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Title: High-temperature interactions of alkali vapors with solids during coal combustion and gasification

Abstract

A temperature and concentration programmed reaction method is used to investigate the mechanism by which organically bound alkali is released from carbonaceous substrates. Vaporization of the alkali is preceded by reduction of oxygen-bearing groups during which CO is generated. A residual amount of alkali remains after complete reduction. This residual level is greater for potassium, indicating that potassium has stronger interactions with graphitic substrates that sodium. Other mineral substrates were exposed to high temperature alkali chloride vapors under both nitrogen and simulated flue gas atmospheres to investigate their potential application as sorbents for the removal of alkali from coal conversion flue gases. The compounds containing alumina and silica are found to readily adsorb alkali vapors and the minerals kaolinite, bauxite and emathlite are identified as promising alkali sorbents. The fundamentals of alkali adsorption on kaolinite, bauxite and emathlite are compared and analyzed both experimentally and through theoretical modeling. The experiments were performed in a microgravimetric reactor system; the sorbents were characterized before and after alkali adsorption using scanning Auger microscopy, X-ray diffraction analysis, mercury porosimetry and atomic emission spectrophotometry. The results show that the process is not a simple physical condensation, but a complex combination of several diffusion steps andmore » reactions.« less

Authors:
Publication Date:
Research Org.:
Arizona Univ., Tucson, AZ (USA)
OSTI Identifier:
6962817
Resource Type:
Miscellaneous
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; ADSORBENTS; PERFORMANCE TESTING; ALKALI METALS; ADSORPTION; BAUXITE; SORPTIVE PROPERTIES; KAOLINITE; AUGER ELECTRON SPECTROSCOPY; BENCH-SCALE EXPERIMENTS; CARBON MONOXIDE; CHEMICAL REACTIONS; CLEANING; COAL; COAL GASIFICATION; COMBUSTION; DIFFUSION; EMISSION SPECTROSCOPY; EVAPORATION; FLUE GAS; MATHEMATICAL MODELS; PHOTOMETRY; POROSIMETERS; POTASSIUM; REMOVAL; SODIUM; X-RAY DIFFRACTION; ALUMINIUM COMPOUNDS; ALUMINIUM ORES; ALUMINIUM SILICATES; CARBON COMPOUNDS; CARBON OXIDES; CARBONACEOUS MATERIALS; CHALCOGENIDES; COHERENT SCATTERING; DIFFRACTION; ELECTRON SPECTROSCOPY; ELEMENTS; ENERGY SOURCES; FOSSIL FUELS; FUELS; GASEOUS WASTES; GASIFICATION; MATERIALS; MEASURING INSTRUMENTS; METALS; MINERALS; ORES; OXIDATION; OXIDES; OXYGEN COMPOUNDS; PHASE TRANSFORMATIONS; SCATTERING; SILICATE MINERALS; SILICATES; SILICON COMPOUNDS; SORPTION; SPECTROSCOPY; SURFACE PROPERTIES; TESTING; THERMOCHEMICAL PROCESSES; WASTES; 014000* - Coal, Lignite, & Peat- Combustion; 010404 - Coal, Lignite, & Peat- Gasification; 010800 - Coal, Lignite, & Peat- Waste Management

Citation Formats

Punjak, W A. High-temperature interactions of alkali vapors with solids during coal combustion and gasification. United States: N. p., 1988. Web.
Punjak, W A. High-temperature interactions of alkali vapors with solids during coal combustion and gasification. United States.
Punjak, W A. 1988. "High-temperature interactions of alkali vapors with solids during coal combustion and gasification". United States.
@article{osti_6962817,
title = {High-temperature interactions of alkali vapors with solids during coal combustion and gasification},
author = {Punjak, W A},
abstractNote = {A temperature and concentration programmed reaction method is used to investigate the mechanism by which organically bound alkali is released from carbonaceous substrates. Vaporization of the alkali is preceded by reduction of oxygen-bearing groups during which CO is generated. A residual amount of alkali remains after complete reduction. This residual level is greater for potassium, indicating that potassium has stronger interactions with graphitic substrates that sodium. Other mineral substrates were exposed to high temperature alkali chloride vapors under both nitrogen and simulated flue gas atmospheres to investigate their potential application as sorbents for the removal of alkali from coal conversion flue gases. The compounds containing alumina and silica are found to readily adsorb alkali vapors and the minerals kaolinite, bauxite and emathlite are identified as promising alkali sorbents. The fundamentals of alkali adsorption on kaolinite, bauxite and emathlite are compared and analyzed both experimentally and through theoretical modeling. The experiments were performed in a microgravimetric reactor system; the sorbents were characterized before and after alkali adsorption using scanning Auger microscopy, X-ray diffraction analysis, mercury porosimetry and atomic emission spectrophotometry. The results show that the process is not a simple physical condensation, but a complex combination of several diffusion steps and reactions.},
doi = {},
url = {https://www.osti.gov/biblio/6962817}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Jan 01 00:00:00 EST 1988},
month = {Fri Jan 01 00:00:00 EST 1988}
}

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