Pyrolysis, Char and Energy

Transcription

1 Pyrolysis, Char and Energy Fernando Preto CanmetENERGY, Natural Resources Canada The Canadian Biochar Initiative, Inaugural Meeting December 12, 2008, Ste Anne de Bellevue

2 About CanmetENERGY CanmetENERGY is the science and technology arm of the Energy Technology and Programs Sector of Natural Resources Canada

3 CanmetENERGY assists industry to develop cleaner, energy-efficient and cost-effective biomass conversion processes. The Biomass & Renewables Group focuses on optimizing the performance of biomass energy technologies and developing new products and technologies for sustainable development.

4

5 Charcoal or Biochar Pyrolysis produces charcoal, which is called biochar when buried in the ground Carbon from the waste biomass is retained in biochar and permanently sequestered in the soil, effectively removing that carbon from the atmosphere. The carbon in a ton of biochar is equivalent to 3 to 3.5 tons of CO2. Biochar is not only a carbon sink, it increases soil fertility increasing cat-ion exchange and water retention capacity in soils, while reducing nutrient leaching and providing a "coral reef" for soil microorganisms thereby significantly increasing productivity and crop yield.

6 Charcoal or Biochar If charcoal is used for energy can it be called biochar? Ultimate goal is still to optimize solid carbon retention (char production) whether the objective is to use it as a fuel/feedstock or as soil remediation What is the best way to optimize char production?

7 What is Pyrolysis? Pyrolysis is the thermal decomposition of biomass (organic material) at elevated temperatures, in the absence of oxidants such as air or oxygen. Pyrolysis of solid biomass produces solid (char) and vapour containing the products of decomposition. Part of the vapour can be condensed to produce a liquid (bio-oil). The distribution between solid, liquid and noncondensable gases depends on the biomass and conditions of pyrolysis (temperature and time).

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

9 Pyrolysis: The Future GHG Neutral; Improved Fuel Properties; Value Added Byproducts Ensyn Dynamotive ABRI Tech Alterna Organic Power Titan Agritherm Activated Carbon Resins Food Flavoring Bio-Fuel

10 Char Production How can we optimize char production?

11 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 >700ºC Gasification H2, CO IN

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

13 Yields vs Residence Time Yield % secs 5 secs 20 secs Liquid Gas Solid T=500 C Vapour Residence Time

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

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

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

17 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

18 Pyrolysis: Industrial Research in Canada Ensyn Dynamotive ABRI Tech Alterna Organic Power Titan Agritherm

19 Maximizing Charcoal Yield Alterna, McBride, BC

20 Organic Power, Chilliwack, BC

21 Courtesy NREL

22 Maximizing Charcoal Yield

23 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)

24 What is impetus for using charcoal/biocarbon as industrial energy?

25 OPG Coal Power Production Courtesy OPG

26 Maximizing Charcoal Yield Courtesy OPG

27 Maximizing Charcoal Yield Fuel Properties Density & Grindability Courtesy OPG

28 Biomass Fuel Density is Low Equivalent Energy Content Straw Wood Coal

29 Grindability: Pulverizer Performance Biomass is Plastic not Brittle

30 Charcoal or Biochar Charcoal is brittle and not plastic pyrolysis breaks down the hemicellulose matrix and depolymerizes cellulose Heating Value MJ/kg Energy Density 9-11 GJ/m3

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

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

33 CanmetENERGY Study: The Combustion Characteristics of Charcoal and a Strategy for the Development of Biocoal Formulations for use in Utility Boilers The objectives of this study were to investigate: The combustion characteristics of commercial charcoal and determine how it would behave in a utility boiler. Determine if there exists more optimal charcoal formulations for use in utility boilers Acknowledgements: R. Dureau, B. Clements, A. Palmer, L. Giroux

34 Hardgrove Index Charcoal Eastern HVBit Alberta Sub C Rocky Mountain MVB HGI

35 Ignition Temperature Charcoal Eastern HVBit Alberta Sub C Rocky Mountain MVB Ignition Temperature ( o C)

36 Comparative Proximate Analysis Wt% Moisture Wt% Ash Wt% Volatile Matter Wt% Fixed Carbon 32.1 Biocoal # MJ/kg HHV Rocky Mountain MVB Alberta Sub C Eastern HVBit Wood Units

37 Comparative Ultimate Analysis Wt% O Wt% S Wt% C Wt% H Wt% N Wt% Ash 3.13 Biocoal # Wt% Moisture Rocky Mountain MVB Alberta Sub C Eastern HVBit Wood Units

38 Comparative Ash Analysis Units Biocoal #1 Eastern HVBit Alberta Sub C Rocky Mountain MVB SiO2 Wt% Al2O3 Wt% Fe2O3 Wt% CaO Wt% Na2O Wt% K2O Wt% MgO Wt% TiO2 Wt% SO3 Wt% P2O5 Wt% 5.23 Na Na Na BaO Wt% 0.28 Na Na Na SrO Wt% Na Na Na Ash Issues Require Further Study

39 Energy Density Charcoal 9-11 GJ/m3 Wood 8-10 GJ/m3 Coal GJ/m3 Energy density is still an issue as volume of fuel becomes a limiting factor for existing feed systems

40 Future Directions for Char Energy Torrefaction Char-Oil Slurries Charcoal Pellets Charcoal Gasification

41 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 >700ºC Gasification H2, CO IN

42 Torrefaction As is the case for charcoal Torrefied wood pulverizes easily Heating value is MJ/kg (vs for wood) Energy density is GJ/m3 (vs 8-10 for wood) Torrefaction yield > 80% Dry fuel Does not absorb water Water-proof high energy pellets?

43 Char-oil Slurries Energy Density GJ/m3

44 Pelletizing Charcoal?

45 Charcoal Gasification Charcoal produces cleaner syngas than wood

46 Thank You! Questions? Fernando Preto Tel: