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: Methods and systems for measuring a gas flow rate and/or a solids feed rate by detecting a vibroacoustic emission caused by passage of the gases and/or solids through an interior of a pipe are described. The methods include correlating an intensity of a broad-band vibroacoustic emission having a frequency of up to 3,200 Hz with a change in the gas flow rate. The methods also include correlating a change in a position of a narrow-band vibroacoustic emission having a frequency of up to 800 Hz with a change in the solids feed rate. The methods further include correlating the change in the position of the narrow-band vibroacoustic emission with an absolute solids feed rate. The systems include at least one vibroacoustic sensor and at least one computer program product having machine-readable instructions executable on at least one processor for performing the described steps of correlating.

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.