Electric current fluctuation often occurs at the electric desalting tank in a refinery when the tank-cleaning oil is blended with crude oil as feedings.In order to solve this problem,the pretreatment of tank-leaning oil and the operation status of primary electric desalting tank are investigated on the spot and optimized.It is indicated that preventing crude oil from forming a stable emulsion is the core solution.Therefore,some measurements are taken as follows.Flocculants such as polyaluminum chloride and polyacrylamide are not added again in the purification process of tank-cleaning oil to prevent them from forming more stable emulsion with crude oil.The iron content of crude oil before stripping is controlled in the range of 0 to 5 mg·kg-1 to prevent iron ions from increasing the stability and conductivity of crude oil emulsion.The injection amount of demulsifier is controlled in the range of 10-15 g·t-1 in advance.The emulsification layer at the electric desalting tank is drained on time.Through implementing these measures,the atmospheric-vacuum distillation unit has refined continuously tank-cleaning oil for 139 days while the electric current at the primary electric desalination tank has remains stably,and the discharge index of salt-containing sewage meets the standard.
atmospheric-vacuum distillationtank-cleaning oilcrude oilblendingelectric current
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