Maintenance strategy for a coal-based steam power plant equipment: A graph theoretic approach

Abstract

Maintenance cost and downtime losses of a steam power plant can be reduced by adopting a proper mix of maintenance strategies that ensure its reliable availability. The type of maintenance for different equipment in a power plant is decided as per its importance in terms of attributes such as maintenance efforts, loss of production, safety/reliability and efficiency. In the worst situation, failure of hypothetical equipment would affect all these attributes and would thus have maximum criticality. In general, the failure of equipment would not affect all the attributes and therefore its criticality will have some intermediate value. The level of criticality would decide the importance of the power plant equipment and choice of appropriate maintenance strategy. The procedures reported in literature are empirical co-relations to combine major attributes into a single index and have the limitation of using a number of attributes simultaneously. Using Graph theory and the Matrix method, a systems-based mathematical model has been developed for determining the maintenance criticality index of equipment of a coal-based steam power plant. The proposed model does not have any limitation either regarding the number of attributes or the interactions among these. Being a mathematical model, it is also not subjective. Plant equipment is categorized into four groups as per the ranking of its maintenance criticality index and a suitable maintenance strategy is recommended for each group. A step-by-step procedure for finding the criticality index has also been proposed in the paper. Using this procedure, an appropriate maintenance strategy for any other type of power plant/industry can also be recommended.