biochar tecnologia

biochar tecnologia

(Parte 1 de 3)

Biochar Production Technology

Robert C. Brown

Center for Sustainable Environmental Technologies

Department of Mechanical Engineering Iowa State University

Purported Properties of Biochar

•High soil organic matter

•Enhanced cationexchange capacity (nutrient holding capacity)

•Improved water retention

•Beneficial soil microbial activity

•Enhanced fertility

•Stable (“aromatic”) carbon structure

Carbon Stored

Pyrolytic CharNo-Till SwitchgrassNo-Till CornPlow-Tilled Corn

Greenhouse gases reduction by carbon storage in agricultural soils

Char from pyrolyzing one-half of corn stover

Pit kilnMound kiln Traditional Charcoal Making

Brick kiln TPI* transportable metal kiln

*Tropical Products Institute

Traditional Charcoal Making

Missouri‐type charcoal kiln

Continuous multiple hearth kiln

Traditional Charcoal Making

Kiln TypeCharcoal Yield*

(%) Pit 12.5-30

Mound 2-42

Brick 12.5-3

Portable Steel (TPI)18.9-31.4 Concrete (Missouri) 3

Charcoal yields (dry weight basis) for different kinds of batch kilns

Kammen, D. M., and Lew, D. J. (2005) Review of technologies for the production and use of charcoal, Renewable and Appropriate Energy Laboratory, Berkeley University, March 1, http://rael.berkeley .edu/files/ 2005/Kammen-Lew-Charcoal-2005.pd f, accessed November 17, 2007.

*η char

= (mchar/mbio ) x100

Charcoal Yield Corrected for Ash Content of Biomass ηfc = (mchar/mbio)[cfc /(1 ‐ba )] x 100 wher e:

m char = dry mass of charcoal from the kiln mbio = dry mass of biomass loaded into the kiln c fc = fixed C content of biochar as measured by

ASTM Standard D 1762‐84 b a = ash content of the dry biomass

Charcoal yield on the basis of ash‐free organic mass into ash‐ free carbon is calculated according to:

A perfect kiln would have fixed‐C yield equal to the solid C yield predicted by thermodynamic equilibrium. For example, the pyrolysis of cellulose at 400°C and 1 MPashould have a fixed‐C yield of 27.7%.

Air emissions per kilogram biomass from different kinds of charcoal kilns

CH 4



1 NMHC –non‐methane hydrocarbons (includes recoverable methanol and acetic acid)

2 TSP –total suspended particulates

Shafizadeh, Fred, 1982, Chemistry of pyrolysis and combustion of wood, in Sarkanen, K.V., Tillman, D.A., and Jahns, E.C., eds., Progress in biomass conversion: London, Academic Press, p. 51–76.

Typical product yields (dry basis) for different modes of pyrolysis

Mode Conditions Liquid Char Gas

Fast Moderate temperature ~ 500°C short vapor residence time ~ 1 s 75% 12% 13%

Moderate moderate temperature ~ 500°C moderate vapor residence time ~ 10-20 s

Slow moderate temperature ~ 500°C very long vapor residence time ~ 5- 30 min

Gasification high temperature > 750°C moderate vapor residence time ~ 10-20 s

Thermogravimetricanalysis of the pyrolysis of plant components

(Parte 1 de 3)