Experimental Study on Peak Shaving Operations for Efficient Pulverized Coal Combustion and Working Fluid Coordination

Abstract

Ensuring stable combustion and responsive load regulation in coal-fired power plants is essential for maintaining grid stability as renewable energy integration continues to expand. This study investigates the stable operation and dynamic response characteristics of coal-fired boilers across a broad load range using pulverized coal fluidized preheating combustion technology. A novel stability criterion based on steam parameters on the working fluid side is proposed to enhance load response accuracy and improve operational stability. Its response characteristics were compared with the combustion-side temperature criterion during load variation scenarios. Experimental results showed that fluidized preheating combustion achieved stable combustion at 25% ultra-low load. The carbon lattice defect rate increased by 45%~68%, promoting fuel reactivity and efficient combustion. NOx emissions remained below 300 mg/m³ (@6% O2), representing a 35%~40% reduction compared to conventional combustion methods. Dynamic analysis based on steam parameters indicated that the load ramp-up rate (2.21%~3.13%/min) exceeded the ramp-down rate (1.55%~2.30%/min), with both rates improving as the load change range expanded. Compared to the combustion temperature criterion, the steam parameter criterion improved the load ramp-up rate by 24% and the ramp-down rate by 29%. This improvement highlights the superior sensitivity of the steam parameter criterion to heat transfer dynamics on the working fluid side. Based on these findings, a combined stability criterion integrating combustion temperature and steam parameters is proposed to further enhance variable load rates. This study provides fundamental data and theoretical insights to improve the flexible peak shaving capability, and clean, efficient operation of coal-fired power plants.

Keywords: Flexible peak shaving；Self-preheating combustion；Variable load rate；Steam parameters