Stability mechanism for an auger frame inside a Eurosilo.
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
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)
, TU Delft