Effect of mineral species on oil shale char combustion and steam gasification
Six oil shale samples with different mineral compositions were retorted identically and the resulting char was subjected to combustion kinetic studies using TGA techniques to determine what effect the various minerals which are present in the shale might have on the reaction rate. Three of the shales were also subjected to a steam gasification kinetic study and one shale ash was used to evaluate the water-gas shift reaction. The effects of mineral species on both char combustion and steam gasification rates were evaluated by selectively altering the mineral content. Combustion was bound to be first order with respect to both oxygen partial pressure and char remaining. A dynamic simulation of a TGA was developed to aid in extracting intrinsic chemical reaction rate data when gas-solid mass transfer was non-negligible. On the one Devonian shale, Michigan Antrim, the char combustion rate was successfully separated from the pyrite oxidation rate. Intrinsic combustion rate constants were found to vary from one shale to another by a factor of eight. Catalytic activity was attributed to alkali and alkaline earth oxides formed by mineral carbonate decomposition of nahcolite and calcite which resulted in an order of magnitude increase in the combustion rates. The steam gasification rates varied by a factor of five and followed the same Langmuir-Hinshelwood model typically used in the coal gasification literature. Product gases from steam gasification were analyzed and gave evidence of a rapid water-gas shift reaction which resulted in a hydrogen-rich mixture. Evidence of catalytic activity by calcium, potassium, magnesium and iron oxides was also found. The water-gas shift reaction over oil shale ash was found to follow Langmuir-Hinshelwood kinetics and was catalyzed by iron oxides.
- Research Organization:
- Washington State Univ., Pullman (USA)
- OSTI ID:
- 6913142
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
040402* -- Oil Shales & Tar Sands-- Surface Methods
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ASHES
BITUMINOUS MATERIALS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CARBONACEOUS MATERIALS
CATALYTIC EFFECTS
CHALCOGENIDES
CHARS
CHEMICAL ANALYSIS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMBUSTION
COMBUSTION KINETICS
DECOMPOSITION
ENERGY SOURCES
FOSSIL FUELS
FUELS
GASIFICATION
GRAVIMETRIC ANALYSIS
INDUSTRIAL PLANTS
IRON COMPOUNDS
IRON OXIDES
IRON SULFIDES
KINETICS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MASS TRANSFER
MATERIALS
MINERALS
OIL SHALE PROCESSING PLANTS
OIL SHALES
OXIDATION
OXIDES
OXYGEN COMPOUNDS
POTASSIUM COMPOUNDS
POTASSIUM OXIDES
PYRITE
PYROLYSIS PRODUCTS
QUANTITATIVE CHEMICAL ANALYSIS
REACTION KINETICS
RESIDUES
RETORTING
SHIFT PROCESSES
STEAM
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
WATER GAS PROCESSES