AC/DC platform and composite electrodes combined with a low-reactance power unit

NATCO ELECTRO-DYNAMIC DESALTER electrostatic desalting technology provides enhanced multistage mixing in a single vessel. These crude oil desalters combine five technologies in a single, compact, reliable, and effective solution:

• NATCO DUAL POLARITY electrostatic treater
• NATCO LRC-II smart interface
• cocurrent and countercurrent washwater flow
• electrodynamic mixing
• composite electrodes.

Use AC and DC fields to remove salt and water from crude oil

The NATCO ELECTRO-DYNAMIC DESALTER technology uses the extremely efficient HiFlo spreader to evenly distribute the incoming wet crude and create a uniform vertical flow upward through the treater. This method eliminates grid bypass and local recirculation areas.

The bulk water and larger water drops are coalesced and separated by gravity in the weaker AC field that exists between the grounded water phase and the electrodes. The stronger DC field between the electrodes causes rapid movement of the remaining small water droplets through electrophoretic attraction, causing the water droplets to collide, coalesce, grow, and settle by gravity.

Improved mixing with washwater

Improved mixing makes the single-stage desalter as efficient as two conventional AC desalters in series. Washwater is added upstream of the mixing valve in the desalter's inlet piping and countercurrent through the overhead water pipe. The overhead water is added directly between the composite electrodes. The power unit modulates the applied electrostatic field, causing electrodynamic mixing.