Butterfly valve actuation system for ported kiln

The present invention relates to ported rotary kilns used, for example, in the reduction of iron ore, and more particularly to a butterfly valve actuation system for introducing air into the kiln at axially and circumferentially spaced locations along the kiln length. A method and apparatus for supplying air to a ported rotary kiln involves the use of butterfly valves and a mechanical valve actuation system for introducing air into the kiln at axially and circumferentially spaced locations along the kiln length. The valve actuation system selectively and sequentially opens and closes the butterfly valves such that port air is introduced into the interior of the rotary kiln. The valve actuation system of the present invention is incorporated with a butterfly valve having a valve housing with an air passageway and including an air inlet and an air outlet, a valve disc rotatable within the housing to open and close the passageway, and a valve stem defining an axis of rotation and connected to the valve member for rotation therewith. The valve actuation system includes an assembly mounted on the valve stem to rotate the valve member between its open and closed positions. The valve actuator assembly includes an actuator base connected to the valve stem for rotation therewith, a lever assembly mounted coaxially with the actuator base and valve stem to freely rotate relative to the actuator base and valve stem, and a lost motion mechanism interconnecting the actuator base and the lever assembly for transferring torque from the lever assembly to the actuator base as the lever assembly rotates.