Char crystalline transformations during coal combustion and their implications for carbon burnout. Semiannual technical progress report, July 1, 1995--January 1, 1996
Recent work at Sandia National Laboratories, Imperial College, and the U.K. utility PowerGen, has identified an important mechanism believed to have a large influence on unburned carbon levels from pulverized coal fired boilers. That mechanism is char carbon crystalline rearrangements on subsecond times scales at temperatures of 1,800--2,500 K, which lead to char deactivation in the flame zones of furnaces. The so-called thermal annealing of carbons is a well known phenomenon, but its key role in carbon burnout has only recently been appreciated, and there is a lack of quantitative data in this time/temperature range. In addition, a new fundamental tool has recently become available to study crystalline transformations, namely high resolution transmission electron microscopy (HRTEM) fringe imaging, which provides a wealth of information on the nature and degree of crystallinity in carbon materials such as coal chars. Motivated by these new developments, this University Coal Research project has been initiated with the following three goals: to determine transient, high-temperature, thermal deactivation kinetics as a function of parent coal and temperature history; and to characterize the effect of this thermal treatment on carbon crystalline structure through high-resolution transmission electron microscopy and specialized, quantitative image analysis. Work is currently underway on the following three tasks: experimental technique development; thermal deactivation kinetics; and crystal structure characterization. This report discusses the development of the transient heat treatment apparatus, and new algorithms for HRTEM image analysis.
- Research Organization:
- Brown Univ., Providence, RI (United States). Div. of Engineering
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-95PC95205
- OSTI ID:
- 231415
- Report Number(s):
- DOE/PC/95205-1; ON: DE96009309; TRN: AHC29611%%61
- Resource Relation:
- Other Information: PBD: [1996]
- Country of Publication:
- United States
- Language:
- English
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Char Crystalline Transformations During Coal Combustion and Their Implication for Carbon Burnout
Char crystalline transformations during coal combustion and their implications for carbon burnout. Semiannual technical progress report, 1 January 1996--1 July 1996