Ash deposition during Illinois [number sign]6 coal proof-of-concept testing at the Coal Fired Flow Facility
Ash deposition is a phenomenon that occurs when a fossil fuel containing an inorganic impurity (ash) is burned and the hot combustion gases (flue gas) pass over cooled heat transfer surfaces. The cooling medium can be air, water, boiling water, or steam. Investigators have traditionally identified two general categories of ash deposition in steam generators: slogging and fouling. Slogging is usually defined as fused deposits that form on furnace walls and other surfaces exposed to predominantly radiant heat. Fouling is defined as deposition on convection tube banks, especially on superheaters and reheaters and can refer to both those which are bonded to tube surfaces and non-bonded (loose) deposits. Boiler designers must be able to ensure that slagging does not occur on secondary superheater tubes in conventional boilers. For MHD boilers, this problem must be considered for superheater and air heater. Molten deposits can be a problem at temperatures as low as 1636[degrees]F, the melting point of potassium carbonate. Ash deposition is important for several reasons. The most important is that deposition retards heat transfer and, therefore, will affect boiler designs which must account for the extent of the deposition expected. If not well controlled, deposition can elevate the exit gas temperatures, reduce heat transfer efficiency, reduce steam generator capacity, and in some extreme cases block gas passages which reduces boiler availability. In all cases, even if it is well controlled, ash deposition results in higher capital and operating costs. However, fuels containing high amounts of ash usually have lower costs which tend to compensate for the costs associated with ash deposition.
- Research Organization:
- Tennessee Univ., Tullahoma, TN (United States). Space Inst.
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC02-79ET10815
- OSTI ID:
- 6571856
- Report Number(s):
- DOE/ET/10815-200; UTSI-92-10; ON: DE93013402
- Country of Publication:
- United States
- Language:
- English
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300102* - MHD Generators- Performance & Testing