biochar tecnologia

biochar tecnologia

(Parte 2 de 3)

Constant heating rate (10°C/min) with N (9.995%) sweep gas at 120 ml/min

Yang, H., Yan, R., Chen, H., Lee, D. H., and Zheng, C. (2007) Characteristics ofhemicellulose, cellulose and lignin pyrolysis Fuel 86, 1781-1788.

Reaction pathways for cellulose dec omposition

Mok, W. S. L.; Antal, M. J. Effects of Pressure on Biomass Pyrolysis. I. Heats of Reaction of Cellulose Pyrolysis. Thermochim. Acta1983, 68, 165.

Effect of reaction pressure and diluent gas flow on char production

Mok, W. S. L.; Antal, M. J. Effects of Pressure on Biomass Pyrolysis. I. Heats of Reaction of Cellulose Pyrolysis. Thermochim. Acta1983, 68, 165.

endothermic exothermic

Secondary Charcoal Generation Secondary Charcoal Generation

Some specific goals for advanced biochar manufacture

•Continuous feed pyrolyzersto improve energy efficiency and reduce pollution emissions associated with batch kilns

•Exothermic operation without air infiltration to improve energy efficiency and biochar yields

•Recovery of co‐products to reduce pollution emissions and improve process economics

•Control of operating conditions to improve biochar properties and allow changes in co‐product yields

•Feedstock flexibility allowing both woody and herbaceous biomass to be converted to biochar

Concepts for Advanced Charcoal Kilns

•Slow pyrolyzers (drum pyrolyzer, rotary kiln) •Flash carbonizer

•Fast pyrolyzers (fluid bed, screw reactor, en tr ained)

•Biomass gasifiers (fluid bed, downdraft)

•Hydrothermal processing reactors

•Wood‐gas stoves

Preliminary Studies to Compare Chars from Different Thermal Processes

Pr ocess Air filtr ation Hea t Sour ce Temper atur e Time

Slow py rolysis NoneExternal500 C30 minutes

Fast py rolysis NoneExternal500 CFew seconds

Gasification20% equivalence ra tio

Combustionof infiltrated air 750 CFewminutes

Scanning Electron Micrographs S wit chgr ass Feeds tock

Gasification Char Slow Pyrolysis Char

Fast Pyrolysis Char

Effect of Feedstock and Thermal Process on Char Properties

Feeds tock Pr ocess Higher Hea ting Value (kJ/kg)

BET Surface Area

(m 2 /g )

Corn StoverSlow Pyrolysis21,5964.1

S wit chgr ass Slow Pyroly sis 12,799 2.8

Corn StoverFast Pyrolysis13,8334.5

S wit chgr ass Fas t Pyr oly sis 16,337 17.7

Corn St over Gasific ation 15,290 43.6 S wit chgr ass Gasific ation 15,864 39.2

Fourier Transform Spectra of Feedstock and Resulting Chars

Corn Stover Feedstock & Char

Wavenumber (cm-1 )

Corn Stover Feedstock

Slow Pyrolysis Char Fast Pyrolysis Char

Gasification Char

CationExchange Capacity (CEC) of Chars

Feeds tock Process React or type CE C (cmol/kg) Corn stoverFast pyrolysisPDU fluidized bed29.89 Switchgrass Fast pyrolysisPDU fluidized bed16.3 Loblolly pineFast pyrolysisLab scale fluidized bed14.21 Corn stoverFast pyrolysisLab scale free fall reactor12.23 Switchgrass Gasification PDU fluidized bed11.34 Corn stover Gasification (cyclone 1) PDU fluidized bed31.4

Corn stoverGasification (cyclone 2) PDU fluidized bed17.21 Hardwood Slow pyrolysisLab scale fixed bed19.04

Switchgrass Slow pyrolysisLab scale fixed bed12.35 Woodw aste Gasific ation Lar ge pilot ‐sc ale 12.1

Used modified Compulsive Exchange Method (Gilman & Sumpter1986, Laird & Fleming 2008)

Conclusions

(Parte 2 de 3)

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