Analys av kapacitetsbegränsad kondensor för återvinning av processånga
Examensarbete på grundnivå
has been carried out in collaboration with Preemraff Lysekil which ope rates Scandinavia’s largest oil refinery with an annual capacity to refine over 11 million tonnes of crude oil per year. The steam system at Preemraff is complex but essential for the industry. The project studies the problems of an air-cooled heat exchanger designed to condense low-pressure steam for reuse. The purpose of the project is to investigate the limitation of steam flow to the condenser. The objective is to identify limiting factors as to why the maximum capacity is lower than design specifications. This report describes the function and thermodynamic properties of the condenser based on process specifications. The thermodynamic mechanism of heat transfer was studied such as convection, conduction, and energy balances. A model for the condenser was set up to apply the theory, and a sensitivity analysis was used as a tool to study the impact of operating conditions. The organization had previously conducted a field study that was used in this project in conjunction with measure ment data to evaluate the system in contrast to the theory. The results indicate that there are two contributing factors to the limited capacity. The probable cause is air pockets trapped inside the system and fouling on external finned tubes. Finally, proposed solutions are presented in the conclusion.
air-cooled heat exchanger, convection, conduction, LMTD, fouling, steam