Research on the deterioration mechanism and cleaning effect evaluation of organic heat carrier boilers

This study conducted a large-scale investigation of 440 boilers across six regions in China to systematically analyze the degradation mechanisms and cleaning inspection methods for organic heat carrier boilers. The findings reveal that the degradation rate of the oil in open systems is significantly higher, with carbon residue values exceeding 1.5 % within four years, whereas closed systems can maintain stable oil quality for over five years. Proper cleaning and oil replacement can reduce fuel consumption by more than 20 %. A series of simulated cleaning experiments were conducted using various agents, to evaluate their effectiveness. Revealing that the combination of organic and inorganic cleaning agents achieved the best cleaning performance, with a decontamination rate of up to 92 %. However, online cleaning agents tended to accelerate oil degradation above 250 °C, limiting their effectiveness. Infrared thermal imaging technology was employed to analyze the temperature distribution of boiler tube walls before and after cleaning, as well as the quality changes of newly replaced organic heat carriers. Infrared thermal imaging inspection of heat exchanger indicated that the surface temperature of severe carbon accumulation areas decreased by 30–60 °C, confirming that this technology can serve as a reliable diagnostic tool.