Sodium Sulphate Induced Hot Corrosion of Pure Fe, Mn and Cr in Combustion Gas

1991 ◽  
Vol 20-28 ◽  
pp. 3413-3422
Keyword(s):  
Hot Corrosion ◽  
Sodium Sulphate ◽  
Combustion Gas

Unusual Application of Plasma Sprayed Coating for Boiler Tubes in Oil-Fired Boilers

1998 ◽  
Author(s):  
K. Tani ◽  
Y. Harada ◽  
Y. Kobayashi
Keyword(s):  
Heat Exchanger ◽  
Hot Corrosion ◽  
Heat Load ◽  
Chemical Cleaning ◽  
Boiler Water ◽  
Combustion Gas ◽  
Water Side ◽  
Boiler Tubes ◽  
Sprayed Coating ◽  
Plasma Sprayed

Abstract The unusual effects of plasma sprayed coating on the fire-side of evaporator tubes located in an oil-fired steam generating boiler are discussed. The main heat transfer surfaces are constructed by heat exchanger tubes, evaporator tubes and superheaters. Maintenance to prevent of the boiler failure or the preserve heat exchanger effectiveness is a very important factor in the operation of boiler facilities. In a boiler which employs heavy gravity oil as a fuel, plasma sprayed Ni-Cr alloy has often been applied to boiler tubes for the relief of hot corrosion by combustion gas. However, the circulation of boiler water causes an internal deposit to form on the inner wall of evaporator tubes. The internal deposit generates excess heat load against the tubes. As the overheating of the tubes often causes the evaporator tubes to fail, they are chemically cleaned periodically. In this paper, the influence of Ni-Cr plasma sprayed coating for the heat flux, which dominates the formation of the internal deposit, is investigated. Ni-Cr plasma sprayed coating is substitutionally hot corrosion resistant and is a composite coating into which the fuel ash containing a vanadium or sulfur compound are interstitially penetrated and solidified. It is derived that the existence of the coating on the fire-side of the evaporator tubes normalizes the heat load in their inner walls. Moreover, the suppression of internal deposit formation decreases the frequency of chemical cleaning for tubes. The dual effects of plasma sprayed coating for hot corrosion resistance in the fire side and the suppression of internal deposit on the water side of the tubes are reported.

scholarly journals Hot Corrosion Morphology of Ni-base Superalloy MM-247 Corroded in High Velocity Combustion Gas Stream

1989 ◽  
Vol 38 (4) ◽  
pp. 211-217
Author(s):  
Akira Ishida ◽  
Isao Tomizuka ◽  
Atsushi Takei ◽  
Michio Yamazaki
Keyword(s):  
High Velocity ◽  
Hot Corrosion ◽  
Corrosion Morphology ◽  
Combustion Gas ◽  
Base Superalloy

The mechanism of sodium sulphate-induced low temperature hot corrosion of pure iron

1990 ◽  
Vol 30 (4-5) ◽  
pp. 327-349 ◽  
Author(s):  
V. Buscaglia ◽  
P. Nanni ◽  
C. Bottino
Keyword(s):  
Low Temperature ◽  
Hot Corrosion ◽  
Pure Iron ◽  
Sodium Sulphate

The Increasing Complexity of Hot Corrosion

2017 ◽  
Author(s):  
David A. Shifler
Keyword(s):  
Sodium Sulfate ◽  
Hot Corrosion ◽  
Degradation Process ◽  
Potassium Salts ◽  
Protective Oxide ◽  
Sulfate Salt ◽  
Combustion Gas ◽  
Accelerated Degradation ◽  
Surrounding Environment ◽  
Air Intake

It has been conjectured that if sulfur in fuel is removed, engine materials will cease to experience attack from hot corrosion, since this sulfur has been viewed as the primary cause of hot corrosion and sulfidation. Historically, hot corrosion has been defined as an accelerated degradation process that generally involves deposition of corrosive species (e.g., sulfates) from the surrounding environment (e.g., combustion gas) onto the surface of hot components, resulting in destruction of the protective oxide scale. Most papers in the literature, since the 1970s, consider sodium sulfate salt as the single specie contributing to hot corrosion. Recent Navy standards for Navy F-76 and similar fuels have dropped the sulfur content down to 15 parts per million (ppm). Most observers believe that the removal of sulfur will end hot corrosion events in the Fleet. However, the deposit chemistry influencing hot corrosion is known to be much more complex consisting of multiple sulfates and silicates. Sulfur species may still enter the combustion chamber via ship's air intake, which may include seawater entrained in the air. In addition to sodium sulfate, seawater contains magnesium, calcium and potassium salts, and atmospheric contaminants that may contribute to hot corrosion. This paper will cover some of the revised understanding of hot corrosion and consider other possible contaminants that could further complicate a full understanding of hot corrosion.

scholarly journals Hot Corrosion Behavior of Nickel-base Cast Superalloys in Combustion Gas Stream

1986 ◽  
Vol 72 (9) ◽  
pp. 1391-1398
Author(s):  
Akira ISHIDA ◽  
Isao TOMIZUKA ◽  
Takashi KIMURA ◽  
Kazuyuki OGAWA ◽  
Michio YAMAZAKI
Keyword(s):  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Combustion Gas ◽  
Nickel Base

The Increasing Complexity of Hot Corrosion

2017 ◽  
Author(s):  
David A. Shifler
Keyword(s):  
Sodium Sulfate ◽  
Hot Corrosion ◽  
Degradation Process ◽  
Potassium Salts ◽  
Protective Oxide ◽  
Sulfate Salt ◽  
Combustion Gas ◽  
Accelerated Degradation ◽  
Surrounding Environment ◽  
Air Intake

It has been conjectured that if sulfur in fuel is removed, engine materials will cease to experience attack from hot corrosion, since this sulfur has been viewed as the primary cause of hot corrosion and sulfidation. Historically, hot corrosion has been defined as an accelerated degradation process that generally involves deposition of corrosive species (e.g., sulfates) from the surrounding environment (e.g., combustion gas) onto the surface of hot components, resulting in destruction of the protective oxide scale. Most papers in the literature, since the 1970s, consider sodium sulfate salt as the single specie contributing to hot corrosion. Recent Navy standards for Navy F-76 and similar fuels have dropped the sulfur content down to 15 parts per million (ppm). Most observers believe that the removal of sulfur will end hot corrosion events in the Fleet. However, the deposit chemistry influencing hot corrosion is known to be much more complex consisting of multiple sulfates and silicates. Sulfur species may still enter the combustion chamber via ship’s air intake, which may include seawater entrained in the air. In addition to sodium sulfate, seawater contains magnesium, calcium and potassium salts, and atmospheric contaminants that may contribute to hot corrosion. This paper will cover some of the revised understanding of hot corrosion and consider other possible contaminants that could further complicate a full understanding of hot corrosion.

Comparison of Sodium Sulphate Deposition Rate Models Based on Operational Factors Influencing Hot Corrosion Damage in Aero-Engines

2020 ◽  
Author(s):  
Evangelia Pontika ◽  
Panagiotis Laskaridis ◽  
Theoklis Nikolaidis ◽  
Max Koster
Keyword(s):  
Gas Turbine ◽  
Analysis Of Variance ◽  
Deposition Rate ◽  
Hot Corrosion ◽  
Molten Salts ◽  
Experimental Studies ◽  
Corrosion Damage ◽  
Sodium Sulphate ◽  
Operating Conditions ◽  
Aircraft Engines

Abstract Hot corrosion is defined as the accelerated oxidation/sulphidation in the presence of alkali metal molten salts. It is a form of chemical attack that causes good metal loss. Current lifing models in aircraft engines focus on creep, fatigue and oxidation while hot corrosion damage has been overlooked as being of secondary importance. However, the absence of hot corrosion lifing models for aircraft engines often leads to unexpected and unexplained hot corrosion findings by aircraft engine operators and Maintenance, Repair and Overhaul (MRO) providers during inspections. Although hot corrosion does not cause failure on its own, the interaction with other damage mechanisms can reduce component life significantly, consequently, there is a requirement for including hot corrosion in the damage prediction process of aircraft engines. In both theoretical and experimental studies in literature, deposition of molten salts is identified as one of the primary conditions for hot corrosion to occur and an increased amount of deposited liquid salts accelerates the attack. Currently, most hot corrosion studies are limited to experimental testing of superalloys which are pre-coated with a controlled layer of salts. Such experimental studies are disconnected from gas turbine operating conditions during service. The present paper analyses two deposition rate models applicable to gas turbine operating conditions using Design of Experiments. Design space exploration is presented by taking into account gas turbine operating parameters which vary during a flight as well as temperature ranges where hot corrosion can occur. Analysis of variance is presented for 6 input parameters using Box-Behnken 3-level factorial design. Results from the Analysis of Variance indicate that the deposition rate models are sensitive to pressure and salt concentration in the gas flow. Finally, the saturation point of sodium sulphate has been investigated within the operating range of gas turbine and it was found that it can vary significantly under different conditions.

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