Portage, Wisconsin

Unit 2 SCR Upgrade Project

Client / Owner

Alliant Energy, Wisconsin Public Service, and Madison Gas and Electric

Architect / Engineer

Sargent & Lundy LLC




Graycor Industrial

Project Scope

GSL, a joint venture between Sargent & Lundy and Graycor Industrial, is near completion of upgrading Unit 2 at the Columbia Energy Center. The environmental project called for GSL to provide engineering, procurement and construction (EPC) services to build a selective catalytic reduction (SCR) system with direct injection of aqueous ammonia to control the unit’s nitrogen oxide emissions. The air-quality control system (AQCS) project also included upgrades or modifications to existing plant systems to support operation of the new SCR equipment.

Project Scope: Engineering, procurement, construction, commissioning/startup and performance testing of a turnkey SCR system including installation of deep foundations, SCR and associated ancillary foundations, structural steel/platforms, SCR reactor, interconnecting ductwork, expansion joints, and dampers, boiler modifications, balance-of-plant (BOP) equipment and process equipment including air compressors and ancillary equipment, 45,000-gallon ammonia storage tanks, ammonia unloading, supply, and direct injection skids, shielding and atomizing air skids, sonic horns and air sweep cleaning equipment, all piping, tubing, instrumentation, and electrical installations associated with the BOP and SCR systems.

Because the project was performed within a confined work site area with vertical construction taking place above operating equipment, material management and coordination were critical to the project’s safe and efficient execution. In addition, essential pre-outage work took place prior to the seven-week construction outage tie-in.

Self-perform work included demolition, structural steel, ductwork and SCR assembly/erection, piping, and mechanical equipment installation.