Experimental Study on the Flexible Peak Shaving with Pulverized Coal Self-Preheating Technology Under Load Variability

Abstract

The integration of renewable energy sources into the power grid has led to power fluctuations, necessitating coal-fired units to provide flexible peak shaving. The pulverized coal self-preheating technology holds the potential to provide broad-load regulation and rapid response to load changes. This study investigated the impact of self-preheating technology on fuel preheating modification, combustion characteristics, and NOx emissions. The load-stabilization bases are proposed based on preheating temperature, preheated coal gas, combustion temperature, and flue gas emissions. Load change rates are calculated  to assess the load response characteristics. The results demonstrate that the preheated fuel has similar properties to highly reactive gaseous fuel and exhibits excellent ignition and combustion performance. Preheating treatment improves combustion efficiency, and burnout ratio and reduces NOx emissions. The NOx concentration approaches the ultra-low emission standard at 50% load. Four load-stabilization bases, covering the preheating and combustion sides, comprehensively characterize the load response performance. The rate based on preheating indicators attains the highest value of 3.30%/minute, while the rate based on combustion indicators peaks at 2.71%/minute. The load change rate in the ramp-up phase is higher than that in the ramp-down phase, which is related to the effective internal heat storage carrier and external thermal insulation conditions.

Keywords: coal combustion, peak shaving, Self-preheating, Load-stabilization basis, Load change rate