internal rate of return for both new machines and existing microturbines working in an mHAT-optimised cycle are presented and analysed. Three different scenarios are considered. The first scenario reflects a distributed electrical power generation application where cogeneration is not taken into account. Instead, the other two scenarios deal with CHP civil applications for different heat demands. The thermoeconomic results of the integrated mHAT cycle, based on a preliminary design of the saturator, demonstrate that microturbine performance can be greatly enhanced, while specific capital costs, in some cases, can be reduced up to 14%, without significant increase in layout complexity. Moreover, thanks to its operational flexibility (able to operate in dry and wet cycles), the mHAT is financially attractive for distributed power and heat generation (micro-cogeneration), particularly when heat demand is commutated in short period.

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 Model for the Simulation of Large-Size Single-Shaft Gas Turbine Start-Up Based on Operating Data Fitting

2007 ◽  
Author(s):  
Mirko Morini ◽  
Giovanni Cataldi ◽  
Michele Pinelli ◽  
Mauro Venturini
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Thermal Stresses ◽  
Simulated Data ◽  
Data Fitting ◽  
Turbine Engine ◽  
Operating Data ◽  
Large Size ◽  
Start Up ◽  
Thermal Status

Start-up is an important aspect of gas turbine operation. In the last years plant operators have shown an ever increasing interest in this critical phase, with particular focus on start-up reliability and start-up time. Several issues should be considered in order to achieve optimal start-up behavior: operability issues (e.g. compressor aerodynamics, combustor light-off and light-around, shaft acceleration), impact of thermal stresses on cyclic life, proper sizing of external starting devices. Models for the simulation of gas turbine behavior during start-up are very useful both for the design of new gas turbines and for the analysis and improvement of engines already in operation. In this paper, a physics-based model for the simulation of the start-up phase of large-size single-shaft gas turbines is presented. The model is based on operating data fitting and covers machine operation from combustor light-off to compressor blow off valve closure. The model makes use of steady-state component characteristics, while dynamics is taken into account through shaft power balance. Special features are also included to properly model the effects of heat soakage, i.e. the dependence of the engine behavior on its thermal status before the start-up. The quality of the model has been proven by application to the gas turbine engine ALSTOM GT13E2 and by comparison between measured and simulated data.

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.

scholarly journals Crack Growth Studies in a Welded Ni-Base Superalloy

2016 ◽  
Vol 258 ◽  
pp. 237-240
Author(s):  
Anand Harihara Subramonia Iyer ◽  
Krystyna Stiller ◽  
Magnus Hörnqvist Colliander
Keyword(s):  
Gas Turbines ◽  
High Strength ◽  
Fatigue Loading ◽  
Main Body ◽  
Alloy 718 ◽  
Jet Engines ◽  
Fine Grained ◽  
Dwell Fatigue ◽  
Corrosion Resistant Alloy

It is well known that the introduction of sustained tensile loads during high-temperature fatigue (dwell-fatigue) significantly increases the crack propagation rates in many superalloys. One such superalloy is the Ni-Fe based Alloy 718, which is a high-strength corrosion resistant alloy used in gas turbines and jet engines. As the problem is typically more pronounced in fine-grained materials, the main body of existing literature is devoted to the characterization of sheets or forgings of Alloy 718. However, as welded components are being used in increasingly demanding applications, there is a need to understand the behavior. The present study is focused on the interaction of the propagating crack with the complex microstructure in Alloy 718 weld metal during cyclic and dwell-fatigue loading at 550 °C and 650 °C.

Application of Latest Gas Turbine Technologies and Verification Results

2016 ◽  
Author(s):  
Yoshiaki Nishimura ◽  
Tomoyuki Sugawara ◽  
Kazuyuki Tada ◽  
Junichiro Masada ◽  
Toshishige Ai ◽  
...  
Keyword(s):  
Power Plant ◽  
Power Systems ◽  
Electric Power ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Fossil Fuel ◽  
Combined Cycle ◽  
Large Size ◽  
Fossil Fuel Consumption ◽  
Utility Companies

Utility companies and gas turbine manufacturer alike are working diligently to improve Gas Turbine Combined Cycle (GTCC) efficiency in order to reduce fossil fuel consumption as well as CO2 emissions. Tohoku Electric Power Co., Inc. started operating large size GTCC in 1984 with Mitsubishi D series gas turbines. Since then, the company has lead the application of first of class Mitsubishi gas turbines. The company applied the first M701G gas turbine in 1999 and this successful experience was followed in 2010 with the single-shaft Sendai GTCC featuring the first M701F4. The M701F5 was introduced in 2011 by Mitsubishi Hitachi Power Systems, LTD. (MHPS) and Tohoku Electric pioneered one more time its application at the No.3 Shin-Sendai Power Plant in 2015. The M701F5 features the combination of technologies verified in other gas turbine frames. This paper introduces the feature of the M701F5 gas turbine including its technologies and verification results.

High Temperature Strength of Large Size SC and DS Buckets for Industrial Gas Turbines

1995 ◽  
Author(s):  
M. Sato ◽  
Y. Kobayashi ◽  
H. Matsuzaki ◽  
H. Tamaki ◽  
A. Yoshinari ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Rupture Strength ◽  
Low Cycle Fatigue ◽  
Creep Rupture ◽  
High Temperature Strength ◽  
Cycle Fatigue ◽  
Creep Rupture Strength ◽  
Directionally Solidified ◽  
Large Size ◽  
Industrial Gas Turbines

This paper describes successful results of trial manufacturing of single crystal (SC) buckets, 235mm long, for industrial gas turbines. The bypass method was adopted for casting of the SC buckets. Directionally solidified (DS) buckets, whose size is the same as SC buckets, were cast without grain boundary cracking. The materials for the buckets are CMSX-4 for the SC buckets and CM186LC for the DS buckets. Applicability of these buckets was mainly evaluated by creep rupture tests. The degradation due to casting defects is negligible for both SC and DS buckets which achieve the aimed creep rupture strength for the 1500°C class industrial gas turbines, because these creep rupture strengths are similar to the cast to size (CTS) specimens. The other properties such as tensile strength, hot corrosion resistance, oxidation resistance and low cycle fatigue (LCF) were also obtained from the CTS specimens.

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