Study on On-line Monitoring method for Local Slagging in the Coal-Fired Boiler Furnace

Abstract Slag formation in coal-fired boiler furnaces is an unavoidable issue, which is further exacerbated by the combustion of Zhundong coal. The accumulation of slag in the furnace can reduce the heat exchange capacity of the boiler, leading to a decrease in power generation efficiency and operational economy. However, there is currently a dearth of monitoring techniques to evaluate the local slagging status in the furnace. To address this gap, this study proposes an innovative approach by installing multiple thermocouples on water wall tubes and fins to establish an online monitoring model for local slagging based on temperature differences. The effectiveness of this model has been validated on a 660 MWe utility boiler. The monitoring results reveal that the slagging in the furnace is uneven and asymmetrical in both the circumferential and longitudinal directions. The central region of the water wall in the circumferential direction is particularly prone to slagging, and the main combustion zone exhibits the highest slagging rate, while the burnout zone experiences the lowest. Moreover, the slagging rate in various regions is influenced by the unit load. It is directly proportional to the load in the main combustion zone, inversely proportional in the furnace bottom zone, and relatively unaffected by the load in the burnout zone.