Welcome To "Ask Lyn"
Hi.
I have found your site and it's seems verry interesting.
I did a lot of bulk handling projects and involve in troubleshouting
situations for many years. I think that is verry important to communicate solutions of everyone on specific problems for the progress of the overall technology. Actualy the major part of my time is dedicated to sawmills industries, and osb plant. Do you know if there is forums like yours for sawmill technology?
thanks. ■
Observations On Material Flow Characteristics
I can not match the professional abilities so remarkable in our moderators and the many professionals whom contribute to this remarkable website. Nevertheless, I am part of a team of operators running a concrete recycling plant and CR-2 Stone Crushing operation and I would like to make a few "practical" observations.
Mr. Wohlbier notes that plant designers anticipating the characteristics of the material being processes is equivelent to (may I add), an "ounce of prevention being worth a pound of cure".
My experience is that the material we process changes so often in its characteristics, including particle size, moisture content, adhesion, hardness and rate of flow through our primary crusher that a design engineer would be sorely tested to create a design that could accomendate this variability.
I would like to offer the comment that while this forum focuses so much on the capability of the equipment, not to be overlooked is the practicle ability needed by plant and process operators to recognize alterations in material characteristics as well as flow characteristics and be able to anticipate the outcomes associated with these changes, to modify within the limits of the machinery the process, so to rectify the difficulty anticipated because of chnges in material flow. (Whew!)
This obviously requires individuals whom through experience or education have been familiarized with the characteristics of the materails that they are transporting or processing.
It is my experience that for many of us charged with the responsibility of processing materials that the most practical solution to maintanning plant operation and process is to have feed back from the mechanicals that we are controling.
Simplicy dictates.
An operator needs amp guages which tell the operator the load at each particular electric motor at particular conveying points which an operator might respond to in rectifying potential problems prior to their occurring.
I am a proponent of belt weighers which allow an operator to see the material flow via quantification rather than a visual reference. Numbers are far better suited to establish capasity ranges than are visional references that are more subjective than absolute.
One of our biggest problems exist at transfer stations where material changes direction or elevation from one conveyor to another. (I've noted on this website several comments regarding the lack of sicentific method being applied to transferboxes so to maximized their efficiency).
The biggest increase in production might be discovered via early segregation of product according to its size.
I can not stress how much material that could be routed into storage via a duel conveying system which instead is tranported vertically in a completely unnessary step (saving in grade resistence as well as rolling resistence).
In general these materials are the greatest contributors to the problems we operators experience such as plugs which stop process, and this is due mostly to the adhesion factor associated with fines that crowd out sufficient space for larger aggregate and product to pass through.
The operation that I am a part of is proably rather simple compared to the processes that are conversed upon over this website. I would think however that characteristics within differring operations are generally the same - thus I offer this opinion. ■
Always Strive For Simplicity
In response to the excellent comments made by TOMINER..
Yes Yes Yes, there is no substitute for experience... hands on experience and keeping it simple.
Theory provides the backgound, experience the tools for the best result.
All the best for 2004 ■
New To Industry
Your web site is very interesting. I am just starting out and could use any information, tips, advice on the bulk bag cleaning business. Your site seems to be more technical but if you can steer me to other sites or contacts I would appreciate it.
Thanks,
George ■
Re: Welcome To "Ask Lyn Forum"
Wonderful observations by Tominer. He has so eloquently hit upon the one sorely overlooked facet of material handling, having the “practicle ability needed by plant and process operators to recognize alterations in material characteristics”. While the experienced operator is able to monitor complex process feedback and take corrective action, today’s reality is that process plants are subject to wage pressure, labor shortages and employee turnover. It is rare to have experienced operators available 24/7 for process coverage. Individuals whom “through experience or education have been familiarized with the characteristics of the materials” are indeed in short supply.
At the risk of sounding too much like an additorial, the objective of a well-designed process control system is to simply replicate the responsibilities of an experienced operator. The control system should instrument the same process variables used by the operator in his logical decision-making method. Process loading (amps) and dynamic (belt) weighing are a start, but with today’s sensor technology there is virtually no limit to the amount of data that can be collected. Computer technology is available to display in graphic detail the most inner workings of the process.
The trick to turning all this wonderful process instrumentation into a workable control system, is find a method for the control designer to download the cerebral matter of your plants most experienced operator. It is critical to find a controls supplier who actually understands process, not just programming, and link them into the experience base of your plant.
Unfortunately the controls are often looked upon as an afterthought. The process control system should be developed concurrently while the process is being defined, to ensure all the process objectives will be met.
Regards, Delmar Schmidt
Melfi Technologies Houston
Phone 281-298-8398
www.melfitechnologies.com ■
Welcome to "Ask Lyn Forum"
Bulk handling is a mature industry, after all goods have been stored and handled in quantity for thousands of years. However, the requirement of modern civilisation places much higher demands on the technology than in historical times. Great strides have been made in the theory of particulate solids to match this need, indeed it would appear that there is a satisfactory answer to any requirement in solids handling. The inescapable fact remains that plants handling bulk solids often encounter many operating problems and many fall far short of achieving optimum performance. This is not usually the result of any failure of the mechanical or chemical engineering but because the physical properties of the bulk material have not been properly accommodated by the installed equipment. How appropriate is the remark: - ‘We thought the plant was well made until we started commissioning’.
A 2- in foresight is worth a PhD in hindsight, but foresight requires a degree of experience to understand the potential difficulties that may arise. Some courage is also called for, to resist the pressures of time and cost that surround many projects and stick out for conducting due technical diligence in performance assessment. A flow audit that recognises the liabilities of non-performance will highlight the respective importance of key sections in the flow route, unrelated to their capital value that tends to influence the amount of attention directed to its design and selection.
Retrofit is another area that often operates under extreme pressure. Difficulties exposed at commissioning that delay production impose a high stress on all parties to secure a resolution. Unfortunately, skills lacking at the initial stage of a project may not be readily available later. Brute force solutions tend to be crude, expensive and not always very effective, sometimes leading to compromise situations. It does happen that intractable problems become accepted as inevitable and long running impediments to production or detractions from the product quality remain inherent to the operation.
Somewhere out there may be the answer to these awkward problems. The web has enormous scope for making contact with people of all disciplines and experience. Perhaps they have had similar problems and managed to find an answer or have the skill to suggest a practical or theoretical approach. Lyn Bates has been working in solids handling for many years and dealt with virtually all industries that handle bulk material. He is to host a column titled ‘Ask Lyn’, which is a platform for posing queries from users that are experiencing problems in solids storage and handling or looking for advise when contemplating a project.
Lyn Bates ■