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Öğe Acetic Acid Leaching of Magnesia From Magnesite via Calcination(Natl Inst Science Communication, 2006) Demirbaş, AyhanIn this study, magnesite mineral was First calcinated between 800-1100 K for all hour and dissolved in acetic acid Solutions. The effects of temperature, solid-to-liquid ratio, reaction time, stirring speed and acid concentration oil the dissolution rate of magnesia in acetic acid were investigated. It was observed that the dissolution of magnesia increased with increasing temperature, stirring speed, reaction time and acid concentration and decreased with increase in solid-to-liquid ratio. The dissolution process is controlled by pseudo first-order reaction rate. Activation energy for the reaction was calculated as 8.78 (kJ/mol).Öğe Adsorption of Cu(II), Zn(II), Ni(II), Pb(II), and Cd(II) from aqueous solution on amberlite IR-120 synthetic resin(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2005) Demirbaş, Ayhan; Pehlivan, Erol; Göde, Fethiye; Altun, Türkan; Arslan, GülşinThe adsorption of copper(II), zinc(II), nickel(II), lead(II), and cadmium(II) on Amberlite IR-120 synthetic sulfonated resin has been studied at different pH and temperatures by batch process. The effects of parameters such as amount of resin, resin contact time, pH, and temperature on the ion exchange separation have been investigated. For the determination of the adsorption behavior of the resin, the adsorption isotherms of metal ions have also been studied. The concentrations of metal ions have been measured by batch techniques and with AAS analysis. Adsorption analysis results obtained at various concentrations showed that the adsorption pattern on the resin followed Freundlich isotherms. Here we report the method that is applied for the sorption/separation of some toxic metals from their solutions. (C) 2004 Elsevier Inc. All rights reserved.Öğe Analysis of petroleum coke from low grade oily sludge of refinery(TAYLOR & FRANCIS INC, 2018) Demirbaş, Ayhan; Acar, Şükrü; Horasan, Bilgehan Yabgu; Alalayah, Walid M.Petroleum coke is often shortened as pet coke. Petroleum coke or pet coke is a product obtained from oil of all kinds during the oil refining process. Petroleum coke is a carbon-rich solid originating from petroleum refining and is obtained by cracking process. Petroleum coke is a byproduct of the coking unit, a residual fuel upgrader. The coke quality depends on the crude oil processed in refinery. The mixture of oil, solids and water deposited at the bottom of the storage deposit is known as waste oil sludge. Oil sludge is one of the solid wastes produced in petroleum refinery and it is a complex emulsion composed of various petroleum hydrocarbons, heavy metals, solid particles, and water. As a result of the refining process of crude oil, the contaminated sludge is biodegraded and converted into waste products that damage the environment and human health. In the coke processing, the assessment of oil sludge fraction is based on the principle of heating to high temperatures and the removal of light fractions from the breakdown. If the oil sludge initially contains low levels of sulfur and metal, the resulting petroleum coke is then calcined before use. The high quality needle type coke produced on convenient conditions in the coking unit.Öğe Biodesulfurization of Cayırhan Lignites(Taylor & Francis Inc, 2006) Gürü, Metin; Çubuk, Meltem; Dursun, Şükrü; Demirbaş, AyhanIn this study, the lignite was improved oxidizing sulfur compounds by Thiobacillus thiooxidans and Thiobacillus ferrooxidans bacteria. Experiments in the batch reactors have been carried out 20% aqueous suspension of coal samples. Sugar beet molasses was used as the bacterial substrate. The maximum removal of combustible sulfur was obtained as 78.2% under the following conditions; addition 5% of T. thiooxidans and 5% T. ferrooxidans into coal suspension, 0.2 g molasses/g coal change, pH value of 3, at shaking rate of 70 rpm and at 40 degrees C for 5 days.Öğe Biodiesel Production via Non-Catalytic Scf Method And Biodiesel Fuel Characteristics(Pergamon-Elsevier Science Ltd, 2006) Demirbaş, AyhanVegetable oil (m)ethyl esters, commonly referred to as "biodiesel," are prominent candidates as alternative Diesel fuels. Biodiesel is technically competitive with or offers technical advantages compared to conventional petroleum Diesel fuel. The vegetable oils, as alternative engine fuels, are all extremely viscous with viscosities ranging from 10 to 20 times greater than that of petroleum Diesel fuel. The purpose of the transesterification process is to lower the viscosity of the oil. Transesterifications of vegetable oils in supercritical methanol are performed without using any catalyst. The most important variables affecting the methyl ester yield during the transesterification reaction are the molar ratio of alcohol to vegetable oil and the reaction temperature. Biodiesel has become more attractive recently because of its environmental benefits. The cost of biodiesel, however, is the main obstacle to commercialization of the product. With cooking oils used as raw material, the viability of a continuous transesterification process and recovery of high quality glycerol as a biodiesel by product are primary options to be considered to lower the cost of biodiesel. Supercritical methanol has a high potential for both transesterification of triglycerides and methyl esterification of free fatty acids to methyl esters for a Diesel fuel substitute. In the supercritical methanol transesterification method, the yield of conversion increases to 95% in 10 min. The viscosity values of vegetable oils are between 27.2 and 53.6 mm(2)/s, whereas those of vegetable oil methyl esters are between 3.59 and 4.63 mm(2)/s. The flash point values of vegetable oil methyl esters are much lower than those of vegetable oils. An increase in density from 860 to 885 kg/m(3) for vegetable oil methyl esters or biodiesels increases the viscosity from 3.59 to 4.63 mm(2)/s. Biodiesel is an environmentally friendly fuel that can be used in any Diesel engine without modification.Öğe Biofuel Based Cogenerative Energy Conversion Systems(Taylor & Francıs Inc, 2006) Demirbaş, AyhanThe goal of this study is to investigate how co-operation between industry and district heating companies can improve profitability of biofueled cogenerative investments in small to medium-sized applications. Currently advanced biomass gasification and gas turbine combined cycle has been found to be a promising cogenerative conversion technology for the recovery of heat present in biomass fuel. Increased biofuel based cogenerative power production in the future is clearly dependent on the improvement of both performance and investment costs of new high performance technology, and on the nature of policy instruments designed to promote the technology. The use of biofuels for cogeneration on a large scale is focused mainly on forest industry sites, where considerable quantities of biomass are available. While cogeneration provides several environmental benefits by making use of waste heat and waste products, air pollution is a concern any time fossil fuels or biomass are burned.Öğe Biogas Potential of Manure and Straw Mixtures(Taylor & Francıs Inc, 2006) Demirbaş, AyhanWheat straw or manure or both were converted to a methane-rich gas mixture. Anaerobic biomethane production is an effective process for conversion of a broad variety of lignocellulosic materials to methane to substitute natural gas and medium calorific value gases. Methane generating bacteria (methanogens) and other microbes help digest dying plants in anaerobic (without oxygen) conditions. Wheat straw wastes represent a potential energy resource if they can be properly and biologically converted to methane. The yields of methane front the materials used were found between 10.4% and 14.7%. The producing gas has an energy, content of about 33%-50% of the higher heating value from the feedstock. The most important parameters for the biogas generation rates were the total solids (TS) concentration in the slurry, the digestion time, species of feeding substrate, and pH of the medium. The methane content of the biogas was in the range of 73%-79% for the runs, the remainder being principally carbon dioxide.Öğe Biomass Gasification for Power Generation in Turkey(Taylor & Francıs Inc, 2006) Demirbaş, AyhanIn this study, different biomass gasification applications and strategies that affect the gasifier which makes electricity in Turkey were investigated. Gasification technologies provide the opportunity to convert renewable biomass materials into clean fuel gases or synthesis gases. These gaseous products can be burned to generate heat or electricity, or they can potentially be used in the synthesis of liquid transportation fuels, hydrogen, or chemicals. Gasification offers a combination of flexibility, efficiency, and environmental acceptability that is essential in meeting future energy requirements. The future of biomass electricity generation lies in biomass integrated gasification/gas turbine technology, which offers high-energy conversion efficiencies.Öğe Biomass-Based Combined Heat and Power Systems(Taylor & Francıs Inc, 2006) Demirbaş, Ayhan; Ürkmez, AbdullahThis study aims to identify and evaluate the biomass utilization options and evaluate the sustainable biomass production for combined heat and power (CHP) in Turkey. The total biomass energy potential of Turkey is about 32 Mtoe. The amount of usable biomass potential of Turkey is approximately 17 Mtoe. Among the biomass energy sources, fuel wood seems to be one of the most interesting because its share of the total energy production of Turkey is high at 21%. The use of biofuels for CHP on a large scale is focused mainly on forest industry sites, where considerable quantities of biomass are available. Biomass available for energy can be converted to different types of final energy (e.g., electricity, heat), of these, the production of electricity appears to be particularly important. While CHP provides several environmental benefits by making use of waste heat and waste products, air pollution is a concern any time fossil fuels or biomass are burned.Öğe Chemical analyses of shale gas and conventional natural gas(TAYLOR & FRANCIS INC, 2018) Demirbaş, Ayhan; Çek, Nurettin; Acar, ŞükrüShale gas is essentially non-traditional natural gas (NG). Shale gas can be considered an unusual alternative energy source. Shale gas production is a method of obtaining the NG trapped between deep underground rocks. Shale gas production is not economical, except for horizontal drilling and hydraulic fracturing methods. Advanced analysis of shale gaseous samples can be done using gas chromatography, mass spectrometry and other modern testing methods. The Orsat apparatus includes three absorption pipettes containing chemical solutions that absorb gases. Absorbents are a 33% by weight aqueous solution of potassium hydroxide (KOH) for carbon dioxide (CO2), alkali pyrogallol for oxygen (O-2) and ammoniacal cuprous for carbon monoxide (CO) measurement. Oxygen is absorbed in alkaline pyrogallol or in a chromous solution. Shale gas can be analyzed best gas chromatographically. The capillary column can be separated from all the hydrocarbons and their isomers by alumina, which is used as a stationary phase in the gas chromatographic column, because alumina is highly selective for hydrocarbons. Silica is a specific adsorbent that exhibits greater applicability for hydrocarbons. The chemical contents of shale gas are similar to those of the conventional NG. The processing, transfer and storage and distribution of shale gas are assumed to be similar to the conventional NG.Öğe Contribution of Konya Plain Projects to the National Development in Turkey’s Water-Related Energy(Multi Science Publ Co Ltd, 2006) Berktay, Ali; Nas, Bilgehan; Demirbaş, AyhanKonya basin is the largest closed basin in Anatolia. Konya plain project (KOP: Konya Ovasi Projeleri in Turkish) is a comprehensive group of projects, which includes construction of dams, hydroelectric power plants, and irrigation systems as well as providing developments in agricultural infrastructure, transportation industry, water supply, water budged, environmental impacts and in other issues. The KOP is described as being the second big project for the purpose of irrigation after South Eastern Project in Turkey. The KOP comprises 47,720 km(2) of area spread over four river basins in Konya closed basin. The KOP consists of 12 projects including nine big scale water projects, two water supply projects, energy projects, and a number of small scale surface, and ground water irrigation projects. The KOP area covers the 73% of the total area that can be irrigated in Konya closed basin. Presently, 308,073 ha of land are irrigated by 12 individual projects in the KOP. In order to reach up to 617,923 ha irrigated area, much effort has been done in the all projects.Öğe Desulfurization of Organic Sulfur From Lignite by an Electron Transfer Process(Taylor & Francis Inc, 2006) Demirbaş, AyhanThis study is an attempt to desulfurize organic sulfur from lignite samples with ferrocyanide ion as the electron transferring agent. Effect of temperature, particle size and concentration of ferrocyanide ion on desulfurization from the lignite samples has been investigated. The desulfurization process has been found to be continuous and gradually increases with increase of temperature from 298 to 368 K. The particle size has no significant impact on sulfur removal from the lignite samples. Particle size has no profound impact on the amount of sulfur removal. The desulfurization reaction has been found to be dependent on the concentration of potassium ferrocyanide. Gradual increase in the concentration of potassium ferrocyanide raised the magnitude of desulfurization, but at a higher concentration, the variation is not significant.Öğe Effect of Temperature on Pyrolysis Products From Four Nut Shells(Elsevier Science Bv, 2006) Demirbaş, AyhanThis article deals with slow pyrolysis of four shells such as hazelnut, walnut, almond and sunflower at the range of temperature 500-1200 K in a cylindrical reactor batch reactor. The aim of this work was to experimentally investigate how the temperature affects char, liquid and gaseous product yields from different shells via pyrolysis. The amount of char from pyrolysis of the shell samples decreases with increasing the pyrolysis temperature. The highest liquid yields were obtained from the samples between 650 and 800 K. The yield and the chemical composition of char can be calculated as functions of the pyrolysis temperature. The char components and higher heating values (HHVs) of shell fuels were correlated with pyrolysis temperatures. There were highly significant linear correlation between the pyrolysis temperature of the fuel and the fixed carbon content and HHV of char.Öğe Effects of Polymerization and Briquetting Parameters on the Tensile Strength of Briquettes Formed From Coal Coke and Aniline-Formaldehyde Resin(Taylor & Francis Inc, 2006) Demirbaş, Ayhan; Şimşek, TuncayIn this work, the utilization of aniline (C6H7N) formaldehyde (HCHO) resins as a binding agent of coke briquetting was investigated. Aniline (AN) formaldehyde (F) resins are a family of thermoplastics synthesized by condensing AN and F in an acid solution exhibiting high dielectric strength. The tensile strength sharply increases as the ratio of F to AN from 0.5 to 1.6, and it reaches the highest values between 1.6 and 2.2 F/AN ratio; it then slightly decreases. The highest tensile strength of F-AN resin-coke briquette (23.66 MN/m(2)) was obtained from the run with 1.5 of F/AN ratio by using (NH4)(2)S2O8 catalyst at 310 K briquetting temperature. The tensile strength of F-AN resin-coke briquette slightly decreased with increasing the catalyst percent to 0.10%, and then it sharply decreased to zero with increasing the catalyst percent to 0.2%. In general, the tensile strength of F-AN resin-coke briquette increased as increased the briquetting temperature in these tests contras with NaOH catalytic runs. The effect of pH on the tensile strength is irregular. As the pH of the mixture increases from 9.0 to 9.2, the tensile strength shows a sharp increase, and the curve reaches a plateau value between pH 9.3 and 9.9; then the tensile strength shows a slight increase after pH = 9.9.Öğe Electrical Power Production Facilities From Green Energy Sources(Taylor & Francis Inc, 2006) Demirbaş, AyhanGreen power refers to electricity supplied from more readily renewable energy sources than traditional electrical power sources. Green power products have become widespread in many electricity markets worldwide and can be derived from renewable energy sources. The environmental advantages of the production and use of green electricity by using green electricity seem to be clear. Using green energy sources like hydro, biomass, geothermal, and wind energy in electricity production reduces CO2, SO2, and NOx emissions. Market research indicates that there is a large potential market for green energy in Europe in general. Green power marketing has emerged in more than a dozen countries around the world.Öğe Electricity Generation Using Water Lifting Force(Multi Science Publ Co Ltd, 2006) Öztürk, Temel; Demirbaş, AyhanThis study has exhibited the advantage of electricity generation using water lifting force and explained how it is effectively used. Water is a renewable energy source which can be used in electricity generation by using its lifting force (buoyant force). It is important that an electricity generating apparatus using gravity and buoyancy can curtail costs of power generation and prevent environmental pollution and prevent destruction of an ecosystem. The hydraulic ram is an attractive solution for electricity generation where a large gravity flow exists. The wave conversion plant using buoyancy chambers is another solution for electricity generation using water lifting force. There are a good many reasons that water lifting force will be used in future at many ranges for electricity generation.Öğe Electricity Generation Via Unconventional Methods(Multi Science Publ Co Ltd, 2006) Demirbaş, AyhanConventional fossil energy will not be enough to meet the continuously increasing need for energy in the future. In this case, renewable energy sources will become important. Alternative energy sources are increasingly needed for energy in the future. Most electricity in the world is conventionally generated using coal, oil, natural gas, nuclear energy, or hydropower. Due to environmental concerns there is a growing interest in alternative energy sources for heat and electricity production. Some electricity production is done with alternative energy sources like biomass, geothermal, wind, and solar energy.Öğe An Investigation of Waste Foundry Sand in Asphalt Concrete Mixtures(Sage Publications Ltd, 2006) Bakış, Recep; Koyuncu, Hakan; Demirbaş, AyhanA laboratory study regarding the reuse of waste foundry sand in asphalt concrete production by replacing a certain portion of aggregate with WFS was undertaken. The results showed that replacement of 10% aggregates with waste foundry sand was found to be the most suitable for asphalt concrete mixtures. Furthermore, the chemical and physical properties of waste foundry sand were analysed in the laboratory to determine the potential effect on the environment. The results indicated that the investigated waste foundry sand did not significantly affect the environment around the deposition area.Öğe Potential evolution of Turkish agricultural residues as bio-gas, bio-char and bio-oil sources(PERGAMON-ELSEVIER SCIENCE LTD, 2006) Demirbaş, Ayhan; Pehlivan, Erol; Altun, TürkanA study has been conducted to evaluate the potential power production from the pyrolysis for bio-oil and bio-char, and anaerobic digestion (for bio-gas), of agricultural residues in Turkey. Agricultural residues are potential renewable energy resources such as bio-gas from anaerobic digestion, bio-oil from pyrolysis, and bio-char from carbonization and slow pyrolysis processes. Anaerobic bio-gas production is an effective process for conversion of a broad variety of agricultural biomass to methane to substitute natural gas and medium calorific value gases. When the pyrolysis temperature increased the bio-char yield decreased. The bio-char yield increased with increasing particle size of the sample. Thermochemical conversion processes of biomass are the most common and convenient methods for conversion into energy. Among the processes of energy production from biomass, pyrolysis is the most popular thermal conversion process. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.Öğe Turkey's natural gas, hydropower, and geothermal energy policies(TAYLOR & FRANCIS INC, 2004) Demirbaş, Ayhan; Demirbaş, Ayşe Şahin; Demirbaş, A. HilalThis article deals with Turkey's natural gas, hydropower, and geothermal energy policies. Turkey has made repeated efforts to increase foreign investment in its power industry. Turkey's energy demand is growing at 8% a year, one of the highest rates in the world. But investment has lagged far behind what is required to ensure reliable supply. Turkey's energy use causes serious air pollution problems. Furthermore, the government forecasts strong growth in fossil fuel use, including a four-fold increase in coal use by 2020 that would cause large greenhouse-gas emissions. While the forecasts may overestimate fossil fuel demand growth, the government must address the environmental issues rapidly. Specifically, Turkey needs a strategy that allows it to assume a concrete greenhouse gas emissions target no later than the second commitment period of the Kyoto Protocol. Natural gas consumption is the fastest growing primary energy source in Turkey. Turkey has supplied main natural gas needs from Russia; however Turkmen and Iranian gas represent economically sound alternatives. Hydroelectricity accounts for 45% of Turkey's total installed. Turkey continued, despite strong international criticism, to pursue its plans to construct the 1,200-megawatt Ilisu hydroelectric project. Ilisu is part of the Southeastern Anatolian Water Project, known as GAP. When completed, GAP will consist of 22 dams and 19 hydroelectric plants on the Euphrates and Tigris Rivers. Turkey has a total gross hydropower potential of 433 GW, but only 125 GW of the total hydroelectric potential of Turkey can be economically used. Turkey plans to increase hydropower production in the near future by especially using her small and micro hydroelectric plants (SHEPs and MHPs, respectively). Turkey is one of the geothermally potential rich 7 countries in the world. More than 1,000 hot and mineral water springs up to 373 K and 413 K geothermal fields with a temperature range of 313 to 505 K have been discovered in Turkey. Turkey has shot up the list of top direct use geothermal countries in recent years.
