Decarbonisation Technology - February 2024 Issue

Strategies to maximise profitability in HVO complexes A review of some of the challenges involved in processing hydrotreated vegetable oil and the available solutions to optimise plant profitability

Jay Jeong, Eva Andersson and Bent Sarup Alfa Laval

G iven the ever-increasing focus on the interest in biofuels and the pressure to increase their production are higher than ever. Fatty acid methyl esters (FAME) biodiesel has served the industry well for many years as an additive to petroleum-based diesel. However, it has significant limitations with respect to blending ratio, and it cannot be used for jet fuel. These factors restrict its potential to replace fossil fuels. A more viable solution has emerged in the form of renewable diesel or sustainable aviation fuel (SAF), produced through hydroprocessing of fossil-free feedstock or so-called hydrotreated vegetable oil (HVO) processing. With HVO processing, production capacities of more than 10,000 bbl/day are achievable, and both renewable diesel and SAF can be produced with quality that is equal to or better than that of traditional petroleum-based fuels. Moreover, reducing Scope 3 CO₂ emissions and closing the gap on carbon neutrality, with an optimally designed pretreatment system, the HVO process can handle a wide variety of feedstocks, ranging from vegetable, animal or even waste fats and oils to second- generation feedstocks, such as pyrolysis or hydro-pyrolysis oils generated from biomass. Due to these advantages, many existing refineries are now implementing HVO processing, whether through drop-in co-processing of bio-based feedstock in existing diesel hydrotreating units (DHT), by revamping an existing hydroprocessing unit or by integrating a new grassroots HVO processing unit into the existing plant. Additionally, new entrepreneurial companies are entering the fuel

market and constructing their own stand-alone HVO complexes. The investment in an HVO complex is typically higher than that for a traditional FAME plant by at least one order of magnitude. To achieve economies of scale, the complex is commonly designed for a higher capacity. In addition, for a complete stand-alone HVO complex, several process units are required: • Pretreatment unit (PTU) for bio-based feedstock • Hydrogen production unit (HPU) • The HVO process unit itself • Sulphur recovery unit (SRU), including amine treatment unit (ATU), tail gas treatment unit (TGTU) and sour water stripper (SWS) • Wastewater treatment unit. With the exception of a bio-based PTU, these processes are typical in most refineries. However, the feedstock in HVO processes is different, which poses new challenges for the refinery operators. To maximise plant profitability, feedstock flexibility, plant cycle length, and product yield must all be maximised. Meanwhile, the risk of equipment corrosion and fouling must be minimised, along with utility consumption (energy and water). Similarly, waste handling must be optimised. The following sections will explore some of the challenges in HVO processing, highlighting solutions available to maximise plant profitability. Feed pretreatment unit One of the most important success factors for the HVO complex is the feed PTU. Without proper feed pretreatment, the impurities present in bio-based feedstocks can lead to issues such