Bolted RTP Storage Silo Right Fit for Power Plant

Empire District Electric Co. is undergoing an environmental retrofit project at its Asbury Power Plant in Asbury, MO. As part of the environmental improvement process, the FGD ByProduct would be conveyed into a storage silo and then processed using equipment located in the skirt of the storage silo. Tank Connection was chosen for the design, fabrication, and installation of the bolted RTP (rolled, tapered panel) storage silo, and completed the installation testing in May 2014.
     The FGD ByProduct silo is a 32.7-ft-diam by 96.2-ft-tall dry bulk storage silo of bolted steel construction. This is a skirted silo with a hopper clearance of 30 ft, and a hopper slope of 60 degrees terminating in a 10-ft-diam outlet. The skirt has drive thru reinforced openings at 16 ft wide by 16 ft tall, and a skirt equipment platform at 18 ft. The working capacity of the silo is 42,500 cu ft, or over 1900 tons of material. The silo was fabricated from over 170 tons of steel.
     The FGD ByProduct is conveyed into the TC silo through filter separators located and supported by the silo roof. TC utilized a unique “under deck” roof structure with supporting columns penetrating up through the roof deck to resolve the filter separator loads. The use of the “under deck” support allowed for the silo roof deck to remain unencumbered by the typical external supporting structure.
     Unloading the silo occurred through the use of a 60-degree hopper with a 10-ft-diam fluidized flat bottom outlet, which was located 30 ft above grade. Unique to this design was the specification requirement that the hopper outlet flange be designed for impact loading, by which TC worked with the project engineer to quantify an acceptable load value and designed accordingly.
     The fluidized FGD ByProduct was then processed by mixer/unloaders located on an elevated platform in the skirt of the silo. The elevated skirt platform consisted of a reinforced concrete slab placed inside the silo at 18 ft above grade. While Tank Connection routinely designs, fabricates, and installs elevated full-diameter concrete platforms in silo skirts, the scope of work on this project was limited to the design, fabrication, and installation of the support steel required for the concrete slab, and all of the small components necessary to place the slab correctly.  
     Equipment access and maintenance – both inside the silo skirt and exterior to the silo and roof - was another project requirement. Tank Connection provided multiple ladders, access platforms, and an external spiral stairway with platforms to meet the client’s need. A jib crane, monorail beam supports, and the numerous access points provided the operations personnel the ability to safely maintain the equipment.
     Tank Connection and the project engineer engaged in a rigorous engineering general arrangement process to ensure that the client and project needs would be met. Coordination across multiple vendors and disciplines is no easy task, but is critical to minimizing field issues during construction or functional issues during startup and operation. This early work further pays dividends during the construction phase, enabling full productivity where the focus can be on safety and quality rather than conflicts and RFIs. Tank Connection provided productive and accurate communication, maintained a project specific schedule, and worked to solve problems throughout the entire project. The Asbury Environmental Retrofit project FGD ByProduct silo was executed just as it was planned, on scope, on budget, and on schedule.
     Tank Connection utilizes a RTP panel bolted silo that provides the project three notable benefits versus the field-welded silos typical in power plant applications: shop coating system; reduced installation duration; efficiency. Fusion 5000 FBE, a powder coating system developed for bolted dry bulk storage silos, is one of the key components to create a long life lasting solution. This proprietary coating technique allows superior flow promotion and abrasion resistant qualities, which is important for storing the FGD ByProduct.
     Tank Connection supplies dry bulk and liquid storage tanks and silos utilized in the power industry. Typical applications include lime, limestone, fly ash, bottom ash, process water, industrial liquids, and coal storage. Tank Connection offers all four types of steel storage tanks, including bolted RTP, field-weld, shop-weld, and hybrid tank construction. For more information, visit www.tankconnection.com.

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