W. Choueri, Veolia
Water Technologies & Solutions
efficient operation of crude oil distillation units (CDUs) improves profits and
distillate yield while optimizing production costs and reliability. Simultaneously,
it is possible to reduce caustic use, positively impacting downstream sodium
impact resulting in increased fluidized catalytic cracking (FCC) catalyst costs,
coker furnace fouling and other issues.
operations for maximum distillate yield involve controlling naphtha section
temperatures as low as practical without inducing amine salt formation and
corrosion. Amines contamination varies widely and comes from many sources from
within and from outside the refinery. Ideally, many elements should come
together to achieve a safely improved distillate yield (FIG. 1). The data,
learnings and controls possible from these elements must be utilized holistically.
overhead corrosion mitigation methods are typically labor-intensive,
unreliable, maintenance-heavy and time-consuming. They require many workforce
hours to gather data, perform calculations and control chemical feedrates.
Despite this investment, the intermittent data resulting from such methods miss
important chloride and amine variations, resulting in late or obsolete
decisions. Further, manual pH measurement and control can frequently accelerate
corrosion from overcompensating with chemical injection adjustments and missing
episodic periods of high corrosion.
manual ionic equilibrium salt point determination requires a significant number
of hours to obtain rapid results for a wide and dynamically changing basket of
amines, so shortcuts are often deployed that do not provide a complete picture
of salt-induced corrosion risk. As a result, either conservative approaches to
control salt deposition and corrosion are deployed to ensure safe operating
envelopes that negatively affect profitability, or a higher corrosion risk than
desirable is accepted to allow a wider operating envelope. Neither case is ideal
for promoting low risk and operating flexibility.
New lab and field technology. pH
measurement solutions incorporating transducers, rapid flow control, robust
filtering and coalescing make pH measurements for overhead systems reliable and
easier to maintain. Recent improvements in fluid handling have allowed accurate,
online, 24/7 pH measurement and control.
to this are new technologies to measure chlorides online. Recent data gathered
from field trials for chloride monitoring and control have shown a reduction of
the coefficient of variation from 44% to 14%, compared to manual lab samples. Several
solutions offer varying chloride reading frequencies ranging from 5 min–30 min.
recent advancements in amine speciation have made rapid and accurate onsite methods
economical and practical. The complexity of the operation and amine
quantification have become significantly easier while lowering costs and
reducing wait times. Fully understanding episodic salt point challenges through
rapid tramp amine speciation allows a greater ability to deal with corrosion
problems at the source.
treatment of CDU overheads for corrosion is the most common method of improving
reliability, other than desalting, water washing, temperature control and
advanced metallurgy. Manually controlled injection of chemicals is widespread
and longstanding in the industry. While neutralizers, filmers and caustic
treatment have proven effective, each has its potential for negative downstream
impacts, sometimes reducing overall potential. By using sensors and the automation
methods described above to control each of the individual chemical feeds in a
rapid, intelligent and synergistic way, corrosion mitigation can be improved while
maximizing distillate yield and minimizing the negative aspects of chemical
Online analytics and collaboration. The
data produced from the above solutions are often siloed and make it difficult
for operators to make the most effective decisions based on current conditions and
predictive analytics automatically perform daily saltpoint and dewpoint analysis
on the most recent data. Combining cloud-based calculations with comprehensive
and frequent amine speciation allows more rapid and targeted alterations to reliability
operating windows. Coupling this technology to automated pH and chloride
control via neutralizer and caustic injection allows the operator to optimize
the system by dynamically changing stable chloride setpoints.
centralized asset performance management, data is automatically transferred, stored
and accessed by all experts, operators and stakeholders. This allows a seamless
collaboration and one-click report generation. It also means all parties are
kept informed either through alarms, reports or direct customizable access.
automation to control neutralizer and caustic dosage based on pH and chloride
readings while linking decision-makers to data and learnings, the knowledge and
communication gaps are closed and significant improvements result.
Economic benefits. Unexpected
maintenance to an overhead system can result in millions of dollars in lost
opportunity for even one event.
one example, by using automation, online analytics and rapid amine speciation,
a refinery in North America conducted an 18°F temperature
improvement worth $5.9 MM/yr in improved distillate yield ($9,000/10°F
x 18°F/d x 365 d = $5.9 MM).
another example, several refineries have realized reduced maintenance hours for
sampling, analysis and control—down to a few hours per week for routine maintenance—and achieved > 99%
availability of the pH and chloride monitoring and control unit.
reduction of caustic use and sodium poisoning of FCCU catalyst by optimizing
chloride setpoints has been shown to result in > $350,000/yr in FCCU
catalyst savings alone. Each year, the reliability and maintenance costs of
corrosion are significant. The exact cost of global refinery corrosion is
unknown: various analysis reports by NACE International and others estimate
annual profit losses from refinery corrosion between $2 B and $12 B. Regardless
of the specific value, the impact of corrosion on refining has a significant
impact on refining economics.
the adoption of modern automation, control and analytics to help proactively
and systematically optimize the balance between production and reliability can
result in large returns on investment and simultaneous improvements to safety
and workforce requirements. HP
WILLIAM CHOUERI is a Global Product Manager for Veolia
Water Technologies & Solutions. He has more than 17 yr of experience in the water utilities, chemicals, and oil and
gas industries, with roles ranging from sales and growth leadership, to digital
and monitoring solutions, including the Suez Truesense and InSight APM
platform. He is now responsible for setting and executing the global strategy
for sensing and control in the oil and gas upstream, refining and chemical
processing markets. Choueri earned an MSC degree in water processes from Cranfield University (U.K.) in
2004, and an MBA from the University of Manchester (U.K.) in 2013.