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USING ASH IN A SUSTAINABLE SOCIETY, SWEDISH R&D PROGRAM 2002-2011. Innsbruck 22-23 mars 2010. Claes Ribbing SVENSKA ENERGIASKOR AB. www.energiaskor.se www.varmeforsk.se. The Vision of the Ash Program.
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USING ASH IN A SUSTAINABLE SOCIETY, SWEDISH R&D PROGRAM 2002-2011 Innsbruck 22-23 mars 2010 Claes Ribbing SVENSKA ENERGIASKOR AB www.energiaskor.se www.varmeforsk.se
The Vision of the Ash Program Combustion residues are resources in a sustainable society
Research program Environmentally friendly uses of none coal ashes 1 m€/year since 2002. 40 companies and authorities The Thermal Enginiering Research Institute of Sweden Land filling. Forestry Environment Geotechnigue • Recycling • When outtake of energy • Extra Growth • Criteria's • Expound laws • Test methods • Quality control • Roads • Surfaces • Concrete • Mining • Dense layers • Stabilization • Covering Mine Tailings
Results • The results are the results from the scientists. • The Authorities don't automatically agree • Specially not about the balance between • The AIM of None toxic Nature • Using wastes as resources
Ash content in different fuelsThe Ash Program works with all their ashes • 25% in municipal wastes • Municipal waste contains up to 85% of bioenergi - but is not a subject for this presentation • 5% in peat (can be much more) • 10-50% in sludge from paper industry • 2-4% in bark, needles and branches • 0,2-0,5% in pure wood Claes Ribbing, Svenska EnergiAskor AB
Boilers(the Pictures show rebuilt boilers at Söderenergi) Powder cumbustion Peat, pellets (coal) ≈ 1 200 °C Fly ashes dominate Grate boiler Incinerators and Smaller boilers less than 100 MW All fuels as bark, wood chips industrial+ household Wastes etc 1 100 °C Bottom ashes dominate Fluidised bed. All fuels as wood chips, peat, wastes ≈ 850 °C Often equal amount fly/bottom ashes low NOx
Use of ashes in Sweden 2006Problem: Many small producers • Roads etc 200 kton • Forestry, Arable land 35 kton • Backfillning to cavities 50 kton (APC) • Construction on landfills 650 kton • Others, unknown175kton • Total 1 milj ton • Production 1,3 milj ton T • Construction on landfillswillmore or less disappearwithin 10-15 years
Ashes to forests A Cd ion from a rottening branch is not better than the same ion from returned ash Outtake of bio energy (branches and tops) demands recycling of ashes =(basic) minerals to get a sustainable forestry. • The ash must be matured before spreading • not to “burn” the ground • It is rather costly
Ashes and growth of forests • In most of Sweden Nitrogen limits the rate of growth of trees • at rich forest soils, ashes increases the release of in soil bound N which increases the growth • Ditched peat soils need the minerals of ashes to get a good growth. • When the deposition of N is high, Phosphorus is the limit for growth
P budget for different harvesting scenarios for forests in Sweden Whole-treeharvesting No harvesting Stem harvesting (Akselsson et al., 2008)
Conclusion • When you take out both the stem and bio energy in form of tops and branches you have to return the ashes to get a sustainable forestry • Otherwise in the long run P and other elements will be deficient. (not only in Sweden?)
Nordic innovation centrereport TR 613 2008A report most of you should intereted in • GUIDELINE FOR CLASSIFICATION OF ASH • FROM SOLID BIOFUELS AND PEAT UTILISED • FOR RECYCLING AND FERTILIZING • IN FORESTRY AND AGRICULTURE • info@nordicinnovation.net • www.nordicinnovation.net
Dense layers 50/50 of fly ashes and digested sewage sludges (dry wt)when closure of landfills • It is dense: <10-9m/s • It has an OK shear strength >30kPa • It stands settlements • It is long lasting: the biological and chemical degrading are very, very slow (High pH, Salts, Low perculation) Dense layer trails at Dragmossen Claes Ribbing, Svenska EnergiAskor AB
The Tveta method • After a lot of research work • At the Tveta Landfill they use wastes and specially ashes in all layers Layer composition for the landfill cover system
Bio/waste ashes in concrete • In concrete, bio fly ashes are good fillers and can replace a lot of Portland cement • Clorides (0,1% Cl in the paste) are a problem, they corrode the armouring-iron. • Low quality concretes are preferred markets.
Bio fly ashes in roadsin the sublevels • Stiffer and stronger roads • Stabilizes bad/old materials • Less material! 1/4! • Much better frost heave resistant • Less maintenance • No measured impact on environment • Light weight construction
Constructions with fly ashes This plant for recycling of domestic wastes – is a light weight construction of wood/peat fly ash on clay soil • Ports must be dreged • Stabilizing dredged material is an interesting market possibility for different fly ashes. (photo OY Ramboll). .
Constructions with bottom ashes • Grate boiler bottom ashes are good road building materials • Even if the test results on water upptake are high • Better the more sintered the ash is. • Powder bottom ashes are often poorer due too high amount of unburnt. • Fluid bed bottom ashes are too fine or too narrow sized to be good.
Test methods Normal test methods don't suite and don't give justice to weak materials Bottom ashes shall be tested with functional test methods as the dynamic triaxial method .
Modelling of Low Riskto health and environment • 1/100 000 risk to get damaged • To get cancer (not to die of it) • For one individual in the most exposed group • That leads to very improbable and conservative scenarios. • Shall not increase the the amount of undesired impurities above normal variations in the recipient • Shall not contaminate the groundwater as to the TAC-model for landfills
The critical scenario for low risk using Ashes as 0,5m thick sublevel in roads without other restrictions Dust on vegetables are more critical than leaching! Scenario: 1/3 of his yearly intake of Vegetables. He hardly washes them. Dust from Building the road + maintenance and demolition 20m For gravel roads are calculated that ash is not used in the surface layer but some ash reaches the surface through maintenance. Moderate trafficcreates dust during 64 years and 5% of the dust is ash. Modelling gives: Is a low risk for using bioashes i sublevels!
Uses shall be given priority when the risk for health and environment is low • Modelling and tests give that most ashes can be used as resources in a sustainable society
Thanks for your attentionclaes.ribbing@energiaskor.seyou are welcomed to mail meThis presentation will be published atwww.energiaskor.se The synthesises of the Ash Programme 2002-2008 (report 1111) and the database ALLASKA are published in English at www.varmeforsk.se Don´t forget TR 613 www.nordicinnovation.net