Abstract
Abstract : South Africa, like most of the developing countries, relies mostly on thermal power generation through its network of coal fired power stations. The South African power utility, under consideration for this research, faces numerous challenges as most of the coal fired power stations have reached mid-life span or are beyond the design life spans. The high demand for electricity has further strained the power plants as little to no maintenance is carried out in an effort to keep the power supply stable. The postponement of the planned outages has resulted in several break-downs on the various systems within the power stations. The constant break-downs within the power utility’s network of thermal generating units has a negative impact on the availability and reliability of the coal thermal power plants. Boiler tube failure is one of the main reasons for most of the forced outages at coal fired thermal power plants all over the world (Bamrotwar and Dr Deshpande, 2014). This dissertation illustrates the cause and effect analysis of boiler tube failures in the South African power generation industry. The dissertation focuses on theoretical background of boiler tube failures and the boiler tube failure mechanism as experienced in industry. The dissertation provides the reader with industry current application of operating and maintenance practices in an effort to reduce the boiler tube failure. The paper highlights the risk management that is associated with boiler tube failures and the importance of lessons learned in the literature review. The research methodology adopted in this study is the review of industry data in order to establish the past performance and current performance of the coal fired power plants in South Africa. The data collected from the South African power utility supplier’s database shows the poor performance of the power generation industry in dealing with boiler tube failure, hence a need for improvement. The objective of the research is to create a database and improve the process flow for dealing with boiler tube failures in the South African industry. Although it is found that the power utility supplier has initiated a boiler tube failure reduction programme, the programme has not been fully utilised due to loop holes within the process flow. There are limitation to the research study such as difficulty in data collection, study period and credibility of collected data as the primary data source is the power utility’s database. A new methodology which is more robust is suggested and as shown in Appendix A. This has a greater success rate in reducing and eliminating loops holes that cause boiler tube failures to be catastrophic. The results considered in this research study, illustrate that the South African power utility supplier’s fleet of coal power stations are underperforming as 1847MW was lost due to boiler tube failures only. The biggest challenge is the fact that the downtime for the respective power stations has increased over the years. The power utility supplier needs to focus on minimising the downtime. According to the power utility supplier there were 169 boiler tube failures across 14 coal fired power stations, from April 2016 to April 2017. Boiler tube failures contributed to about 33.33% of the total power lost, due to breakdowns. The boiler tube failure rate is 1.92 failures per unit in 2016 to 2017 from 88 units in operation. The fleet has a 2.28% unavailability for the period in review. Fly ash erosion is the dominant failure mechanism in the South African power utility supplier’s power stations. Long term overheating is the least failure mechanism within the South African power utility supplier’s power stations. Technical strategies including improving maintenance quality and regular inspections are proposed. Improving the coordination of planned and unplanned boiler outages is suggested. Improving safety and reliability of the boiler operation is proposed.
M.Ing. (Engineering Management)