Valorizing biogenic waste: A comprehensive analysis of steam/oxygen fluidized bed gasification of pine forest residue including syngas cleaning

Gasification of biogenic residues utilizes energy and carbon from the feedstock, thereby providing sustainable chemicals at a price that is less susceptible to electricity price fluctuations than in Power-to-X applications. This paper carries out a comprehensive analysis of a bubbling fluidized bed gasifier with a post-gasification zone (PGZ) at pilot scale (2t/d), along with a mass balance of the gas treatment. The autothermal gasifier was operated for 100 hours, during which more than 8 tons of pelletized pine forest residues were converted with steam and oxygen to syngas consisting primarily of HX2, CO, CHX4, COX2 and HX2O at ambient pressure. Located above the bubbling bed, the PGZ improves gas quality by reducing the hydrocarbon load to an extent dependent on λ. Under optimal operating conditions, a cold gas efficiency of up to 78 % was achieved at pilot scale by increasing the oxygen supply. For industrial applications, efficiency levels exceeding 85 % are expected. To meet the sulfur and chlorine content criteria for a commercially available hydrogenation catalyst, the raw gas underwent successful purification in a gas treatment facility. This plant is equipped with a filter, a raw gas scrubber, a compression and a hydrolysis, a BTEX removal and a sour gas removal using an MDEA/MEA amine solvent. The separation efficiency of each process step was evaluated using samples of the syngas, waste streams and simulations. This study validates the presented concept of cost-effective biogenic waste gasification and gas cleaning, serving as a basis for scale-up and providing a framework for industrial applications.