This paper presents a system for improving coal-fired power plant’s efficiency through heat rate monitoring and cost analysis. Currently most power plants calculate the rate of efficiency in an offline mode with low accuracy. The optimisation of a power plant operation demands an accurate and quick way of efficiency monitoring.
The developed system is capable of accurate estimations of boiler as well as total power plant efficiency. The boiler efficiency calculations are mainly based on the indirect method of DIN 1942 (Calculations of the heat losses) and on empirical formulas from the literature.

The system performs combustion calculations and through the help of a database with the utilised fuel information estimates the fuel composition and the LHV. As for the LHV calculation a detail statistical investigation took place and more than 20 formulas have been investigated in order to categorize the formulas according to their accuracy for different coal types.

The system mentioned above has been evaluated through the implementation in 2 lignite-fired units using as input data the data from the acceptance tests of the Units during their commissioning. The results s well as cost analysis and forecasts are presented in the paper.