Abstract: A method of controlling operation of a particulate fuel burning boiler, such as a coal fired boiler, having a plurality of burners each receiving pulverized coal, primary air and secondary air. The flow rate of the pulverized coal, primary air and secondary air is determined independently for each burner and is compared with a model. In the event that the comparison results in a determination that one or more of the flow rates depart from the desired rate by a predetermined amount, a control signal is emitted to adjust the air to flow ratio entering the specific burner. The control signal which alters the air to fuel ratio may result in alteration of the air or fuel flow rates. The method may be employed to reduce NOx emissions, loss on ignition and to optimize heat rate.

Abstract: A method of repairing a defective portion of a tube which is one of a plurality of generally parallel elongated tubes includes severing an axial portion of the tube which contains a defective portion, bending the free end portions of the tube disposed adjacent to where the axial portion which was severed, and securing an insert tube to the free end portions of the tube disposed adjacent to where the removed axial portion was located to thereby establish a passage for free flow of fluid within the repaired tube. In a preferred embodiment of the invention, the free end portions will be bent in substantially the same direction about 20 to 60 degrees with respect to the longitudinal axis of the tube when the tube being repaired is part of a water wall of a fossil fuel fired boiler and the repair is effected from the cold side thereof.