Investigation of the effects of different drying methods on coal grindability and desulfurization
[ X ]
Tarih
2019
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Adana Alparslan Türkeş Bilim ve Teknoloji Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Alternatif kaynaklar önerilmesine rağmen kömür halen en çok tüketilen fosil yakıtların başında gelmektedir. Kömürlerin kullanıma hazırlanması işlemleri sırasında termik santrallerde tüketilen enerjinin çok önemli bir kısmı öğütülme işlemleri sırasında harcanmaktadır. Bu sebeple, kömürlerin öğütülme işlemi sırasında harcanan enerjinin azaltılmasını sağlayacak yardımcı ön işlemlere gerek duyulmaktadır. Geleneksel kurutma yöntemlerinde kömürde ve yapısında bulunan su ve kömürün kendisi de ısınmaktadır. Mikrodalga ile kurutmada ise ısınma mekanizması farklıdır ve yalnızca kömürün içerdiği su ısınmakta ve faz değiştirerek kömürün yapısından uzaklaşmaktadır. Ön ısıl işlemler sırasında kömürlerin yapısında gerilmeler ve çatlaklar meydana gelmekte ve bu gerilmeler ile birlikte kırıklar ve çatlaklar artmaktadır. Oluşan bu yapı kömürleri öğütmeye karşı daha az dirençli hale getirmektedir. Isıtma işlemleri arasında hızlı ısıtma kapasitesi ve farklı malzemeler üzerindeki seçici ısıtma özelliği ile mikrodalga enerjisi dikkat çeken bir ısıtma işlemi olarak görülmektedir. Kömürlerin öğütülebilirliğini etkileyen faktörlerden kömürün nem oranı, petrografik birleşimi ve yaşı önemli rol oynamaktadır. Ön ısıtma işlemine tabi tutulan kömürlerin öğütülebilirlikleri olumlu yönde etkilenmekte ve boyut küçültme işlemlerini kolaylaştırabileceği bilinmektedir. Bu çalışmada geleneksel kurutma yöntemleri (sabit ısıtmalı fanlı hava sirkülasyonlu etüv, havada kurutma) ile mikrodalgada kurutmanın kömürün öğütülebilirliğine olan etkileri ve ilişkileri araştırılmıştır. Bu amaçla iki farklı linyit kömürü; Tufanbeyli ve Ilgın linyit kömürleri seçilmiştir. Araştırma parametreleri olarak; kurutma tipi, kurutma sıcaklığı, kurutma süresi bağımsız değişkenler olarak seçilmiştir. Aynı koşullarda çubuklu değirmende öğütülmüş numunelerin tane boyu dağılımları; d50 ve d80 değerleri ise bağımlı değişken olarak kabul edilmiştir. Yapılan deneysel çalışmalar sonucunda havada kurutma ve etüvde kurutma metodu ile yapılan deneylerin sonucuna kıyasla mikrodalga kurutma yöntemi uygulanan linyit kömürlerinin öğütülmesi daha kolay olduğu ve kurutmanın kömür öğütülebilirliğini artırdığı saptanmıştır. Ayrıca Tufanbeyli ve Ilgın kömürlerinin asidik ve bazik ortamda kimyasal çözündürme yöntemiyle kükürt giderimi araştırılmıştır. Kükürt giderimi deneylerinde araştırma parametreleri olarak; sıcaklık ve reaksiyon süresi bağımısız değişkenler olarak seçilmiştir. Aynı katı oranı, tane boyutu ve asit konsantrasyonu koşullarında yapılan kimyasal çözündürme deneylerinde kükürt giderimi ise bağımlı değişken olarak belirlenmiştir. Yapılan kükürt giderimi deneyleri sonucunda her iki linyit kömürü için de asidik ortamda sıcaklık arttıkça kükürt gideriminin arttığı, bazik ortamda ise sıcaklık arttıkça kükürt gideriminin azaldığı saptanmıştır. Anahtar Kelimeler: Kömür, Linyit, Kömür kurutma, Mikrodalga enerji, Öğütülebilirlik, Kükürt giderimi
Although there are some alternative energy-supplier-materials to coal, coal is one of the most used fossil energy containing material in the world. Much of the energy consumed in thermal power plants is used during the grinding process of coals. For this reason, pre-treatment processes are required to reduce the energy consumed during the grinding of coals. In conventional drying methods, the water in the coal and its structure is directly heated. On the other hand, in the case of microwave drying, only the water contained in the coal is heated and changed the phase and away from the structure of the coal. During the preheating process, stresses and cracks form in the structure of the coal and fractures and cracks increase depending on the amount of those stresses. The resulting structure makes the coal less resistant to crushing and grinding. Microwave energy is considered to be a remarkable heating process with fast heating capacity among heating operation techniques and can heat the different materials selectively. The factors affecting the grindability of the coals are the moisture content, petrographic composition and rank of the coals. The grindability of the pre-heated coal is assumed to be positively affected and facilitates size reduction processes. In this study, effects and relationship of traditional drying methods (air circulated fan oven and air drying) and microwave drying on the grindability of coals were investigated. For this purpose two different lignite coal; Tufanbeyli and Ilgın lignite coals were selected. The research parameters; drying method, drying temperature, drying time were selected as independent variables. The particle size distributions of ground coal samples in a rod mill, under the same conditions were determined. The particle size distribution, d50 and d80 values of the ground coals were considered as dependent variables. As a result of the experimental studies, it was found that lignite coal grinding was easier with microwave drying compared to the results of experiments with air drying and oven drying and drying increases the coal grindability. In addition, desulfurization of Tufanbeyli and Ilgın coals was also investigated by chemical dissolution in acidic and basic media. In desulfurization experiments the research parameters; temperature and reaction time were selected as independent variables. Sulfur removal was determined as the dependent variable in the chemical dissolution experiments performed under the same solid content, particle size and acid concentration conditions. As a result of the desulfurization experiments for both lignite coals, the desulfurization increased as the temperature increased in acidic media and the desulfurization decreased as the temperature increased in alkaline media. Keywords: Coal, Lignite, Coal drying, Microwave energy, Grindability, Desulfurization
Although there are some alternative energy-supplier-materials to coal, coal is one of the most used fossil energy containing material in the world. Much of the energy consumed in thermal power plants is used during the grinding process of coals. For this reason, pre-treatment processes are required to reduce the energy consumed during the grinding of coals. In conventional drying methods, the water in the coal and its structure is directly heated. On the other hand, in the case of microwave drying, only the water contained in the coal is heated and changed the phase and away from the structure of the coal. During the preheating process, stresses and cracks form in the structure of the coal and fractures and cracks increase depending on the amount of those stresses. The resulting structure makes the coal less resistant to crushing and grinding. Microwave energy is considered to be a remarkable heating process with fast heating capacity among heating operation techniques and can heat the different materials selectively. The factors affecting the grindability of the coals are the moisture content, petrographic composition and rank of the coals. The grindability of the pre-heated coal is assumed to be positively affected and facilitates size reduction processes. In this study, effects and relationship of traditional drying methods (air circulated fan oven and air drying) and microwave drying on the grindability of coals were investigated. For this purpose two different lignite coal; Tufanbeyli and Ilgın lignite coals were selected. The research parameters; drying method, drying temperature, drying time were selected as independent variables. The particle size distributions of ground coal samples in a rod mill, under the same conditions were determined. The particle size distribution, d50 and d80 values of the ground coals were considered as dependent variables. As a result of the experimental studies, it was found that lignite coal grinding was easier with microwave drying compared to the results of experiments with air drying and oven drying and drying increases the coal grindability. In addition, desulfurization of Tufanbeyli and Ilgın coals was also investigated by chemical dissolution in acidic and basic media. In desulfurization experiments the research parameters; temperature and reaction time were selected as independent variables. Sulfur removal was determined as the dependent variable in the chemical dissolution experiments performed under the same solid content, particle size and acid concentration conditions. As a result of the desulfurization experiments for both lignite coals, the desulfurization increased as the temperature increased in acidic media and the desulfurization decreased as the temperature increased in alkaline media. Keywords: Coal, Lignite, Coal drying, Microwave energy, Grindability, Desulfurization
Açıklama
Fen Bilimleri Enstitüsü, Nanoteknoloji ve Mühendislik Bilimleri Ana Bilim Dalı
Anahtar Kelimeler
Mühendislik Bilimleri, Engineering Sciences
