POWER December 2012 - 86

PLANT DESIGN
Figure 2 shows a LIDAR unit mounted on a standard surveyor's
tripod. The unit has two windows-one on the side and one on the
top-through which it sends and receives the laser beam. LIDAR has
an integral camera to take digital photos that are used to assign color
to points from the scans. The handle can be removed to allow the
scanner to scan directly above if the area above the scanner is included
in the volume of interest.
Data describing the space near the mills was obtained with a LIDAR
scanner in two days by technicians working safely away from operating
equipment. Each scan takes 5 to 15 minutes, depending on the
resolution and whether photos are taken. For this project, 25 scans were
obtained for the six limestone mills.
2. Process the Scan Data. Back in office, the registered point
cloud file is created and the file is colorized.
In the limestone mill project, once the scans were registered into a
single point cloud, designers could measure existing conditions and
check for interferences entirely in computer-assisted design (CAD)
software, eliminating the need for several trips to the plant to record
myriad field measurements. The point cloud captured encumbrances
that were not recorded on as-built drawings and which interfered with
the layout of the new platforms.
Figure 3 shows the raw, uncolorized scan of the limestone mill,
and Figure 4 shows the same scan after photos from the scanner were
used to assign colors to the points. The color makes it easier-in some
cases much easier-for the designer to discern objects in the scan.
3. Import and Post-Process Data. Next, the point cloud file is
imported into a 3D CAD file using third-party software. Then postprocessing
of the registered point cloud file takes place so that extraneous
points are eliminated. The range of the scanner can be limited
in the field, but limiting the range does not speed up the scan, so the
scanner is usually left to scan everything.
The point cloud can also be divided into " levels " or specific areas
of interest. This reduces the point cloud file size.
Finally, undesirable elements, such as scaffolding, vehicles, and
people are removed.
4. Model Existing Equipment, Structures, Pipes, and Conduits.
As the designer goes through the point cloud to lay out a new
structural model, he or she can cut slices through the point cloud and
eliminate some of the clutter. The designer can see the structural elements,
railings, and equipment. As the designer zooms in with the
point cloud file, objects become much clearer.
4. Colorized cloud data. The point cloud shown in Figure 3 now
includes color information provided by the integrated digital camera.
Courtesy: JQ
In addition to large pieces of equipment, the point cloud is used to
model elements such as pipes, ducts, and conduits, including hangers,
valves, concrete pedestals, and structural steel members. Even the
flange width, beam depth, and flange thickness of existing structural
members can be measured from the point cloud.
5. Lay Out and Design the New Structure(s). Once the 3D
model of the as-built configuration is completed, the same 3D
CAD file can be used to design the new elements, with particular
attention paid to existing elements to avoid interferences. Most of
the new structure is modeled with the point cloud turned off, but
the designer occasionally toggles the point cloud back on to make
sure the structure doesn't clash with existing piping, structures,
or equipment.
Figure 5 shows the 3D model of the new platforms and the point
cloud of the existing plant. In general, every valve, instrument sensor
or gauge, small-diameter tubing, and flexible electrical cabling
is not modeled, but these items are accounted for when the structure
is laid out around the items in the point cloud. Figure 6 shows cable
trays and pipes that the new platforms were designed around. Figure
7 is a detailed view of the platforms' 3D model, including a swinging
hatch that affected the location of railing.
5. Perfect fit. The 3D model of the new platforms is superimposed
on existing equipment, structure, pipes, and electrical conduit produced
from the colorized point cloud. Courtesy: JQ
6. Infinite views. The 3D model can be manipulated in any direction
and at any zoom during design. Shown are the new platforms built
around the model of the existing plant equipment generated from the
point cloud. Courtesy: JQ
December 2012 | POWER
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POWER December 2012

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