CHARGE ACCUMULATION IN AN OIL TANK DURING LOADING OPERATIONS

Charge accumulation and relaxation of kerosene have been investigated in a full-sized, 100 kiloliter test rig during pumping operations. Two different experiments were conducted. First, measurements were made a s a constant volume of oil was circulated through the tank via a recir culation loop. The first experiment, while not operationally realistic , permitted a simplified test of the charge relaxation model under a c onstant liquid volume condition. Electrostatic fields was monitored bo th during and after filling. Second, measurements were made under the realistic condition of fresh oil being pumped into the tank from anoth er reservoir. From both experiments, it is found that volume-averaged charge density decreases as liquid depth increases; furthermore, the h ighest surface potential occurs for a fill fraction near 50%. The expe rimental data compare well with the predictions of a model derived und er the assumption of uniform volume charge and simple ohmic relaxation .