Performance analysis of 600 MW high sulfur coal unit desulfurization unit reform under ultra-low situation

The 600MW high-sulfur coal desulfurizers in a power plant in southwest China adopt the single-tower 5-layer spray limestone wet desulfurization process. However, the change in the quality of coals initiated the need for capacity expansion. A renovation by adding two layers of sprays brought significant improvement to the performances, with the SO2 concentration at the outlet remaining below 400mg/m3. In response to the government's call for ultra-low emission, the plant set up another renovation by constructing a new absorb tower, turning the 7-layer spray to an arrangement of 4+5 dual tower spray so as to lower the concentration of inlet SO2 from 12000mg/m3 to below 35mg/m3 through dual-tower desulfurization. The performance indexes of the two renovations were compared comprehensively, revealing that the gypsum is of poor quality and the content of fog drops at the outlet of desulfurizer is high. The paper also offers suggestions for optimized operation of desulfurizers.