[Objective] Co-firing of biomass and coal is a pivotal technology for the low -carbon transformation of coal-fired power plants, as biomass is a carbon -neutral renewable energy source with abundant reserves that can 2 effectively reduce carbon emissions from power generation. However, biomass fuels generally contain high concentrations of alkali metal elements, especially potassium. During combustion, these alkali metals are released into the gas phase in large quantities, condense, deposit and sinter on the s urface of boiler convection heating surfaces, causing severe fouling and slagging problems. This reduces the heat transfer efficiency of heating surfaces, increases boiler exhaust heat loss and power generation coal consumption. The traditional offline evaluation method of heating surface scaling has a large lag and cannot meet the actual requirements of real -time monitoring and precise prevention and control of industrial sites. Therefore, it is importance to realize the dynamic evaluation and prediction of the fouling characteristics of heating surfaces during the combustion of coal and biomass blended fuels. 

[Methods] In this study, the designed relevant experimental tests were carried out on a 5MW pilot furnace. Optical detection equipment was used to collect real-time data, including flame temperature and gaseous potassium concentration. They were applied to dynamically evaluate the fouling trend of heating surfaces during coal-biomass coupled combustion . the evaluation results were verified by combining the changes in the heat effectiveness coefficient and the actual observed fouling status on the surface of the fouling tubes. 

[Results] The experimental results showed that for every 1% increase in the furnace outlet oxygen concentration, the flame temper ature and gaseous potassium concentration increased by approximately 22.5℃ and 2.0 mg/m³. When the blending ratio of corn stover increased from 0% to 100%, the gaseous potassium concentration reached a maximum of 15.71 mg/m³, respectively. The heat transfer effectiveness coefficient decreased from 0.9 to around 0.5, and the surface fouling degree of the fouled tube significantly intensified. There is a significant correlation between the increase amplitude of gaseous potassium concentration and the attenuation amplitude of the heat effectiveness coefficient. 

[Conclusion] The established dynamic fouling assessment method based on in -situ measurements of flame temperature and gaseous potassium presents favorable prediction accuracy. The obtained experimental f indings can provide fundamental theoretical guidance and database for developing anti-fouling technologies and optimizing operational parameters for high alkali fuel combustion. Eliminating the inherent delay of traditional off -line detection techniques, t his method possesses promising application prospects for on -line fouling monitoring of industrial boilers.