Analysing desalter performance and improving crude blending capacity with multi-phase instrumentation and control

摘要

Not all refineries are the same and,as such,the challenges with blending crude feedstocks vary between facilities.Fluctuation in crude supply can be beneficial,however it can also bring significant operational challenges during the desalting process that can have an impact further downstream into other parts of the distillation unit.Opportunity crudes are becoming a more attractive option for refiners looking to improve flexibility,maximise operating margins,increase distillate yields or convert high sulphur fuel into diesel and gasoline,but they are not without their difficulties.Whether it be oil sands,shale or condensate,higher total acid number(TAN)or increased levels of elemental impurities and contaminants such as waxes,solids,iron and vanadium all of these characteristics can lead to processing issues.The efficient removal of these impurities along with salts and water(BS&W)from crude feedstock is imperative to maintain reliable operations,prevent unplanned shutdowns and outages,and reduce corrosion and fouling.Foremost of these challenges is to monitor and manage the position and quality of process fluids,including emulsion,upstream of the distillation tower;namely,the desalter.Whether the process involves inline or intermediate blending,the use of accurate and reliable level or interface control devices(LIC)in the desalter can reduce and in some cases eliminate process problems resulting from unwanted carryover or carry under.