Performance and modeling of fluidized-bed coal gasifiers
This work explores the constraints of pressurized fluidized-bed coal reactors and their commercial potential. A unique predictive kinetic model that accounts for coal/char oxidation and gasification, water-gas shift, heat losses, and recycle and purge streams was developed. The model predicts carbon conversion, reactor temperature, bed holdup, and 30 other state variables. Pilot-plant simulation indicates that they have been operated in the wrong regime for commercial scale up. The inability to operate in a commercially attractive regime can be attributed to excessive fines recycle and the complex ash-separation bottom zone which requires large amounts of excess gas to operate. Commercially-sized reactor simulation indicates that both of the currently developed designs are of no commercial value for fuel gas generation from high-grade bituminous coal. Simulation with Western coal indicates that fluidized-bed gasifiers are suitable for partly dried Western coals and lignites. This advantage is due to faster reaction rates and a more favorable stoichiometry. Under common gasification conditions with Eastern coal the operable range was determined to be kinetically constrained and far from thermodynamic equilibrium. A unique stoichiometric invariance technique has been developed for coal gasification. The relation permits the calculation of steam-free mass balances; provides a data consistency cross-check; substitutes for invalid measurements; and enables on-line metering of critical process parameters such as carbon conversion and cold-gas efficiency.
- Research Organization:
- City Univ. of New York, NY (USA)
- OSTI ID:
- 6636639
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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