12
Chapter
In most cases, prevention is less costly
than a cure, and the best prevention is
continuous monitoring of the materials.
The cost of an automated temperature
monitoring system using IR cameras is
a modest and worthwhile investment.
System design can take the same form as
the one described earlier for hazardous
waste barrels. Cameras are congured
to generate a direct alarm output to an
operator when user-dened maximum
temperature thresholds are exceeded.
Audible and visual alarms in a control
room draw the operator’s attention to a
possible spontaneous re development.
Various types of software have been
developed to isolate trouble spots, such
as the waste pile zone monitoring system
depicted in Figure 7.
Although self-ignition usually starts
within the bottom layers of a stock pile,
continuous monitoring of the surface
reveals hot spots at an early stage (Figure
8), so measures can be taken to prevent
a major re from breaking out. Large
storage yards generally require multiple
cameras for total coverage, with the
cameras mounted on metal masts above
the stock piles. This calls for cameras with
housings and other features designed
for reliable operation in harsh industrial
environments.
Critical Vessel Monitoring (CVM). There
are several applications where the
temperature of a vessel and its contents
are critical. The vessels could be used
for chemical reactions, liquid heating,
or merely storage. For large vessels,
the use of contact temperature sensors
poses problems. One reason could be
non-uniform temperatures throughout a
vessel and across its surface. This would
require a large number of contact type
sensors, whose installations can become
quite costly.
For most CVM applications, a few IR
cameras can image nearly 100% of a
vessels surface (Figure 9). Moreover, they
can measure the surface temperature of
the CVM to trend and predict when the
internal refractory will break down and
compromise the mechanical integrity of
the system. If specic regions of interest
(ROIs) must be focused on, IR camera
rmware (or external PC software) allows
the selection of spot temperature points
or areas for measurement.
Again, some variation of the systems
described earlier can be used. Depending
Figure 7. Control room for waste pile processing, and screen capture of the zone monitoring layout,
which uses a FLIR IR camera on a pan-tilt mount for re hazard warning.
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