Fluidized Bed Boiler Tubes THE CHALLENGE • Original unit 10 bubbling fluidized bed boiler tubes supplied with 1mm induction fused 15Cr, 4.5Fe, 4Si, balance Ni spray coating. • Uninterrupted service life expected five years. • After two years service, unit experienced tube leaks due to spray coating erosion failures. Kennametal infiltration brazed cladding measured by eddy-current revealed thickness loss, in a localized area, in line with a catalyst injection nozzle at 0.002; remaining clad area had no measurable coating thickness loss. • Reoccurring forced outages due to tube leaks. • Spray coating failure due to poor erosion resistance, and coating disbonding, exposing tube base material. T H E R E S U LT P L A N T S P E CIF I C AT I O N S • Produces 9 billion kilowatt-hours of electricity annually. • Consumes 12,000 tons of blended coal daily. • Three alternative tube protection materials installed in unit 10 for evaluations: high chrome weld overlay 0.140" thick, thermal spray 0.040" thick, and Kennametal infiltration brazed cladding 0.030" thick. • Two-year service exposure resulted in coating failure of the weld overlay and the thermal spray required the removal of test sections. • 10 coal-fired boilers. • 160MW Unit 10 was the nation’s first commercial scale atmospheric fluidized bed combustion boiler. • Unit 10 predominantly burns high sulfur coal from Illinois. • Kennametal infiltration brazed cladding measured by eddy-current revealed thickness loss, in a localized area, in line with a catalyst injection nozzle at 0.002; remaining clad area had no measurable coating thickness loss. • Fluidized bed tube life estimated at 15+ years of service life. • Evaporator area for unit 10 utilizes SA210-1, 57.15mm OD x 5.59mm wall internal rifled tube. • Units 1–9 utilize low NOx burners. • Unit 1 is evaluating selective non-catalytic reduction technology. Kennametal Inc. 501 Park East Boulevard New Albany, IN 47150 USA ©2014 Kennametal Inc. l All rights reserved. l B-14-04187EN