scholarly journals Practical aspects of material data bases and expert systems for high-temperature corrosion and coatings in gas turbines

1993 ◽  
Vol 03 (C9) ◽  
pp. C9-1001-C9-1012
Author(s):  
Henry L. Bernstein
Keyword(s):  
High Temperature ◽  
Expert Systems ◽  
Gas Turbines ◽  
High Temperature Corrosion ◽  
Data Bases ◽  
Material Data

Use of Chromium Containing Fuel Additive to Reduce High Temperature Corrosion of Hot Section Parts

2000 ◽  
Author(s):  
Jean-Pierre Stalder ◽  
Peter A. Huber
Keyword(s):  
High Temperature ◽  
Hot Corrosion ◽  
Gas Turbines ◽  
High Temperature Corrosion ◽  
Fuel Oil ◽  
Fuel Additive ◽  
Fuel Quality ◽  
Common Belief ◽  
Heavy Fuel Oil ◽  
Fuel Treatment

The use of “clean” fuel is a prerequisite at today’s elevated gas turbine firing temperature, modern engines are more sensitive to high temperature corrosion if there are impurities present in the fuel and/or in the combustion air. It is a common belief that distillate grade fuels are contaminant-free, which is often not true. Frequently operators burning distillates ignore the fuel quality as a possible source of difficulties. This matter being also of concern in plants mainly operated on natural gas and where distillate fuel oil is the back-up fuel. Distillates may contain water, dirt and often trace metals such as sodium, vanadium and lead which can cause severe damages to the gas turbines. Sodium being very often introduced through contamination with seawater during the fuel storage and delivery chain to the plant, and in combination, or with air borne salt ingested by the combustion air. Excursions of sodium in treated crude or heavy fuel oil can occur during unnoticed malfunctions of the fuel treatment plant, when changing the heavy fuel provenience without centrifuge adjustment, or by inadequate fuel handling. For burning heavy fuel, treatment with oil-soluble magnesium fuel additive is state of the art to inhibit hot corrosion caused by vanadium. Air borne salts, sodium, potassium and lead contaminated distillates, gaseous fuels, washed and unwashed crude and residual oil can not be handled by simple magnesium based additives. The addition of elements like silicon and/or chromium is highly effective in reducing turbine blade hot corrosion and hot section fouling. This paper describes field experience with the use of chromium containing fuel additive to reduce high temperature corrosion of hot section parts, as well as the interaction of oil-soluble chromium and magnesium-chromium additives on material behaviour of blades and vanes, and their economical and environmental aspects.

Austenitic High-Performance Materials for Non-Rotating Components in Stationary Gas Turbines

1988 ◽  
Author(s):  
K. Drefahl ◽  
Franz Hofmann
Keyword(s):  
Thermal Stress ◽  
High Temperature ◽  
Gas Turbines ◽  
High Performance ◽  
High Temperature Corrosion ◽  
Machining Processes ◽  
Resistance To Oxidation ◽  
High Fatigue ◽  
Good Workability ◽  
Made In

Five essential requirements for gas turbine materials exposed to high temperatures are discussed: - High resistance to oxidation and high temperature corrosion - High creep strength especially under condition of thermal stress - High fatigue strength under conditions of vibrational and thermal stress - Good workability since complicated deformation and machining processes are often necessary - Good weldability It is not always possible to make all these requirements totally compatible. This is because certain requirements have to be emphasized for reasons of application. In most cases compromises will have to be made in regard to workability.

High-Temperature Corrosion in Gas Turbines and Steam Boilers by Fuel Impurities—Part V: Lead Containing Slags

1975 ◽  
Vol 97 (3) ◽  
pp. 441-447 ◽  
Author(s):  
M. J. Zetlmeisl ◽  
W. R. May ◽  
R. R. Annand
Keyword(s):  
High Temperature ◽  
Linear Polarization ◽  
Gas Turbines ◽  
Sodium Level ◽  
High Temperature Corrosion ◽  
Corrosion Rates ◽  
Polarization Technique ◽  
Steam Boilers

The effect of lead on the corrosivity and friability of slags containing various ratios of sodium, vanadium, magnesium, and silicon has been evaluated. The application of the linear polarization technique was demonstrated. Lead produces very corrosive melts and tenacious slags. Magnesium will inhibit corrosion to acceptable levels and produce friable slags at 800 °C with a 4 to 1 ratio of additive to vanadium plus lead and a sodium to vanadium plus lead ratio no greater than 0.1. To produce friable slags at 900°, sodium must first be reduced to a sodium to vanadium plus lead ratio of 0.01. Second, a magnesium-silicon additive must be used at a 6 to 1 ratio of additive to vanadium plus lead. The corrosion rates of lead containing melts increases rapidly with sodium level.

Environmental Effects on the High-Temperature Corrosion of Superalloys in Present and Future Gas Turbines

1972 ◽  
Vol 94 (2) ◽  
pp. 149-153 ◽  
Author(s):  
S. Y. Lee ◽  
W. E. Young ◽  
C. E. Hussey
Keyword(s):  
High Temperature ◽  
Corrosion Rate ◽  
Surface Temperature ◽  
Gas Turbines ◽  
Critical Factor ◽  
High Temperature Corrosion ◽  
Operating Conditions ◽  
Dynamic Type ◽  
Type Test ◽  
Effects Of Temperature

Effects of temperature and contaminant levels on the high-temperature corrosion of superalloys used in gas turbines were investigated using pressurized passages which simulate the operating conditions of present-day gas turbines. The alloys were tested in a cooled configuration realistically simulating the air-cooled vanes and blades of a gas turbine. Conclusions are drawn as to the permissible level of contaminants and the effect of metal cooling on high-temperature corrosion. It is shown that the surface temperature of a blade or vane rather than the gas-stream temperature is the critical factor in determining the amount of attack to be expected at a given contaminant level and the amount of attack is an exponential function of this temperature. Furthermore, in a dynamic-type test no decrease in corrosion rate is noted at higher temperatures. It was concluded that the use of a 5 ppm Na/2 ppm V fuel would result in an excessive amount of attack with a metal surface temperature of 1500 deg F.

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