An Effective Strategy for Monitoring Slagging Location and Severity on the Waterwall Surface in Operation Coal-Fired Boilers

Abstract

It is of great importance to obtain the exact location and severity of slagging deposits on the waterwall surface of an operational boiler to avoid aimless soot-blowing and reduce steam consumption. In this paper, an effective waterwall surface temperature monitoring method is proposed to determine the slagging locations. It has been noted that the temperature difference of the waterwall surface before and after soot-blowing varied with the waterwall location, with more than 80 °C covered with slag and less than 20 °C found clean. According to this, a slagging temperature index was developed to describe the severity of slagging deposits on the waterwall surface. Results indicated that the process of slagging deposit growth included four stages, with the slagging temperature fluctuating in the range of about 90–110 °C in stage III, followed by a rapid drop below 60 °C in stage IV. Furthermore, a digital image monitoring system was used to validate the slag growth process and study the relationship between deposit thickness growth and area expansion. This novel approach provides automated and accurate guidance for each soot blower around the furnace, which reduces soot-blowing steam consumption and avoids serious slagging on the waterwall surface.

Keywords

• coal-fired boiler
• waterwall
• surface temperature measurement
• slagging monitoring
• soot-blowing