© Fraunhofer IGB
© Sven Döring
© Fraunhofer CBP
One focus in the field of biomass fractionation is on the pulping of lignocellulosic raw materials and their fractionation into their basic chemical components, lignin and sugar or fiber.
For the research and development of processing and fractionation technologies, a specially developed integrated pilot plant is available that enables pulping with organic solvents under increased pressures and temperatures, the so-called Organosolv technology.
The plant reproduces a large number of individual process steps for the production of fibrous materials, concentrated sugar solutions and lignin. Up to 70 kilograms of wood or 20 kilograms of stalks can be processed per batch. The facility was designed in such a way that the material and energy cycles are closed and therefore mass balances can be determined.
The pilot plant includes a digester to separate the pulp from lignin and hemicellulose. The liquid phase is treated using a patented distillation process to precipitate the lignin.
The Organosolv lignin obtained has high-grade properties, making it suitable for applications in pharmaceuticals or cosmetics, among others.
The remaining hemicellulose solution can be further processed by hydrolysis and the resulting sugar solution concentrated by evaporation to be used in fermentation as a nutrient for microorganisms or as a raw material for biofuels.
Due to the universal design of the pilot plant, other pulping processes for lignocellulose can be optimized on a pilot scale in addition to the Organosolv process, e.g. aqueous hydrolysis and digestion using acid or the soda process. The process is fully automated and data documented for balancing the processes.
By using individual process engineering units in the plant, questions in the area of thermal separation technology and extraction can also be dealt with. There is strong interaction here with the "Downstream processing" field of competence.
With our flexibly operable pilot plant and excellent equipment for conversion and processing procedures, we develop and scale biotechnological and chemical processes for the utilization of wood components up to application-relevant dimensions and support small and medium-sized companies in particular for faster product development and market launch.
The core processes that can be represented in the pilot plant are shown in the simplified plant diagram. First lignocellulose is pulped in a 400-liter reactor at up to 200°C, whereby lignin and hemicelluloses dissolve in the solvent-water mixture.
The additional tanks and heat exchangers in the tank farm permit an efficient fractional washing of the feedstock under reaction conditions and the recovery of energy in the pulping process.
From the fractionation solution enriched with lignin and hemicelluloses, lignin is precipitated by adding water or distillation of the solvent, filtered off and, after washing, dried. The solvent used is recovered completely from the filtrate and the hemicellulose sugars remain as an aqueous solution.
The organic solvent used is recovered completely from the filtrate and the hemicellulose sugars remain as an aqueous solution. The solid, fibrous residue of the fractionation is isolated and washed, dewatered and, if necessary, enzymes are added and saccharified in specially designed stirred reactors at a high fiber concentration. After a filtration stage a glucose solution is obtained which is concentrated into a syrup to stabilize it.
Fraunhofer Center for Chemical-Biotechnological Processes CBP