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JOULE JOR3-CT95-0001
Fractionated heavy metal separation and ash utilisation in biomass combustion and gasification plants
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Contacts
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JOULE/THERMIE Programme
:
Separation/Fractionation
:
Solid Biofuels
:
Thermochemical Conversion
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|
Type of Project |
Shared Cost |
| Contract No |
JOR3-CT95-0001 |
| EC Contribution |
886,200 ECU |
| Start Date |
01/12/95 |
| Duration |
30 Months |
Fractionated heavy metal separation and ash utilisation in biomass combustion and gasification
plants
Objectives
In order to establish a truly sustainable thermal utilisation of biomass, it is necessary not only to
close the carbon dioxide cycle, which is possible through a sustainable wood culture, but also to close
the natural cycle by recycling the ash. Previous research has shown that total recycling of wood ash leads
to environmental pollution by heavy metal deposition in the forest ecosystem. Consequently, it is
necessary to separate a small side stream, as rich in heavy metals as possible, in order to be able to
utilise the maximum amount of wood ash produced. The more effectively this heavy metal fractionation
works in practice, the higher the concentration of heavy metals in the small separated ash fraction.
Following this approach, a stable closed-cycle economy could be realised.
Technical Approach
This project focuses on the following main points:
- standardisation of methods for taking ash and fuel samples, for sample preparation
(homogenisation) and for the complete detection of elements in ashes and biofuels in order to guarantee
comparable results between the project Participants
- test runs to investigate the potential of fractionated heavy metal separation in two straw incinerators,
one wood-fired CFB-combustion, one wood-fired downdraft gasification and one bark-fired
BFB-gasification plant
- basic research on modelling high temperature equilibrium and the condensation/aerosol formation
of easily volatile heavy metals in flue gases of combustion/gasification plants in order to explain the
experimental results and to derive functional correlations. This modelling will be supported by pilot plant
experiments for parameter adaptation
- basic laboratory research on the potential for heavy metal recovery from highly contaminated
fly-ash fractions by thermal ash treatment and bio-leaching in order to recycle raw materials and to
avoid ash disposal
- calculation of ecological and economical impacts for the process of thermal energy utilisation and
for the ecosystems concerned by stream analyses for minerals and heavy metals and by using dynamic
compartment models for the impact of ash recycling on soils, plants and the ground water.
Expected Results
- Standardised sampling, sample preparation and analysis of trace elements in biomass fuels and
ashes will be developed.
- Techniques for fractionation of heavy metals in combustion/gasification plant as well as the
possibility of treatment of highly contaminated ash fractions by thermal treatment or/and bioleaching
will be suggested.
- Two Participants (an SME and a large enterprise) will utilise the results of this project for the
construction of new plants.
- Development of ready-to-use models for high temperature equilibrium calculations for heavy
metals and for particle and aerosol formation in combustion/gasification processes and for the general
economic and ecological evaluation of biomass ash utilisation.
Contacts
Coordinator
Participant
