Elbowroom
Chalmette refinery erects hydrotreater unit on half-acre site

By Sam Barnes

Installation of a $95 million hydrotreater unit at a small Chalmette refinery has been much more than a small task.

The unit will enable the 89-year-old refinery, owned by Chalmette Refining LLC, to comply with an Environmental Protection Agency requirement to lower the sulfur content in gasoline. Chalmette Refining is a joint venture between ExxonMobil and Venezuela's state oil company, Petroleos de Venezuela.

Within the unit, ExxonMobil Research and Engineering Co.'s SCANfining gasoline sulfur reduction process will selectively remove sulfur while minimizing octane loss.

Before the project is completed this fall, construction manager Kellogg, Brown & Root of Houston and its subcontractors must contend with a constricted half-acre jobsite and a diminutive staging area.

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"The most difficult design task, initially, was finding enough real estate for the unit," said Joseph Kazda, project execution leader with Chalmette Refining. "We had to find a way to minimize the size of the unit to squeeze it into the existing space, while complying with distance requirements for the facility."

Engineers determined that three buildings and a nitrogen plant on the perimeter of the plant could be demolished to create the half-acre space necessary to support the unit.

"An existing warehouse within the refinery was transformed into office space so personnel could be relocated from the buildings," Kazda added.

While the project team is fortunate to have a jobsite on the outskirts of the plant with its own dedicated entrance, the site's small footprint leaves little area for material laydown and prep.

"When subcontractors such as James Construction Group of New Orleans or Harmony Corp. of Baton Rouge need to bring in heavy equipment or lay a vessel down, there isn't a lot of extra space to go around," Kazda said. To remedy the problem, KBR leased laydown yards near the refinery for its subcontractors.

Tom Jensen, KBR's senior project manager, said the project's challenges have also been alleviated by KBR's ability to utilize "best practices" from previous projects.

"KBR completed three similar projects for ExxonMobil last year," Jensen added. "Because of that we've been able to utilize their lessons learned, roll over some of the people from those projects and do whatever we could to benefit from those experiences."

He said the result has been less "re-work" in the field.

To connect the new unit with the existing plant, Harmony Corp. and Meraux-based Lou-Con performed 134 tie-ins as part of the offsite phase of the project.

"We reinforced existing piperacks with new foundations and steel to support additional pipe and brought the connections up to the battery limits of the new unit," said Lester Barback, vice president of construction for Harmony Corp.

Extensive planning was necessary to ensure Harmony's work did not interfere with existing refinery operations.

"Our schedule required that certain sections be done by certain dates," Barback added. "We had to turn them over when the refinery needed them. There wasn't any flexibility."

The offsite work was finished in mid summer.

"Our strategy was to get the offsite work finished early so that everything would be confined to the jobsite battery limits," said Troy Carter III, operations representative with Chalmette Refining. "That helped us control the schedule better."

Work within the new unit began in Spring 2003 when Professional Construction Services of New Orleans excavated the site.

"When you have a site with a small footprint and a lot of foundations, you don't want to have to dig down for each individual foundation," said Conrad Bourg, Industrial Division manager for James Construction Group. "It makes more sense to 'bathtub' the entire site, then build foundations and backfill." About 7,000 cu. yds. of fill material was needed for backfill.

It was difficult to locate underground obstructions during the excavation, given the age of the refinery.

"We used hydro-trenching to dig a trench around the perimeter of the site with high pressure water," Jensen said. "We identified how many lines were there and how many of those actually matched to the drawings."

After removal of existing pipes and excavation, Berkel & Co. of Bonner Springs, Kan., drilled 600 55-ft.-deep positive displacement auger piles. James Construction Group then began installing high-density polyethylene and carbon steel pipe and building concrete slab foundations.

Bourg said the most complicated foundations included some 3-ft.-deep concrete slabs and two elevated tabletop foundations for the unit reactors. There also was a large sump on the southwest corner of the site to deal with.

"Ultimately, we placed about 3,300 cu. yds. of concrete for foundations and site paving and installed about 5,000 ft. of pipe," Bourg said.

Harmony and Nichols Construction Corp. of Baton Rouge began installing vessels and equipment within the hydrotreater unit after most of James Construction's work and the unit's main pipe rack by Group Contractors of Baton Rouge had been completed.

"That helped us stay out of each other's way, since about 250 workers were working out here at peak," Barback added. Having the entire site paved also minimized the impact of inclement weather on the Harmony crew.

A furnace stack was the tallest piece of equipment to be erected within the unit and was delivered to the site in two sections, then welded, lifted and placed.

When space allowed, other columns and vessels were placed on the ground so that piping, insulation and electrical and instrumentation work - by ISC of Baton Rouge -

could be performed prior to erection.

Many of the heavy lifts were performed on weekends because of lighter equipment traffic and fewer people working within the refinery.

"We expect to finish the project in September, then begin unit start-up in October," Carter said. "That's the deadline we established in the beginning and so far we're still on that schedule." About 400,000 labor hours will have been worked by project's end.

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For more information on ExxonMobil's SCANfining technology, go to: http://www.prod.exxonmobil.com/refiningtechnologies/fuels/mn_scanfining.html