REFINING GAS PROCESSING PETROCHEMICALS ptq Q3 2024 REFINING GAS PROCESSING PETROCHEMICALS Q4 2026
STEAM CRACKER FOULING MOTOR RESTART PROTECTION
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Q4 (Oct, Nov, Dec) 2026 www.digitalrefining.com ptq
3 Predicting profitability in 2027 Rene Gonzalez
5 ptq&a
11 Mitigation of ammonium chloride salt formation in FCC main fractionator Adilson Cavalheiro Borges Gutierres FCCSA Carlos Alberto Rivera Corredor and Manuel Julian Ardila Pimiento Ecopetrol Eric Rutan and Cliff Avery Ketjen Corporation
16 When an alternative constraint steals the spotlight Jeff Maday KBC (A Yokogawa Company)
23 Overcoming refractory nitrogen challenges in ULSD hydrotreating Xavier E. Ruiz Maldonado Topsoe North America
35 Recovering steam cracker efficiency Scott Donson IGS TubeTech
43 Enhancing amine unit reliability in undergoing refinery transformation Lorenzo Spagnuolo Dow 49 Integrating refining with chemicals, petrochemicals, and fertilisers Sabrin Khan and Chiranjib Haldar Genesis, Technip Energies India Limited 57 AI/ML-driven process upset analytics: C3 splitter case NC Chakrabarti, Akalesh Tiwari, Manish Biswal, Sougat Das, Balamurugan Mohan, and Jesse Mallhi Reliance Industries Limited
67 From inerts to efficiency: Hybrid SRU designs Debopam Chaudhuri, Ayan Dasgupta, and Akanksha Pandey Fluor 75 Selection method for motor restart in petrochemical plants Wang Xin and Li WenPing CTCI Beijing
81 Monetising biomass-to-SAF investments Kristine Klavers EcoEngineers 85 Identifying patterns in recent refinery incidents Manya Novari Kagera Technologies
89 The real work begins after the alarm Dinesh Varadharajan Kissflow
Cover The Jamnagar Manufacturing Division (JMD), owned and operated by Reliance Industries Limited, houses two co-located refineries with a combined processing capacity of 1.4 million barrels per day. Courtesy: RIL
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Predicting profitability in 2027
T he petroleum refining business is doing well with high diesel margins and near-100% utilisation rates. US refiners are experiencing unprecedented profit margins, driven by high prices for gasoline and diesel amid supply dis - ruptions. Elsewhere, European refining capacity is unusually tight due to closures, low stocks, and reduced access to Russian output. Meanwhile, Brazil’s Petrobras, reported refinery utilisation reaching 101% for the quarter due to optimised pro - cessing and reliability initiatives. Record profits and high margins provide insights into the overall economic health of refining operations, reflecting demand and capacity. In the US, 3-2-1 crack spreads reflect higher throughput and lower operating costs. For example, Valero Energy’s Q2 refining margins of $6.34 billion nearly doubled from $3.28 billion year-over- year, driving a surge in the refining margin per barrel to $23.00. The ability to quickly export into supply-short markets significantly benefits US refinery profitability. Reduced crude runs at Chinese refineries are having a surprisingly large effect on global refined-product markets, and this is an important part of why the US Energy Information Administration is expecting strong refinery profitability in the US to the end of the year. Besides diesel, jet fuel is currently a key contributor to strong refinery profitability, particularly because the international jet-fuel market has become tight. Higher profits from regulatory-driven renewable fuels are contributing to refinery profitability in several refining regions. For example, Neste Oil’s renewable products sales margin reached $1,223/ton, and sales volumes exceeded 1.0 million tonnes in Q2 2026, with oil products total refining margin at $25.8/barrel. In comparison, 95-97% utilisation rates at US refineries can nonetheless indicate that the risk of unplanned outages could immediately lower output by more than 500,000 bpd. Sustainable aviation fuel (SAF) is becoming an increasingly important growth engine for the renewable fuels market, particularly for renewable diesel producers and refiners that can convert existing hydroprocessing assets to SAF production. The most important point is that SAF creates a higher-value outlet for renewable feedstocks that might otherwise go into renewable diesel. In fact, SAF creates a new premium market for renewable molecules. It is no secret that conflicts in the Middle East and Europe could further exacerbate world oil stockpiles, which are already at historic lows. These lows cause underly- ing structural exposure affecting industry planning further down the refining and petrochemical value chain, including olefins, ammonia, and fertilisers. Against this backdrop, oil-to-chemicals margins compression has been affected by external market pressure in certain refinery regions, while other markets con - tinue investing further downstream in the petrochemical value chain. For example, Pemex Director General Víctor Rodríguez Padilla announced earlier this year a $21.2 billion investment plan for 2026 as part of Mexico’s Infrastructure Plan 2026-2030. One of the most relevant drivers of profitability trends can be seen in Phillips 66’s Q2 2026 earnings report, where adjusted results were lifted by almost 300% year-on-year as refining margins roughly doubled. That profit surge funded further debt reduction, sizeable dividends, and buybacks. Phillips 66 projects $136.2 billion revenue and $7.3 billion earnings by 2029. Looking ahead to 2027, refinery profitability is projected to be less exceptional than 2026, but still potentially healthy. What supports refinery margins today could change in 2027. However, overall, diesel and jet fuel cracks, Chinese refinery utilisa - tion rates, and worldwide refinery capacity additions and closures all weigh into any profitability model. Rene Gonzalez
PTQ (Petroleum Technology Quarterly) (ISSN No: 1632-363X, USPS No: 014-781) is published quarterly plus annual Catalysis edition by EMAP and is distributed in the US by SP/Asendia, 17B South Middlesex Avenue, Monroe NJ 08831. Periodicals postage paid at New Brunswick, NJ. Postmaster: send address changes to PTQ (Petroleum Technology Quarterly), 17B South Middlesex Avenue, Monroe NJ 08831. Back numbers available from the Publisher at $30 per copy inc postage.
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PTQ Q4 2026
Rethinking Old Problems
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Revamp projects are difficult. Limitations imposed by plot space, congested pipe racks, and outdated equipment, to name a few, present unique challenges. Solutions that rely on excessive margins or comfortable designs lead to overspend. Now more than ever, process designers must find solutions that do more with less. P roven M ethods There is growing awareness that better scope definition earlier in the engineering phase saves time, reduces overall engineering cost, and leads to more successful projects. There is no argument that work completed during Conceptual and Feasibility phases is critical to getting a project on the right path. Engineers at Process Consulting Services, Inc. have developed a proven approach that makes the most of this precious time. At site, PCS engineers coordinate rigorous test runs, much of it through direct field measurements. Data collected is invaluable and often leads to low hanging fruit or hidden gems. Some refinery equipment performs better than design, and for various reasons others perform worse. Good test run data allows seasoned engineers to quickly identify what equipment needs investment and what equipment can be exploited. This way, solutions are developed that direct capital expense in the right areas and overspending is avoided. In one example, pressure drop measurements of a long crude oil transfer pipe showed the line could be reused, saving millions of dollars. Contact us today to learn how PCS’ proven methods can help you do more with less in your next revamp.
Projections for global supply and demand of refined products vary greatly depending on the pace of technological progress and degree of government policy enforcement associated with reducing greenhouse gas emissions. Without major advances in technology, it is hard to imagine a future without conventional fossil fuels over the next decade or two. Based on history, continued rationalization of refining assets is likely. Small, low-complexity refineries will struggle, while large, complex ones will thrive. Capacity creep through gradual improvement of refining units will continue to be a differentiating characteristic for remaining players. Focused revamps will play a critical role. Post-pandemic, inflation and a shortage of skilled construction labor have dramatically increased costs for refinery revamps. It is becoming increasingly difficult for many projects to meet corporate return on investment thresholds.
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pt q&a
More answers to these questions can be found at www.digitalrefining.com/qanda
Q How can refiners increase petroleum coke production? A Al Geraskin, Senior Director, Integrated Global Services (IGS), al.geraskin@integratedglobal.com Increasing petcoke production is often less about expand- ing capacity and more about eliminating operational bottle- necks that reduce coker availability and throughput. Many delayed coker units (DCUs) are constrained by fouling, thermal inefficiencies, or equipment reliability rather than by their design capacity. One common limitation is fouling in the heater convec- tion section. As deposits build up, heat transfer efficiency declines, and operators must increase firing rates to main - tain process temperatures. Higher firing rates can acceler - ate tube coking, decreasing operating cycles and increasing the frequency of decoking shutdowns. Maintaining clean heat transfer surfaces through effective inspection and cleaning strategies can improve thermal efficiency while extending run lengths. Another opportunity lies in improving heat distribution within the radiant section. Uneven heat flux across heater tubes can create local hot spots that promote premature coke formation. Technologies such as engineered high- emissivity coatings can help deliver more uniform heat transfer, reducing tube skin temperatures and extending the time between decoking events. Reliability of downstream equipment is equally impor - tant. Fractionators, scrubbers, and amine systems exposed to corrosive or high-temperature environments can become production constraints if degradation leads to unplanned maintenance. Targeted repairs or on-site alloy upgrades can extend equipment life while improving resistance to corrosion and erosion without requiring complete vessel replacement. Finally, ageing coke drums remain a significant challenge for many refiners. Where replacement is difficult because of cost, logistics, or outage constraints, engineered repair and restoration solutions may provide a practical way to restore structural integrity and maintain reliable operation. Ultimately, increasing petcoke production depends on improving overall unit availability. Small gains in heater efficiency, longer operating cycles, and greater equipment reliability can combine to deliver meaningful increases in annual production without major capital investment. Q How can the industry avoid failures to thermal sys - tems, such as heater faults? A Larry Emch, Furnace Efficiency SME, Integrated Global Services (IGS), larry.emch@integratedglobal.com The industry’s approach to thermal system reliability is shifting from reactive maintenance to condition-based and predictive asset management. A key priority is maintain- ing efficient heat transfer. Fouling in convection sections
reduces thermal efficiency, increases fuel consumption, and raises tube metal temperatures, all of which acceler - ate equipment degradation. Regular assessment of fouling rates and cleaning strategies should be considered part of routine reliability planning rather than simply an outage activity. Understanding heat distribution is equally important. Uneven heat flux within fired heaters can create localised hot spots that promote tube coking, creep, and premature failure. Increasingly, refiners are using advanced modelling, infrared inspections, and surface engineering technologies to better manage heat transfer and reduce thermal stresses across heater components. Many heaters and associated pressure vessels continue to operate beyond their original design life, often under more severe process conditions than originally anticipated. Periodic fitness-for-service assessments and selective materials upgrades can improve resistance to corrosion, erosion, and high-temperature degradation while extend - ing asset life without wholesale replacement. Finally, digital inspection tools and robotics are expand- ing the industry’s ability to inspect and maintain equipment safely and more frequently. Improved access to condition data allows maintenance activities to be prioritised based on asset health rather than fixed schedules, reducing both operational risk and unnecessary downtime. No single technology eliminates heater failures. Instead, the greatest improvements come from combining good operational practices, effective inspection programmes, appropriate materials selection, and targeted maintenance interventions. Together, these measures can improve reli- ability, reduce energy consumption, and extend the safe operating life of thermal systems. Q What advancements to online catalyst monitoring tools benefit refinery operations? A Nattapong Pongboot, Project Leader, R&D Solutions, Avantium, Nattapong.pongboot@avantium.com Previously, refinery operators and engineers manually programmes, appropriate materials selection, and targeted maintenance interventions No single technology eliminates heater failures. Instead, the greatest improvements come from combining good operational practices, effective inspection
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www.digitalrefining.com
monitored the catalyst performance and behaviour using distributed control system (DCS) or process monitoring tools, such as PI. The process of compiling data alone is already time-consuming, even before data review, opti- misation, or troubleshooting can start. Sometimes, the catalyst suppliers are consulted, and the turnaround time further delays the process. To make matters worse, the problem might have been overlooked due to overwhelming tasks or human fatigue/error, leading to sub-optimal cata- lyst performance or safety issues. As an example, the hydrogen consumption of a hydro- cracking unit is unusually high and keeps increasing, which is an indication of uncontrolled chemical reactions or local- ised temperature runaway. While this might be detected by a DCS operator during a normal/smooth refinery operation, the unit operator could be busy handling the feed fluctua - tion from upstream units, such as the vacuum distillation column, to the point that this unusual catalyst behaviour is missed, potentially leading to a full-scale temperature run- away, unit shutdown, production loss, or fatality. In modern days, refinery operators and engineers have the privilege of accessing online advanced data monitoring tools to assist with data gathering, processing, and analy- sis. In addition, the plant data can be further augmented with catalyst performance or kinetic databases. These assistant tools greatly unload the burden of rou- tine tedious tasks, so the operators and engineers can spend more time on more valuable duties, such as catalyst performance optimisation, troubleshooting, and ensuring safe operation. Some operational reasoning tools can also detect anomalies and suggest preventive actions to opera- tors, while providing a strategy for optimising catalyst per- formance on a real-time basis. Going back to the same hydrocracking example, an AI-based operational reasoning tool can continuously gather and process the plant data, then automatically define the hydrogen consumption baseline based on the feed rate, feed quality, catalyst life, and hydrocracking con- version. When the hydrogen consumption starts to deviate from the baseline, it can automatically notify the operator to take preventive action, i.e., reducing conversion or feed rate, without requiring intensive human monitoring. While originally intended for continuous process monitor- ing, optimisation, and troubleshooting, the online catalyst monitoring tool greatly helps improve overall manpower utilisation and refinery operation. A Melissa Clough Mastry, Director, Global Technology and Technical Services, BASF, melissa.mastry@basf.com, and Grant Severyn, Senior Technical Service Engineer, BASF, grant.severyn@basf.com The most significant advancement in online catalyst moni - toring is the convergence of plant data, catalyst perfor- mance analytics, and predictive modelling into a single decision-support ecosystem. Historically, refiners relied on periodic laboratory analyses and engineer interpretation to understand catalyst performance. Today, advances in connectivity, automation, and AI are enabling continuous performance monitoring and faster optimisation decisions.
One example is the growing use of automated fluid cata - lytic cracking (FCC) performance prediction tools. Rather than waiting for monthly reconciliations or catalyst evalu- ations, refiners can combine unit operating data, catalyst inventory information, and process models to continuously estimate catalyst activity, selectivity, and expected yields. A refinery targeting maximum propylene production, for example, can quickly evaluate whether a decline in olefin yield is being driven by catalyst age, feed quality changes, metals accumulation, or operating severity. In some cases, advanced predictive tools can identify a developing metals-related selectivity loss weeks before it becomes obvious in routine performance reviews, allowing refiners to adjust catalyst strategy proactively rather than reactively. What once required days of engineering analysis can increasingly be completed in near real time. The rapid expansion of data connectivity is also deliver- ing substantial benefits. Modern platforms can integrate laboratory results, process historians, advanced process control (APC) systems, and refinery planning tools through application programming interfaces (APIs), secure data transfers, and industrial analytics platforms to create a single source of truth for catalyst performance. The availability of information has improved as well. Digital customer portals such as BASF’s proprietary Catalyst Connect provides refiners with centralised access to shipment information, certificates of analysis (COAs), E-cat analytical results, and historical catalyst data. Instead of searching through emails, spreadsheets, and archived reports, engineers can access critical catalyst information through a single interface, improving visibility and accelerating troubleshooting and decision-making. AI and advanced analytics are further accelerating this transformation. The industry is increasingly leveraging AI-assisted mod- elling tools to evaluate large and complex FCC data sets, identify emerging performance trends, and rapidly gener- ate visualisations that help engineers focus on the most impactful opportunities. Rather than spending valuable time collecting and organising data, engineers can spend more time evaluating options and implementing improvements. Perhaps the most important development is that catalyst monitoring is evolving from reporting what happened to helping refiners decide what to do next. Many of these capa - bilities required to support this approach are already being applied, including automated performance predictions, digital customer portals, integrated refinery data streams, advanced modelling tools, and expert-driven analytics. When these tools are combined with catalyst expertise and refinery operating knowledge, they enable faster iden - tification of opportunities, more proactive troubleshoot - ing, and more informed catalyst and operating decisions. They also accelerate catalyst reformulation and optimisa- tion by rapidly evaluating catalyst performance, predicting outcomes, and identifying the most effective formulation adjustments to changing refinery objectives and operating conditions. The ultimate value is not more data, but better decisions that improve yields, profitability, and operational reliability.
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PTQ Q4 2026
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A Disha Sharma, Strategic Marketing Manager, Performance Catalyst Solutions, W. R. Grace & Co. (Grace) disha.sharma@grace.com It has been 84 years since the start-up of the first com - mercial FCC unit. While much has stayed the same as these critical processes stand the test of time, one notable area of advancement has been the digitalisation of analysis and monitoring tools. As FCC and hydroprocessing units grow more complex and decision windows shrink, refinery performance increas - ingly depends on converting large volumes of catalyst and process data into timely, actionable insight. To that end, an integrated portfolio of digital tools can improve data visibil - ity, strengthen decision-making, and shorten the path from data to action. For example, the proprietary e-Catalysts.com platform provides a secure workspace purpose-built for FCC teams. Rather than functioning as a static repository, the platform brings sample data, analysis, and operational insights into one environment, allowing operators to track samples across E-cat, fines, feed, and slurry streams, access COAs instantly, and visualise historical and current trends. Another example of a digital tool benefiting refinery oper - ations is Grace’s E-cat Alerts, a proactive monitoring layer that builds on e-Catalysts.com. Automated, rules-based alerts continuously track critical equilibrium catalyst prop - erties, flagging new 365-day highs or lows and deviations beyond defined tolerances, surfacing meaningful changes without manual data review. Recently, the same framework has been extended to fines samples, with globally suggested and unit-tunable tolerances on specific fines properties. This closes a long- standing monitoring gap, helping teams detect catalyst loss, attrition events, and regenerator-side issues days ear - lier than routine review cycles would allow. For deeper integration with refinery operations, the E-cat API enables refiners to securely pull E-cat testing results into their own analytics environments, eliminating manual handling and connecting catalyst insights with plantwide operating and economic data. Digitalisation is no longer a bolt-on to catalyst service; it is becoming the operating layer through which that service is delivered. A Lars Gottlieb Jørgensen, Product Owner, Digitalisation, Topsoe, LJOR@topsoe.com Online catalyst monitoring has evolved from simple data logging into a genuine collaboration platform between refiners and catalyst vendors. This shift is where the real operational value now lies. Closer collaboration through shared data – from reactive to proactive service Historically, a process engineer had to pull data from the DCS or historian, format it, and send it to the catalyst ven - dor before any review could happen. Consequently, cata - lyst performance data lived in disconnected spreadsheets, emails, and local databases, with the vendor’s service engineer receiving data only after the fact during periodic reviews or troubleshooting calls.
Modern online monitoring platforms automate this data flow, relieving the refinery engineer of manual work, giving both parties a shared, real-time view of unit performance. This shared view closes the gap between the refinery engi - neer and the catalyst vendor’s service engineer, as both sides work from the same live picture of the unit rather than reconciling data long after the fact. When data is continuously visible, rather than reviewed only periodically or when something goes wrong, vendor service engineers can spot deviations, such as activity decline, selectivity shifts, and unexpected temperature pro - files as trends emerge, not after they become problems. In addition, data visualisations have become richer and more sophisticated, giving refiners more intuitive and action - able insights without the need to build custom analysis in- house. These visualisations are reinforced by automated alert systems that guide attention to what matters most. Data visualisations have become richer and more sophisticated, giving refiners more intuitive and actionable insights without the need to build custom analysis in-house Together, these features enable near-real-time detection of subtle performance changes, such as activity decline, selectivity shifts, and unexpected temperature profiles, allowing refiners to take faster corrective action. Documented, historical, streamlined communication Centralising monitoring data also centralises communi - cation. Instead of insights being scattered across email threads and call notes, recommendations, observations, and decisions are logged directly against the relevant data and timeline. This centralisation creates a persistent, audit - able history that new engineers, shift teams, and plant managers can reference later, facilitating knowledge trans - fer and traceability of past decisions. Predictive insight in the refiner’s hands Perhaps the most significant shift is putting predictive capa - bility directly into the refiner’s own workflow, rather than keeping it solely as a vendor-side analysis. Trend-based pro - jections, such as remaining catalyst life, expected deactiva - tion curves, and time-to-next regeneration, allow operators to make faster, better-informed decisions on their own time - line, without waiting for the next scheduled vendor review. These predictive capabilities can help shorten the decision loop considerably, especially when evaluating operational changes, feed adjustments, or turnaround planning. Together, these advancements turn catalyst monitoring from a periodic diagnostic exercise into a continuous and shared decision-support process, benefiting run length, reliability, and the overall refiner-vendor relationship.
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PTQ Q4 2026
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Mitigation of ammonium chloride salt formation in FCC main fractionator
Commercial case study on the reduction of saline deposits in continuous operation of the FCC unit
Adilson Cavalheiro Borges Gutierres FCCSA Carlos Alberto Rivera Corredor and Manuel Julian Ardila Pimiento Ecopetrol Eric Rutan and Cliff Avery Ketjen Corporation
T he deposition of ammonium chloride (NH₄Cl) salts in the main fractionator of fluid catalytic cracking (FCC) units is a significant operational issue, associated with increased pressure drop, loss of separation efficiency, and the risk of under-deposit corrosion. The authors present the analysis of an industrial case in an FCC unit where recurrent formation of salt deposits was observed in the overhead system of the fractionator, directly affecting operational performance. The phenomenon was evaluated based on the behaviour of differential pressure, chloride balance, and operating conditions of the system. Two operational periods with significantly different behaviours were compared. In the first case, the unit showed high chloride levels, persistent deposit formation, and reliance on mitigation strategies, such as water injec- tion and the use of dispersants. In the second case, after adjustments to the system’s chloride balance, a substan- tial reduction in salt formation was observed, along with the elimination of the need for chemical mitigation and an improvement in fractionation efficiency. The results indicate that controlling the chloride balance, including all potential sources within the unit, is a key factor in mitigating the formation of ammonium chloride (NH₄Cl) and improving overall distillation performance in the main fractionator. Salt deposits The formation of salt deposits in overhead systems is a widely documented phenomenon in refining units, particularly in those where chlorine species and nitrogen compounds coexist. In FCC units, the main fractionator represents one of the most sensitive areas to this type of problem due to the combination of thermal gradients, partial condensation of hydrocarbons, and the presence of reactive species in the vapour phase. Among the commonly observed deposits, NH₄Cl is one of the most critical. This compound can be formed in the vapour phase from the reaction between ammonia (NH₃) and hydro- chloric acid (HCl). It subsequently deposit in areas where the temperature falls below its thermodynamic stability point. The formation and deposition of NH₄Cl depend mainly on the partial pressure of its precursors and on the system’s
thermal profile, with the behaviour of the fractionator over- head being especially important. From an operational point of view, this phenomenon usu- ally manifests itself through: • Progressive increase of the differential pressure in the overhead system. In industrial practice, the control of these deposits is usu- ally addressed through mitigation strategies, such as water injection and the use of dispersant chemicals. However, these measures do not address the root cause of the problem; rather, they aim to limit its effects on the operation. In this context, the analysis of the chloride balance in the unit plays a central role. Chlorine sources may include the feedstock, internal streams, operational contaminants, and the catalyst. The interaction between these sources and the operational conditions defines the propensity for NH₄Cl formation. Further analysis of this article’s industrial case of an FCC unit shows where salt formation reduction was achieved through a change in catalyst technology, highlighting the impact of the chloride balance on the behaviour of differen - tial pressure and main fractionator performance. Main sources of FCC unit chlorides • Reduction of separation efficiency. • Operational restrictions in the unit. • Risk of corrosion under-deposit. Formation of NH₄Cl salts in FCC units is directly related to the availability of precursor species in the system, par- ticularly ammonia (NH₃) and chlorine compounds that can generate hydrochloric acid (HCl). Ammonia is primarily produced from the thermal decomposition of nitrogen-con- taining compounds present in the feed. On the other hand, chlorine sources can be multiple and, in many cases, simul- taneous, making it difficult to identify a single cause for the formation of salts. The main sources of FCC unit chlorides include: • Fresh feed : Presence of residual inorganic salts due to lim- itations in the desalting process. • Internal streams: Incorporation of slops or recycled mate- rials containing chlorides. • Operational contamination: Ingress of saline water or fail- ures in separation systems.
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corrosion in tower internals, domes, heat exchangers, and associated piping. The impact of the phenomenon extends to downstream equipment. Salt deposition on heat transfer surfaces reduces thermal efficiency, affecting the performance of critical equipment such as the depropaniser tower reboiler and lim- iting propylene glycol (PGR) recovery. Likewise, the pres - ence of salts in the process streams can cause premature mechanical seal failures and contribute to deposition in the wet gas compressor, affecting its performance. At the global level, the build-up of deposits can increase pressure in the flash zone, requiring higher bottom tempera - tures to maintain the yield of products such as light cycle oil (LCO), worsening fouling conditions in the slurry circuit, and affecting the unit’s heat balance. Given the multiplicity of impacts generated by salt for - mation and deposition, its management should not be approached solely from a corrective perspective. Strategies such as water washing or the use of dispersants can partially mitigate the problem, but they do not eliminate its root cause (see Figure 1 ). In this context, effective control of the phe - nomenon requires a preventive approach, based on continu- ous monitoring of process variables and management of the system’s chloride balance, including all its potential sources. Case study: Mitigating salt formation With the aim of analysing the operational impact associated with salt formation in the FCC unit main fractionation sys - tem, a case is presented based on the operation of a Latin American refinery, where this phenomenon began to emerge progressively as of 2019. The FCC unit, designed for processing heavy feeds with high operational flexibility, plays a central role in naphtha production, with a fractionation scheme that requires strict control of thermal and separation conditions. In this context, the main fractionator constitutes a critical point for the unit’s operational stability. Starting in 2019, a sustained increase was observed in the differential pressure in the upper section of the fractionator, particularly in the area associated with cracked naphtha handling. This behaviour was accompanied by operational evidence consistent with salt deposition, including the pres- ence of salts in wash streams and the increasing need for interventions to restore operating conditions. As the phenomenon progressed, the operational impacts intensified. Restrictions in vapour-liquid traffic were recorded in the overhead section, affecting separation efficiency and causing deviations in the distillation cuts, especially between light and heavy naphtha. Under more severe conditions, the accumulation of deposits led to episodes of instability in the reflux system and an increased tendency for heavy hydro - carbons to be carried over into lighter streams. The problem was not limited to the fractionator. The prop- agation of the phenomenon to downstream equipment gen- erated additional impacts on the unit’s operation. A decrease in heat transfer efficiency was observed in exchangers asso - ciated with the heavy naphtha circuit and in the reboiler of the depropaniser tower, affecting product recovery and the thermal balance of the system.
• Operating conditions: Carryover or the accumulation of species in certain areas of the system. • Catalyst: When technologies based on chloride-containing binder are used. The combined effect of these sources determines the chloride balance in the unit, which is a critical factor in the propensity for NH₄Cl formation. In practice, monitoring the chloride content and its correlation with operational varia- bles, such as the differential pressure in the overhead sys- tem, is a key tool for identifying the phenomenon. Salt precipitation mechanism and operational impacts The formation of NH₄Cl salts in FCC units occurs mainly through the vapour-phase reaction between NH₃ and HCl: NH₃ (g) + HCl (g) ⇌ NH₄Cl (s) The equilibrium of this reaction depends on the partial pressure of the reactants and the temperature of the system. Under typical operating conditions, NH₄Cl can form in the vapour phase and subsequently deposit when the system reaches temperatures below its thermodynamic stability limit. This phenomenon occurs primarily in areas where there is a progressive cooling of the vapours, such as the top of the main fractionator and the overhead lines. Under these con- ditions, the combination of the thermal profile and the avail - ability of precursors determines the propensity for deposit formation. From a thermodynamic standpoint, the precipitation of NH₄Cl is governed by the product of the partial pressures of NH₃ and HCl. In systems where NH₃ is in relative excess, salt formation is predominantly controlled by the availability of chlorides. In this scenario, increases in chloride content result in a direct shift of the equilibrium towards the formation of deposits. Once formed, NH₄Cl salts deposit on metal sur - faces, even in the absence of a visible liquid phase, and due to their high hygroscopicity, they can create highly corrosive environments. From an operational standpoint, their accumulation causes a progressive increase in the pressure drop (ΔP) in the top section of the fractionator, reducing the active area of the trays and deteriorating the vapour-liquid contact. As a result, phenomena such as liquid entrainment (flooding), reflux instability, and loss of separation efficiency occur. Furthermore, the presence of salts promotes the formation of sour solutions in the presence of moisture, causing localised Figure 1 Washing effluent from the pumparound pump and HCN product
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Likewise, recurring failures were reported in rotating equipment, particularly in mechanical seals of pumping systems, as well as risks asso- ciated with the performance of the wet gas compressor, demonstrating that the issue extended beyond the fraction- ation system and affected the unit’s overall reliability. From an operational standpoint, controlling the phenomenon involved the implementation of recurring
0.4 0.5 0.6 0.7 0.8 1 0.9 1.1
1.06
1.05 1.06
1.03 1.00
0.95 0.94
0.83
0.80
0.78
0.76 0.74
0.75
0.69 0.68 0.70 0.71
0.63
Month
Figure 2 Fractionator overhead differential pressure
corrective measures. Among them were online washing of the overhead system, increasing the operating temperature to move conditions away from the dew point, and injecting salt dispersants. However, these actions proved insufficient to eliminate the recurrence of the problem, only temporarily mit- igating its effects. As a result, the unit operated under restric- tions, including limitations on the processed feed, increased operating costs, and a higher frequency of interventions. Operational comparison of the FCC unit For this analysis, two distinct operating periods were con- sidered, in which the impact of salt formation, specifically NH₄Cl, on the operation of the main fractionator and the quality of light naphtha was evaluated. Since 2019, the unit has recurrently presented problems associated with the formation and accumulation of salts in the fractionator overhead system. Starting in November 2021, coinciding with the change of catalyst supplier, a pro- gressive reduction in the differential pressure in the upper section of the fractionator began to be observed, as shown in Figure 2 . This behaviour marked a turning point in the unit’s operation, as the decrease in ΔP occurred steadily, without the need for additional operational interventions. Consistent with this evolution, since December 2021 it was no longer necessary to continue injecting salt disper- sants or to carry out washes in the fractionator overhead system, representing a significant change from the behav - iour observed in previous years. This operational change, not associated with relevant modifications in the feed or operating conditions, prompted a more detailed analysis of the system, aimed at identifying possible variations in the chloride balance. In this context, the hypothesis of a possible contribution of the catalyst as a source of chlorinated species in the system was proposed. Based on this observation, the comparison between two operational periods was defined: a first period characterised by the recurrent presence of deposits in the fractionator overhead system, and a second period in which the phenom- enon ceased to occur, allowing the observed changes in the unit’s performance to be assessed comparatively. Chloride balance analysis Chlorides measurements in the acid water streams dur - ing both periods clearly show the impact of the system’s
Chloride balance of the unit
Balance of Cl (NH₄)
Period 1
Period 2
Feed, kg/d
13.2 27.2 15.4
7.9 8.7 0.8
Sour, water kg/d
Delta, kg/d
Table 1
behaviour on salt formation, accumulation, and removal. During the first period, a higher presence of chlorides in the feed is observed compared to the second period (see Table 1 ). However, the main difference is evident in the chloride output through the sour waters, which is significantly higher than the input from the feed. This imbalance indicates the existence of an additional source of chlorides in the system, as well as a dynamic behaviour characterised by the accumulation of salts in the fractionator and their subsequent release into the process streams. This period coincides with the operation of the unit using a catalyst formulated with a chloride-contain- ing binder, which incorporates chloride-based compounds in its technology. Under unit conditions, these compounds can release chlorinated species into the system, contribut- ing to an increase in the chloride inventory beyond what is expected solely from the feed quality. In contrast, during the second period, there is an almost direct correspondence between the chlorides present in the feed and those removed through the acid waters. The low delta value indicates a system without significant salt accu - mulation, with a chloride balance close to closure and stable operation. This behaviour is consistent with the elimination of the need for corrective actions, since from the end of 2021 it was no longer necessary to carry out washes in the fractionator overhead or maintain salt dispersant injection, demonstrat- ing a sustained deposit-free operating condition. Impact on light naphtha quality The performance of the fractionation system was directly reflected in the quality of the light naphtha stream (see Table 2 ). During the first period, an atypical distribution of sulphur compounds is evident, with a significant fraction of sulphur present above the final boiling point (FBP). This behaviour
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PTQ Q4 2026
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Quality of the light naphtha
60.00 50.00 52.00 54.00 56.00 58.00 62.00 64.00
Light naphtha
Period 1
Period 2 -25.8% -81.7% -19.7% +12.2% +15.1%
Total sulphur, ppm Mercaptans, ppm Thiophenes, ppm
Base Base Base Base Base 59% 41%
Benzothiophenes, ppm
FBP naphtha, °F
Sulphur < FBP wt% Sulphur > FBP wt%
97%
3%
Table 2
reflects an inefficiency in the separation of the fractions, associated with the degradation of vapour-liquid contact in the upper section of the fractionator due to deposit build-up. This operational deterioration favours the carryover of heavier hydrocarbons into the light naphtha stream, affecting both the product quality and the process selectivity. In con- trast, during the second period, a significant improvement in sulphur distribution is observed. Despite the increase in the naphtha FBP, the fraction of sulphur present above this point decreases drastically, falling from 41% to just 3%. This behaviour is consistent with a recovery in the per- formance of the fractionation system, allowing for a more efficient separation between the light and heavy naphtha streams (see Figure 3 ). Additionally, this improvement in separation efficiency allowed for an increase in light naphtha yield, achieving volume increases of up to 5%, demonstrat- ing the direct impact of deposit removal on the overall per- formance of the unit. Conclusions The results of this study show that the formation of ammo- nium chloride (NH₄Cl) salts in the main fractionator of FCC units should not be treated solely as an operational problem, but as a systemic phenomenon directly related to the chlo- ride balance of the system. First operating period: Operation under severe salt fouling. During the first period, the unit had a recurring history of fouling in the fractionator overhead, characterised by the build-up of salt deposits that directly affected operational stability. This condition required: • Continuous use of salt dispersants, with an accumulated cost exceeding $700 million (COP). • Frequent washing with water in the top system, weekly for ΔP control. • Feed reduction during interventions, impacting operational continuity. • Increased frequency of failures in mechanical seals of pumping equipment, with average repair costs around $45 million (COP) and upgrade costs close to $140 million (COP) per event. From a process performance standpoint, sulphur speci- ation studies showed clear inefficiency in the separation zone between heavy naphtha and light naphtha, with sul- phur compounds being carried over to the fractionator over- head. This behaviour is consistent with the degradation of
Figure 3 Naphtha performance
vapour-liquid contact caused by the presence of deposits on the tower internals. In terms of chloride balance, this period was characterised by an open behaviour, with chloride output exceeding the input from the feed, indicating the existence of additional sources within the system. This scenario coincided with operation using a catalyst formulated with a chlorinated sol-alumina-based binder, whose contribution to the sys- tem’s chloride inventory became evident from the compara- tive analysis of the operating data. Second operating period: Elimination of the phenomenon and sustained stability. The transition to the second period, after replacing the catalyst with a technology free of chlorin- ated compounds, marked a substantial change in the unit’s behaviour. From this moment on, immediate and sustained operational improvements were observed: • Complete elimination of the need for continuous injection of salt dispersants. • Elimination of the periodic washes in the fractionator overhead. • Progressive reduction and stabilisation of the differential pressure (ΔP). • Improvement in the reliability of rotating equipment, with a reduction in failures associated with salts. • Sustained operation without evidence of deposit build-up. It is worth highlighting that this condition was not tem- porary. Operation free of salt build-up in the fractionator overhead system has been consistently maintained to date (2026), confirming the stability of the new operating state achieved and the resolution of the root cause of the problem. From the process perspective, a clear recovery of fraction- ation efficiency was observed. Light naphtha showed an increase in its FBP, accompanied by a sulphur distribution consistent with effective separation, eliminating the carry- over of heavy compounds to the overhead. Additionally, the improvement in separation efficiency allowed for an increase in the volumetric yield of light naphtha by up to 5%, reflect- ing a direct impact on the unit’s profitability. Operational implications and lessons learned This study shows that the strategies traditionally used in the industry, such as dispersants, frequent washes, or
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PTQ Q4 2026
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