• Energy Research
• Closed Access close
• Restricted close
• Open Source close
• Embargo close
• Turkish close

ÖZET Günümüzde, linyit kömürlerinde, özellikle üretim ve depolama aşamasında rastlanan kayıpları oldukça yüksek rakamlara çıkaran en önemli problemlerden biri de şüphesiz linyit kömürlerinin kendiliğinden yanması veya diğer tabiri ile oksitlenmesidir. Bu çalışma, düşük sıcaklıkta, linyitlerde oksitlenmenin nedenlerini araştırarak gerekli tedbirleri almak yanma olayını önceden engelleyecek sağlıklı çözümler üretmek üzerinedir. Bu çalışmada, Soma havzasından 3 çeşit linyit numunesi (Eynez, Deniş- yıkanmış, Deniş-tuvenan) kullanılmıştır. Numuneler çeşitli numune azaltma yöntemleri ile 1 kg' a indirilmiş, sonra da taboratuvar çaplı kinci ve değirmenler yardımı ile tane iriliği -60 mikrona getirilerek deneye hazırlanmıştır. Bu numuneler, TGA (Thermo Gravimetric Analysis) cihazında 400 °C'ye kadar dakikada 2, 3 ve 5 °C 'lik sıcaklık artışlarında, oksijen konsantrasyonu düşük ve yüksek olarak ayarlanmış ortamlarda işleme tabi tutulmuştur. Elde edilen değerler, grafik olarak bilgisayardan alınmış ve numunelerin kütle değişimleri, grafikler yardımı ile analiz edilmiştir. ABSTRACT In these days, one of the most important problems that raise the losses in lignite coal during production and storage to high levels, is that it self-burns or in other words gets oxidized. This study is concerned with researching the causes of oxidization at low temperatures, take the necessary measure and produce healty solutions in order to prevent burning in advance. In this study, three kinds of lignite samples from Soma (Eynez, Denis-washed P$MDeniş-run ofrnine) have been used. Samples have been reduced down to 1 kg. by means of vjripus sample reduction methods and later prepared for experiments having crushed ajid ground to a particle size of -60 micron with the help of crushers and mills at laboratory scale. These samples have been treated in either low 02 concentration or high concentration medium with temperature rises of 2,3 and 5 oC /min. up to 400 oC in TGA. The values have been derived from the computer in the form of graphs and the moss changes of the samples have been analysed graphically. 71

ÖZET Günümüzde, linyit kömürlerinde, özellikle üretim ve depolama aşamasında rastlanan kayıpları oldukça yüksek rakamlara çıkaran en önemli problemlerden biri de şüphesiz linyit kömürlerinin kendiliğinden yanması veya diğer tabiri ile oksitlenmesidir. Bu çalışma, düşük sıcaklıkta, linyitlerde oksitlenmenin nedenlerini araştırarak gerekli tedbirleri almak yanma olayını önceden engelleyecek sağlıklı çözümler üretmek üzerinedir. Bu çalışmada, Soma havzasından 3 çeşit linyit numunesi (Eynez, Deniş- yıkanmış, Deniş-tuvenan) kullanılmıştır. Numuneler çeşitli numune azaltma yöntemleri ile 1 kg' a indirilmiş, sonra da taboratuvar çaplı kinci ve değirmenler yardımı ile tane iriliği -60 mikrona getirilerek deneye hazırlanmıştır. Bu numuneler, TGA (Thermo Gravimetric Analysis) cihazında 400 °C'ye kadar dakikada 2, 3 ve 5 °C 'lik sıcaklık artışlarında, oksijen konsantrasyonu düşük ve yüksek olarak ayarlanmış ortamlarda işleme tabi tutulmuştur. Elde edilen değerler, grafik olarak bilgisayardan alınmış ve numunelerin kütle değişimleri, grafikler yardımı ile analiz edilmiştir. ABSTRACT In these days, one of the most important problems that raise the losses in lignite coal during production and storage to high levels, is that it self-burns or in other words gets oxidized. This study is concerned with researching the causes of oxidization at low temperatures, take the necessary measure and produce healty solutions in order to prevent burning in advance. In this study, three kinds of lignite samples from Soma (Eynez, Denis-washed P$MDeniş-run ofrnine) have been used. Samples have been reduced down to 1 kg. by means of vjripus sample reduction methods and later prepared for experiments having crushed ajid ground to a particle size of -60 micron with the help of crushers and mills at laboratory scale. These samples have been treated in either low 02 concentration or high concentration medium with temperature rises of 2,3 and 5 oC /min. up to 400 oC in TGA. The values have been derived from the computer in the form of graphs and the moss changes of the samples have been analysed graphically. 71

In the recent years, rapid increase in theoretical studies and applications on electrical power generation from renewable sources, such as wind, sun, marine or tidal currents, can be encountered in the literature. Among these, marine current turbines, produce energy by taking the advantage of alternating motion of water, and have the ability to produce energy even at low flow rates, and are operated in oceans and seas as a renewable energy source. In this study, design of marine current turbine, to be installed on a zero emission sail boat consept as a prominent renewable energy source, is done. Firstly, the design requirements of marine current turbine to be installed on the sailboat are determined. So forth, prerequisites for two marine current turbines, at starboard and port, are turbine diameters to be less than 700 mm, design speed to be 3.1 m / s (6 knots), electrical power generation to be not less than 850 W, total appendage resistance to be not exceeding 5% of the ship resistance during the motor cruising and also 25% of the ship resistance during the sailing, in total, and weight of each turbine to be not exceeding 35 kg. Considering the prerequisites above, low Reynolds number turbine blade section profile FX63-167, also used wind turbine blade section with the highest CL/CD (lift coefficient/drag coefficient) ratio, is chosen. Nevertheless, considering manufacturing and productivity, changes in the geometry of trailing edge of the section is done. TSR, a substantial parameter for marine turbines, and turbine diameter data from available five marine current turbine in production, ranging in diameter 3.1-6.3 m are taken into account. For design, TSR and turbine diameter (D) are considered to be 3.4 and 0.5 m, respectively. TSR is an important parameter in turbine design. Turbine, under the boat, aims to convert energy to water flow that occurs on its body during the course of sailing. In the meanwhile, it is causes an additional resistance by acting as an appendage on sail boat. The additional appendage resistance reduces the speed of boat. It is inevitable. To overcome, the most efficient system can be developed by reducing it to the minimum. The additional appendage resistance on the sail boat occurs, since the two kinds of hydrodynamic forces are generated on turbine. The first hydrodynamic force is the viscous resistance component caused by flow around turbine geometry. The other hydrodynamic force is opposed thrust force, rotational thrust acting in the opposite direction of boat motion, occurring on turbine blades and trying to stop the boat. The opposed thrust increases in proportion with the increase in rotational speed of the turbine. Therefore, choosing lower TSR values is concluded in this study. A computer code, based on momentum blade element method, is used for blade geometry design and optimization. At the end of optimization, turbine speed (N), power coefficient (CP), tip speed ratio (TSR), torque (T), thrust (F) and theoretical power are calculated to be 460 rpm, 0.461, 3.882, 8.72 Nm, 827 N, 1383.5 W, respectively. The calculated final geometric values for the turbine blades are given. For the results obtained in pre-design calculations to be close to practice and actual, turbine mechanical design, including hub and pod parts, is also carried out. The reason for the system to be preferred as a folding system, is to minimize the flow-induced resistances during the motor cruising. A horizontal axis marine current turbine system with all components is designed and presented. As a result, an efficient, durable, easy to operate, and innovative product is presented for sailing boat which has capability to generate, accumulate and consume alternative energy by using solar and/or wind renewable energy sources. Son yıllarda, rüzgar ve güneş enerjisi ile deniz ve gel-git akıntıları gibi yenilenebilir kaynaklardan elektrik enerjisi üretimi üzerine yapılan teorik çalışmaların ve uygulamaların hızlı bir şekilde arttığı görülmektedir. Bunlardan sualtı akıntı türbinleri, suyun değişik hareketlerinden yararlanarak enerji üreten sistemler arasında olan ve düşük akım hızlarında dahi enerji üretebilme yeteneğine sahip, okyanus ve denizlerde işletilen enerji üretme yöntemlerinden biridir. Bu çalışmada, yelkenli bir tekne üzerinde sabit bulunacak ve yelken seyri sırasında tekne gövdesi etrafındaki akıştan enerji elde edecek bir su altı akıntı türbininin, fonksiyon gereksinimleri doğrultusunda ön tasarımı ve detay tasarımı gerçekleştirilmiştir. Tasarım aşamalarında, su altı türbin kanatlarının dizaynı, analizi ve optimizasyonunda yaygın olarak kullanılan momentum kanat elemanı yöntemi (MBEM)’nden yararlanılmıştır. Ön tasarım ve detay tasarım sonucunda ortaya çıkan yatay eksenli sualtı türbin sistemi, bileşenleri ile birlikte gösterilmiştir. Bu sayede, üzerinde rüzgâr ve/veya güneş gibi yenilenebilir enerji kaynaklarından enerji elde edebilen, depolayabilen ve gerektiğinde bu enerjiyi kullanabilen donanıma sahip her yelkenli tekne için, güneş ve rüzgâr teknolojilerine göre daha fazla güç üretebilen, verimli, uzun ömürlü, kullanımı kolay ve yenilikçi bir ürün ortaya konmuştur.

In the recent years, rapid increase in theoretical studies and applications on electrical power generation from renewable sources, such as wind, sun, marine or tidal currents, can be encountered in the literature. Among these, marine current turbines, produce energy by taking the advantage of alternating motion of water, and have the ability to produce energy even at low flow rates, and are operated in oceans and seas as a renewable energy source. In this study, design of marine current turbine, to be installed on a zero emission sail boat consept as a prominent renewable energy source, is done. Firstly, the design requirements of marine current turbine to be installed on the sailboat are determined. So forth, prerequisites for two marine current turbines, at starboard and port, are turbine diameters to be less than 700 mm, design speed to be 3.1 m / s (6 knots), electrical power generation to be not less than 850 W, total appendage resistance to be not exceeding 5% of the ship resistance during the motor cruising and also 25% of the ship resistance during the sailing, in total, and weight of each turbine to be not exceeding 35 kg. Considering the prerequisites above, low Reynolds number turbine blade section profile FX63-167, also used wind turbine blade section with the highest CL/CD (lift coefficient/drag coefficient) ratio, is chosen. Nevertheless, considering manufacturing and productivity, changes in the geometry of trailing edge of the section is done. TSR, a substantial parameter for marine turbines, and turbine diameter data from available five marine current turbine in production, ranging in diameter 3.1-6.3 m are taken into account. For design, TSR and turbine diameter (D) are considered to be 3.4 and 0.5 m, respectively. TSR is an important parameter in turbine design. Turbine, under the boat, aims to convert energy to water flow that occurs on its body during the course of sailing. In the meanwhile, it is causes an additional resistance by acting as an appendage on sail boat. The additional appendage resistance reduces the speed of boat. It is inevitable. To overcome, the most efficient system can be developed by reducing it to the minimum. The additional appendage resistance on the sail boat occurs, since the two kinds of hydrodynamic forces are generated on turbine. The first hydrodynamic force is the viscous resistance component caused by flow around turbine geometry. The other hydrodynamic force is opposed thrust force, rotational thrust acting in the opposite direction of boat motion, occurring on turbine blades and trying to stop the boat. The opposed thrust increases in proportion with the increase in rotational speed of the turbine. Therefore, choosing lower TSR values is concluded in this study. A computer code, based on momentum blade element method, is used for blade geometry design and optimization. At the end of optimization, turbine speed (N), power coefficient (CP), tip speed ratio (TSR), torque (T), thrust (F) and theoretical power are calculated to be 460 rpm, 0.461, 3.882, 8.72 Nm, 827 N, 1383.5 W, respectively. The calculated final geometric values for the turbine blades are given. For the results obtained in pre-design calculations to be close to practice and actual, turbine mechanical design, including hub and pod parts, is also carried out. The reason for the system to be preferred as a folding system, is to minimize the flow-induced resistances during the motor cruising. A horizontal axis marine current turbine system with all components is designed and presented. As a result, an efficient, durable, easy to operate, and innovative product is presented for sailing boat which has capability to generate, accumulate and consume alternative energy by using solar and/or wind renewable energy sources. Son yıllarda, rüzgar ve güneş enerjisi ile deniz ve gel-git akıntıları gibi yenilenebilir kaynaklardan elektrik enerjisi üretimi üzerine yapılan teorik çalışmaların ve uygulamaların hızlı bir şekilde arttığı görülmektedir. Bunlardan sualtı akıntı türbinleri, suyun değişik hareketlerinden yararlanarak enerji üreten sistemler arasında olan ve düşük akım hızlarında dahi enerji üretebilme yeteneğine sahip, okyanus ve denizlerde işletilen enerji üretme yöntemlerinden biridir. Bu çalışmada, yelkenli bir tekne üzerinde sabit bulunacak ve yelken seyri sırasında tekne gövdesi etrafındaki akıştan enerji elde edecek bir su altı akıntı türbininin, fonksiyon gereksinimleri doğrultusunda ön tasarımı ve detay tasarımı gerçekleştirilmiştir. Tasarım aşamalarında, su altı türbin kanatlarının dizaynı, analizi ve optimizasyonunda yaygın olarak kullanılan momentum kanat elemanı yöntemi (MBEM)’nden yararlanılmıştır. Ön tasarım ve detay tasarım sonucunda ortaya çıkan yatay eksenli sualtı türbin sistemi, bileşenleri ile birlikte gösterilmiştir. Bu sayede, üzerinde rüzgâr ve/veya güneş gibi yenilenebilir enerji kaynaklarından enerji elde edebilen, depolayabilen ve gerektiğinde bu enerjiyi kullanabilen donanıma sahip her yelkenli tekne için, güneş ve rüzgâr teknolojilerine göre daha fazla güç üretebilen, verimli, uzun ömürlü, kullanımı kolay ve yenilikçi bir ürün ortaya konmuştur.

ABSTRAKT Bu çalışma, sera domates yetiştiriciliğinde, güneş enerjisinden maksimum düzeyde yararlanabilmek, seralardan geceleri meydana gelen ısı kayıplarını azaltmak, bitki çevresindeki ve kök bölgesindeki sıcaklığı arttırmak amacıyla 1987-1989 yılları arasında yürütülmüştür. Cam ve camjel ile kontrol edilen (gündüz açılıp gece kapanan)PE ısı perdesi tek ürün yetiştiriciliğinde denenmiş ve her ikisinde de (a) kontrol, (b) siyah PE malç,(c) şeffaf PE malç,(d). siyah PE malç -J- alçak plastik tünel, (e) şeffaf PE malç 4 alçak plastik tünel ve (f) alçak plastik tünel olmak üzere B uygulama yer almıştır. Farklı plastik malç ve malç 4 alçak plastik tünel uygulamaları ilkbahar ve sonbahar yetiştirme dönemlerinde de 2 ayrı deneme halinde yürütülmüştür. Sera içi ve tünel altı sıcaklık ve nem değerleri, 10 cm. derinlikteki toprak sıcaklıkları her yetiştirme döneminde ve herbir uygulama için saptanmış ve bunların vegetatif ve generatif gelişme, verim ve meyve kalitesi üzerindeki etkileri araştırılmıştır. ABSTRACT Thia study aiming ta get the maximum benefit from solar energy, to decrease the heat loss within the glasshouse at night and to increase the temperatures of both the root region and the surrounding of the plant in glasshouse tomato production was carried out between 1987 and 1589. In long season crop production, glass and glass polyethylene (PE) thermal screen that could be controlled manually and could be opened during the day and closed at night were compared. In both cases 6 different applications were tested (a) control, (b)tolack PE mulch, (c) transparent PE mulch, (d) black PE mulch 4 low plastik tunnel, (e) transparent PE mulch 4 1°^ plastic tunnel and (f) low plastic tunnel. These mentioned ; plastic mulches and mulch 4 lQw plastic tunnel combinations were compared in two separate trials as spring and autumn crop production. The temperatures and relative humidities within the glasshouse and tunnels and the soil temperatures at a depth of 10 cm. were recor ded for every growing period and for every variant. Their effects on vegetative and generative growth, yield and fruit quality were also determined. 117

ABSTRAKT Bu çalışma, sera domates yetiştiriciliğinde, güneş enerjisinden maksimum düzeyde yararlanabilmek, seralardan geceleri meydana gelen ısı kayıplarını azaltmak, bitki çevresindeki ve kök bölgesindeki sıcaklığı arttırmak amacıyla 1987-1989 yılları arasında yürütülmüştür. Cam ve camjel ile kontrol edilen (gündüz açılıp gece kapanan)PE ısı perdesi tek ürün yetiştiriciliğinde denenmiş ve her ikisinde de (a) kontrol, (b) siyah PE malç,(c) şeffaf PE malç,(d). siyah PE malç -J- alçak plastik tünel, (e) şeffaf PE malç 4 alçak plastik tünel ve (f) alçak plastik tünel olmak üzere B uygulama yer almıştır. Farklı plastik malç ve malç 4 alçak plastik tünel uygulamaları ilkbahar ve sonbahar yetiştirme dönemlerinde de 2 ayrı deneme halinde yürütülmüştür. Sera içi ve tünel altı sıcaklık ve nem değerleri, 10 cm. derinlikteki toprak sıcaklıkları her yetiştirme döneminde ve herbir uygulama için saptanmış ve bunların vegetatif ve generatif gelişme, verim ve meyve kalitesi üzerindeki etkileri araştırılmıştır. ABSTRACT Thia study aiming ta get the maximum benefit from solar energy, to decrease the heat loss within the glasshouse at night and to increase the temperatures of both the root region and the surrounding of the plant in glasshouse tomato production was carried out between 1987 and 1589. In long season crop production, glass and glass polyethylene (PE) thermal screen that could be controlled manually and could be opened during the day and closed at night were compared. In both cases 6 different applications were tested (a) control, (b)tolack PE mulch, (c) transparent PE mulch, (d) black PE mulch 4 low plastik tunnel, (e) transparent PE mulch 4 1°^ plastic tunnel and (f) low plastic tunnel. These mentioned ; plastic mulches and mulch 4 lQw plastic tunnel combinations were compared in two separate trials as spring and autumn crop production. The temperatures and relative humidities within the glasshouse and tunnels and the soil temperatures at a depth of 10 cm. were recor ded for every growing period and for every variant. Their effects on vegetative and generative growth, yield and fruit quality were also determined. 117

THE EFFECT OF ADDITIVES ON THE FUSION TEMPERATURES OF COALS SUMMARY In coal processing, coal ash may cause serious problems such as clinker trouble in fluidized bed gasifiers, sintering in stoker combustors, agglomeration in fluidized bed combustors, fouling of heating surface in combustors, vaporization of harmful elements from the ash. Therefore, prediction of ash behavior is of vital importance, particularly for combustion systems In fluidized bed combustion systems, agglomeration (sintering) of ash (coal) and bed material particles can cause severe problems. As a result of agglomeration, deposition can form on heat transfer surfaces and bed walls. Accumulation of sticky ashes on surfaces can cause substantial decrease in heat transfer coefficient, disturb air distribution and consequently fluidization in the bed. In the most serious cases, sintering of particles can lead to heavy agglomerate mass which finally disturb fluidization and combustion completely. In these cases the system has to be dismantled in order to remove agglomerates and restore the normal operation. The measurement of so called characteristic ash temperatures, namely initial deformation temperature (IT), softening temperature (ST), hemispherical temperature (HT) and fusion temperature (FT) is considered to be one of the best methods to estimate the behavior of coal ash in coal combustors in practice. The agglomeration is a process which describes formation of agglomerates from particles under heating. The earlier works suggest that, in fluidized bed combustors, agglomeration can occur as a result of partial melting and stickiness of bed particles due to the operating of fluidized bed at temperatures higher than the melting point of coal. But later research indicate that agglomeration can occur at temperatures much lower than the ash fusion temperature. The temperature at which agglomeration starts is called first sintering temperature. The properties and behavior of ashes are remarkably different among coals and since coal ash is extremely complex mixture of minerals it is not possible to predict the fusion behavior of such mixture from its chemical composition with a reasonable accuracy. Many correlations have been developed to estimate the softening and fusion behavior of ashes from their chemical composition, in general, all of them suggest that the softening and fusion temperatutes increase as the amounts of asidic oxides (SİO2, AI2O3) in the ash increase. Therefore, it is essential to study the individual coal deposit in order to see how they exactly behave in practical combustion. The objectives of this work is to determine the characteristic ash temperatures of some major Turkish lignites, to investigate the relationship between their temperatures and inorganic compositions and relationship between ash fusiontemperatures and inorganic compositions and relationship between ash fusion temperature and agglomeration temperature of some selected coals. The effect of addition of some metal oxides which are the major component of ashes of coals on the characteristic temperatures is also investigated. Ten coal samples studied were taken from the major lignite deposits in various districts of Turkey. One sample out of ten is oil shale. The samples are ; 1 ) Beypazarı - Ankara 2 ) Çan - Çanakkale 3 ) Elmalı ( Soma ) - Manisa 4 ) Eynez - Manisa 5 ) Deniş ( Soma ) - Manisa 6 ) Göynük - Bolu 7 ) Göynük Oil shale - Bolu 8 ) Kısrakdere - Manisa 9 ) Tunçbilek - Kütahya 10) Yatağan - Muğla The following analyses were carried out in order to characterize coal samples and ashes : Proximate analysis, elemental analysis, measurement of characteristic temperatures and chemical analysis of ashes. Coal samples were crushed and sieved to - 200 mesh and ashes were prepared using the TS 330 procedures. Ash compositions were determined according to ASTM procedure D 2795 - 86. Ash fusion measurements were made by using a LECO AF - 500 type ash fusion furnace with digital read - out, sensivity of 5K and a maximum temperature of 1844 K according to the ASTM procedure D 1857 - 68. Ash cones were prepared and put into the furnace and were heated to the fusion temperature with a heating rate of 8 K/ min. under oxidizing gas atmosphere. The results are presented as the an average values of repeated measurements. The results of chemical analysis of ashes and ash fusion measurements are presented in Table 1 and Table 2 respectively. As seen from Table 2, initial deformation temperatures and fusion temperatures of lignites change between 1377 - 1573 K and 1482 - 1844 K, respectively. The fusion temperature of Eynez lignite was out of the temperature range of ash fusion furnace and it could not be measured exactly. Comparison of Table 1 and Table 2 indicated that, in general, coals with higher Si02 and lower Fe203 contents such as Eynez, Elmalı, Kısrakdere, Tunçbilek and Yatağan lignites have higher initial deformation and fusion temperatures while coals with higher Na20 percentages have lower fusion temperatures. However, no regular relationship is seen between chemical composition and critical temperatures of ashes. For example, in spite of their high Na20 percentages, Eynez, Kısrakdere and Tunçbilek lignites have fusion temperatures higher than that those with lower Na20 percentages. In Figure 1, the initial deformation temperatures are given as a function of total percentage of (Na20 + K20 + CaO + MgO). These oxides are called basic oxides which are considered, chemically, to be the most active components and have the leading role in agglomeration (sintering) behavior of ash. It is clear from figure that no regular relationship between composition and deformation temperature can bedescibed for original coal ashes. The initial deformation temperature differs widely even for ashes having nearly the same total basic oxide percentage. A set of experiments was carried out by using of Na2C03, K2CO3, CaO and MgO as additives to ashes in order to investigate the relationship between the X U.m&<*J..lIX-/.CA,I1^-TVJX^VS^IT : Initial deformation temperature, ST : Softening temperature, HT temperature, FT :Fusion temperature. Hemispherical composition and fusion charteristics for the individual ashes. In these experiments, CaO and Na20 contents of all ashes were increased by adding of CaO and Na2C03. K2C03 and MgO were added only to Beypazarı lignite ash. The characteristic temperatures of Beypazarı Elmah, Eynez, Tunçbilek and Yatağan lignites and Göynük oil shale decreased regularly with increasing CaO content while no considerable changes was observed for other lignites. A maximum decrease of 130 K was determined in fusion temperature with an increase of 9% in CaO for Eynez and Yatağan lignites. The Na20 content of ashes was increasd by using Na2CÛ3. Increasing of the amount of Na20 lowered the characteristic temperatures of Beypazarı, Çan, Eynez, Kısrakdere, Tunçbilek and Yatağan lignite ashes. Temperature profiles of Elmah XIlignite ash had a minimun around 8% Na20 below which temperatures decreased while above which increased slightly with increase in Na20 contest. Increasing of Na20 content by 10%, caused a 120 K and 180 K reduction in fusion temperatures of Beypazarı and Eynez lignite, respectively, which were the highest reductions determined. Other ashes were not affected significantly by the Na20. 10 15 20 25 30 %{CaO+ MgO+ Na20+ K20} 35 40 Figure 1. Change of fusion temperature of oginal coal ashes with (Na20 + K20 + CaO + MgO) % Another topic studied in this work is the relationship between the agglomeration and characteristic temperatures of lignites. For this purpose, a set of experiments was performed in which the agglomeration temperatures (Tag) of Beypazarı, Çan, Eynez, Kisrakdere, Göynük and Yatağan lignites were determined in a 10 cm id fluidized bed combustor. Results of agglomeration measurements are compiled in Table 3. The difference between agglomeration temperature and characteristic temperatures are also included in the Table. The differences described as AT, = IT - Tag, AT2 = ST - TAG, AT3= HT - TAG, AT4 = FT - TAG Agglomeration tempertures listed in Table 3 are lowest temperatures where first agglomerates formed. Data in the table indicate that agglomeration of lignite can occur at temperatures several hundred degrees below fusion temperature for a lignite in a fluidized bed coal combustor. Values of ATi, AT2, AT3 > AT4 show that the agglomeration behavior of lignites with different ash compositions vary widely and can not be explained on the basis of ash fusion temperature. XIITable 3. Agglomeration Temperature of Some Lignites. X1U ÖZET Kömür yakma sistemlerinde karşılaşılan sinterlesme ve aglomerasyon olayları, yanmanın sürekliliği açısından problem yaratmakta ve sistemin verimim olumsuz yönde etkilemektedir. Aglomerasyon, kül taneciklerinin birbirine yapışıp, katı bir kütle haline gelmesi olayıdır ve özellikle akışkan yataklı yakma sistemlerinde karşılaşılan önemli bir. problemdir. Temel olarak kömürün anorganik yapı özelliklerinden kaynaklanmaktadır. Bu nedenle JmL ergime sıcakhldarı ve aglomerasyon özellikleri arasında bir etkileşim olduğu sarınmaktadır. Bu çalışmada, 9 linyit ile bir bitümlü şistin küllerinin anorganik yapılan ile özgül sıcaklıkları olarak bilinen, başlangıç deformasyon (İT), yumuşama (ST), yan küreselleşme (HT) ve akma {FT) sıcaklıkları arasındaki ilişki incelenmiştir. Çalışmada, hem orjinal, hem de belirli oranlarda, Na2C03, K2C03, CaO ve MgO katılarak bileşimleri değiştirilmiş olan `katkılı küller` göz önüne alınmıştır. Küllerin anorganik yapılan, standart yöntemler kullanılarak belirlenmiştir. Özgül sıcaklıkları LECO AF 500 model bir cihaz kullanılarak, ASTM D 1857 ' ye göre oksitleyici atmosferde ölçülmüştür. Aglomerasyon sıcaklıkları ise 10 cm çapında bir akışkan yatakta ölçülmüştür. Orjinal küllerin İT değerleri 1377-1576 K, ST değerleri 1414-1801 K, HT değerleri 1460-1814 K, FT değerleri 1482- 1844 K arasında değişmektedir. Özgül sıcaklıkları en yüksek olan kömü Eynez linyiti, en düşük olan ise Göynük bitümlü şisti olmuştur. Orjinal küllerin anorganik yapılan ile özgül sıcaklıklan arasında sistematik herhangibir ilişki görülmemiştir. Genel olarak, Na20 içerikleri yüksek olan kömürlerin çoğunlukla daha düşük sıcaklıklarda, buna karşın SİO2 oranlan yüksek ve Fe203 oranlan düşük kömürler ise daha yüksek sıcaklıklarda ergimiştir. Ancak bu durum incelene bütün kömürler için, geçerli değildir. Aynı tür küllerin yapısal değişimlerini özgül sıcaklıklara etkisini görmek amacıyla, bazı küllere değişik oranlarda Na2C03, K2CO3, CaO ve MgO katılarak hazırlanan katkılı küllerle yapılan ölçümlerin sonuçlan, sıcaklıklan en fazla etkileyen katkının Na2C030İduğunu göstermiştir. Toplam Na20 içeriğine bağlı olarak, özgül sıcaklıklarda genelde bir düşme eğilimi gözlenmiştir. Na20 katkısı bazı kömürlerin ergime sıcaklıklarını 120 K kada^düşürmüştür. Kömürlerin aglomerasyon sıcaklıkları, deformasyon sıcaklıklarına (IT) allında kalmaktadır. Aglomerasyon sıcaklıkları İT değerlerinden 175-346 K, ergime sıcaklıklarından ise, yaklaşık olarak 346-551 K daha düşük olmuştur. Akışkan yataklarda yanan kömür taneciklerinin sıcaklığının ölçülen ortalama yatak sıcaklığından yaklaşık olarak, 100-150 K daha yüksek olduğu göz önüne alındığında, aglomerasyonun deformasyon sıcaklığında veya ona çok yalan sıcaklık seviyelerinde başladığı anlaşılmaktadır. 79

THE EFFECT OF ADDITIVES ON THE FUSION TEMPERATURES OF COALS SUMMARY In coal processing, coal ash may cause serious problems such as clinker trouble in fluidized bed gasifiers, sintering in stoker combustors, agglomeration in fluidized bed combustors, fouling of heating surface in combustors, vaporization of harmful elements from the ash. Therefore, prediction of ash behavior is of vital importance, particularly for combustion systems In fluidized bed combustion systems, agglomeration (sintering) of ash (coal) and bed material particles can cause severe problems. As a result of agglomeration, deposition can form on heat transfer surfaces and bed walls. Accumulation of sticky ashes on surfaces can cause substantial decrease in heat transfer coefficient, disturb air distribution and consequently fluidization in the bed. In the most serious cases, sintering of particles can lead to heavy agglomerate mass which finally disturb fluidization and combustion completely. In these cases the system has to be dismantled in order to remove agglomerates and restore the normal operation. The measurement of so called characteristic ash temperatures, namely initial deformation temperature (IT), softening temperature (ST), hemispherical temperature (HT) and fusion temperature (FT) is considered to be one of the best methods to estimate the behavior of coal ash in coal combustors in practice. The agglomeration is a process which describes formation of agglomerates from particles under heating. The earlier works suggest that, in fluidized bed combustors, agglomeration can occur as a result of partial melting and stickiness of bed particles due to the operating of fluidized bed at temperatures higher than the melting point of coal. But later research indicate that agglomeration can occur at temperatures much lower than the ash fusion temperature. The temperature at which agglomeration starts is called first sintering temperature. The properties and behavior of ashes are remarkably different among coals and since coal ash is extremely complex mixture of minerals it is not possible to predict the fusion behavior of such mixture from its chemical composition with a reasonable accuracy. Many correlations have been developed to estimate the softening and fusion behavior of ashes from their chemical composition, in general, all of them suggest that the softening and fusion temperatutes increase as the amounts of asidic oxides (SİO2, AI2O3) in the ash increase. Therefore, it is essential to study the individual coal deposit in order to see how they exactly behave in practical combustion. The objectives of this work is to determine the characteristic ash temperatures of some major Turkish lignites, to investigate the relationship between their temperatures and inorganic compositions and relationship between ash fusiontemperatures and inorganic compositions and relationship between ash fusion temperature and agglomeration temperature of some selected coals. The effect of addition of some metal oxides which are the major component of ashes of coals on the characteristic temperatures is also investigated. Ten coal samples studied were taken from the major lignite deposits in various districts of Turkey. One sample out of ten is oil shale. The samples are ; 1 ) Beypazarı - Ankara 2 ) Çan - Çanakkale 3 ) Elmalı ( Soma ) - Manisa 4 ) Eynez - Manisa 5 ) Deniş ( Soma ) - Manisa 6 ) Göynük - Bolu 7 ) Göynük Oil shale - Bolu 8 ) Kısrakdere - Manisa 9 ) Tunçbilek - Kütahya 10) Yatağan - Muğla The following analyses were carried out in order to characterize coal samples and ashes : Proximate analysis, elemental analysis, measurement of characteristic temperatures and chemical analysis of ashes. Coal samples were crushed and sieved to - 200 mesh and ashes were prepared using the TS 330 procedures. Ash compositions were determined according to ASTM procedure D 2795 - 86. Ash fusion measurements were made by using a LECO AF - 500 type ash fusion furnace with digital read - out, sensivity of 5K and a maximum temperature of 1844 K according to the ASTM procedure D 1857 - 68. Ash cones were prepared and put into the furnace and were heated to the fusion temperature with a heating rate of 8 K/ min. under oxidizing gas atmosphere. The results are presented as the an average values of repeated measurements. The results of chemical analysis of ashes and ash fusion measurements are presented in Table 1 and Table 2 respectively. As seen from Table 2, initial deformation temperatures and fusion temperatures of lignites change between 1377 - 1573 K and 1482 - 1844 K, respectively. The fusion temperature of Eynez lignite was out of the temperature range of ash fusion furnace and it could not be measured exactly. Comparison of Table 1 and Table 2 indicated that, in general, coals with higher Si02 and lower Fe203 contents such as Eynez, Elmalı, Kısrakdere, Tunçbilek and Yatağan lignites have higher initial deformation and fusion temperatures while coals with higher Na20 percentages have lower fusion temperatures. However, no regular relationship is seen between chemical composition and critical temperatures of ashes. For example, in spite of their high Na20 percentages, Eynez, Kısrakdere and Tunçbilek lignites have fusion temperatures higher than that those with lower Na20 percentages. In Figure 1, the initial deformation temperatures are given as a function of total percentage of (Na20 + K20 + CaO + MgO). These oxides are called basic oxides which are considered, chemically, to be the most active components and have the leading role in agglomeration (sintering) behavior of ash. It is clear from figure that no regular relationship between composition and deformation temperature can bedescibed for original coal ashes. The initial deformation temperature differs widely even for ashes having nearly the same total basic oxide percentage. A set of experiments was carried out by using of Na2C03, K2CO3, CaO and MgO as additives to ashes in order to investigate the relationship between the X U.m&<*J..lIX-/.CA,I1^-TVJX^VS^IT : Initial deformation temperature, ST : Softening temperature, HT temperature, FT :Fusion temperature. Hemispherical composition and fusion charteristics for the individual ashes. In these experiments, CaO and Na20 contents of all ashes were increased by adding of CaO and Na2C03. K2C03 and MgO were added only to Beypazarı lignite ash. The characteristic temperatures of Beypazarı Elmah, Eynez, Tunçbilek and Yatağan lignites and Göynük oil shale decreased regularly with increasing CaO content while no considerable changes was observed for other lignites. A maximum decrease of 130 K was determined in fusion temperature with an increase of 9% in CaO for Eynez and Yatağan lignites. The Na20 content of ashes was increasd by using Na2CÛ3. Increasing of the amount of Na20 lowered the characteristic temperatures of Beypazarı, Çan, Eynez, Kısrakdere, Tunçbilek and Yatağan lignite ashes. Temperature profiles of Elmah XIlignite ash had a minimun around 8% Na20 below which temperatures decreased while above which increased slightly with increase in Na20 contest. Increasing of Na20 content by 10%, caused a 120 K and 180 K reduction in fusion temperatures of Beypazarı and Eynez lignite, respectively, which were the highest reductions determined. Other ashes were not affected significantly by the Na20. 10 15 20 25 30 %{CaO+ MgO+ Na20+ K20} 35 40 Figure 1. Change of fusion temperature of oginal coal ashes with (Na20 + K20 + CaO + MgO) % Another topic studied in this work is the relationship between the agglomeration and characteristic temperatures of lignites. For this purpose, a set of experiments was performed in which the agglomeration temperatures (Tag) of Beypazarı, Çan, Eynez, Kisrakdere, Göynük and Yatağan lignites were determined in a 10 cm id fluidized bed combustor. Results of agglomeration measurements are compiled in Table 3. The difference between agglomeration temperature and characteristic temperatures are also included in the Table. The differences described as AT, = IT - Tag, AT2 = ST - TAG, AT3= HT - TAG, AT4 = FT - TAG Agglomeration tempertures listed in Table 3 are lowest temperatures where first agglomerates formed. Data in the table indicate that agglomeration of lignite can occur at temperatures several hundred degrees below fusion temperature for a lignite in a fluidized bed coal combustor. Values of ATi, AT2, AT3 > AT4 show that the agglomeration behavior of lignites with different ash compositions vary widely and can not be explained on the basis of ash fusion temperature. XIITable 3. Agglomeration Temperature of Some Lignites. X1U ÖZET Kömür yakma sistemlerinde karşılaşılan sinterlesme ve aglomerasyon olayları, yanmanın sürekliliği açısından problem yaratmakta ve sistemin verimim olumsuz yönde etkilemektedir. Aglomerasyon, kül taneciklerinin birbirine yapışıp, katı bir kütle haline gelmesi olayıdır ve özellikle akışkan yataklı yakma sistemlerinde karşılaşılan önemli bir. problemdir. Temel olarak kömürün anorganik yapı özelliklerinden kaynaklanmaktadır. Bu nedenle JmL ergime sıcakhldarı ve aglomerasyon özellikleri arasında bir etkileşim olduğu sarınmaktadır. Bu çalışmada, 9 linyit ile bir bitümlü şistin küllerinin anorganik yapılan ile özgül sıcaklıkları olarak bilinen, başlangıç deformasyon (İT), yumuşama (ST), yan küreselleşme (HT) ve akma {FT) sıcaklıkları arasındaki ilişki incelenmiştir. Çalışmada, hem orjinal, hem de belirli oranlarda, Na2C03, K2C03, CaO ve MgO katılarak bileşimleri değiştirilmiş olan `katkılı küller` göz önüne alınmıştır. Küllerin anorganik yapılan, standart yöntemler kullanılarak belirlenmiştir. Özgül sıcaklıkları LECO AF 500 model bir cihaz kullanılarak, ASTM D 1857 ' ye göre oksitleyici atmosferde ölçülmüştür. Aglomerasyon sıcaklıkları ise 10 cm çapında bir akışkan yatakta ölçülmüştür. Orjinal küllerin İT değerleri 1377-1576 K, ST değerleri 1414-1801 K, HT değerleri 1460-1814 K, FT değerleri 1482- 1844 K arasında değişmektedir. Özgül sıcaklıkları en yüksek olan kömü Eynez linyiti, en düşük olan ise Göynük bitümlü şisti olmuştur. Orjinal küllerin anorganik yapılan ile özgül sıcaklıklan arasında sistematik herhangibir ilişki görülmemiştir. Genel olarak, Na20 içerikleri yüksek olan kömürlerin çoğunlukla daha düşük sıcaklıklarda, buna karşın SİO2 oranlan yüksek ve Fe203 oranlan düşük kömürler ise daha yüksek sıcaklıklarda ergimiştir. Ancak bu durum incelene bütün kömürler için, geçerli değildir. Aynı tür küllerin yapısal değişimlerini özgül sıcaklıklara etkisini görmek amacıyla, bazı küllere değişik oranlarda Na2C03, K2CO3, CaO ve MgO katılarak hazırlanan katkılı küllerle yapılan ölçümlerin sonuçlan, sıcaklıklan en fazla etkileyen katkının Na2C030İduğunu göstermiştir. Toplam Na20 içeriğine bağlı olarak, özgül sıcaklıklarda genelde bir düşme eğilimi gözlenmiştir. Na20 katkısı bazı kömürlerin ergime sıcaklıklarını 120 K kada^düşürmüştür. Kömürlerin aglomerasyon sıcaklıkları, deformasyon sıcaklıklarına (IT) allında kalmaktadır. Aglomerasyon sıcaklıkları İT değerlerinden 175-346 K, ergime sıcaklıklarından ise, yaklaşık olarak 346-551 K daha düşük olmuştur. Akışkan yataklarda yanan kömür taneciklerinin sıcaklığının ölçülen ortalama yatak sıcaklığından yaklaşık olarak, 100-150 K daha yüksek olduğu göz önüne alındığında, aglomerasyonun deformasyon sıcaklığında veya ona çok yalan sıcaklık seviyelerinde başladığı anlaşılmaktadır. 79

ÖZET Bu çalışmada yeni bir güneşli hava ısıtıcısı geliştirilmiş ve verim deneyleri ile performansı incelenmiştir. Tarımsal ürünlerin hijyenik bir ortamda, güneş enerjisinden etkin bir şekilde yararlanarak kurutulması amacıyla geliştirilen model bir kurutucuda çeşitli sebze ve meyveler kurutulmuştur. Çeşitli hava debilerinde gerçekleştirilen deneylerden elde edilen sonuçlar, aynı ürünlerin açık havada da kurutulması ile elde edilen sonuçlarla karşılaştırılmıştır. ABSTRACT In this study, a new solar air heater is developed and bjft using the efficiency measurement and calculation results its performance is analyzed. In order to make the agricultural products dry in the hygenic conditions, and also to use the solar radiation effectively, a model drying bin is. constructed and applied to the solar air heater and to check the realisation the aim, some of vegetables and fruits are dried. The experimental results are compared with the simulta neous drying processes in the atmospheric conditions of the same kind of agricultural products. ÖZET Bu çalışmada yeni bir güneşli hava ısıtıcısı geliştirilmiş ve verim deneyleri ile performansı incelenmiştir. Tarımsal ürünlerin hijyenik bir ortamda, güneş enerjisinden etkin bir şekilde yararlanarak kurutulması amacıyla geliştirilen model bir kurutucuda çeşitli sebze ve meyveler kurutulmuştur. Çeşitli hava debilerinde gerçekleştirilen deneylerden elde edilen sonuçlar, aynı ürünlerin açık havada da kurutulması ile elde edilen sonuçlarla karşılaştırılmıştır. ABSTRACT In this study, a new solar air heater is developed and bjft using the efficiency measurement and calculation results its performance is analyzed. In order to make the agricultural products dry in the hygenic conditions, and also to use the solar radiation effectively, a model drying bin is. constructed and applied to the solar air heater and to check the realisation the aim, some of vegetables and fruits are dried. The experimental results are compared with the simulta neous drying processes in the atmospheric conditions of the same kind of agricultural products Bu tezin, veri tabanı üzerinden yayınlanma izni bulunmamaktadır. Yayınlanma izni olmayan tezlerin basılı kopyalarına Üniversite kütüphaneniz aracılığıyla (TÜBESS üzerinden) erişebilirsiniz.

ÖZET Bu çalışmada yeni bir güneşli hava ısıtıcısı geliştirilmiş ve verim deneyleri ile performansı incelenmiştir. Tarımsal ürünlerin hijyenik bir ortamda, güneş enerjisinden etkin bir şekilde yararlanarak kurutulması amacıyla geliştirilen model bir kurutucuda çeşitli sebze ve meyveler kurutulmuştur. Çeşitli hava debilerinde gerçekleştirilen deneylerden elde edilen sonuçlar, aynı ürünlerin açık havada da kurutulması ile elde edilen sonuçlarla karşılaştırılmıştır. ABSTRACT In this study, a new solar air heater is developed and bjft using the efficiency measurement and calculation results its performance is analyzed. In order to make the agricultural products dry in the hygenic conditions, and also to use the solar radiation effectively, a model drying bin is. constructed and applied to the solar air heater and to check the realisation the aim, some of vegetables and fruits are dried. The experimental results are compared with the simulta neous drying processes in the atmospheric conditions of the same kind of agricultural products. ÖZET Bu çalışmada yeni bir güneşli hava ısıtıcısı geliştirilmiş ve verim deneyleri ile performansı incelenmiştir. Tarımsal ürünlerin hijyenik bir ortamda, güneş enerjisinden etkin bir şekilde yararlanarak kurutulması amacıyla geliştirilen model bir kurutucuda çeşitli sebze ve meyveler kurutulmuştur. Çeşitli hava debilerinde gerçekleştirilen deneylerden elde edilen sonuçlar, aynı ürünlerin açık havada da kurutulması ile elde edilen sonuçlarla karşılaştırılmıştır. ABSTRACT In this study, a new solar air heater is developed and bjft using the efficiency measurement and calculation results its performance is analyzed. In order to make the agricultural products dry in the hygenic conditions, and also to use the solar radiation effectively, a model drying bin is. constructed and applied to the solar air heater and to check the realisation the aim, some of vegetables and fruits are dried. The experimental results are compared with the simulta neous drying processes in the atmospheric conditions of the same kind of agricultural products Bu tezin, veri tabanı üzerinden yayınlanma izni bulunmamaktadır. Yayınlanma izni olmayan tezlerin basılı kopyalarına Üniversite kütüphaneniz aracılığıyla (TÜBESS üzerinden) erişebilirsiniz.