Hayes Mechanical installed new ductwork to reverse the flow of gases going through an existing electrostatic precipitator utilizing air chain hoists, trolleys, MODULIFT® modular spreader beams and rigging supplied by Lifting Gear Hire.
THE SITUATION
In 2014, Hayes Mechanical was contracted by a Midwest power generation company to execute the “Hot to Cold Duct Conversion” project.
The project involved changing the flow of gases going through the precipitator in order to reduce the operating temperatures, which would in turn allow the mercury emissions to be reduced. According to Bill Bluis, the Vice President of Industrial Construction at Hayes Mechanical, the boiler flu gas duct modification project required the removal of over 625 linear feet of existing ductwork to be replaced with a new reconfigured design. All of which took place underneath the existing precipitator structure.
THE CHALLENGES
Right from the start of the project, a few challenges presented themselves. The main issue being the existing precipitator structure which was directly over the ductwork that required the work. This prohibited the use of a heavy lift crane.
Schedule constraints were also paramount to the success of the project. The plant faced closure if the work was not completed and the EPA emission parameters were not met by the end of the year. This also impacted the way the new ductwork would be built.
Bill added, “This was an outdoor project with the plant being located right on Lake Michigan, so weather was definitely a factor. Additionally we were working around an operating facility with the second boiler on line during the course of the work.”
THE SOLUTION
The biggest key in implementing their plan was developing concepts to perform the rigging and execution of the temporary rigging design, so they could work with the duct fabricator to manufacture 72 duct modules complete with insulation and lagging in certain sizes for the areas in which they were to be placed. The new duct modules were shipped by barge to the Waukegan Harbor, and later trucked a few miles down to the plant.
Bob Segiet the Project Manager and Site Construction Supervisor said, “We had to design and install an extensive system of monorails, trolleys, and chainfalls to demo out over 400 tons of the old duct and to maneuver the new modularized sections back in.”
“When we talk about the monorail system, it wasn’t one point of entry and one end point,” Bob continued. “We erected 60 tons of temporary structural steel and used upwards of 70 individual rigging pieces like the chainfalls and trolleys to manipulate a few different locations at the same time in order to move the duct work in and out of the structure. It couldn’t be done one piece at a time. It would’ve taken too long.”
THE RESULT
The project was finished on time and the unit was released back to the customer ahead of schedule. From an engineering standpoint, the goal was to reduce the operating temperatures of the precipitator by 350 degrees F. Due to the efforts exerted by Bill and Bob’s team, they were able to accomplish their endeavor and the project was deemed a success. By reducing the operating temperatures of the precipitator, it lowered the mercury emissions present in the facility and allowed the customer’s facility to meet the EPA standards required and continue operation.
Despite the challenges involved, it was clear to Bob and Bill just what was needed to ensure a successful project.
“We involved Lifting Gear Hire’s local representative early on,” Bill said. “We knew the quantities of the rigging we would be using were a little more than what they were used to seeing on a power plant job from us. We worked with the local rep to make sure we had the right pieces and quantities available right from the start of the job. Of course, there were other venders available, but what sold it for us was obviously the quality of the equipment. With as many pieces as we needed, we knew we’d be getting the commitment and dedication that we needed for our equipment from Lifting Gear Hire. Not to mention, if we had a piece of equipment go down, we’d get a spare or a replacement in less than 12 hours.”
“We have worked with LGH for many years,” Bob added. “Because the reliability and condition of the equipment, we were very confident that when the equipment came out, it was going to be rebuilt, inspected and ready to go. Also, LGH provided all the documentation we needed for the lift plans as well. This made it very easy for us to get right into the project.”
“There’s always potential for a piece to go down,” Bob concluded. “When you’re using 46 chainfalls it’s a real possibility. However, LGH gave us spares, wrapped them in plastic, and told us if they’re not used, then return them and you will not be charged. That’s quality of service I’ve never seen before.”
LGH Equipment Used:
2, 3 and 6 ton air chain hoists
Associated trolleys
4,000 # air tuggers
Modular spreader beams
Learn more on this case study here.
