The Postheater/Dryer/Mixer’s heating system is the same as in the Preheater and Preheater/Miller. It combines high-velocity forced hot air with low-level infrared heat. The system incorporates a diesel fuel burner, combustion air turbo blower, recirculating hot-air blower and a stainless-steel heating plenum. The burner heats a large amount of air in the heat-insulated, stainless steel combustion chamber. The hot air is forced into the heating tubes located in the insulated heating plenum. On the bottom of the heating tubes there are thousands of small holes through which the high-velocity hot air is blown onto the road surface. Since most of the oxygen from the fresh air is used for combustion, the hot air used for heating has low oxygen content, avoiding oxidation of asphalt binder.
Hot air is then vacuumed by the road surface by the circulating hot-air blower and blown back into the combustion chamber to be reheated. About 10% of the air is exhausted to make room for fresh air needed for combustion, which is supplied by the combustion air turbo blower. Four lifting and two tilting cylinders are used to adjust the heating plenum.
A fully computerized flame-management system, combined with an advanced fuel-control system, ensures the reliability of the combustion-chamber flame for safe and continuous operation. The operator can monitor and control the temperature of hot air from the operating station.
The combination of economic diesel fuel with the hot-air heating system provides a major advantage over other hot in-place recycling equipment: the AR2000 offers significant cost savings, a safer environment for operators, and conservation of energy and natural resources. Under normal operating conditions, the system is virtually emission-free.