The main aim of this study is to provide the experimental research of the combustion characteristics for the different types of the biomass pellets during their thermo chemical conversion with estimation the correlations between the main characteristics of pelletized plant biomass and combustion characteristics. The experiments include first, the preparation of the pelletized biomass samples of different origin with certain elemental composition, heating values, moisture content, bulk and energetic density, and second, kinetic study of the combustion characteristics with local measurements of the temperature and composition of the flame reaction zone and heat production rates at different stages of the thermo chemical conversion of pelletized biomass and different air supply rates into the combustor to obtain optimal combustion conditions of plant biomass. Correlations between the main characteristics of pelletized samples and combustion/emission characteristics of pelletized biomass fuel have been derived and analyzed.
To effectively produce clean heat energy from biomass, microwave (mw) pre-processing of its different types - pelletized wood (spruce), herbaceous biomass (reed canary grass) and their mixture (50:50) - was carried out at the 2.45 GHz frequency with different durations of biomass exposure to high-frequency oscillations. To estimate the mw pre-processing effect on the structure, composition and fuel characteristics of biomass, its thermogravimetric (TG), infrared spectroscopy (FTIR) measurements and elemental analysis were made. The pre-processing is shown to enhance the release of moisture and low-calorific volatiles and the partial destruction of biomass constituents (hemicelluloses, cellulose), promoting variations in the elemental composition and heating values of biomass. The field-enhanced variations of biomass characteristics and their influence on its gasification and combustion were studied using an integrated system of a biomass gasifier and a combustor with swirl-enhanced stabilization of the flame reaction zone. The results show that the mw pre-processing of biomass pellets provides a faster weight loss at the gasification, and, therefore, faster ignition and combustion of the activated pellets along with increased output of heat energy at their burnout
The rehabilitation project of the district heating system of Rīga city envisaged elimination of district heat substations, reconstruction of individual heat substations and district heating networks. Inefficient medium and small scale heat sources were closed and the relevant consumers were connected to the networks of large scale heat sources. The major heat sources of JSC "Rīgas Siltums" were reconstructed during the project in order to provide more efficient and environmentally friendly heat production. In the course of implementing the rehabilitation project the arrangement of the heat metering, improvement of the service quality and provision of the heat consumption control to heat consumers were provided.
The paper addresses the moisture handling function in ice rinks. Dehumidification has an important role in ice rinks to avoid structural damages and maintain a sustainable indoor environment. Field measurement analysis in a number of ice rinks in Sweden is performed, showing the indoor climate dependency on the ambient conditions. Indoor temperatures vary between +5°C to +10°C and humidity ratio between 2.5 to 6.0 gH2O/kg of air. [1] Moisture source evaluation shows that the most critical load is imposed by air leakages, while internal loads such as people can generate peaks but have a short-term nature. Control strategy of the dehumidification equipment has a significant impact on the appropriate humidity level and moreover poor controls can easily lead to a 30% energy penalty. [2] [3] In ice rinks it is concluded that the acceptable setpoint is in the range of 0°C to 2°C dewpoint temperature.
Abstract:The district heating company "Rigas siltums" operates biomass fuelled boiler in Riga city. Three systems consisting of biomass boilers having a comparatively similar heat capacity and particle abatement units like multicyclons, electrostatic precipitators and flue gas condensers are compared. The main goal of the study is to evaluate the boiler plant as a system where solid particles are both emitted and caught. The results show that, the particulate matter can be efficiently trapped from flue gases by the particle abatement technologies, and the electrostatic precipitator with sufficiently large collection surfaces is able to provide appropriate flue gas treatment of the particulate matter in the biomass boilers also without pre-cleaning of the flue gas in multicyclons.
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