The Building Tradesman Newspaper

Friday, December 02, 2011

Capturing coal dust makes for cleaner Presque Isle plant

By Marty Mulcahy, Editor

MARQUETTE – Wisconsin Energies imports about 1.6 million tons of coal every year at its Presque Isle Power Plant – but not quite all of it has made it to the plant’s boilers to be burned.

A small portion of coal dust escapes in the conveyor process at the plant, and it becomes an air pollutant and a fuel loss for WE Energies. Now, the building trades, along with design/engineering firm URS and constructor Day & Zimmerman, have installed equipment to make sure the fugitive coal dust stays in place.

“The goal is to make the Presque Isle plant cleaner, safer and more economical,” said Ron Geida, senior project manager for URS. This job is one of a number of projects that have been undertaken at the plant in the past few years, including emissions pollution control work and more recently, installation of equipment to allow the plant to burn other, more economical coals.

Located on five acres on the shore of Lake Superior, the coal-burning Presque Isle Power Plant is the fifth largest in Wisconsin Energy’s fleet. The first boilers at the plant came online in the mid-1950s. The facility currently has five operating steam boilers that were built in the 1970s and generate 431 megawatts of electricity.

The dust suppression and collection project and other work employed about 130 Hardhats at peak employment last summer. “We expect this will reduce airborne contamination that’s not from the stack,” said Gerald Robinson, the Presque Isle Power Plant’s maintenance manager. “And the plant will be cleaner, too.” The new equipment is slated to be online by the end of this year.

The process of cleaning the air of coal dust centers around the coal conveying system at the plant, which received upgrades in the processes of water treatment, dust collection and dust suppression. A new system will spray water in the airstream above the plant’s coal conveyor to collect coal dust, and the dampened dust will collect below the conveyor. That coal dust will then be collected, dried, and reused by being pressed into a 1/8-inch layer of “fine cake.” That coal-cake is then scraped into bins and put back into the coal pile. “In the end it’s a small amount of coal, but it’s kept out of the air,” said Robinson. Water that’s used in the process is also reclaimed.

The biggest challenge, said Day & Zimmerman Site Manager Tim Eaton, “has been to coordinate the efforts of everyone in a small space.” He said as many as 40 Hardhats have worked in the confines of the water treatment filter press area, working two shifts plus weekends. “That’s the tricky part of all of this, to install this equipment without affecting the day to day operations of the plant,” said Eaton. “It’s been amazing to see the work of the trades. We’ve absolutely been happy with the tradespeople here. It has truly been a joint team effort.”

The Presque Isle plant has been kept in operation during the process. It generates about 90 percent of the Upper Peninsula’s energy needs. “A lot of local people have been hired, and they take a lot of pride and interest in this plant,” said Eaton.

Despite all the construction and upgrade work the trades have enjoyed at the plant over the years, the Presque Isle facility’s future is in question. Last month, a blog on the WE Energies website disclosed that the utility is “beginning to consider options for the future of the Presque Isle Power Plant” because of costs associated with federal environmental regulations.

“We believe that new transmission is the best long-term option, and we are working with American Transmission Company to accelerate planning for new transmission facilities,” We Energies said in a statement. “No decision has been made on possible retirement of the plant, but current and potential federal environmental regulations make it necessary to consider the plant’s future. All of the options require considerable development time.”

The options include:

  • Retiring the plant,
  • Converting it from coal to natural gas,
  • Adding a new natural gas combined-cycle plant (coincident with retirement),
  • Adding new air quality controls.

“The decision must make economic sense for customers and ensure a robust and reliable power supply for the Upper Peninsula of Michigan,” WE Energies added.

LOCATED IN MARQUETTE, the Presque Isle Power Plant has been a major employer for building trades workers over the years, who have performed numerous modifications at the plant. The most recent was a coal dust collection project. But the days of the Upper Peninsula’s only major powerhouse may be numbered.

RIGGING AN AIR HOIST in the close confines of the Presque Isle Power Plant is Scott Staggs of Boilermakers Local 169. He’s employed by Day & Zimmerman.