Coal Ash Behavior in Reducing Environments
A series of tests have been conducted on two coals with the PDTF under various conditions (temperatures ranging from 1100{degree} to 1500{degree}C, pressures ranging from 50 to 100 psi, O/C ratios ranging from 1.0 to 2.0, and residence times ranging from 5 to 13 seconds). In summary, the results from the pressurized drop-tube furnace testing show differences in the inorganic transformations as a function of temperature residence time and coal type. The gas atmosphere and pressure did not have a visibly substantial effect on the results. It is expected that in a full-scale system that is oxygen- and/or air-blown, the initial atmosphere that the particles see will be similar regardless of amount of oxygen/air, but during the later stages the gas compositions will be significantly different. This would impact the vapor species, such as sodium, the most. The formation of calcium sulfide appears limited by high temperatures and longer residence times. This is primarily due to the instability of calcium sulfide at high temperatures. Iron sulfide, formed form the pyrite content in the coal, has a kinetically limited life in the high temperature regions of a gasification reactor. The iron sulfide decomposes to form metallic iron and iron aluminosilicates. The iron sulfides wet the surfaces of aluminosilicates during gasification to form sticky capture layers on the outside of the particles. Assuming the residence time within the reactor is short, some of the iron sulfide will exit without total decomposition, resulting in a sticky surface for deposition. Sodium, generally organically associated, appears to form sodium sulfide upon initial volatilization and quickly condenses on the surfaces of coalescing clay particles. The sulfide is not stable for long in the environment and results in the formation of sodium aluminosilicates.
- Research Organization:
- North Dakota Univ., Grand Forks, ND (United States). Energy and Environmental Research Center
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FC21-86MC10637
- OSTI ID:
- 10184212
- Report Number(s):
- DOE/MC/10637-93/C0204; CONF-9306148-18; ON: DE93019864; BR: 400408000/AA0505000
- Resource Relation:
- Conference: Coal-fired power systems `93: advances in IGCC and PFBC review meeting,Morgantown, WV (United States),28-30 Jun 1993; Other Information: PBD: [1993]
- Country of Publication:
- United States
- Language:
- English
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