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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3/2019

Dairy packaging landfill and greenhouse gas emissions

Petr Buryan, Tomáš Hlinčík

From the obtained laboratory knowledge, it is possible to derive the amount of hydrogen generated from the behaviour of disposable packaging of commonly consumed dairy food products containing aluminium, which are currently disposed of in an untreated form by landfilling or incineration in power plants of different output, including domestic furnaces as by-products in landfills bodies, due to their economic demands. This is transformed by the action of methanogenic bacteria into biomethane, which, when released from landfills, contributes significantly to the greenhouse effect. The data obtained show that these disposable municipal wastes should not be disposed of by the currently applied procedures, but should be replaced by other materials or, in many cases, adjusted to their size, shape and especially their weight.

3/2019 - pages 63 - 70download PDF file

CO2 capture by hydrothermally altered ashes

Barbora Miklová, Marek Staf

The study presented here focuses on the alarming increase in carbon dioxide emissions produced by stationary sources combusting solid fossil fuels (black coal, lignite etc.). Various technologies can be used in order to separate carbon dioxide from flue gas. Among them adsorption has been frequently declared as highly promising. This method is based on CO2 capturing inside a porous structure of the inorganic or organic solid material (adsorbent). In principle, adsorption can be realized in two ways: low temperature process, where physical adsorption is more pronounced, or irreversible high temperature capture, where chemisorption is more involved. This study describes a method for preparing zeolites from power plant fly ashes and evaluation of their properties for low temperature CO2 sorption. Power plant fly ash is a material generated by combustion of fossil fuels in electricity production, and after separation it has only limited use and is usually disposed as a waste. Zeolites were synthesized in the samples by a two-step process in which melting of the raw material with a defined amount of sodium hydroxide was followed by wet processing of the intermediate. Alternatively, the process involving only the hydrothermal phase was tested. As a next step in the work, the products were tested in a flow-through laboratory apparatus determining their maximum sorption capacity.

The experiments were performed at atmospheric pressure in a stream of pure CO2 under different temperature conditions (isotherms at 20, 30 and 40 °C).
3/2019 - pages 71 - 77download PDF file

Gaseous emissions in automatic residential heating appliance using rice husks as solid biofuel

Van Minh Duong, Ursula Flener

The experimental work extended recent empirical information on rice husks in conventional thermochemical applications. These agriculture residues were characterized as the potential solid biofuel option with considerable net heating value of 15800 kJ/kg and observed first sign of ash deformation at the temperature of 1450 °C. A commercial residential heating unit with automatic pelletized fuel loading and horizontal flue gas outlet was assembled as the test appliance. Major components in flue gas stream during steady-state operations confirmed typical emission fluctuating profiles of solid biofuel in residential heating appliance. Mean values of carbon dioxide (CO2), carbon monoxide (CO), nitric oxide (NO), sulfur dioxide (SO2), total organic carbon (TOC) and particulate matter (PM) were summarized referred to 13% oxygen (O2) in standard reference conditions or energy content of fuel (mg/MJ). The obtained emission profiles highlighted distinct correlations between volume fractions of gaseous components depending on the elemental contents presented in rice husks. Particulate matters emitted containing unburnt carbonaceous solid and inorganic material remained as by-products showed significant high mass concentrations due to the poor combustion conditions in small-scale installation agreed with earlier work. The intermittent and short maintained steady-states caused by extensive rice husks ash agglomeration occurred on the fire chamber and ashtray were remarked for further investigation.

3/2019 - pages 78 - 86download PDF file

Gas deposits from pipeline cleaning as an indicator of the pipeline condition

Tomáš Hlinčík, Daniel Tenkrát, Pavel Šimáček

Cleaning of pipelines is standard operation prior to internal inspection of gas pipelines performed regularly by all transmission system operators and very often also by distribution system operators. Internal inspection performed by intelligent inspection tools is important procedure which identifies e.g. material loss, corrosion or cracks in pipeline system. However, also liquid or solid deposits, obtained during pipeline cleaning, can provide much information on pipeline condition and can help its operator with identification of possible problems and its sources. Samples of pipeline deposits were studied using various procedures and techniques. First, the ratio of volatile compounds and the ash content were determined. In the next step, elementary analysis of inorganic fractions of the samples was carried out and water content in liquid fractions was determined. The study on the origin of oilfractions was also carried out. The results obtained indicated that studied deposits consisted mainly of inorganic products such as corrosion residues of steel piping accompanied by other minor elements. The liquid fractions of studied samples were complex hydrocarbon mixtures with a significant ratio of turbine oil from compressor stations. The typical composition varied between 60-90 % of turbine oil and 10-40% of higher hydrocarbons (gasoline). The water content identified in samples was in all cases in trace levels.

3/2019 - pages 87 - 93download PDF file

Influence of conditions of rapeseed oil hydrotreating on the products quality

Veronika Váchová, Petr Straka, Anastasia Malysheva, Josef Blažek
Hydrotreating of rapeseed oil was performed using sulphidic Ni-Mo/-Al2O3 catalyst. Six product sets were prepared at WHSV (Weight Hourly Space Velocity) 2.0 h-1, reaction pressures 4 and 8 MPa and reaction tem-peratures 320; 340 and 360 °C. The influence of the re-action conditions on products composition and their physico-chemical properties was studied.
Under all tested reaction conditions, full deoxygenation of triglycerides was achieved. The yield of the liquid organic phase (after water separation) was about 82 wt. % and it was almost the same for all reaction conditions. Water yield was about 6 wt. % and the yield of gaseous product was around 14 wt. %.
The gaseous products consisted mainly of CO, CO2 and propane, in addition to hydrogen, which was used in large excess in the process. The CO yield was lower in case of higher reaction temperatures and higher pressure, and completely opposite behaviour was observed for CO2. This was probably due to the fact that both higher reaction temperature and pressure supported the course of hydrodecarboxylation reactions at the expense of hydrodecarbonylation reactions. The yields of other gaseous products, consisting mainly of methane, ethane, C4 and C5 saturated hydrocarbons, slightly increased, as the reaction temperature and pressure increased.
The higher reaction temperature and lower pressure promoted cracking and isomerization reactions. It resulted in increased yields of shorter C10 - C16 n-alkanes and isoalkanes. On the other hand, higher pressure and lower reaction temperature promoted hydrodeoxygenation reactions, as was evidenced by increasing yields of C18 n-alkane.
All liquid organic products of hydrotreating of rapeseed oil showed very similar kinematic viscosity. The density of these products only slightly decreased with increasing reaction temperature and the reaction pressure did not affect the density significantly. The cetane index of all liquid products was not affected by reaction condiitions and exceeded 100 due to the high content of n-alkanes. The values of CFPP (Cold Filter Plugging Point) were always very high (around 20 °C) due to the high content of n-alkanes in liquid products. The viscosity and cetane index met requirements of the standard ČSN EN 590 for diesel fuel in contrast to density and CFPP.
Selected liquid products of hydrotreating of rapeseed oil were mixed with a mixture of hydrotreated petroleum distillates to simulate their addition to diesel fuel. The contents of 10; 20 and 30 wt. % of hydrotreated rapeseed oil in resulting mixtures were tested. The basic physico-chemical properties of the prepared mixtures (including the mixture of hydrotreated petroleum distillates itself) were subsequently compared with the values required by the standard ČSN EN 590 for diesel fuel. With increasing content of hydrotreated rapeseed oil in the final mixture, the density decreased and the cetane index increased. The mixtures with 20 wt. % of hydrotreated rapeseed oil showed unexpectedly the lowest values of CFPP. The values of all selected physico-chemical parameters of all prepared mixtures were in accordance with the requirements of the standard ČSN EN 590 for diesel fuel. However, with a further increase of the content of hydrotreated rapeseed oil, the density of the resulting mixtures would probably no longer reach the minimum value in this standard, only if the used petroleum distillates for mixing will have higher density, than which were used for these experiments.
The obtained results show that the hydrotreating of rapeseed oil can be performed with sulphidic Ni-Mo/-Al2O3 catalyst at a reaction temperature of 320 °C, the pressure of 4 MPa and WHSV of 2.0 h-1 to achieve fully deoxygenated products. It results in a high-quality renewable hydrocarbon mixture that can be blended into diesel fuel up to 30 wt. %.
3/2019 - pages 94 - 100download PDF file

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technical support editor-in-chief