(RED) RAP Ecological Dryer
The latest development from Bernardi Impianti SpA
Italian manufacturers Bernardi Impianti SpA, who have been building asphalt plants for more than 50 years and have in excess of 1,000 plants installed around the world, have developed the innovative RAP recycling system known as the (RED) Rap Ecological Dryer, which claims to be able to dry up to 50% RAP without the problematic blinding, steam, screening and emissions issues normally associated with processing RAP.
The RED dryer accepts recycled asphalt planings or plant-generated waste fed from the existing cold-feed system and directly blended with the primary aggregates; no secondary RAP equipment is required. A specially designed blading system inside the dryer retains the blend of aggregate and RAP against the outside of the drum, thus avoiding any direct contact with the flame and eliminating any thermic shock to the bitumen.
The RED dryer uses the heat radiated from a patented stainless steel combustor within the drum to heat the materials, while the special blading system transports the primary aggregate and RAP through the dryer. This system also incorporates a special blending process which ensures that any ‘free’ binder from the RAP is absorbed by the dust in the virgin aggregate. This process produces a blend of virgin aggregate and RAP that is dry enough to screen without the normal blinding and moisture issues.
The combustor is heated by a Bernardi inverter-assisted burner which creates a vortex of air around the combustor to optimize the efficiency of the combustion process. The air flow around the combustor also draws in all harmful combustable gases produced by reheating the RAP and reprocesses them through the combustor, completely eliminating the harmful emissions normally produced when heating such material.
Since its launch in January 2009 Bernardi Impianti have installed in excess of 20 units in Italy and have more than 20 orders placed in the factory. Indeed, Bernardi are so confident of their product that they have endorsed the RED system by offering guaranteed production and emission levels and providing a two-year warranty.
Bernardi’s UK agents, Berkshire Engineering Supplies Ltd, have taken many of the UK’s leading asphalt manufacturers to Italy to view the RED dryer in operation and are now in the process of looking at a number of applications throughout the UK where the RED dryer could potentially be installed.
The UK Highways Agency currently allows the use of up to 50% asphalt planings in road basecourses and 10% in surface courses. As the RED dryer allows asphalt producers to screen the RAP, the potential for using a larger proportion of recycled asphalt in asphalt mixes is significantly increased.
Every year, nearly 20 million tonnes of planings are removed from the UK’s roads, but currently only a small fraction is ever reused. At present, less than 2–3% of recycled asphalt is recycled back into UK roads, while Europe and the US use, on average, around 25% recycled asphalt in all types of asphalt courses.
The RED dryer’s innovative technology allows RAP to be considered as a valuable resource rather than a waste product. The reuse of RAP will significantly reduce the carbon footprint of the road-building industry, making the RED dryer an environmentally efficient and cost-effective solution for asphalt production.