Using 3-D modeling keeps boiler project moving
When a Midwestern college took a look at its need for a system of four new boilers in a 100-year-old facility, it was more than an issue of just getting more efficient steam production through the system.
“They needed to upgrade their boiler systems to meet EPA regulations, and the boiler replacement project was expected to meet their steam production needs for the next 20 years,” said Tony Smith, a senior mechanical engineer for Monsanto Enviro-Chem Systems, Inc., of St. Louis, which coordinated the design project for the new system. “We also had to maintain the architectural features of the brick powerhouse building. This was a historic building.”
There was one other crucial consideration. “The utilities couldn’t be turned off and couldn’t be disturbed, for any length of time,” said Mike Reim, piping designer with Monsanto Enviro-Chem. “There was university research that had been in place for 15 to 20 years. If we lost the utilities, that would all be for naught.”
Little wonder Smith said, “Due to the large scale of this project, the mass of existing piping and equipment, and the need to keep the facility operating undisturbed, it was a very complicated project both in terms of engineering and construction planning.”
One asset for the MECS, Inc., staff was the ability to work with 3-D models of the boiler system, giving them a clear view of how the existing pipe system would work with the new system. “3-D modeling is an enormously useful tool,” said Smith. “When we had the new boiler and the new piping models completed, we were able to design to within 1/16th of an inch.”
“We’d go to the field, take measurements, model those measurements, and put the new piping in. We didn’t have to rely on what our gut feelings were on the clearances.” Reim added.
The system also allowed designers to see the plant model in a CAD format so the entire design staff could see the existing boiler system piping. A laptop computer and design software allowed the field workers to input data on site and have that updated information available to everyone working on the project. Workers from the design team to the construction team saw real-time measurements and were able to make critical design decisions faster and more effectively.
The Monsanto team made the design data available to the project team. “We started with three engineers, and as the project progressed at any given time, we’d have from four to 12 people looking at the 3-D model,” Jim Cope, CAD system administrator said. “Now we have it deployed across the building on 50 to 75 desktops.”
The system also allowed for stress analysis to be done by computer, rather than by trial and error. “Once you cut into piping, the existing guides and supports act differently,” Reim said. “We had to plan very carefully not to overload the system. There was potential for huge damage.”
In the end, the 3-D CAD system made a tough project manageable because of its portability, flexibility and modeling capabilities. “When an issue would arise, we were easily able to go into the model and explore different solutions,” said Reim.
The industry view
Mapping software is a common tool in new construction, but it’s a big asset in retrofitting as well, said Dr. Jeffrey Hollings, senior vice president, Bentley Plant, Walnut Creek, CA. Bentley’s AutoPLANT Plant Design solution is one of the tools utilized in the 3-D CAD scanning community. “It’s very common, especially where downtime on existing systems needs to be minimized. This is where laser scanning can help.
“Upgrades, retrofits, and revamps are by far the most common capital projects being executed in North America these days. It has been highly publicized that not a single new refinery has been built since 1974,” Hollings noted.
Hollings said many factors should be considered when looking at a retrofitting project:
Feasibility of mapping – access to information, any restrictions on the mapping process, and the time needed to effectively map the facility
The availability of legacy documents, such as scans or existing CAD documents
An assessment of a company’s existing design base.
“Understanding what is currently in place will help the project engineers understand the tasks and tools required to execute the work,” Hollings said. But there’s also a big bonus at the end of that effort, as the Monsanto example illustrated. “The key advantage is that once mapped, the proposed changes can be planned off site, right down to construction simulation,” said Hollings. “This gives a great deal of confidence in the planned revamp process.”