TABLE D-1 Summary of Common Repair and Replacement Activities, Frequencies, and Cost for Coal-Fired Electric Utility Power Plants



Repair or Replacement Needs



Boiler tub eassemblies

Rows or bundles of heat exchanger tubes

Wear and periodic failure attributable to erosion, corrosion, and temperature/pressure-related stresses, leading to outcomes such as leaks, forced outages, loss of reliability, and potential for substantial boiler failure

Considered to be common; entire tube assemblies replaced at nearly every boiler, as early as 5 years after commercial operation

Up to $40/kW to replace tube assemblies on a large boilerand potentially more on a smaller boiler


Forced draft fans push combustion air into the furnace; induced draft fans pull flue gas from the furnace; a balanced draft system has both; other typical fans include primary air fans for pneumatic transport of pulverized coal and flue gas recirculation fans for NOx control

Erosion and cyclic fatigue; fans exposed to flue gases often subject to higher temperatures as well as erosive ash and corrosive acid gases. Reduced effectiveness of fan reduces plant output; failure leads to shutdown

Fans have been substantially replaced in over 70% of units

Replacement of a large fan can cost up to $20/kW; retrofitting a balanced draft system in place of a forced draft system can cost $70/kW

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