Rothschild recap

Craig Timm, Manager, Public Affairs

The skyline of Rothschild, Wisconsin, changed dramatically last summer as work progresses on the 50 megawatt biomass-fueled power cogeneration plant being constructed on site at the Domtar mill. Everything is geared toward a fall 2013 commercial operation and production start.

This new power cogeneration plant project, a joint effort between WE Energies and Domtar which was announced in September 2009, will virtually eliminate the facility’s use of fossil fuels and instead use harvested forest residues and waste wood.

Structural progress

The structural steel of the boiler building (the tallest building on site) was topped out in February. The steel framework is mostly complete for the other main buildings on the site, including the turbine generator building, fuel storage building and cooling tower structure.

The biomass boiler, the largest piece of equipment at the facility, is currently being assembled inside the steel framework of the 190-foot (58m) boiler building. Two cranes were required to lift the boiler’s steam drum and set it into place. It will take approximately one year to assemble all the components of the circulating fluid bed boiler, which will burn about 500,000 tons (454,500 metric tons) of biomass fuel annually.

Coming this fall

General Electric is manufacturing the steam turbine/generator. It is expected to arrive on site in early October. When in use, approximately 200,000 pounds (90,718 kg) of steam per hour will be extracted for use in the mill’s papermaking process. Condenser cooling will be provided by an on-site cooling tower located on the east bank of the Wisconsin River. The cooling tower will be equipped with a special abatement technology designed to eliminate visible water vapor plumes.

The plant will have a natural gas backup boiler to ensure steam delivery to the paper mill at times when the biomass boiler is down for maintenance. The natural gas boiler, manufactured by Cleaver-Brooks in Lincoln, Nebraska, was delivered to the site in June. The cargo traveled across the Midwest for nearly a week on a 225-foot (69m) semitrailer. Once the installation project is complete, Domtar will permanently shut down its current boilers, and the biomass and natural gas boilers will supply steam to the mill.

The biomass fuel storage building, located on the south end of the mill’s property, measures 160 feet wide by 435 feet long by 65 feet high (49.2m X 133.8m X 20m) and will hold up to five days of fuel for the plant. It will be equipped with a portal reclaimer to collect fuel from the pile to just above the floor and regularly turn over inventory.

International flavor

Vendors from around the world and many close to home are playing an important role in the construction process. Borregaard/LignoTech, a lignin-products manufacturer located on Domtar’s property in Rothschild, supplied a chemical admixture to the ready-mix concrete used for the foundation of the biomass storage building. Admixtures play an important role in controlling strength, set rate, viscosity and other properties in ready mix concrete. They allow concrete to deliver precise characteristics required for each project.

Other Wisconsin vendors have also provided a variety of materials and services, including structural steel, concrete, rebar, lumber, piping, excavating, plumbing, electrical and engineering. On any given day, more than 150 workers, many from north central Wisconsin, participate in building the facility. Work has progressed in a safe manner, with more than 150,000 injury-free hours.

A sustainable future

The plant will be fueled with sustainably harvested forest residues and waste wood. Local independent contractors will secure waste wood from area forests and transport it to the mill site. Studies verify that area forests within a 75-mile (121 km) radius of the Domtar mill can support the power plant, and the project could provide a significant opportunity to further improve forest health.

As the skyline changes in Rothschild, it is great news for Domtar.