The deaerator of a power plant may experience severe two phase steam/water problems especially during re-start of the power plant following a unit trip. Unless suitable control strategies are adopted, cavitation in the suction area and choking in the deaerator can occur. Cavitation can cause expensive damage to the feedwater pumps while choking will interrupt the operation of the deaerator. We have developed a model which can predict the transient behaviouit of the deaerator plant for possible cavitation and choking. In this paper we propose a scheduling control for deaerator operation based on this model. This scheme utilises operational status and process variables to predict possible cavitation or choking, then takes the necessary action to avoid the loss of head in the suction area and high velocity of steam in the deaerator equaliser. The simulation results show that the control scheme will ensure safe operation even during re-starts of the power plant.
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