A Laboratory Study of High-Temperature Corrosion on Fireside Surfaces of Coal-Fired Steam Generators

1968 ◽  
Vol 90 (2) ◽  
pp. 193-198 ◽  
Author(s):  
S. A. Goldberg ◽  
J. J. Gallagher ◽  
A. A. Orning
Keyword(s):  
High Temperature ◽  
Steam Generators ◽  
Fireside Corrosion ◽  
Significant Information ◽  
Metal Chlorides ◽  
Mixed Alkali ◽  
Electrolytic Corrosion ◽  
Gas Atmosphere ◽  
Experimental Approaches ◽  
Gas Flame

Three experimental approaches gave significant information on high-temperature fireside corrosion: 1 Sodium and potassium chlorides, injected through a gas flame, were deposited as such and then converted to sulfates on an iron surface. 2 Samples of mixed alkali and iron sulfates first showed decomposition and then formed melts at temperatures as low as 1070 deg F. This temperature is within the range that might be expected for fireside surface temperatures on superheater and reheater tubes of large steam generators. 3 Alkali metal chlorides and sulfates, in partial coverage of metal disks and in a flue gas atmosphere, formed fused deposits at temperatures as low as 900 deg F. Complex alkali iron sulfates may cause corrosion either by direct electrolytic corrosion or by altering the normally protective iron oxide scale so that the metal is exposed to direct oxidative corrosion.

Zaczyny cementowe z dodatkiem nanorurek węglowych do uszczelniania otworów wiertniczych o wysokiej temperaturze i ciśnieniu złożowym (150°C, 90 MPa)

Nafta-Gaz ◽  
2021 ◽  
Vol 77 (5) ◽  
pp. 323-331
Author(s):  
Miłosz Kędzierski ◽  
◽  
Marcin Rzepka ◽  
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strength ◽  
High Temperature ◽  
Rheological Parameters ◽  
External Diameter ◽  
Mechanical Parameters ◽  
Cement Slurry ◽  
Significant Information ◽  
High Temperature And Pressure ◽  
Temperature And Pressure

The article presents the results of the influence of carbon nanotubes on the mechanical parameters of cement stones under high temperature and pressure conditions (150°C, 90 MPa). The tests used multi-walled carbon nanotubes (MWCNTs) with an external diameter of 10–20 nm and a length of 10–30 μm. Cement slurries contained 0.1% of CNTs bwoc (by the weight of cement). Laboratory tests of cement slurries were carried out at the Oil and Gas Institute – National Research Institute. The tests were carried out under conditions of increased pressure and temperature at 150°C, 90 MPa. Cement slurries were prepared on the basis of class G drilling cement. Developing recipes were guided by the requirements to be met by cement slurry for the cementing of casing in the conditions of high temperature and reservoir pressures. The densities of tested slurries ranged from 1900 kg/m3 to 2250 kg/m3 (slurries with the addition of hematite). The cement slurries were tested for density, fluidity, rheological parameters, filtration and thickening time. Compressive strength tests and measuring adhesion were carried out after 2, 7, 14 and 28 days. Cement slurry recipes with very good technological parameters were developed and after curing (after 28 days of hydration) had very high values of compressive strength, reaching up to 45 MPa. Cements were characterized by high values of adhesion to pipes reaching up 7 MPa after 28 days. The research showed significant information about possible applications of carbon nanotubes to modify the cement slurry under conditions of high temperature and pressure. The conducted tests confirmed that the addition of even small amounts of CNTs improves the mechanical parameters of the cement stone compared to the base sample without such addition, and also reduces the thickening time of cement slurries and reduces filtration. It is investigated that CNTs addition increases the viscosity and yield point of cement slurry. As a result, slurries with the addition of MWCNTs will more effectively displace the mud from the borehole and significantly affect the quality of cementation.

scholarly journals Features of thermodynamic and thermal processes in hydrogen combustion units and systems on their basis

2021 ◽  
Vol 2039 (1) ◽  
pp. 012032
Author(s):  
A I Schastlivtsev ◽  
V I Borzenko
Keyword(s):  
High Temperature ◽  
Combustion Products ◽  
Hydrogen Combustion ◽  
Thermal Processes ◽  
Steam Generators ◽  
Temperature Combustion ◽  
Main Components ◽  
High Temperature Combustion

Abstract The main types and designs of hydrogen combustion units (HCU), including hydrogen-oxygen steam generators, superheaters and air heaters of various power levels, are considered. The main problems arising in the development, creation and testing of such installations are determined, including the problems of cooling the most heat-stressed units, mixing of the main components of the fuel and oxidizer, mixing of high-temperature combustion products and ballasting components, problems associated with the completeness of hydrogen combustion and ensuring safety during operation.

scholarly journals High Temperature Texture Goniometer for in Situ Measurements of Transformation Textures

1998 ◽  
Vol 30 (3-4) ◽  
pp. 125-132
Author(s):  
G. Brückner ◽  
F. R. Reher ◽  
G. Gottstein
Keyword(s):  
High Temperature ◽  
Texture Evolution ◽  
Sample Surface ◽  
Texture Measurement ◽  
X Ray ◽  
Reducing Gas ◽  
Gas Atmosphere ◽  
Computer Controlled

A high temperature stage was designed for mounting onto a computer controlled four circle X-ray texture goniometer. This technique allowed to conduct in situ texture measurement, i.e. the determination of the texture evolution during rather than subsequent to annealing. The device was employed for temperatures up to 1000°C.The furnace consisted of a resistance wire of Pt30Rh, which was isolated against the specimen with Al2O3 glue. The furnace with the specimen was covered by a hemispherical KaptonTM foil. Inside the hemisphere a reducing gas atmosphere was used to avoid oxidation of the sample surface.

Updated Case Study of Fireside Corrosion Management in an RDF Fired Energy-From-Waste Boiler

2010 ◽  
Author(s):  
Stephen Vrchota ◽  
Tim Peterson
Keyword(s):  
High Temperature ◽  
Material Selection ◽  
Cost Effective ◽  
Fireside Corrosion ◽  
Alloy 625 ◽  
Water Wall ◽  
Refuse Derived Fuel ◽  
Corrosion Resistant Alloy ◽  
Energy From Waste

Fireside corrosion management in energy-from-waste (EfW) boilers is the leading cost of boiler maintenance. The combustion of refuse-derived fuel (RDF) processed from municipal solid waste in a boiler for power generation produces a very corrosive environment for boiler tube materials. Water wall corrosion has been greatly reduced by the use of Alloy 625 overlay in the highest corrosion areas. This paper will describe the progression of water wall corrosion up the boiler walls and novel attempts to reduce this problem. This paper presents an updated case study conducted at the Great River Energy plant in Elk River, MN from 2003–2009 on corrosion management. Areas to be addressed are protection of exposed carbon steel water wall tubes, management of Alloy 625 weld overlay on the water walls and corrosion in the high temperature superheat sections. Methods for testing and maintaining the corrosion resistant Alloy 625 cladding are reviewed. High temperature superheat material selection and shielding are reviewed with information leading to a cost effective solution that requires superheat replacement every three years with very few tube failures between replacements.

Lateral grain growth in poly-Si films by gas flame high temperature annealing

1996 ◽  
Vol 441 ◽  
Author(s):  
W. F. Qu ◽  
A. Kitagawa ◽  
Y. Masaki ◽  
M. Suzuki
Keyword(s):  
High Temperature ◽  
Tensile Stress ◽  
Compressive Stress ◽  
Grain Growth ◽  
Strain Energy ◽  
Driving Forces ◽  
Stress Distributions ◽  
High Temperature Annealing ◽  
Gas Flame ◽  
Si Films

AbstractPoly-Si films with the preferential orientation to a random, a (100) and a (110) texture were annealed using a flat gas flame. Remarkable lateral grain growth of (111) grains was observed for poly-Si films with a random and a (110) texture, while in (100) texture films the growth of (100) grains predominated over other grains. There existed tensile stress in as-prepared films. Grains with different orientation were under a different tensile stresses, and such stress distributions on the orientation of grains were different for different textures. The tensile stress was found to become larger in grown grains after high temperature annealing, while the stress on shrunken grains decreased or turned to compressive stress after annealing. These results indicate that strain energy stored in grains is one of the important driving forces in secondary grain growth.

Positive Effect of Hydrogen Treatment in Titanium Ti-6Al-4V Alloy

2011 ◽  
Vol 183 ◽  
pp. 179-184 ◽  
Author(s):  
Maria Sozańska
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Titanium Hydride ◽  
High Stress ◽  
Absorption Capacity ◽  
Hydrogen Gas ◽  
Hydrogen Treatment ◽  
Two Phase ◽  
Deformation Phase ◽  
Gas Atmosphere

Positive nature of the effects of hydrogen on the properties of titanium alloys is manifested in the high temperature hydrogen treatment (HTM - Hydrogen Treatment of Materials), where hydrogen is temporary alloying component. This is possible because of the high values ​​of diffusion coefficients can be easily introduced into the titanium and it just as easily removed. Titanium and its alloys exhibit a high affinity for hydrogen absorption capacity, about 60% at. hydrogen at 600 °C. The hydrogen in titanium alloy is present in the form – an interstitial solution or titanium hydride. Since the specific volume of titanium hydride is about 13 ÷ 17% higher compared to α phase, it is high stress in the crystal lattice of this phase leads to local plastic deformation and large deformation phase. The paper presents the results of the possibilities of hydrogen using as a temporary alloying element in Ti-6Al-4V alloy. Treatment of hydrogen alloy consisted of three stages: hydrogenation in hydrogen gas atmosphere at 650 °C, a cyclic hydrogen-treatment (3 cycles 650 °C or 950 °C to 250 °C) and a dehydrogenation in vacuum (550 °C). It was shown that hydrogen affects appreciably changes the microstructure of surface layer of the tested titanium alloy. The aim of this study is thus to determine the effect of hydrogen on the two-phase microstructure, hardness, and corrosion resistance of the titanium alloy Ti-6Al-4V due to high-temperature hydrogen treatment.

Corrosion of Superheaters and Reheaters of Pulverized-Coal-Fired Boilers, II

1961 ◽  
Vol 83 (4) ◽  
pp. 468-474 ◽  
Author(s):  
Carl Cain ◽  
Wharton Nelson
Keyword(s):  
High Temperature ◽  
Liquid Phase ◽  
Gas Phase ◽  
Coal Ash ◽  
Pulverized Coal ◽  
Corrosion Mechanism ◽  
Fireside Corrosion ◽  
Factors Affecting ◽  
Ferritic Alloys ◽  
Tube Metal

This paper deals with studies of high-temperature fireside corrosion of reheater and superheater tubes in pulverized-coal-fired boilers. Factors affecting the temperature range and rate of corrosion by molten complex alkali sulfates are described. The influence of sulfides, produced by reaction of complex sulfates with tube metal, on corrosion rate is discussed. The similarity of coal-ash to oil-ash corrosion mechanism is brought out. Methods for distinguishing liquid phase from gas-phase corrosion on ferritic alloys are presented.

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