PTQ Q3 2023 Issue

REFINING GAS PROCESSING PETROCHEMICALS ptq Q3 2023

HIGHER DIESEL YIELDS

FRACTIONATOR OPTIMISATION FCC CO-PROCESSING

H 2 FIRING

UPDATE YOUR SUBSCRIPTION REGISTER FOR A PRINT OR DIGITAL ISSUE TO MAKE SURE YOU CONTINUE RECEIVING A REGULAR ISSUE OF PTQ ANY QUESTIONS? REGISTER CONTACT US CLICK HERE

Prepare for Takeoff

Click here to check-in

Discover mature and reliable technologies to produce Sustainable Aviation Fuel (SAF)

Q3 (Jul, Aug, Sep) 2023 www.digitalrefining.com ptq PETROLEUM TECHNOLOGY QUARTERLY

3 Robust prospects in fuels and petrochemicals Rene Gonzalez

5 ptq&a

13 Improve energy efficiency of your hydrocracking unit Kiran Ladkat, Jan De Ren and Kiran Kashibhatla Honeywell UOP

19 Focused revamp increases diesel and HVGO recovery Scott Golden, Tony Barletta and Steve White Process Consulting Services Ben C Miller CITGO

33 Proactively preventing reactor runaway events Jeff Johns Becht

39 Olefins production pathways with reduced CO2 emissions Christopher R Dziedziak and John J Murphy The Catalyst Group (TCG) 49 Using hydrogen in fuel to eliminate CO2 emissions in fired heaters Luke Glashan Wood 55 Structured catalyst reactor system for steam methane reforming Sanjiv Ratan and Bruce Boisture ZoneFlow Reactor Technologies LLC William Blasko and Wolfgang Spieker Honeywell UOP Florent Minette and Juray De Wilde Université Catholique de Louvain

62 Purifying and upgrading of waste plastics pyrolysis oils Artem Vityuk and Sanaz Norouzi BASF Corporation 66 Maximising renewable feed co-processing at an FCC Stefan Brandt and Drey Holder W. R. Grace & Co. Gary Lee Parkland

70 Spent caustic treatment and reuse James G Aiello Merichem Company

75 Predicting hydrotreater performance while co-processing vegetable oil Eelko Brevoord Catalyst Intelligence Tiago Vilela Avantium 81 Debottlenecking product recovery using product pair distillation: Part II David Kockler Dividing Wall Distillation and Separations Consulting, LLC

91 Reducing emissions while increasing refinery margin Bernd Van Den Bossche Qpinch

97 Technology in Action

Cover Crude/Vacuum Unit at CITGO Petroleum Corp. Lake Charles Refining Complex

©2023. The entire content of this publication is protected by copyright. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means – electronic, mechanical, photocopying, recording or otherwise – without the prior permission of the copyright owner. The opinions and views expressed by the authors in this publication are not necessarily those of the editor or publisher and while every care has been taken in the preparation of all material included in Petroleum Technology Quarterly and its supplements the publisher cannot be held responsible for any statements, opinions or views or for any inaccuracies.

www.decarbonisationtechnology.com www.digitalrefining.com

REVAMP TO THRIVE IN THE NEW REALITY

The global economic challenges impact product demand and skew product slates. As you continue to deal with the challenges in the present, its critical to think about long-term solutions. Shell Catalysts & Technologies, has solutions to enable you to make smart investments while preserving cash through revamping, reconfiguring, or optimising your existing assets. Our experts co-create tailored solutions for current units while keeping your margins in mind — ensuring the investments you make right now can help you maintain your competitive advantage into the future. Learn more at catalysts.shell.com/revamps

Vol 28 No 4 Q3 (Jul, Aug, Sep) 2023 ptq PETROLEUM TECHNOLOGY QUARTERLY

Robust prospects in fuels and petrochemicals

O pportunities for higher margins in refinery and petrochemical markets seem to indicate that a compound annual growth rate (CAGR) exceeding 4-5% at the time of writing could prevail in the near term. But what about the long term? The Indian Ministry of Petroleum and Natural Gas (MoP&G) recently projected that India’s primary energy demand is expected to grow at a CAGR of 4.2% to 2040. In parallel, the MoP&G reported that Indian refining capacity has increased from 62 million tons since the late 1990s to 240 million tons. Downstream industry fundamentals and higher margin opportunities in the fuels market are better than expected in some regions. Joe Gorder, CEO of Valero, a US-based independent refiner, recently said it expects refining fundamentals to stay supported by several factors, including a continued increase in product demand. To capture higher margins associated with the tight supply of light product inven- tories, some facilities are delaying scheduled maintenance to continue operating at near maximum capacity. Many refineries are operating at 93+%, but not as high as the 102+% operating rates reported at some facilities in 2022. Some fuel products increasing in demand are diesel and aviation fuel, including sustainable aviation fuels (SAF). The global aviation fuel market is projected to grow from $351.85 billion in 2022 to $654.79 billion by 2029, at a CAGR of 9.3% in the forecast period 2022-2029. Boeing announced it would double its SAF procurement for the year, buying 5.6 million gallons of the fuel from producer Neste. However, Boeing’s CEO David Calhoun recently warned that SAF would “never achieve the price of conventional jet fuel,” downplaying hopes for the technology in the sector. The worldwide maritime industry is also expanding in tonnage. For example, China’s National Shipbuilding Industry Association reported that China’s total ship- building output in the period between January and April amounted to 12.8 million deadweight tonnage (DWT), up 9.3% year-over-year, increasing demand for low- sulphur marine diesel and LNG-powered ships (to a lesser extent). Even as the fuels market continues to deliver value, long-term expectations are for nearly flat fuels margins. Some regions are finding it more lucrative to switch to naphtha-based feedstock production for the petrochemicals market (such as ethyl- ene and propylene). While 2022 may have seen the highest profits in the fossil fuel industry’s history, IEA’s Chief Economist Tim Gould emphasised that the industry has focused more on returning capital to shareholders than investing in long-term expansion-related Capex. Higher Capex is needed for chemical co-processing of biomass-based feedstocks through upgraded refinery assets, along with petro - chemical value chain expansion (olefins, polymers). For example, innovation in high- performance polymers presents new opportunities for the global plastic industry. In Europe, EU regulatory rulings on the use of recycled content in plastics packag- ing will help drive the market. Its uptake avoids greenhouse gas emitting incinera- tion of plastic marine and land debris. Converting waste plastics to circular plastics seems a win-win proposition considering the current demand for polymers like poly- propylene. However, wide-scale commercialisation still needs to happen. A study from Smithers tracks how future growth at a CAGR of 5.5% will drive the polymer market from a value of $19.2 billion to $25.2 billion in 2024. Global PE capacity will reach 146.5 million mt/y by year-end, largely on additions in China and the US, according to S&P Global’s Petrochemical Analytics. Further to the study’s projections, global PE capacity is expected to grow another 7.7% to nearly 157.9 million mt/yr by 2024. Barring the potential for any unforeseen global crisis, the downstream value chain remains robust.

Editor Rene Gonzalez editor@petroleumtechnology.com tel: +1 713 449 5817 Managing Editor Rachel Storry rachel.storry@emap.com Editorial Assistant Lisa Harrison lisa.harrison@emap.com Graphics Peter Harper US Operations Mark Peters mark.peters@emap.com tel: +1 832 656 5341 Business Development Director Paul Mason sales@petroleumtechnology.com tel: +44 7841 699431 Managing Director Richard Watts richard.watts@emap.com Circulation Fran Havard circulation@petroleumtechnology. com

EMAP, 10th Floor, Southern House, Wellesley Grove, Croydon CR0 1XG tel +44 208 253 8695

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 Publisherat $30 per copy inc postage.

Rene Gonzalez

PTQ Q3 2023

CREATING JET FUEL FROM THIN AIR. Introducing Honeywell UOP eFining™. We are ready to make eSAF a reality today. Reliable, scalable and cost-effective, our latest technology enables the conversion of CO 2 into high yield, high quality eSAF. It also reduces greenhouse gas emissions by 88% compared to conventional jet fuel.* Learn more at uop.honeywell.com/efining

*Reduced GHG emissions is based on UOP carbon intensity analysis, derived from a 3rd-party study of bio-methanol production from organic waste and green hydrogen, in comparison to fossil fuels.

pt q&a

More answers to these questions can be found at www.digitalrefining.com/qanda

Q What are the optimal routes to valorisation of olefins- rich FCC unit and coker unit off-gas? A Carel Pouwels, Global FCC Specialist Light Olefins, Ketjen, carel.pouwels@ketjen.com Valorisation routes greatly depend on refinery configura - tions. FCC units that typically operate in ‘conventional’ gasoline mode are distinctly different from FCC units that operate in max propylene mode or even in very high sever - ity mode. Therefore, it depends on the level of observed olefins. Refiners that aim to maximise propylene, whereby propylene yields are achieved at 9 wt% or higher, com - monly operate a C 3 splitter. The amount of ethylene pro - duced may be too low for economic recovery, especially in an environment where gasoline demand is relevant. However, not only does ethylene yield count but so do the scale and capacity of the FCC unit. As refiners pivot to serve the petrochemical market, greater severity can drive both propylene and ethylene yields. In such cases, ethylene recovery may be used to enhance FCC prof - itability. For those refiners who doubt the economics of their own assets and question whether there is more potential, it is worthwhile to investigate the status quo. Benchmarking against industry peers, as illustrated in the following chart (see Figure 1 ), provides a health check and valuable insight into a refiner’s current position. To benefit optimally from such configurations, we strongly recommend working closely with partners to maximise the units in operation. It is advantageous to use the expertise of the licensor of process equipment and supplier of FCC cata - lysts to tune the operation conditions and reformulate to the optimal FCC catalyst. A Celso Pajaro, Head Engineered Solutions Refinery, Sulzer Chemtech, USA, chemtech@sulzer.com ‘Optimal’ routes depend on the off-gas stream flow rate, composition, and refinery configuration. FCC unit off-gas can be sent to a cryogenic unit to recover the residual C₃+ and the C₂/C₂=. The C₂/C₂= rich stream can be injected down - stream of the ethane cracking furnace, where ethylene will

be recovered, and the ethane will be returned to the furnace. This arrangement requires the removal of water and other residual impurities. If there is no steam cracker, recovering ethylene may not be profitable, and a conversion process is preferred. There are several processes in the market that convert olefins into aromatics or other processes that alkylate benzene with light olefins, producing ethyl benzene and cumene. Coker off-gas has a lower olefin content than FCC off- gas but still has a significant amount of C₂+ material that can be recovered. It is not uncommon that coker off-gas is combined with FCC off-gas and fed to a cryogenic unit (as previously described). For small refineries, the previously mentioned options may not be economical. In this case, they may focus on recovering the C₃+ material in the off- gas by improving the efficiency of their gas plant. Changes in unit configuration, adding chilling cooling to absorbent naphtha, and other changes can reduce C₃+ in the off-gas by more than 2-3 mol% while increasing C₃/C₄ stream flow rate by 5% or more. Q What optimal hydrocracking catalysts and operating strategies are needed to co-hydroprocess waste oils with VGO? A Andrew Layton, Principal Consultant, KBC, Andrew. layton@kbc.global There are several steps involved in co-processing waste oils. The levels of sulphur aromatics and N2 are exception - ally low, but fatty acids – unsats/oxygenates and pour point – are high. When the feed boils in the kero/diesel range at 5-10% in total reactor feed, the considerations for process - ing are less severe than when processing 100% waste oils. However, considerations apart from catalysts include:  Feed quality/storage • Flowability at temperature. Waste oils have a flowability problem at ambient temperatures • Contaminant removal/metals content. Feed contamina - tion removal from solids to metals occurs at several distinct levels dependent on the upstream pretreatment of the pur - chased feedstock. v Concentration of the waste oil in total feed • Impacts materials; reactor heat rise control; corrosion con - trol; metals build-up • Typically, around 5-10% maximum on an existing unit. w Number of reactors; beds available; heat rise control. This may not be a major issue at low concentrations, especially in VGO service. x Product quality target • O₂; olefins removal; cloud reduction y COx control (as discussed in the following). The question targets co-processing with VGO rather than diesel. Thus, cloud and flowability control may not be a main concern when sending it to an FCC or VGO hydrocracker.

Conventional Max GLN FCC High severity FCC Conventional Max C = FCC

Propylene, wt%

Figure 1 FCC operations at three different modes

PTQ Q3 2023

www.digitalrefining.com

Reactor internals Improved flow distribution technologies continue being developed to improve distribution of the feed and recycle gas. These advanced technologies prevent hot spots from developing and help quench distribution. Certain techniques are also available to ensure distribution trays function optimally. Additionally, thermowell design and reactor loading internal design help maintain sufficient flow distribution. It is also important to design the thermocouple location to best monitor temperature excursions or hot spots. Reactor bed condition To improve catalyst flow distribu - tion and minimise associated delta P (ΔP), it is important to practise proper catalyst loading and monitoring techniques. The reactor top bed catalyst and intergrading materials and design play a vital role in maintaining distribution and miti- gating ΔP. Additionally, the design of dense loading machin - ery continues to improve. Note that the skill of the loading technician is still very important. Filtration It is important to filter and treat the feed to prevent fouling in the bed, which can lead to hot spots. Knowing the fouling type and size helps filter selection. Procedures and training Both standard and emergency operating procedures can be improved to prevent and miti- gate temperature excursions: • Standard procedures should be followed during start-up, which may include adding amine or ammonia to control excursions, especially if feed or recycle flow is low on sulphur or catalyst activity is extremely high • Emergency procedures and feed type, such as loss of recy- cle gas flow, determines whether feed is, or is not, removed in addition to depressurisation • Training operators on how all processes operate and how hot spots can develop • HAZOP/MOC reviews should be conducted when chang- ing catalysts. Some companies conduct exotherm speed potential tests to compare base catalysts against new cata- lysts with higher activity. Control Several control systems can be used to help pre- vent and reduce temperature fluctuations. These controls include: • Thermocouple monitoring can track maximum tempera- ture, rate of temperature change above a certain point, radial temperature distribution, or shell temperatures. Alarms or even emergency depressurisation can be linked to these measurements • Hydrocracking catalyst may have a few separate beds to control heat rise in one bed to mitigate heat rise before the next quench point. Note that in case of an excursion, gas quench is usually inadequate to control the heat rise and, therefore, controlled depressurisation is the better approach • Temperature monitoring instrumentation can also trigger emergency depressurisation. A Fu-Ming Lee, fmlee1227@gmail.com and Maw-Tien Lee, Senior Consultants, Shin-Chuang Technology Corp., Ltd, and Ricky Hsu, Founder, ricky_hsu@msn.com, International Innotech, Inc One of the most common problems with hydrocrack- ing reactor runaway is the sudden reactor pressure rise. Hydrocracking feeds contain different sizes of solid particles

Although very waxy, VGO from waste oil is unlikely to be used for lubes production without new testing. The key cata- lyst issues are discussed as follows: • Some residual metals, notably phosphorus, will be present and must be considered when setting up any special metal trap catalyst at the top of the reactor system • The feed contains oxygenates that will generate COx. At higher temperatures, CO formation will increase, which may impact catalyst activity. Nickel Molybdenum (Ni/Mo) catalyst is less sensitive and should be the preferred catalyst. The pres- ence of a recycle gas amine contactor can help control COx, but it is essential to check its impact on the amine system • Heat rise will increase in the earlier beds, so monitoring the impact on temperature control is important • When VGO service is moving towards an FCC, further treatment consideration may be unnecessary. However, if the feed is going to a diesel product, there might be a need to add a dewaxing zeolite catalyst in a lower bed. For 100% waste oil in diesel/kero service, a second reactor for dewax- ing is typically necessary. Q With global hydrocracking unit capacity and feedstock diversity increasing, what strategies are available to pre- vent reactor runaway and increase overall unit safety? A Jay Parekh, Manager, Technology, Subject Matter Expert, Hydrocracking, ART As refiners look for more opportunities to improve profit - ability and gross margin, feedstocks that are more refractory with higher aromaticity are processed in hydrocracking units to produce high-quality liquid fuels. The more difficult feed - stock adds additional risk to refiners as the temperature exo - therms in normal operation increase and requires additional quench between beds for reactor controllability. Most modern hydrocracking units now have an auto- depressuring system (ADS), which will automatically trigger in the event of a major temperature excursion and bring the unit to a safe condition. The ADS will activate when specific reactor bed or reactor outlet temperatures exceed preset limits or when the recycle compressor fails. Loss of recycle flow is the leading cause of runaway incidents. ADS should also ensure that the reactor feed furnace burners have been tripped and the make-up hydrogen flow is reduced. While the ADS provides a safeguard to avoid a catastrophic event, it is imperative for refiners with hydrocracking units to properly train operators to follow good operating practices and be able to institute emergency procedures quickly. The hydrocracking unit should always be in a posture where reactor heat can be rapidly removed from the unit (cut fur- nace fires) while ensuring adequate compressor capacity to provide additional emergency quench gas capability to cool reactor beds quickly. A Andrew Layton, Principal Consultant, KBC, Andrew. layton@kbc.global, Dave Loubser, Senior Staff Consultant, KBC There are various contributors that can generate a heat rise or even runaway. The following are several mitigations to address potential runaway situations:

PTQ Q3 2023

www.digitalrefining.com

A long history of looking

For nearly a century, Grace catalysts have kept fuel and petrochemical feedstocks flowing from the industry’s largest refineries to the trucks, trains, planes, and ships that keep our world running. We are leveraging our long history of innovation in fluid catalytic cracking to develop products that enable lower carbon fuels and help meet the challenges of the energy transition.

grace.com

that can form a cake layer on top of catalyst inside the reac- tor. When that happens, the pressure inside the reactor will rise suddenly, leading to serious problems. However, the proprietary magnetically induced Universal Filter filtration system can remove all types of solid particles down to 7 nm or less with much simpler operation. This filtration system achieves a near-total prevention of solid particles in the liquid stream from entering the reactor, including FeO, FeS, Fe₂O₃, Ni, NiO, Co, and CoO. Furthermore, the need for expendable macropore filtration packings on top of the reactor and filter cartridges at the reactor feed entry is substantially eliminated, saving mate- rial and operational costs. These costs include loading/ unloading and disposal of the spendable materials. More detailed information is available in a previously published article in PTQ Q1 2023 (p87-95), ‘Universal filter for ultra- cleaning of reactor streams’. Q What heat exchanger fouling prediction frameworks do you see benefiting refinery and petrochemical operations? A Debjit Chandra, Manager, Global Technical Services (Refinery), debjit.chandra@dorfketal.com, and Ajay Kumar Gupta, General Manager Global Technical Services, ajay. gupta@dorfketal.com, Dorf Ketal Chemicals Fouling prediction framework for heat exchangers in refin - ery and petrochemical plants can be best achieved with the integration of analytical, statistical, and AI-based predictive algorithm approaches:  Analytical approaches can include the primary foul- ing precursors in the feed stream to the exchanger and deposit sample analysis. Screening the correct antifoulant and adjusting the chemical dosage based on key feed qual- ity variables and fouling precursors can significantly help in fouling management. v For fouling prediction on crude, changes in current feed with respect to baseline saturates, asphaltene, resin, and aromatics content/ratio can help gauge the potential fouling rate. Dorf Ketal uses the proprietary ‘Oil compatibility model (OCM)’ software to predict the stability of the crude blends. w For relative cleaning effectiveness, baseline fouling rate data analysis using good simulation software or statistical tools such as multiple variable regression analysis of previ- ous runs can help to understand the performance deviation. x Analysis of actual heat transfer rate, fouling factor and overall heat transfer coefficient (U d ), viscosity, and fluid velocity within the exchangers can help in understanding the fouling control before and after cleaning. y AI-based models can help identify key operating vari- ables, which are mainly impacting on fouling rate/run length of the exchanger performance. Modulating these variables based on AI model output has helped refiners to maximise the heat transfer rate/yield improvement. A Tina Owodunni, Senior Staff Consultant, tina.owo- dunni@kbc.global, Simon Calverley, Head of Coaching and Capability Development, KBC Heat exchanger fouling can significantly limit operations. It reduces the rate of heat transfer in the preheat train, which

increases furnace duty and sometimes reduces through- put to meet desired product purity. As a result, it increases operating costs and, most likely, increases CO₂ emissions. Additionally, as the fouling layer reduces the tube inlet diameter and the tube pitch, pressure drop increases and can cause bottlenecks in the feed pump. More severe foul- ing can force the plant to shut down. Therefore, any refinery or petrochemical plant needs an effective tool to manage fouling. While fouling is not measured, it can be calculated from kinetics, such as that introduced by Ebert and Panchal in 1997. However, the activation energy and other parameters must be determined for each crude type, which may be dif- ficult to obtain. Moreover, fouling kinetics is mostly applied to chemical reaction fouling, such as coking. It cannot be used to determine deposition fouling, so kinetic modelling is unlikely to give the complete answer. The most practical way of calculating fouling involves comparing experimental data to rigorous exchanger modelling. Rigorous models are available to understand not only the performance of shell and tube exchangers, commonly used in refineries and petrochemical complexes but also other exchangers such as plate heat exchangers. These models calculate the exchanger’s overall heat transfer coefficient when the exchanger is clean (U clean ), and performance is optimised to predict the outlet temperatures. The operat- ing heat transfer coefficient of the exchanger (U actual ) can be calculated from the plant data (such as inlet and outlet temperatures, flow rates, and composition). For a fouling exchanger, U actual will be lower, so its difference, when com- pared to U clean , determines the exchanger’s fouling factor. The complexity of these calculations is compounded because plant data often contain errors. Before calculating fouling factors, data reconciliation covering the whole heat exchanger train is needed to fit the measured data to the geometry model to find and correct errors. As a result, foul - ing calculations become convoluted. Several tools monitor fouling to manage these complexities, such as KBC’s HX Monitor, HTRI’s SmartPM, to name a few. Using a rigorous data reconciliation package, HX Monitor calculates fouling factors, runs cleaning cases, and estimates the benefits of cleaning exchanges. Then, fouling trends calculated for multiple datasets can be used to predict future fouling. A Veerala Hari Krishna, Senior Data Scientist, L & T Technology Services Ltd, veeralahari.krishna@ltts.com In refinery and petrochemical operations, one of the major problems is heat exchanger fouling, causing loss of revenue in terms of equipment replacement cost, maintenance, and cleaning expenses. Moreover, fouling is responsible for productivity losses. Heat exchanger fouling also leads to a reduction of input feed rates to the plant. Heat transfer resistance increases due to increased fouling thickness, which continuously lowers the heat exchanger operating heat duty. This predicates the need for monitoring heat exchanger fouling and forecast cleaning. Heat exchanger operations are monitored only for the rate of heat transfer. Furthermore, the heat transfer rate can be controlled by altering flow rates. An experienced process

PTQ Q3 2023

www.digitalrefining.com

CHEVRON LUMMUS GLOBAL

FUELING SUSTAINABILITY

BIOFUELS ISOCONVERSION For processing challenging feedstocks into renewable fuel products

ISOTERRA All-hydroprocessing route for maximizing yields of ASTM- approved renewable diesel or sustainable aviation fuel (SAF)

PYOIL ISOCONVERSION Waste plastics pyrolysis and circular technologies

CLG’s renewable technology portfolio is powered by cutting-edge catalysts that enable refineries to achieve higher yields of renewable fuels, base oils and petrochemicals from various low-carbon-intensity feedstocks with less waste and reduced energy consumption, allowing them to meet an evolving demand for lower carbon solutions and products. Learn more by visiting chevronlummus.com

operator can see when a heat exchanger no longer trans- fers its typical thermal output under certain flow conditions. In such cases, the operator has three options available to handle the situation: increasing the flow rate to increase the thermal output, reducing the flow rate to achieve the required outlet temperatures of the fluids, or doing nothing. In the first alternative, the heat transfer rate of the heat exchanger can be raised to its former level, but the outlet temperatures of the fluids do not attain their former levels. In the second alternative, the outlet temperatures of the flu - ids can be returned to approximately the starting position at the expense of the fluid flow rates, which may slow down production. In the third alternative, both the outlet tem - peratures of the fluids and the heat transfer rate are driven further away from their original operating points. It is clear, nevertheless, that in such a situation, the heat exchanger’s performance has deteriorated, and the previous operating level is no longer possible. Many parameters vary greatly depending on fluid flow rates. For the parameters to be comparable, they must, therefore, be proportioned to the prevailing flow conditions. Appropriate efficiency monitoring methods are limited by the available process measurements. However, diverse analyses can also be conducted with very few measurements. The efficiency of a heat exchanger can be examined, inter alia, with the help of the following measurements shown in Case 1 and Case 2 .

• Expert systems software programs that use knowledge- based rules to predict fouling rates based on input variables such as fluid properties and operating conditions. Expert sys - tems can incorporate knowledge from experienced operators and engineers to provide accurate predictions of fouling rates in heat exchangers. Overall, a combination of these frameworks can be used to provide accurate and reliable predictions of fouling rates in heat exchangers in refinery and petrochemical operations. Q To what extent do you see the expansion of digitalisa- tion for improving regulatory compliance, equipment reli- ability and operability, and reduced maintenance costs? A Philippe Mège, philippe.mege@axens.net, Marie Duverne, marie.duverne@axens.net, and Pierre-Yves Le Goff, pierre-yves.le-goff@axens.net, Axens Digitalisation of process operations has developed thanks to data transfer technologies, sensors and soft sensors gen- erating data, and IA, especially with machine learning tools, building systems that learn from data. This leverages process expertise, resulting in digital twins designed to optimise asset operation, thus securing the business decision. That ensures reliable operation and allows us to anticipate maintenance, which reduces its cost, and compare actual performances vs forecasted ones. This applies to catalysts and also equipment like heaters, compressors, and heat exchangers. Such tools are available in the Axens Connect’In digital application. Several machine learning tools have already been developed and used by operators for octane prediction, recycle gas purity estima- tion, heat exchanger network optimisation, or generating soft sensors to get streams analysis not directly measured. A Richard Evans, Head of Solutions and Innovation, Delaware UK, richard.evans@delaware.co.uk Digitalisation works on so many levels within the oil and gas sector. For example, it makes it much easier to create a uni - fied experience among employees, which helps to secure the right people with the appropriate qualifications and experience to implement work. This means it is a lot easier to remain compliant with safety regulations, for example. On another front, technology like digital twins has also matured and is now very accurate and reflective of the operating environment. This technology means planners can remain onshore, therefore reducing the risk of accidents while also saving carbon on unnecessary helicopter flights to rigs. More recent developments have been around AI and IoT and the collection and analysis of time-series data. These data first have to be normalised and tagged – does the source represent pressure, temperature or even acoustic sound- waves? But once collected, the data must be used, and this is where intelligence is applied. The data need to be referenced against example datasets to be able to spot anomalous sig- nals. An AI model can be trained to spot irregularities and build a picture of what is really happening. Whether there is excess wear in a pipe or gas is not being sufficiently heated, the AI will be able to accurately discover this and suggest preventative maintenance. It is a very granular approach that

Case 1: Temperature tags available

Sr. No.

Sensors

1 2 3 4 5

Feed temperature in Feed temperature out

Cooling medium temperature in Cooling medium temperature out

Feed flow rate

Case 2: Pressure tags available

Sr. No.

Sensors

1 2 3

Feed pressure in Feed pressure out

feed flow rate (good to have)

Some heat exchanger fouling prediction frameworks that can benefit refinery and petrochemical operations include: • Empirical correlation equations derived from experimen- tal data that can be used to estimate fouling rates based on operating conditions. These correlations are often based on heat transfer coefficients and can be used to estimate foul - ing rates in a variety of heat exchanger types • Fouling indices metrics that can be used to quantify the tendency of fluids to foul heat exchangers. These indices are based on fluid properties such as viscosity, density, and thermal conductivity, and can be used to estimate fouling rates based on fluid composition and operating conditions • Artificial neural network (ANN) machine learning algo - rithms that can be used to predict fouling rates in heat exchangers. ANNs can learn from historical data to identify patterns and predict future fouling rates based on input vari- ables, such as temperature, flow rate, and fluid properties

PTQ Q3 2023

www.digitalrefining.com

can diagnose and isolate root causes. Utilising AI means identifying the faulty piece of equipment or process the first time, thereby reducing long hours spent investigating poten- tial causes. This in itself helps to reduce overall maintenance costs and increase reliability. When real-time data are available that present how the operating environment is performing in the moment, and the design limits and regulatory requirements are embedded into the system, it is possible to make the operating environ- ment much safer, ensure that hydrocarbons stay in the pipes, and also prevent accidents. Q What are some of the most effective compressor per- formance strategies for improving the mean time between failure (MTBF)? On the other hand, a case study for a plant capacity expansion can be developed without any information about the hydraulic capacities of the existing columns. The case study that will be discussed in Part II of this article is based on the premise that a bottleneck exists at some point in the existing distillation train (or, more likely, throughout the entire distillation train) and that PPD can be employed to increase the throughput at the bottleneck. In the selected case study, the entire distillation train is debottlenecked using PPD concepts to demonstrate how PPD is imple- mented in large throughput expansions. Large and small throughput expansions A Bishwanath Mondal, Manager Global Technical Services (Petrochemicals), bishwanath.mondal@dorfketal.com, and Joice Boll, Global Technical Lead, Petrochemicals, joice@dorfketal.com, Dorf Ketal Chemicals: Changes in feedstock quality, the introduction of side streams, and increases in compressor temperature and residence time are usual factors that can affect compressor performance by increasing the fouling tendency. Some strat- egies that can be adopted to reduce the impact on compres- sor performance and run length are listed as follows: • Maintain discharge temperature towards the lower side (<90°C for CGC) and injection of wash water (BFW) as required In the upcoming Part II of this article, the development of a case study with process simulations will be presented to show the benefits obtained from debottlenecking distil - lation trains using PPD. The case study will examine the debottlenecking of the product recovery section of an ethyl- ene oligomerisation plant. A description of how the design basis and operating conditions for the process simulations were developed will be provided. Part II will provide the reader with approximate levels of ‘small’ and ‘large’ throughput expansions (expressed columns in applications involving reactor product yield dis- tribution shifts. However, it is not a straightforward task to create a design basis for a case study when applying PPD in product yield distribution shifts without knowing the hydraulic capacity limits of each of the existing columns in the product recovery distillation train.

• Use a good-quality wash oil (>85% or >90% of aromatic content) • Ensure there is no corrosion and free form of iron, as it acts as catalyst to promote free-radical polymerisation • Use efficient antifoulant to reduce free-radical polymer for - mation and polymer deposition. Dorf Ketal offers different chemical strategies depending on the compressor character- istics and plant conditions • During periods of low feed flow rate, improve wash oil and antifoulant strategies to minimise the impact of increased residence time • An effective and real-time monitoring tool can help detect early signs of problems while taking a proactive approach. The following advanced monitoring systems are currently used by Dorf Ketal: u Real-time modelling of CGC (by COMPASS) that simu- late the machine’s actual performance digitally compared to ideal conditions. Eliminate all chances of error by considering injection of wash water and other parameters of feed gas composition. COMPASS can detect early signs of fouling and suggest corrective action, which can also help in optimising wash oil and chemical consumption v Fouling Assessment Tool (FAT) is another real-time online monitoring tool that can measure the quantity of foulant and help in collecting a foulant sample online for lab studies and evaluations. Besides traditional monitoring of compressors, the above strategies, along with an efficient antifoulant treatment, have successfully enhanced machine run length in many cases. David Kockler is a Principal at Dividing Wall Distillation and Separa- tions Consulting, LLC. He specialises in the development and imple- mentation of advanced distillation processes for the chemicals and refining industries. He has over 30 years’ process design experience working in the chemicals and refining sectors and holds a bachelor’s degree in chemical engineering from Northwestern University and a master’s degree in chemical engineering from the University of Vir- ginia. Email: dwc-separations-consulting@outlook.com as a percentage of existing capacity) that are obtainable through implementation of PPD. The number of new dis- tillation columns required for large throughput expansions will be discussed (earlier in this article, it was noted that many small throughput expansions can be achieved with the addition of a single new column). A comparison of the energy efficiency of a PPD scheme versus a parallel distilla - tion train configuration will also be provided. References 1 Lappin, G. R., Sauer, J. D., editors, Alpha Olefins Applications Hand - book , 1st ed, CRC Press, 1989. 2 Lappin, G. R., et al ., Olefins, Higher, Kirk and Othmer Encyclopedia of Chemical Technology , 3 (17), 716-721, 1983, Wiley, New York, US. 3 Petlyuk, F. B., Platonov V. M., Slavinskij D. M., Thermodynamically Optimal Method for Separating Multicomponent Mixtures, Int. Chem. Eng. 5(3), 555-561, 1965. 4 Lorenz, H. M., Staak, D., Grutzner, T., Repke, J. U., Divided Wall Col- umns: Usefulness and Challenges, Chemical Engineering Transactions, 69, 229-234, 2018.

MERYT Catalysts & Innovation Your global supplier of catalysts, adsorbents and additives focused on new technologies and sustainable processes.

Improve the profitability of your processes with MERYT catalysts and our outstanding technical knowledge, experience, and excellent service Face the Energy Transition with MERYT as your best partner to achieve your objectives Reduce your energy consumption and your emissions with MERYT Catalysts and Technologies

info@meryt-chemical.com www.meryt-chemical.com

+34 868 086 998 +34 670 518 438

MERYT Catalysts & Innovation c/Berlín Parcela 3F Polígono Industrial Cabezo Beaza 30353-Cartagena Murcia SPAIN

53 11

PTQ Q2 2023 PTQ Q3 2023

www.digitalrefining.com

Vacuum tower cutpoint delivers profits

Cutpoint Concerns

poorly designed heaters may experience coking with COT below 700°F (370°C).

Crude unit vacuum tower performance is often critical to a refiner’s bottom line. e vacuum tower bottoms stream is valued far below the gas oil cuts, so most refineries look to minimize it. Many vacuum columns are also designed or revamped to produce a diesel cut, recovering diesel slipped from the atmospheric column that would otherwise be downgraded to VGO product. Good vacuum column performance can maximize the profitability of downstream units by removing distillate hydrotreater feed (diesel) from FCCU or hydrocracker feed (VGO) and removing VGO from coker feed (resid). One important measure of vacuum column performance is VGO/resid cutpoint. e cutpoint is the temperature on the crude TBP curve that corresponds to the vacuum tower resid yield. Vacuum column cutpoint depends on three variables: 1. Flash zone temperature 2. Flash zone pressure 3. Stripping section performance (if present) Flash zone temperature is driven by vacuum heater coil outlet temperature (COT). Increasing COT increases cutpoint. Vacuum heater outlet temperature is typically maximized against firing or coking limits. When processing relatively stable crudes, vacuum heaters with better designs and optimized coil steam can avoid coking even at very high COT (800°F+, 425°C), but

Flash zone pressure is set by vacuum system performance and column pressure drop. Lower flash zone pressure increases cutpoint until the tower shell C-factor limit is reached, at which point the packed beds begin to flood. Vacuum producing systems are mysterious to many in the industry, so a large number of refiners unnecessarily accept poor vacuum system performance. With technical understanding and a good field survey, the root causes of high tower operating pressure can be identified and remedied. In columns with stripping trays, stripping steam rate and tray performance are important. Stripping steam rate is limited by vacuum column diameter (C-factor) and vacuum system capacity. Any steam injected into the bottom of the tower will act as load to the vacuum system, so vacuum system size, tower operating pressure, and stripping steam rate must be optimized together. Depending on the design, a stripping section with 6 stripping trays can provide between zero and two theoretical stages of fractionation, which can drive a big improvement in VGO yield. Although the variables for maximizing vacuum tower cutpoint are simple, manipulating them to maximize cutpoint without sacrificing unit reliability is not. Contact Process Consulting Services, Inc. to learn how to maximize the performance of your vacuum unit.

3400 Bissonnet St. Suite 130 Houston, TX 77005, USA

+1 (713) 665-7046 info@revamps.com www.revamps.com

Improve energy efficiency of your hydrocracking unit

Reduced fuel firing in HCU product fractionators enables higher diesel yields and improved product properties while reducing Scope 1 and 2 emissions

Kiran Ladkat, Jan De Ren and Kiran Kashibhatla Honeywell UOP

R efinery Scope 1 and 2 emissions represent 3% of the global anthropogenic CO₂ emissions, which equates to 1,124 million tonnes annually.1 For a typical refin - ery configuration that has hydrocracking and delayed coking units, 9%² of these emissions originate from hydroprocess - ing units, where the major contributor for an individual unit is the hydrocracking unit (HCU) because of the higher operat - ing severity as compared to hydrotreating units. Figure 1 provides an overview of the three GHG protocol scopes (1, 2, and 3) and categories for each of the scope emissions. Improving energy efficiency and reducing CO₂ emissions from existing HCUs is a key focus area for improv - ing refinery profitability and reducing emissions. Within the HCU, the main contributors to carbon emissions are fired heaters and rotating equipment. Against this backdrop, Honeywell UOP’s dual stripper and dual fractionator solutions for HCUs have demonstrated

reduced fuel firing in the product fractionator feed heater by ~50-55%, enabling higher diesel yield and improved diesel product properties. Together, this delivers improved refinery economics and reduced Scope 1 and 2 emissions. These are solutions that can be applied to new and existing HCUs. The fractionation section of an HCU is designed to sep - arate the net reactor effluent from the reactor section into the desired products: LPG, naphtha, kerosene, diesel, and unconverted oil. A simplified flow diagram of a single strip - per first HCU fractionation section is shown in Figure 2 . The fractionation section typically includes a stripper, a product fractionator with two or more side cuts, side-cut strippers, a debutaniser, a naphtha splitter, and other columns, depend - ing on the required product recovery. Dual stripper flow scheme for existing HCUs Several new HCUs have been designed by Honeywell UOP

HFCs

PFCs

Scope 2 Indirect

Scope 1 Direct

Scope 3 Indirect

Transportation and distribution

Purchased goods and services

Purchased electricity, steam, heating & cooling for own use

Investments

Capital goods

Leased assets

Company facilities

Processing of sold products

Fuel and energy related activities

Employee commuting

Franchises

Company vehicles

Transportation and distribution

Use of sold products

Business travel

Leased assets

Waste generated in operations

End of life treatment of sold products

Reporting company

Upstream activities

Downstream activities

Figure 1 Overview of greenhouse gases (GHG) protocol scopes and emissions across the value chain³

PTQ Q3 2023

www.digitalrefining.com

O - gas

Unstabilised naphtha

Naphtha

Stripper

Kerosene

Product fractionator

Cold ash drum liquid

MP steam

Diesel

Hot flash drum liquid

Product fractionator feed heater

LP steam

Unconverted oil

Figure 2 Process flow scheme for single stripper first fractionation section of an HCU

passing through the product fractionator feed heater, thereby avoiding a mixing of the hot and cold flash drum liquid. This has the potential to save on fired duty, thus making the HCU more energy efficient while reducing carbon emissions. In the dual stripper design, the hot and cold flash drum liquid streams from the reactor section are fed into separate strippers: a hot stripper and a cold stripper. Both columns are steam stripped. The overhead vapour from the hot strip- per is routed to the cold stripper, whereas the liquid from the hot stripper is sent to the product fractionator feed heater and subsequently to the flash zone of product fractionator. In this arrangement, only liquid from the hot stripper bottom is being sent to a product fractionator feed heater, unlike in a single stripper arrangement where all the liquid is sent to the product fractionator feed heater, thereby demanding higher energy input and creating higher resultant flue gas emissions. The cold stripper bottoms liquid is preheated with availa- ble process heat in the fractionation section to reach a certain Figure 3 Shandong Super Energy two-stage HCU in China employing the dual stripper flow scheme

with the dual stripper flow scheme and put into operation, making this a commercially proven solution (see Figure 3 ). By implementing this flow scheme, refiners will be able to reduce the product fractionator feed heater duty by 20-40% compared to a conventional single stripper flow scheme, depending upon HCU conversion. Apart from new HCUs, the dual stripper flow scheme provides an excellent revamp solution to reduce energy con- sumption in an existing HCU. The novel flow scheme (see Figure 4 ) was developed to reduce product fractionator feed heater duty and deliver a reduction in operating costs and furnace stack emissions. For reactor section flow schemes incorporating a hot separator, it is noted that the composi- tion of the cold separator hydrocarbon stream, and therefore the cold flash drum hydrocarbon stream, is much lighter than that of the hot flash drum liquid. This makes it possible to heat the cold flash drum hydrocarbon stream using low-end process heat, available in the fractionation section, without

O gas

O - gas

Debutaniser

Unstabilised naphtha

Naphtha

LPG

Cold stripper

Product fractionator

Kerosene

Product fractionator

Kerosene

Cold ash drum liquid

MP steam

Debutaniser reboiler

Cold ash drum liquid

Diesel

Hot stripper

Hot ash drum liquid

MP steam

Product fractionator feed heater

LP steam

Unconverted oil

Product fractionator feed heater

New / modications

Figure 4 Revamp process flow scheme with dual stripper fractionation section of an HCU

Figure 5 Process flow scheme with the debutaniser-first fractionation section of an HCU

PTQ Q3 2023

www.digitalrefining.com

Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32 Page 33 Page 34 Page 35 Page 36 Page 37 Page 38 Page 39 Page 40 Page 41 Page 42 Page 43 Page 44 Page 45 Page 46 Page 47 Page 48 Page 49 Page 50 Page 51 Page 52 Page 53 Page 54 Page 55 Page 56 Page 57 Page 58 Page 59 Page 60 Page 61 Page 62 Page 63 Page 64 Page 65 Page 66 Page 67 Page 68 Page 69 Page 70 Page 71 Page 72 Page 73 Page 74 Page 75 Page 76 Page 77 Page 78 Page 79 Page 80 Page 81 Page 82 Page 83 Page 84 Page 85 Page 86 Page 87 Page 88 Page 89 Page 90 Page 91 Page 92 Page 93 Page 94 Page 95 Page 96 Page 97 Page 98 Page 99 Page 100 Page 101 Page 102 Page 103 Page 104 Page 105 Page 106 Page 107 Page 108 Page 109 Page 110