It’s electrifying!

Steam crackers go electric

Steam crackers go electric

The use of electricity for heating – ideally from renewable sources – has the potential to massively reduce CO2 emissions. But can this concept be transferred to the petrochemical industry? BASF, SABIC and Linde certainly believe so. They are working on a joint e-furnace project with the potential to cut CO2 emissions by more than 95 percent!

Steam crackers play a central role in the production of base chemicals. Positioned at the heart of petrochemical value chain, they require huge amounts of energy to break hydrocarbons down into olefins and aromatics. Typically, the reaction is conducted at temperatures of about 850 degrees Celsius in steam cracker furnaces. Today, these temperatures are reached by burning fossil fuels – which inevitably results in high emissions of carbon dioxide. This could change, however, based on a collaborative e-furnace project bringing together BASF, SABIC and Linde. “Our aim is to build an electrically heated steam cracker demonstration unit that operates without the need of hydrocarbon fuel,” explains Martin Hofstaetter, Senior Process Engineer for Sustainable Hydrocarbon Solutions at Linde. “If electricity from renewable sources is used to power the e-furnace, this new steam cracker technology has the potential to reduce the direct carbon emissions released by one of the most energy-intensive processes in the chemical industry by 95 percent or more.” The remaining carbon emissions include emissions by decoking or unavoidable small flaring activities during start-up and shut-down for regular turnarounds.

World’s first demonstration plant for large-scale electrically heated steam cracker furnaces in Ludwigshafen
Steam cracker of BASF in Ludwigshafen

Three partners, one mission

BASF, SABIC and Linde celebrated the ground-breaking of their joint project at the BASF Ludwigshafen complex in Germany at the end of August 2022. “This project demonstrates how global companies can successfully collaborate by combining their expertise in technology development, engineering, procurement, construction and operation. The development and successful operation of this demonstration plant will be a major milestone on the path to making sustainable solutions available to the petrochemical industry.  We are proud to be part of this breakthrough project,” says Jürgen Nowicki, Executive Vice President Linde plc and CEO of Linde Engineering. BASF and SABIC have extensive know-how and intellectual property in the development of chemical and petrochemical processes, as well as long-standing experience and knowledge in the operation of steam crackers. “As the engineering, procurement and construction (EPC) partner, our role is to contribute our know-how and intellectual property in the development and delivery of steam cracker furnace technologies and to drive the commercialization strategy,” explains Hofstaetter. The demo plant is to be integrated into the infrastructure of an existing BASF steam cracker in Ludwigshafen. The goal is to demonstrate the feasibility of continuous olefin production using electrical energy as the heat source and to provide a reference for an industrial-scale plant.

Decarbonization through electrification

“The cracking process in an electrically heated steam cracker is essentially the same as in a conventional plant,” notes Rainer Kemper, Technology Advisor for Sustainable Hydrocarbon Solutions, coordinating all Linde Engineering efforts for development and commercialization of this new technology. “So we are developing a concept that basically enables existing plants to be retrofitted. That being said, electrification of a steam cracker represents an impressive technical breakthrough.” The e-furnace technology almost completely eliminates CO2 emissions from the furnace section during normal operation due to the absence of direct emissions. Carbon emission savings of 95 percent or more are possible. Using renewable energy will also lower indirect emissions. Other anticipated benefits of the e-furnace design include improved and more uniform heat input, which enhances cracking performance and reduces the build-up of coke in the reactor. This may extend on-stream time between decoking operations, further contributing to lower total CO2 emissions.

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Electricity as heat source

“The design of the electric furnace can cope with all types of feedstock used in the petrochemical industry,” says Kemper. “So we’re talking everything ethane to heavy fractions from refinery processing, and including bio-naphtha/gas oil and pyrolysis oil – a secondary raw material obtained from the chemical recycling of plastic waste.” Two different heating concepts are being investigated in the demonstration plant: direct and indirect. With direct heating, an electric current is applied directly to the process tubes inside the reactor. This provides the thermal energy required to produce the chemical reaction converting the feed into olefins and aromatics. Indirect heating involves applying an electric current to particular heating elements that are brought to the necessary temperature. They in turn heat the process tubes by radiative heat transfer. “We believe that each of the two heating concepts will bring their own advantages, which is why we are examining both in the demo plant. We will be able to quantify this once we bring the plant on stream,” adds Matthias Mayerhofer, product manager at Selas-Linde. With its specific know-how in design and construction of cracking and other process furnaces, Selas-Linde acts as a fully integrated project partner in the realization of the demonstration plant. The capacity of the demonstration plant is selected to enable a flawless scale-up to commercial size cracking furnace capacities. The e-furnace demonstration plant will consume up to 6 MW of renewable energy and process around four tons of hydrocarbons feed.

Comparison conventional furnace and E-Furnace
Comparison conventional furnace and e-Furnace

Surplus methane as a bonus

E-furnace highlights include improved thermal efficiency. More than 95 percent of the electrical power can be directly utilized in the cracking coils, partially heating the feed and conducting the cracking reaction. By contrast, a conventional fired furnace typically transfers only 40 to 45 percent of the fired duty to the coils. The remaining heat in the flue gas is generally partially recovered for secondary low-temperature use like feed preheating or steam generation. By improving efficiency, electrification thus speaks to the sustainability and decarbonization trends that are driving industry worldwide.

This resonates with BASF’s commitment to sustainability. “BASF’s mission is to achieve climate neutrality, and electrification of the hugely energy-intensive steam cracker is a significant milestone in our transformation journey towards net zero,” commented Dr. Martin Brudermüller, Chairman of the Board of Executive Directors of BASF SE. 

Heating the steam cracker by electricity provides yet another benefit in the form of surplus methane. “Since the plant is not heated by fuel gas, the methane that forms in the steam cracking process as side product can be re-used as a natural gas replacement, for example, or as a chemical feedstock to produce ammonia, CO, H2, methanol or acetylene,” Hofstaetter explains.

Developing pathways to sustainability
Developing pathways to sustainability

First of its kind

Kemper acknowledges that Linde is not the only company pushing the electrification of steam crackers: “Several companies have their own ideas and research projects in this area, which shows that carbon abatement technologies are generally on industry’s radar. We and our partners are the first companies with the ability to build and operate an industrial-scale e-furnace demo.” The plant is expected to start operations in Ludwigshafen in 2023. Following completion of a thorough and extensive demonstration phase, the experts have earmarked the end of 2024 for general commercialization. This milestone will mark yet another large step of the petrochemical industry’s decarbonization journey.

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