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Challenging fuel mixtures

Characterisation of challenging fuel mixture combustion behaviour beforehand saves money!


​To reduce CO2 emissions in energy production one option is to use CO2 neutral energy sources such as biomass:
There are, however, very different types of biomass fuels available from industrial by-products like bark or saw dust to fast-growing energy crops. The nature of these fuel types differs a lot from each other, mostly due to ash behaviour characteristics. VTT has acquired an understanding of ash behaviour characteristics and developed methods to prevent ash deposition and high temperature corrosion.

VTT has gained an understanding of and developed methods to prevent ash deposition and high temperature corrosion during biomass and waste-derived fuel combustion. The patented method (CorroStopTM) has been sold out. Based on previous knowledge, we have developed a new concept around combustion additives or the co-combustion process to considerably increase power generation efficiency in biomass and waste-to-energy concepts based on CFB combustion technology (CINDY®).

Comprehensive R&D tools for understanding ash related phenomena in combustion

Our core competence is based on experimental work that can be carried out applying our pilot-scale BFB and CFB test units. We have also developed in-furnace sampling methods for ash-related aerosols that vapourize during the combustion process in furnace and later form PM1 (<1 μm) particles KCl, NaCl, ZnCl2, PbCl2, KBr, NaBr causing most of the operational problems such as fouling and corrosion of the heat transfer surfaces. Based on experimental work and high quality sampling methods, we are able to create an understanding of the nature of ash behaviour and ash-related problems. This is not only at pilot-scale, but the measurements can be performed also at power plants to screen out fuel combustion behaviour. The result can be utilised to optimise fuel mixture at the power plant in order to ensure operational performance and high availability.

VTT’s unique research facilities and methods to optimise fuel mixture according to customers needs

To develop a comprehensive understanding of ash chemistry in combustion processes we employ our BFB and CFB pilot plants as well as a fine particle measuring system that has been developed by VTT. The unique sampling system consists of probe, gas dilution phases, heated lines, solid separators, two parallel Dekati low pressure mass impactors (DLPI) and electrical low pressure impactor (ELPI). There are also FTIR-based gas analysers and O2 analyser connected to the same sampling line. This concept has been utilized by power companies to quarantee safe share of risky fuel in co-firing, optimise the use of additives for corrosion mitigation, to clear out mechanisms of waterwall and superheater corrosion, etc.