Investigation of technical and economic aspects of pre-dried lignite utilisation in a modern lignite power plant towards zero CO2 emissions

Abstract

The pre-drying technology is expected to play an important role in the next generation of brown coal power plants. The integration of the fluidised bed drying system with internal heat utilization (WTA technology) is estimated to bring an efficiency increase of up to 6 percentage points in future brown coal power plants compared to the current state of the art. Furthermore, brown coal pre-drying is considered as an indispensable part in future oxy-fuel brown coal fired boilers. In the present work the potential utilisation of brown coal pre-drying is evaluated based on a realistic reference case scenario. Thermal cycle calculations and economic feasibility studies are carried out for a modern Greek power plant, taken as reference case and for two dry lignite firing cases. In the first co-firing scenario investigated a co-firing share of dry lignite to a thermal share of 25% is regarded. Furthermore, the configuration of a brown coal boiler fired 100% with pre-dried lignite is examined. For all cases, the main economic parameters are calculated including investment costs, cost of electricity, payback period, return on investment. The effect of the CO2 allowances price on the economic feasibility of the considered scenarios is also evaluated.