Catalysts, conversions and revamps

A modernisation programme at Ukraine’s largest refinery, JSC Ukrtatnafta’s facility at Kremenchug, Poltava Oblast, has enabled the corporation to meet Euro IV diesel and gasoline specifications. Significantly, this upgrade was achieved cost-effectively and well ahead of the mandate deadline.

Ukrtatnafta launched the improvement initiative in 2009 in response to stringent fuel specifications scheduled to come into force in 2011. The refiner commissioned Shell Global Solutions and its affiliated catalyst company, Criterion Catalysts & Technologies, to analyse the refinery’s business situation. Then, together, the developed customised process unit designs and catalyst systems.

First, they revamped a two-train diesel hydrotreating (DHT) unit to optimise its production capabilities. This required minimal infrastructure changes and has enabled uninterrupted production of Euro III automotive diesel (<350-ppm sulphur content). Moreover, by using a lighter feedstock, the solution enables Ukrtatnafta to meet Euro IV guidelines (<50-ppm sulphur content). Key to the solution was Criterion’s new generation of catalyst technology, ASCENT DC-2531, a high-activity cobalt–molybdenum catalyst providing a full range of sulphiding options and handling and loading flexibility.

Reactor modifications were also made: Shell Global Solutions reactor internals were introduced, including High Dispersion trays for highly uniform vapour–liquid distribution and excellent thermal distribution; filter trays to revent foulants from entering the catalyst beds;  and ultra-flat quench interbed internals for uniform process and quench mixing at the interbeds. These reactor internals can produce 30–50% activity gains through improved catalyst utilisation and extra volume for loading catalyst.

In addition, Criterion and Shell Global Solutions recommended the conversion of another DHT unit to treat straight-run vacuum gas oil. This would improve the feed to the fluidised catalytic cracking unit, which would help to enhance gasoline quality, and was a cost-effective solution because minimal changes were required.

New reactor internals were fitted, and a customised catalyst solution was devised that has extended the catalyst’s lifespan to a cycle of about 24 months to give longer intervals between scheduled maintenance. The catalyst solution uses ASCENT DC-2551 catalyst, which was specially developed for medium-pressure vacuum gas oil hydroprocessing applications and provides high coke stability, metals uptake capacity and high activity; and ASCENT DN-3551 CFH nickel–molybdenum pretreatment catalyst, which is designed to protect fluidised catalytic cracking catalysts from metal feed contaminants.

The operational changes went online mid-2009 and their bottom-line impact has been dramatic. During a 12-month period ending in mid-2010, Ukrtatnafta’s sales increased by more than 49% and its revenues by more than 129%.

Sergey Koshelyuk, Deputy Chairman of the Board, JSC Ukrtatnafta, attributes these results to the collaborative approach that was adopted. He says, “In Criterion and Shell Global Solutions, we gained trusted advisers that not only focused on the project at hand but also brought forward options and new ideas to help us reach our objectives and seize new opportunities to serve our customers better.”

He adds, “The Kremenchug refinery is now well positioned to market a full range of winter diesel grades, including Arctic diesel, at competitive prices. Our next objective is to reach full compliance with the Euro V specification (<10-ppm sulphur content), and we will continue to work with Criterion and Shell Global Solutions to achieve this.”