PTQ Q2 2023 Issue

Conventional tray 10 – 15% wetting

Bubble cap tray 20 – 30% wetting

Shell HD tray Near-perfect wetting

Inert material

Dry catalyst

Wet catalyst

Figure 6 Shell HD tray optimises catalyst utilisation

Figure 5 A Shell HD tray

Although the unit at Kırıkkale was designed for 4,500 m 3 /d, Tüpraş has increased that throughput by 5% to 4,725 m 3 /d. The new feed rate was sustained throughout the cycle, as seen in Figure 8 , and the Covid pandemic had minimal effect on feed rate and operations. Additionally, the new internals have improved opera- tional flexibility for both the DHP unit and the crude distil- lation unit in terms of heavy diesel distillation. With good internals, lower differential pressure was observed, which also led to reduced compressed charge gas cycling. Tüpraş views the internals changeout project as a com- plete success. A key part of this was the excellent prepa- ration and clear definition of the field operations required before the work took place. Because of this preliminary communication, Tüpraş did not encounter any unforeseen problems during the installation period. By defining the problem and quickly taking action to solve the issues, the partnership led to a successful project that improved reactor stability and safety on the site. Against a backdrop of extensive fieldwork, the project shows how excellent planning and cooperation within a trusted part- nership led to a smooth shutdown with minimal downtime. Key takeaways Thermal maldistribution was identified in the cracking bed of the DHP unit from measurements of the radial to axial DT ratio. The measured thermal maldistribution suggested

and interpretation of video footage taken during the 2015 turnaround helped them to identify flaws in the existing internals. This provided a compelling case for changing the internals at the next turnaround. In 2018, the refinery removed the existing hardware, installed Shell’s latest-gen- eration internals and optimised the catalyst system. Reactor internals from Shell Catalysts & Technologies include Shell HD trays and ultra-flat quench (UFQ) inter- bed devices. Shell HD trays (see Figures 5 and 6 ) provide high uniformity of vapour–liquid distribution, thus address- ing the issue of poor catalyst utilisation, which can lead to undesirable radial temperature maldistribution. Shell UFQ interbed internals (see Figure 7 ) achieve ultra- uniform temperature distribution in the reactor by promot- ing uniform gas–liquid quench mixing and redistribution between catalyst beds. These conditions are imperative for optimum catalyst utilisation in the bed below. The UFQ internals integrate fully with the HD trays and help to reduce the radial temperature gradient, typically by a factor of three to five, compared with a conventional mixer. Results and value added The results have been dramatic. In February 2022, at the end of a stable four-year cycle, the catalyst was changed, and operational strategy has altered such that further four- year cycles are planned for the future rather than the tradi- tional three-year cycle.

2600 3200 3000 2800 3400 3600 3800 4000 4200 4400 4600 4800 5000

4 , 725m/d max throughput

200

400

600 800 1000 1200

1400

Days on stream

Total feed volume rate per day - (m/d)

Figure 7 Shell UFQ interbed internals

Figure 8 DHP feed rate throughout the four-year cycle

PTQ Q2 2023