Solids handling – learning the lessons

Richard Farnish, consultant engineer at the Wolfson Centre, discusses best practice in bulk handling system design and operation:

London – With ever increasing commercial pressures to optimise productivity the focus of attention for many companies is frequently turning to improving their understanding of the fundamentals of best practice in bulk solids handling technologies. 

A problem that has existed for many companies is identifying sources of independent training in a subject area that is still perceived by many as a “black art”.  What is often not appreciated by engineers is the wealth of information that has been developed since the 1960’s that can be usefully applied to address the vast majority of bulk handling issues. 

The sheer diversity of industries that handle powders or granular materials in bulk as part of their production dictates that some problems tend to be very process/product specific.  However, common themes that engineers must contend with include; poorly discharging vessels, variable blend composition, bulk density variation, particle attrition, caking, segregation or unreliable pneumatic conveying systems. 

The common element that brings these types of problems together for a very wide range of industries is the inefficiencies associated with the presence of any one of these issues within a process – resulting in down time, reject (OOS) product or excessive energy consumption.

One of the significant barriers to a more widespread understanding of bulk granular or powdered materials lies in the simple issue of access to reference materials.  Unfortunately, the paucity of material reflects the poor representation of the subject in the majority of academic institutions around the world.  

The lack of even a rudimentary introduction to the subject for many engineers during their formal education, dictates that most knowledge is garnered from “in-plant” experience or trial and error. 

While the former avenue of knowledge carries process specific merit, the trend for down-sizing (typically through early retirement) leaves plants vulnerable to a considerable skills gap when experienced staff leave.  Additionally, previous experience may not be of much help when a new process or product is being considered.

Even a fundamental understanding of the factors that contribute to many of the common processing problems can be of considerable use to engineers.  A recognition that more needs to be known to obtain a satisfactory outcome offers significant benefits over not realising that there actually is prior knowledge to fall back on.

A diverse range of courses exist for engineers to gain insight into improving process efficiency.  The scope for plant or process refinement arising from such courses can offer very rapid payback.