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Mobile and Flexible Industrial Processing of Biomass

Periodic Reporting for period 3 - MOBILE FLIP (Mobile and Flexible Industrial Processing of Biomass)

Reporting period: 2018-01-01 to 2018-12-31

The overall objective of the project was to develop mobile and flexible units for the conversion of underutilized solid lignocellulosic biomass residues into higher value intermediates and products. The aim was that the units would be flexible and utilize various lignocellulosic side streams and wastes from forestry, agriculture and solid residues from food industry. These streams are typically seasonal and generated in remote locations, thus mobility of the unit is important. Transportation costs would thus be reduced by treating biomass near its source. Four potential technologies were successfully demonstrated: hydrothermal treatment e.g. to speed up biogas formation, torrefaction, slow pyrolysis for the production of biochar and liquid fraction, and pelletising. Suitable raw materials and potential business scenarios were identified for each technology.
The suitability of biomass value chains from feedstocks via processes to products were evaluated. The work included biomass selection, procurement and characterization, process tests and modelling at lab and pilot scale and product quality tests. The biomasses were selected based on availability in Europe and diversity in terms of species and climate: “wet” biomasses (grape pomace, corn stover, corn leaves, coffee cake, brewery and greenhouse residues) suitable only for hydrothermal processes, and “dry” biomasses (Scots pine bark and forest residue, beech chips, poplar, willow, reed canary grass, wheat straw, sunflower shells, grape seed cake and corn cob) suitable for a wider range of processing. It was found that for all technologies, the process conditions need to be optimized separately for the various raw materials in order to reach optimal product properties.

Work by SPC and SLU on pelletizing of a wide variety of non-treated and torrefied materials has led at SLU to development of an innovative instant in-die steam conditioning device for improved process control and flexibility, which has been benchmarked with the pelletization tool of RAGT. Animal bedding was identified as a potential end use for the pellets. Biogold’s original target was hydrothermal pretreatment for saccharification. However, their process was found to be more feasible for biogas production. The present technology, in a somewhat bigger scale, will potentially be a realistic approach for commercialisation. ETIA constructed a new type of torrefaction unit with integrated drying and torrefaction, feasible for mobile application. Torrrefaction is a suitable technology for various solid side streams. CEA helped to create better understanding on the torrefaction process using various processing equipment and conditions. Raussi constructed a mobile unit for the production of biochar from dry, solid biomasses. The main product is biochar, but with the novel technical solution that Raussi has patented, also potentially valuable liquid fractions can be collected separately. VTT’s bench-scale tests gave information about the yields of biochar, liquid and gas. VTT studied the potential of hydrothermal carbonization (HTC) in laboratory scale, especially for the treatment of wet biomass residues. This process was not demonstrated as a mobile unit. Wet oxidation tests on HTC liquid fractions were performed at RISE Processum together with VTT to explore how their environmental impacts can be minimized. Detailed studies on chemical and physical activations of biochar were performed, benchmarking HTC and slow pyrolysis biochars.

In order to evaluate the value of the products obtained by the mobile processes, CHIMAR produced particleboard type panels from raw biomasses, products and by-products from these processes aiming at replacing the presently used wood or improving the properties of the panels. Typical pellets and biochars proved unsuitable materials for particleboards but panels with torrefied products showed improved thickness swelling which makes them suitable for applications where panels of high resistance to moisture are required and low mechanical properties are acceptable.

Luke characterized the biochars and tested them as soil improving materials and the liquid fractions as biopesticides and for manure acidification. These results emphasize the importance of end-product characterization as well as the need for detailed studies for each specific end-use purpose. A common roadmap was defined with Luke for characterization of biochar and liquid produced in the mobile slow pyrolysis unit.

LCA studies were carried out by VTT (slow pyrolysis & HTC), RISE (pelletizing), and FCBA (torrefaction). The product systems were subdivided into a set of unit processes, with respective material and energy flows. Potential business cases were evaluated by the lead of RISE, taking into account all relevant policy aspects, legislation and funding opportunit
The targets for development beyond the state of the art were set in the beginning of the project. They have been reached as follows:

• Mobile, small-scale systems developed for at site treatment of spatially scattered raw material sources for compaction and/or thermal conversion.
• Two technologies developed that are feasible also for wet organic raw materials on site, strongly reducing biomass volume and mass.
• Torrefaction was tested and optimized for several biomass types, partly coupled with pelletization.
• Four technologies were demonstrated as continuous mode operation: hydrothermal pretreatment, torrefaction, slow pyrolysis and pelletising.

Pellet production in small scale enables tailored production for small size customers for example for animal bedding. Big users of biomass are not interested in smaller raw material sources, and small diameter trees are not optimal for producing chips for heat terminals. Also mobile production might be interesting for biomass owners, if the buyers pay a higher price for the raw material than bigger industrial customers.

Torrefaction is an interesting alternative if high value water treatment absorbent materials can be produced. In the future, if rapid CO2 emission reductions are needed, torrefied biomass can be mixed together with coal in an existing coal fired power plant. Torrefied material can be mixed in greater amount than white pellets.

Slow pyrolysis has the advantage of yielding three products with added value: biochar, distillate and heat. A slow pyrolysis unit can be constructed and operated so that the ratio of the product types can be adjusted, which helps to balance the varying seasonal heat demand.

Mobile hydrothermal processes can be used to treat various raw material sources that are too small for stationary plants. The products may be used for conversion into sugars for biotechnical processing or for biogas production. Under more harsh conditions, biocarbon can be produced, which can further be converted into high value activated carbons as a separate post treatment step.