Jan Klok, Desirée de Haan, Joost Timmerman and Rieks de Rink, Paqell B.V., the Netherlands, outline a number of differentiators that make biological desulfurisation suitable for the rising biofuels market.
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n 2015, 196 countries signed the Paris Agreement, an international treaty with the goal of limiting global warming to well below 2°C. To achieve this, countries have set net-zero greenhouse gas emissions targets that involve both emissions abatement and reduction. Production of biofuels, e.g. fuel produced from biomass through contemporary processes, is undergoing a tremendous expansion with new biofuel projects being executed.1 When hydrogen sulfide (H2S) is formed during the production of biofuels, desulfurisation is required to control the emission of sulfur compounds. For projects with a high sulfur load, i.e. >100 tpd of sulfur, the combination of the amine and Claus process is the most cost-effective desulfurisation line-up. However, for gas streams with intermediate and low sulfur loads (e.g. up to 20 tpd of sulfur), several commercial technologies are available. The sulfur load of a typical biofuel project is in this range. In addition, the off-gases associated with biofuel production typically have a very unfavourable CO2/H2S ratio. Therefore, the
traditional Claus technology is not a suitable desulfurisation process for biofuel projects. Besides the economics (i.e. OPEX and CAPEX), other project specific requirements determine which technology is most suitable to apply. For example, flexibility, project timeline and CO2 footprint are often important considerations in the selection of the most adequate desulfurisation technology.2 The concept definition is known to be crucial for successful project development. Recently, several biofuel projects located in the US, Europe, and Asia, selected the Thiopaq O&G (TOG) biological desulfurisation process. This article discusses essential differentiators of this technology to highlight its suitability for sulfur recovery units (SRUs) in biofuel projects.
The technology Thiopaq is a biological desulfurisation process that uses naturally occurring bacteria to oxidise H2S to biological elemental sulfur. The process has its origins in biogas treatment and more than
HYDROCARBON 19
ENGINEERING
October 2021
