PTQ Q1 2025 Issue

possible to operate a hydrocracker in ‘swing mode’ where the product objectives switch between maximising middle distillates (MDs) and maximising naphtha. This requires a margin in the operating temperature of the catalyst, so it should be a medium-to-high activity hydrocracking catalyst. If the unit is operated in recycle mode, maximum (‘max’) MD is favoured, and changing to once-through operation will lead to a switch to a higher naphtha produc- tion rate. High-activity catalyst may be installed in the latter part of the hydrocracking reactor, and the temperature profile may be changed from ‘equal-outlet’ to ‘ascending’ to move more conversion to the more active catalyst with a higher naph- tha selectivity. The change in temperature profile may be amplified in case the unit has several reactors, and a heat exchanger is installed between the two last reactors so that the high-activity hydrocracking catalyst can be oper- ated colder during max MD production and hotter during maximum naphtha production campaigns. It is important to check that the fractionation section, especially the overhead section and light ends recovery sections, can handle higher amounts of light material inad- vertently being produced during maximum naphtha pro- duction if the unit normally produces max MD. It should also be checked if the unit is able to provide the necessary lift of light material during max MD production in case normal operation is max naphtha. Hydrocrackers are, in general, very flexible, and a full range of catalysts from max MD to max naphtha production may be applied with the right expertise and safety considerations. A James Esteban, James.Esteban@unicatcatalyst.com, UNICAT Catalyst Technologies, LLC, Fu-Ming Lee, fmlee@ shinchuang.com, Tzong-Bin Lin, Maw-Tien Lee, Chi-Yao Chen, Mark Zih-Yao Shen, and Ricky Hsu, Shin Chuang Technology Co., Ltd In the ever-evolving landscape of hydroprocessing, the ability to adapt operations swiftly is paramount for refiners aiming to optimise production and meet market demands. A well-designed graded bed system, particularly utilising Unicat’s Advanced Filtration System (AFS) and MagAFS technologies, is essential for enhancing the operational flexibility of hydrocrackers. These systems not only opti - mise catalyst performance but also ensure that refiners can

respond effectively to changing product requirements, such as shifting from naphtha to diesel output. The design of the catalyst bed is fundamental to the efficiency and longevity of hydrocracking operations. AFS technology provides a unique solution by offering high available void space and optimised flow channels, mitigat - ing pressure drop, which is critical in maintaining consistent reactor performance. The AFS allows for uniform distribu- tion of reactants, ensuring that the catalyst operates at peak efficiency throughout its lifecycle. Refineries utilising AFS have reported significant improvements in operational metrics. For instance, one facility experienced a 150% increase in cycle length com- pared to traditional grading systems, leading to reduced downtime and enhanced profitability. This extended cycle life translates to lower operational costs and improved throughput, allowing refiners to maximise output without compromising product quality. Hydrocracker flexibility The flexibility built into hydrocracker operations through advanced catalyst systems like AFS and MagAFS is multi- faceted. The ability to quickly adjust operational parameters allows refiners to optimise yields based on real-time market conditions. When transitioning from naphtha to diesel pro- duction, the graded bed system can accommodate changes in feed composition and processing conditions without significant downtime. In one case, a refinery successfully shifted its output from naphtha to diesel within a matter of hours, thanks to the rapid response capabilities enabled by the AFS. This adaptability not only meets immediate mar- ket demands but also positions the refinery to capitalise on price fluctuations, enhancing overall profitability. Integration of demetalisation catalysts within the AFS framework enhances the ability to process a wider range of feedstocks. By effectively removing contaminants such as metals, these catalysts prolong the life of the primary hydrocracking catalysts and facilitate smoother transitions between different product outputs. Facilities employing Unicat’s demetalisation and grading catalysts have reported a minimum of a 30% reduction in catalyst replacement frequency, significantly lowering maintenance costs and improving operational efficiency. This reduction in downtime and/or process unit utilisation is crucial for

XRF analysis showing metals removal by MagAFS filter

Element

Metal %, inlet liquid (0.5877) *

Metal %, inlet liquid (0.5877) **

% Removal by filter

26.86 wt% 9.49 wt% 843 ppm 0.43 wt% 0.53 wt% 224 ppm 1,529 ppm 1,337 ppm

12.67 wt% 14.78 wt%

98.9 96.2

100.0

Al Cr

2.16 wt% 2.14 wt%

87.6 90.0

100.0

Ni Cl

1.57 wt% 1.92 wt%

74.4 64.4

220 ppm

100.0

* Total solids in 13 litres of feed liquid to the filter (0.5877g) ** Total solids in 13 litres exit liquid from the filter (0.0144g)

Table 1

PTQ Q1 2025