USC Technology in CCT Boilers applying
Biomass Cofiring

Presented by Knud Bendixen, BWE, at Power-Gen Europe
June 28-30 2005, Milan, Italy

Abstract

After 1980 it has become more and more normal to design utility power units for supercritical steam data. Through the 1990s this development entered the USC (Ultra Super Critical) range meaning live steam pressure higher than 275 bar at full plant load. The reason behind this is to reach still higher efficiencies and by doing so at the same time qualify as the best CCT (Clean Coal Technology).

The whole process cycle including all its components will be influenced in the design by the high steam data. In Denmark this development has been done stepwise over the years to make it possible to maintain always a high availability.

The Boiler Island will be based on a BWE tower type design having tangential firing for pulverized coal or biomass. This means multifuel burners capable of firing as well coal as biomass. The combination firing will give a very efficient power conversion of biomass fuel. The island will be a one train solution at least up to 700 MW size.

There is now a wide experience basis for the design of these boilers. The tangential firing system has been developed to handle also biomass fuel in large quantities. The fuel must be prepared in a way to make it possible to grind it to pulverised fuel.