By Paul Fisher
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19 Apr, 2022
The East Bay Municipal Utility District (EBMUD) Wastewater Treatment Plant, located on the eastern shore of San Francisco Bay, provides service for an estimated 740,000 people in the greater Oakland, California area. In addition to traditional wastewater treatment, the plant also collects and treats solid waste from Bay Area food and animal processing facilities, restaurants, and wineries, diverting this waste stream away from landfills. The methane gas that is generated from the decomposition of this solid waste is then used internally as a renewable source of energy to help supply the treatment plant’s energy needs. When EBMUD began looking for a way to upgrade the failing brick refractory lining in their emergency digester gas flare structure, they turned to TFL, Incorporated. TFL developed an innovative precast refractory shape system that would offer dependable performance, structural integrity, and ease of installation. The unique system of floating wall panels is held in place using tongue-and-groove tieback shapes, bolted to the existing concrete structure. The individual panels in the system can absorb thermal and mechanical stresses independently. Given the location, potential seismic loading was also considered in the development of the system. The existing flare containment building is an oval-shaped concrete structure, with inside dimensions of 17’ wide by 47’ long. The refractory lined upper section of the structure is just over 21’ tall. The refractory wall thickness is 4-1/2”. A 2” air gap between the refractory wall and the concrete wall allows for airflow and ventilation. The refractory wall system consists of 514 precast shapes of four basic types, all manufactured in TFL’s Houston, Texas facility. The shapes were cast using Plicast HyMOR 3000 KK, a low-cement castable refractory manufactured by Plibrico Company. Stainless steel needle fibers were used for added reinforcement and to improve resistance to thermal shock and cracking. The shapes were fired to 1250o F prior to shipment, optimizing strengths and allowing the flare structure to be immediately operational, without the need for a field dry out of the refractory. NTK Construction, Inc. of San Francisco, California, was the installation contractor for EBMUD.