Catalytic Dewaxing Helps Gazprom Neft To Produce High-Quality Winter Diesel In Russia
In countries such as Russia that experience severe winter weather, the demand for winter diesel is particularly strong. The Russian government is encouraging refineries to increase the production of winter diesel to address the shortage in supply. However, producing good-quality winter diesel with the necessary cold-flow properties, such as cloud point, pour point and cold filter plugging point, is challenging for refiners.
One way that refineries have traditionally sought to achieve the required cold flow properties is through additivation. However, this is insufficient where the local weather conditions require the use of extreme winter diesel grades. Adding kerosene to the diesel oil pool is also a common solution for meeting cold flow specifications. However, both options are expensive and can detract from the refinery’s bottom line.
The Gazprom Neft refinery in Omsk, Russia, needed to increase its production of high-quality winter diesel to meet demand and to maximise its yield of high-value winter diesel fuels. It also wanted to produce additional kerosene, which is in short supply during the winter months because it is traditionally blended with diesel.
After investigating the technologies offered by different suppliers, the Gazprom Neft Omsk refinery decided to implement catalytic dewaxing technology from Shell Global Solutions and Criterion Catalysts & Technologies (Criterion). Diesel dewaxing can help refiners to enhance their margins because it avoids the need for expensive additives or kerosene blending. In addition, it enables the use of heavier or more paraffinic feedstocks that have a higher cloud or pour point, or more wax.
Catalytic dewaxing helps refiners to achieve the cold flow properties, such as cloud, pour and cold filter plugging points, necessary for marketing diesel in cold climates by preventing wax compounds from crystallising in the diesel and causing engine problems.
One of the factors that prompted the Gazprom Neft Omsk refinery to choose the Shell Global Solutions–Criterion option was that it wanted to use an old diesel hydrotreater with two parallel trains to produce its winter diesel. This hydrotreater was commissioned in 1967 but had limited use for the production of ultra-low sulphur diesel. Shell Global Solutions devised a solution that enabled the refinery to use this unit and recommended the use of its advanced reactor internals and the SDD-800 dewaxing catalyst from Criterion.
The two-phase revamp was implemented without major changes and took account of the process constraints of using an old unit, for example, the low hydrogen partial pressure and the limited space velocity.
The first phase involved installing a connecting pipeline from the hydrotreating section to the dewaxing section and a pipeline to withdraw treated winter diesel from the unit; replacing the dewaxing section reactor internals and the catalyst systems; and removing internal pipes from the reactors. The two trains of the unit were operated in parallel during the first phase of the project. Hydrotreatment was completed in train one. The dewaxing was carried out in the second train.
During the second phase, the unit was brought back to the design scheme with double the production of winter diesel through parallel operation of the two trains. Hydrotreated diesel fuel produced in two of the refinery’s other units was used as the feedstock.
Ivan Gorodok, Chief Project Engineer, Gazprom Neft Omsk refinery, says it was a novel application for the refinery. “This was our first attempt to use a base metal dewaxing catalyst in a ‘clean’ (second-stage) environment and one that also gave additional economic benefits for the refinery. It managed to achieve very good product yields and made more high-quality ultra-low-sulphur and winter diesel.”
Previously in Russia, the main standard for diesel was GOST R 52368-2005 (equivalent to European standard EN 590), which prescribes the ASTM D86 95% distillation point for winter diesel as 340°C. The application of the dewaxing technology enables Gazprom Neft to produce winter diesel with an ASTM D86 95% distillation point of 360°C, as for summer diesel.
This generated a good incentive to create a new standard for winter diesel: GOST R 55475-2013 Dewaxed Winter Grade Diesel Fuel and Arctic Grade Diesel Fuel. This standard allows the production of relatively heavy winter diesel in Russia, which was only possible previously through additivation.
“With the technology we have implemented at Omsk,” says Gorodok, “it is possible to produce winter diesel with the same distillation point as summer diesel and that meets international standards for an end boiling point of 360°C. This diesel is better for engines because it has a higher density and calorific value, so produces more power, and it has higher lubricity. We have also been able to increase our production of kerosene.
“The application of modern Shell Global Solutions–Criterion dewaxing technology enables us to produce high-quality winter and extreme-winter-grade diesel fuels at minimum capital cost, even in relatively old hydrotreating units with low hydrogen pressure, and with minimum changes to process configuration.
“Despite the fact that the trial on the new technology was carried out using old equipment, we obtained good results. The targeted dewaxed product yield was within 90–93%. We were pleased to produce high dewaxed product yields after the first year of operation. We required a substantially lower quantity of dewaxing catalyst to give a relatively high yield of the target product, which resulted in much lower overall project costs,” concludes Gorodok.
Gazprom Neft will continue to work with Shell Global Solutions and Criterion and plans to use the new technology in revamps at its other refineries in Russia to produce diesel for extreme winter conditions.
For more details on Shell Global Solutions’ catalytic dewaxing technology.