Method and apparatus for recovering energy from waste materials by combustion using a portion of tertiary air

An apparatus for recovering energy from waste materials by combustion using hot tertiary air for using in rotary kilns having a calciner and a tertiary air duct comprising:

• one or more combustion chambers formed into the calciner tertiary air feeding duct, each having water cooled releasable retaining means therein for retaining the waste material inside the combustion chamber until a complete combustion is achieved by using a fraction of tertiary air, said water cooled releasable retaining means allowing the flow of combustion gas and air through itself;
• one or more feeding means each connected to a combustion chamber for feeding waste material to the combustion chamber further avoiding the loss of heat or the entrance of cool air from the exterior into the combustion chambers through the feeding means;
• and
• wherein the combustion chamber delivers hot combustion gas to the calciner for its use as supplemental energy source by the rotary kiln and remaining material in order to be incorporated to the cement clinker.