An Experimental Study on the Determination of Minimum Fluidization Velocity

Abstract

Pneumatic conveying systems are widely used in a variety of industrial settings since different types of materials can be conveyed. There are some classifications of flow modes for conveying of powders and bulk solid particles based on mean particle size, density, and inter particle cohesion forces. In this paper, three different cases which are vertical (test case 1), horizontal (test case 2) and continuous conveying test case are constructed and considered in order to determine the flow modes in pneumatic conveying systems. Seven solid particles are used with the range of 200 kg/m3 < ρblp < 2400 kg/ m3 and 150 μm < dp < 2750 μm in these three cases. In vertical test set-up unstable zone and fluidized dense phase is occurred, then in the horizontal test set-up slug flow and plug flow is observed and lastly plug flow and dilute phase is occurred visually in continuous conveying test case. Finally, all obtained data are considered for the classification according to flow modes in pneumatic conveying systems. The observed flow modes are considered and tabulated with respect to all test cases.

Keywords

• Pneumatic conveying systems
• Flow modes
• Particle classifications
• Minimum fluidization velocity

Minimum Akışkanlaştırma Hızının Belirlenmesi Üzerine Deneysel Bir Çalışma

Öz

Pnömatik taşıma sistemleri, farklı türde malzemelerin taşınabilmesi nedeniyle çeşitli endüstriyel ortamlarda yaygın olarak kullanılmaktadır. Tozların ve düzensiz katı parçacıkların taşınması için ortalama parçacık boyutu, yoğunluk ve parçacıklar arası kohezyon kuvvetlerine dayalı bazı akış modları sınıflandırmaları vardır. Bu çalışmada, pnömatik taşıma sistemlerindeki akış modlarını belirlemek için dikey (test durumu 1), yatay (test durumu 2) ve sürekli taşıma test durumu olmak üzere üç farklı durum oluşturulmuş ve incelenmiştir. Bu üç test düzeneğinde 200 kg/m3 < ρblp < 2400 kg/m3 ve 150 μm < dp < 2750 μm aralığında yedi katı parçacık kullanılmıştır. Dikey test düzeneğinde kararsız bölge ve akışkanlaşmış yoğun faz oluşur, ardından yatay test düzeneğinde dalgalı akış ve tıkaç akışı gözlenir ve son olarak sürekli taşıma test durumunda görsel olarak tıkaç akışı ve seyrek fazlı akış oluşur. Son olarak, elde edilen tüm veriler, pnömatik taşıma sistemlerinde akış modlarına göre sınıflandırma için dikkate alınmıştır. Gözlemlenen akış modları, tüm test durumlarına göre dikkate alınmış ve tablo haline getirilmiştir.

Anahtar Kelimeler

• Pnömatik taşıma sistemleri
• Akış tipleri
• Parçacık sınıflandırma
• Minimum akışkanlaştırma hızı

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