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The pyrolysis process of two low-rank coals (lignite Kostolac and Kolubara), and two waste materials (spent coffee ground and tyre rubber granulate) as well as their blends, have been examined by preliminary thermogravimetric analysis. Thermal decomposition experiments were performed in an N2 atmosphere on raw (pyrolysis) and blend (co-pyrolysis) samples at heating rates of 10, 15, and 20 K min-1. The lignite-waste blend was created in the following mass percentage ratios 90:10, 80:20, and 70:30. Based on obtained experimental data, the strong interactions were identified between the examined lignite and waste materials during copyrolysis, indicating the presence of a positive synergistic effect. The characteristics of the raw waste sample and the heating rate were recognized as two key parameters that influenced the synergy result with lignite sample, in lignite-spent coffee ground blends. For lignite-waste rubber granulate blends, the blending ratio is critical for beneficial synergistic effect (ratios of waste rubber granulate with lignite less than 30% are preferred). The probable synergistic mechanisms were further explained using performed kinetic analysis by varying the effective activation energy with temperature and conversion. In addition, the influence of micro-scale condition characteristics such as heating rate (as the experimental regulatory factor) on the magnitude response of synergistic effect during co-pyrolysis was also investigated in this work.

The fuel-NOx emissions during the conversion of carbon-based feedstock into energy and chemicals are on a global level in focus last decades due to environmental issues. The emission of nitrogen oxides is recognized among the other pollutants, as one of the key environmental problems related to energy production by various types of feedstocks. In this paper, the effect of fuel-based nitrogen delivery on the development of NOx precursors (HCN and NH3) during the devolatilization process of properly selected samples (coal, sawdust, wheat straw, and ground coffee waste) has been examined. TG-DTG thermal analysis techniques, coupled with mass spectrometry (MS) were used for the assessment of nitrogen distribution for HCN and NH3 gases, as intermediate species during feedstocks devolatilization, which directly influences the NOx emission during thermochemical conversion processes (pyrolysis and combustion). The mass balance of nitrogen together with performed EGA (evolved gas analysis), and the distribution of nitrogen between volatiles and formed char were also determined. The obtained data for investigated samples could be exploited for further thermochemical process optimization, in regard to NOx emissions. The presented results could be used as the experimentally determined input parameters for the mathematical modeling of indicated processes, and with further analysis can be transferred to large-scale industrial plant applications.

Low-rank coal, characterized by its high moisture, ash, and volatile matter content, besides the significant contribution to GHG emission, can be challenging to combust efficiently. Biomass, on the other hand, is a renewable energy source that can enhance combustion performance and reduce emissions. The transition from fossil fuels to renewables should involve the co-combustion of coal and biomass which requires a detailed understanding of their individual and combined combustion kinetics. In this paper, the model-based kinetic modelling approach is applied to studying the thermal decomposition of coal and biomass using a combination of experimental data and mathematical models. By quantifying the rates at which various components of these fuels degraded and release heat, the optimization of process parameters, enhanced energy efficiency, and minimized environmental impacts could be achieved. The obtained results presented in the manuscript offers several advantages in comparison with the standard fuel characterization techniques. For example, the non-additive issues for different fuel characteristics could be overcome. Furthermore, the ability to predict combustion behaviour under different operating conditions, optimize burner designs, and develop cleaner combustion technologies could be enabled. In that sense, performed research in this paper could further supports the transition towards sustainable and carbon-neutral energy systems by harnessing the energy potential of low-rank coal while utilizing biomass as a clean and renewable co-fuel.

The fuel-NOx emissions during the conversion of carbon-based feedstock into energy and chemicals are on a global level in focus last decades due to environmental issues. The emission of nitrogen oxides is recognized among the other pollutants, as one of the key environmental problems related to energy production by various types of feedstocks. In this paper, the effect of fuel-based nitrogen delivery on the development of NOx precursors (HCN and NH3) during the devolatilization process of properly selected samples (coal, sawdust, wheat straw, and ground coffee waste) has been examined. TG-DTG thermal analysis techniques, coupled with mass spectrometry (MS) were used for the assessment of nitrogen distribution for HCN and NH3 gases, as intermediate species during feedstocks devolatilization, which directly influences the NOx emission during thermochemical conversion processes (pyrolysis and combustion). The mass balance of nitrogen together with performed EGA (evolved gas analysis), and the distribution of nitrogen between volatiles and formed char were also determined. The obtained data for investigated samples could be exploited for further thermochemical process optimization, in regard to NOx emissions. The presented results could be used as the experimentally determined input parameters for the mathematical modeling of indicated processes, and with further analysis can be transferred to large-scale industrial plant applications.

This work provides insight into possibilities of maximum utilization of C3-C4 energy crops for thermo-chemical conversion (slow pyrolysis) into high value biochemicals, platform chemicals, drop-in fuels and combustible gases, using coupled kinetic and thermodynamic analyses. In order to examine the kinetics of decomposition of lignocellulosic components, model-free and model-based methods faded from thermal analysis data were used. Thermodynamic compensation was used for explicatory of entropy controlled process, where conformational changes and chemical exchange directly affect the type and distribution of obtained pyrolytic products. It was shown that external variable (i.e. the heating rate/temperature) does not change either an entire reaction mechanism (mechanistic nature of MG and AD pyrolyses) or transition state, but it changes activation enthalpy and activation entropy which lead to differences in terms of heat energy consumption, pyrolysis favorability and thus rates of generation of activated complex among feedstocks. To investigate the interplay of catalysts (present in feedstocks as minerals) and reactants, selective energy transfer (SET) model was applied. The model showed an activity of catalyst with different outputs towards two reactants, lignin part of the structure in MG and 1,8-cineole in AD. It was shown that AD is more convenient for thermal conversion than MG, regarding to lower transformation energy requirement, higher reactivity, as well as much faster accumulation of products. © 2023 Elsevier B.V.

The actual paper analyses the performance of different energy crop biomasses, Miscanthus x giganteus Greef et Deu (EC-1) and Arundo donax L. (EC-2) stems, during slow pyrolysis process monitored by simultaneous TG-DTG-MS techniques, through chemical exergy analysis. In addition to considering the physical and chemical characteristics of given feedstocks for their efficient thermo-chemical conversion into pyrolytic gas, in this study, a theoretical simulation for their implementation use in the gasification process was also performed. The performed thermodynamic study with detailed exergy analysis showed that the large contribution of exergy in syngas components such as CO and H2 originates primarily from cellulose pyrolysis of EC-1, while large exergy contribution in syngas component as CH4 originates from lignin pyrolysis of EC-2. It was founded that the exergy efficiency of syngas for EC-1 equals 19.04%, which is lower than the exergy efficiency of syngas for EC-2 (20.46%), as a result of higher ash content in EC-1. Also, it was reported that higher carbon (C) and hydrogen (H) contents present in the EC-2 sample generate higher gaseous energy and exergy values, i.e. the increment of exergy efficiency of syngas, by both approaches (pyrolysis and gasification exergy analysis), but results in a lower biomass chemical exergy (18.28 MJ kg−1). The methodology applied to the gasification process was shown a higher exergy efficiency for EC-2 (∼36 – 42%) than for EC-1 (∼33 – 39%), dependant on the equivalence ratio (ER).

The presented paper deals with the influence of the heating rate on combustion characteristics (reactivity and reactivity evaluation, ignition index (Di), burnout index (Df), the combustion performance index (S), and the combustion stability index (RW)) of the protective coronavirus face masks. Two types of commonly used face masks in different state (new and exploited) were investigated by TG-DTG analysis in an air atmosphere, directly coupled with mass spectrometry (MS). Based on the experimental results, the impact of ultimate and proximate analysis data on the evolved gas analysis (EGA) was discussed. Also, the derived values from thermo-analytical (TA) data were compared with the literature reports, related to individual constitutive face mask materials. According to the performed research, it was established that different maximal reaction rate values at various heating rates indicate the complex nature of coronavirus face mask thermo-oxidative degradation, which is stimulated with carbon oxidation reactions and volatile matter (VM) release. By detailed analysis of obtained TG-DTG profiles, it was established that process takes place through the multiple-step reaction pathways, due to many vigorous radical reactions, causes by polymers degradation. The performed research was done to evaluate the possible utilization of coronavirus waste to energy production and sustainable pandemic environmental risk reduction.

The preliminary thermogravimetric studies of co-pyrolyzed low rank coals (lignites Kostolac and Kolubara) with waste materials (spent coffee ground and waste rubber granulate) in a form of blends have been performed. Thermal analysis measurements of blend samples were carried out in a nitrogen, atmosphere at three different heating rates of 10, 15, and 20 K per minute. The coal-waste blends were prepared in the percentage ratios of 90:10, 80:20, and 70:30. This work analyzed the synergy analysis for considered blends shown via descriptive parameters during co-pyrolysis process. According to the performed analysis, the presence of synergistic effect was identified, where strong interactions were also observed. For lignite-spent coffee ground blends, it was found that two factors which affect the synergy effect with coal are concentration of added biomass material and the heating rate. For lignite-tire rubber granulate blends, the blending ratio take on a decisive role for positive consequences of a synergistic effect (ratios below 30% of tire rubber granulate in coals are desirable). Also, in this work the influence of micro-scale condition parameters such as heating rate (as the experimental regulatory factor) was analyzed on the magnitude response of synergism during co-pyrolysis.

Rapid industrialization together with issues over the depletion of traditional fuel supplies and environmental concerns have prompted researchers to look into developing an environmentally safe, renewable, costeffective, and long-term alternative energy source. Agriculture biomass is recognized as a potentially viable solution for utilization in the energy sector for achieving the sustainable and long-term transformation into energy and/or fuels. This type of biomass is generated in large amounts across the world, which may be converted to biofuels using a variety of methods. However, concerns related to the competing agricultural biomass applications need to be thoroughly examined taking into account both the short- and long-term actuality, and its impact on the soil by conversion to biofuels. According to common practice agriculturalbiomass is dominantly used for biogas production due to its availability and simplicity of handling. Based on all mentioned the assessment of the most applicable raw materials for biogas production is essential for achievingthe sustainability criteria and promoting using biomass for energy production. In this paper, a theoretical approach was applied for experimentally obtained results of proximate and ultimate analysis of different biomass materials as a possible feedstock for biomass production. Based on data of proximate and ultimate analysis the theoretical biomechanical methane potential (TBMP) for considered samples was calculated. According to obtained results, agricultural biomass shows validity of use for biogas production considering the fulfillment of the raw material minimum quantity.

A pressurized drop tube furnace was used to study the pyrolysis behavior of bituminous and lignite coal at elevated pressure. Experiments were conducted at the pressure range from 1 to 10 atm in 100% N-2 or 100% CO2 atmosphere. The volatile yields, char morphology, swelling ratio, and pore structure were discussed in detail. The results show that the pressure, atmosphere and coal rank could effect on the volatile releasing and char evolution significantly. In N-2 atmosphere, the total volatile yields of YL and NM coal decrease as the pressure elevated, while in CO2 atmosphere, the mass release of NM coal increases at high pressure contributed by the reaction of CO2 with organic macromolecule inside the particles; different with bituminous coal, no significant swelling behavior is found with the increase of pressure; the BET surface area of YL char decreases as the pressure increases, while for lignite coal, in N-2 atmosphere and at high pressure, less macro pores are formed, which could contribute to the BET surface area. While in CO2 atmosphere, the CO2-macromocular organic reaction would promote the volatile releasing, and the BET surface area decreases significantly at high pressure.

The preliminary thermogravimetric studies of co-pyrolyzed low rank coals (lignites Kostolac and Kolubara) with waste materials (spent coffee ground and waste rubber granulate) in a form of blends have been performed. Thermal analysis measurements of blend samples were carried out in a nitrogen, atmosphere at three different heating rates of 10, 15, and 20 K per minute. The coal-waste blends were prepared in the percentage ratios of 90:10, 80:20, and 70:30. This work analyzed the synergy analysis for considered blends shown via descriptive parameters during co-pyrolysis process. According to the performed analysis, the presence of synergistic effect was identified, where strong interactions were also observed. For lignite-spent coffee ground blends, it was found that two factors which affect the synergy effect with coal are concentration of added biomass material and the heating rate. For lignite-tire rubber granulate blends, the blending ratio take on a decisive role for positive consequences of a synergistic effect (ratios below 30% of tire rubber granulate in coals are desirable). Also, in this work the influence of micro-scale condition parameters such as heating rate (as the experimental regulatory factor) was analyzed on the magnitude response of synergism during co-pyrolysis.

У раду је приказан развијени софтверски систем за прорачун топлотних шема постројења са парним турбинама и припадајућим моделима за одређивање радних параметара појединачних компоненти оваквих постројења. У току развоја оваквог система анализиране су различите методе доступне у литератури. На основу развијених модела и целокупне методологије прорачуна, написан је рачунарски програм са графичким интерфејсом, широког спектра примене. Програм је конципиран и развијен на начин да поседује флексибилност у погледу конфигурисања прорачунаване топлотне шеме постројења, те се може примењивати за различите типове турбопостројења, с тим да се у оквиру топлотне шеме различите компоненте се могу неограничено додавати. За сваку од компоненти развијен је одговарајући математички модел који омогућава процену њених геометријских карактеристика (дизајн мод), као и развијени модел који омогућава симулацију њеног рада при промени радних услова (анализа мод). Радни услови постројења могу бити унапред задати или су резултат мерења у току рада реалног погона на основу аквизиције и обраде података. Програм је робустан и захтева кратко време за спровођење прорачуна. Имплементирани модели и целокупна метода прорачуна су вишеструко валидирани поређењем са резултатима термотехничких пријемних и погонских испитивања парних турбина и турбопостројења спроведених од стране Лабораторије за топлотне турбомашине и термоенергетска постројења Машинског факултета. Тиме је постигнут висок степен поузданости добијене методологије и тачности резултата, како при пројектовању нових постројења, тако и при анализи рада постојећих погона. За валидацију су коришћени резултати испитивања турбопостројења снаге од 120 до 665 MW, са поткритичним и наткритичним параметрима свеже паре. Развијени систем је више пута успешно примењен за анализу рада постројења планираних за изградњу, као и приликом разматрања модернизације постојећих блокова. Такође, систем уз неопходна проширења и интеграцију са мерним системом електра, The thesis presents a developed system for calculating heat balance diagrams of steam turbine plants and models for the simulation of the behavior of plant components. During the system's development, various models for the components that were available in the literature were analyzed. The adopted models for the calculation have been multiply validated by the conducted thermal tests of steam turbines and steam turbine plants performed in the previous period by the Laboratory for Thermal Turbomachines. In this way, a high degree of reliability of the methodology and accuracy of the results when designing new plants or analyzing existing plants' operation is achieved. During the validation, the test results of steam turbine plants with a 120 - 665 MW capacity with subcritical and supercritical parameters of fresh steam were used. Based on the developed models and systems, a computer program with a graphical interface was written, which can be used for a wide range of applications. The model for the calculation of new plants has been successfully used in the analysis of the operation of power plants that have yet to be built and the analyzes in the modernization of plants in operation. The developed program is robust, and with the short time required to perform calculations. The developed model and program for calculating heat balance diagrams of steam turbine plants are flexible, and various components can be added without restrictions. A mathematical model was developed for each component with equations that enable the calculation of the component geometry (design mode) and the simulation of operation, that is, the calculation of the component behavior under different operating conditions (analysis mode). With the necessary extensions, the developed system has been applied to monitor and analyze the operation of steam turbines, which determines the current operating characteristics of the complete plant and all its components in real-time. The system detects deviati

Предмет истраживања ове докторске дисертације је примена симултане термалне анализе и масене спектрометрије за одређивање различитих карактеристика биомасе као горива од значаја за коришћење у енергетске сврхе применом термохемијских процеса конверзије. Наведене експерименталне методе нису примарно намењене испитивању биомасе, услед чега је у оквиру ове дисертације извршено прилагођавање методологије испитивања поменутим методама за карактеризацију биомасе. С обзиром на широк спектар могућности примене експерименталне апаратуре, обрађено је више термохемијских процеса конверзије (пиролиза, гасификација и сагоревање) и обухваћен је велики број узорака биомасе (дрвна, пољопривредна и отпадна биомаса). Анализа резултата испитивања подразумевала је одређивање кинетичких параметара процеса конверзије различитих типова биомасе, а добијени резултати верификовани су објављивањем у водећим међународним и домаћим научним часописима. У наставку истраживања поред кинетичке анализе, спроведена је гасна анализа процеса применом масене спектрометрије. Гасном анализом испитивани су најзаступљенији гасови који се ослобађају током термохемијских процеса конверзије биомасе. Том приликом, развијена је методологија најпре за квалитативну анализу гасова, а потом и делимичну квантитативну анализу, што представља најзначајнији научни допринос ове докторске дисертације. Добијени резултати су потврђени поређењем са литературним изворима и публиковањем у међународним научним часописима. Ови резултати се могу искористити за оптимизацију термохемијских процеса конверзије при коришћењу биомасе, као и за процену најефикасније технологије за максимално искоришћење потенцијала биомасе, што указује на значај овог истраживачког рада, а тиме и научни допринос предметне докторске дисертације., The subject of the investigation in this thesis is the application of simultaneous thermal analysis and mass spectrometry for determination of different characteristics of biomass as a fuel which are important for energy production by thermochemical conversion processes. Considered experimental methods are not primarily proposed for biomass testing, as a result of which, within the framework of this dissertation, considered testing methodology was adopted to methods for biomass characterization. According to a wide range of possibilities for the application of experimental equipment, several thermochemical conversion processes (pyrolysis, gasification, and combustion) were processed and a large number of biomass samples (wood, agricultural, and waste biomass) were included. The analysis of test results included the determination of kinetic parameters of the respective conversion process for different types of biomass, where the obtained results were verified by publishing in international and domestic scientific journals. Further in the performed research, in addition to the kinetic analysis, the analysis of evolved gasses from conversion processes was performed using mass spectrometry. The most common gases that are released during thermochemical processes of biomass conversion were examined by gas analysis. For that purpose, a methodology was developed, first for the qualitative analysis of gases, and then for the semi-quantitative analysis, which represents the most significant scientific contribution of the dissertation. Obtained results were confirmed by comparison with literature sources and publication in international scientific journals. These results can be used to optimize thermochemical conversion processes when using biomass, as well as to evaluate the most efficient technology for maximum use of biomass potential, which indicates the importance of this research work, and thus the scientific contribution of the dissertation.

Despite many advantages of the utilization of biomass as a renewable energy source, certain bottlenecks during biomass plant operation can be identified. Transport and collection of biomass as well as non-uniform material characteristics are issues related to decreasing efficiency of logistics and fuel manipulation which can also cause economic problems with biomass collection, transport, and storage. Since biomass is an especially reactive fuel, this has raised concerns over its safe handling and utilization. Fires, and sometimes explosions, are a risk during all stages of fuel production as well as during handling and utilization of the product. This paper presents a novel method for assessing ignition risk and provides a ranking of relative risk of ignition of biomass fuels. Tests within this method include physical and chemical properties of biomass, thermal analysis measurements, and the calculation procedure steps which were made using characteristic temperatures from thermogravimetry recordings. The results of thermogravimetry analysis were used for determination of tangent slope of the mass loss rate curves in devolatilization zone at considered heating rates for all tested samples. Linear interpolation of the data obtained by tangent slope analysis and used heating rates may provide unique straight line for each sample in the ignition testing. Thermogravimetry index of spontaneous ignition (TGspi) is obtained for all samples based on newly established formula. By varying gradient of linear dependence of self-heating coefficient against reference temperatures, mass and heat transfer limitations for various biomasses were discussed. The proposed method is accurate as well as relatively simple and quick, enabling determination of data necessary for design and application of appropriate measures to reduce fire and explosion hazard related to operation of biomass.

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.

Food wastes are generated massively across global food supply chains. Conventional treatments of food waste (e.g., landfilling and incineration) could cause environmental, economic and social problems. Valorization of food waste into value-added chemicals is a more sustainable and cost-effective option. This paper investigates the slow pyrolysis as an environmentally friendly and efficient way to thermo-chemically conversion of food waste into value-added products. TGA-DTG study of slow pyrolysis of dried Goji berry pulp (GBP) samples was carried out at different heating rates. To establish pyrolysis mechanism, two kinetic approaches were used for determination of kinetic parameters: first, which involves using model-free methods and second, the use of iso-kinetic relationship analysis to identify the low and high-temperature kinetic regimes during the chemical transformation of the investigated material. It was shown that iso-kinetic temperature (363.79 °C) represents a transition from the low-kinetic regime (enzymatic hydrolysis) to the high-kinetic regime (acid hydrolysis), which strongly depends on temperature i.e. applied heating rate. Significant compensation between kinetic parameters is a consequence of a change in the mechanism of glucosides’ bond cleavage.

The emission control from coal-fired power plants is on a global level in focus last decades due to environmental issues. The emission of nitrogen oxides is recognized among the other pollutants, as the key environmental problem related to energy production by the coal utilization. In this paper, the effect of fuel nitrogen delivery on the NOx precursors (HCN and NH3) during devolatilization processes of selected coal samples (with high content of nitrogen) has been examined. TG-DTG coupled with mass spectrometry (MS) experimental techniques was used for the assessment of nitrogen distribution for HCN and NH3 as intermediate species during coal devolatilization, which directly influences the emission of nitrogen oxides during the combustion process. Further by the establishment, the mass balance of nitrogen together with performed analysis of evolved gases, the distribution of nitrogen between volatiles and char could be also determined. The obtained data for particular coal samples could be exploited for further coal combustion process optimization in regard to NOx emissions, and can be used as the experimentally determined input parameters for mathematical modeling of the coal combustion process, in the large-scale coal-fired power plants.

The presented paper deals with the influence of heating rate on combustion characteristics (reactivity and reactivity evaluation, ignition index (Di), burn-out index (Df), combustion performance index (S), and combustion stability index (RW)) of protective coronavirus face masks. Two types of commonly used face masks in different state (new and exploited) were investigated by TG-DTG analysis in air atmosphere, directly coupled with mass spectrometry (MS). Based on experimental results, the impact of ultimate and proximate analysis data on the evolved gas analysis (EGA) was disscused in detail. Also, the derived values from thermoanalytical data were compared with literature, related to individual constitutive face mask materials. According to the performed research, it was established that different maximal reaction rate values at various heating rates indicate the complex nature of coronavirus face mask thermo-oxidative degradation, which is stimulated with carbon oxidation reactions and volatile matter (VM) release. By detailed analysis of obtained TGDTG profiles, it was established that process takes place through multiple-step pathways, due to many vigorous radical reactions, causes by polymers degradation. The performed research was done to evaluate the possible utilization of coronavirus waste to energy production and sustainable pandemic environmental risk reduction.

Alternative fuels are crucial for the decarbonisation of high-energy demanding processes. The utilisation of waste materials to produce alternative fuels is especially interesting since, the co-pyrolysis of waste plastics and biomass was lately introduced as promising method since the synergistic effect might enhance the product properties compared to those from individual pyrolysis. Furthermore, the utilisation of waste biomass, like sawdust, is interesting since it does not influence the sustainability of biomass consumption, and even more, it avoids the usage of raw feedstock. Thermogravimetric analysis is per -formed to determine the thermal degradation behaviour and kinetic parameters of investigated mixtures to find the most appropriate utilisation method. Co-pyrolysis was conducted for three mixtures with the following biomass/polyurethane ratios: 75-25%, 50-50%, 25-75%, over a temperature range of 30-800 degrees C, at three heating rates 5,10 and 20 degrees C/min, under an inert atmosphere. Obtained results were subjected to comprehensive kinetic analysis to determine effective activation energy using the iso-conversional model-free methods and provide a detailed analysis of the samples' thermal degradation process. This work aimed to identify the main thermal decomposition stages during co-pyrolysis of biomass and polyurethane mixtures and provide the mixture composition's influence on the considered thermochemical conversion process.