Multiple-shutter throttle characterization assembly for burners

Abstract

The present invention provides an air box throttle assembly for improved characterization of a combustion system in which an arrangement of three air shutters is used to maintain a fairly constant air to fuel ratio as the combustion system is driven from low fire to high fire. A high fire shutter and a main air shutter each comprise two vanes and are rotatably mounted within an air intake box for a combustion system. A low fire shutter is provided with a single vane and is fixed above the main air shutter. The high fire shutter is the principal regulator of large volumes of air entering the combustion system when operating at high fire. At high fire, the main air shutter is fully open and low fire shutter has little effect on the flow of air through the air intake box. Low fire shutter is the principal regulator of small volumes of air entering the combustion system when operating at low fire. At low fire, the main air shutter is substantially perpendicular to air flowing into the air intake box such that air flow is forced through a passageway defined between the low fire shutter and the main air shutter. When the combustion system is operating in the range between low fire and high fire, the high fire shutter is substantially open and the main air shutter is used to regulate the volume of air flowing into the combustion system.