A simulation-based prediction model for coal fired power station condenser maintenance

Abstract

South African coal-fired power stations (CFPSs) are faced with special challenges. These include ageing infrastructure, increased maintenance requirements and reduced funds. A unique solution is therefore required whereby station performance can be maintained or even enhanced at minimum cost. A simulation-based model could help improve the effectiveness of operations and minimise downtime. In this study such a model was developed for a South African-based CFPS. The model was built using a semi-empirical thermohydraulic model. The results of the simulation were verified against measured station data and were accurate to within 5 %. This calibrated simulation model for the fully integrated CFPS operation was then used to investigate condenser maintenance. The practical question that had to be answered was when is the best time to clean and maintain the condensers as they have a significant impact on performance of the CFPS. The monetary effect of early, late or non-maintenance was quantified. The model showed that the resulting loss in profit due to maintenance schedules followed an exponential trend and is therefore extremely time-sensitive. A loss in profit of R600 000 for a 60 MW unit occurred if the condenser was maintained 30 days too early or too late and R2.5 million if maintained 60 days too early or late. When extrapolated to all South African power stations, this value increases to R250 million if all stations are maintained 30 days too early or too late and R1 billion if maintained 60 days too early or too late. The application of the simulation-based approach showed that a verified semi-empirical model provides significant insights into CFPS performance. The approach provides a credible platform for decision making, process predictions, scenario investigations, and optimising operations. Effective condenser maintenance scheduling provided significant value to station personnel. Although this study focussed on a condenser-specific application, a similar approach can be applied to other components of the station using the same model. The work will be presented at the ICUE conference in Cape Town in November 2019. An article on the work was also prepared for the journal, Applied Thermal Engineering. The article is given after the Abstract. It is suggested that the reviewer read the article first as it is a concise summary of the Dissertation. It will make reading the rest of the Dissertation easier.