New ethylene storage tank will reduce regular flaring in half
- Slovnaft launches new ethylene storage tank
- regular turnarounds of the production unit in the petrochemical part of the refinery and flaring will be gradually halved by the end of the year
- total CO2 savings will reach 2558 tonnes per year
- the construction of the new storage tank cost almost 70 million euros
Bratislava, October 16, 2023 – Slovnaft has launched a new ethylene storage tank. The investment of almost EUR 70 million will reduce the need for regular shutdown of the LDPE4 polyethylene production unit by half. This will reduce the volume of CO2 emissions and electricity consumption, and residents in the surroundings of refinery will notice a reduction in regular flaring, i.e. burning on flares which is an essential part of production units shutting down. Besides the light effect, the flaring is usually accompanied by an increased noise level.
„While until now we needed to shut down the production unit in the petrochemical part of the refinery (LDPE4) an average of 24 times a year due to the raw material balance, by increasing the storage capacity of ethylene, which is the basic raw material for the production of polyethylene, the need to shut down LDPE4 will gradually decrease to 12 times a year by the end of the year,“ explains Ondrej Zákutný, head of Investments at Slovnaft, noting that flaring, i. e. burning of raw material on flare stacks, is an important safety feature when shutting down petrochemical production units.
The new ethylene storage tank is designed for the storage of liquefied ethylene. The non-pressurised double-walled cylindrical vessel with an outer diameter of 30 metres and a height of 26.7 metres can hold 6,000 tonnes (10,000 m3) of liquid ethylene. It is stored there at a temperature of -103 °C and an overpressure of 8 kPa(g).
„The new ethylene storage tank will allow for smoother operation of LDPE4, while reducing the risk of forced shutdown of the Ethylene Unit where ethylene is produced. The total CO2 savings amount to 2558 tonnes per year,“ says O. Zákutný.
The BAT (Best Available Technology) principle was used in the construction of the ethylene storage tank. The main contractor was OT Industries, which, like Slovnaft, belongs to the MOL Group. The storage tank itself was made by the renowned Italian company Paresa, the compressor packages were supplied by Howden ČKD, NEAD and Aerzen. Two cryogenic submersible pumps from the American company Ebara are installed in the tank and the evaporation of ethylene is carried out by an exchanger from Linde. Two unique operations were also part of the construction.
„The roof of the storage tank was built inside and then was pushed on top of it by air. The roof itself weighs more than 100 tonnes and its construction, as well as the shell itself, was manufactured with millimetre precision in order to realise this lift,“ explains O. Zákutný.
Another exceptional operation was the drilling and plugging of a DN1000 diameter exhaust pipe at a 45-degree angle using the T.D. Williamson method. Such a specific connection method has never been implemented anywhere in the world before and was specially developed for Slovnaft by SEPS.
A video of the construction of the new ethylene storage tank, which will improve the operation of two production units, can be viewed here:
The ethylene storage tank construction milestones
- September 2016 – investment approval
- August 2017 – contract signing
- July 2018 – start of implementation
- July 2022 – mechanical completeness, delivery of the work from the contractor
- July 2022 – October 2023 – test operation – testing , adjusting and putting the unit into test run
- October 2023 – set date for switchover to permanent operation
Ethylene storage tank in numbers
- Total investment: EUR 68.81 million
- Outside diameter: 30 m
- Height of the storage tank up to the roof dome (without reinforced concrete base): 26.7 m
- Operating capacity of ethylene: 6000 tons (10 000 m3)
- Storage temperature: -103 °C
- CO2 savings: 2558 tonnes per year
