Pyrolysis & Char Processes Fernando Preto CanmetENERGY, Natural - PowerPoint PPT Presentation

Pyrolysis & Char Processes Fernando Preto CanmetENERGY, Natural Resources Canada

Charcoal Production & Use Pyrolysis in late medieval foundry processes Georgius Agricola, De Re Metallica Libri XII, MDLVI English translation 1912 by Herbert Hoover

Char Production How can we optimize char production?

Pyrolysis Stages Temperature Process (Overlap) Major Products Heat <200ºC Drying H20 IN 230ºC-250ºC Depolymerization Acetic acid, Methanol, CO2, CO IN 250ºC-280ºC Torrefaction Extractives, CO2, CO IN 280ºC-500ºC Devolatilization Organics, Tars, CO2,CO OUT 500ºC-700ºC Dissociation/Carbonization CO, H2 IN >700 ºC Gasification H2, CO IN

Time to Complete Pyrolysis as f(size) X. Wang et al 2006

Yields vs Residence Time 40 35 30 25 Yield % Liquid 20 Gas 15 Solid 10 5 0 2.5 secs 5 secs 20 secs Vapour Residence Time T=500 C

Charcoal Yield as f(size) X. Wang et al 2006

Product(s) Yield as f(Temperature) X. Wang et al 2006

Product Distribution Mode Conditions Liquid Char Gas Moderate temperature, Fast pyrolysis 75% 12% 13% short residence time Low temperature, very long Slow Pyrolysis 30% 35% 35% residence time High temperature, long Gasification 5% 10% 85% residence time. A.V.Bridgwater

Species Migration: S, N J. Hrbek et al 2006

Species Migration: Cl, K J. Hrbek et al 2006

Yield of Traditional Charcoal Processes  Batch processes:  Earth pits and mounds >10%  Brick, concrete, and metal kilns 20-25%  Retorts 30%  Continuous processes:  Retorts (Lambiotte) 30-35%  Multiple hearth reactors (Herreshoff) 25-30% FAO Rinsing Retort

Pyrolysis: Industrial Research in Canada ABRI-Tech Airex Alterna ABRI-Tech Organic Power Airex Titan Agritherm… Agritherm Ensyn Dynamotive…

Courtesy NREL

Maximizing Charcoal Yield

Maximizing Charcoal Yield • Low pyrolysis temperature (<400ºC) (but also lower fixed carbon content) • High process pressure (1 MPa) (higher concentration of pyrolysis vapor increases rate of secondary reactions) • Long vapor residence time (extended vapor/solid contact promotes secondary coke forming reactions) • Low heating rate (slower formation and escape of organic vapors) • Large biomass particle size (low thermal conductivity of biomass results in slow heat and mass transfer rate within particles)

Thank You! Questions? Fernando Preto preto@nrcan.gc.ca Tel: 613-996-5589 http://canmetenergy.nrcan.gc.ca/