TY - GEN
T1 - Could biomass-fueled boilers be operated at higher steam temperatures? 3. Initial analysis of costs and benefits
AU - Sandy Sharp, W. B.A.
AU - Jim Frederick, W. J.
AU - Keiser, James R.
AU - Singbeil, Douglas L.
N1 - Publisher Copyright:
Copyright © (2013) by the TAPPI Press.
PY - 2013
Y1 - 2013
N2 - The efficiencies of biomass-fueled power plants are much lower than those of coal-fueled plants because they restrict their exit steam temperatures to inhibit fireside corrosion of superheater tubes. However, restricting the temperature of a given mass of steam produced by a biomass boiler decreases the amount of power that can be generated from this steam in the turbine generator. This paper examines the relationship between the temperature of superheated steam produced by a boiler and the quantity of power that it can generate. The thermodynamic basis for this relationship is presented and the value of the additional power that could be generated by operating with higher superheated steam temperatures is estimated. Calculations are presented for five plants that produce both steam and power. Two are powered by black liquor recovery boilers and three by wood-fired boilers. Steam generation parameters for these plants were supplied by industrial partners. Calculations using thermodynamics-based plant simulation software show that the value of the increased power that could be generated in these units by increasing superheated steam temperatures 100 Celsius degrees above current operating conditions ranges between $2,410,000 and $11,180,000 per year. The costs and benefits of achieving higher superheated steam conditions in an individual boiler depend on local plant conditions and the price of power. However, the magnitude of the increased power that can be generated by increasing superheated steam temperatures is so great that it appears to justify the cost of corrosion-mitigation methods such as installing corrosion-resistant materials costing far more than current superheater alloys, redesigning biomass-fueled boilers to remove the superheater from the flue gas path, or adding chemicals to remove corrosive constituents from the flue gas. The most economic pathways to higher steam temperatures will very likely involve combinations of these methods. Particularly attractive approaches include installing more corrosion-resistant alloys in the hottest superheater locations, and relocating the superheater from the flue gas path to an externally-fired location or to the loop seal of a circulating fluidized bed boiler.
AB - The efficiencies of biomass-fueled power plants are much lower than those of coal-fueled plants because they restrict their exit steam temperatures to inhibit fireside corrosion of superheater tubes. However, restricting the temperature of a given mass of steam produced by a biomass boiler decreases the amount of power that can be generated from this steam in the turbine generator. This paper examines the relationship between the temperature of superheated steam produced by a boiler and the quantity of power that it can generate. The thermodynamic basis for this relationship is presented and the value of the additional power that could be generated by operating with higher superheated steam temperatures is estimated. Calculations are presented for five plants that produce both steam and power. Two are powered by black liquor recovery boilers and three by wood-fired boilers. Steam generation parameters for these plants were supplied by industrial partners. Calculations using thermodynamics-based plant simulation software show that the value of the increased power that could be generated in these units by increasing superheated steam temperatures 100 Celsius degrees above current operating conditions ranges between $2,410,000 and $11,180,000 per year. The costs and benefits of achieving higher superheated steam conditions in an individual boiler depend on local plant conditions and the price of power. However, the magnitude of the increased power that can be generated by increasing superheated steam temperatures is so great that it appears to justify the cost of corrosion-mitigation methods such as installing corrosion-resistant materials costing far more than current superheater alloys, redesigning biomass-fueled boilers to remove the superheater from the flue gas path, or adding chemicals to remove corrosive constituents from the flue gas. The most economic pathways to higher steam temperatures will very likely involve combinations of these methods. Particularly attractive approaches include installing more corrosion-resistant alloys in the hottest superheater locations, and relocating the superheater from the flue gas path to an externally-fired location or to the loop seal of a circulating fluidized bed boiler.
UR - http://www.scopus.com/inward/record.url?scp=84943591206&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:84943591206
T3 - 2013 PEERS Conference, Co-located with the 2013 International Bioenergy and Bioproducts Conference
SP - 1126
EP - 1142
BT - 2013 PEERS Conference, Co-located with the 2013 International Bioenergy and Bioproducts Conference
PB - TAPPI Press
T2 - 2013 PEERS Conference, Co-located with the 2013 International Bioenergy and Bioproducts Conference
Y2 - 15 September 2013 through 20 September 2013
ER -