At WWA Westerwald Asphalt, reductions to TC emissions of more than 50% are now possible – thanks to the new REVOC system.
As part of a pilot project, the innovative REVOC system from Benninghoven was installed for the existing asphalt mixing plant at WWA Westerwald Asphalt GmbH & Co. KG in Nentershausen, Germany. Following its official world premiere at bauma 2022, this “catalytic converter for asphalt mixing plants” is now demonstrating its strengths in the real world – and exceeding customer expectations.
The Benninghoven type TBA plant, manufactured in 2007, is located on a basalt quarry site and produces 80,000 to 100,000 t of high-quality asphaltic mixture for road/roadway construction every year. Benninghoven and WWA Westerwald Asphalt have a good, well-established working relationship. For this reason, they were happy to play a pioneering role in the industry by retrofitting the REVOC system in 2021.
“We chose the REVOC system because it allows us to reliably comply with the TC emissions even with high rates of recycled material usage.”
Peter Bach, CEO WWA Westerwald Asphalt
Thanks to this patented, pioneering technology, Westerwald Asphalt is now in a position where it can increase its maximum recycling feed rates from an earlier 30–40% to 50%, while simultaneously reducing its total carbon (TC) emissions by more than 50%. In an interview, CEO Peter Bach reports on initial experiences with using the new system, and how the REVOC installation helps to secure the future of the plant and the site.
There are two key factors for sustainable asphalt production. On the one hand, recycling feed rates need to be increased: this conserves resources and makes good use of reclaimed material. As the proportion of reclaimed asphalt added rises, less fresh bitumen is needed, which works to shrink the carbon footprint. On the other hand, strict TC limit values need to be observed in Germany, with “TA-Luft” requiring <50 mg/m³ to be met in accordance with climate legislation.
Previously, reclaimed asphalt has been easily incorporated into the production process by utilizing cold or hot recycling techniques. However, this approach results in higher emissions of total carbon (TC) in the form of VOCs (volatile organic compounds). This is because heating reclaimed asphalt causes some of the TC present to evaporate out of the bitumen contained in the asphalt. These VOCs are more potent greenhouse gases than CO₂ and are also hazardous to health at higher concentrations.
In the past, trying to reconcile high recycling rates for reclaimed asphalt with the need to avoid environmental impacts was effectively impossible. Thanks to the powerful REVOC system, the two aspects can now be consolidated: reducing TC emissions by up to 50% and implementing higher recycling rates of up to 60%.
REVOC – cost-effective and environmentally compatible
The system works like a catalytic converter. The vapors created by the mixer in the asphalt plant are extracted at their place of generation and routed for thermal treatment to the downstream REVOC system. This is where TC emissions can be reduced by up to 50%. This makes it possible for the plant operator to ramp up their recycling feed rates without risking a situation where limit values are exceeded. At the same time, the reduced proportion of primary raw materials used conserves resources and cuts costs. Alongside these economic and ecological aspects, the use of the REVOC system is an investment in the future of the plant – also in light of a potential tightening of emissions regulations going forward.
One year after initial talks began, the REVOC system was installed in the plant at WWA and adapted to customer requirements. From the outset, a full aftersales service was provided – on site, by phone, or via remote management. A key aspect of this was routine measurement of emissions figures, which was used as input for fine-tuning of the plant. The end results significantly exceeded the expected reduction in emissions of 50% and has been repeatedly confirmed by external measurements. “Even if the upper limits for plant emissions are further reduced, we’re easily in the clear here,” explains Peter Bach, CEO of WWA Westerwald Asphalt.
“We’re very happy with the system.”
Peter Bach, CEO WWA Westerwald Asphalt
