MultifuelLowEmission - Development of a novel multifuel biomass boiler with lowest pollutant emissions / MultifuelLowEmission

There is a need to reduce the production through combustion of air pollutants such as nitrogen oxides (NOx), fine particle matter (PM), volatile organic compounds (VOC) and carbon monoxide (CO), which damage our health and the environment. This implies a reduction in the emissions from current biomass boilers, especially NOx and PM, which have the highest environmental impact in this case. Besides, it is of special relevance to increase the fuel flexibility and, therefore, a growth in the market potential, employing in modern biomass combustion devices fuels with a higher nitrogen and ash content, such as agricultural residues, herbaceous fuels and short rotation coppice, which can lead to higher emissions that conventional wood chips. The objective of this project is the development of an innovative combustion technology with a power range up to 400 kW and based on extreme air staging, which can be applied for a broad range of solid biofuels (short rotation coppice, miscanthus or olive stones, besides wood chips). It should achieve a significant reduction in the emission of air pollutants in comparison to the current state of the art. The extreme staging combustion process (with fixedbed gasification and double staging) is a promising and innovative process that is however not yet mature. This process is not available in the market for a wide range of fuels and there are still several relevant aspects that should be researched. The formation of NOx and PM in extreme air staging is not understood in detail and, therefore, their basic principles will be experimentally investigated in this project. A lab-reactor with fixed-bed gasification and extreme air staging will be designed for this purpose, in order to scientifically investigate the factors that influence the formation of air pollutants. These experiments will be complemented with tests with a single particle reactor for analysing in detail the release of pollutant-precursors. Novel models, which are based on these experimental results, will be developed, including a CFD model for combustion and NOx formation under extreme air staging and a release model for inorganics which produce PM. Subsequently, a basic concept of this new technology will be developed and a 200 kW test facility will be constructed in order to conduct systematic experiments, supporting the simulations with the new models, with the relevant fuels and different parameters (e.g. bed fuel, fuel load, air staging, retention time and flue gas recirculation). The obtained findings will be employed in order to design a second version of the test facility and the concept will be finally optimized, based on modelling and experiments, for the operation with the previously listed fuels achieving a TRL 4. A successful conduction of this project will provide the project consortium a technological leadership in small-scale multi-fuel combustion and the company partner Hargassner will achieve a relevant competitive edge on the market.