99/00580 Application of RBC burners in 220 t/h boilers in Xinhua power plant

Abstract

The Radial Bias Combustion (RBC) pulverized coal burner was developed to simultaneously solve five problems, i.e. combustion efficiency, flame stability, slagging, high temperature corrosion of furnace wall tube metal and NOx emission, that existed in firing low grade Chinese coal. It was developed for wall fired systems. A RBC burner is usually facilitated in the following way: A fuel enricher of high enriching ratio is installed in the fuel transport channel which separates radially the fuel air stream into two streams of proper fuel concentration. The fuel-rich stream injects through the fuel nozzles, forming a high temperature annular core just outside the recirculation zone in the center of the flame; the fuel-lean stream injects through the fuel lean nozzles outside fuel rich flame and blanketing high temperature flame core with an out layer of more oxidizing atmosphere. RBC burners have been applied to the retrofit of coal burners of No.1 and No.2 boilers in the Xinhua Power Plant. These boilers are high pressure ones of 220 t/h rated steam capacity which were retrofitted from oil fired boilers. Prior to the retrofit with RBC burners, flame stability was very poor. It needed auxiliary fuel oil to enhance its stability at 70--80%more » rated capacity. NOx emissions did not meet environmental regulations. Satisfactory results have been obtained after the retrofit. Flame stability has been improved a great deal. The minimum load without auxiliary fuel has reached 40%. Furthermore, RBC burners raised the combustion efficiency. Lastly, NOx emission have been abated and meet Chinese legislation.« less