Abstract:

Installation of automatic soot blower controls have been made at Mid American Energy, Homer City plant and at International Paper recovery boilers. The systems utilize strain gage instrumentation to measure ash deposits on boiler pendants. Boiler load, steam temperatures, draft, and other data are used to add intelligence to the automatic control system. Experience with this system had demonstrated significant steam savings while keeping the boiler components cleaner than with traditional soot blowing controls. Reductions in boiler outages due to clinker formation, eroded tubes, and over stressed tubes is an expected benefit from this system. The Homer City installation also includes water cannons to keep the furnace section clean, thus controlling furnace exit gas temperature and resulting slag accumulations. A thermodynamic model is also used at Homer City to set permissive levels for soot blower operation. This integrated system provides a cleaning system that operates only when and where necessary. Also, the paper will discuss high temperature gages installed at the NRG Huntley station. These gages are installed in the boiler penthouse area.

Conclusion

The ISB system at Homer City has been successfully operating for a number of months using the SuperHeater Fouling Monitor strain gages as a key input. The SmartCannon system is in full automatic operation. Since the water cannons have been tuned and placed into automatic, the utilization of the wallblowers has not occurred. Reheat temperature is maintaining the plant desired temperature. The Accutemp acoustic pyrometer shows that the FEGT is maintaining an average of 2150° F. The Superheater Fouling Monitor is indicating that no significant slag accumulation is occurring in the Platen Secondary Superheater or the Secondary Superheater sections of the boiler.

The goal of the system is to run 100% high sulfur coal in the unit. Due to plant operating philosophy this has not been attempted yet. Coordination between water cannon operation and the retractable soot blowers is optimizing the boiler efficiency and steam production. The SmartLances will clean in normal steam mode except in extreme cases as noted by the Superheater Fouling Monitor when steam is not capable of sufficient cleaning. In these cases the SmartLance will operate utilizing the water nozzles for aggressive cleaning of these sections in the area of slag formation.
The success of the system provides a model for future ISB systems.