Delft University of Technology
Faculty Mechanical, Maritime and Materials Engineering Transport Technology
T. Verheijen Stability mechanism for an auger frame inside a Eurosilo.
Engineering Assignment, Report 2006.TL.7094, Transport Engineering and Logistics.
Bulk solids can be stored space effectively in a Eurosilo. Augers are used to spread and remove the bulk solids inside the Eurosilo. The augers are placed in an auger frame, which is suspended by steel cables from the bridge. In an aboveground Eurosilo the auger frame is guided against the silo wall. Because of the rough wall surface of an underground silo, guiding the auger frame against the wall is not possible. In the past, Eurosilo has used a central pillar to guide the auger frame. Because of asymmetric pressure that the bulk solids exert to the central pillar, there is the possible risk that the pillar might buckle. As guiding the auger frame against the wall or through a central pillar is not suitable in an underground silo, the question from ESI Eurosilo B.V. rose, whether there is another possibility to guide the auger frame. During the filling and emptying of a silo, the auger frame may swerve because of the pressure of the augers on the bulk solids and because of the rotation of these augers. As the auger frame may not touch the silo wall, the displacement of the auger frame is restricted to a maximum of 0,5 meter compared to the situation in rest.
Set by boundary conditions and assumptions, four concepts have been developed. From a multi variable analysis the Star concept proved to be most successful. The concept has been further developed and with use of Ansys, the Star concept has been analysed statically and dynamically. Static analyses only show little displacements of the auger frame. Dynamic Ansys analyses show the system has certain Eigen-frequencies at the range of the frequency of the augers. Dynamical force analyses show too high displacements of the auger frame, and as a consequence of this displacement, the auger frame could touch the wall and get damaged. The dynamic analyses thus show that the current Star concept is not a suitable alternative to guide the auger frame in an underground silo. Recommended is to further develop the dynamic Ansys model and to verify the model with a physical one.
Reports on Transport Engineering and Logistics (in Dutch)
