Abstract: A method and improved furnace for reducing nitrogen oxide emissions from a furnace having a plurality of primary fuel injectors and a plurality of spaced apart over-fire air injectors positioned above the primary fuel injectors are disclosed. Injection of over-fire air produces zones of cooler combustion gasses containing over-fire air that separate zones of hot combustion gasses containing nitrogen oxides. Reburn fuel injectors inject a reburn fuel into the zones of hot combustion making the effluent combustion gases containing nitrogen oxides partially or totally fuel-rich in order to further reduce nitric oxide.

Abstract: A device for injecting dry material into a gas stream flowing through a duct or pipe has an injection tube having a first end configured for attachment to a dry sorbent supply, an upstream side and a downstream side. At least one opening on the downside side extends along the axial direction of the injection tube. A wake device is positioned adjacent the upstream side of the injection tube and creates turbulence in the gas stream as the gas stream passes around the wake device. An alternative embodiment utilizes an injector nozzle which combines a first stream containing dry material in air stream and a second stream which may be steam or water to form an output stream. A wake device is positioned adjacent the upstream side of the output of the injector nozzle. The wake device creates turbulence in the gas stream as the gas stream passes around the wake device.

Abstract: Methods for co-firing a fuel containing coal or oil that is injected into a burner in a furnace by injecting a gaseous fuel are disclosed. The gaseous fuel is injected in a manner so as not to consume air that would otherwise combine with the coal or oil in the primary flame. This can be accomplished by injecting the gaseous fuel at a higher or lower velocity than the coal or oil and combustion air are being injected. This can also be accomplished by directing the gaseous fuel being injected away from the primary flame created when the coal or oil burns.