It is now more than 50 years since the publication of the rational method for design of hoppers and silos for reliable flow by engineer Andrew Jenike.
Yet still, one of the most common problems The Wolfson Centre for Bulk Solids Handling Technology troubleshoots for industry is hoppers, feeders, silos or other vessels that bridge, arch, rat-hole or otherwise fail to deliver material in a reliable and consistent way.
Invariably, this occurs because the design of the vessel was done without reference to the flow properties of the material to be discharged.
There are positive signs. A handful of well established UK equipment suppliers now use a hopper design method based on measurement of material flow properties, so they can be sure that when their equipment gets to site, it will work without problems.
Yet a large number still skip this step, supplying designs based on their ‘best guess’ of what will work and then retro-fit ‘flow aids’ on site, eg vibrators, air pads, air cannons, etc, to get it to work.
Those who have taken up the rational method have gone that way because of experience of costs incurred by not using it – warranty claims for poor performance, retro-fit costs, repeated visits to site to change things to get reliable flow. The small up-front costs for flow property measurements repay themselves quickly.
Much still remains to be done in education in this sector, to show people the value of this and other best practice methods for design.
Companies ‘in the know’ are now ahead of their competitors technologically. For this industry to be successful, many more need to take on board the lessons available through educational events such as conferences, short courses and seminars.
The lesson – take time to know your materials and design accordingly in order to obtain reliable plant operation.