Oblong delikli eleklerin çekiçli değirmenlerin performans karakteristikleri üzerine etkisi

Bu çalısmada, yuvarlak delikli eleklere karsı oblong delikli elek kullanımının, çekiçli değirmenlerin performans karakteristikleri üzerine etkisi arastırılmıstır. Denemelerde, delik çapı 2.5, 4.5 ve 6.5 mm olan yuvarlak delikli elekler ile delik ölçüleri 19.8x1.5, 19.8x2 ve 19.8x2.5 mm olan oblong delikli elekler kullanılmıstır. Materyal olarak, sert beyaz buğdayın kullanıldığı öğütme islemleri, her bir elek için 5 faklı çekiç çevre hızında yapılmıstır. Arastırma sonuçları, öğütme sonrası elde edilen ürünlerin, ortalama geometrik çap, geometrik standart sapma ve özgül yüzey alanı değerlerinin, elek tiplerine göre farklı olmakla birlikte, elek delik büyüklüğü ve çekiç çevre hızına bağlı olarak değistiğini göstermistir. Her iki tip elekle yapılan öğütme sonrası, elde edilen örneklerin partikül büyüklük dağılımları, birbirine yakın bulunmustur. Yine, her iki elek grubunda da, öğütme kapasitesinin, elek delik büyüklüğü ve çekiç çevre hızına bağlı olarak değistiği, oblong delikli eleklerin, özellikle yüksek çekiç çevre hızlarında, öğütme kapasitesini önemli düzeyde arttırdığı saptanmıstır. Özgül yüzey alanı 3.37-4.60 m2kg-1 arasında değisen ürünlerin, oblong delikli eleklerle 70-80 ms-1 çekiç çevre hızlarında öğütülmesinin, yuvarlak delikli eleklere göre, öğütme etkinliğini önemli düzeyde arttırdığı belirlenmistir.

The effect of oblong holed screens on performance characteristics of hammer mill

In this study, the effect of oblong-holed screen usage instead of round-holed screens on performance characteristics of hammer mill was investigated. In the experiments, hole diameters of 2.5, 4.5 and 6.5 mm for round-holed screens and hole dimensions of 19.8x1.5, 19.8x2 and 19.8x2.5 for oblong-holed screens were used. As material, grinding procedures carried out for each screen were performed at five different hammer tip speeds for grinding white hard wheat. Results obtained from the present study showed that mean geometric diameter, geometric standart deviation and specific surface area of the products differed significantly depending on screen types as well as showing variations with changing screen hole sizes and hammer tip speeds. It was also found that products from both screens types showed similar particle size distribution. Moreover, grinding capacity for both screen types varied with screen hole size and hammer tip speed. On the other hand, oblong-holed screens increased markedly grinding capacity especially at higher hammer tip speeds. Grinding with oblong-holed screens at hammer tip speeds of 70-80 ms-1 instead of using round-holed screens gave much higher mill efficiency for products having specific surface areas from 3.37 to 4.60 m2kg-1.

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