Browsing by Author "Demirbas A."

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    Cement mixes containing colemanite from concentrator wastes
    (Elsevier Ltd, 1998) Erdoǧan Y.; Zeybek M.S.; Demirbas A.
    In this article, colemanite ore wastes of particle size <25 mm and sludge from concentrator were dried by hot air flow and then were mixed with Portland and trass cements. The effects on the setting and mechanical properties of the colemanite ore wastes mixed with Portland and trass cements were investigated. It was found that some colemanite wastes can be used as cement additives. © 1998 Elsevier Science Ltd.
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    Utilization of volcanic slag in cement industry from Manisa in Turkey
    (2012) Aslan A.; Demirbas A.
    Cement, one of the basic materials of construction engineering, has an important place in view of strength and cost of structure. Cement consumption is increasing parallel to development of building construction sector. For cement producer, minimal cost is desired by using new and economical material source. On the other hand, the controllers and contractors need cheaper, safer and higher strength materials. It is well known that pozzolanics are chemically active silica and alumina bearing materials. There are many different pozzolanic materials. In this study, the volcanic slags from Kula and Gokceoren in Turkey were used as cement additives. The Portland cement clinker and slag were ground together. Normal Portland cement mortar and slag cement mortar were made with a constant water/binder ratio and similar type aggregates. In each slag cement mortar, the slag was 25 percent by weight of cement. The experimental results show that there is a good linear correlation between the Blaine fineness of cement and strengths of mortar. As the fineness of volcanic slag cement increases, the interfacial zone between aggregate and cement paste becomes stronger, as a result both compressive strength increase © Sila Science.
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    Gasoline- and diesel-like products from heavy oils via catalytic pyrolysis
    (Taylor and Francis Inc., 2017) Demirbas A.; Al-Ghamdi K.; Sen N.; Aslan A.; Alalayah W.M.
    Heavy oil is less expensive than light crude oil, but heavy oil is more expensive to obtain light oil products. Conventional light crude oil resources are decreasing, therefore heavy oil resources will be needed more in the future. There are huge differences from field to field for heavy oil deposits. In terms of final productive use, heavy oil is considered as an unconventional resource. Heavy oil upgrading depends on four important factors: catalyst selection, heavy oil classification, process design, and production economics. Heavy and extra-heavy oils are unconventional reservoirs of oil. Globally, 21.3% of total oil reserves are heavy oil. Heavy oil is composed of long chain organic molecules called heavy hydrocarbons. The thermal degradation of the heavy hydrocarbons in heavy oil generates liquid and gaseous products. All kinds of heavy oils contain asphaltenes, and therefore are considered to be very dense material. The most similar technologies for upgrading of heavy oils are pyrolysis and catalytic pyrolysis, thermal and catalytic cracking, and hydrocracking. The amount of liquid products obtained from pyrolysis of heavy oil was dependent on the temperature and the catalyst. Pyrolytic oil contains highly valuable light hydrocarbons as gasoline and diesel components range. The constant increase in the use of crude oils has raised prices of the most common commercial conventional products and consequently seeking for new alternative petroleum resources, like some unconventional oil resources, becomes an interesting issue. The mass contents of gasoline, diesel, and heavy oil in the crude oil are 44.6%, 38.3%, and 17.1%, respectively. The gasoline yield from the heavy oil catalytic (Na2CO3) pyrolysis is higher than the diesel efficiency for all conditions. The yield of gasoline products increases with increasing pyrolysis temperature (from 230°C to 350°C) and percentage of catalyst (from 5% to 10%). The yields of gasoline-like product are from 21.5% to 39.1% in 5% catalytic run and from 32.5% to 42.5% in 10% catalytic run. The yields of diesel-like product are from 9.3% to 29.8% in 5% catalytic run and from 15.5% to 33.7% in 10% catalytic run. © 2017 Taylor & Francis Group, LLC.
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    Calculation of higher heating values of hydrocarbon compounds and fatty acids
    (Taylor and Francis Inc., 2018) Demirbas A.; Ak N.; Aslan A.; Sen N.
    Hydrocarbon compounds are formed by carbon and hydrogen elements. The higher heating values (HHVs) of the hydrocarbon compounds can be calculated based on the carbon (C) and hydrogen (H) contents of the chemical structures. HHVs (MJ / kg) as a function of the carbon (C) and hydrogen (H) fractions of N-saturated hydrocarbons can be calculated by the following equation: HHV = 0.303 (C)+ 1.423 (H) According to this Equation, the HHV is a function of the percentages of the carbon (C) and hydrogen (H) of pure n-saturated hydrocarbon compounds. This Equation represents the correlation obtained by means of regression analysis. It is found that the calculated values shows mean difference of 0.18%. The correlation coefficient is 0.9955. HHVs as a function of the iodine value (IV) and the saponification value (SV) of fatty acids can be calculated by the following equation: HHV(MJ/kg) = 49.43 − 0.015(IV)−0.041(SV). © 2018 Taylor & Francis Group, LLC.