Pyrolysis for Biochar Production

Transcription

1 Pyrolysis for Biochar Production Ondřej Mašek Peter Brownsort, Juan Turrion Gomez, Kyle Crombie, Saran Sohi, Andrew Cross, Simon Shackley University of Edinburgh Ondřej Mašek, Nordic Biochar Workshop, Oslo, Norway, 10 th November, 2011

2 The pyrolysis-biochar system (PBS)? CO 2 6 Gt y -1 photosynthesis biomass C soil C 60 Gt y -1? fossil fossil carbon C (energy) pyrolysis biochar C

3 What is pyrolysis Process occurring in all thermochemical conversion processes of organic materials (combustion, gasification, pyrolysis)

4 Types of pyrolysis Fast pyrolysis Slow pyrolysis

5 Biochar production - Carbon rich product of biomass pyrolysis - Can take many forms and have different properties Traditional charcoal burning air smoke char Batch pyrolysis kiln char oil, tar, liquids Industrial unit for continuous production char gas, oil, tar

6 Pyrolysis Which parameters matter Feedstock related - particle size and shape - physical properties (e.g., density) - composition (lignin, cellulose, etc.) - ash content and composition - Process related - peak temperature - pressure - heating rate - residence time - heat transfer - vapour/ solid interaction -

7 Challenges Operation - material feeding - exclusion of O 2 - tar condensation - blockage - corrosion Control - temperature measurement - gas flow rate measurement - particle temperature history Use of co-products - low ph of pyrolysis liquids - low heating value - high water and oxygen content

8 Operational challenges

9 Process control Temperature measurement - Where? (gas phase, particle bed, ) - How? (aggressive environment, difficult access, ) thermocouple 550 C optical (IR, etc.) 550 C? Complicated by the presence of gases and vapours from pyrolysis

10 Use of by-products Steam turbine Stirling engine Combustion turbine IC engine Upgrading - physical (removal of particulates, condensables and water) - chemical (removal of contaminants, improved CV, stability, composition, etc.)

11 Pyrolysis research at the UK Biochar Research Centre (UKBRC)

12 UK Biochar Research Centre UKBRC November 2010

13 UKBRC development of predictable biochar Strategy & recruitment Facilities bidding and implementation Biochar assessment toolkit (for soil function) Multivariate analysis for random samples Identify relevant functions and contexts Systematic sets of biochar (and biochar assessment) Testing context-specific selection in the field Late 2008 about now Late 2013 Bespoke biochar Concept established New tools and better data at some scale viable?

14 UKBRC - Pyrolysis UKBRC official opening April 2009 Lab-scale batch pyrolysis: 30 g / day Feb Stage 1 Dedicated biochar laboratories Jul Lab-scale slow pyrolysis (continuous flow): 1.5 kg / hr Jan Pilot-scale slow pyrolysis (continuous flow): 20 kg / hr May Stage 2 Stage 3

15 Pilot-scale biochar production facility Afterburner Cooling screw Feed hopper Discharge chute Rotary kiln Feed screw

16 yield [wt. %] Biochar yield The yield of biochar decreases with increasing temperature The yield of biochar decreases with increasing heating rate The yield of biochar is higher in batch reactor without sweep gas temperature [C] FW 5 FW 100

17 The Edinburgh screening toolkit for biochar A toolkit for rapid comparison of short-listed biochar products Emphasizes soil functional attributes Tool A: Labile carbon Tool B: Stable carbon Tool E: SOM priming Tool C: Nutrient value Tool D: Soil structural impacts Expandable (e.g. to elements of risk)

18 Biochar stability In terms of stability, biochar consists of three fractions: Labile fraction that disappears in a short period (weeks) Intermediate fraction that is removed on the scale of months to years Stable fraction that is retained over very long time (centuries) How do we know how much biochar remains after one or more centuries? Accelerated oxidative ageing procedure (photo / thermal / chemical) to quantify stable carbon - calibrated using XPS

19 stable fraction [%C] Biochar stability The stable carbon fraction in biochar increases with temperature The stable carbon fraction in biochar shows only small dependence on heating rate temperature [C] FW 5 FW 100

20 stable C yield [wt. %] Biochar stability The yield of stable carbon fraction in biochar increases with temperature The yield of stable carbon fraction in biochar decreases with increasing heating rate temperature [C] FW 5 FW 100

21 Stable C Yield (%) Biochar stability The yield of stable carbon fraction in biochar increases with temperature The yield of stable carbon fraction in biochar decreases with increasing heating rate Stabe C yield [wt.%] (dry feedstock basis) FW FW - 5 rice husk rice husk - 5 Pine Temperature ( o C)

22 Bespoke biochar Biochar produced to exact specifications for a specific purpose as determined by its functional properties. Specified biochar Biochar produced to exact specifications.

23 Pyrolysis research areas of work Specified biochar development The aim is to develop understanding of how feedstock and production conditions influence functional properties of biochar in respect to the purpose of its application. Contaminant issues Study of the formation and fate of contaminants in the pyrolysis process and their environmental availability. Process modelling Modelling of the flow of material and energy in pilot-scale pyrolysis unit with the aim to tune and optimise the process for specified biochar production. Modelling of pyrolysis Development of chemical models of the pyrolysis process with special focus on pyrolysis of waste materials. Value added products Study of the potential to develop value added products from liquid and gaseous co-products of pyrolysis.

24 CHARCHIVE - Global distributed repository of (physical) biochar samples and data - Web-based database available to research partners - Systematic collection of samples and their characteristics - Serve as a reference for the biochar research community.

25 THANK YOU!