Viscosity and Phase Transformation in Coal Ash Slags near and below the Temperature of Critical Viscosity

1994 ◽  
Vol 8 (6) ◽  
pp. 1324-1336 ◽  
Author(s):  
Jan W. Nowok
AIChE Journal ◽  
2011 ◽  
Vol 57 (10) ◽  
pp. 2921-2925 ◽  
Author(s):  
Wenjia Song ◽  
Yanhe Dong ◽  
Yongqiang Wu ◽  
Zibin Zhu
Keyword(s):  
Coal Ash ◽  

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
B. Barker ◽  
B. Casaday ◽  
P. Shankara ◽  
A. Ameri ◽  
J. P. Bons

Coal ash deposition was numerically modeled on a GE-E3 high pressure turbine vane passage. A model was developed, in conjunction with FLUENT™ software, to track individual particles through the turbine passage. Two sticking models were used to predict the rates of deposition which were subsequently compared to experimental trends. The strengths and limitations of the two sticking models, the critical viscosity model and the critical velocity model, are discussed. The former model ties deposition exclusively to particle temperature while the latter considers both the particle temperature and velocity. Both incorporate some level of empiricism, though the critical viscosity model has the potential to be more readily adaptable to different ash compositions. Experimental results show that both numerical models are reasonably accurate in predicting the initial stages of deposition. Beyond the initial stage of deposition, for which transient effects must be accounted.


Author(s):  
B. Barker ◽  
B. Casaday ◽  
P. Shankara ◽  
A. Ameri ◽  
J. P. Bons

Coal ash deposition was numerically modeled on a GE-E3 high pressure turbine vane passage. A model was developed, in conjunction with Fluent™ software, to track individual particles through the turbine passage. Two sticking models were used to predict the rates of deposition which were subsequently compared to experimental trends. The strengths and limitations of the two sticking models, the critical viscosity model and the critical velocity model, are discussed. The former model ties deposition exclusively to particle temperature while the latter considers both the particle temperature and velocity. Both incorporate some level of empiricism, though the critical viscosity model has the potential to be more readily adaptable to different ash compositions. Experimental results show that both numerical models are reasonably accurate in predicting the initial stages of deposition. Beyond the initial stage of deposition, transient effects must be accounted for.


Fuel ◽  
2019 ◽  
Vol 253 ◽  
pp. 1521-1530 ◽  
Author(s):  
Tinggui Yan ◽  
Jin Bai ◽  
Lingxue Kong ◽  
Huaizhu Li ◽  
Zhigang Wang ◽  
...  
Keyword(s):  
Coal Ash ◽  

Author(s):  
Shiro Fujishiro

The Ti-6 wt.% Al-4 wt.% V commercial alloys have exhibited an improved formability at cryogenic temperature when the alloys were heat-treated prior to the tests. The author was interested in further investigating this unusual ductile behavior which may be associated with the strain-induced transformation or twinning of the a phase, enhanced at lower temperatures. The starting materials, supplied by RMI Co., Niles, Ohio were rolled mill products in the form of 40 mil sheets. The microstructure of the as-received materials contained mainly ellipsoidal α grains measuring between 1 and 5μ. The β phase formed an undefined grain boundary around the a grains. The specimens were homogenized at 1050°C for one hour, followed by aging at 500°C for two hours, and then quenched in water to produce the α/β mixed microstructure.


Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.


Author(s):  
K Das Chowdhury ◽  
R. W. Carpenter ◽  
W. Braue

Research on reaction-bonded SiC (RBSiC) is aimed at developing a reliable structural ceramic with improved mechanical properties. The starting materials for RBSiC were Si,C and α-SiC powder. The formation of the complex microstructure of RBSiC involves (i) solution of carbon in liquid silicon, (ii) nucleation and epitaxial growth of secondary β-SiC on the original α-SiC grains followed by (iii) β>α-SiC phase transformation of newly formed SiC. Due to their coherent nature, epitaxial SiC/SiC interfaces are considered to be segregation-free and “strong” with respect to their effect on the mechanical properties of RBSiC. But the “weak” Si/SiC interface limits its use in high temperature situations. However, few data exist on the structure and chemistry of these interfaces. Microanalytical results obtained by parallel EELS and HREM imaging are reported here.


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