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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1/2020

Solid Biofuel Characterization and Ash Properties of Acacia Mangium

Van Minh Duong, Emmanuel Padouvas

Acacia Mangium is a common industrial planted woody biomass in the tropical and subtropical climates. As an economically viable, agroforestry beneficial and environmentally sustainable bio-energy form, it has the potential to generate heat for thermochemical conversion systems. This article provides a comprehensive evaluation of its characteristics, physiochemical properties, ash composition and transformation phenomena. In accordance with the ISO/DIN guides for solid fuels, the standard methods were applied. The results of analyses solid biofuel showed the significant calorific value (19-20 MJ/kg); high volatile matter, relatively low ash content; and a low S content. X-ray analyskjhgis detected high values of Ca, K, Fe, Al and Si the ash-forming elements. Ash softening and fusion phenomena were observed, with heat generated continuously at constant rates (maintained at 550 ± 10 °C for 120 minutes and practically at 850 ± 10 °C for 240 minutes). The first signs of deformation were recorded at a temperature of approximately 1220 °C, with the melting point reached at 1310 °C, which was an advantage for a woody solid biofuel.

Keywords: Acacia Mangium; solid biofuel; wood pellets; ash fusion; ash properties

Effect of low pressure on catalytic methanization using nickel catalyst

Kateřina Vondráková, Veronika Šnajdrová, Veronika Kyselová, Tomáš Hlinčík

An increasing concentration of carbon dioxide in the atmosphere is the driving force of on its utilization in different technological processes. Those processes are CCS (Carbon, Capture and Storage) and in particular in CCU (Carbon, Capture and Utilization). One of the promising CCU processes is the catalytic methanation of carbon dioxide and hydrogen. The catalytic methanation utilizes hydrogen, which can be produced using sustainable renewable energy (wind or solar) with unsteady power production. The main product of the catalytic methanation is a synthetic natural gas, consisting mainly of methane. The synthetic natural gas can be used as a substitute for natural gas in energetic applications. This paper presents results from testing of nickel catalyst (Ni/γ-Al2O3) with a variable mass fraction of nickel. Methanation reaction was tested at temperatures below 450 °C and gauge pressure of 0.5 MPa in a through-flow reactor, with a stoichiometric mixture of hydrogen and carbon dioxide. During experiments, catalytic activity, methane selectivity, hydrogen and carbon dioxide conversion were measured.

Keywords: methanisation, nickel catalyst, CCU
1/2020 - pages 7 - 11DOI: 10.35933/paliva.2020.01.02

Profile composition of defined energy by products at landfill

Petr Buryan, Pavel Donát
A number of new findings can be derived from the data obtained. After the initial drop, the water content stabilized at about 30% wt. This finding is likely to correspond to the groundwater level. An unexpected decrease in its content of about 3 to 5 m to about half of the depths from 12 m can be considered unexpected. The CaO concentration decreases from about 42 wt. % to about 25 wt. % in the first seven meters. At 10 meters, it then rises to around 30% by weight. Leaving aside the possibility that this change could be related to the CaO concentration already in the deposited material, this finding can be attributed to the transport of calcium compounds with leaking water. Similar changes in concentration with deposition depth have been demonstrated for sulphates. However, this unexpected calcium data will be related not only to the dissolution of calcium sulfate but also to the dissolution of other calcium salts. The related Mg compounds will not significantly contribute to this process, since the MgO concentration practically does not change with deposition depth. The same applies to BaO.
In this context, long-term “washing” of carbonates from landfill into groundwater can also be expected. This has not been monitored yet, because it is a non-toxic, not monitored substance.
It is clear from the model study that by-products from the operation of brown coal-fired fluidized bed boilers and using limestone as a desulfurization medium during storage in a landfill chemisorb a significant amount of carbon dioxide from the ambient air. This reactivity should be taken into account in the carbon dioxide balance of energy sources, which is not yet respected.
Keywords: landfill; fuel; composition profile
1/2020 - pages 12 - 17DOI: 10.35933/paliva.2020.01.03

Modeling the desulphurization process while coal combustion in fluid boilers

Petr Buryan

In the article are discussed the basic problems affecting flue gas desulphurisation produced in the fluidized bed boilers burning brown coal. There are compared the effects of temperature, residence time and flue gas composition in the fireplace, characteristic parameters and properties of limestone and dolomites, ratios of limestone and coal and cocombusted biomass and recirculation of by-products. The kinetics and thermodynamics of many reactions are represented here by mathematical and empirical relations.

Keywords: modeling; desulphurisation; coal combustion
1/2020 - pages 18 - 25DOI: 10.35933/paliva.2020.01.04

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