Combustion system with high turn down ratio

摘要

A low NO_x combustion system for reducing the production of nitrogen oxides in its emissions while allowing unusually high turndown ratios in operation is shown. The system includes an improved burner which has a firing head with an outlet end which can be mounted on a sidewall of a heat exchanger such as a boiler. The burner includes a fan, a windbox, a burner drawer assembly and a gas manifold. The windbox has an internal scroll-shaped passageway which is contoured to improve air flow from the fan to the firing head. An improved air straightener and diffuser head in the burner drawer assembly cooperate with improvements in the air supply system to provide improved combustion characteristics and a higher than usual turndown ratio for the burner assembly.