Kullanılmış kızartma yağının alternatif dizel yakıtı olarak değerlendirilmesi

Abstract

Günümüzde kullanılan geleneksel enerji kaynakları rezervleri azalmakta ve özellikle bilinen petrol rezerv lerinin yakın bir gelecekte tükeneceği belirtilmektedir. Hızla artan nüfus ve endüstrileşme dünya enerji tüketi minde de artışa yal açmakta, bunun sonucu olarak ta enerji açısından yeni ve acil önlemlerin alınması zorun- luğu ortaya çıkmaktadır. Bilinen kaynakların en rasyo nel şekilde kullanımı ve yeni-yenilenebilir enerji kay naklarının değerlendirilmesi bu önlemlerin başlıcaları dır. Yeni yenilenebilir enerji kaynakları arasında bio kütlenin ayrı bir yeri ve önemi vardır. Ülkemizde petrol ürünleri tüketiminin büyük kısmı nı motor yakıtları oluşturmaktadır. Kara taşımacılığı ve tarımda yaygın olarak dizel motorlarının kullanılması, dizel yakıtının tüketimdeki payını arttırmaktadır. Ülke miz dizel yakıt üretiminin tüketimi karşılamaktan uzak olması., yeni yenilebilir kaynaklardan elde edilecek al ternatif dizel yakıtları özellikle önemli kılmaktadır. Yüksek ısıl değerleri ve uygun setan sayıları ile bitkisel yağlar, alternatif dizel yakıt olarak önemli bir potensiyeldirler. Bu konuda yapılacak çalışmalar Türkiye'nin tarımsal potansiyelinin değerlendirilmesi, yakıt tüketiminde dışa bağımlılığın azaltılması ve ülke mizi gelecekteki yeni enerji teknolojilerine hazırlaması açısından önemlidir. Bu amaçla yapılan çalışmamızda kullanılmış kızartma yağının alternatif dizel yakıt olarak kullanılabilirli ği araştırılmıştır. Çalışmanın ilk bölümünde kullanılmış kızartma yağının özellikleri ve yapısı belirlenmiş bulu nan değerler ayçiçek yağı ile karşılaştırılmıştır. Ça lışmanın ikinci kısmında ise, yağın yüksek viskozitesi, ASTM standart distilasyon cihazında gerçekleştirilen piroliz işlemi ile düşürülmeye çalışmıştır. Son bölümde ise elde edilen piroliz ürününün yakıt özellikleri belir lenmiş ve Petrol Ofisi Motorin Garanti f spesifikasyonu ile karşılaştırılmıştır. Ayrıca ürünün yapısı da belir lenmeye çalışılmıştır.

Energy consumption of the world tends to rise but resources deplete day by day. Today 85% of world's energy consumption is supplied by the fossil fuels of which crude oil constitutes the main part. The known petroleum sources will be exhausted in the near future. Because of this necessity man has to tend towards new and reneweable sources. As a developing country Turkey shares the same problems with others and energy is a matter of great importance for these countries. The use of biomasa as an alternative source of fuel is attracting interest in recent years. Vegetable oils are among th3 raw materials of biomass and they have a good potential as fuel for diesel engines. As Rudolph Diesel's first engine's fuel, vegetable oils show a good performance in short term engine tests. Some advantages of vegetable oils as fuel ara their portability, their availability, their heat content (90 % percent of diesel fuel), and their renewabilty. However in long term endurance tests a number of prob lems arise; first and the most important problem of vegetable oils as diesel fuel is their high viscosities which are nearly 10 times that of diesel fuel. High viscosity leads to poor atomization of the fuel, incomp lete combustion, coking on the fuel injectors, ring carbonization and accumulation of fuel in the lubricat ing oil which leads to thickening and gelation of lub ricating oil. Another problem is their nan volatility which causes inadequate fuel atomization and incomplete combustion. Unsaturated vegetable oils are highly reactive and tend to oxidize and polymerize. If such products accumulate in the lube oil, they could lead to thickening of the lubricating oil. VI Ta solve the viscosity problem mainly four methods are offered: dilution, microemulsif ication, transesteri- fication, and pyrolysis. Dilution: Vegetable oils are added to diesel fuel in known volume parts and viscoisty is tried to be decreased in this way. Microemulsions: Second approach ta reduce the viscosity is microemulsif ication with short chain al cohols, such as methanol or ethanol. Transesterif ication: Third approach to obtain loujEr viscosity is transesterif ication with simple alcohols to fatty eaters. Fatty eaters' low viscosity performed well in long term diesel engine testa. Pyrolysis: Last approach is pyrolysis, or cracking; this involves cleavage of chemical bonds to yield smaller molecules. There are two routes for pyrolysing the vegetable oils in literature. Some researchers use pyrex glass reactors for this reaction. Others pyroly- sed and distilled vegetable oils with standard ASTM distillation apparatus. Based on ideas which are cited above, in this study, used frying oil (UFO) was tried to be evaluated as diesel fuel. Used' frying oil from the kitchen of İstanbul Technical University Ayazağa Campus was identified and compared with commercial sunflower oil (CSO) in this study. Oil properties are given ip Tab le I. Second part of the study is pyrolysis. ASTM stan dard method for distillation öf petroleum products DS6- B2 was used for thermal decomposition of used frying oil. Figure I. shows distillation characteristics of used frying oil. These distillation curves do not rep resent just distillation but a combination of both distillation and cracking. Vll ,*. ıicori Fruina Oil and Commercial TABLE:- 1. Properties of Used trying Sunflower Dil Properties UFO CSD 20 Refractive Index, n*"£ Density, 20QC(g/cm3) Viscosity, 2aDC(mmz/s) Saponification Value Acid Value Unsaponified Matter(ut%) Monoglyaarida CrantentCuitft) Hydroxyl Value Per.Qxide Value Iodine Value(Hanus) TEMPERATURE ft) 488 T 0.9206 77 191.55 0.36 0.69 4. 57 14.8 VZk.k 1. »»W7 0.9214 69 205.56 0.20. 0-1.5 6.1B 19.2 26.32 136.11 SB 78 88 98 188 ->AH0UNT COLLECTED («D Figure-I.ASTM Distillation Curve of Used Frying Oil. Vlll BD% of the used frying ail distillate was collec ted between approximately 25D-35D C. Remaining part of the oil consists of nondistilled and noncondensed substances. The 1Q-ml fractions of distillates were stored at 2D C for 48 hours, and then dark colored semisolid waxy substances were filtered. Acid numbers and physical appearance of the collected fractions are given in table II. TABLE:II. Acid Values and Appearances Df Used Frying Dil Distillate Fractions. Fraction (ml) Apprearance Acid Value On the Dther hand 1D-ml fractions taken from the;.used frying oil distillate were tried to be analyzed for their hydrocarbon types by the ASTM standart method D 1319 but no satisfactory results could be obtained. Finally fuel properties of used frying oil crack ing and distillation product (DP) were determined and compared with the Petrol Dfisi Guaranty Specifications (G). Results are given in table. III. IX TABLE: III. Fuel Properties of Used Frying Oil Distillation and Pyrolysis Product. Properties Density, 15. 6DC (g/cm3) Viscosity, 37.8°C( mm2 /a) Flash point l°C) P.M.C.C Cloud Point (DC). Pour Point (DC) Ash (Weight %) Sulfur (Weight %) Water (Volume %) Ramsbottom Carbon Residue (Weight %) Corrosion, Copper Band, 3 h, 5GDC Higher Calorific Value ( MJ/kg ) * At 2QUC value produ subst cepta gave hand flash Used cosit oil a of di From this of used f ct is 89% itute used ble amount acceptable the amount point tern frying oil y is t 37 esel fuel. ca. t 37.8DC ( tabl ryin that fry of cop of para dis four 38 c e it c g oil of di ing oi sulfu per co carbon tures tillat times St), b an be s distill esel fu 1 disti r, ash, rrosion residu are not ion and lower ut it i een tha ation a el. As llation and ua value. e, clou within pyroly than th s still t high nd pyr a die produ ter co On t d, po accep sis pr at of highe er he olysi sel f ct ha ntent he ot ur, a table oduct used r tha ating s uel s ac- and her nd limits, 's vis- frying n that Althaugh these properties seem to limit the direct use of used frying ail distillation and paralysis pro duct as alternative diesel fuel far the time being, these unsuitable properties can be modified with the addition of proper additives. The pyrolysis product can also be used as a diluent to the diesel fuel and mixtures prepared in this may can be proposed as an alternative to diesel fuel itself depending an the results obtained from the engine tests.