NVision Laser Scanning Streamlines Power Plant Conversions

NVision Inc. is using its laser equipment to assist coal-fired power plants in retrofitting turbines for more efficient dual-phase combined cycle gas turbine (CCGT) systems.

“A key part of transitioning this plant is refurbishing existing turbomachinery to accommodate the new combined cycle system,” says Steve Kersen, president of NVision. “NVision was brought in by plant management to laser-scan, then create models of the existing turbine housings in order to plan the installation/insertion paths of the new sensors and controls into the internal cavity of the housings.”

For the initial work, NVision employed its "Large Area" non-contact laser scanner to obtain complete scanning coverage of the internal and visible external surfaces of three turbine covers and “fixed” lower housings. The company then switched to a laser tracker for smaller turbine assembly details. Like the large area scanner, a laser tracker can measure over a large distance — but takes discrete points of areas where high accuracy and detail is the priority.

As it inspects objects, the scanner generates a point cloud consisting of millions of points, to comprise an exact duplicate of the object’s surface. Software integrated into the scanner converts the point cloud to an STL polygon, which serves as a template to create computer-aided design (CAD) models in IGES and STEP format, importable into any CAD software.

Measurement of other turbine components like inlet guides, airfoil contours and drive shafts used the company’s HandHeld portable 3D scanning device. 

NVison completed scanning in three days. The company then processed the data to a fully-aligned assembly in Siemens NX, providing plant engineers with a 3D model of the turbine assemblies. Engineers used this to analyze where they would install sensors and controls and, where necessary, redesign parts or structures for compatibility with the conversion.