Nov-2020

Versatile performance with BioFlux renewable diesel (ERTC)

Clean fuel from renewables is an important element in meeting energy requirements of the future. Renewable diesel has become the leading alternative as companies invest in a more environmentally conscious energy supply.

Matthew Clingerman
Sulzer GTC Technology

Article Summary

Completely fungible with petroleum diesel, renewable diesel from biomass-based feeds has lower sulphur and higher cetane than its petroleum-based equivalent and can be used without modification to existing infrastructure. Regulations and incentives are encouraging investments, placing renewable diesel at the forefront of the fuels transition.

Most renewable feedstocks are highly olefinic and contain high levels of heteroatom contaminants. Feed pretreatment followed by fixed-bed hydroprocessing is the most common means by which triglyceride or lipid-based feeds are converted into renewable fuels. Historically, hydroprocessing of petroleum-based feedstocks has been accomplished using two-phase reactors, where hydrogen is transferred from a vapour phase into the hydrocarbon liquid where it reacts at the catalyst surface. This process is often re-purposed by refiners making the switch to renewable feeds. However, utilising a conventional hydroprocessing unit invariably comes with challenges.

Trickle-bed hydroprocessing units require circulation of large volumes of hydrogen gas, and limits are pushed further as renewable feeds have increased consumption. Larger reactors and gas circulation equipment must operate under severe conditions, which also means lower throughput in post-revamp operation. Catalyst coking and over-cracking are also operational concerns due to high heat in a hydrogen-starved environment. Hydrodeoxygenation reactions are highly exothermic, generating significantly more heat than typical hydroprocessing processes of petroleum products, which only exacerbates these problems.

novel hydrotreating technology
A novel hydrotreating technology called BioFlux® has been developed to address the key issues plaguing the renewable diesel operators. BioFlux pretreatment is a thermal degradation process that uses heat to remove contaminants as an alternative to the washing and separation steps that not only have higher utility consumption, but also higher hydrogen consumption in the hydrotreating unit. BioFlux pretreatment reduces capex by more than 75% as compared to other pretreating units.

The BioFlux hydrotreating unit has been designed to overcome the key deficiencies of the trickle-bed design by completely dissolving hydrogen into the liquid. High liquid mass flux is maximised in the reactor, and the proprietary reactor internals ensure complete mixing of feed and hydrogen for even distribution across the catalyst. In the first stage, triglycerides are reacted with hydrogen to remove oxygen and saturate olefins, which generates a diesel-range hydrocarbon product. Water, CO2, and other byproducts are also generated. After byproduct removal, a portion of the first reactor product is recycled and mixed with fresh feed. This recycled effluent provides three benefits: preheat to the fresh feed, which reduces the requirement for supplementary preheat; supply of additional hydrogen; and elimination of large gas recycle. Combined, these changes lead to a 25% reduction in capex and a 25—50% reduction in opex.

Yield of diesel from BioFlux is approximately 95-99 wt%. On a volume basis, it is nearly an even ratio, i.e. one barrel of renewable diesel can be produced from each barrel of feed, which meets or exceeds relevant standards, such as ASTM D975 (US), EN590, and EN15940 (Euro). Renewable naphtha, sustainable aviation fuel, or bio-propane can also be collected as saleable product from a BioFlux unit.

Summary
Sulzer, a global leader in supplying state-of-the-art process equipment, is using its expertise to deliver world-class performance to renewable diesel producers worldwide. BioFlux technology from Sulzer GTC is a low-capex, low-opex solution for hydroprocessing of bio-based materials that increases yield and lowers hydrogen consumption. The process offers superior operational stability for extended catalyst life and is suitable for grassroots or revamp units, either standalone or in an integrated facility.

This short article originally appeared in the 2020 ERTC Newspaper, produced by PTQ / DigitalRefining.

You can view the digital issue here - https://online.flippingbook.com/view/1029582