Paliva (Fuels) is a scientific journal issued quarterly by the Faculty of Environmental Technology, ICT Prague. Fuels publishes papers on a broad range of topics covering exploitation, processing, upgrading, and utilization of various types of fuels, and power engineering.
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Textural properties and organic matter in sediments from a hard coal mine landfill

Daniela Řimnáčová, Dominik Vöröš, Lujza Medvecká, Eva Geršlová

Textural properties as micropore surfaces and sorption capacity, chemical and technological analyses of sediments collected in the Lazy coal mine landfill (Upper Silesian Coal basin) are presented. The adsorption capacities together with net calorific values (Qid) and total organic carbon (TOC) decreased in the direction of flow while the ash content (Ad) increased. The samples with the highest TOC content have a relatively beneficial Qid and for residual coal particles from coal mining, were comparable with the Qid values of brown coal. The sorption capacity increased with increasing micropore content and correlated with higher levels of TOC. The sorption capacity decreased with distance from the saline water input. These materials play a significant role in the self-cleaning of mine water in-situ.

Keywords: adsorption, organic matter, coal sediments
2/2021 - pages 30 - 34DOI: 10.35933/paliva.2021.02.01

Degradation of nickel-based alloys for precise casting in high-temperature gas environment

Jan Berka, Jana Petrů

The corrosion resistance of the alloys designed for precise casting Inconel 713LC and Inconel 738 in high temperature gas environment were tested. The environments during tests simulated helium coolant of advanced gas cooled reactors and high temperature carbon capture storage environment (CO2). The specimens were exposed in helium containing 500 vppm CO, 100 vppm CH4, 100 vppm H2 a 10 vppm H2O at 900 °C for 1000 hours and in CO2 at 900 °C during 200 hours. After exposure weight changes were investigated, the corrosion damage was observed by optical and electron microscope, the samples exposed in CO2 were investigated by XPS (X-ray Photoelectron Spectroscopy), GD-OES (Glow Discharge Optical Emission Spectrometry). After exposure in helium, 2 types of scales with different composition were observed on the sample surface. The depth corrosion damage was up to 20 μm, on the alloy Inconel 738 was deep corrosion damage only local, on the alloy Inconel 713LCcontinuous. After exposure in CO2 the surface corrosion layer was compact and almost uniform, corrosion interfered up to 30 μm under the surface layer. In high temperature helium, the alloy Inconel 738 could be said to bo more corrosion resistant than Inconel 713LC. In high temperature CO2 both tested alloys performed almost the same corrosion resistance.

Keywords: Inconel 713LC, Inconel 738, high-temperature corrosion, helium, HTR, CCS
2/2021 - pages 35 - 41DOI: 10.35933/paliva.2021.02.02

Hydrogen for transport

Kateřina Vondráková, Tomáš Hlinčík
In recent years, efforts to use environmentally friendly resources and minimizing environmental impacts throughout the life cycle of products. The important point is that greening and reducing emissions from energy industry and transport. If we focus on emissions from transport, these are mainly CO2, NOx and particulate emissions. These emissions arise mainly from the use of fossil fuels. In the transport sector, local CO2, NOx and particulate emissions can be reduced by introducing hydrogen mobility that does not produce these emissions and can be based on renewable energy sources. The contribution shows that the overall efficiency of the conversion of chemical energy into mechanical energy of the vehicle wheel movement, the socalled Well to Wheel (WtW) is the highest in the case of petroleum fuels (84%). The lowest efficiency WtW is in the case of hydrogen produced from water electrolysis. When assessing the overall efficiency WtW (fuel and utilization) is the highest value (18–21 %) in the case of a combination of fossil fuel and the combustion engine. The lowest value of the total efficiency is for the combination of hydrogen produced by electrolysis of water and the combustion engine (3–5 %).
Keywords: hydrogen; transportation fuel
2/2021 - pages 42 - 49DOI: 10.35933/paliva.2021.02.03

Marine fuels after 2020 III

Dominik Schlehöfer, Aleš Vráblík, Radek Černý

On 1st January 2020, a drastic change came into force to reduce the maximum permitted sulphur content of marine fuels from 3.5 % wt. to 0.5% wt. for the deep sea and oceans. This change had an impact not only on the shipping industry, but also on the entire refining sector, be it oil marketers, refineries, traders and manufacturers of fuels and end-user additives. In 2017 and 2018, the situation regarding marine fuels and the impending IMO 2020 changes was mapped out in the articles "Marine Fuels Post-2020" and "Marine Fuels Post-2020 II" published in Paliva journal. These publications are directly followed by the present article, which summarises the current data (as of early 2021) and experience from the past year, the first year of implementation of IMO 2020. The article describes how vessel operators have coped with this drastic reduction of the maximum sulphur content of marine fuels, as well as the economic consequences of this change.

Keywords: marine fuels; IMO 2020; SECA; sulfur content; economic impacts
2/2021 - pages 50 - 58DOI: 10.35933/paliva.2021.02.04

Thermal hydrolysis to enhance energetic potential of sewage sludge: A review

Anna Mágrová, Pavel Jeníček

Sewage sludge biomass is a renewable energy source commonly produced by anaerobic digestion (AD). However, the limited biodegradability of sewage sludge causes a poor energy conversion of organic material into biogas and requires further enhancement. One possible solution is sludge disintegration by a thermal hydrolysis process (THP) that has already proven to enhance biogas production and improve the quality of digested sludge. This article reviews possible THP configurations, such as THP-AD, ITHP, and PAD-THP, together with different input materials and their impact on the energy balance of the wastewater treatment plant (WWTP). Data from full-scale THP demonstrate differences between the configurations and input material. Moreover, the general advantages and disadvantages of THP integration are summarized and presented as a multicriteria analysis that simplifies the decision-making whether the THP should be integrated in the WWTP.

Keywords: Biogas production; dewaterability; energy balance; sludge disintegration; thermal hydrolysis
2/2021 - pages 59 - 68DOI: 10.35933/paliva.2021.02.05



In the article Buryan P.: Biofuel-based pellets, which appeared in the fourth issue of the journal Paliva (Paliva 12, (2020), 4, pp. 181-188), the name of the co-author was incorrectly omitted.The name of the missing co-author is Diana Sedláčková; she should have been listed as the second in the list of authors.

2/2021 - pages 69 - 69DOI: 10.35933/paliva.2021.02.06

technical support editor-in-chief