Bitümlü şist ve plastiklerin kopirolizi

Özdemir, Mustafa
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Fen Bilimleri Enstitüsü
Son yıllarda petrol kaynaklan hızla azaldığı ve çevre kirliliğinin hızla arttığı araştırmacılar tarafından açıklanmıştır. Petrol eşdeğeri sentetik yakıtlara ve organik kimyasal maddelere kaynak teşkil edebilecek hammaddelere ihtiyaç vardır. Ekonomik bakımdan değeri düşük olan Göynük bitümlü şistlerinin ve kullanılmış plastiklerin beraber pirolizleri sonucu ele geçen ürünler ve bunların değerlendirilmesi üzerinde çalışılmıştır. Bu nedenle son senelerde tüm dünyada kullanılamayan bitümlü şistlerin ve senelerce doğada bozunmadan kalan plastiklerin tekrar kullanılması için çalışmalar yapılmıştır. Bitümlü şist ve plastikler ayrı ayrı ve farklı oranlarda karıştırılarak bunlara piroliz işlemi uygulanmış; elde edilen ürünlerin çeşitli yöntemlerle analizleri yapılmıştır. Ayrı ayrı elde edilen bütün piroliz ürünlerine pentan, toluen ve metanol eluentleri kullanılarak kolon kromatografisi uygulanmış ve bu elüentlerin içerdiği maddelerin analizleri gerçekleştirilmiştir.
Since the industrial revolution of the late 18th century, the overall standart of living in the developed world has increased greatly along with the energy requirements of a connstantly evolving society. The natural resources whic have been exploited to fulfil these energy requirements are finite and are being consumed at an ever increasing rate as the world population increases. Since 1973 however oil prices rose dramatically. The cost of a barrel of oil jumped from about US$ 2.40 in 1 973 to more than $30 in 1980. At present it seem to stable at about $ 25 per barrel but there is coherent instability which may trigger at any time thus future prices are unpredictable. The energy crises in the seventies revealed the increase in energy consumption, caused by the growth of the world's population, a rising standart of living and the economik growth. It became clear that the industrial countries depend too much on oil, which is not evenly distributed around the world. Furthermore, it was recognised that our fossil fuels are non-renewable energy resources and should be used accordingly this has led to aveneress for efficient for use of energy nowadays. Although renewable energy sources such as solar and wind energy, hydroelectric jenaration and biomass derived fuels, as well as alternative energy sources such as nuclear fission and fusion, have been investigated, due to environmental concerns and both technological and economic contrains, no suitable alternative non-fossil fuel energy source has been sufficiently developed to replace coal oil and gas as.the major energy source in the modern worid. Oil, although at present the most readily useable form of fossil fuel due to its ease of transport, storage and combustion, has the smallest natural reselves, estimated at less than 50 years based on current known reserves and consumption rates. The major oil reserves are located in the Middle East a region of political instability and as a consequence long term stable supplies of crued oil can not be guaranteed, as was demonstrated during the recent gulf crisis. All kinds of sediments involve varying amounts of organic matter. Although it is present in high consentrations in coal and peat deposits and accumulations of petroleum, natural gas and tar sands, much larger quantities occur as finely dispersed discrete organic particles in clastic sediments. Such sediments contaning high concentration of organic metter are refered to as oil shales. shreads of wood, bark and leaves, along with inorganic matter intimately mingled. The inorganic material consists mainly of clay with fine sand, calcite, dolamite and iron compounds. As the lakes dried out, the deposits became compacted and over geoligic time were transformed into inpermeable rocks. Oil shale comprise the second largest solid fuel reserve in Turkey, after lignites, reserves totalling approximately 5 million tones The largest reserve, Goynuk, is sitated near Bolu with an estimated 1 million tonnes in 100-150 m thick seams. The Seyitomer oil shale, located near Kütahya, contains 0.5 million tonnes with 20-40 m thick seams. Both oil shale deposits are found above lignite deposits. Currently, the Goynuk oil shale is stripped and stock piled to allow acces to the lignite while the Seyitomer oil shale blended with lignite as a power plant fuel. Oil from oil shale is often referred to as a "synthetic" fuel, but the organic matter in oil shale is a naturally occurring fossil fuel. In fact oil shale's organic matter is the world's largest supply of fossil fuel. There is no easy scientific definition of oil shale. According the Gavin "Oil shale is a compact, laminated rock of sedimentary origin, yielding over 33% of ash and containing organic matter that yields oil when distilled, but not appreciably when extracted with the ordinary solvents for petroleum". The term "oil shale" will be used to denote an organic-rich rock that contains little or no free oil. Source rocks are classified in terms of amount and type of organic matter. Two main approaches are used for characterizing the organic components in sedimentary rocks. Organic petrography used optical methods to identify and semiquantify the individual organic maturation. Organic geochemistry uses elemental and physico-chemical analyses to determine the composition and alteration of organic compounds and macerals in sediments. Shale oil is defined as the oil produced from an oil shale on heating. Three other terms will be used extensively, hence their definitions are important: Bitumen is defined as the organic material which can be extracted by common organic solvents such as benzene, toluene, tetrahydrofuran (THF) and chloroform or mixture of solvents, such as benzene, methanol. Kerogen, which comprise the major part of organic material, is not soluble in such solvents. Of course, these are operational definitions and the relative proportions of bitumen and kerogen depend on the choice of solvent and extraction conditions. The third term, kerogen concentrate, refers to the organic concentrate that is produced by benefaction or chemical demineralization of an oil shale. This term should refer only to that part of the organic concentrate that is insoluble in organic solvents. Modern society has been trying to solve the solid waste problem which is caused by urbanization, increasing consumption and environmental pollution. Vll Since the transportation of waste to long distance is not economical, several metods have been developed to dispose the solid waste. These methods include storage, biogas and compost production, recovering of recoverable parts of waste, pyroiysis and incineration. All these methods, depending on the waste composition and local conditions are being used in many countries. In countries where the topic is systematiclly approached, generally more than one methods are used for waste desposing. Incineration or burn out method has been used for centuries to burn the waste in the open areas. But in present times it is abondoned due to the environmental pollution considerations In order to bum the waste inclosed cell or fixed bed, one-or multi cell systems and try furnaces are developed. In addition mowing beds rotating furnaces, stoker and fluidised bed combustion are used. Since 1970's there has been increasing studies in order to developed the new techniques for thermal treatment of wastes. The studies started much earlier in the U.S.A, Japon, England and Denmark. Consequently numerous new waste processing system have been designed. Most of them are further developed. Of these methods, incineration is well known methods currently used. However it has some weaknesses such as; the large quantity of produced gas to be cleaned low burning efficency, sensitivity of the grade type systems to the waste constituents such as glass and plastics, need for additional energy and lack of possibilities of storing energy, loss of metals separated from ashes. In the pyroiysis basically the large organic molecules are cracked and converted into small molecules while a small portion becomes coke. The obtained liquid and solid organic products are fractioned and used as a raw material in industry. The gaseous products are used as fuel. The coke residue (obtained during the pyroiysis) may be used as fuel either by direct combustion or by gasification. The Göynük A oil shale from Turkey were collected from different locations in the excavated open-cast seams, crushed and reduced to 5 kg samples. The raw oil shales were crushed to 212 \im- 90 |im particle size. Than raw oil shale samples, plastic samples, mixture of oil shale and plastics have been pyrolysed in fix-bed retort. The prolysis of Göynük oil shales have been investigated under a range of conditions using a modified Heinze retort at Istanbul Technical University. The temperature was controlled using a thermocoupel inside the retort and the liquid traps were cooled by ice. The retort and liquid traps are made from stainlees stell. 250gr sample for oil shales, plastics and mixture were used in prolysis. In ail experimental runs, the retort was heated at 4 oc/ min to 700°C hold time of 60 min. The experiments were carried out in the self generated (static) atmosphere during pyroiysis. vui The raw shale oil (2 gr) is dissolved in n-pentane (100 cc) and pre- adsorbed on silicagel. After packing the glass column with activated silica and pre-adsorbed sample, the paraffins and to achieve a* clean separation between paraffins and aromatics; pentane to elute paraffins, toluene to elute aromatics and finally methanol to elute polars. Sample I Pentane I Filtration Insoluble Soluble Soluble Fraction Column Chromatography Pentane eluate Paraffins Toluene eluate Aromatics Methanol eluate Polar Compounds The pyrolysis and column chromatographic separation results are shown in Table 1. Aliphatic, aromatic and polar fractions were examined by GC-MS and FT/IR. Pentane fractions of Göynük shale oil, oil from polyethylene and oil from mixtures were mainly a mixture of saturated lineer alkanes and aikenes, besides a small percentage of alkadiens and branched homoiogs were observed. Aromatic fraction consisted of alkyl benzene and naphthylens. Polar fractions consisted of aromatic compounds with more than two condensed benzene rings and alkyl phenols. IX Table 1. Shale oil, polymer and copyrolysis values.
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 1995
Anahtar kelimeler
Bitümlü şistler, Plastikler, Oil shales, Plastics