Study On The Modeling And Optimization Of Safety Instrumented System Based On Maintenance Strategy

With the scale of industrial processes increasing largely, reliability and maintainability of safety instrumented system become more and more important. Our country’s power production is an important industry to support the national economy, safe and efficient electricity production have always been what reliability and maintainability researchers concern. However, the maintenance strategy in domestic power industry relies mostly on periodic maintenance, the maintenance intervals rely solely on engineering experience, and there is no actual data validation link, lacking of theoretical support. Also, the selection of the maintenance strategy is relatively simple, condition-based maintenance strategy,which is used widely in weapons and equipment, aerospace, petroleum, chemical industry,is not common in the practical application of plant.This paper takes thermal power and nuclear power as the background, selects the sub-function-furnace pressure protection,of the main fuel trip in thermal power plant and the sub-function-large axial displacement to stop turbine,of nuclear steam turbine protection to do the research. First, for the two sub-functions, according to actual operating data in plants, applying reliability and security theory, based on IEC61508 and IEC61511 standards, draw their fault tree models and make safety assessment to obtain their safety integrity levels; then apply periodic maintenance strategy, considering reliability, availability and cost, adopt multi-objective optimization strategy, optimize the maintenance interval of the sub-function-furnace pressure protection within the specified time frame,which setted in "thermal control maintenance procedures"; next, combined with periodic maintenance strategy and condition-based maintenance strategy, according to the actual characteristics of the sub-function-large axial displacement to stop turbine,propose five specific maintenance strategies,providing a reference comments for maintenance work in nuclear plant.Finally, through the safety assessment and maintenance strategy studies of nuclear power plants and thermal power plants, obtain the main factors affecting the security of thermal power plants and provide improved orientation...