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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The preparation and characterization of mesophase from coal tar pitch

Plevová Eva, Valovičová Věra, Vaculíková Lenka, Ritz Michal, Kaloč Miroslav

This work was aimed at preparation of mesophase from coal tar pitch at different final temperatures. Mesophase was characterized by optical microscopic analysis, thermal analysis and Raman spectroscopy. From the results is evident, that the occurrence of predominantly isotropic homogeneous mass corresponds to lower values of temperatures of maximum oxidation velocity, the occurence of anisotropic texture corresponds to higher temperatures obtained from the DTG curves. Thermal analysis along with microscopic analy-sis confirms the trend of evolution of anisotropic texture depending on the rising temperature. More structured anisotropic texture was found in samples S and V. Both samples were also characterized by a higher distillation temperature for 70 vol.% of the pitch, and a higher viscosity at 100 °C.

2/2015 - pages 26 - 29download PDF file

Determination of Adsorbents Surface Area Using BET and DFT Methods

Lenka Jílková, Veronika Vrbová, Karel Ciahotný

This paper is focused on the determination of surface area and pore size distribution for selected sorbents using BET and DFT methods. Adsorption processes are used in various fields, e. g. medicine, environmental protection, pharmaceutical industry. The carbonaceous materials and zeolites belong to most important adsorbents. These sorbents are used to the waste water and waste gas treatment, air drying, e.g. Adsorption process is also used to the biogas treatment very often (removal of sulphur compounds, siloxanes, water or carbon dioxide). Suitable adsorbent is chosen according to the adsorption capacity, selectivity, surface area, pore distribution, regeneration ability and cost. The obtained results showed that adsorbents based on activated carbon had highest surface area for both methods. Sorbents based on activated carbon and the combined adsorbent Envisorb B+ reached higher surface area for DFT method, there was a small difference between methods for silica materials, the activated carbon SC40 reached higher surface area for BET method and zeolites reached double surface area for DFT method. Using argon like adsorptive instead of nitrogen changed surface area for DFT method.

2/2015 - pages 30 - 35download PDF file

Fluidized bed incineration of dry stabilized sewage sludge from the wastewater treatment plant Brno

Michael Pohořelý, Tomáš Durda, Jaroslav Moško, Boleslav Zach, Karel Svoboda, Michal Šyc, Zdeněk Beňo, Petra Kameníková, Michal Jeremiáš, Jiří Brynda,
The article summarizes the results of the combustion test of dry, stabilized sewage sludge from the wastewater treatment plant Brno – Modřice in the fluid-ized-bed reactor with a stationary bubbling bed. The results of the combustions test bring infor-mation about the composition of the flue gas under practical combustion conditions and conver-sions/concentrations of S, Cl and F compounds in the flue gas.
The average CO concentration in the flue gas was 16 mg.m-3, and amount of unburnt carbon in ash was 0.029 wt. % (based on dry fuel), which with regard to the size of equipment and the low freeboard temperature indicates good quality of the combustion process and appropriate fuel dispersion/mixing in the fluidized bed.
The average content of NOx in the flue gas was 1618 mg.m-3, exceeding the legal limits eight times. The average content of SO2 in the gas was 1817 mg.m-3, exceeding the legal limit (Decree No. 415/2012 Coll.) 36 times.
The average content of the dust in the flue gas (62 mg.m-3) behind the hot cyclone was several times higher than the legal limit.
The average content of HCl (11 mg.m-3) in the flue gas was also much higher than the legal limit. Similarly the content of HF (8 mg.m-3) exceeded the legal limit eight times.
N2O content was acceptable and the average value corresponds to the low content of CO in the flue gas.
The results indicate that the reduction of concentra-tions of the monitored pollutants to the values required by the Decree No. 415/2012 Coll. cannot be attained only by primary measures in units for incineration of dry stabilized sewage sludge with heat utilization.
2/2015 - pages 36 - 41download PDF file

Effect of asphaltenes on structure of paraffin particles in crude oil

Petr Vozka, Petr Straka, Daniel Maxa

During the transportation and storage of crude oil at low temperatures, asphaltenes and paraffin compounds leave deposits that can cause problems and are expensive to remove. We investigated the effect of an increased amount of asphaltenes on the content and the size distribution of paraffin particles in samples of crude oil. Two sets of Azeri Light crude oil samples were used: the one set contained the standard asphaltene content of 0.035 wt.%; the other set was enriched with asphaltenes in propane asphalt form until the final asphaltene content was 0.35 wt.%. Both sets were thermally treated in an autoclave at different temperatures (40, 60, 80, 100 °C) for one hour to eradicate their thermal history. Afterwards, the samples were cooled down to 10 °C, and polarized light microscopy was used to record image data about paraffinic particles present in the samples. Image analysis confirmed our theory that the samples with a tenfold higher asphaltene content had significantly reduced amounts of paraffin particles, which were also smaller in size. The effect of asphaltene concentration on the paraffin particles was dependent on the applied temperature. Our results suggest that the asphaltene addition could affect the deposit formation in crude oil, as well as improving its low-temperature properties.

2/2015 - pages 42 - 47download PDF file

The Use of High-Sulphur Fuel Oils as a Marine Fuel

A. Vráblík, N. Bringlerová, J. M. Hidalgo, R. Černý
Although the Czech Republic is not a coastal state, the high-sulphur fuel oils which are produced there have a great potential for application in the field of marine fuels. The issue of marine fuels has gone through dramatic changes recently. This work deals with detailed overview of the overall situation, including the current legislation connected with the maximum permitted sulphur content. The latest trends to achieve the required characteristics with regard to the lack as well as the high price of low-sulphur marine fuel are mentioned. The problematic of qualitative changes in the fuel oils that can take place during the long term storage is discussed as well. Furthermore, the new method for the identification of the incompatible fuel oils is presented. The problems with stability could be prevented using this method.
2/2015 - pages 48 - 53download PDF file


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