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Combustion is the most commonly used technology to produce energy from biomass; nevertheless, there are still thermal efficiency problems in current biomass combustion furnaces and a lack of knowledge about the properties of residual biomasses that could be used as fuels. Aiming to contribute to knowledge of the potential of residual biomass for energy generation, this work reports on the implementation of a 2D computational model to study the combustion performance of several solid biomass fuels, and its application in the analysis of Lippia origanoides bagasse combustion. The model uses an Eulerian–Lagrangian approach; in the continuous phase, governing equations are solved, and in the dispersed phase, particles are tracked and the mass, momentum, species and energy transfer between the phases are calculated. The model was validated against experimental data from a combustor fueled by three biomasses: wood pellets, olive stone and almond shell. The results show deviations of less than 13%, with few exceptions, which indicates a good degree of agreement with experimental measurements compared with those reported by other studies on the subject. Furthermore, it was found that the stems of Lippia origanoides bagasse show similar performance to that of other biomass used as solid fuel, while the leaves present lower performance. [ABSTRACT FROM AUTHOR]

The increasing use of biomass combustion systems as household appliances for heat generation is causing concern about local air quality. Areas with high concentrations of particulate matter (PM) emissions are linked to health risks. There is a need for a removal device that collects the particles before they reach the atmosphere. Electrostatic precipitators (ESPs) are the most suitable option. In this study, a laboratory-scale prototype ESP was tested with a pellet boiler. Retention efficiencies above 90% were obtained with three different discharge electrode dispositions. The continuous operation of the ESP was achieved with a dynamic control system despite fluctuations in emissions, gas conditions, etc. The accumulation of particles on inner ESP surfaces over the operation time reduced the effectiveness of the electric field, and thus retention efficiency. In this study, the retention efficiency fell from 90% to 31% in 34 h. [ABSTRACT FROM AUTHOR]

In this study, an experimental approach was utilized to assess the viability of three biomass fuels in a small laboratory-scale combustor. Three feedstocks currently considered as residues were selected based on their widespread presence in the Euroregion Galicia-North Portugal, and some were modified to improve their behavior by removing fine particles or adding substances to increase the melting point of the ashes. The experimental facility was a highly modifiable, fixed-bed combustor with air-staging capabilities and a wide array of sensors intended to measure a large quantity of parameters. A series of tests was performed to cover the widest range of total air flows possible for the facility, with values of 0.223, 0.279 and 0.334 kg/m²s being used, while 30% of the total air flow enters from below the combustion bed and 70% over it. Results from the proximate and elemental analyses show high proportions of ash in every fuel compared to commercial wood pellets, and empirical deposition indexes suggest a high risk of fouling and slagging. Testing confirmed the analysis predictions, resulting in the kiwi- and vine-based fuels not being suitable for a facility without ash elimination systems. Some modifications of the gorse fuel showed improved behavior compared to unmodified gorse fuel, namely, the addition of a 2% mass fraction of CaCO3 and the removal of fine particles. The former prevented ash sintering, and the latter greatly decreased the fouling of the heat exchanger tubes. These results suggest that some of the vegetal species studied might be suitable for their use in small-scale biomass burners, and besides the accuracy of one of the deposition indexes used is confirmed. [ABSTRACT FROM AUTHOR]