I recently was able to speak in front of a group of 40 engineers representing some 1,000 years of experience in bulk solids material handling at the October meeting of the HMHS (Houston Material Handling Society).  This was truly a humbling experience for me ....... and one I took very seriously so I was not going to present a commercial.

A friend of mine recently wrote an Op-Ed for an automation magazine and in his editorial he said some things that I really identified with and I felt the HMHS engineers could benefit from so I started of the meeting with some quotes from Dr. Peter Martin's editorial in the September issue of InTech magazine where he stated that "engineers must step up and assume a leadership role within their companies by helping drive new levels of business performance". 

He further stated that the reason most companies don't understand the true benefit of the engineering discipline is that "most financial systems cannot measure the improvements" that engineers make.  I decided that my discussion about "recent directions in level monitoring and measurement of bulk solids" needed to provide these engineers some tidbits they could use to "add value" to their companies performance.

Want to know more? Click here for the rest of the story.

I was surfing around the other day and ran across the website of Spitzer & Boyes.  They are a consulting firm, they do training and write books and columns.  I spoke with David Spitzer, one of the authors, to see if he would be interested in guest authoring at the level measurement blog, but he gets paid to write and speak.  Any way, the book looks good but I haven't read it. 

The cost of the book is $250 and can be ordered from Amazon or click here.

Non-contact level sensors are a hot topic so this is why I thought you might be interested in this book.  However, contact level sensors (they are working on this book too) should never be ruled out and in fact I feel they are the best choice for most all applications. 

Open-air devices always have to deal with the internal vessel environment.  This especially true for powders.  I have found that the best technology available for continuous level measurement of powders is guided wave radar as this case history illustrates. 

And for granular plastics?  The leading technology is smart cable-based inventory monitors.  This is what ThomasNet can find on that subject.

Got an application you need to discuss?  Post a comment.  It's easy.

Joe Lewis

Flyash is a result of the combustion process that takes place in coal fired power plants.  This ash is collected and disposed of.  However, in recent years use of flyash has increased.  Cement producers and concrete manufacturing batch plants all use flyash to enhance the composition and value of the product they produce.

However, flyash is collected and stored in silos at the power plant, cement plant and concrete batch plant and the inventory of this material needs to be monitored for various reasons.  Flyash is lightweight, low in dielectric constant and extremely dusty, especially during silo filling operations.  These characteristics present challenges to nearly every form of level measurement technology.  This makes obtaining a consistent, accurate and reliable measurement very difficult.... until now.

A new "white paper" is available that discusses the nature of flyash, why it is difficult to measure and where it is used.  This paper then proceeds to offer a solution for measuring and monitoring the level and inventory of this increasingly used and valuable commodity and by-product of coal-fired power plants.

Click here for access to this free "white paper" entitled "Flyash Level Measurement Solutions".

If you have any questions or comments about this free "white paper", please let me know.  Thanks!

Joe Lewis
Vice President
Monitor Technologies LLC
jlewis@monitortech.com
www.flexar.info
www.monitortech.com

Finding the best level measurement solution for your bulk solids is not always simple and easy.  There are several different technologies to consider, including smart weight & cable, guided wave radar, ultrasonic, through-air radar and laser.  For the vast majority of bulk solids applications, especially for powders, the use of through-air technologies like ultrasonic, through-air radar and laser can be very problematic.  That leaves the smart weight & cable devices and guided wave radar as the most viable candidates.

When you need continuous measurement updates and prefer no moving parts, guided wave radar is your best choice.  Why?  Because, unlike most other technologies, radar technology is practically immune to process conditions such as temperature, pressure and atmospheric composition.  In addition, guided wave radar uses a continuous cable wave-guide to direct the radar pulses to the material surface.  The radar energy does not disperse, unlike through-air radar and ultrasonic.  This is important as only a small portion of microwaves will be reflected off the material surface.  The amount and strength of reflection is based on the dielectric constant of the target material.  The lower the dielectric constant, the less energy is reflected.  However, because the radar pulses are guided along the wave-guide stronger reflections exist than with through-air devices.  This is a major advantage of guided wave radar and is why it works!

Guided wave radar can effectively and reliably be used on challenging applications such as cement powder, flyash, slag powder and so many other bulk solid materials whether powder or granular.  And guided wave radar does not require high dielectric materials to work.  Guided wave radar, using TDR (time domain reflectometry) technology can measure materials with dielectrics as low as 1.4.

Need a solution?  Need a reliable and high-value level measurement system?  Look at today's guided wave radar units!

www.flexar.info

Joe Lewis
Monitor Technologies LLC
jlewis@monitortech.com
www.flexar.info
www.monitortech.com

In good times when there was plenty of grain, the ancient Egyptians stored their grain harvest in huge flat bottomed bins. As they drew the grain out, most of it would remain in the bottom of the bins (a typical funnel flow pattern developed whereby some material moved while the rest remained stationary). Essentially, the first material that entered the bin was the last to exit. 

In times of plenty, as grain was used it was replaced with fresh grain while the older grain remained stagnant.  However, during times of famine, the Egyptians would draw the grain out completely, thereby using the grain that had remained stagnant in the bottom of the bins.  Unbeknownst to them, as grain remains stagnant, it produces tetracycline, which as we now know is a powerful antibiotic.

Had the Egyptians known about mass flow (first-in-first-out), the grain would not have remained stagnant long enough to produce antibiotic.  Egypt's civilization, and those that followed, might have perished if the Egyptians had discovered how to insure a more efficient flow pattern from their bins.

Today, if you need tetracycline to fight an infection, you go to the doctor. And if you have flow issues where your product isn't moving reliably from your bins and feeders, you might want to consult a modern day flow doctor. In most cases, you'll find that the funnel flow pattern that serendipitously benefited the ancient Egyptians is a serious detriment in today's storage applications. Funnel flow leads to ratholing, flooding, segregation and many other flow issues.  Mass flow is typically required to overcome these flow issues. 

Joseph Marinelli
Solids Handling Technologies, Inc.
1631 Caille Ct.
Fort Mill, SC 29708
Ph:  803 802 5527
Email:  info@solidshandlingtech.com
Website:  www.solidshandlingtech.com

That's right.  According to a professor at Kansas State University and a representative of the U.S. Department of Agriculture, there was a total of 13 grain explosions reported in 2005.  This compared to only 6 in 2004.

Unfortunately these thirteen explosions had 2 deaths and 11 injuries associated with them.  They were spread around the country, with three in Minnesota alone.  Other states where these explosions occurred included North Carolina, Kentucky, Colorado, Iowa, Louisiana, Ohio, Oklahoma and Washington.

Causes of these explosions are still partly unknown, 5 out of 11.  Known sources include welding/cutting, extensions light, bearing failure and static electricity.

So, how do we prevent these catastrophic failures from occurring.  The loss of life is irreplaceable.  The cost of the damage runs over $500K in most instances.

Here's a link back to a couple of other related blog postings that provide more information about dust explosions and also about silo failures (an explosion qualifies).

Silo Failures and Dust Explosions (last post on this page)

Let's work together make 2006 much safer,
Joe Lewis
Vice President - Marketing & Sales
Monitor Technologies LLC
jlewis@monitortech.com
www.monitortech.com
www.flexar.info

When a silo fails it can be devastating, in more ways than one.  Loss of the vessel, contamination of the material it contains, loss of material, clean-up, replacement costs, AND possible injury or loss of life (the most important). 

Have you ever seen a silo fail, or that has failed (the aftermath)?  I recently surfed around the web and searched for images and documents that might tell me more about why silos fail and what can be done to make sure this doesn't happen.  I thought I'd post what I have found.

What I Did

After searching for images of silo failures and collapses I spent some time at the website of a company I feel is an expert in bulk solids storage, silo design and bulk solids flowability.  The company is Jenike & Johanson.  I discovered a wealth of information, some about silo failures and collapses, and I will review it with you here.

I reviewed "plastic-frictional theory" at the website for the Granular Volcano Group.  This was exciting (wink-wink).  But seriously, this highlighted a cause of silo failures specific to a certain class of material in specific industries.

I also uncovered a paper that discussed the failure of a grain storage facility in France.  This occured in 1997 and caused 11 deaths and 1 injury (twelve victims overall).  Let me start my summarization with this paper.

INERIS Report On Grain Elevator Silo Collapse

INERIS is a public research body employing 525 people with an annual budget of about 47 million Euro.  INERIS was founded in 1990, is an ISO-9001:2000 certified organization and has as its mission to "assess and prevent accidental and chronic risks to people and the environment originating from industrial activities, chemical substances and underground works".  A noble and worthwhile endeavor.

The report documents the sequence of events in the failure of this grain elevator.  The facility consisted of three rows of reinforced concrete silos, 44 in total.  The facility measured approximately 100m long, 20m wide and 40m high.  The capacity of the facility was 130,000 metric tonnes of grain.  The company owning the facility had 21 people to operate the facility, almost half were killed and injured during the catastrophe.  In fact, ten of the victims were found in the administrative/technical offices "at their workplace, apparently not having had the time to react to the incident".

The picture of the failed facility, figure 5 of the INERIS report, is quite graphic and indicates the failure of the entire center section of the facility with silo structures remaining to the right and left of the center.  The cause of the silo failure/collapse was an explosion, no big surprise for a grain elevator.  However, INERIS examined a tremendous amount of information and exhaustively studied the facility.  Their description of "The Explosion Sequence", section 3.2 on page 11 of the report is fairly detailed in how the explosion likely traveled and eventually resulted in the facility destruction and collapse.  They also conclude that "it is possible that the collapse of the structures was facilitated by structural weaknesses".  However, these possible structural weaknesses were not speculated upon.

The summary conclusion as to the cause of the explosion which resulted in the facility collapse is as follows:

"Following analysis of the various possibilities, and bearing in mind that no component parts of the centralised dust removal circuit were found, it appears plausible that the explosion arose either from mechanical impacts or friction in the fan of the centralised dust removal circuit, or from an incipient fire caused by self-heating in the dust chamber".

I found this report a facinating read and it reminds me of the dangers associated with the facilities handling powders and other bulk solids, especially grain elevators.  Careful design of the structure, proper equipment and maintenance are all critical to plant safety and silo integrity.

Why Silo Failures Happen - Jenike & Johanson Case Study

As a recognized industry expert in bulk solids storage and handling (Jenike, not me) I reviewed the information at the Jenike & Johanson website.  I uncovered a wealth of information on this subject, including newsletter stories, two white papers and a great case study that exemplifies the need for proper design, construction, inspection and use of silos containing powders and bulk solids.

The case study is an easy read and interesting.  This case study documents a silo failure that occurred in the southwestern USA in 1996.  The silo was a large 80ft diameter bolted steel vessel containing 9,000 tons of fly ash.  The only employee near the facility was very lucky as he recognized a warning sound just seconds before the silo collapsed and he hurried away, avoiding being buried under the 20 feet of flyash that covered the ground where he had previously been standing.

After studying the collapse it was concluded that several factors worked together to lead to the failure of the vessel.  These included a design issue and a manufacturing issue.  In addition, the infrequent discharge of the vessel may have precipitated the failure, when taken in conjunction with the other issues.  It is possible that had even just one of these issues not been present that the silo may not have failed. 

Click here for the case study.  It's number 2 on the list.  Also, I suggest you check out the papers titled "Load Development and Structural Considerations in Silo Design" and "Silo Failures: Case Histories and Lessons Learned".

I hope this trip down the "silo failure" lane has been interesting.  I do not work for either of the organizations mentioned, nor do I know anyone who does.  But their research and documentation helped me learn more about this problem, "silo failures - why do they happen".  I hope you enjoy the review.

Joe Lewis
Vice President - Marketing & Sales
jlewis@monitortech.com
Monitor Technologies LLC
www.monitortech.com
www.flexar.info