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

Category

Description

Repair or Replacement Needs

Frequency

Cost

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

Fans

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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