Top Tower 3000 – “Les Enrobés des Trois Frontières”
Increasingly strict regulations regarding both plant pollution and energy consumption together with cost-efficient asphalt production have led “Les Enrobés des Trois Frontières” to replace their MARINI M220 plant, in operation since 1990 on the Aubange site in Avenue de Champion 24, with the most contemporary alternative – the Marini Top Tower 3000.
The strategic position of the site means that clients from Belgium, France and Luxemburg are all within easy reach. Therefore, with a wide customer demand as regards both the type of formula and the type of production depending on the country of the end-user, Les Enrobés des Trois Frontières decided to chose a plant designed to work with the most up-to-date asphalt technologies and a high percentage of RAP. Les Enrobés des Trois Frontières showed immediate interest in Marini’s proposal for the use of RAP through the ‘double line’ feed system (cold RAP into the mixer + RAP into dryer drum), which then resulted in their final choice. In fact, at the moment Marini’s solution is unique, with the percentage of RAP reaching levels almost as high as with a parallel drum (in many cases plants are utilizing as much as 50%!!!), and with remarkable advantages in terms of both initial investment and maintenance costs plus operational flexibility.
MARINI TOP TOWER 3000
A singular characteristic of the plant is the dryer-filter-recovered fines unit. At the client’s specific request to maintain the dryer drum of the old Marini plant (installed in 2007), the Top Tower solution with dryer and filter tower (i.e. with filter and recovered fines hopper stacked above the dryer drum) was not adopted. The plant parts supplied to Les Enrobés des Trois Frontières, to supplement the E250L/R dryer unit from the original plant, were a ground-mounted filter (875 sq.m.) and ground-mounted recovered fines hopper (52 sq.m.) together with the MARINI TOP TOWER 3000 mixing tower. Correct bag filter functions, when working with warm asphalt mixes, are guaranteed by an auxiliary burner installed on the connection of the fumes duct between the dryer and the filter. The burner heats the gases when entering the filter to avoid condensation forming on the bags, while at the same time taking maximum advantage of the efficiency of aggregate dehumidification in the dryer. The plant is equipped with 8 aggregate cold feeders, 2 RAP feeders (one for feeding into the dryer drum through the recycling ring and one for feeding cold RAP into the mixer), 6-selection screen and 200 ton hot asphalt storage with four compartments. Binder storage consists of 3 electrically-heated tanks, with 200 mm thermal insulation to reduce heat loss and consequent electric energy consumption to a minimum, plus complete insulation of the bitumen piping, which is heated electrically through a self-limit cable – a solution which has helped to stop the bitumen cracking in the pipes. This Marini plant has become a term of reference, above all for clients in Northern Europe with traditionally high standards and concerned with high product quality, energy savings, the environmental footprint and cost-efficiency of production. Furthermore, as regards the use of high percentages of RAP, Marini has demonstrated that with this plant it is able to supply its customers with a valid alternative to the parallel drum, which was previously regarded as the only valid solution for the Northern market, particularly in Belgium.