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Green Energy from wood or torrefied wood?
A Multi Disciplinary Project 2 September 15
November
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Green Energy from wood or torrefied wood?

• Paul Gevers ( Project leader) TN
• Astrid Frehen ST
• Bram Taks TEMA
• Edwin van Steen ST
• Giel Ramaekers WTB
• Jordy Sturms ST
• Marvin Sijbinga ST
• Jeroen van Duren Tutor

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Assignment

• Green energy is a hot topic.
• One of the possibilities is biomass gasification.
• When importing biomass, transport is an expensive
  part.
• Torrefaction is a chemical process to treat
  biomass.
• Investigate the chain of forest via import to
  electricity. Make a comparison between wood and
  torrefied wood.

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Restrictions

• Production of wood in Russia.
• Torrefaction of wood in neighbourhood of
  production.
• Gasification of (torrefied) wood in Amer-9 Power
  plant.
• Scale size is related to maximum output of
  current gasifier.

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Plan (subjects)

1. Chemistry / Technology
2. Law / Politics
3. Social acceptance
4. Environment / Sustainability
5. Economics

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Plan (processes)
Forest
Torrefaction
Transport
Transport
Gasification
Gas turbine
Combustion
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Forestry

• Location St. Petersburg area.
• Good Infrastructure.
• Forestry industry.
• Climate.
• Distance.

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Politics (main conclusions)

• The Netherlands has goals to increase green
  energy.
• Financial support has decreased.
• Certified sustainable forestry (FSC) is
  preferable.
• Russia has goals to increase economics.
• No import or export limitations.

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Social acceptance (main conclusions)

• The general public is sceptical towards biomass
  as sustainable energy source, because of lack of
  knowledge.
• The public sees energy from biomass as less
  "green" than wind and solar energy.
• Attitude toward transport of biomass in
  uncertain, but transport will be hard to explain.
• If imported wood is used, it has to be certified
  (FSC).

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Introduction to Torrefaction

• Torrefaction is mild pyrolysis pyrolysis at
  relatively low temperatures.
• Processes that take place are
• Thermal processing of biomass (cracking).
• Low quantities of oxygen supplied oxidation
  takes place in small amounts.
• Water is evaporated.

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Introduction to Torrefied Wood process

• Approximate temperature range
• Below 200C endothermic reactions, no
  combustible products, dehydration of wood.
• Between 200C and 280C endothermic reactions,
  combustible products are formed.
• Above 280C exothermic reactions, combustible
  products are formed.

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Introduction to Torrefied Wood properties

• Properties of wood after torrefication
• Hydrophobic.
• Friable.
• Lower moisture content than raw wood (mass).
• Higher specific caloric value than raw wood
  (MJ/kg).
• All results are on Lab-scale!

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Results earlier experiments moisture content
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Correlation of Milne for HHV

• Computation of the HHV by the correlation of
  Milne
• Percentages are moisture, and ash free must be
  corrected for moisture and ash.
• Conclusion high weight percentages of carbon and
  hydrogen lead to high values for the HHV.

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Results earlier experiments composition, carbon
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Results earlier experiments composition, oxygen
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Results earlier experiments composition, hydrogen
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Balance of enthalpy computation HHV

• As the carbon and hydrogen content increase while
  the oxygen content approximately decreases as
  much as the carbon content increases, the HHV
  will increase according to the correlation of
  Milne.

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Balance of enthalpy results computation HHV
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Balance of enthalpy computation ?H
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Balance of enthalpy results computation ?H

• ?H gt 0 Endothermic process
• ?H lt 0 Exothermic process
• If there is no temperature control ?H has to be
  larger than zero to prevent thermal runaway. At
  high temperatures the wood is gasified instead of
  torrefied.

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Torrefaction Reactor

• We thought about a rotary tube reactor
• The rotating of the tubes homogenizes the
  temperature in the reactor.
• This effect is improved by supplying the
  superheated steam flow that heats the wood
  through to rotating tubes.

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Gasifier

• Amer-9 fluid-bed gasifier with Lurgi gas
  cleaning.
• By blowing large quantities of gas through the
  gasifier the bed of wood chips of hovered. This
  implies a large reactive surface and good heat
  transfer. Additives can be inserted.
• The syn-gas passes a cyclone which separates
  solid particles from the syn-gas.
• Low temperatures (800 950 C)induce low NOx
  emissions.

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Conclusion

• Advantages of TW compared to raw wood
• Lower moisture content and higher specific
  calorific values compared to biomass.
• Hydrophobic nature the material does not regain
  humidity in storage and therefore unlike wood and
  charcoal, it is stable and with well defined
  composition.
• Friable nature easy to pulverise. This
  facilitates the use in a fluid-bed gasifier.

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Outlook

• Further technical investigation into the
  torrefaction process, use of syn-gas and
  transport has to be done.
• Two new subjects have to be explored
• Environment / Sustainability
• Economics
• The integral view has to be composed.