Will different production processes influence the off ... · flat die pellet mill ring die pellet mill Pellets 2018, 30 –31 January 2018, Helsingborg, Sweden. ... combined in one

Will different production processesinfluence the off-gassing and self-ignition

behaviour of wood pellets?

Prof. Dr. Werner Sitzmann

Amandus Kahl GmbH & Co. KGReinbek, Germany

Pellets 2018, 30 – 31 January 2018, Helsingborg, Sweden

Contents

- Kahl-Group

- Energy saving pan grinder mill

- How to influence autoxidation

- Conclusions


Green coffee

warehousing and

processing centre

Coffee roasting

plants

Roasting technology

for nuts and kernels

Particle technology

Recycling industry

(tyres, waste, sludge,

biomass and wood)

Chemical industry

Food and sugar

industry

Feed industry

Petfood industry

Edible oil industry

Rice and grain

processing industry

(cereals, legumes)

Edible oil industry

Hydrothermal

treatment

Spice and tea

processing industry

Systems for the

food industry:

Pasteurisation

Fermentation

Cooling

Freezing

KAHL - Group

Each company of the KAHL - Group has been successful in its own markets and offers worldwide solutions, plants and machines for the following industries:



Facility – Amandus Kahl

A Global Player

AMANDUS KAHL

Reinbek/Hamburg,

Germany

Moscow, Russia

Amman, Jordan

AMANDUS KAHL

Ibérica

AMANDUS KAHL

Benelux

AMANDUS KAHL

France

AMANDUS KAHL

USA Corp., USA

HEINEN Freezing

Varel,

Germany

NEUHAUS NEOTEC

Ganderkesee,

Germany

SCHULE

Reinbek/Hamburg,

Germany

AGENCYCOMPANY SUBSIDIARY

Cairo, Egypt

Kuala Lumpur, Malaysia

10 x 6 mt/h pine – USA (Enviva)


Jan. 2018: New machine type 65-1500: ~ 7 mt/h

Two types of pelletizers

material

flat die pellet mill ring die pellet mill


Product inlet

Product distribution

Adjusting nut for roller gap, hydraulic

Flexible ring

Pan grinder roller

Pan grinder head

Scraper

DieCutting device

Main shaft

Design and functionof the flat die pelletingpress



Wood chips

Wet grinding

Drying

Dry grinding

Pelleting

- Domestic fuel

- Industrial pellets- Pellet post-grinding

(dust firing in power plant)

Wood pellet production from wood chips

Shearing and cutting forces

combined in one system

Pan grinder mill

Hammer mill

Hitting forces by hammers.



Wet grinding using the pan grinder mill

Shearing and cutting effect due to the

variation of pan grinder rollers (width,

surface, diameter) and die (shape, depth

and arrangement of holes)


predetermined

breaking points

Hammermill (left) and pan grinder mill (right) ground

wood chips


Energy-minimised production of wood pellets

Hammer mill

Hammer mill Pan grinder mill

0 50 100

particle

size

reduction

0 50 100

%%

b) wet grinding with pan grinder mill

dry grinding with hammermill

a) wet and dry grinding with

hammermill

specific energy input, %

hammermill pan grinder mill

dry grinding step

components

celluloses

phenolicingredients

polysaccha-

spruce pine larch

cellulose 42.5 42.1 40.1hemi-

23.1 21.8 23.2

lignin 28.4 28.3 29.1extractivematters

3.2 6.7 4.5

resins,waxes, fats

1.2 4.9 1.2

rides

2.0 1.8 3.3

sawdust

Chemical composition of different wood types, weight - %



Landesinstitut f. Schulentwicklung, Baden-Württemberg

fat = triglycerideFatty acid (FA)

FA radical

FA peroxide radical

FA hydroperoxide

Aldehyde formation

Hexanal as main

product

Alcohols, ketones, CO -

formation etc. etc.

Structural formula of fat & autoxidation of fatty acids

Fatty acid (FA)

= unsaturated binding

Chain forming

radical


Autoxidation of fats and oils …

… is a very complex, exothermal chain reaction that requires

- oxygen

- radicals (caused by H2O2 for example)

- unsaturated chemical bindings

- time

- temperature (heat)

… is found by different research groups to be the main

reason for off-gassing and self-ignition of wood pellets !


Kinetics of autoxidation of fats/oils

start of rancidity

peroxides

volatiles

time

degree

of

oxidation

O2 binding

hexanal

Induction

phase

Heiss, Eichner: Haltbarmachen von Lebensmitteln, 1990


Thesis of this study

Will it be possible to influence autoxidation during pellet production by

- changing the grinding processes (surfaces, mass transfer),

- adding radicals (increasing the reaction rate) and/or

- increasing residence time by increasing the storage period between dry

grinding and pelleting after radical-addition?

Target: Autoxidize defined as many as possible of wood containing unsaturated

chemical compounds during the pellet production process to prevent off-

gassing and self-ignition later on !

Forming of hexanal characterizes the degree of autoxidation


start of rancidity

peroxides

volatiles

time

degree

of

oxidation

O2 binding

hexanal

Target: Acceleration of autoxidation

Heiss, Eichner: Haltbarmachen von Lebensmitteln, 1990


Wood chips

Wet grinding

Drying

Dry grinding

Pelleting

- Domestic fuel

- Industrial pellets- Pellet post-grinding

(dust firing in power plant)

Wood pellet production from wood chips

hammermill OR pan grinder mill

H2O2 as

radical donator

+ time

hammermill OR pan grinder mill


Analytics

Prüfverfahren µ-Chamber

• Small samples (up to 6 in parallel) • Bulk-/Cell-mode• Temperature:

• RT ... 120 °C

• Air Flow:• 10 ... 500 mL min-1

• Adsorption tubes with Tenax®-TA

• Analysis by TD-GC-MS

Dr. Ohlmeyer, v. Thünen – Institut, Hamburg

Significant different autoxidation behaviour

0

1000

2000

3000

4000

5000

Hex

anal

[µg/kg/h]

23.01.2018

All parameter combinations

0

1000

2000

3000

4000

5000

Hex

anal

[µg/kg/h]

23.01.2018

Emission rate

of hexanal

per 1 kg of pellets

Influence of grinding process

Pan grinder mill Hammer mill

0

1000

2000

3000

4000

5000

Hexanal [µ

g/k

g/h

]

23.01.2018

Influence of H2O2 – addition in the conditioner

Emission rate

of hexanal after

per 1 kg of pellets

H2O2

H2O

0

1000

2000

3000

4000

5000

Hex

anal

[µg/kg/h]

23.01.2018

Influence of residence time after H2O2 - addition

Emission rate of hexanal

(four hours reaction time after

conditioning) per 1 kg of pellets

time

Conclusions


First qualitative studies showed that autoxidation can be

influenced by

- changing the grinding process

- increasing the reaction rate by adding radicals

- applying additional residence times during pellet

production after addition of radicals

„Make autoxidation happen within the pellet production

line!“


Thank you very much !


Documents

Will different production processes influence the off ... · flat die pellet mill ring die pellet mill Pellets 2018, 30 –31 January 2018, Helsingborg, Sweden. ... combined in one