Common reed as solid Common reed as solid biofuelbiofuelresourceresource

ĒĒ.. KronbergsKronbergs and and AA.. KronbergsKronbergs

Latvia University of AgricultureLatvia University of AgricultureFaculty of EngineeringFaculty of EngineeringInstitute of MechanicsInstitute of Mechanics

11.03.2011.

Ludzasraj.

Rèzeknes

raj.

Daugavpils

raj.

Krâslavas raj.

Latvian more than 2256 Lakes with sapropel(sediment ) resources

Investigated resources

2

Common reeds (Phragmites australis) are overgrowing shorelines of Latvian Lakes –important resource for bioenergy

Phragmites australis

Photo I. Nulle3

The evolution of Lakes and wetlands (Sven Bjork)

Sediments and emergent vegetation transform Lakes to bog ecosystem

4

The Lake restoration project – common reed cutting

5

The Lake restoration project – common reed root felt cultivation

6

Cable operated bucket (6 m3) equipment for sapropel mining. Used also for common reed root felt removal

7

Soft container method

8

Ecosystem approach let work out innovative mechanisation means in Laboratory of mechanics of LUA and obtain

additional biomass resources

9

Ultimate tensile strenght – 330 N/mm2

Ultimate shear strenght – 110 N/mm2

Specific shear cutting energy –0.024 J/mm2

Nip angle – 23 deg

Calorific value – 17 .. 19 MJ/kg

Bulk density – up to 100 kg/m3

Mechanical properties of reed stalks

10

Materials testing machine

ZwickTC-FR2.5TN.D09 TestXpert V9.01

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Compacting of common reed particles

Reed particles were compacted in closed die D=35 mm with pressure 212 MPa using hydraulic press equipment 12

Compacting of common reed particles

In compacting the minimum of density 0.87 g cm-3 have briquettes with particle size 12 – 13 mm, but maximum density 1.03 – 1.04 g cm-3 have briquettes of two particle sizes – less than 0.5 mm and size 32 – 33 mm.

< 0.5 mm

12 – 13 mm

32 – 33 mm

13

Compacting of common reed particles

Specific pressing energy maximum value (~172 kJ kg-1) has been for reed particle size 32 – 33 mm, but minimum value (~53 kJ kg-1) for particle size less than 0.5 mm 14

Long reed stalk particle 300 mm briguetting and strength testing

Arranged structure of biomass particles in briquetting is increasing durability of briquettes and let obtain density >1000 kg·m-3. Increasing peat proportion in arranged structure reed briquettes till 50% increases splitting force 2 – 3 times. 15

Cutting equipmentCutting equipment

Fig.1. Cutting knives with different geometry Fig.2. Cutting knives

Fig.3. Cutting knive

0.007

0.009

0.011

0.013

0.015

0.017

0 5 10 15 20 25Blade angle, deg

Spac

ific

ener

gy, J

mm

-2

Bevel angle 90ºBevel angle 45ºBevel angle 25º

Fig.4. Specific cutting energy for flattened reed stalks. 16

Cutting properties in dependence on cutter mechanism

Cutting mechanism

№ 1 № 2 № 3 № 4 № 5

τmax,

N mm-2

E,

J mm-2

τmax,

N mm-2

E,

J mm-2

τmax,

N mm-2

E,

J mm-2

τmax,

N mm-2

E,

J mm-2

τmax,

N mm-2

E,

J mm-2

43.6 0.028 24.1 0.024 13.1 0.037 19.0 0.028 16.1 0.052

The cutting knives mechanism № 2 is approved as the most energy efficient.

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Energy crop stalk material cutting energy

Specific cutting energy per mass unit is growing considerably when shredding size is less than 20 mm for common reeds and 35 mm forhemp stalk material. 18

BiomassBiomass shreddershredder

Properties:Properties:

Material Material –– common reedcommon reedKnives thickness Knives thickness –– 8 mm8 mmFraction Fraction –– 1 .. 1 .. 4 cm4 cmShredded reed bulk density Shredded reed bulk density –– 135 kg/m135 kg/m33

Briquette density Briquette density –– 1.04 g/cm1.04 g/cm33

Fig.2. Shredded common reedFig.1. Shredder

Fig.3. Common reed briquette 19

Evaluation of energy crop shredder unification possibilities

Fig.1. Shredder Tuennissen GM-10

Fig.2. Cutting knives and flywheel

The rounding in cutting knives are increasing nip angle.

Increased nip angle improve the biomass shredder technical parameters by reducing rotation speed deviation and wear of cutting and counter knives.

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Thank you for your attention!

Latvia University of AgricultureFaculty of EngineeringInstitute of Mechanics

Prof. Ēriks Kronbergseriks.kronbergs@llu.lv

Andris Kronbergsandris.kronbergs@llu.lv