IMPROVED APPARATUS AND METHOD OF OPERATION FOR BURNERS THAT USE FLUE GAS RECIRCULATION (FGR)

摘要

The present invention is a method and apparatus to improve the utilization of flow and power characteristics of a combustion air fan over the full range of burner operation. More specifically, it is an apparatus and a method of operation that uses a high flue-gas-to-air ratio over most of the boiler operating range to maximize thermal efficiency, but which switches to a lower ratio of flue-gas-to-air, or no flue gas in the limiting case, at the high end of the mass flow range of the burner to minimize the size of the fan housing and fan motor. When applied to current generation ULNBs, fan size can be reduced about 50% and operating power consumption can be reduced by about 50% without adversely affecting NOX emissions.