Bates L.,Ajax Equipment Ltd. |
Dhodapkar S.,Dow Chemical Company |
Klinzing G.,University of Pittsburgh
Chemical Engineering | Year: 2010
We have presented a brief overview of an extensive but largely under-developed technology of bin inserts. Application of fundamental concepts of powder mechanics and good engineering practices, driven by ingenuity, are key to future innovations in this field.
McGee E.,Ajax Equipment Ltd. |
Bates L.,Ajax Equipment Ltd.
Bulk Solids Handling | Year: 2014
Controlled discharge of bulk solids from hoppers and silos is achieved by using a properly designed feeder. In many installations the feeder is required to serve an opening size considerably greater than the critical arching dimensions of the bulk solid so that flow from the hopper is guaranteed. In some circumstances when a change of use is considered the new bulk solid may have characteristics selected for improved flow reliability reasons but these can lead to larger than expected loads at the hopper outlet. The feeder can be subject to quite high overpressures from the hopper contents which can impose heavy shear loads on the feeder. Efficient sizing will limit the load on the feeder and the feeder's capital cost. The forces acting through the outlet of a bulk storage hopper that has developed a fully mobilised mass flow regime are favourable for reducing the load on the feeder and can be considered to have two components: - that resulting from carrying the unsupported mass underneath the dynamic arch and the extra overpressure resulting from the degree by which the stress developed in the dynamic arch exceeds the unconfmed failure stress because the size of the outlet is greater than the critical arching span. Of course to provide an effective mass flow regime it is essential to provide progressive extraction along the hopper outlet slot and generate a shear plane that expands in the direction of travel to relieve the 'pull-out force' needed by allowing for expansion and the change of flow direction. This paper presents design considerations for the effects on the load exerted on the feeder based on an examination of the hopper outlet geometry and thefrictional and shear characteristics of the stored bulk solid with particular reference to the load due from material underlying the arch.
Mcgee E.,Ajax Equipment Ltd. |
Picking K.,Tata Steel
Bulk Solids Handling | Year: 2012
An innovative technique developed by solids handling equipment specialist, Ajax Equipment, uses a multiple stage insert system to overcome bunker flow problems in coal mining operations. This innovative technique creates a more favorable approach to existing outlets and spreads the flow to previously 'dead' storage areas of the bunker. The insert system has been used at Tata Steel Europe's plant in Scunthorpe, UK, to overcome coal bunker flow problems. Inserts offer the opportunity to generate slip more easily at the walls, converting the axial-symmetric flow to planar flow type, which is a more favorable, flow form and shields the outlet region to reduce consolidating stresses. This results in material flowing more readily, along with a reduction in the tendency to form a stable arch or rat hole. Flow modifying inserts take many forms from a simple lining system, which offers lower wall friction through to multi-stage systems with varying wall profiles and static inserts.