(55b) Bimodal Modulation for Enhanced Desalting

The process of crude oil desalting can be considered as two major sub-processes: (1) ideally, homogeneous dispersion of the wash water into the oil followed by (2) deep dehydration of the subsequent mixture. An increase of the overall desalting efficiency results from improvements to one or the other of these sub-processes. The application of bimodal modulation to the desalter power supply allows the operator to adjust the energy supplied to the drop interface as necessary for overcoming interfacial tension while also adjusting the time available for electrostatic field decay as required to minimize the effects of oil conductivity. It has not previously been possible to directly address either of these parameters. It has been shown in both laboratory and field tests that significant improvement in dehydration results from application of these techniques. Similar improvement in desalting efficiency is also seen.