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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General Methods for Fuel Analysis I: Analysis of Ele-ments and Nonhydrocarbon Compounds

Martin Staš, Petr Baroš, Lukáš Matějovský, Hugo Kittel, Pavel Šimáček
This article is the first in a series of articles aimed at introducing common methods for evaluating gaseous, liquid, and solid conventional and alternative fuels. The paper presents an overview of the monitored elements and their non-hydrocarbon compounds for individual liquid and gaseous fuels. Methods for determining these analytes are also presented. The significance of these determinations is also discussed. The emphasis is given mainly on standardized parameters and tests, but in some cases, we discuss also non-standardized tests or analyses not required by standards. The main goal of the article is to provide a comprehensive overview of elements and their non-hydrocarbon compounds monitored for individual fuels, the reason why these analytes are monitored, and what methods are used for this monitoring.
Practically all liquid fuels discussed in this article are monitored for sulfur content. The limit value for sulfur content is 10 mg/kg, with the exception of paraffinic diesel fuel and some synthetic liquid fuels. Phosphorus content is monitored in all fuels containing a higher proportion of biocomponents. Examples such fuels are ethanol, FAME, E85, E95, and rapeseed oil. For fuels containing ethanol, the oxygen content (E5, E10) and alcohol content (E5, E10, E85 and E95), or ether content (E5, E10, E85) are also monitored. Among the minor elements, lead (E5, E10, E95), manganese (E5, E10, B7, and B10), copper (ethanol, E95), alkali metals (FAME) and alkaline earth metals (FAME and rape oil) are monitored.
As with liquid fuels, the sulfur content of gaseous fuels is also monitored. Of the sulfur compounds, the sum of sulfur and carbonyl sulfide content is monitored for CNG, LNG, and their bioequivalents. For LPG for internal combustion engines, sulfane is determined qualitatively, whereas for LPG for heating purposes, the sulfur content is quantified. In the case of LPG for heating purposes, the ammonia content is determined qualitatively, and in the case of biogas according to ČSN 65 6514, the content of nitrogenous impurities except to nitrogen, and the sum of the content of carbon dioxide, nitrogen and oxygen are also evaluated.
2/2023 - pages 37 - 49DOI: 10.35933/paliva.2023.02.01

The Future of the Czech Gas Industry

Karel Ciahotný

In the Czech Republic, the gas industry is a key sector for ensuring the successful growth of industrial production and the growth of the standard of living. However, the set of Green Deal agreements recently adopted by the European Union envisages the gradual reduction of natural gas consumption and its replacement by ecologically produced (green) hydrogen. However, the production of green hydrogen in the Czech Republic is not yet industrially established, and its realisation will require considerable financial sums as investments in the relevant infrastructure. This will be reflected in a significant increase in the price of gas containing the prescribed proportion of green hydrogen. The planned addition of a certain proportion of hydrogen to natural gas will bring a number of complications to the gas industry. Production of a sufficient amount of green hydrogen, which should be added to natural gas, is not ensured in the Czech Republic or in the EU and will require considerable investment in the production infrastructure, which will in the final phase be transferred for the most part to the end consumer of the mixed gas. Total gas consumption will increase by 13%, as hydrogen has three times lower calorific value compared to methane, which is the majority component of natural gas. The reduction in greenhouse gas emissions will therefore be minimal or, taking into account the carbon footprint of the additional equipment needed for hydrogen production, even negative.

2/2023 - pages 50 - 55DOI: 10.35933/paliva.2023.02.02

Low temperature pyrolysis of polylactic acid (PLA) and its products

Olga Bičáková, Jaroslav Cihlář, Pavel Straka
The fact that polylactic acid (PLA) is not biodegradable makes it necessary to find the methods of effective treatment of its waste. A significant method of processing waste PLA can be slow low-temperature pyrolysis, providing mostly oil and energy gas. The PLA pyrolysis provides almost 50 wt.% oil and 21–23 wt.% energy gas with a high carbon monoxide content above 90 vol.% at temperatures up to 420 °C. The temperatures above 420 °C do not give acceptable yields of oil anymore, and at the same time there are higher losses due to the release of low boiling aldehydes and ketones. The obtained oil and gas showed an acceptable calorific value as a basis for their use as substitute fuels. Due to its composition, oil can also be considered as a source of valuable chemicals (tetrahydrofuran, paraldehyde, cyclopentanone and ether) and gas as a source of carbon monoxide for industrial applications and, more recently, for biomedical use. Even plastic waste mixtures with a high proportion of PLA in a 1:1 ratio can be efficiently processed by slow low-temperature pyrolysis. The pyrolyzed mixture showed very similar yields of solid carbonaceous residue and oil (38 wt.% and 35 wt.%). The composition of the solid phase was only minimally different from the low-temperature pyrolysis of PLA. Although the ratio of PLA:LPO components was 1:1, the CO content decreased by ca. 20 vol.% at the expense of CO2 and lighter C2-C5.
2/2023 - pages 56 - 62DOI: 10.35933/paliva.2023.02.03

Properties and Analysis of Liquid Alternative Fuels III: Vegetable Oils and Hydrotreated Vegetable Oils

Martin Staš, Dan Vrtiška, Hugo Kittel, Pavel Šimáček
The importance of alternative fuels and biofuels is constantly growing due to energy security, sustainability, and social responsibility. This article is another in a series of review articles designed to recapitulate information on the required properties of individual alternative fuels, their testing methods, and the significance of individual analyses. This article is focused on fuels based on vegetable oils and hydrotreated vegetable oils.
Rapeseed oil is a triglyceride-based fuel that can be burned in modified diesel engines. Modification of the engine consists in the inclusion of preheating of the fuel or modification of the injection system, due to the high viscosity of this fuel. Rapeseed oil and vegetable oils in general have a higher oxygen content than conventional diesel fuels, which is associated with a lower energy content than that of diesel fuels. Compared to diesel, vegetable oils have a higher density, a lower cetane number, and a significantly higher flash point and viscosity. Vegetable oils also have low oxidative stability. Physical properties monitored in rapeseed oils include density, viscosity, flash point, and calorific value. From the chemical properties, the iodine number, acidity number, water content, calcium, magnesium, sulfur, and phosphorus are monitored. From the other properties, oxidative stability, ignitability, ash content, carbonation residue, content of impurities, and appearance are monitored for rapeseed oils.
HVO is a high-quality fuel for standard diesel engines. Due to the hydrocarbon character of HVO, no engine modification is required. HVO has a very high cetane number, very good low-temperature properties, optimal viscosity, high flash point, excellent oxidative stability, and a very low content of undesirable contaminants such as aromatic hydrocarbons, sulfur, nitrogen, and oxygen-containing compounds. Compared to diesel fuels, HVO has a lower density. The observed qualitative parameters and testing methods are very similar to those of conventional diesel fuel B7. The main difference lies in the modified determination of aromatic hydrocarbons.
2/2023 - pages 63 - 69DOI: 10.35933/paliva.2023.02.04

technical support editor-in-chief