Influence of particle structure changes on the rate of coal char reaction with CO/sub 2/
A common feature of gas-solid reactions is that the overall process involves several steps: (1) mass transfer of reactants and products from bulk gas phase to the internal surface of the reacting solid particle; (2) diffusion of gaseous reactants or products through the pores of a solid reactant; (3) adsorption of gaseous reactants on solid reactant sites and desorption of reaction products from solid surfaces; (4) the actual chemical reaction between the adsorbed gas and solid. In studying gas-solid reactants, we are concerned with these four phenomena and other phenomena which affect the overall rate of reaction and performance of industrial equipment in which these gas-solid reactions are carried out. These other phenomena include: heat transfer, flow of gases and solids through reactors, and changes in the solid structure, all of which affect the rate of diffusion and surface area available for reaction. Devolatilization causes structural changes reflected in an average weight loss of 41%, a decrease in the diffusion coefficient, and an increase in total surface area. The increase in surface area represents the opening of pores not accessible before devolatilization. This new pore structure has a greater resistance to diffusion. The small pores and enlarged pore form a more complex network of voids within the particles. The devolatilization causes an increase in total available surface area and a decrease in the diffusion coefficient. The heterogeneous chemical reaction causes continuous changes in the pore structure due to the consumption of carbon.
- Research Organization:
- Vanderbilt Univ., Nashville, TN
- OSTI ID:
- 7055647
- Report Number(s):
- CONF-820304-Vol.2
- Journal Information:
- Prepr. Pap. - Am. Chem. Soc., Div. Fuel Chem.; (United States), Vol. 27:1; Conference: 183. American Chemical Society annual meeting, Las Vegas, NV, USA, 27 Mar 1982
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON DIOXIDE
CHEMICAL REACTION KINETICS
CHARS
COAL
DEVOLATILIZATION
ACTIVATION ENERGY
CHEMICAL REACTIONS
COAL GASIFICATION
POROSITY
CARBON COMPOUNDS
CARBON OXIDES
CARBONACEOUS MATERIALS
CHALCOGENIDES
ENERGY
ENERGY SOURCES
FOSSIL FUELS
FUELS
GASIFICATION
KINETICS
MATERIALS
OXIDES
OXYGEN COMPOUNDS
PYROLYSIS PRODUCTS
REACTION KINETICS
THERMOCHEMICAL PROCESSES
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