BigPatents India

A method and apparatus for introducing solid, liquid or gaseous fuel into a burning zone of a rotary kiln for manufacturing cement clinker. Fuel is conducted through a duct or ducts and primary air is conducted through at least two annular ducts arranged concentrically with, and around, the fuel duct(s), the portion of air in one of the air ducts flowing axially, whereas the portion of air in the second of the air ducts comprises air which has a rotary component about the center axis of the burner, and wherein the amount of primary air in the two portions is independently controlled, such that the two portions of primary air are mixed at a lower velocity in a collecting duct into a single primary mixed airstream having a desired axial/rotary flow characteristic, and wherein this airstream is subsequently accelerated up to a desired, higher discharge velocity.