Hydrocarbon Processing - January 2021 - 65

Process Controls,
Instrumentation
and Automation
A. CURETON, Emerson, Minneapolis, Minnesota

How to support condition monitoring
with wireless instrumentation networks
When WirelessHART first hit the
market in 2008, most of the native devices using it were process measurement
instruments. A pervasive sensing approach using these wireless instruments
is now being embraced as companies deploy wider Industrial Internet of Things
(IIoT) solutions as part of larger digital
transformation efforts. The following are
seven practical examples.
Pump monitoring. Pumps are critical to any process involving liquids, as is
evidenced by the number of installations
with two, or even three, redundant units
supporting a single application. Pumps
are maintenance intensive, suffering a
failure or some level of degraded operation once every 12 mos. on average.
Maintenance is typically reactive, costing
approximately 50% more than detecting
and resolving a problem prior to failure.
While strategic pumps frequently
have some existing monitoring equipment installed, there are many others
that should also be monitored. Before
the advent of wireless instruments and
networks, this monitoring was often too
expensive; however, pumps can now be
equipped with sensors to detect problems early so that appropriate actions can
be taken. Such wireless sensors include
those designed to monitor:
*	Vibration
*	 Bearing temperature
*	 Inlet/outlet pressure
*	 Strainer clogging
*	 Seal fluid pressure/level.
Devices using WirelessHART networks are available to perform all these
functions. The approach used to moni-

tor a given pump will depend on its size
and configuration, but the range of sensors illustrated is typical. It is important
to use a multi-measurement approach
because the various sensor technologies
tend to overlap, working together to help
diagnose problems.
For example, increased vibration
might be caused by shaft misalignment or
bearing deterioration. If the bearing temperature and noise have not increased,
then the technician doing the troubleshooting might verify alignment first,
since it is consistent with the symptoms.
Heat exchangers. Getting the most efficiency out of a common shell-and-tube

unit (FIG. 1) requires process measurements. The main operating parameters
are defined by:
*	 Inlet and outlet temperatures
for both the process and
transfer fluids
*	 Differential pressure (DP)
readings across the inlet and
outlet of the process fluid
*	 Flowrate for the transfer fluid.
The following is a typical setup using
WirelessHART instrumentation:
*	 Temperature transmitters
capable of sending data from
four sensors on one wireless
signal, reporting each reading
in turn. The host system

FIG. 1. A small group of strategic sensors can indicate both heat exchanger efficiency
and condition.
Hydrocarbon Processing | JANUARY 2021 65
Hydrocarbon Processing - January 2021

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