Research On Combustion System Reformation Of300MW Utility Tangentially-fired Boiler

The operation Safety of thermal power generation unit is an important issue to China’s power industry and even to the national economy. Some problems existed in a300MW subcritical boiler such as high carbon content in ash, low reheat steam temperature, steam temperature offset at the outlet of the furnace, combustion instability and so on. In response to these problems, the author analyzed the furnace structure of the300MW subcritical boiler and layout features of the burner, and discussed causes of the boiler operation problems systematically with the combination of combustion theory in pulverized coal boilers. Correspondingly, the author raised a series of reformation projects of the furnace and the burners such as nozzle exchanges, tertiary air declination and so on to solve the problems, and discussed the effect of the reformation projects on boiler operation. Based on FLUENT numerical simulation platform, a numerical simulation is performed. The numerical simulation is about gas-solid flow in furnace and combustion process after the implement of reformation projects including nozzle exchanges and refractory belts addition and so on. The simulation can provide a reference to site operations. According to above reformation projects, certain components were machined and the improvement of combustion system was performed during the overhaul project of the boiler, which includes nozzle exchanges and refractory belts addition. The reformation implemented tertiary air declination and horizontal swing of OFA nozzles and become a flexible adjustment method of the boiler’s combustion system. After the reformation, a combustion adjustment test of steam temperature, carbon content of bottom ash and thermal deviation were performed. And a stable-combustion test in under load also be performed. The results of the tests indicated the original problems of the boiler were improved a lot after the reformation.