Testing the Bioeconomic Options of Transitioning to Solid Recovered Fuel: A Case Study of a Thermal Power Plant in Slovakia

This paper deals with the state and perspectives of bioenergy development in the context of exploiting the potential of available natural resources. We analyse the economic benefits of transitioning to alternative biofuel within the research task in cooperation with the Vojany black coal power plant. Within the applied methodology, a non-parametric data envelopment analysis method was used to confirm the most economically efficient types of fuels used in the combustion process. The assumption of fuel efficiency was confirmed by testing fuel combustion combinations directly in the power plant. The transition to 100% combustion of solid recovered fuel creates the potential for sustainable production of the analysed power plant and compliance with the current emission values of basic pollutants and new stricter limits, which will be binding in the EU from August 2021. The proposed solutions were analysed by Monte Carlo simulation. An estimate of the economic results achieved by the power plant was simulated, assuming a complete transition to solid recovered fuel. The results of the study support the feasibility of creating a circular waste management market, with the Vojany black coal power plant as the largest user of solid recovered fuel in Slovakia and abroad.

Directional Hydraulic Fracturing (DHF) of the Roof, as an Element of Rock Burst Prevention in the Light of Underground Observations and Numerical Modelling

The following article analyzes the effectiveness of directional hydraulic fracturing (DHF) as a method of rock burst prevention, used in black coal mining with a longwall system. In order to define changes in seismic activity due to DHF at the “Rydułtowy” Black Coal Mine (Upper Silesia, Poland), observations were made regarding the seismic activity of the rock mass during coal mining with a longwall system using roof layers collapse. The seismic activity was recorded in the area of the longwall itself, where, on a part of the runway, the rock mass was expanded before the face of the wall by interrupting the continuity of the rock layers using DHF. The following article presents measurements in the form of the number and the shock energy in the area of the observed longwall, which took place before and after the use of DHF. The second part of the article unveils the results of numerical modeling using the discrete element method, allowing to track the formation of goafs for the variant that does not take DHF into consideration, as well as with modeled fractures tracing DHF carried out in accordance with the technology used at “Rydułtowy” coal mine.

On the possibilities to apply indices of industrial coal-rank classification to determine hazardous characteristics of workable beds

Purpose is to identify behaviour of the graded indices as well as their correspondence to grades, groups, and subgroups of similar coal metamorphic degrees to determine hazardous characteristics of workable beds while mining. Methods. Rank scale and changes in the graded index values help define the coal grades, groups, and subgroups having comparable characteristics as well as ultimate composition of organic mass. Coal ranking involves the intensified metamorphism manifestation in the process of transition from lignite to black coal, and then to anthracite. Findings. Analysis of the total of the fusainized components has shown that coal grading is within less than 10 and more than 69% range. However, in the majority of cases its values are recommended as those being less than 39 or more than 40% which prevents from determination of reliable correlation relationships. Free heaving ratio is considered together with the plastic layer thickness making it possible to determine quantitively only LF, LS, LC, and L grades. In terms of vitrinite response index, being 0.8-1.4%, LS, LC, and L grades may be considered as coal in the central ranking series. The fact supports available changes in the internal structure. Originality. Behaviour of the graded indices of industrial coal-rank classification has been determined to identify hazardous characteristics of workable beds while mining. Practical implications are the possibilities to improve the regulatory system for safe mining of workable beds while determining differences in characteristics of vitrinite coal and fusainized coal.

Life Cycle Performance of Various Energy Sources Used in the Czech Republic

As both the human population and living standards grow, so does the worldwide electricity demand. However, the power sector is also one of the biggest environmental polluters. Therefore, options are currently being sought aimed at reducing environmental impacts, one of the potential tools for which concerns the use of life cycle assessment. This study, therefore, focuses on the most commonly used nonrenewable (black coal, lignite, natural gas and nuclear) and renewable sources (wind, hydro and photovoltaic) in the Czech Republic in terms of their construction, operation, and decommissioning periods. Environmental impacts are assessed via the use of selected impact categories by way of product environmental footprint methodology. The results highlight the potential environmental impacts associated with electricity generation for each of the primary energy sources. Black coal and lignite power plants were found to contribute most to the global warming, resource use, energy carriers and respiratory inorganics categories. On the other hand, the impact on water depletion and resource use, mineral and metals categories were found to be most significantly affected by the production of electricity from photovoltaic power plants. Finally, it is proposed that the results be employed to design scenarios for the future energy mix.

Analisis Batubara Jenis Antrasit di PTBA Berdasarkan Kandungan Volatile Matter dan Kalori

This research Coal is one of the sedimentary fossil fuels that can ignite, is formed from organic sediment, and the remains of plants are then formed through the process of coalification. The main element consists of carbon, hydrogen, and oxygen. The formation of coal has certain conditions and only occurs in certain eras throughout geological history. The carbon age was approximately 340 million years ago. In the Permian Age or the Paleozoic era, 270 million also formed the most productive coal which is almost the entire coal deposit (black coal) in other parts of the earth. In this study we conducted at the Laboratory of PT. Bukit Asam tbk. Observation Results in the Study of Average Volatile Matter 19.11, Max Volatile Matter value 38.34, Min Vollatie Matter value 11.34. And the Average Calorie Result of 7578.5 Kacl / Kg, Max Calorie Value of 8046 Kcal / Kg. In this study, it was proved that coal samples were Anthracite types.

Thermodynamic Model of Silicon Smelting in Ore-Smelting Furnaces

Silicon production by silica-containing raw material reduction by carbon in ore-smelting furnaces (OSF) is a complex pyro-metallurgic process. Silicon is produced in a system consisting of charge, furnace electrodes, air, melt, slag, and gases at temperatures above 2000°C, which generates silicon monoxide and carbide unavoidably. The finished product contains impurities (Fe, Ca, Al, Ti, etc.) in small amounts; however, it is still unknown for sure how impurities, contained in raw materials, behave and interact with each other and with silicon. To analyze the distribution of charge components during smelting, the research team used thermodynamic (mathematical) modeling in Selector software. The constructed four-tank silicon production model describes adequately the process. The assumed tank temperatures correspond to the OSF reaction zones (400°C, 1530°C, 2200°C, and 2000°C). Modeling involves 15 charge-carried elements: quartzite from the Cheremshanskoye deposit, charcoal and black coal, petroleum coke, wood chips, and OSF coal electrodes. According to the model, silicon recovery (with a 97.15 wt% silicon content in the melt) is 75%, which is consistent with literature and production data (AO Kremniy, Shelekhov, Irkutsk Oblast).

INFLUENCE OF TEMPERATURE ON THERMAL CONDUCTIVITY OF BLACK COAL

Экспериментально измерена теплопроводность сухого и влагонасыщенного образцов угля в области температур от 298 до 500 К. Теплопроводность угля увеличивается с температурой и проходит через максимум около 390 К, что объясняется выделением летучих веществ и термическим разложением. Значительная разница в поведении теплопроводности наблюдается до и после термической обработки угля, у которого теплопроводность постепенно увеличивается с температурой без максимума и минимума.