Hopper angles
Whenever the size of a chute, silo, storage is changing its geometry, a hopper or transition is needed. With the change of geometry or size it results in non-vertical surfaces that are building obstacles to the flow of bulk solids.
When talking about these transitions, then they can have many different shapes and can also change shape as very typical are changes from round to rectangle on silos, or the other way round from process equipment in to pipe runs. ?
Lets look at a rectangular change in cross section. In such a case you can have 3 different angles in the hopper. The side angles A and B are quite obvious and easy to understand. However, the tricky one is the valley angle which is a angel that is a result of the 2 side angles as people put the main attention to the side angle. As the corners of the hopper are in general more sensitive to agglomerations and bridging the a wrong valley angle can be the source of flow issues in a transition or discharge.
As height of such a transition is often an issue so that they should be as small as possible, getting the angles right can therefore be crucial.
In those cases where space is critical and things need to be optimized, I highly recommend to consult experts in this field which will help you to get around those things without any headache. I can also recommend outstanding literature “Storage and Flow of bulk solids” from Greg Mehos (https://mehos.net/) about this topic.
Next time, we’ll discuss what mass flow in bulk solids means.
As always, please do not hesitate to message me with questions/comments.