Last year, Emerson’s Lydia Miller wrote an article for Powder & Bulk Solids titled Selecting the Right Technology to Measure Level and Volume of Solids. The article compared and contrasted GWR, non-contact radar and acoustic technologies for measuring the level of solids in vessels and silos. Lydia’s piece proved to be popular, so her colleague Andy Foust took up a challenge to create a follow-up article taking a deeper dive into one of those technologies.
In his new article in same magazine, Creating a Detailed and Accurate Picture of Solids Storage, Andy concentrates on the capabilities and advantages of acoustic transmitters using phased-array antennas, namely the Rosemount 5708 3D Solids Scanner. This approach is the only one capable of providing a detailed and precise picture of what is inside a vessel or piled on a warehouse floor. Just as a stereo camera uses two images to create a simulated 3D picture, the 5708 uses three sensors to build an image of the product terrain.
These instruments can perform sophisticated mapping of the product surface in a vessel. After sending sound pulses in different directions at three different frequencies, the antennas receive multiple echo signals from the walls and contents. Digital signal processing within the instrument samples and analyzes the echoed signals to produce accurate measurements of the level and volume across the entire surface within the wide beam angle of the device. Especially large storage environments may require more than one unit working together, but a single acoustic transmitter can cover a large area.
Other measuring methods, such as GWR or non-contact radar, can provide very accurate point readings, but only the 5708 can map the entire surface of the dry material and translate it into a precise value for the volume of product present.
For many applications, this kind of measurement is far more conclusive for purposes of inventory determination than any single point level reading. Yet as sophisticated as this technology is, there is more it can do. The same analytical platform capable of creating the 3D image of the material’s distribution can look more deeply into what’s happening inside the vessel.
So, this sophisticated measuring approach is only part of the picture. What are these other capabilities? One is the ability to determine when weight distribution is becoming problematic or even dangerous.
When product accumulates unevenly, the weight, naturally, is also unevenly distributed. Products that tend to bridge or stack concentrate weight as well as volume, which can cause problems and even vessel collapse in extreme situations. For products where this is a constant problem, most vessels will have some mechanism to break up the formations. The more problematic situation is where the product clumps intermittently, such as when humidity is excessively high. Operators may not realize when internal blockages are forming, and a filling or emptying cycle may trigger an incident.
Andy discusses how this kind of situation is particularly hazardous for elevated silos and those built of concrete. The solution is using the 5708’s ability to analyze the product’s weight distribution to determine where the center of gravity is within the vessel. If it is too far off the vessel’s center axis, an alerted is sent out.
The article goes into more detail about this capability and a new mechanism to monitor product movement within the vessel, so give it a full read. It also includes a case study of a plant using data from their 5708s to perform real-time inventory valuation calculations. The 5708 is a highly capable device and can solve many solids monitoring challenges. Andy’s article is online now and accessible at the link above, and it will be the cover story in the magazine’s December 2018 issue.
You can find more information like this, and meet with other people looking at the same kinds of situations in the Emerson Exchange365 community. It’s a place where you can communicate and exchange information with experts and peers in all sorts of industries around the world. Look for the Level Group and other specialty areas for suggestions and answers.