Solids in a storage vessel tend to not settle evenly like liquids. High spots develop under filling points and low spots over emptying points, with peaks and valleys often forming less predictably throughout the vessel. This characteristic varies from product to product based on its stickiness and tendency to agglomerate, and it makes measuring the contents of solids stored in a vessel a challenge.
While there are reliable ways to take spot level readings, these often don’t present an accurate indication of overall level and can't provide accurate volumes, especially on larger vessels. In these cases, there's a need for measurements at multiple points to identify irregularities and produce an accurate picture of the peaks and valleys across the surface. This can be accomplished using the 3D measurement technology offered by Emerson’s Rosemount 5708 3D Solids Scanner, first released in 2014, and now updated to add new capabilities.
“Using its acoustic phased-array antenna technology, the 5708 measures multiple points on the material surface to create a very accurate topographical image of the product surface, and calculate a precise and continuous reading of the volume in the vessel. The acoustic waves have self-cleaning capabilities which prevent material from adhering to the internal workings of the antenna array,” says Lydia Miller, senior product engineer for level at Emerson Automation Solutions.
Emerson is now building on this success, adding two new licensed capabilities with to its Rosemount 3DVision software: Center of Gravity (COG) and Virtual Section.
COG: Most liquid storage tank level measurement instruments correctly assume the product weight distribution is relatively even, but this is rarely the case with solids. Depending on the severity of the concentration and the structure itself, there have been situations where vessels have tilted or even collapsed. This software feature allows users to define a COG zone in the software, and then automatically calculates the COG for the vessel’s contents with every reading. If the COG has moved out of its defined space, the software can generate an alert, so operations and maintenance teams can take appropriate action. The software displays X, Y and Z coordinates of the COG and the defined accepted area, so operators can see this characteristic continuously. The COG coordinates can also be read and monitored through a SCADA system.
Virtual section: The bigger the vessel or warehouse, the harder it is to control the material allocation and optimize filling and emptying processes. Many users end up resorting to manual surveys of the contents, putting employees at risk. Virtual section lets users divide a large vessel or warehouse interior to support continuous analysis of product flow and movement in a vessel. Properly controlled product movement can avoid dead spots where product tends to remain unmoved for extended periods of time. By creating virtual sections, each can be monitored individually, so if too much product is getting built up in one area, filling points can be switched. The virtual sections allow for even distribution and control of filling and emptying to maintain an even distribution across a large surface on a continuous basis, eliminating the need for manual surveys. Using Rosemount 3DVision software, product movement can be tracked and analyzed on a continuous basis. A vessel or warehouse interior can be divided into as many as 99 sections, each as small as 1.5 m x 1.5 m (5 ft. x 5 ft.), with minimum, maximum and average material level provided for each section.
“These capabilities can be added to Rosemount 5708S 3D Solids Scanners, which already offer a highly detailed analysis of a vessel’s contents. Many installations require only a single scanner, but the largest interiors may need multiple units to cover the entire surface,” adds Miller.
For more information, see www.emerson.com/en-us/catalog/rosemount-5708-solids-scanner.