Durr Mechanical had to build and transport a 4,000-ton generator over 150 miles.
By Alan Dorich
Some may overlook the transportation aspects of a power generation project, but those elements recently proved critical for Durr Mechanical Construction Inc. The contractor was tasked with constructing a massive heat recovery steam generator (HRSG) for the PSEG Fossil LLC Sewaren Generation Station under construction in Woodbridge, N.J.
But the company also had to transport the 4,000-ton, 126-foot-tall generator 150 miles from Port of Coeymans, N.Y., to Woodbridge. The plant, Vice President Paul Thompson explains, is being built on a small footprint that prevented all components from being constructed on site at once.
The project also has a very aggressive, tight schedule, which made things even more complex. “The only way we could complete the schedule was by building all the components at once,” he says, adding that the entire plant is built around the HRSG, its single largest component.
Construction of the HRSG is not a new experience for Durr Mechanical. “We’ve built projects as large as that before,” Paul Thompson says. “What’s unique about this is it was built in a remote location, then barged to the site.”
ConstructionManager Steven Thompson notes that the HRSG operates in the exact same function as a boiler andthe power is generated by two electric generators driven by a combustion turbine and a steam turbine.
The HSRG runs on the waste heat of the combustion turbine instead of burning its own fuel. It then uses that heat to produce the steam to drive the steam turbine. “It’s recycling the waste heat and using it to produce more power,” he says.
The Sewaren plant will plug into the HRSG, which will provide it with efficiencies when it opens this summer.
For example, thanks to the generator, emissions are reduced substantially, compared to those emitted by “an equivalent, conventional power plant,” Paul Thompson says. In addition to the environmental benefits in reducing the emission of greenhouse gases, the plant is much more thermally efficient than the plant it is replacing, resulting in less fuel being needed to generate the same MW, leading to a lower cost/MW.
The process of transporting the HRSG took Durr Mechanical one-and-a-half days, but the company spent eight months planning and preparing for the move. This included winning approval from the United States Coast Guard and the US Army Corps of Engineers.
Durr Mechanical also hired “a permitting consultant who was essentially the conductor for the permitting process,” Steven Thompson recalls, noting that the path to permits can be quite involved.
The company also prepared for the journey by taking into account wind and wave forces, as well as possible obstructions during the voyage. Through a study, Durr Mechanical learned that the middle of the Mid-Hudson Bridge provided a low point on the Hudson River, with less than nine feet of clearance. “We built the HRSG just low enough to pass under [it],” Steven Thompson says.
Making the Move
In August 2017, the contractor moved the HRSG with self-propelled modular transporters (SPMT’s) similar to those used by NASA to move the Space Shuttle. “[We also] designed a substructure to the HRSG that would allow these transports to drive under it,” Thompson describes.
The SPMT’s slowly and carefully rolled over a ramp onto a barge as they carried the HRSG. “Once it was on the barge, we raised a sigh of relief,” Paul Thompson recalls.
But Durr Mechanical’s careful work did not end there. Instead, the company had to make sure it was placed exactly where it needed to be on the barge, and was tied down and secured in the correct way.
After it was finished, the barge, which was pulled by three tugboats, transported the HRSG to the Sewaren site, This process earned Durr attention from news outlets as well as The Wall Street Journaland USA TODAY.
“These means and methods have been used before to bring stuff that was manufactured overseas into the United States,” Thompson notes. “But it’s never been done on this scale in the United States.”
When Durr Mechanical arrived at the project site, it had to complete more complex work, which essentially required it to “do the loading process in reverse,” Thompson recalls. The company first had to re-ballast the barge and install new bridge ramps to get the HRSG onshore.
Durr Mechanical then drove the generator across the project site slowly to the anchor bolts and lowered it down. However, “There was very little room for error when placing the things on the anchor bolts at Sewaren,” he recalls, noting that the company only had an eighth of an inch in tolerance.
After bolting and welding the HRSG in place, the piping and electrical power and controlsremained to be connected. “It’s a pretty involved process,” he says, noting that process lasted two months.
Aiming for Excellence
Based in New York City, Durr Mechanical has established itself as one of the leading mechanical contractors in the Northeast area. Founder Bob Durr Sr. started the company in 1985, with a focus on quality and integrity.
Since then, Durr Mechanical says it has dedicated itself to excellent workmanship, on-time completion, budget delivery and high safety standards. “Our customers know that when you need a job done right, you come to Durr Mechanical Construction,” it says.
“Our mission is to provide our customers in the power, process and commercial HVAC markets with services of the highest quality and integrity at a fair profit,” the company continues. “We will provide our employees the opportunity to grow to their fullest potential through training and mentoring as they contribute to the success of our family business while working toward our goal of safety excellence.”
The company has focused on expanding its footprint outside the New York City area, which included the formation of its Special Services Group. The division focuses on maintenance work and more modestly sized projects. “They’re very busy,” Paul Thompson says. “They ... don’t really get any glamour projects.”
He predicts more work ahead for Durr Mechanical at the Coeymans site. “We’re in the process of developing a couple very similar projects that we will build in the same location,” he says.
A Constant Focus
Durr Mechanical Construction Inc. has made worker safety of paramount importance. “We are committed to providing a secure work environment at all times, and employ strict standards, rigorous employee training and regular review of safety procedures to protect our employees,” it says.
The company’s site management and field supervisors plan safety into all of its tasks. “No details is left to chance, particularly with the heavy lift operations required to set turbine equipment, generators, HRSG modules, and many other types of power and process equipment,” it says.
This constant vigilance, Durr Mechanical notes, safeguards workers from injuries and promotes higher productivity and makes it more competitive. “In fact, we routinely consult our insurance company’s safety engineer or an industry professional tor review our methods and make safety recommendations,” it says.