Many countries in Europe have rapid growth in Energy from Waste plants as a means of turning municipal waste into green energy. This process produces a small amount of residue from the flue gas treatment (APCr) that has historically landed in … landfills.
But for Carbon8 Aggregates Ltd. (Carbon8), they dared to be different as pioneered a truly green alternative. The company uses a patented process known as Accelerated Carbonation
Technology to transform the APCr into a product called C8Agg.
This is a carbon negative aggregate that has many uses including in the manufacture of dense and medium-dense masonry blocks.
Tens of thousands of tons of C8Agg is produced annually at two Carbon8 plants in the UK. Each site has numerous silos for reception and storage of the incoming residue. The site at Avonmouth, for example, has eight 130 cubic meter silos receiving between 7-8 tanker loads of APCr per day.
The recipe for C8Agg requires the treatment of a precise mixture of APCr's from multiple sources which vary widely in density. To ensure this precise mixture, Carbon8 needed to a way to measure their inventory levels with a high degree of reliability & accuracy.
Unfortunately, receiving accurate measurements turned out to be easier said than done with the technology The grades of APCr not only vary in density but also have a very low dielectric constant, making the material hard to detect with conventional-level solutions, Carbon8 engineers considered multiple options including silo weighing, but this was discounted because of the density variations meaning the weight is not a direct representation of the capacity of the silo.
Accurate detection for even the most difficult substances
Fortunately, Carbon8 ultimately turned to Underwoods as their trusted technical partner and our process instrumentation experts specified a high-frequency SITRANS LR560 radar level transmitter for solids which was installed in each C8Agg silo.
The SITRANS LR560's narrow four-degree beak immediately proved that it could deliver consistently accurate, repeatable and reliable measurements of the vexing low-density APCr without any recalibration.
Measuring made easy
Since device programming & set-up was made slightly trickier due to the mounting location within the silo, the cross-vendor SIMATIC Process Device Manager (PDM) from Siemens was an enormous help as it enabled all device configuration tasks to be done remotely, so there was no need for manual intervention after the devices were fixed into place. Once a calibration had been established for one silo, it was seamlessly replicated in all other silos with just a few keystrokes.
With their reliable measurement package in place, staff at Carbon8 can now view the impeccably precise level readings they need right on their control system's monitor. The technology is hassle-free without the need for manual intervention as maintenance, cleaning and upkeep are kept to an absolute minimum.
Levelling Up Carbon8’s Measurement Expectations
" It was vitally important that we have a reliable level measure", says Tom Bissett, National Engineer and Projects Manager for Carbon8 Aggregates Ltd, admitting that after all the technological problems he and his team had encountered, he was initially sceptical that Underwoods and Siemens could deliver, only to end up with a very pleasant surprise.
"The SITRANS LR560 solved a problem we thought could not be achieved within our budget. Siemens and Underwoods worked closely together through the initial presentation, feasibility, trial, extended plant trial and final installation and commissioning phases of the project. I am completely satisfied with the results of their combined efforts. Other manufacturers and distributors did not have the confidence to offer a no obligation trial.”
“We will spread the word in the energy-from-waste world if we hear of any of our customers and partners having similar difficulties to what we had before partnering with Underwoods." Tom Bissett - National Engineer and Projects Manager: Carbon8 Aggregates.