Design and Construction of Fly Ash Silo with Inverted Cone

A coal and biomass power plant was built at Maasvlakte near Rotterdam in the Netherlands. For the storage of fly ash which is a residual product of the coal combustion process, a 24 m diameter reinforced and prestressed concrete silo having a height of 65 m was designed. The silo has a central inverted cone composed of precast concrete elements which forces the fly ash to be discharged from eight openings around the perimeter of the silo. This paper presents the process of designing the foundation, the cylinder wall and the central cone and discusses the engineering challenges. It deals with the characterization of the load cases resulting from filling and discharging the silo, and explains the way thermal loads resulting from the high-temperature fly ash were allowed for in the analysis of the structure. Finally, it summarizes the main issues regarding the construction of the silo structure.