Characterisation of solid fuels at pressurised fluidised bed gasification conditions
- Abo Akademi Univ. (Finland)
The gasification or co-gasification of solid fuels (coal, peat, wood) in air-blown fluidised bed gasifiers is receiving continued attention as an alternative to entrained flow gasifiers which in general are oxygen-blown. Fluidised bed gasification of wood and wood-waste at elevated pressures, and the so-called air-blown gasification cycle are examples of processes which are under development in Europe, based on complete or partial gasification of a solid fuel in a pressurised fluidised bed. At the same time, fuel characterisation data for the combination of temperature, pressure and fuel particle heating rate that is encountered in fluidised bed gasification are very scarce. Quantitative data on the characterisation of fuels for advanced combustion and gasification technologies based on fluidised beds are given, as a result from our participation to the JOULE 2 extension project on clean coal technology of the European Community. Eleven solid fuels, ranging from coal via peat to wood, have been studied under typical fluidised bed gasification conditions: 800-1000{degrees}C, 1-25 bar, fuel heating rate in the order of 100-1000{degrees}C/s. Carbon dioxide was used as gasifying agent. A pressurised thermogravimetric reactor was used for the experiments. The results show that the solid residue yield after pyrolysis/devolatilisation. increases with pressure and decreases with temperature. For coal, the gasification reactivity of the char increases by a factor of 3 to 4 when pressurising from 1 to 25 bar, for the `younger` fuels such as peat and wood, this effect is negligible. Several empirical, `engineering` equations are given which relate the fuel performance to the process parameters and the proximate and chemical analyses of the fuel. A pressure maximum was found at which a maximum gasification reactivity occurs, for practically all fuels, and depending on temperature. It is shown that this can be explained and modelled using a Langmuir-Hinshelwood model.
- Research Organization:
- Coal and Slurry Technology Association, Washington, DC (United States)
- OSTI ID:
- 585266
- Report Number(s):
- CONF-980309-PROC.; TRN: 98:001614-0008
- Resource Relation:
- Conference: 23. international technical conference on coal utilization and fuel systems, Clearwater, FL (United States), 9-13 Mar 1998; Other Information: PBD: 1998; Related Information: Is Part Of The proceedings of the 23rd International Technical Conference on Coal Utilization and Fuel Systems; Sakkestad, B.A. [ed.]; PB: 1143 p.
- Country of Publication:
- United States
- Language:
- English
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