Production of liquid biofuels derived from vegetable oils in recent years significantly increased which causes surplus of by-product (waste glycerol) from this process. Therefore it is of great importance to find cheap and fast method of use its utilization. In this study, a possibility of the utilization of technical purity glycerin as an addition to wood pellets intended for heating purposes has been investigated. Usefulness of pellets contained glycerol additions has been compared in terms of applicable quality standards for wood pellets. Effects of waste glycerol addition on concentration of combustion products as well as temperature in heat exchanger have also been examined. The experimental results show that co-combustion of waste glycerol with wood sawdust does not worsen heating efficiency in a standard boiler. Moreover, 4.5 and 7% presence of glycerol in wood pellets correlated to a nearly twofold decrease of NO_x concentration in flue gas. Therefore, the use of the waste glycerol as a binder for the production of pellets can be a simple and cost-effective solution of its utilization.

This paper presents an analysis of the pine and sunflower husks pellets combustion without and with 5% addition of waste glycerol. Usefulness of pellets contained glycerol additions has been compared in terms of applicable quality standards for biomass pellets. 10 kW domestic biomass boiler has been employed for burning tested pellets. The consumption of analyzed fuels during boiler operation was determined. Effects of waste glycerol addition on CO₂, CO, and NO_x concentrations in exhaust gases have been also examined. The experimental results show that regardless of the type of raw material, a 5% addition of waste glycerol to pellets has nearly twofold decrease NO_x concentration in flue gas and does not significantly affect changes of CO₂ and CO concentrations. Therefore, the use of the waste glycerol as a binder for the production of pellets can be a simple and cost-effective solution of its utilization.

The paper analyzes the suitability of four types of biomass pellets as a fuel for heating purposes. Three types of waste biomass (sunflower husks, rapeseed cake, and corn straw) and one type of biomass grown for energy purposes (willow) were selected. After appropriate preparation, the selected starting materials were subjected to the pelletization process. Selected physical and chemical properties of the studied biomass pellets were determined. All four types of the analyzed pellets met the EN-ISO-17225-2:2014 standard in terms of bulk density, dimensions, as well as nitrogen and moisture content. The highest calorific value was pellets made of sunflower husk (17.27 MJ/m³) and willow (16.81 MJ/m³), while the calorific value of pellets made of corn straw and rapeseed cake did not exceed 16.5 MJ/m³ and did not meet the standard. In addition, the ash content for these two types of pellets was well above the standard. A 10 kW domestic biomass boiler was employed for burning the tested pellets. The consumption of analyzed fuels during boiler operation was determined. The concentration of CO, CO₂, and NO_x in exhaust gases was also examined. The obtained experimental results were compared with the numerical calculations with the use of ANSYS Chemkin-Pro using two mechanisms. The highest concentrations of CO₂ and CO were observed during the combustion of sunflower and willow husk pellets, which probably resulted from the highest carbon content and, thus, the highest calorific value when compared to cake and straw pellets. For all analyzed pellets, the value of NO and NO₂ concentration was similar and did not exceed 368 ppm and 18 ppm, respectively. The results closest to the experiment were obtained for calculations using the mechanism developed by Glarborg et al. The research carried out in the article shows that out of the four analyzed types of pellets, only sunflower and willow husk pellets can be burned in a domestic boiler adapted to burning wood pellets, which is a cheap alternative to wood pellets.

The shortage of fossil fuels and their rising prices, as well as the global demand for renewable energy and the reduction in greenhouse gas (GHG) emissions, result in an increased interest in the production of alternative biofuels, such as biodiesel or biomass pellets. In this study, the possibility of utilizing waste glycerol, as an addition to pine pellets intended for heating purposes, has been investigated. The usefulness of pellets containing glycerol additions has been compared in terms of applicable quality standards for wood pellets. The highest values of moisture (4.58%), ash (0.5%) and bulk density (650 kg/m³) were observed for pellets without glycerin waste. The addition of waste glycerol slightly increases the calorific value of the pellet (17.94 MJ/kg for 7.5% additive). A 10-kW domestic biomass boiler has been employed to burn the tested pellets. The consumption of analyzed fuels during boiler operation was determined. The concentration of CO, CO₂ and NO_x in exhaust gases has also been examined. It was observed that the addition of 7.5% of waste glycerol contributes to the reduction in NO_x concentrations by 30 ppm and CO₂ by 0.15%. The obtained experimental results were compared with the numerical calculations made with the use of ANSYS Chemkin-Pro. The conducted research indicates the legitimacy of utilizing waste glycerol as an additive to wood pellets. In addition, this type of addition has a positive effect on, among others, the increase in calorific value, as well as lower emissions of combustion products such as NO_x and CO₂.

E3S Web of Conferences, open access proceedings in environment, energy and earth sciences

The global increase in biodiesel production releases surplus of waste glycerol. Therefore, it is of great importance to find a cheap and fast method for its utilization. The present study considers possibilities and opportunities of the use of waste glycerol as an addition to light fuel oil for heating purposes. The waste glycerol has been co-combusted with light oil at few different mass ratios in a heating chamber equipped with an integrated oil burner. The glycerol additions revealed a relatively small influence on heating efficiency and heat exchange. For mixtures containing glycerol, a noticeable decrease in the content of hazardous components (SO₂, NO_x, and CO) in exhaust gas was observed.