Armand Abay, Sean Sears and William F. Johns, Refined Technologies, Inc., USA, EXP XP ES R S ES ENTR NTR Methods of purging and cooling high

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1 Armand Abay, Sean Sears and William F. Johns, Refined Technologies, Inc., USA, discuss how the safe entry of reactor high pressure loop systems in hydrotreaters and hydrocrackers can be expedited by the application of patented chemistry and procedural changes during critical steps in the shutdown process. EXPRESS D ENTRY emand, via new regulations, for high value and environmentally clean petroleum products has become more prevalent in recent decades. Sulfur content restrictions continue to tighten. Hydrotreating and hydrocracking processes have evolved in the industry as the premier processes for producing clean, high value products. Equally important is to produce these products while employing safe operating procedures. Refineries and chemical plants perform periodic turnarounds on hydrotreating and hydrocracking units, typically to skim or fully change out spent catalyst. Due to the high surface area of the catalyst filled reactors, the owners face a common challenge related to purging until the level of hydrocarbons, H2S and hydrogen is below the lower explosive limit (LEL) upon opening the reactor system. Delays are very common. These shutdowns, while necessary to continue to operate the units efficiently, require time consuming procedures that can cost the site millions of dollars in reduced daily production. Reducing shutdown duration while quickly and safely performing the work is a strategic advantage in today s operating environment. Methods of purging and cooling high pressure reactor loops Accepted standard methods for preparing hydroprocessing reactor high pressure loops for safe work involve a hot hydrogen strip, where a furnace in the reactor loop is used to raise the hydrogen stream temperature levels to a point where it facilitates the removal of heavy hydrocarbons, light ends and noxious gases from the catalyst, after the feed has been removed from the unit. Subsequently, the unit is cooled by continual circulation of the cooled gas stream through the

2 Figure 1. Simple, single reactor system. Figure 2. Complex, multiple reactor system. reactor system. Once the system has met temperature requirements, the hydrogen is replaced with nitrogen by repeatedly depressurising the reactor loop to the flare system and re-pressuring it with nitrogen (commonly called a huff and puff ). These processes typically require large quantities of costly nitrogen and result in long periods of flaring. The goal of these legacy procedures is to provide the loop clean of residual hydrocarbons for maintenance work and safe reactor entry (<10% LEL, 0 ppm H 2 S, 0 ppm benzene and <100 F temperature of the reactor[s] beds). Depending on the size and state of the unit, the entire effort typically takes four days or longer. In summary, typical legacy procedures in today s environment are time consuming, expensive and result in significant loss of products. Furthermore, improperly cleaned catalyst introduces safety risks and extends labour expenses for unloading the spent catalyst. Refined Technologies, Inc. (RTI) has developed and implemented a patented process, which significantly shortens shutdown timelines by eliminating the hot hydrogen strip step, reduces nitrogen expenses, reduces flaring, and lowers maintenance costs for hydroprocessing and other catalytic refinery units. Solvent technology Historical hot hydrogen strip methods rely on the temperature and mechanical sweeping effect of a hot gas strip to remove the residual heavy and light end hydrocarbon from the catalyst. This method is unpredictable, so owners typically extend these strip steps to commonly a shift or more. Even after this extended hot strip, owners frequently experience residual oil on their catalyst and unacceptable LEL readings when opening the reactor system post cooldown. Recent technology advances focus on adding a fully organic solvent to the sweep gas during the shutdown of a hydroprocessing or reforming unit. The vapourised chemical thins out heavy hydrocarbons, allowing for their removal from the catalyst surface and faster evaporation of light hydrocarbons. The solvency strength (measured by KB value) of the chemical also aids the sweep gas in the removal of H 2 S, benzene, etc. The chemistry is injected into the hydrogen gas stream ahead of the feed/effluent exchangers or ahead of the reactor. The reactor effluent is cooled and the displaced hydrocarbons are either condensed in cold separators or purged from the unit as gases. Upon completion of the chemical injection, the cooldown process continues. The hot hydrogen strip is eliminated. First North American trial cleaning using natural gas In January 2009, a novel application was executed on a naphtha hydrotreater (NHT) in the Canadian oilsands. The company had traditionally used long periods of hot stripping on the front end of the shutdown and prolonged cycles of pressuring up and dumping with nitrogen on the back end of the shutdown, attempting to achieve acceptable LEL readings for entry into the reactor. Even after 36 hours of hot hydrogen stripping and 17 hours of pressuring up and dumping with nitrogen, the reactor outlet tested at 18% LEL upon opening. During the first trial application, after hot stripping, the company used natural gas to cool the reactor. The novel solvent was injected into the natural gas, which allowed for quick removal of hydrocarbons from the entire high pressure loop. Once cool, the company began pressuring up and dumping the reactor system with nitrogen. After nine hours of pressuring and dumping, gas testing at the reactor outlet indicated 0% LEL. Entry into the reactor was achieved with nearly half as many pressure/dumps and the LEL reading of 0% was previously thought to be unachievable. Due to the savings in time, nitrogen consumption, and much Reprinted from September 2016 HYDROCARBON ENGINEERING

3 safer LEL level, the company decided to use the solvent on future NHT shutdowns. Subsequently, it has dramatically reduced hot stripping on the front end of the shutdown, saving even more time and allowing even faster entry into the reactor. Figure 1 illustrates the high pressure loop of a typical single reactor naphtha hydrotreater. The solvent is injected into the recycle gas stream at the feed/effluent exchanger and feed heater. The entire loop is left gas free and all hydrocarbons are removed from the reactor through the two injection points. Second trial injection using hydrogen In October 2009, the technology (QuikTurnRX ) was implemented on a large US hydrocracker. In contrast to the first application, which used natural gas as the circulating gas, the chemical injection took place in a circulating hydrogen stream during the unit cooldown process (Figure 2). Multiple injection points were used in this application to accommodate the three large reactors and feed/effluent exchangers. This two stage hydrocracker historically had high LEL readings when testing the reactors upon completion of the traditional hot strip and cooldown process. Application of the technology resulted in LEL levels below 3% in record time. As a point of interest, catalyst from the second stage reactor was reused in the first stage without any negative impact on activity. Catalyst regeneration and reuse Use of RTI s chemical and procedures has demonstrated no deleterious effects on hydrotreating or hydrocracking catalyst reuse and regeneration. Several units have been restarted after the technology application with the same catalyst in place. Furthermore, in numerous units, catalyst has been unloaded, sent off for regeneration, reloaded into the clean reactors and started up. Technical personnel at these facilities reported that unit operations after the chemical cleaning indicated no loss of catalyst activity or change in physical properties. RTI was invited to participate in a hydroprocessing pilot plant research project by a major US refiner. The purpose of the research project was to test QuikTurnRX compatibility with diesel hydrotreating catalyst. The test measured catalyst activity before and after exposure to QuikTurnRX in the presence of high purity hydrogen at 450 F and 450 psig. Even though the reactors were dosed with 20 times the normal chemical dosage compared to field applications, the catalyst showed no loss in activity. Precious metal catalyst The technology has been applied in several hydrocracker high pressure loop systems, including a lube oil hydrocracker. All of the units contained precious metal catalysts. In some cases, the application took place ahead of a catalyst skim, thus returning cracking catalyst back into service after being chemically cleaned. After startup, the catalyst exhibited no change in activity or physical properties. Another hydrocracker, after being cleaned, was mothballed for several months with cracking catalyst left in place in the reactors. When the unit was placed back in service, activity of the catalyst was unchanged. High pressure loop maintenance activities There have been a number of demonstrated, positive impacts on maintenance activities in the high pressure loop as a result of implementing the technology. Hydrocarbon free, dry catalyst flows more easily from reactors, saving time and reducing maintenance costs. Feed/effluent heat exchangers are cleaned along with the reactors, allowing for immediate maintenance work to begin on these critical pieces of equipment. Reactor internals are free of hydrocarbon and ready for inspection and repairs. Recycle gas compressors Hydroprocessing units typically use centrifugal compressors to continuously recirculate hydrogen to facilitate the catalytic process. These compressors are designed to compress clean dry gas. The chemical used in the vapour phase cleaning process is condensed in the high pressure separator prior to flowing through the compressor in the high pressure loop. The process does not impact the mechanical integrity of the process machinery. Reduction of nitrogen use Application of the technology reduces the amount of nitrogen used for the process of eliminating contaminants in the high pressure loop. The power of the chemistry to dissolve and remove hydrocarbons from the reactors leads to significantly less nitrogen required for ridding the system of troublesome light ends and H 2 S. The amount of nitrogen saved is unit specific, impacted by many variables. Savings of 2-5 trucks are very common. Units particularly difficult to clear of contaminants can expect greater nitrogen savings from historical norms. Applications The first three applications were conducted in Since then, RTI has completed >190 applications on hydrotreaters, hydrocrackers, and other catalyst packed reactor systems. Many companies have requested repeat applications based upon their initial success. The technology has been applied in a variety of circumstances: n Small, single bed hydrotreating reactors (naphtha, isooctene). n Large, multi-bed, multi-reactor distillate and heavy gas oil hydrotreaters. n Large multi-stage hydrocrackers. n Units with circulating hydrogen or natural gas. n Once through hydrogen without recycle gas compressors. n Once through hot nitrogen. n Catalytic reformers. Catalytic reformers RTI has executed projects in all three types of catalytic reformers: a semi-regeneration (SR) unit, which normally regenerates catalyst every 1-2 years, a cyclic regeneration (CR) unit with multiple reactors, one typically regenerated each day, and a continuous regeneration (CCR) unit. RTI was approached by companies to effectively remove hydrocarbons (high in benzene content) from reactor systems in preparation for the removal and reclamation of the precious metal catalyst. In the case of the SR and CR units, existing procedures called for complete catalyst regeneration involving significant downtime and nitrogen costs. In addition, the reactors were of a radial flow design with flow through scallops, which tended to retain hydrocarbons, making the reactors difficult to clear for entry. The RTI technology was applied in place of the carbon

4 Table 1a bpd HDS unit previous shutdown timeline Task Hrs Stop feed, flush and prepare for hot strip 26 Hot strip min. of 16 hours, or until no more liquid accumulation Cooling to 350 and lowering pressure to 1 psig Pressure dump and fill with N 2 and restart compressor NiCool injection until bed temperature is below 150 F and skins is below 250 F Total shutdown duration 118 Day 1 Day 2 Day 3 Day 4 Day 5 Days Nights Days Nights Days Nights Days Nights Days Nights Table 1b bpd HDS unit QuikTurnRX process actual 2013 shutdown timeline Table 1b bpd HDS unit QuikTurnRX Day process 1 actual Day shutdown Day 3 timeline Day 4 Day 5 Task Hrs DaysDay Nights 1 DaysDay Nights 2 DaysDay Nights 3 DaysDay Nights 4 DaysDay Nights 5 Task Hrs Stop feed and perform diesel flush 8 Days Nights Days Nights Days Nights Days Nights Days Nights Sweep Stop feed reactor and perform loop and diesel cooldown flush to F Sweep reactor loop and cooldown to 6 Cooldown 500 F to 450 F, pressure to 450 psig 12 and connect injection and drain piping Cooldown to 450 F, pressure to 450 psig 12 Refined and connect Technologies injection chemical and drain injection piping 4 Cooldown Refined Technologies with H 2 to >120 F chemical bed/>300 F injection 30 4 skin temperatures Cooldown with H 2 to >120 F bed/>300 F 30 Shutdown skin temperatures RGC, depressure system and 10 perform two N 2 pressure dump and fills Shutdown RGC, depressure system and 10 Shutdown perform two NiCool, N depressure system 4 2 pressure dump and fills and test LEL and H 2 S Shutdown NiCool, depressure system 4 Total and test shutdown LEL and duration H 68 2 S Total shutdown duration 68 burn and the units were quickly prepared for maintenance with complete removal of contaminants and large savings in nitrogen usage. Similar to hydroprocessing applications, the solvent was injected into the circulating hydrogen stream, condensed hydrocarbons removed in the separator and light gases purged to fuel gas or flare systems. In these cases, the RTI chemical did not interfere with the offsite precious metal reclamation process or operations after startup. Application of the technology at the CCR was designed to remove hydrocarbons from the stacked reactors, catalyst collector and hopper. Preparing this reactor system for maintenance had historically been difficult. Through use of the RTI chemical and process, objectives were achieved and the unit readied for maintenance as planned. Expediting reactor entry There are many examples of time savings (from oil out to reactor blinding) associated with the QuikTurnRX application. Every unit is different and the amount of time saved depends upon many factors, including: n The efficiency of the traditional process. n The length of time and temperature of the current hot strip. n The time required for cooling the reactor. Savings of 1-2 days in the shutdown process have been typically observed in the seven years of performing these applications. Table 1 is an example of an actual application on a large diesel hydrodesulfurisation (HDS) unit, where 50 hours were saved through the technology application. Conclusion The use of a chemical solvent in RTI's patented QuikTurnRX process has been proven to expedite entry into reactor systems since Typical hot hydrogen strip steps have been shortened or eliminated, and the need for long nitrogen purges or many huffs and puffs reduced. Entry into reactors has been achieved in record times. The technology has been successfully applied in a variety of units with no adverse impact on catalyst activity. The ability to remove hydrocarbons and others contaminants from the entire high pressure loop has sped up entry into feed/effluent piping systems and heat exchanger trains. Note This article is based on a paper that was first presented at the 2016 AFPM Annual Meeting, which took place on March in San Francisco, California. Reprinted from September 2016 HYDROCARBON ENGINEERING

5 NEW PATENT EXPEDITES REACTOR ENTRY Very little has changed in the past 50 years when it comes to purging hydrocarbons and H 2 S from calalyst-filled reactors and high pressure equipment loops. Common methods include hot H 2 stripping and long N 2 purges. Change has been long overdue for optimizing the front end of Hydrotreater, Hydrocracker and Reformer turnarounds. Let s talk soon regarding your upcoming turnarounds and catalyst skims. Patented Chemistry + Detailed Planning + Professional Execution At Refined Technologies, we apply our demonstrated knowledge of chemical cleaning, our process experience in refineries and upgraders across North America, and our proprietary chemistry in ways that improve client operating margins. Vaporganic Our Vaporganic cleaning process is a patented vapor phase application using our QuikTurnRX solvent. Shortens timeframe between oil out and reactor entry. Cleans all equipment in the high pressure loop Expedites maintenance. All projects 100% guaranteed. QuikTurnRX Chemistry Pure organic solvent (no H 2 O), residue free. Injected into dry atmospheres (H 2, N 2, natural gas). Compatible with catalyst. Use for full catalyst changes or skims. Documented Results - Over 200 Applications and Counting Reactor entries in record time, shaving 1-2 days off turnaround times. Elimination of hot hydrogen strips. Eliminates LEL and H 2 S issues. Reduction in N 2 usage. Reduces time in the flare. No environmental, effluent or safety issues. All high pressure equipment is hydrocarbon and H 2 S free. Visit or call us at Video animation: Kevin Roberts - kroberts@r-t-i.com Cody Nath - cnath@r-t-i.com

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