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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Current issue


Waste Plastics Chemical Recycling in the Context of Refining and Petrochemical Industries

Tarig Hussein, Daniel Maxa

Rising demand for plastic materials results in increasing volumes of plastic waste generated globally. This poses a question of waste collection and handling of the growing waste volumes. With quality limitations of reuse and mechanical recycling, especially end-of-life mixed plastic waste is mostly landfilled, incinerated or lost to environment. Thermochemical recycling, especially pyrolysis, has been historically explored as an attractive alternative waste processing method with a potential to valorise the plastic waste into energy, fuels and more recently also chemicals and virgin polymers. Thermochemical plastic waste processing and treatment of the intermediates towards the final products have been found to be studied mostly in isolation. Therefore, this study provides a combined view. Updated state of pilot and demonstration projects is reviewed. Typical characteristics of plastic waste pyrolysis products are introduced and the areas of potential impacts on existing plants are highlighted. In order to address the circularity and economic aspect, a summary of recent relevant LCA and business studies is provided, showing common sensitivity factors and main assumptions used therein. Overall, this review summarizes the background behind the recycling of waste plastics and presents it in context of challenges and opportunities of integration with existing refining and petrochemical infrastructure.

Keywords: Thermochemical recycling, Plastic Waste, Pyrolysis, Steam Cracking, Refining, Process Integration
4/2023 - pages 136 - 154DOI: 10.35933/paliva.2023.04.01

Supercritical CO2 power cycle

Eliška Purkarová, Jakub-Vojtěch Ballek, Alice Vagenknechtová, Jan Berka, Tomáš Hlinčík
The article is focused on summarizing the issue of energy circuits working with supercritical carbon dioxide sCO2. Carbon dioxide is currently coming to the forefront of many research institutions with regard to its possible use in its supercritical conditions, thanks to which higher efficiency and compactness of equipment can be achieved compared to conventional steam-water cycles.
The article describes the basic properties of this medium, including a description of sCO2 cycles (Brayton, Rankine, etc.). Furthermore, the possible use of energy cycles with sCO2 is discussed, especially in solar and nuclear power plants and in power plants burning fossil fuels. In the case of solar power plants, the sCO2 Brayton cycle can offer higher cycle efficiencies than using super-critical steam cycles. The use of sCO2 in nuclear or coal power plants in turn increases efficiency and reduces water consumption. In addition, the use of the sCO2 circuit in new nuclear reactors of the IV generation is currently being considered, in which the operating temperatures are in the range of 500 - 900 °C, i.e. they are generally higher than operating water-cooled reactors.
Even though the use of CO2 refrigerant in power systems has been known for a long time (e.g. use in the first Czechoslovak power plant in Jaslovské Bohunice), they are still not used commercially in the energy industry. One of the reasons is the ongoing research into the behavior of materials at high temperatures in sCO2, corrosion protection, or the effect of carbon dioxide purity on behavior in the supercritical region.
Keywords: energy cycles, carbon dioxide, sCO2, Brayton cycle, nuclear power plant
4/2023 - pages 155 - 165DOI: 10.35933/paliva.2023.04.02

Reduction of sulfur and ash contents from low-rank coal

Sami Ullah, Asad Ullah, Zaheer Ahmed Kasi, Tufail Ahmad, Gaofeng Ren

This research attempted to reduce sulfur and ash content for enhanced coal recovery by the froth flotation technique. Dukki district (Pakistan) coal was upgraded using a flotation technique followed by acid leaching. Tests on flotation concentrate were carried out to improve the grade of coal further. Tests were carried out to investigate and determine the effect of critical parameters like particle size, pH, and pulp density on reducing ash and sulfur content from coal. The particle size was observed to have the most significant role in coal ash and sulfur reduction, followed by the pH, and pulp density, respectively. The optimum particle size, pH, and pulp density values were 74 μm, 9 and 10%, respectively. The results from the flotation study on a laboratory scale at optimized conditions were a 54.1% increase in total carbon, a 42.12% reduction in ash, and a 38.32% reduction in sulfur. Final ash and sulphur contents in clean coal were 15.2% and 1.65%, respectively. Thus, clean coal can preferably be used in power plants and the cement industry in the country.

Keywords: Froth Flotation; Acid Leaching; Pulp density; Sulfur reduction
4/2023 - pages 166 - 171DOI: 10.35933/paliva.2023.04.03

Investigation of the bactericidal-inhibitory property of the reagent in laboratory conditions

Guseyn R. Gurbanov, Aysel V. Gasimzade

The corrosion protection capability of reagent C-1 with bactericidal-inhibitory properties was studied in laboratory conditions in neutral, acidic and alkaline mediums and the concentration of the reagent was in the range of 10-25 mg/l. Desulfomicrobium and desulfovibrio desulfuricans strains of sulphate-reducing bacteria extracted from formation water of oil well no. 1802 of Bibiheybatneft OGPD, SOCAR field were used as the research object. For comparison, reagent free and reagent-based mediums were used in the research process. In laboratory conditions, the effect of reagent C-1 on the incubation period of sulfate-reducing bacteria was investigated for fifteen days in postgate-“B” nutrient medium. It was determined that having a bactericidal property, reagent C-1 affects the life activity of bacteria significantly. It was revealed that the highest bactericidal effect occurs at a concentration of 25 mg/l of reagent C-1 and the effect of corrosion protection from bacteria is 85%.

Keywords: bactericide, corrosion, protection effect, hydrogen sulphide, sulfate-reducing bacteria, neutral medium, acidic medium, alkaline medium
4/2023 - pages 172 - 177DOI: 10.35933/paliva.2023.04.04

The effect of the 2-ethylhexyl nitrate the oxidation stability and the carbon residue of the diesel fuel

Zlata Mužíková, Pavel Šimáček, Miloš Auesrvald, Dan Vrtiška, Jiří Kroufek

2-Ethylhexyl nitrate, also referred to as cetane booster or cetane improver, is now commonly used as a diesel fuel additive to increase cetane number. It is already used in the refinery blending of a final product. It can also be obtained in the form of a supplementary additive for a final consumer. Its positive effect on the cetane number is undisputed and proven, but at the same time, due to the nature of its effect on the combustion process, the measured oxidation stability of diesel fuel may be adversely affected. This negative effect has been observed in the measurement of oxidation stability according to EN 16091 and also in a test simulating long-term storage of diesel fuel, the results of which are presented in this publication. The effect of 2-EHN on the carbonisation residue according to EN ISO 10370 was also studied in the context of monitoring the oxidation stability of diesel fuel with the addition of 2-EHN. In this case, the negative effect of 2-EHN was not demonstrated.

Keywords: 2-ethyl hexyl nitrate, cetane improver, oxidation stability, Petrooxy, carbon residue, diesel fuel
4/2023 - pages 178 - 184DOI: 10.35933/paliva.2023.04.05

technical support editor-in-chief