ECN s torrefaction-based BO 2 -technology from pilot to demo Jaap Kiel IEA Bioenergy workshop Torrefaction, Graz Austria, 28 January 2011
Presentation overview ECN Energy research Centre of the Netherlands Torrefaction design challenges Initial small-scale R&D ECN s torrefaction-based BO 2 -technology Pilot-scale testing Demonstration and market introduction Conclusions BO 2 -technology = the alternative to CO 2 2 ECN s torrefaction-based BO 2
Energy research Centre of the Netherlands In the dunes of Petten, North Holland ECN develops and brings to market high-level knowledge and technology for a sustainable energy system Independent research institute 650 employees Annual turn-over: 80 million Euro Main activities: - Biomass, Solar, Wind - Energy efficiency -Policy studies 3 ECN s torrefaction-based BO 2
Biomass a difficult energy source. in view of: Logistics (handling, transport and feeding) End-use (combustion, gasification, chemical processing) Difficult properties are: Low energy density (LHV ar = 10-17 MJ/kg) Hydrophilic Vulnerable to biodegradation Tenacious and fibrous (grinding difficult) Poor flowability Heterogeneous 4 ECN s torrefaction-based BO 2
Torrefaction for upgrading biomass Dry biomass 0.3 Gas 0.1 Torrefied biomass 1 Torrefaction 0.7 1 200-300 C 0.9 Process parameters Temperature: 200-300 C Energy densification (MJ/kg) 1 0.9 0.7 = 1.3 Residence time: 10-30 minutes Particle size: < 4 cm mass energy Absence of oxygen Pressure: near atmospheric 5 ECN s torrefaction-based BO 2
Torrefaction.. how difficult can it be? Small-scale coffee roasting machine in Bourg St. Maurice, France 6 ECN s torrefaction-based BO 2
Biomass torrefaction for energy applications Not straightforward! Absence of oxygen requires air-tight system Torrefaction should be considered as a separate thermal regime, distinctly different from drying, slow pyrolysis or charcoal production Characteristic features: Modestly exothermal reaction Condensables composition and behaviour Nature and behaviour of the solid product Optimum energy efficiency is crucial in view of overall cost and sustainability Reactor and process should allow large-scale production with minimal environmental impact 7 ECN s torrefaction-based BO 2
Design challenges Torrefaction process control condensables, exothermicity, product quality control (in view of subsequent densification and end-use) Cost CAPEX, OPEX, availability Energy efficiency (also in view of CO 2 footprint) heat integration use energy content torrefaction gas Feedstock flexibility Environmental impact (avoid waste streams) Plant capacity (at least 5-15 tonne/h dry input) Energy densification: torrefaction + pelletisation Torrefaction reactor and process design should be chosen carefully Dedicated pelletisation procedures should be developed 8 ECN s torrefaction-based BO 2
Initial small-scale torrefaction R&D at ECN ECN was one of the first to recognise the potential of torrefaction for biomass-to-energy purposes Initial small-scale research started in 2002-2003, revealing: Quantitative relation between torrefaction conditions (residence time, temperature) and product properties (solid + gas) for a broad range of biomass feedstocks Underlying mechanisms (structural changes in the biomass) Pelletisation behaviour of torrefied biomass Based on the small-scale research, dedicated reactor and process concepts were developed, aiming at: good process control, low investment cost, high capacity, high feedstock flexibility, high energy efficiency and minimum environmental impact To achieve high energy efficiency, heat integration using the energy content of the torrefaction gas is crucial 9 ECN s torrefaction-based BO 2
Bench-scale testing Torrefaction of willow (280 o C, 17.5 min) 20 l batch reactor Main product groups (dry basis) 100 90 80 70 60 50 40 30 20 10 0 94.9 87.5 Mass yield Energy y ield 8.0 1.4 0.1 1.7 1.6 1.4 3.4 Solid Permanent Gas Organics Lipids Reaction Water 100% 5 kg/h Auger reactor (screw reactor) Permanent gases 75% 50% 25% mass composition energy composition Organics 0% CO CO2 Other 70% 60% mass composition 50% energy composition 40% 30% 20% 10% 0% Acetic Acid Methanol 10 ECN s torrefaction-based BO 2 2-Furaldehyde Hydroxyaceton 1-Hydroxy-2-butanon Phenol Propionic acid Furan-2-methanol 5-Methyl-2-furaldehyde Acetaldehyde Methylacetate Other
Grindability of (torrefied) woody biomass 90 80 C(270,21) C(280,18) 360 320 Power consumption ( kw e /MW th ) 70 60 50 40 30 20 C(290,12) W(290,24) W(260,24) Willow (MC=10-13%) Willow (dried) Cutter wood AU bituminous coal Borssele run demolition wood D(300,11) Mill capacity (kw th ) 280 240 200 160 120 80 10 40 0 0.0 0.5 1.0 1.5 0 0.0 0.2 0.4 0.6 0.8 1.0 Average particle size (mm, volume based) Average particle size (mm, volume based) Torrefaction leads to a dramatic decrease in required milling power and increase in milling capacity 11 ECN s torrefaction-based BO 2
Reactivity of torrefied wood Lab-scale experiments to mimic pulverised-fuel combustion conditions high-volatile coal low-volatile coal torr. (300 C) demolition wood 100 torr. (280 C) prune wood torr. (280 C) demolition wood prune wood (fresh) conversion [%] 90 80 70 60 50 40 30 20 High reactivity for torrefied wood 10 0 0 500 1000 1500 2000 2500 t [ms] 12 ECN s torrefaction-based BO 2
BO 2 -technology Features: Conventional drying and pelletisation Compact dedicated moving bed technology with direct heating (no moving parts) Heat integration High energy efficiency (> 90%) Cost effective IP is patent protected Air Utillity fuel Torrefaction gas Gas recycle Combustion Flue gas Biomass Drying Torrefaction Cooling Pelletisation BO 2 pellets P 15-20% moisture Flue gas Heat exchange Flue gas 13 ECN s torrefaction-based BO 2
Pre-drying Feeding Torrefaction pilot-plant (50-100 kg/h) 14 ECN s torrefaction-based BO 2
Pilot-scale torrefaction Testing history: Start-up 2008 Over 1000 hours of operation (day runs + 50-100 hour runs); >30 tonnes of torrefied material produced Currently regular 50-100 hour runs Biomass feedstock: poplar, pine, forestry residues (softwood/hardwood mixtures), agricultural residues (POR) Conditions: 220-280 C torgas inlet temp., throughput approx. 60 kg/h (input basis) Modifications after initial tests: New continuous discharge system Modifications to reactor design (better scale-up) Modifications to the gas loop (long-duration operation) 15 ECN s torrefaction-based BO 2
Production of 1-10 tonne test batches 16 ECN s torrefaction-based BO 2
Pilot-scale torrefaction results of typical run 300 Torrefaction reactor temperatures 250 Temperature ( o C) 200 150 100 Poplar chips 13.6% moisture Mixture: poplar, spruce, birch and ash wood 27.8% moisture 50 TOR_TIA2001L TOR_TIA2001M TOR_TIA2001O TOR_TIA2252 0 15-03-10 0:00 15-03-10 12:00 16-03-10 0:00 16-03-10 12:00 17-03-10 0:00 17-03-10 12:00 18-03-10 0:00 18-03-10 12:00 19-03-10 0:00 19-03-10 12:00 20-03-10 0:00 17 ECN s torrefaction-based BO 2
Pilot-scale torrefaction general findings Smooth operation, easy start-stop High feedstock flexibility, limited pressure drop and no bridging given proper sizing of the feedstock Good control of condensables in the torgas Torrefaction modestly exothermic, reactor shows good active temperature control enabling good product quality control Torrefied product pyrophoric / self-igniting, passivation needed 18 ECN s torrefaction-based BO 2
Pilot-scale pelletisation Torrefied material from pilot-plant subjected to semi-industrial-scale pelletisation tests at CPM: Good quality pellets can be produced without additional binder But case-by-case tuning of the pelletisation conditions (e.g. die type) required Good control of torrefaction conditions essential for proper pelletisation performance 19 ECN s torrefaction-based BO 2
BO 2 -technology demonstration and market introduction ECN teamed up with Vattenfall to prepare for demonstrating the technology Contract negotiations with a technology supplier with world-wide presence for scale-up and commercial market introduction in final stage Demonstration unit scheduled for start-up by end 2011 Supporting R&D aimed at: Further process improvement and simplification Broadening of the feedstock range Further optimisation of torrefaction + densification Product quality optimisation based on extensive logistics and end-use performance testing with test batches produced at pilot/demo scale: Co-firing in pf boilers (Co-)gasification in entrained-flow gasifiers (IGCC or biofuels production) 20 ECN s torrefaction-based BO 2
In conclusion Torrefaction potentially allows cost-effective production of 2 nd generation biomass pellets from a wide range of biomass/waste feedstock with a high energy efficiency (>90%) Torrefaction pellets show: High energy density Water resistance No/Limited biological degradation and heating Excellent grindability Good combustion and gasification properties Torrefaction is a separate thermal regime and requires dedicated reactor/process design Torrefaction development in pilot/demo-phase; strong market pull for torrefaction plants and torrefaction pellets For ECN s BO 2 -technology, demo-plant in preparation and industrial partnership for world-wide market introduction nearly established 21 ECN s torrefaction-based BO 2
Thank you for your attention For more information, please contact: Jaap Kiel phone +31 224 56 4590 e-mail kiel@ecn.nl internet www.ecn.nl 22 ECN s torrefaction-based BO 2