Key issues when cofiring biomass with coal in PC boilers
Cofiring biomass with coal in PC-fired boilers represents a near-term, low-risk, low-cost option for reducing greenhouse gas emissions, increasing renewable energy generation, and increasing sustainability of energy supplies from power production. Economically, cofiring competes favorably with other renewable options, although generally not so favorably as to reduce overall cost of fuel. This presentation focuses on five key fireside issues associated with cofiring: ash deposition, NOx production, corrosion, ash disposal, and carbon burnout. Biomass ash deposition rates and NOx emissions can either exceed or be less than those of coal, depending on the type of biomass used. SOx emissions are nearly always reduced when cofiring biomass with coal. The potential for chlorine-based, high-temperature corrosion is seen to be less significant for a biomass-coal blend than for pure biomass fuels in most cases, but may not always be negligible. Fly ash generated from wood cofiring is technically suitable for cement production, although it is precluded from such application in ASTM specifications. Fly ash from many herbaceous materials is less suitable for cement production. Biomass particles much larger than coal particles can be consumed in a PC boiler, but at sizes of 1/8 inch or larger there is increased chance of incomplete combustion. Significant carbon in flyash problems are not anticipated until initial particle sizes exceed 1/4 inch for many practical systems. Specific guidelines are suggested in each area in terms of expected behavior and best-practice operation. Prudent choices of fuels, boiler design, and boiler operation should lead to little or no fireside problems during cofiring. Less prudent choices can lead to significant boiler damage and operational costs.
- Research Organization:
- Sandia National Lab., Livermore, CA (US)
- OSTI ID:
- 20082212
- Resource Relation:
- Conference: Sixteenth Annual International Pittsburgh Coal Conference, Pittsburgh, PA (US), 10/11/1999--10/15/1999; Other Information: 1 CD-ROM. Operating systems required: Windows 95/98; Windows 3.X, Macintosh; PBD: 1999; Related Information: In: Sixteenth annual international Pittsburgh Coal Conference: Proceedings, [2000] pages.
- Country of Publication:
- United States
- Language:
- English
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