Influence of nature of biomass on grindability after torrefaction

(1)

Influence of nature of biomass

on grindability after torrefaction

A.Leboeuf

1

, J-M. Commandré

1

, P. Rousset

1

,

C. Dupont

2

,

C. Verne-Tournon

2

, D. Da Silva Perez

3

, F. Labalette

4

1

CIRAD, UPR42 Biomasse Energie, TA 10/16, 73 Rue J-F. Breton, 34398 Montpellier Cedex 5, France

2

Commissariat à l’Energie Atomique et aux Energies Alternatives, 17 rue des Martyrs, 38054 Grenoble cedex 09, France

3

FCBA, 24, rue Joseph Fourier, 38400 Saint-Martin-d'Hères, France

4

GIE Onidol - Arvalis, 12 avenue Georges V, 75008 Paris, France

E-mail : alexandre.leboeuf@cirad.fr & jean-michel.commandre@cirad.fr

Horizontal Tubular Reactor (HTR)

Introduction - Context

High temperature gasification of biomass is one of the most promising technologies to produce synfuels or H₂. These operating conditions requires a fine grinding of biomass, which is energy costly. Biomass torrefaction is a pre-treatment

process allowing to reduce grinding energy consumption.

Interest of our work: Grindability of torrefied solids after torrefaction depend on operating conditions and nature of biomass.

Objective of this study: Characterisation of energy required for grinding before and after torrefaction of 4 types of biomass : softwood, short rotation coppice poplar, agricultural residue and perennial feedstock.

• Torrefied biomass at different temperatures

with similar weight loss (≈17 %) in HTR

• Same grinding protocol (residence time,

volume of sample)

Results

Conclusions

• Torrefaction pretreatment reduces particle size distribution and grinding energy consumption .

• Except for wheat straw, particule size distribution is similar whatever nature of biomass or thermal

pretreatment

• Torrefaction gathers grinding energy distributions of different biomasses.

• Future works: Determine grinding energy consumption after torrefaction at different weight losses

Experimental

Short rotation coppice poplar

Pine Miscanthus Wheat straw Ball mill V er ti ca l o sc il la ti o n Assumptions:

• Relative energy before grinding = 1

• Shape of particles after grinding: sphere

• Energy proportional to the surface created

1 10 100 10 100 1000 R e la ti v e g ri n d in g e n e rg y ( -) dp(µm) Raw Poplar Raw Miscanthus Raw Pine

Raw Wheat straw Torrefied Poplar Torrefied Miscanthus Torrefied Pine

Torrefied Wheat straw

Short rotation coppice poplar

Raw Torrefied Pine Raw Torrefied Miscanthus Raw Torrefied Wheat straw Raw Torrefied 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 10 100 1000 G ra n u lo m e tr ic d is tr ib u ti o n ( % ) dp (µm) Raw Poplar Raw Miscanthus Raw Pine

Torrefied Wheat straw

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 10 100 1000 C u m u la te g ra n u lo m e tr ic d is tr ib u ti o n ( % ) dp (µm) Raw Poplar Raw Miscanthus Raw Pine