Impact of Inorganics in the Industrial Processing of Biomass Nikolai DeMartini Johan Gadolin Process Chemistry Centre Åbo Akademi University Turku, Finland
Bagasse & Pine 3000 2500 Leached Acid soluble in HCl salt Leached Ion exchangeable in Acetate Leached Water in soluble H2O mg/kg dry bagasse 2000 1500 1000 500 0 Bagasse Pine Bagasse Pine Bagasse Pine Bagasse Pine Bagasse Pine Bagasse Pine Bagasse Pine Bagasse Pine K Ca Mg Cl P S Si Al Zevenhoven et al. Energy and Fuels, In press http://dx.doi.org/10.1021/ef300621j Werkelin et al. Fuel 2010
Examples Ca in pulping Role of alkali in thermal conversion: Torrefaction Pyrolysis Low Temperature Corrosion in Biomass Boilers
Fate of Ca during alkaline pulping During pulping, Ca released from wood and binds to organic anions Eventually, these org- Ca bonds break and CaCO 3 precipitates on fibers and heat transfer surfaces Calcium Conc., mg/l 140 120 100 80 60 40 20 0 AA=18%, Sulfidity=30% Control Add 0.25mol/L Na 2 CO 3 0 40 80 120 160 200 Time, min
Implications In alkaline pulping - CaCO 3 scales heat transfer surfaces In new fractionation concepts Ca and other metals in wood bind to organics, affecting material applications
Examples Ca in pulping Role of alkali in thermal conversion: Torrefaction Pyrolysis Gasification Low Temperature Corrosion in Biomass Boilers
Torrefaction of biomass Andritz ACB Process, Austria (1 t/h) Temp.: 240 300 C 1 atm pressure ~15-45 min Torrefaction Demonstration Plants - WPAC November 2012 7 (Andritz)
Benefits Improved storage properties Higher energy density possible Reduced water uptake Reduced biological decay Improved grindability Can use same grinders as for coal Better grindability Lower energy consumption Smaller particles
Demineralization & Doping of Biomass Method to study the influence of individual metals Biomass demineralized with 0.01M EDTA solution, then 0.01M HCl, both steps 2h at room temperature Doping 0.05M metal nitrate solution, solution ph adjusted with metal hydroxide to change level of loading
Kinetics of Torrefaction Spruce wood with different levels of doping torrefied at 5 temperatures Rate constants determined for a 2 step kinetic model Pre-exponential factors found to be a linear function of K Kinetic model found to describe kinetics torrefaction of other fuels tested: aspen, straw and miscanthus
Spruce Torrefaction Effect of K Khazraie Shoulaifar, Fuel, 2016
Effect of K on Torrefaction - Modeling 1.2 1 0.8 240 C Mass Yield % 0.6 0.4 280 C 0.2 0 Raw Straw K=0.9% Experiment ------- Model 0 5 10 15 20 25 30 35 40 time (min) Khazraie Shoulaifar, Fuel 2016
Possible Material Applications of Heat Treating Doped Wood In vivo studies in rabbit femurs have shown that heat treated wood is osteoconductive, whereas untreated wood was not [Rekola et al.] The heat treated wood was not well characterized
Implanting heat treated-wood in rabbit s bone Rekola, J. et al. The effect of heat treatment of wood on osteoconductivity. Acta Biomaterialia 5 (2009) 1596 1604
Possible Use of Alkali One torrefaction study found an increase in carboxyllic acid sites after torrefaction of K 2 CO 3 doped biomass Is it possible to increase the number of anionic sites by torrefying doped wood? These sites could be used to bind cations such as Ca for biomaterial applications... we start analyzing samples this week...
Examples Ca in pulping Role of alkali in thermal conversion: Torrefaction Pyrolysis Low Temperature Corrosion in Biomass Boilers
Metso supplies a bio-oil production plant to Fortum Joensuu power plant in Finland Demonstration plant will produce bio-oil from forest residue Bio-oil capacity 30 MW Annual production 50 000 t, 210 GWh Forest residue usage 225 000 solid-m 3 /year
Bio-oil production technology Metso DNA automation system High pressure steam Turbine Electricity Non-condensible gas District heat Forest residue Condenser Crusher Drying Sand and coke 500 ºC Sand 800 ºC Fluidized bed boiler Pyrolyzer Bio-oil
Influence of Metal Concentration in Wood on Distribution of Pyrolysis Products 70 Char Bio-oil Gases 60 50 Yield (wt-%) 40 30 20 10 0 0 10 20 30 40 50 60 70 80 90 C (μmol/g) K as circles ( ) Na as squares ( ), Ca, Mg, Mn as diamonds ( ) Aho, A., Bioresource Technol. 2013
Examples Ca in pulping Role of alkali in thermal conversion: Torrefaction Pyrolysis Low Temperature Corrosion in Biomass Boilers
Ash Forming Elements Low Temperature Corrosion New research indicates that the lowest acceptable temperature of flue gas determined by hygroscopic nature of salts Every 10 C of heat recovered from flue gas 0.5% improvement in thermal efficiency Industry will be able to improve biomass boiler effeciency by 2-3%
Salt: Precipitator Ash 1 H 2 O: 27 vol-% Exposure: 24h Before wash 80 C 90 C 70 C 100 C 110 C After wash
Summary Inorganic chemistry plays a role in most industrial processes for biomass and waste New interesting questions continuously arising from industry as technology advances
Thank you! Questions?