Cladding AEB Amsterdam

Introduction

The initial start-up of the plant was in March 2007. Both boilers were fitted with Inconel® 625 weld overlay (approximately 4500m² in total), in the complete 1^st pass (also behind the refractory), the 2^nd pass, the roof and further down the boiler. During an inspection approximately 8 months later thinning of the original Inconel® 625 weld overlay (original thickness not disclosed to AmStar) had been observed. Corrosion (pitting) to a higher degree than expected was observed in the 1^st pass from the refractory up, and on the roof. AEB estimates that if the corrosion continues at this rate the live expectancy of the membrane wall parts involved will be 4 - 5 years maximum.

The process conditions are (as far as known) within the WtE business considered as extreme. The boilers currently operate at 139 Bar (steam pressure) and 450°C (saturated steam temperature) with a 33% steam efficiency. AEB's goal is to reach 40% steam efficiency in the near future. Furthermore the concentration of hydrochloric acid (HCl) present in the exhaust gasses, is far higher than in other WtE installations.

AmStar Surface Technology was requested to apply AmS 888 cladding in the Waste to Energy boiler utilizing HVCC (High Velocity Continuous Combustion) technology. The AmS 888 series alloys are modified Inconel based materials.

The shutdown took place in November 2008 and several companies installed their materials in different locations in the boiler. The other contractors involved in the application used Alloy 686, 622 and 686 CMT (cold metal transfer). As the cladding application was scheduled on the outage critical path, every effort was made to minimize the project timeline. The coating installation was a success and completed in accordance with the quality assurance and control procedures.