Document1 21/9/2002 12:09 Page 1
QUESTIONS & ANSW
Previous successes: revamping the unit to DMHC mode
capital f one of th alysts du Nobel ar phur red abateme platinum capabilit ❝ H wo technolo molecul ing faci Goelzer: between respect t opposed sented) f few alter From plier or c lar and feeds an problem and guar Refine methods under-ac or in oil gy/catal toleranc Some for adva and mol or via m ry analy cated an For e FCC/RFC ern fluid reactor o pilot pla A num or week tion ana high tem sophistic tion and with RV for distil ucts and dard for D-1160 employe Berth for direc key m (FCC/RF diesel hydroge been slo tions an gen as k
Mbugua Gitau is Senior Technical Service Engineer – Hydroprocessing at Shell Catalysts & Technologies, where he engages with refining cus - tomers, helping to unlock potential from their hydroprocessing units with a focus on value-adding catalyst solutions. He holds a master’s degree in chemical engineering from the University of Bath, UK. Email: mbugua.gitau@shell.com The revamp achieved a significant increase in T95 shift of 16°C, compared to the average of the origi - nal cycle when the unit was just in distillate dewaxing service. Additional benefits included a large density improvement, and therefore volume gain, and high die- sel recovery. High accessibility and accessibility retention are required the make the processing of even more contam- inated residual feedstock possible. Akzo Nobel has intro- duced the Opal, Sapphire and Coral catalysts line featuring enhanced accessibility. opening, an advanced chemical upgrading technique. Such a solution, capturing a substantial margin, does not come off the shelf. To evaluate revamping the unit into a DMHC, Tüpraş worked with Shell Catalysts & Technologies. This work included dedicated pilot plant testing and thermal stabil- ity reviews. The solution they devised was a customised catalyst system. No hardware changes were necessary. It fea- tured a latest-generation, high-activity NiMo catalyst and a zeolite cracking catalyst to crack the heavy tail. As the latter catalyst also had a tendency for dewaxing, the win- ter diesel specifications were also met. upgrading process for the oil refining industry, producing vast quantities of transportation fuels. It is also expected that it will gain importance as supplier of propylene worldwide and occasionally ethylene. The FCC process and the products it produces will have to meet strict emission standards. With respect to the processing of residual feedstock in FCC, perhaps the most important change in modern FCC catalyst design is the quantification and subsequent optimisation of catalyst accessibility. Data from about 20 commercial experiences show that when contaminants like iron, vanadium, calcium and sodium increase, cata- lyst accessibility decreases rapidly. When catalysts with high accessibility (as measured by the AAI – Akzo Acces- sibility Index) are used, very marked improvements in activity and selectivity are achieved. To enhance the production of light olefins, especially propylene, in the FCCU stable narrow pore zeolites, eg ZSM-5, are required. This has to be combined with a host FCC catalyst featuring high propensity to produce olefinic precursors, which are subsequently cracked to light olefins. Increased ability of the FCC catalysts system to make lower sulphur-containing products is necessary for an overall more profitable refining operation. Reduced NO x and SO x emissions from the FCC stack are also required. The introduction of new FCC catalyst additives as
suboptimal catalyst utilisation and poor vapour–liquid dis- tribution throughout the cracking bed, which would reduce diesel yield and threaten cycle length. Standout performance has been delivered as a result of the new reactor internals and a leading-edge catalyst system. Tüpraş reports enhanced gas–liquid distribution over the catalyst beds. With lower operating temperatures and reduced radial temperature spreads, it has been able to: • Increase throughput by 5% • Process heavier feeds • Extend the cycle length from three to four years. Crucially, increasing the cycle length has enabled the planned distillate hydroprocessing catalyst changeout to fall within a major inspection turnaround, thereby saving Tüpraş the trouble and cost of a catalyst swap outside this period. This is not the first time Tüpraş has demonstrated a will - ingness to think outside the box with this unit. Several years ago, when it was running as a high-pressure distil- late dewaxing unit, Tüpraş revamped it to run as a distil - late mild hydrocracker (DMHC) and became one of only a few refiners worldwide to benefit from this mode of operation. The objective was principally to enable the upgrading of two high-margin streams that are particu- larly challenging, namely the heavy gas oil (HGO) and light vacuum gas oil (LVGO) fractions. In distillate dewaxing service, the unit was process- ing HGO and meeting the T95 ultra-low-sulphur-diesel specification of 360°C. A DMHC can handle much greater quantities of HGO, and LVGO can also be added up to cold-flow property limits. Compared with a conventional distillate dewaxing unit, a DMHC delivers a step change in T90+ shift with benefits to density, cetane, and distil - late recovery. Cracking the heavy tail in a DMHC requires a highly customised catalyst solution that promotes ring
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Ersev Dağ is Process Control Superintendent at Tüpraş Kırıkkale Re - finery, where he is responsible for the distributed control system and advanced process control environment. He holds a bachelor’s degree in chemical engineering from Gazi University, Turkey. Elif Kızlap is Process Superintendent at Tüpraş Kırıkkale Refinery and responsible for hydroprocessing units. Her role involves increasing unit profitability, adopting new technologies and optimisation. She holds bachelor’s and master’s degrees in chemical engineering from Hacettepe University, Turkey. She has published an article in the Jour- nal of Materials Science: Materials in Medicine (2019) and authored a Turkish patent related to her master’s degree topic. Enes Cındır is Chief Process Engineer in the hydroprocessing team at Tüpraş Kırıkkale Refinery, where he is responsible for hydrocracking units, hydrogen manufacturing units, sour water stripping, and sulphur recovery units. He has operational experience in refinery operation, dis - tributed control systems, staff management, process products quality monitoring, and catalyst performance monitoring. He holds a bach- elor’s degree in chemical engineering from Ankara University, Turkey.
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