Performance assessment and mass energy balance for regenerative type air heaters

Abstract

The rapid development in South Africa over the last decade and the absence in new-build power plants have put enormous pressure on Eskom to reduce unplanned outages and increase the efficiency and reliability of the power plants. During the development of this study, Eskom was implementing measures to increase the reliability of their power plants through various measures, from coal quality to maintenance strategies and plant optimisation. One part of the plant that attracted most of the focus was the draught plant, which consists of the air heaters, FD, ID and PA fans. Even though not a full part of the draught plant was the fabric filter plant, but this plant had a direct influence on the overall performance of the draught plant. The air heaters at Arnot power station was the focal point of the optimisation as it was struggling with ID fan capacity and ID fans operating in stall condition. An air heater performance test was conducted at Arnot power station to determine the current state of the air heaters after the Arnot capacity increase program was concluded in 2006. The results from the performance test were compared to the original design data specifications to determine the relevant deficiencies which contributed to overall performance issues for the draught plant. The aim of this dissertation is to develop a model that can be used to determine the performance of the air heaters during different operational condition without the hassle of a full performance test. It is also aimed to demonstrate that the variable of the air heater within itself is not only the contributing factor of underperformance but that the boiler also plays any important role. It is also intended to demonstrate the importance of proper combustion within the boiler as well as proper maintenance of the air heaters. The results from the performance test and the air heater simulation model correlated very well with each other. This correlation shows that the model can be used for on load performance assessment by system engineers