Grupa LOTOS will upgrade the four sulfur production units operating at its refinery in Gdańsk. This will enable the refinery to desulfurise 900 thousand tonnes per year of fuels recovered, under the EFRA Project, from high-sulfur heavy residue remaining after crude oil processing. The modernisation of the existing desulfurisation units (Claus facilities) is much cheaper than the construction of a new unit would be, while guaranteeing the same performance. The modernisation project is being prepared by Kinetics Technology S.p.A. (KT) and Parsons, specialist providers of refining technologies.

The companies have been the licensors and contractors of the Claus sulfur production units operating at the LOTOS refinery. KT is also the general contractor for the EFRA Project, which will enable LOTOS to increase the production of fuels by almost one million tonnes within the next three years, while maintaining the current volume of crude processed. LOTOS will also discontinue manufacturing high-sulfur heavy fuel oil, with a shift in the production mix towards the highest quality fuels. Another product will be sulfur recovered during crude oil processing.

350 tonnes of sulfur daily

The modernisation will increase the daily output of sulfur produced from hydrogen sulfide by the four Claus facilities by a total of 80 tonnes, from the current 270 tonnes to 350 tonnes. This will require feeding oxygen into the Claus facilities, in order to enhance their throughput.

“The use of oxygen in these facilities is very economically viable. The decision to upgrade the ‘Clauses’ to ‘oxy-Clauses’ was preceded by specialist oxygen-assisted production tests conducted by Linde. As the test results were positive, we started negotiations with the licensors concerning the modernisation of the facilities,” says Tadeusz Wróbel from the Engineering Support Office for the EFRA Project.

Linde will build an oxygen production plant, whose output will be fed into the Claus facilities. As a result, hydrogen sulfide processing, which will be performed at a temperature of approximately 1,400°C, will be more efficient.

“The output of sulfur is limited by the pressure in thermal reactors, and this pressure is already at its safe maximum. However, if the air fed into the facilities contains more oxygen (and less nitrogen), the volume of feedstock processed, and thus of sulfur produced, will increase,” explains Tomasz Klonowski from Grupa LOTOS’ Production Engineering Office.

The planned upgrade of the four Claus facilities will increase the rate of hydrogen sulfide processing. The work will include replacement of burners in the thermal reactors and afterburners, as well as of process gas heaters. The two residual gas treatment units will also be revamped.

Three stages of desulfurisation

A part of the products of the DCU unit being constructed under the EFRA Project will be desulfurised on the DCU unit itself, where dry gases and LPG will be treated in the amine washing section. The gasoline fraction will be directed to the nearby new Coker Naphtha Hydrotreating (CNHT) Unit. The main coking products, diesel oil fractions, will flow in two streams to the hydrocracking (MHC) and hydrodesulfurisation (HDS-520) units, to be processed into fuels and desulfurised. The resulting hydrogen sulfide product will be fed into the Claus facilities. The Claus facilities with an increased sulfur production capacity will be re-launched in spring 2017, after the refinery’s maintenance shutdown.

Communications Office, Grupa LOTOS S.A., ul. Elbląska 135, 80-718 Gdańsk, Poland, tel. (+48) 58 308 87 31, (+48) 58 308 83 88, e-mail: media@grupalotos.pl