Experimental study on the effects of reheat temperatures on the ammonium bisulfate and ash blend deposition

Ammonium bisulfate (ABS) and ash blend deposition blocks and corrodes air preheaters in coal-fired power plants, seriously affecting the safe operation of the boiler, especially when the selective catalytic reduction (SCR) system is widely used. In this work, a self-reheating probe was used to investigate the effects of reheat temperatures on ash deposition cleaning. The results showed that reheating could significantly reduce the ash deposition. When the reheat temperature exceeded 365 degrees C, the metal surface of the probe could be clearly seen. After ash deposition, the stable relative heat flux was about 0.881, and it increased significantly after reheating. For cases 4 (365 degrees C), 5 (385 degrees C) and 6 (430 degrees C), the relative heat flux after reheating was 0.986, 0.997 and 0.997, respectively. Microstructure results showed that the phenomenon of particle agglomeration was obviously reduced after reheating. X-ray diffraction (XRD) and thermal gravimetric analyzer (TGA) results indicated that the contents of ABS and Ammonium sulfate (AS) were significantly reduced in case 4, and they hardly existed in cases 5 and 6. This work provides a new method for cleaning ash deposition, which has a guiding role in the safe operation of the air preheater.

Automated summary

This study investigated the effects of reheat temperatures on ash deposition cleaning using a self-reheating probe and found that reheating could significantly reduce ash deposition. It provides a new method for cleaning ash deposition and has a guiding role in the safe operation of air preheaters.