Determination of Volatile Organic Compounds Emitted From

Softwood Pellets During Storage

Mehrdad Arshadi,Unit of Biomass Technology &

Chemistry

Fuel pellets as an energy resource

Mehrdad Arshadi,Unit of Biomass Technology &

Chemistry

Bio-fuel Classification

Wood Fuels Agro Fuels

Solid Liquid LiquidSolid

Chips, Sawdust,

Charcoal, Briquettes, Pellets

Black Liquor, EthanolMethanol, Pyrolytic Oil

Straw, Stalks, Briquettes,

Powder, Pellets

Raw Vegetable Oil,Bio-Diesel, Methanol,

Ethanol,

Biogas

GasesGases

Wood pellets• Made of sawdust• Mainly of pine and spruce • Energy resource for heating

houses and some industries

• Renewable • Today 30 wood pellets

productions companies producing about 1400 000 tons of pellets per year in Sweden (price 188-248 Euro/ton)

Fuel pellets can be made of:• Sawdust,• Bark,• Reed canary grass• Cotton,• Cutter shaving • Olive oil seeds• Eucalyptus leaves• Rape seed cakes• Peat• Salix (Willow) • etc

Different kind of pellets

Salix

Cotton plant (bushes)

Eucalyptus leaves

Olive seeds

Hungarian grass

Reed canary grass

Different kind of pellets, cont.

Peat,10 mm

Peat,6 mm

Cotton residue,leaves & flowers

Cotton seed residueafter pressed oil

Hemp

Wood,pine/spruce

Wheat straw Bark (pine) Bark (spruce)

Different kind of pellets, cont.

Bio-Fuel Technology Centre

Dosage screw

Silo

Mixing screw

Air separator for metal, gravel reduction

Fan

Cyclone

Bale moving belt

Course mill (shredder)

Fine mill

Pellets press Mixing screw

Bio-Fuel Technology Centre (BTC), a pilot plant for pellets production

Metal & gravel material

Fan

Cyclone Air separationtable

material + Air

Air

Input Screw

Material+ air

Material out

Shaking table

Air separator & Cyclone

DryerMixer/balance

Pellet press

Pellet cooler

Mill

Conveyor

Steam generator

Bio-Fuel Technology Centre (BTC), the second line

Why using wood pellets and not sawdust directly?

• Lower moisture content (no risk for mould formation)

• Low transport costs• Higher energy content per volume• Easy to feed in burners• Low storage costs• Higher density and better combustion• Homogeneity, less variations in moisture

content

Pellets compared to other FuelsAdvantages with pellets Disadvantages with

pelletsOil Renewable Needs larger storage place

Domestic production New, needs for establishment

Cheaper Ashes

Electricity Cheaper Need for storage room

Electricity can be used in more important aspects Ashes

New marketing

Emissions

Wood Less work with production More expensive fuel

Higher energy density

Automatic feed of the fuel to burner

Smaller equipment needs with combustion

Easier to transport

Usage of pellets as fuel

• Household sector• Industrial sector• Heat and power generation• Heating government official building

like hospitals, schools, etc• Other commercial sectors• Transport of raw material for ethanol

production from cellulose (wood)

Energy content (Net calorific heat values MJ/kg Dry Substances)

• Reed canary grass 17.2 • Straw 17.4 • Willow 18.3 • Sawdust 19.2• Wood Pellets 19.2 • Wood 19.2• Peat 21.5• Coal 27.2• Oil 42.7

Development of Swedish Pellet Market (energy production)

0

1

2

3

4

5

6

1997 1998 1999 2000 2001 2002 2003

Pelle

t del

iver

ies

(TW

h)

Swedish Pellet Market Development

• 2003 1,1 million tons• 2004 1,2 million tons• 2005 1,4 million tons• 2006 1,7 million tons• 2007 2,0 million tons• 2008 2,3 million tons

Prognosis

Source: The bio-energy

international

Source: The bio-energy

international

Source: The bio-energy

international

Pellets production in Denmark

Source: The bio-energy

international

Other raw material such as reed canary grass

Pellets Production

• Small Scale, productions capacity around 500 kg of pellets per hour (4000 tons/year).

• Medium Scale, productions capacity 5 000-50 000 tons/year.

• Large scale, productions capacity more than 50 000 tons/year. Sometimes heat & power at the same time.

The Commercial pellet Mills• SCA BioNorr AB in

Härnösand, 150 000 tons/year

• Skellefteå Kraft AB, 90 000-115 000 tons/year

• Bioenergi i Luleå AB,120 000 tons/year

Fuel pellets properties

• Length (mm) • Moisture content (%) • Ash content (% dry wt)• Calorific value (MJ/kg dry wt)• Density (kg/m3)• Durability (%)• Particle size distribution in raw material (%wt)

One example of technical data for pellets

• Moisture content is about 6-8 %• Energy value in 1 ton of pellets is about 5.0

MWh, which is about 0.5 m3 oil• 1 m3 oil = 2 tons pellets = 3.16 m3 pellets• Bulk density (Weight) = 630 kg per m3

• Individual density = 1200 kg per m3

• Dimension: 6 or 8 mm i diameterLength: 5 — 15 mm.

• No binding or other additives used in Sweden• Ashes: about 0.3 % of weight

Sieving

Wood Pellets process

Sawdust Drying Grinding

Pressing

CoolingSievingStoring

Sieving Pellets

Wood pellets process

• Drying of wet sawdust (~ 45-55 % water) to 5-15 % moisture content, requires a lot of energy,

• Grinding to particle size < 3 mm,• Pressed through cylindrical holes in a

pellets matrix, temperature rise to above 100 °C,

• Cooling the pellets & storage

Sawdust

Pressing of pellets

Matrix & die

Sieving

Pellets transport

• Pellets in bulk by boat, train and lorry

• Pellets in large sacks (600 kg)

• Pellets in small sacks (16 kg)

Burner (Eco Tec 30 kW)

Burning of pellets

Boilers for ash rich pellets

Welcome to Umeå and Vasa and enjoy the nearly continuous 24 hour sunlight!

NIR 2007

Spreading the Light

•Spectroscopy•Chemometrics•Sampling / Sample Presentation•Imaging•Process / Online•Food / Feed•PAT•Frontier / Emerging New Instruments

13th International Conference Near Infrared Spectroscopy 15-21 June 2007 Vasa, Finland & Umeå Sweden