Kolza sap-samanı piroliz katlı ürününün (Char) eldesi ve tanımlanması /
Yazar: AYDIN SEVER
Danışman: DOÇ. DR. FİLİZ KARAOSMANOĞLU
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Kimya Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 1998
Konu: Kimya Mühendisliği = Chemical Engineering
Dizin: Kolza = Rape ; Piroliz = Pyrolysis

Özet:
Türkiye, fosil enerji kaynak rezervleri çok sınırlı ve enerji tüketiminin büyük bölümünü dışalım ile karşılayan bir ülkedir. Mevcut enerji kaynaklarının verimli kullanımları yanısıra, yeni enerji teknolojileri kapsamında yeni kaynak seçeneklerinin de dikkate alınması yararlı olacaktır. Yeni enerji teknolojileri için en önemli kaynaklardan biri biyokütle olarak görülmekte; pek çok bitki ve artıkları doğrudan veya dönüşüm süreç ürünleri ile yakıt amaçlı değerlendirilebilmektedir. Süreç ürünlerinin bir bölümünün endüstriyel kimyasal olarak da değerlendirilmeleri de mümkündür. Biyokütlenin termokimyasal dönüşüm süreç katı ürünü (char); yakıt ve kimyasal olarak önemli bir konuma sahiptir. Bu çalışmada kolza sap-samanı chan eldesi ve charın tanımlanması amaçlanarak; kolza sap-samanının ısıl bozundurması gerçekleştirilerek, charın özellikleri saptanmış ve değerlendirilme seçenekleri ortaya konulmuştur.

Abstract:
The major alternatives to the conventional fossil fuels are renewable fuels. Renewables cover sources of energy such as solar, wind, hydro, geothermal, wave, tidal and biomass. The theoretical potential of biomass sources is large, since photosynthesis produce organic matter with an energy content of about 3xl0"2 J each year (1014 W year/year). This is about 10 times the present global commercial energy use and 200 times food energy consumption. Since the energy crisis of 1973, considerable interest has developed in the use of biomass to help meet the energy budget of the world. Biomass energy are destined to play an important role in the future energy systems of Turkey because of the great amount of energy imports from the other countries. Domestic coal, geothermal and hydro reserves of Turkey are approximately %1 of the world's total. However, oil and natural gas reserves of the country are very limited. In 1996, about % of the energy consumed was provided through imports. Turkey is facing several challenges such as increasing the energy production by using its natural resources, reducing the economical burden of energy imports, protect and improve the environment while enhancing the socio-economic development. Biomass, including wood, agricultural residues and animal wastes, has an important share in the primary energy production of Turkey. These fuels have been effectively used for heating and cooking purposes in the rural areas of the country. Turkey, whose energy production depends heavily on import fuels, has to explore the ways of increasing the use of biomass in energy production without destroying its valuable forest resources. One of the most promising options is the utilization of waste streams from forestry, agricultural residues are produced in Turkey and 60% of this total can be recovered for energy production. Agricultural residues, with an annual recoverable potential of 30-40 million dry tonnes and a primary energy equivalent of 525-700 PJ, are in important renewable source that can replace all the lignite and coal used in electric power generating plants in Turkey. This potential is expected to grow with the implementation of new irrigation projects. Turkey's geographic and climatic conditions are suitable for growing energy crops which are another sustainable option for Turkey to improve the environmental quality by providing and alternative to fossil fuels. Sorghum, switchgrass, short-rotation woody crops and hybrid poplar are among the high-productivity energy crops. Development and deployment of biofuels technologies in Turkey can alleviate many of the environmental concerns of conventional fuels. Although Turkey has the potential to initiate a domestic biofuels program, this issue still remains unaddressed in the state development plans. vinEnergy can be obtained from biomass through:. Direct combustion,. Physical process and. Conversion process. The simplest use of biomass is to burn it and the most common biomass used this way is wood, but corn stalks, dung and many other agricultural residues are also burnt on oppen fines for cooking, heating and other social purposes. Physical processes are grinding, drying, filtration, extraction and briquetting. If physical processes are employed to prepare biomass for conversion process, we called these as pretreatment processes. There are actually only two principal classes of conversion processes, thermal and biological. The major products of biological conversion processes are biogas hyrogen and ethanol. Thermal degradation processes (carbonisation, pyrolysis, gasification ) are most important in thermal conversion processes of biomass. Thermal degradation means thermal decomposition, without mentioning the gaseous environment in which the operation is performed: inert gas reducing gas or oxidizing gas. The modern definition is more accurate: thermal decomposition of organic matter, in vacuum or in an inert atmosphere (for example under pure nitrogen). With thermal degradation of biomass, the products are:. Liquid product (pyroligneous liquid, pyrolytic liquid): Pyroligneous liquids consists of pyroligneous acids or "wood spirit" soluble in water (composed of acids and alcohols) and tar (wood tar, tar, oil, pyrolytic oil) containing phenolics. Gas product (wood gas, pyrolytic gas) and. Solid product (char, charcoal). The relative proportions of these three main products depend on the chemical composition of the biomass used and on the operational conditions of thermal degradation process. Charcoal is very important product of thermal degradation processes. The wide range of charcoal properties results in many commercial applications, mainly in four different fields:. Domestic (cooking and heating),. Agricultural (tobacco processing),. Metallurgical (copper, bronze, steel, nickel, aluminium, and electro-manganese) and. Chemical (carbon disulphide, calcium carbide, silicon carbide, sodium cyanide, carbon monoxide, activated carbon, carbon black, fireworks, gaseous chemicals, absorbent, soil conditioner, and pharmaceuticals). Whether the charcoal can be regarded as as quality product, depends on its chemical and physical properties. As already seen, these are highly related to the raw material, properties of raw material, and the operating conditions of the thermal process. They will also determine the possibility of the char to undergo further treatment in order to provide more convenient final products such as char bricks and char pellets. Among IXthe properties which characterize charcoal, the more significant seen to be: yield, content of volatiles, fixed carbon condent, ash content, specific weight, hardness, heating value and active surface. Today's charcoal making process in developing countries, are characterized by low investment and maintenance costs, low labour costs, very limited recovery of by products, a restricted range of raw materials which may be carbonized, and generally a long process time. These types of reactor are similar to the more rudimentary stacked bed kilns. Along with the industrial development of the nineteenth century in developed countries, the potential value of the by-products suggested by the emergence of a new chemical industry and the increasing demand for charcoal of standard quality, encouraged the charcoal makers to modernize their installations. The improvements implemented to meet this neq situation qere essentially of three types.. The possibility for the new procedures to use a wide range of raw materials abundant in modern industrial life and very often unexploited, such as forestry and wood industry residues or agricultural and municipal wastes.. The appearance of continuously run retort decreasing sometimes dramatically the charcoal processing time.. Competitive equipment for the recovery of pyrolysis oil. More than one hundred charcoal processes are known today. In modern terminology, "kiln" is used for equipment producing only charcoal. "Retorts" and "Converters" are used for equipment capable of recovering by-products in commercial grade and quantity. Missouri kiln, Argentine kiln and Brazilian kilns are the examples of kiln. Lambiotte retort is an active usage in carbonization process. The Lambiotte continuous carbonization process is more suited for use in industrial countries than in developing countries in so for as it requires investment on an industrial countries than in developing countries in so for as it requires investment on an industrial scale, water and above all electricity. Converters (rotary kiln, fluidized bed, moving bed) are used for pyrolysing small size particles. Most of the new systems (Pillard rotary kiln, Gaylard process, CSIRO process etc) are designed to be able to pyrolyse small biomass particles to decrease investment and maintenance costs, and to increase the flexibility (various particle sizes, various grades of products). In this study characterisation of the char from the straw-stalk of rape plant researched and chars presented as biofuel and chemical. Materials in experimental study of stalk and straw of 00-kind rapeseed plant (Brassica napus L.) which were gathered from the field manually following the harvest during June 1995 in Thrace-Corlu-Turkey. Rapeseed straw and stalk were separated and cleaned from other florae and were stored on dry floor at room temperature in sacks. Rapeseed straw and stalk were ground in a Wiley mill during 1996 September to a grain size lower than 1 mm. The ground straw and stalk were stored in air tight plastic boxes and used up at experiments. The thermal degradation experiments were performed in static atmosphere andconducted in a 316 stainless steel tubular reactor. It has a 220 mm length and a diameter of 75 mm. Reactor is extermally heated by an electric furnace in which the temperature is measured by a thermocouple inside the reactor. The thermal degradation experiments performed final temperature of either 400, 500, 600, 700, 800, 900°C with 5 ±l°C/min heating rate. The liquid phase was collected in glass liners located in cold traps maintianed at -18°C and -40°C. The liquid phase consisted of aqueous and for phases. After thermal degradation the solid char was removed and weighed and also the weight of gas field was calculated by using its volume. Table 1 shows results of thermal degradation of straw-stalk of rape plant and Table 2 shows properties of the chars according to the standart methods. Table 1. Results of the thermal degradation experiments of straw-stalk of rape plant (on dry basis). As it can be seen from Table 1 liquid yields are higher than gas and char yields. Thermal degradation occured in the favour of pyrolysis. Char yield decreases with the increasing degradation temperature, whereas gaseous yield increases. This decrease and increase is significant until 700°C. Cellulose, hemicellulose and lignin in the structure of straw and stalk degrade almost until 700°C with exceeding this temperature some volatile matter was formed which in return resulted in an small increase of gas yield and a decrease of a char yield. An examination of liquid product yield indicates that there isn't a significant increase or decrease in yield and the that yield percentages are changing between %53-56. The properties of chars of straw and stalk of rapeseed can be seen in Table 2. The bulk densities and constitution of chars are changing depending on the temperature at which they obtained. The sulfur and nitrogen contents of chars are close to each other and not affected strongly from the changes of pyrolysis temperature. The carbon and ash contents of chars increase with the increasing pyrolysis temperature whereas hydrogen and oxygen contents decrease. The H/C and O/C molar ratios of chars decrease in pyrolysis temperature results in chars which are rich in carbon and have higher ash contents. The porosities of chars are affected by the change of the pyrolysis temperature. The only difference occurs at 900°C where at this temperature obtained chars have pore diameters that are smaller and that they surface areas are greater than the other ones. Chars have significiantly lower surface areas. In order ta see the effect of heating rate on the char properties two different rates namely 1 0 -F 1 °C/min and 1 5 -F 1 °C/min were conducted at 800°C for pyrolysis experiments. It is determined that the u o o o ON o m n în ~ g^ vo oo On «o m m j o o o © -©-S Ö ^ °. m (N ^ O r» o m o S es o -; ^fr U S O o O O oo o r- t 00 li-l £ ON o JsSS2 ON O vo m »n O o O O r- o o od o *2O0\rtifl^00m ~ es es m m H - ı © 8 vo ö VO 2 es w-> - < oo O Tt" »o VO «O CS S «1 ^ cK O <-> - ı o. ö u o O O VO O VO ON lO VO -st 00 ?*fr" >-< m' t-. «-* i- ı oo oo ->tf- es m oo On ro »O O en 2©o °. ri r-«. es r~- § ^ M VO İT) ı- es es, es O ^ *- U O o O O O °o o en en ON oo.st- m es.* es es VO -l N«2°H'20'°' - es ö m OK Î8 rs oo es vo t-»- ?<*. m vo ^ ~ es es o vd o <- ~ I o 8.fi es.S u O ffi O ot ; xııchange of heating rate didn't affected strongly the product properties and yields. In contrary the pore properties are affected by the increase of the heating rate. Investigations are conducted through FTIR and SEM and similar structure are observed.