battling corrosion in refineries with in-line process ... · pdf filebattling corrosion in...
TRANSCRIPT
News5
Battling Corrosion in Refinerieswith In-Line Process AnalyticsIt is estimated that the global costs of refinery corrosion are in the order
of 15 billion USD annually. Even though the problem may never be fully
solved, advances in process analytics with a new generation of intelligent
pH sensors offers huge cost savings.
Complex problemThe main difficulty in combating refinery
corrosion is that the problem has not one
single source, but many. In addition, some
of the corrodents involved might interact
and increase or inhibit each other’s cor-
rosivity. Physical process conditions also
play a role; so temperature, flow, etc. have
to be taken into account, as does the refin-
ery infrastructure itself. Given the number
of variables then, it becomes clear that
corrosion is a complex issue.
SulfurBecause it provides a lower feedstock cost,
sour crude is preferred by refineries. In
sour crude sulfur is present in the form of
mercaptans, H2S, sulfide salts, elemental
sulfur and so on. Many of these species are
reactive and cause sulfide stress cracking
and sulfuric acid corrosion throughout
the refining process.
AcidityBesides sulfur, crude contains many spe-
cies that are quantified by the total acid
number (TAN) of the oil. Typically found
are naphthenic acids, which are organic,
but also mineral acids (H2S, HCN, CO2,
etc.) can be present, all of which can
contribute significantly to equipment
corrosion. Even materials suitable for sour
service do not escape damage under such
an onslaught of aggressive compounds.
Again, because of cost considerations, a
trend towards a preference for crudes with
a higher TAN is noticeable.
Petrochemical Perspectives in Liquid Process Analytics
INGOLD Leading Process Analytics
Automated cleaning and calibration system EasyClean 400
2 METTLER TOLEDO Petrochemicals News 5
Publisher / Production Mettler-Toledo AG
Process Analytics
Im Hackacker 15
CH-8902 Urdorf
Switzerland
IllustrationsMettler-Toledo AG
Viorel_dudau, Harper3d, Reflekcija,
Imdan | Dreamstime.com
Subject to technical changes.
© Mettler-Toledo AG 12/09
Printed in Switzerland.
DesaltingDesalting of the crude is the first step in
refining that has a direct effect on corro-
sion and fouling. By mixing and washing
the crude with water, salts and solids
transfer to the water phase which settles
out in a tank. An electrostatic field is in-
duced to speed up the separation of oil and
water. In this way, inorganic salts that
could cause fouling or hydrolyze and form
corrosive acids, are largely removed. Often,
chemicals are added in the form of demul-
sifiers to break the oil / water emulsion.
Other chemicals such as caustic soda are
also introduced to neutralize acidic com-
ponents. Uncontrolled feeding of caustic
can, however, have a detrimental effect
and result in a significant quantity of
contaminants ending up in downstream
processes, which may have serious conse-
quences.
DistillingEven with an efficient desalting operation,
an abundance of corrodents can still ap-
pear during downstream processing. A
good example of this is the sour water
corrosion that occurs in the crude distiller.
During the process lots of acid gases are
formed of which hydrogen sulfide is noto-
rious. Steam, which is injected into the
crude tower to improve fractionation,
condenses in the upper part of the unit.
The hydrogen sulfide dissolves in the
condensate and forms a weak acid which
is known to cause stress corrosion crack-
ing in the top section of the tower and in
the overhead condenser. This may lead to
frequent retubing of the condenser and in
severe cases to replacement of the entire
crude tower top.
In-line analysisAll the problems mentioned above, and the
costs associated with them, can be signifi-
cantly reduced by reacting to the
measurements obtained from accurate
in-line analysis of pH values.
In respect of desalting, constant in-line
monitoring of pH in the desalter water ef-
fluent allows for efficient dosing of caustic
or acid which can result in significant
cost savings. The stability of the oil /
water emulsion depends partly on pH.
Maintaining the pH of the mixture within
a certain range helps the demulsifier
chemicals in breaking the emulsion by
interacting directly with the water droplets.
The speed and quality of the separation
process can thus be improved which leads
to less water carry-over, which in turn can
result in a significant reduction in down-
stream corrosion and fouling.
Even though corrosion in the disitiller is
well known to refinery operators, effective
counter measures are not always in place.
Typically, corrosion inhibitors and lots of
neutralizers such as caustic soda or am-
monia are injected with the aim of
increasing the pH of the sour water.
Although this is an obvious response to the
problem, the cure can be worse than the
disease. The presence of various acid
gases and ammonia can result in solid
salts depositing including ammonium
bisulfide, one of the main causes of alka-
line sour water corrosion. pH levels higher
Transmitter M700
METTLER TOLEDO Petrochemicals News 5 3
Automated cleaning and calibra-tionDespite innovative design, even the best pH
electrode needs frequent maintenance. Of
any process instrument, the pH electrode
probably has the widest rangeability and
an extraordinary sensitivity that covers it.
Depending on the process application,
after a certain time in operation a calibra-
tion is required to make sure the instrument
will maintain its reliability and accuracy.
When very sour crudes are refined, or
when the overhead hydrocarbon / water
separation is not optimal, sensor mainte-
nance may be required to an extent where
it becomes problematic and the value of
the measurement is no longer considered
an asset. In such applications the imple-
mentation of an automated cleaning and
calibration system is the answer.
Proven to be of great value in numerous
“dirty” applications is METTLER
TOLEDO’s EasyClean 400 system. Fully
certified for use in hazardous areas, this
unit enables the most difficult pH mea-
surement tasks. When necessary,
EasyClean 400 pneumatically retracts
the electrode and gives it a thorough
cleaning followed by a two-point calibra-
tion, without any human intervention.
The standalone unit carries cleaning and
buffer solutions on board and requires no
more than instrument air and water sup-
plies to carry out its tasks. An extra valve
is available in case an additional cleaning
liquid is needed.
than 7.6 dramatically increase ammonium
bisulfide corrosion and by overdosing
caustic that level is easily achieved. Proper
neutralizer dosing through pH measure-
ment of the overhead condenser boot water
will not only reduce corrosion but also
reduce chemical consumption.
Most pH electrodes are not specifically
designed for refinery applications and
hence suffer from poor performance in the
presence of high sulfide levels and the
substantial hydrocarbon load. METTLER
TOLEDO’s understanding of the conditions
in petroleum refineries has led to the de-
velopment of pH electrodes specifically
designed to cope with high temperatures,
extremes of pH value and solid contami-
nants.
Xerolyt ExtraThe most common cause of sensor failure
in refineries is poisoning and fouling of
the reference electrode system. This results
in drift of the pH measurement. Oily sub-
stances and solids may coat or clog the
diaphragm of the reference junction which
obviously has a negative impact on sensor
performance as well.
METTLER TOLEDO’s InPro 4260 i pH
electrode features Xerolyt Extra solid
polymer electrolyte. The InPro 4260 i has
an open junction, which is in fact a hole
that brings the solid electrolyte in to direct
contact with the process medium. Contrary
to the miniscule capillaries of any other
type of diaphragm in conventional pH
electrodes, the diameter of the open junc-
tion is extremely large and much less
susceptible to clogging or fouling. Another
significant difference is in the choice of
polymer electrolyte. Xerolyt Extra has
been designed specifically for service in
hydrocarbon environments and provides a
strong and lasting barrier against sulfide
poisoning.
www.mt.com/pro-pH
Intelligent Sensor ManagementIn the end, all pH electrodes will show
signs of aging and performance will start
to fall below the reliability required.
METTLER TOLEDO pH electrodes with
Intelligent Sensor Management (ISM)
communicate their remaining operating
life through a digital signal that also
carries measurement values, temperature
and enhanced sensor diagnostics. Based
on actual process conditions and history,
the Dynamic Lifetime Indicator will pre-
dict when sensor replacement is due. This
is one of many interesting features of the
ISM platform that truly enables predictive
maintenance.
Lower costs and more uptimeAdvances in sensor technology and intel-
ligent automation of the measurement
system enable pH measurement in the
most challenging refinery sour water en-
vironments. When the correct equipment
is chosen, in-line pH measurement and
management facilities have proven to be
of great value in reducing plant-wide cor-
rosion and the consumption of chemicals
such as pH control reagents and corrosion
inhibitors. This not only results in signifi-
cant cost savings but also in increased
earnings through longer process uptime.
If you want to reduce the cost of corrosion
at your facility, go to:
www.mt.com/ISMpH electrode InPro 4260 i
4 METTLER TOLEDO Petrochemicals News 5
Self-
clea
ning
pH
Sys
tem
Overcoming technical problemsHowever, there was concern that the solids
concentration in the primary clarifier was
substantially higher than in the secondary
clarifier, and whether increased mainte-
nance demands would offset any potential
benefit in chemical savings. The local
METTLER TOLEDO sales representative
acknowledged that the conditions in the
primary clarifier were likely too extreme
for unassisted pH operation, therefore re-
quiring some type of automated cleaning
system.
The selected measuring systemSince the sensor is mounted directly in the
open basin, the proposed system included
an EasyClean 100. The sprayhead
mounted on the end of an InDip housing
directs bursts of air at the head of the
electrode at programmed intervals. The
strong turbulence generated by the air jets
prevents solids and films from accumulat-
ing at the electrode surface. The timing
interval is controlled using the rinse relay
contact of the pH 2100 e 4-wire transmit-
ter, and has been set for operation every
eight hours. Completing the system, the
InPro 3250 pH electrode was selected for
its internal pressurized reference electro-
lyte, further helping to keep the reference
junction clean.
Dramatic Reductionin Maintenance and Chemical CostsThe expense of regular maintenance plus chemicals for wastewater pH
control was troubling a large US refinery. They asked METTLER TOLEDO
for a cost saving solution. The installed system has reduced both
expenses substantially.
Major US refinerOur customer is a leading international
integrated energy company and is one of
the largest refiners in the United States.
One of their refineries processes over
200,000 barrels of oil per day producing
gasoline, fuel oils and a variety of petro-
chemicals.
Challenging wastewater treatmentMany refinery operations consume large
amounts of water, resulting in millions of
gallons per day of wastewater requiring
treatment. Accepting waste from unit op-
erations throughout the refinery presents
a challenge for pH measurement as the
water contains oils, residual sulfide and
ammonia compounds, and the pH level of
effluent from different locations can be
radically different.
New pH measuring concept requestedA competitor’s pH electrode was being used
in an existing application in a secondary
clarifier following biological treatment.
Solids and film build-up on the sensor
required weekly manual cleaning. The
treatment plant operator indicated that
the ideal location for pH control would be
in the upstream primary clarifier.
Catching pH excursions earlier in the
process would provide more stable read-
ings downstream and minimize chemical
costs resulting from overdosing of lime
used for pH control.
Selecting the right sys-tem can greatly reduce your maintenance re-quirement
METTLER TOLEDO realizes that you want to keep maintenance time to a minimum while ensur-ing your pH measurement point is always operating optimally. We offer a range of pH elec-trodes, transmitters, housings and cleaning systems for use in the Petrochemical industry. Our sales representatives will en-sure you have the right systems for your processes.
Discover more at:
Best Practice
www.mt.com/pro-pH
Transmitter pH 2100 e
METTLER TOLEDO Petrochemicals News 5 5
InPro 3250 pH electrode The InPro 3250 family is a pre-pressurized,
liquid-filled, low-maintenance pH and
temperature sensor for in-line measure-
ments in demanding applications. Its
durable design is well suited for harsh
chemical process conditions. These rug-
ged electrodes lead the industry for fast
and precise measurements. They are
available with an expanded selection of
different pH-sensitive glass membranes.
BenefitsOperational results have more than met
expectations. Electrode maintenance has
been dramatically reduced from once ev-
ery week to less than once per month, even
though the system is now located in a
much dirtier installation. The accuracy of
the real-time pH measurement has also
led to substantial savings on chemical
costs.
EasyClean cleaning systemThe EasyClean 100 system is designed to
provide completely automatic sensor rins-
ing. It can be used with a stationary
InDip housing with a sprayhead for open
tank and basin applications. The
EasyClean 150 can use either water rins-
ing or compressed air to create turbulence
to prevent stubborn build-up.
pH electrode InPro 3250
www.mt.com/pro-pHwww.mt.com/EasyClean
pH 2100 e transmitterThe pH 2100 e transmitter is a proven high
performance transmitter that can be used
in the simplest or most demanding of
applications. Available in either 4-wire or
2-wire versions, this enhanced pH trans-
mitter line offers superior performance,
advanced sensor and transmitter diagnos-
tics and leading edge functionality.
To reduce maintenance and chemical
costs in your refinery, go to:
Schema of a typical automated loop
Sprayhead for InDip housing ensures a proper cleaning
Power in Power in
Transmitter EasyClean 100
6 METTLER TOLEDO Petrochemicals News 5
O 2 G
as M
easu
rem
ent
This technology, with a proven industrial
track record due to its simplicity and rug-
gedness, is ideally suited for the in-situ
measurement of gaseous oxygen.
METTLER TOLEDO offers a comprehen-
sive range of amperometric systems with
sensors for wide application coverage, re-
tractable housings for sensor extraction
without process interruption, and trans-
mitters for signal conversion and
connection to process control systems
using HART®, FOUNDATION fieldbus™
or PROFIBUS®. Naturally, the complete
measurement system is available with
ATEX Zone 0 / FM Class 1 Div 1 approval if
required.
Amperometric sensors can be maintained
in two minutes, with minimum impact
on your running process. All that is re-
quired is to replace the membrane body
and fill it with fresh electrolyte solution.
Subsequent calibration can be performed
on site using air as a calibration gas.
Measure Oxygen Where it Really MattersDirectly in Your ProcessPerformance of gaseous oxygen measurement is now redefined with
METTLER TOLEDO’s amperometric systems. They not only allow reliable
and stable measurement, they are inexpensive to maintain and, what’s
more, do not require any gas sampling system.
Unwanted oxygenOxygen levels in industrial processes are
heavily controlled to contain the risk of
explosion of flammable liquids and dusts,
as well as to protect products against oxi-
dation. Not only is oxygen monitoring a
critical issue in transport systems, storage
tanks or centrifuges, it can also nega-
tively affect the yield of a chemical
reaction in a vessel.
Many solutions – which is best?When selecting a vendor for a measure-
ment system, technologies and solutions
abound, but in many cases a trade-off
exists between sufficient performance and
reliability, and reasonable maintenance
effort and system availability. In order to
function correctly, paramagnetic systems
need to protect the measurement cell from
heat, moisture and / or corrosive gases.
However, the more instruments there are
between the process and the sensor, the
longer the response time will be and the
higher the probability of system failure.
Amperometric: simple and reliableLooking at the field of dissolved oxygen
measurement however, membrane-based
amperometric sensors using the Clark
principle offer an alternative. For decades
they have demonstrated optimum perfor-
mance in a wide range of applications
ranging from fermentation processes in
breweries, in biopharmaceutical indus-
tries or in chemical process applications.
www.mt.com/o2-gas
Intelligent sensors for smart processesAll amperometric sensors from METTLER
TOLEDO are available in digital versions
equipped with Intelligent Sensor
Management (ISM) technology. With the
Plug and Measure feature, pre-calibrated
sensors can be immediately used in the
process, minimizing the time necessary
for maintenance and without the need for
specialist know-how. Additionally, ISM
sensors have built-in self-diagnostic
abilities in order to detect early signs of
failure such as low electrolyte levels, and
alert users before measurement quality or
process availability is impacted.
If you want to save costs on O2 measure-
ment at your facility, go to:
www.mt.com/ISM
F O2
Paramagnetic system
N2 in
METTLER TOLEDO solution
The sample path through a The METTLER TOLEDO solution paramagentic system is long and slow. measures directly in the vessel – immediately.
METTLER TOLEDO Petrochemicals News 5 7
Cabl
eles
s So
lutio
n
tion. It is also the perfect answer for
remote monitoring tasks.
The W100 supports ISM sensors for pH, DO
as well as 4-E conductivity, which are
compatible with the advanced transmitter
line M400 or the value transmitter line
M300.
Additional benefits of the cableless solu-
tion include the long battery lifetime of up
to 6 months, and the communication
range of up to 150 meters.
Discover more at:
Tricky Sensor Installation Point?Go Cableless!Proper wiring between sensor and transmitter can be very costly, especially
in locations with limited access or where moving parts can be a hazard.
The cableless solution W100 gives you the option to solve expensive and
challenging installation conditions at a very reasonable cost.
No more cablesWith the W100, METTLER TOLEDO offers
an innovative solution for cost-intensive
measurement point installations. Based
on reliable and industry-proven wireless
technology (according to IEEE802.15.4),
the W100 replaces the cable between
METTLER TOLEDO Intelligent Sensor
Management (ISM) sensors and the
transmitter, and provides bi-directional
digital data transfer with full calibration
and diagnostics functionality.
Real-time monitoring of the measurement
value as well as auto-recognition of the
sensor is ensured. Additionally, the W100
convinces with its very simple one button
operation, which is also the basis for the
easy pairing between transmitter and
sensor. Thanks to the LED display, the
state of the W100 can be recognized at a
glance. Installation at existing ISM mea-
suring points is simple as there is no need
to change any transmitter settings.
For many applicationsSince there is no cable to be laid, the sys-
tem offers great advantages in applications
where high installation costs due to
physical barriers or contamination risks,
exist. Also, in applications where the
measuring point is needed only temporar-
ily, where the installation of the sensor
has to be changed several times, or where
the sensor is mounted on a moving part,
the W100 is a highly cost-efficient solu-
Stay one step ahead of maintenance with ISM
A METTLER TOLEDO ISM mea-suring system with the W100 will not just save on installation costs; ISM also reduces the maintenance and calibration effort to a mimimum. This con-siderably improves process reliability, productivity and sys-tem availability.
Find out how ISM can help you, at:
Best Practice
www.mt.com/ISM
www.mt.com/W100
8 METTLER TOLEDO Petrochemicals News 5
Com
preh
ensi
ve W
ebsi
te The Information you Want is at www.mt.com/pro
The METTLER TOLEDO Process Analytics web-site contains a vast amount of up-to-date information on all our products and services.
Content is localized for your country and tailored to suit your selections.
Simple layout allows you to quickly find the infor-mation and features you are looking for.
n Learn about our most recent product develop- ments
n Register for free webinars
n Request further information on products and services
n Obtain a quote quickly and easily
n Download our latest white papers
n Read case studies relevant to your industry
n Access buffer and electrolyte solution certificates
n and more...
A typical Product page: with Features
and Benefits and quick access to rele-
vant application information,
related products and downloads
METTLER TOLEDO Petrochemicals News 5 9
The Information you Want is at www.mt.com/pro
Search by Product or by Application n Read the latest product news
n Access our Newsletter archive
n Find out when our next Trade
Show or Exhibition is in your
area
n Register for free webinars
presented by our industry
experts
n Download our White PapersApplication pages help guide you to the
products that are right for your processes
10 METTLER TOLEDO Petrochemicals News 5
Plug and Measure
Inte
lligen
t Sen
sor M
anag
emen
t Intelligent Sensor Management Reduces Life Cycle Costs and Improves Process Safety
Intelligent Sensor Management (ISM)ISM reduces the installation, maintenance and calibration effort for METTLER TOLEDO’s digital sensors to a minimum. This considerably im-proves process reliability, productivity and system availability.
Reliable installationDigital communication between sensor and transmitter means signal is always reliable and unaffected by moisture.
Intelligence – starts in the headISM sensors are equipped with integrated elec-tronics in the sensor head that store all relevant sensor parameters and includes algorithms for enhanced sensor diagnostics.
Predictive maintenanceIntelligent diagnostics information is calculated and displayed on the sensor’s transmitter and tells you if the sensor needs maintenance or replacement – no more downtimes due to sen-sor failure!
System integrationKey ISM parameters can be fully integrated in a process control system via PROFIBUS® PA or FOUNDATION Fieldbus™.
■ Sensors are immediately recognized when connected to the transmitter – eliminating difficult configuration procedures.
■ Operational availability of measurement point within seconds.
■ Wireless module available for transmission from sen-sor to transmitter – no need for costly cable installation.
■ Sensors can be pre-calibrated in the lab and stored for later use, saving time and increasing operational avail-ability.
METTLER TOLEDO’s ISM product range includes…
… a wide range of sensors for … advanced single- and multi-channel transmitters … software applications ■ pH ■ 4-wire ■ iSense Asset Suite ■ dissolved and gaseous O2 ■ 2-wire ■ pH data logger ■ conductivity ■ wireless module ■ turbidity
METTLER TOLEDO Petrochemicals News 5 11
Intelligent Sensor Management Reduces Life Cycle Costs and Improves Process Safety
Diagnostics Maximum Performance
■ Any sensor maintenance requirement is recognized at an early stage, reducing downtimes and minimizing plant operation costs.
■ Dynamic Lifetime Indicator estimates in real time the remaining lifetime of the sensor.
■ CIP / SIP cycles counted automatically.
■ Sensor spider diagram for fast troubleshooting.
■ iSense Asset Suite software offers you a unique means of optimizing the performance of ISM sensors for en-hanced reliability and process safety.
■ Key Performance Table enables you to evaluate the condition of an ISM sensor at a glance, without the need of a transmitter.
■ Documentation of every calibration as well as the entire sensor history – documentation requirements to regu-latory standards are easily met.
METTLER TOLEDO’s ISM product range includes…
… a wide range of sensors for … advanced single- and multi-channel transmitters … software applications ■ pH ■ 4-wire ■ iSense Asset Suite ■ dissolved and gaseous O2 ■ 2-wire ■ pH data logger ■ conductivity ■ wireless module ■ turbidity
Intelligence starts in the head
www.mt.com / ISM
Visit for more informationwww.mt.com/pro
Trouble-free Conductivity Measurementa Completely New SolutionReduce your operating costs right from measurement point in-stallation down to configuration and maintenance. This is all possible with the advanced M400 transmitter line from METTLER TOLEDO. It offers conductivity measurement based on ISM sen-sors as a new feature thus providing the benefits of ISM technology for petrochemical applications. Conductivity sen-sors with Intelligent Sensor Management (ISM) technology carry their own calibration data for easy commissioning. They can monitor themselves and provide real-time information for up-to-date sensor diagnostics. With ISM, installation costs are significantly reduced.
www.mt.com/ISM
Get in-line with METTLER TOLEDO
Mettler-Toledo Ingold, Inc. 36 Middlesex TurnpikeBedford, MA 01730, USATel +1 781 301 8800Fax +1 781 271 0681Toll Free: 1 800 352 8763Email: [email protected]