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Number of results: 5
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Abstract

The influence of sewage sludge torrefaction temperature on fuel properties was investigated. Non-lignocellulosic waste thermal treatment experiment was conducted within 1 h residence time, under the following temperatures: 200, 220, 240, 260, 280 and 300°C. Sawdust was used as lignocellulosic reference material. The following parameters of biochar have been measured: moisture, higher heating value, ash content, volatile compounds and sulfur content. Sawdust biochar has been confirmed to be a good quality solid fuel. High ash and sulfur content may be an obstacle for biochar energy reuse. The best temperature profile for sawdust torrefaction and fuel production for 1 h residence time was 220°C. At this temperature the product contained 84% of initial energy while decreased the mass by 25%. The best temperature profile for sewage sludge was 240°C. The energy residue was 91% and the mass residue was 85%. Higher temperatures in both cases caused excessive mass and energy losses.
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Abstract

In the process of extraction and enrichment of coal waste, considerable quantities of waste material are produced, mainly the gangue and coal sludge, considered as waste or raw material. The main directions of the management development of the waste rock are the production of aggregates, the production of energy products and the liquidation works in hard coal mines and the filling of excavations. The paper proposes the extension of these activities to the use of waste material. The possibility of using aggregates or extractive waste to fill open-pit excavations has been proposed, also in areas within the reach of groundwater and the possibility of building insulation layers of waste material and the production of mixtures of hard coal sludge and sewage sludge to produce material with good energy properties. The analysis was based on the author’s own research and literature data related to selected parameters of waste material. This paper presents our own preliminary studies on the amount of combustion heat and the calorific value of coal sludge combined with other wastes such as sewage sludge. The proposed methods and actions are part of the current directions of development, but they allow the extension of the scope of use of both extractive waste and products produced on the basis of gangue or coal sludge. Due to the frequent lack of the stable composition of these materials, their current properties should be assessed each time before attempting to use them. The fact that it is important to continue research to promote existing economic use and to seek new activities or methods has been concluded.
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Abstract

The aim of the study was to evaluate the effect of pre-sowing seed stimulation of Thuringian Mallow (Lavatera thuringiaca L.) with He-Ne laser light of different exposure times on the crop yield as well as on energetic parameters such as calorific value and combustion heat. Seeds were subjected to laser light with an exposition time of 0, 1, 5, 10, 15 and 30 minutes. Measurements were carried out independently on mature plants from the first and second vegetation year. The results varied between the samples, which indicated possible impact of laser radiation on the resultant weight and calorific value of various experimental combinations. For plants from the second vegetation year the statistical differences in calorific value, combustion heat and crop mass were found between samples characterized by different exposition times: between sample irradiated for 30 min (L30) and 1 min (L1) as well as between sample L30 and sample irradiated for 5 minutes (L5). For plants after the first vegetation year the statistically significant differences in calorific value and combustion heat were found for sample with exposition time of 15 minutes (L15) and control sample, for sample L15 and sample L5 as well as between samples L15 and L30. For all the samples from the second vegetation year the increase in combustion heat and calorific values were detected as compared to control. Thus, after the application of certain parameters of laser radiation to the processing of seeds, the plant can be more useful for energetic purposes through more efficient crop.
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Abstract

The properties, superior calorific value (SCV) and the compressibility factor (z), of 77 natural gas (NG) samples are calculated from two different calibration approaches of gas chromatography, based on ISO 6974-2. The method A uses an analytical curve with seven points that the best adjust is confirmed by Analysis of Variance (ANOVA); it is required when the composition of the natural gas varies. The method B uses a single point calibration, with an allowed tolerance between the calibration gas mixture and sample mole fraction, so it is used to analyze constant natural gas streams. From natural gas composition analyzed by both methods, exceeding the method B allowed tolerance; SCV, z and its uncertainties are calculated and compared. The results show that all samples that comply with Brazilian legislation can be analyzed by method B, because there are no metrological differences in terms of SCV and z, even though the allowed tolerance has been exceeded. This simplified methodology minimizes operator exposure, besides saving about US$ 50,000.00 per chromatograph.
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Abstract

The new legislative provisions, regulating the solid fuel trade in Poland, and the resolutions of provincial assemblies assume, inter alia, a ban on the household use of lignite fuels and solid fuels produced with its use; this also applies to coal sludge, coal flotation concentrates, and mixtures produced with their use. These changes will force the producers of these materials to find new ways and methods of their development, including their modification (mixing with other products or waste) in order to increase their attractiveness for the commercial power industry. The presented paper focuses on the analysis of coal sludge, classified as waste (codes 01 04 12 and 01 04 81) or as a by-product in the production of coals of different types. A preliminary analysis aimed at presenting changes in quality parameters and based on the mixtures of hard coal sludge (PG SILESIA) with coal dusts from lignite (pulverized lignite) (LEAG) has been carried out. The analysis of quality parameters of the discussed mixtures included the determination of the calorific value, ash content, volatile matter content, moisture content, heavy metal content (Cd, Tl, Hg, Sb, As, Pb, Cr, Co, Cu, Mn, Ni, and W), and sulfur content. The preliminary analysis has shown that mixing coal sludge with coal dust from lignite and their granulation allows a product with the desired quality and physical parameters to be obtained, which is attractive to the commercial power industry. Compared to coal sludge, granulates made of coal sludge and coal dust from lignite with or without ground dolomite have a higher sulfur content (in the range of 1–1.4%). However, this is still an acceptable content for solid fuels in the commercial power industry. Compared to the basic coal sludge sample, the observed increase in the content of individual toxic components in the mixture samples is small and it therefore can be concluded that the addition of coal dust from lignite or carbonates has no significant effect on the total content of the individual elements. The calorific value is a key parameter determining the usefulness in the power industry. The size of this parameter for coal sludge in an as received basis is in the range of 9.4–10.6 MJ/kg. In the case of the examined mixtures of coal sludge with coal dust from lignite, the calorific value significantly increases to the range of 14.0–14.5 MJ/kg (as received). The obtained values increase the usefulness in the commercial power industry while, at the same time, the requirements for the combustion of solid fuels are met to a greater extent. A slight decrease in the calorific value is observed in the case of granulation with the addition of CaO or carbonates. Taking the analyzed parameters into account, it can be concluded that the prepared mixtures can be used in the combustion in units with flue gas desulfurization plants and a nominal thermal power not less than 1 MW. At this stage of work no cost analysis was carried out.
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