Research on operational characteristics of a supercritical W-shaped flame boiler under ultra-low load based on Operational data diagnosis

Abstract This study focuses on a 660 MW supercritical W-shaped flame boiler. Utilizing real-time DCS data and field tests, a comprehensive diagnosis was conducted on its operational characteristics at 35% and 25% (with oil-support combustion) rated loads. The research results show that oil-assisted combustion reduced the amplitude of furnace pressure fluctuations by 39.6%, significantly enhancing combustion stability; however, it also caused a marked decline in both the economic and environmental performance of boiler operation. In terms of economics, a sharp increase in exhaust gas heat loss was the primary cause of the efficiency drop. At 25% load, boiler efficiency decreased to 88.04%, an absolute reduction of over 4 percentage points from the design value. Simultaneously, the attemperation water ratio surged to 4.70%, resulting in substantial energy waste. Regarding environmental performance, a “pollution transfer” phenomenon was observed. SO 2 emissions decreased by over 60%; however, the concentration of particulate matter (PM) emissions doubled, and NOx emissions remained high, indicating a heavy reliance on end-of-pipe treatment.