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The presented research results the gasification process of biomass waste (brewery spend grain, wheat straw, hay, pine sawdust). Experimental investigations focused on determining the influence of gasification agent (CO2, steam, and steam and CO2 mixture) and the presence of a solid catalyst (MgO∙CaO, TiO2, CuO and SrO). Investigations were performed towards syngas production. A wide range of analyses and instrumental methods were used to determine the properties of gasification process products, including: GC, TGA, FTIR, SEM, BET. The main component of syngas obtained produced in atmosphere CO2 and steam mixture was hydrogen. The H2 concentration increased from 20% up to 44% in case of brewery spend grain. The presence of the catalyst in the gasification process favoured the tar cracking reaction. The amount of tar was reduced by more than 17% in case of brewery spend grain. As well as syngas composition was enriched with CH4, H2 and CO concentration.

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The purpose of this work was to determine the effect of the addition of NH4Cl to oat straw on the evolved gases, kinetic triplet, and thermodynamic parameters of the pyrolysis process at 873 K. A complementary approach allowed to assess the effects of the pyrolysis of chlorine- and nitrogen-enriched biomass. The thermal analysis of biomass was performed for four heating rates (5, 10, 20, and 30 K/min). The doping of NH4Cl in the straw favoured i) carbonisation of the chars, ii) formation of C-N bonds, iii) reduction of evolved CH4 and CO2, and iv) an increase in the mean values of the effective activation energy and all thermodynamic parameters. A group of reactions that best fit the experimental data of the pyrolysis process was selected. It was necessary to use unspecified mechanisms to describe the reaction model, particularly for samples enriched with NH4Cl.

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The global emission of CO2 through fossil fuel combustion is still increasing, which is a major challenge for the international community. An integrated carbon capture and utilisation (ICCU) process with a CaO-based sorbent is a promising alternative to effectively reduce emissions. In this work, a comparative thermodynamic analysis of two CaO-based sorbents (commercial and sol-gel CaO) was performed for one cycle of ICCU. In addition, the influence of temperature was investigated from 600 to 750 °C in terms of the degree of CO2 conversion. Thermodynamic calculations were based on the actual gas composition and developed model, where heat consumption and entropy generation were calculated. The results indicate that the degree of CO2 conversion decreased from 84.6 to 41.2% and from 84.1 to 62.4% for the sol-gel and commercial material, respectively, as the temperatures increased. Furthermore, the total heat consumption during one cycle decreased with higher temperatures. The total amount of consumed heat decreased from 19.1 to 5.9 kJ/g and from 24.7 to 5.4 kJ/g for sol-gel and commercial CaO, respectively. Although commercial CaO always requires more heat during one cycle. Moreover, for both materials, the lowest generation of entropy was calculated at 650 °C with values of 9.5 and 10.1 J/g·K for the sol-gel and the commercial CaO, respectively. At all temperatures, the commercial CaO generated a greater entropy.

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The current COVID-19 pandemic situation and the associated restrictions have increased the amount of generated waste. It results from the necessity to wear personal protective equipment. Thus, the disposal of masks and gloves is a topical issue and requires immediate investigation. The main aims of this work are management and environmental studies of municipal solid wastes (MSW), which have been generated during the COVID-19 pandemic time. Effective waste management in relation to a circular economy is presented. A sample of refuse derived fuel (RDF) with a high content of plastics was used for the experimental and calculation studies. Pyrolysis was selected as the best thermal decomposition process for this kind of wastes. Proximate and ultimate analyses were performed for RDF and its products. Pyrolysis was carried out using a pilot-scale reactor with a continuous flow of 250 kg/h at 900 °C. Thermogravimetric analysis was applied during the pyrolysis investigation and showed that the main decomposition of RDF took place in the temperature range of 250-500 °C. The pyrolysis gas contained combustible compounds like CO (19.8%), H2 (13.2%), CH4 (18.9%) and C2H4 (7.1%), giving a high calorific value - 24.4 MJ/m3. The experimental results were implemented for numerical calculations. Chemkin-Pro software was applied to predict the chemical composition of the pyrolysis gas. The performed computer simulations demonstrated very good agreement with the results obtained during the experiments. They also indicated that there is a strong relationship between the chemical composition of the pyrolysis gas, the process temperature and residence time in the reactor.

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Pyrolysis of the waste organic fraction is expected to be a central element to meet the primary energy demand in future: it increases the impact of renewable energy sources on the power generation sector and allows the amount of waste to be reduced, putting an end to landfills. In the present study, kinetic studies on the pyrolysis of biomass wastes are carried out. Two kinds of industrial organic waste are investigated: brewery spent grain (BSG) and medium-density fiberboard (MDF). The main target of this work is to provide a global equation for the one-step pyrolysis reaction of the investigated materials in an argon atmosphere using isoconversional methods. The conducted analysis allowed to estimate the activation energy as 225.4-253.6 kJ/mol for BSG and 197.9-216.7 kJ/mol for MDF. For both materials nth order reaction was proposed with reaction order of 7.69-8.70 for BSG and 6.32-6.55 for MDF. The developed equation allowed to simulate the theoretical curves of thermal conversion. These curves indicated the highest conversion at the temperature of the degradation of dominant component, which was experimentally verified. By this method, a one-step kinetic model is derived, which can be applied for the reaction kinetics in the CFD modelling of, e.g., pyrolysis and gasification processes.

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The distribution of biomass pyrolysis products under high pressure have rarely been reported. In this study, the effect of pressure on the product distribution of pine sawdust (PS) pyrolysis was studied. The synergistic effect of the side wall rubber (SWR) and PS was confirmed under pressurized conditions. Calcined bottom ash (CBA) and SWR char (SWRC) were used to enhance the quality of the pressurized co-pyrolysis products. The PS and SWR pyrolysis chars obtained under high pressure conditions exhibited serious melting and cross-linking problem. The CO2 content decreased to 19.96 vol% in co-pyrolysis gas with the CBA/SWRC7/3 catalyst. The water content decreased by 85.71% after the SWRC catalyst in the pressurized co-pyrolysis process. Compared with the concentration of benzene in PS and SWR oil, the concentration of benzene in SWR/PS7/3 oil without catalysts increased by 9.57 times and 0.25 times, respectively.

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A novel approach, linking both experiments and modelling, was applied to obtain a better understanding of combustion characteristics of torrefied biomass. Therefore, Pine, Acacia and Miscanthus giganteus have been investigated under 260°C, 1h residence time and argon atmosphere. A higher heating value and carbon content corresponding to a higher fixed carbon, lower volatile matter, moisture content, and ratio O/C were obtained for all torrefied biomass. TGA analysis was used in order to proceed with the kinetics study and Chemkin calculations. The kinetics analysis demonstrated that the torrefaction process led to a decrease in Ea compared to raw biomass. The average Ea of pine using the KAS method changed from 169.42 to 122.88kJ/mol. The changes in gaseous products of combustion were calculated by Chemkin, which corresponded with the TGA results. The general conclusion based on these investigations is that torrefaction improves the physical and chemical properties of biomass.

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In this study, the combustion and pyrolysis processes of three sewage sludge were investigated. The sewage sludge came from three wastewater treatment plants. Proximate and ultimate analyses were performed. The thermal behaviour of studied sewage sludge was investigated by thermogravimetric analysis with mass spectrometry (TGA-MS). The samples were heated from ambient temperature to 800 °C at a constant rate 10 °C/min in air (combustion process) and argon flows (pyrolysis process). The thermal profiles presented in form of TG/DTG curves were comparable for studied sludges. All TG/DTG curves were divided into three stages. The main decomposition of sewage sludge during the combustion process took place in the range 180-580 °C with c.a. 70% mass loss. The pyrolysis process occurred in lower temperature but with less mass loss. The evolved gaseous products (H2, CH4, CO2, H2O) from the decomposition of sewage sludge were identified on-line.

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