Stresses in Bins and Hoppers

(Use of Jenike's method for hopper design)

by Gabriel I. Tardos

Department of Chemical Engineering
The City College of the City University of New York
Convent Ave. and 140th Street, New York, NY 10031, USA
Email: Tardos@Che-mail.Engr.CCNY.CUNY.Edu
Received: 1998 December 11; Posted: 1999 April 8

Abstract: This article presents a way to predict stresses in bins and hoppers, devices most widely used in industry to store powdery materials. It employs the simplified method of integral balances -- more widely known as the method of slices -- together with Janssen's postulate that provides the required closure for the solution of the resulting balance equations. The great advantage of the procedure is its simplicity, while it's most important drawback is that the final solutions contain an adjustable parameter (Janssen's constant, K) that has to be either measured experimentally or calculated from a more advanced theory. This method is used to illustrate the design of mass-flow hoppers following Jenike's method; the design comes down to choosing the hopper angle and calculating the critical size of the hopper outlet. Also presented are some examples of measured angles of friction and Flow Functions from the literature and several solved problems. These illustrate both the use of Janssen's equations to predict stresses in the powder and also Jenike's method to design hoppers. Keywords: bin, hopper, stress, Jenike, design

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Prof. Gabriel I. Tardos received his early engineering education in Romania. He emigrated to Israel in 1973, where he continued his education and in 1978 received a Ph.D. in Mechanical Engineering. He then moved to the U.S.A. and since 1979 has dedicated his time to teaching and research in the Department of Chemical Engineering at the City University of New York. He served as chair of the department from 1987 to 1990. Professor Tardos has more than 25 years experience in the fields of particle technology and fluid-particle systems. He is involved in promoting the development of powder science in industry and academia and was the first to introduce the subject into an undergraduate chemical engineering curriculum in the U.S. He is in the process of publishing an undergraduate / graduate textbook in powder science and technology.

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