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This article discusses the potential of using computer-simulation methods in processes such as thermal waste conversion, i.e., pyrolysis, gasification, combustion and torrefaction. These methods are gaining in importance, among others, due to the difficulties in execution and high costs associated with conducting experimental research in real conditions or the need to obtain detailed data on the phenomenon under study in a relatively short time. Computer simulation also allows for numerous errors to be avoided, such as those that may occur during optimization activities, the effects of which may have serious consequences, both economic and environmental. In addition to their many advantages, the limitations and disadvantages of using computer-simulation methods were also indicated, mainly related to the interpretation and validation of the results obtained using modelling. Owing to the complexity of the phenomena occurring during thermal conversion, special attention was focused on models based on chemical kinetics, thanks to which it is possible to predict the quantitative and qualitative composition of products in these processes. The aim of this research is to identify the research gap in the field of issues related to models of chemical kinetics of thermal waste conversion processes. [ABSTRACT FROM AUTHOR]

One of the greatest challenges humankind currently faces is global warming, mainly caused by greenhouse gas emissions. Here we have attempted to show how thermal conversion products, specifically from the pyrolysis of biomass wastes such as sewage sludge, can be used effectively and equivalently to sequester CO2 in brownfield and degraded areas. Scenarios were devised that showed the significant potential for CO2 sequestration in the form of biochar from sewage sludge deposited on degraded and brownfield areas. With the current amount of sludge production, such sludge could even be used in its entirety as a raw material in pyrolysis processes, where, in addition to the biochar, the heat necessary for drying the sludge could be generated and high-energy gas and liquid fractions could be obtained, which could be used to produce alternative fuels. It is therefore important to consider both the potential for CO2 sequestration on degraded and brownfield sites and the potential for sludge disposal in Europe as viable options for reducing greenhouse gas emissions and promoting sustainable waste management practices. [ABSTRACT FROM AUTHOR]

This review comprehensively examines biochar, an essential material in an era of climate change for reducing carbon dioxide (CO2) emissions into the atmosphere. It is inconspicuous, black, lightweight, and very porous, and is produced through the thermal conversion of biomass. Our literature review highlights biochar's expansive application possibilities. Firstly, its potential to improve soil quality and sequester CO2 has been examined, as well as its utilization in iron and steel manufacturing to minimize the quantity of coke and ultimately reduce CO2 emissions. In industrial manufacturing, the complete elimination of coke can promote environmental neutrality, which is achieved using biochar from biomass for its extrusion. Furthermore, biochar is becoming increasingly significant in modern energy storage technologies and as an important additive in Pickering emulsions, which are also employed in energy storage systems. Additionally, the use of carbon black is a broad topic, and this review illustrates where it can be successfully utilized, especially in environmentally sensitive areas. [ABSTRACT FROM AUTHOR]

The aim of the article is the offer of control of environmentally undesirable products of coal and biomass co-firing with the use of numerical methods. The article analyzes the impact of co-combustion of coal and pellets made of sunflower husk in power plant boiler with a capacity of 125 MW on the composition of the flue gas. Based on the data obtained from a real object, in particular: the combustion temperature, the reagent fluxes, i.e. air, coal and biomass, as well as the elemental composition of the fuels supplied into the boiler, the initial conditions were formulated and the computer simulations were made, leading to determining the chemical composition of flue gas. Numerical calculations were performed using the latest version of CHEMKIN-PRO software. Chemical mechanism was developed by the Italian group The CRECK Modeling and it included 134 compounds and 4169 chemical reactions, including reactions of forming chlorine compounds. Additionally, the impact of selected parameters, e.g. temperature on the chemical composition changes of the combustion products was analyzed. Developed calculation model with the implemented chemical mechanism was verified by data collected from the real conditions, leading to increasing the reliability of the results. The calculations showed that the most important influence on the composition of the flue gas from the co-firing process of coal with sunflower husk has a composition of biomass. It should be emphasized that the results of computer simulations obtained by the authors have an useful aspect and can be applied in practice, especially to the analysis of the mechanism of chloride corrosion which is possible to occur due to the chlorine content in the biomass. They may also be useful for evaluating the unburned hydrocarbons produced by combustion of rich mixtures (λ < 1.0).

In recent years the numerical modelling of biomass combustion has been successfully applied to determine the combustion mechanism and predict its products. In this study the influence of the addition of waste glycerin in biomass wood pellets on the chemical composition of exhaust gases has been investigated. The pellets have been prepared from spruceand pine wood sawdust without and with addition of waste glycerin. The waste glycerol is a undesirable by-product of biodiesel transesterification at oil manufacturing. The produced pellets were being burned in the 10 kW domestic boiler adapted to wood pellets combustion. The possibilities of pollutants generation (CO2, CO, NOx SOx and compounds containing chlorine) in the exhaust gases coming from the boiler were numerically calculated using the latest version of CHEMKIN-PRO software, introduced by the American company Reaction Design. The results of the calculations correspond to the data obtained on a real object, in particular: combustion temperature, gas pressure, residence time of fuel in the burner, air flow, fuel consumption, as well as elementary composition of fuel supplied into the boiler. The proposed method of predicting the chemical composition of exhaust gases allows proper control of the combustion process and can be considered as an important step in reducing the pollutants (lower emission of NOx, SOx and CO2 neutral) and thus to contribute to the improvement of the environmental quality. In addition, knowledge of the amounts of Clbased compounds produced in combustion process (under given conditions), can serve as an important hint in terms of corrosion prevention of boiler- and chimney steels.

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Our paper investigates the problems of co-combustion of select grades of biomass, i.e. hay, straw, and wood waste, with natural gas. Research comprised both a laboratory experiment and numerical simulations with the use of a professional software application, Chemkin-Pro. The chemical mechanism of co-combustion of biomass with natural gas was described using 224 reactions and 56 chemical compounds. Based on the flow data determined on an experimental stand, the initial conditions were formulated and numerical simulations were performed. As a result of numerical simulations, the detailed chemical composition of combustion gas at the heating chamber outlet was obtained. The investigation has shown that the use of biomass for energy perposes significantly contributes to the reduction of pollutant emissions in flue gas. [ABSTRACT FROM AUTHOR]

The paper presents the results of experiments on the effect of carbon dioxide addition during natural gas air combustion on the concentrations of CO and NOx in the combustion chamber. Numerical simulations were also performed using the Chemkin-Pro program. As part of the presented experiments, an innovative method of introducing carbon dioxide through the central nozzle of a kinetic burner was tested. This technique allows CO2 to be fed directly into the high-temperature zone, thus not hindering the mixing of the fuel with the oxidizer. The tests were carried out for an excess combustion air ratio of λ=1.1, 1.15 and 1.2, respectively, during the addition of CO2 to 15% vol. of oxidizing mixture (air + carbon dioxide). From combustion gas analyses made at a distance of 740mm from the burner outlet in the furnace axis and 20 and 40 mm from the axis, it was found that combustion chamber CO concentrations depended on the amount of CO2 introduced, the distribution of CO2 in the combustion chamber cross-section associated with the CO2 addition method and the excess air ratio. The highest CO concentrations were only noted in the combustion chamber axis with a considerable fraction of added CO2. Based on the computations and experiments it has been confirmed that diluting combustion gas with CO2 delivers a reduction in NOx concentrations. [ABSTRACT FROM AUTHOR]

This paper contains experimental research of NOxreduction in the combustion process with the primary methods, which were applied separately and in combined systems. In addition, the pulsation disturbance (PD) was applied, that is the gas stream was disturbed to increase the intensity of reagents mixing. An experimental stand was built to determine an influence of the following primary methods: air staging, reburning and flue gas recirculation on a reduction of NOxconcentration. Experiments were carried out in three combinations: air staging with reburning, reburning with recirculation and air staging with recirculation. In all these cases, the PD was simultaneously applied. Researches were carried out in a quartz combustion chamber with laboratory equipment enabled to measure all the thermal and the chemical parameters of the process. The simultaneous application of primary methods causes additional increase in NOxreduction in certain systems. [ABSTRACT FROM AUTHOR]