Flame Imprinted Characteristics of Ash Relevant to Boiler Slagging, Corrosion, and Erosion

1982 ◽  
Vol 104 (4) ◽  
pp. 858-866 ◽  
Author(s):  
E. Raask
Keyword(s):  
High Temperature ◽  
Surface Properties ◽  
Coal Ash ◽  
Interface Behavior ◽  
Boiler Plant ◽  
Temperature Changes ◽  
Brief Assessment ◽  
Coal Particles ◽  
Pulverized Fuel ◽  
Subsequent Behavior

Pulverized fuel flames imprint marked characteristics on different particulate species which influence their subsequent behavior in boiler plant. The paper discusses some of the high temperature changes, namely, the transformation of irregularly shaped mineral granulates to spherical shapes found in ash, coal/ash interface behavior and the surface properties of semi-molten ash particles, combustion of the ash-rich coal particles, and the release of potassium from aluminosilicates. This is followed by a brief assessment of relevance of the findings to boiler slagging, corrosion and erosion.

POTOMAC

Alloy Digest ◽  
1975 ◽  
Vol 24 (8) ◽  
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Heat Treating ◽  
General Purpose ◽  
Low Carbon ◽  
Repeated Heating ◽  
Temperature Changes ◽  
Heating And Cooling ◽  
Temperature Performance ◽  
Heat Checking

Abstract POTOMAC is a general-purpose, low-carbon, chromium-molybdenum-tungsten hot-work steel. It has excellent resistance to shock and heat checking after repeated heating and cooling. Potomac is suitable for hot-work applications involving severe conditions of shock and sudden temperature changes. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fracture toughness. It also includes information on high temperature performance as well as forming, heat treating, and machining. Filing Code: TS-290. Producer or source: Allegheny Ludlum Corporation.

Research on Temperature Changes and Microstructure Evolution of Steel Target after the Penetration by Copper Jet

2011 ◽  
Vol 311-313 ◽  
pp. 953-956
Author(s):  
Hao Chen ◽  
Gang Tao
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Temperature Distribution ◽  
Microstructure Evolution ◽  
Deformation Zone ◽  
Superplastic Deformation ◽  
Theoretical Formula ◽  
Temperature Changes ◽  
Normal Deformation ◽  
Steel Target

In order to study dynamic response of metal, this paper makes use of theoretical formula to investigate changes of temperature and grain size on steel target after the penetration of copper jet based on data gathered from the experiments. Deformed target penetrated by copper jet could be divided into superplastic deformation zone and normal deformation zone according to the different microstructure. Temperature distribution of each deformation zones is in turn calculated by two constitutive equations. The results indicate that areas with high temperature concentrate on the narrow zone near the penetrated channel. Then, the calculation of grain size conforms to the observation. It is obviously proven that the method used in this paper is trustworthy for calculating the changes of temperature and grain size of target caused by penetration.

High-Temperature Erosion Resistance of Coatings for Gas Turbine

1992 ◽  
Vol 114 (2) ◽  
pp. 242-249 ◽  
Author(s):  
W. Tabakoff ◽  
A. Hamed ◽  
M. Metwally ◽  
M. Pasin
Keyword(s):  
High Temperature ◽  
Protective Coatings ◽  
Coal Ash ◽  
Mass Effect ◽  
Impact Angle ◽  
Unit Weight ◽  
Weight Losses ◽  
Aluminide Coatings ◽  
Particle Flows ◽  
The Impact

An experimental investigation was conducted to study the ash particle rebound characteristics and the associated erosion behavior of superalloys and aluminide coatings subjected to gas-particle flows at elevated temperature. A three-component LDV system was used to measure the restitution parameters of 15 micron mean diameter coal-ash particles impacting some widely used superalloys and coatings at different angles. The presented results show the variation of the particle restitution ratios with the impingement angle for the coated and uncoated superalloys. The erosion behaviors of INCO-738, MAR 246 and X40 superalloys and protective coatings C, N, RT22 and RT22B also have been investigated experimentally at high temperature using a specially designed erosion tunnel. The erosion results show the effect of velocity, temperature and the impact angle on the erosion rate (weight loss per unit weight of particles). Based on the experimental results of the particle mass effect on both weight losses and erosion rates, the coating lives have been estimated for different particle concentrations.

346. Measurements of the rate of change of temperature in high temperature-short time pasteurization plant

1947 ◽  
Vol 15 (1-2) ◽  
pp. 18-23
Author(s):  
F. Steghart
Keyword(s):  
High Temperature ◽  
Time Constant ◽  
Rate Of Change ◽  
Hot Water ◽  
Water Pipe ◽  
Temperature Changes ◽  
Rates Of Change ◽  
High Temperature Short Time ◽  
Short Time

It has recently been claimed that in modern high temperature-short time pasteurization plant fluctuations in temperature of the order of 1° F./sec. are unusual and probably artefacts, and that an instantaneous drop is certainly fictitious.It has, nevertheless, been shown that such rapid drops in temperature do in fact occur frequently in high temperature-short time plants of the type investigated. The plant investigated was not of the latest design incorporating devices for speeding up the control by injecting steam directly into the hot-water pipe.Temperature changes of the order of those in question were first observed by Mattick & Hiscox(1) of the National Institute for Research in Dairying, who carried out tests on pasteurization plant using a small mirror galvanometer with a very short time constant. The maximum rates of change were, however, not observed.

Fracture Mechanics of Y2O3 Ceramics at High Temperatures

2014 ◽  
Vol 89 ◽  
pp. 88-93
Author(s):  
Marek Boniecki ◽  
Zdzislaw Librant ◽  
Władysław Wesołowski ◽  
Magdalena Gizowska ◽  
Marcin Osuchowski ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
High Temperature ◽  
Fracture Mechanics ◽  
High Purity ◽  
Room Temperature ◽  
Bending Strength ◽  
Hot Isostatic Pressing ◽  
Temperature Changes ◽  
Four Point Bending

Fracture toughness KIc and four-point bending strength σc at high temperature (up to 1500 °C) of Y2O3 ceramics of various grain size were measured. The ceramics were prepared by pressureless air sintering and next hot isostatic pressing of high purity (99.99%) Y2O3 powder. Relative density of about 99 % was achieved. Photos of microstructures revealed small pores distributed mainly inside grains. For smallest grain size (2 - 9 μm) ceramics KIc and σc are almost constant from 20 ° to 1200 °C and next they decrease. For biggest grain size (about 44 μm) they increase up to 800 °C and next they keep constant up to 1200 °C. The micrographs analyses of fracture surfaces indicated that transgranular mode of fracture at room temperature changes to almost intergranular at higher temperatures.

Effects of High Temperature on Survival of the Giant Scallop

1958 ◽  
Vol 15 (6) ◽  
pp. 1189-1211 ◽  
Author(s):  
L. M. Dickie
Keyword(s):  
High Temperature ◽  
Temperature Acclimation ◽  
Direct Result ◽  
Acclimation Temperature ◽  
Lethal Temperature ◽  
Temperature Changes ◽  
Naturally Occurring ◽  
Special Circumstances ◽  
Summer Decline ◽  
Sudden Temperature Change

Upper lethal temperatures of scallops are raised 1 °C. by each increase of 5 °C. in acclimation temperature. Acclimation upwards is fairly rapid (average 1.7 °C. per day over part of the range). Loss of acclimation to high temperature is slow, and appears to take as long as 3 months. There is a winter-to-summer decline in lethal temperature. It appears that naturally occurring water temperatures over 23.5 °C. will be lethal to scallops and directly responsible for mortalities. Temperatures over 21 °C. may also be a direct cause of mortalities but only in special circumstances could mortalities occur as a direct result of temperatures below this. In the "sub-lethal" temperature range, sudden temperature changes upward or downward may so reduce scallop mobility as to make them easier prey to enemies. In this way sudden temperature change could be an indirect cause of increased mortality.

Surface properties of coal particles in aqueous media II. Adhesion of coal particles to polymeric substrates

1986 ◽  
Vol 17 (2) ◽  
pp. 143-157 ◽  
Author(s):  
D.R. Absolom ◽  
K. Eom ◽  
E.I. Vargha-Butler ◽  
H.A. Hamza ◽  
A.W. Neumann
Keyword(s):  
Surface Properties ◽  
Aqueous Media ◽  
Coal Particles ◽  
Polymeric Substrates
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