- Boswell Energy Center Unit 4 Retrofit
Burns & McDonnell provided design, procurement, construction management and startup services for Minnesota Power’s second-largest coal facility, Boswell Energy Center.
The Unit 4 retrofit consisted of upgrading, replacing or installing emission control equipment to reduce air emissions of sulfur dioxide (SO2), particulate matter (fly ash) and mercury. The project included procurement, construction management and startup of:
- Semi-dry flue gas desulfurization (FGD) system
- Lime receiving, handling, storage and hydration systems
- FGD byproduct handling and storage systems
- Flue gas system (draft fans, ductwork)
- Pulse jet fabric filter
- Waste handling system
- Waste disposal
- Activated carbon storage and injection system
- Detailed design
- Construction management
Boswell Unit 4 is a pulverized coal-fired combustion engineering tangentially fired steam generator. It was commissioned in 1980 and is rated at 652 MW (gross).
Boswell Unit 4 employs low nitrogen oxide (NOx) burners and separated OFA (SOFA) for NOx control, a venturi scrubber for particulate control, and a spray tower absorber for SO2 control. A small portion of the flue gas (2 percent to 5 percent) bypasses the venturi scrubber and spray tower absorber. This bypass stream is treated by an electrostatic precipitator (ESP) for particulate control before being blended with the remainder of the flue gas, where it acts to reheat the flue gas treated by the venturi scrubber and spray tower absorber.
- Semi-dry FGD system
- PJFF system