| 摘要 |
An inclined counterflow rotating drum mixer has a burner head (22) intermediate an aggregate inlet (14) at one end of the drum and an asphaltic concrete discharge (18) at the opposite end of the drum (12). A fan supplies secondary air to the burner (22) through a motive tube having an opening in communication with a mixing chamber (26) between the burner head (22) and the discharge end of the drum (12) to aspirate gases from the mixing chamber (26) for flow through the burner flame. The aspiration creates a negative pressure in the mixing chamber (26) , causing a reverse flow of a portion of the combustion gases from the dryer chamber (24) into the mixing chamber (26) for preheating RAP input to the mixing chamber (26). RAP is also preheated by providing a preheat chamber (50) adjacent the flame zone but segregated from direct contact with the flame to preheat the RAP. Hot and dried virgin aggregate is mixed with the RAP in the preheat chamber (50) and valves (66) are provided to prevent gases evolved from the RAP in the preheat chamber (50) from flowing into the drying chamber (24). <IMAGE> |
