Thermogravimetric and Kinetic Analysis of Waste Biomass and Plastic Mixtures

Thermogravimetric and kinetic analysis of biomass and plastic co-pyrolysis can provide valuable inputs for a better understanding of decomposition mechanisms. Such inputs are important for selecting the appropriate process conditions but can also be helpful for process modelling. This work investigates the properties of heterogenous sawdust in a mixture with polypropylene and polystyrene. Thermogravimetric analysis is conducted to determine the decomposition mechanism and kinetic parameters of investigated mixtures and to derive appropriate conclusions regarding their further utilization potential. Co-pyrolysis was performed on mixtures with the following biomass/plastic ratios: 75-25%, 50-50%, 25-75%, over a temperature range of 30-550 °C, at four heating rates 5, 10, 20, and 30 °C/min, with pure argon as a carrier gas. Obtained results were then subjected to comprehensive kinetic and thermodynamic analysis. The primary goal was to determine effective activation energies using model-free methods, pre-exponential factors, and elementary thermodynamic parameters such as changes in enthalpy, entropy, and free Gibbs energy. Finally, the influence of the heating rate and mixture composition was extensively investigated by analyzing calculated parameters. &nbs

Impact of fuel quality and burner capacity on the performance of wood pellet stove

Pellet stoves may play an important role in Serbia in the future when fossil fuel fired conventional heating appliances are replaced by more efficient and environmentally friendly devices. Experimental investigation was conducted in order to examine the influence of wood pellet quality, as well as burner capacity (6, 8, and 10 kW), used in the same stove configuration, on the performance of pellet stove with declared nameplate capacity of 8 kW. The results obtained showed that in case of nominal load and combustion of pellets recommended by the stove manufacturer, stove efficiency of 80.03% was achieved The use of lower quality pellet caused additional 1.13 kW reduction in heat output in case of nominal load and 0.63 kW in case of reduced load This was attributed to less favourable properties and lower bulk and particle density of lower quality pellet. The use of different burner capacity has shown to have little effect on heat output and efficiency of the stove when pre-set values in the control system of the stove were not altered It is concluded that replacement of the burner only is not sufficient to increase/decrease the declared capacity of the same stove configuration, meaning that additional measures are necessaly. These measures include a new set-up of the stove control system, which needy to be properly adjusted for each alteration in stove configuration. Without the adjustment mentioned, declared capacity of the stove cannot be altered, while its CO emission shall be considerably increase

Application of different turbulence models for improving construction of small-scale boiler fired by solid fuel

Due to the rapid progress in computer hardware and software, CFD became a powerful and effective tool for implementation turbulence modeling in defined combustion mathematical models in the complex boiler geometries. In this paper the commercial CFD package, ANSYS FLUENT was used to model fluid flow through the boiler, in order to define velocity field and predict pressure drop. Mathematical modeling was carried out with application of Standard, RNG, and Realizable k-epsilon turbulence model using the constants presented in literature. Three boilers geometry were examined with application of three different turbulence models with variants, which means consideration of 7 turbulence model arrangements in FLUENT. The obtained model results are presented and compared with data collected from experimental tests. All experimental tests were performed according to procedures defined in the standard SRPS EN 303-5 and obtained results are presented in this paper for all three examined geometries. This approach was used for improving construction of boiler fired by solid fuel with heat output up to 35 kW and for selection of the most convenient construction

Investigations of combustion process in combined cooker-boiler fired on solid fuels

The aim of the investigation was to make some reconstructions on the existing stove used for cooking and baking and to obtain the combined cooker-boiler which will fulfill the demands of European standard EN 12815. Implementation of modern scientific achievements in the field of combustion on stoves and furnaces fired on solid fuels was used. During the investigations four various constructions were made with different fresh air inlet and secondary air supply with the intention to obtain more complete combustion with increased efficiency and reduced CO emission. Three different fuels were used: firewood, coal, and wood briquette. A numerous parameters were measured: fuel weight changes during the combustion process, temperature of inlet and outlet water, flue gas composition (O2, CO, SO2, CO2, NOx), flue gas temperature, ash quantity etc. The result of the investigations is the stove with the efficiency of more than 75% - boiler Class 1 (according EN 12815) and CO emission of about 1% v/v. The results obtained during the measurements were used as parameters for modeling of combustion process

The impact of production operating parameters on mechanical and thermophysical characteristics of commercial wood pellets

This study presents the experimental results of the mechanical and thermophysical properties of wood pellet samples important for their utilization in pellet stoves and boilers for heat production. The impact of operational parameters during the production process on a single pelletizer unit for three typical domestic commercial wood pellet samples (PWP110, BWP110, and BWP140) on fuel particle mechanical characteristics and related thermal properties was analyzed. It was concluded that the changes in raw material selection, as well as related operating parameters (extrusion length, i.e., die temperature during production process), have influenced the key mechanical and thermal characteristics of tested commercial wood pellets. The presented results have indicated the existence of a thin solid layer (due to waxes and subsequently lignin coating layer behaviors depending on their glass transition temperatures) on the surface of the BWP140 pellet sample. This layer leads to increasing the thermal resistance in the considered sample which can be explained by decreasing the effective thermal conductivity. Also, the forming of this layer on the surface of the wood pellet sample was caused by the production process (high-temperature impact explained by increasing friction between the die and feedstock during pellets production). It could be related to a lower value of effective thermal conductivity and specific heat capacity for considered (Beech) wood pellet sample

Thermogravimetric kinetic study of solid recovered fuels pyrolysis

In the Republic of Serbia there are significant quantities of coffee and tire wastes that can be utilized as Solid Recovered Fuel (SRF) and used as an additional fuel for co-combustion with coal and biomass in energy production and cement industry sectors. Differences between SRF and base fuel are a cause of numerous problems in design of burners. The objective of this study was to determine the kinetic parameters for the thermochemical conversion of selected SRF using Simultaneous Thermal Analysis (STA). Samples of coffee and tire waste were used for the experimental tests. Thermal analysis was carried out in nitrogen atmosphere at three different heating rates 10, 15 and 20 K/min for each sample, while it was heated from room temperature up to 900 degrees C. Two sample sizes x lt 0.25 mm and 0.25 lt x lt 0.5 mm of each SRF were used in experiments, in order to obtain reliable Thermal Gravimetric Analysis (TGA) data for estimation of kinetic parameters for SRF pyrolysis. Experimental results were used for determination of pre-exponential factor and activation energy according to methods presented in the literature. Presented research provides valuable data of coffee and tire waste that can be used for the burners design

Research Overview, Gaps, and Recommendations

<p>Modeling biomass supply and logistics has been included both directly and indirectly in European research and several initiatives have taken place through the last 15 years. Research has evolved from narrow assessments covering single or a few feedstock types and specific regions to harmonized approaches with consistent algorithms applied across Europe at different regional and temporal scales.The aim of this chapter is to provide an overview of research work in the area, identify gaps in research knowledge, and provide recommendations for future to research in the field of modeling biomass supply and logistics.</p

Research Overview, Gaps, and Recommendations

<p>Modeling biomass supply and logistics has been included both directly and indirectly in European research and several initiatives have taken place through the last 15 years. Research has evolved from narrow assessments covering single or a few feedstock types and specific regions to harmonized approaches with consistent algorithms applied across Europe at different regional and temporal scales.The aim of this chapter is to provide an overview of research work in the area, identify gaps in research knowledge, and provide recommendations for future to research in the field of modeling biomass supply and logistics.</p

Research Overview, Gaps, and Recommendations

Modeling biomass supply and logistics has been included both directly and indirectly in European research and several initiatives have taken place through the last 15 years. Research has evolved from narrow assessments covering single or a few feedstock types and specific regions to harmonized approaches with consistent algorithms applied across Europe at different regional and temporal scales.The aim of this chapter is to provide an overview of research work in the area, identify gaps in research knowledge, and provide recommendations for future to research in the field of modeling biomass supply and logistics.</p