Cover
Beyond the Control Room
COVER story
STORY
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As a follow-up to the “Second Layer of Automation” article in the March-April
2014 issue of Control Engineering Asia, Jonas Berge explains how information
from the wireless sensors are integrated with the rest of the enterprise to
support plant personnel beyond the control room.
I
n the article “Second Layer of Automation”
published in the March-April 2014 issue
of Control Engineering Asia, it was noted that
instrumentation to date has delivered better and
better process-critical measurements to safely control
the plant. It also discussed how plants are now being
modernized with a “second layer of automation”
for “pervasive sensing” to become “smart plants”.
By deploying large numbers of wireless sensors,
many of which are non-intrusive, to cover ‘missing
measurements’ in existing plants, these plants are
made more reliable, more energy efficient, more
environmentally friendly, and a safer place to work.
Some of these measurements collected through
pervasive sensing go to the operators in the control
room for increased situational awareness, but most
new information goes to personnel beyond the control
room to the offices of the disciplines responsible for
reliability and maintenance, energy efficiency, and
health, safety, and environmental (HS&E).
Plant historian integration
A wireless sensor network gateway is able to integrate
with multiple systems at the same time. Therefore,
wireless transmitters in the same network can send
their data both to the control system as well as to a
separate second system such as software applications
part of an Asset Management System (AMS) or to
a plant historian. AMS applications may integrate
using the HART-IP protocol while historians tend to
integrate using OPC. The control system may integrate
using Modbus/RTU over RS485 or Modbus/TCP
over Ethernet. In many companies, Modbus/RTU is
preferred for DCS integration to avoid cyber security
concerns with TCP/IP from the IT department.
The plant historian, also known as a Plant Information
Management System (PIMS), integrates with multiple
wireless sensor networks throughout all areas of the
plant as well as with the control system, safety system,
metering system, and package units, among others,
from many different vendors to collect data from all
these sources. Because the wireless gateway supports
OPC through a proxy, the sensor data can integrate to
just about any plant historian from any manufacturer,
Data in the historian reaches every player on team
for situational awareness.
The historian collects data from multiple sources do
extract information for multiple users.
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July-August 2014
Cover Story
The plant historian server stores all this plant
data in real-time, for up to millions of tags, over
decades. Over time, this adds up to huge amounts
of information, commonly referred to as “Big
Data”.
To make the Big Data more manageable, the
data can be organized by each asset such as a heat
exchanger or pump and structured hierarchically
according to the organization of the plant, making
it easy for personnel from different disciplines to
retrieve the right information later.
Analytics capabilities of the historian include
simple averaging, totalizing, equation based
calculations, advanced computations, alarms,
and Statistical Quality Control (SQC) to turn
raw data into actionable information and
notifications. Data from multiple sources such
as process variables from the control system and
Real-time analytics for equipment performance drives reliability and
measurements on process equipment by sensors
maintenance.
in the wireless network can be analyzed together,
new or old, since most, if not all, plant historians support OPC.
compared, and correlated. That is, measurements from multiple
Therefore it is possible to modernize any plant with pervasive
sensors can be aggregated to compute the condition of an
sensing.
asset, and the condition information of multiple assets can be
The plant historian is typically selected independent of the
aggregated to compute a Key Performance Indicator (KPI) for the
DCS because the historian is used enterprise-wide. The plant
plant. This analytical capability is ideal for equipment diagnostics
historian can cover multiple plants that multinational companies
for condition based maintenance. Notification via email and
have around the world, with each plant often having a different
instant messaging is also possible.
brand control system, of many generations. Global companies
Specialized third-party applications such as energy management
can, at an enterprise level, access data from every control system
software can access data from all the underlying data sources such
in all their plants around the world through the historian, adjusted
as the control system and wireless sensor networks through the
for time zone, in order to compare performance plants against
plant historian in real-time or as historical data. This integration
each other to identify best practices.
capability is ideal for energy management.
Many kinds of software for process applications support OPC
The plant information historian brings data beyond the control
and can therefore alternatively integrate directly with the wireless
room as the historian server is accessible from client computers
gateway through its OPC server.
on the corporate network enabling disciplines responsible for
maintenance, reliability, energy management, and
HS&E to access the data they need right from the
desk in their office. Access to the data is granted to
persons based on the requirements of their roles.
Any time data from new sensors have been made
available in the historian, it can be visualized on
the screen at anybody’s desk. Companies can build
a corporate centre of operations at which data
from any plant across time zones can be seen. This
enables benchmarking of maintenance, reliability,
energy efficiency, and HS&E performance across
plants around the globe, and a Subject Matter
Expert (SME) can access this information and
share their know-how with plants anywhere to
solve problems with pumps, heat exchangers, and
other assets.
Data from the DCS, wireless gateways, and other
data sources is available to the plant historian’s
report application which, using MS-Excel and a
web server, can publish role-based reports in the
form of a spreadsheet chart or pivot table, or as
dashboards including dial gauge graphics and
trends or as a scorecard. The data can also be
made available as web pages across the enterprise
through a web portal ideal for cross-discipline
The historian provides aggregated information as well as the ability do “drill
collaboration,
well beyond the control room.
down” into the raw data.
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CONTROL ENGINEERING ASIA | 11
COVER STORY
Reliability and maintenance
Reliability engineers and maintenance supervisors in most plants
do not have access to a majority of the information they need in
order to plan daily maintenance and to schedule turnarounds
of process equipment like pumps, heat exchangers, and nonprocess compressors because these assets are not instrumented
or connected to software. Some of the data is collected manually
in field rounds with a clipboard using portable vibration tester,
temperature gun, or manually taking readings from dial gauges,
level sight glasses, and variable area flowmeters onto log sheets.
Many points are simply not checked at all. The data is then keyed
into spreadsheets to calculate equipment performance. However,
these checks are typically too infrequent, time consuming, and are
error prone due to differential temperature points not sampled at
the same time, illegible data, and sheets lost.
Plants are now modernized with wireless transmitters for
vibration, temperature, and pressure mounted on process
equipment measuring these leading indicators of failure, feeding
their raw data into the plant historian. These measurements have
been missing until today. The real-time analytics component of
the historian is used to compute equipment condition from the raw
data from the sensors on the equipment and process variables from
the control system using specific software algorithms created for
each type of process equipment such as pumps, heat exchangers,
and compressors etc.
For instance, calculate heat-duty for each heat exchanger
bundle and trigger a notification when it gets too high. Other
equipment such as fans/blowers, air cooled exchangers, cooling
towers, agitators, and conveyors have other performance metrics.
This equipment-level diagnostics turns ‘dumb’ equipment into
‘smart equipment’. The information goes into daily, weekly, and
monthly maintenance and reliability reports on the computer
desktop and can even be seen in real-time.
Reliability engineers and maintenance supervisors thus get
their reports and the ability to check the current condition of any
piece of equipment around the plant from the historian client
software in their office or through the web portal at any time to
determine if cleaning, closer inspection, service, or other remedial
action is required on the equipment, and schedule maintenance
accordingly, thus ensuring equipment is kept in good condition.
Before a turnaround, the condition of all equipment can be
checked to determine which equipment needs overhaul and which
Real-time data collection and analytics drives energy
conservation measures.
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July-August 2014
ones do not, thus minimizing the duration of outage while at the
same time not overlooking equipment that really need service. It
may even be possible to postpone the turnaround until later. It is a
software-centric maintenance paradigm. The work processes have
to be written such that for each problem the analytics are able to
uncover, a recommended action is provided.
At the site level, the maintenance and reliability information
for equipment types in similar service can be compared between
different plant units to identify best practices. At an enterprise level,
reliability data can be compared between sites. SMEs at a corporate
centre of operations can remotely monitor assets at sites with
minimal staffing without local expertise, and are in better position
to provide advice as they themselves can access the data directly.
The historian does not take the place of machinery health
monitoring software part of the asset management system used by
vibration experts for vibration spectrum and waveform analysis.
Energy efficiency
Energy managers at most sites do not have access to the information
they need in order to drive reduction in energy waste because
consumption is not metered with unit-wise granularity, and is not
connected to software. These energy measurements are missing.
Whatever little data is available is put into spreadsheets manually.
Moreover, steam trap failures and leaking relief valves go
undetected because they are not instrumented or connected to
software. Some of the data is collected manually in field rounds
using portable acoustic testers and temperature guns. Many
of these are simply not checked at all. Checks are typically too
infrequent and as a result such invisible energy loss continues for
many months. A failed steam trap reduces heating efficiency and
could possibly result in damage to the equipment.
Wireless transmitters for metering of energy consumption of
all types like steam, compressed air, fuels, and water are now
deployed throughout the plant feeding their raw data into the
plant historian. Electricity consumption is also measured. A realtime energy management system analytics component integrated
with the historian is used to take the raw metering data from the
control system and wireless sensor network to roll-up the unit-wise
consumption into energy account centers. The information goes into
daily, weekly, and monthly energy reports on the energy manager’s
desktop. The target energy consumption is dynamically calculated
in real-time based on production and environmental conditions
using historical data or first principle algorithms. Performance
notification is sent when consumption exceeds the target.
Acoustic transmitters, which also measure the temperature, are
deployed on steam traps and relief valves. A summary of leaking
relief valves also goes into the daily, weekly, and monthly energy
reports generated by the historian and can even be seen in realtime. The real-time analytics component of the historian could be
used to compute relief valve losses.
The energy manager can identify where and how much energy
is being consumed across the plant and how much it is costing
the plant. The energy management system analytics component
identifies where and when consumption exceeds the target enabling
energy waste to be identified and reduced. Conversely, the energy
manager can also understand periods of best performance and
make actions repeatable. At the site-level, energy consumption
in similar plant units can be compared against each other to
identify best practice. At an enterprise-level, performance can be
compared between sites.
Cover Story
The historian energy analytics component provides real-time
energy consumption monitoring.
Leaking relief valves are identified such that overhaul on the
relief valve can be scheduled to stop waste of valuable product.
Steam trap failure reports can be forwarded to the third-party
service company in charge of steam trap replacement to make sure
the steam trap is replaced as soon as possible in order to stop waste
of steam, which is costly to produce. It is important to understand
that the cost of the steam trap monitoring shall not be compared
against the cost of the steam trap, but against the cost of wasted
steam. A steam trap can work for several years without problem,
but when it fails it could take up to a year before it is inspected the
next time, and the value of the steam wasted during this period can
be several thousands of dollars per year per failed steam trap. The
amount of money that can be saved by instead detecting the steam
trap failure at once far exceeds the cost of the solution.
The historian does not take the place of steam trap monitoring
software. The steam trap monitoring software is still required
to diagnose the steam trap based on the noise reading and
temperature from the acoustic transmitter. However, the steam
trap monitoring software can integrate with the historian using
OPC-A&E, allowing steam trap failures to be included in energy
reports. The real-time analytics component of the historian could
be used to compute steam trap losses.
Health, safety, and environmental
The operators at the DCS console need to be notified if a bypass
valve or dyke valve is left open after proof testing so they can send
somebody to close it; or if a safety shower or eye wash is activated
so they can send people to assist the person in distress; or when a
relief valve releases so they can correct the process problem. At the
same time, the HS&E officer also needs to know if a bypass valve
Real-time data collection drives HS&E risk reduction and
compliance.
or dyke valve is left open after proof testing, or if a safety shower
or eye wash is activated so the incident is recorded. When a relief
valve has releases this is only discovered next time the relief valve
is inspected which could be days later. When the release actually
started, and how long it lasted is not know so the release quantity
cannot be estimated correctly. Hydrocarbon leaks around tanks or
onto floating roofs may go undetected and are a fire hazard. Lastly,
many plants rely on field operator rounds with clipboards to read
several dial gauges, sight glasses, VA meters, and gauge level by
dip stick, or grab product samples.
Sites are now modernized with wireless transmitters for these
missing measurements passing their raw data to the control system
and to the plant historian. The information in the control system is
used by the operators. The information in the historian is used for
daily, weekly, and monthly reports for the HS&E officer.
Pervasive sensing in combination with a plant historian helps the
HS&E officer meet regulatory emission reporting requirements
and provides the ability to easily verify that bypass valves and
other valves are not left in the wrong position. It also automates
the documentation of periodic function check of safety showers
and eye wash stations.
Reducing field operator rounds with clipboards to read dial
gauges, sight glasses, VA meters, gauge level using dip stick, or grab
sample has two positive impacts: personnel spend less time exposed
in the field, and they are freed up to do more value added tasks. At
an enterprise-level, HS&E incidents and compliance at one site
can be compared to that of other sites.
Integrated operations
The Integrated Operations concept is primarily used on oil and
gas production, but parts of this concept also apply to downstream
and other process industries. A remote link between corporate
operations and engineer centre and sites around the world enable
Subject Matter Experts (SME) to remotely view any asset to
assist in diagnostics and troubleshooting etc. That is, an SME in
a central location can support many plants which do not have
an SME at site. This is enabled by secure broadband Internet
connection for plant data and for video conferencing.
Many plants are now installing WirelessHART gateways
throughout their plant units to enable deployment of pervasive
sensing strategies. Wireless sensor data is being integrated both
into the existing control system and the plant historian. The
historian modules for asset monitoring and energy management
are also required. Alternatively, a new Asset Management System
with an asset monitoring software can be used.
Plant modernization does not require system migration. The
wireless gateway integrates with existing systems using TCP/IP or
serial communication. It should be noted that the sensors themselves
need not have an IP address for their data to be accessible from
anywhere in the world, they just need digital communication and a
unique identifier which is the basis for the Internet of Things (IoT). In
the future, this non-process-critical data could be stored on a server in
the “cloud”, accessible from anywhere by those authorized. Because
the sensors required to cover the broad spectrum of applications for
maintenance, reliability, energy efficiency, and HS&E are all available
with WirelessHART communication, only a single type of wireless
gateway is required throughout the plant. Once such a wireless
infrastructure has been deployed the data can be shared by all plant
disciplines.
CEA
Jonas Berge is Director of Applied Technology at Emerson Process
Management.
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