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LACK OF BEST PRACTICE FOR BULK SOLIDS HANDLING IN PROCESS PLANTS – ARE THE LESSONS BEING LEARNT?

bulk solids handling

One observation that can be made with some certainty is that many of the common bulk solids handling issues that have inhibited process efficiency for many decades are still with us.  This is a daily fact of operational life for all sectors of manufacturing irrespective of how comprehensive the “high tech” veneer is for the company image.

Production problems such as discharge stoppages from silos, metering accuracy fluctuation, product quality variation, etc are still very much in evidence – despite the establishment of design techniques to avoid these issues over 50 years ago (Figs 1, 2 & 3).  The question that industry should be asking itself is – how has this disconnect between available design methodology and uptake arisen?  

It is an unfortunate fact that most educational routes for engineers (process, mechanical or chemical) will have included no formal exposure to the science of transporting and storing of granular or powdered materials, but almost certainly would have included education in fluid dynamics (a medium far more forgiving and predictable in its behaviour!).  Part of the problem with educational provision for bulk solids handling can probably be attributed to the fact that it is a subject area that does not lend itself well to being “pigeon holed” to any one engineering discipline.  The reality of the situation is that it embodies elements of Mechanical, Physics, Chemical and Process Engineering – and it is probably as a consequence of this that it has remained in the margins of formal education for the last five decades.  Whatever the reasons for its absence from the majority of Universities around the world, the nett result is that the industries that depend heavily upon correct bulk handling for their process are commonly working with equipment that has shown minimal fundamental design evolution for many decades.  Most advances in bulk solids handling (in the commercial field) have been derived from empirical experience which, although delivering improvements in some technical areas, is not a development route usually noted for yielding fundamental advances.  The industry and its equipment provision remain highly conservative in this respect.

Where the industry should be
The key issue for many engineers in industry is not that they don’t know anything about bulk materials (they work with them most days!), but that due to the lack of education provision they don’t know what it is that they don’t know.  In a nutshell most of the working knowledge relating to bulk materials within a company is often a distillation of experiences built-up over the years by operators and engineers.  Again this leads to a situation whereby new blends or formulations are assessed on the basis of performance of past (“similar”) materials.  This concept can (and often does) lead to unanticipated processing problems due to a material “similarity” having been assessed from a specification sheet or a cursory visual inspection rather than a physical bulk property measurement.

Processes that have dry bulk solids handling at their core are notorious for commissioning and resulting financial overruns.  In most cases these issues are directly attributable to a lack of investment of resources at the outset of the project to take time to understand the storage and/or handling characteristics of the materials to be processed.  It is very easy for the short term objectives of getting a piece of equipment or process up and running in as short a time as possible to dominate procurement procedures and specification writing.  However, the need for a quick turn around to projects combined with (typically) restricted CAPEX mean that many purchases are evaluated predominantly on cost.  The potential problem arising form this common scenario is that the true cost of many such purchases only becomes apparent in form of protracted start-up time, inability to perform at rate throughputs or plant down time through stoppages.  These additional, and often significant costs, are typically lost to the direct accounting process within the all encompassing maintenance budgets many plants operate with.  Thus the true cost to the plant of a poorly specified / designed equipment or system is lost from the balance books.  It is no wonder that without the availability of financial justification for selecting more technically robust equipment, the same types of problem are doomed to be repeated over.  

The financial motivation for industry to move forwards (technically) has never been stronger than it is in today’s highly competitive markets.  The pressure to minimise wastage, increase quality and maximise profitability would normally be the catalyst for innovation – but is being held back by a lack of basic knowledge of bulk solids handling.  

The way forward must be to improve the educational provision for engineers working in both manufacturing industries and the equipment suppliers.  It is difficult to see any radical changes coming soon, but many industry associations such as the Solids Handling and Processing Association (SHAPA), Materials Handling Engineers Association (MHEA), Institution of Mechanical Engineers (IMechE) and Institute of Chemical Engineers (IChemE) all hold seminars and conference events throughout the year covering background information on the range of topics associated with bulk handling.  Industrially focussed short courses are also available from research and consultancy groups such as The Wolfson Centre for Bulk Solids Handling Technology, University of Greenwich (one of only five specialist institutes around the world that actively undertake research and consultancy work in the industrial use of powdered and granular bulk materials).  

Is industry going to get there any time soon?
The basis for industry to progress from the current range of common process problems related to bulk solids must lie in developing sufficient introspection to question why such nominally simple process steps, such as getting material to flow from a silo reliably, still present seemingly insurmountable problems some 2000 years after the Egyptians were handling grain in bulk.  Possibly the fact that these types of problems are so widespread forces the conclusion that “this is as good as it gets” amongst engineers that look outside of their manufacturing sector for inspiration!

The potential return on investment for attendance at courses and professionally organised seminars can be enormous and immediate.  The information that industry needs has been in the public domain for fifty years – it is for today’s engineers to use the knowledge that is currently available and start to bring improvements before the next fifty years pass by.

“There is nothing in the world that some man cannot make a little worse and sell a little cheaper, and he who considers price only is that man”s lawful prey.”  
John Ruskin 1819 -1900

By Richard Farnish, Mphil CEng MIMechE – Consultant Engineer – The Wolfson Centre For Bulk Solids Handling Technology

References

Solids Handling and Processing Association (SHAPA)
http://www.shapa.co.uk/

Materials Handling Engineers Association (MHEA)
www.mhea.co.uk/

Institution of Mechanical Engineers (IMechE)
www.imeche.org/knowledge/industries/process-industries/overview

Institute of Chemical Engineers (IChemE) –

The Wolfson Centre for Bulk Solids Handling Technology
www.bulksolids.com

The Wolfson Centre for Bulk Solids Handling Technology
University of Greenwich
Central Avenue
Chatham
Kent

Can be contacted on

+44 (0) 208 331 8646
[email protected]
Web: www.bulksolids.com

Process Industry Informer

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