Overview – NATCO DUAL FREQUENCY Electrostatic treater
Dehydrate and desalt upstream crude oil processes
The NATCO DUAL FREQUENCY electrostatic treater uses both AC and DC power to provide significant process improvement, often more than 100%, over conventional AC electrostatic technologies. It uses our proprietary load-responsive controller—the NATCO LRC-II smart interface—and a three-phase high-frequency power unit to generate a customized electrostatic field that can be optimized for any crude oil.
The treater can be delivered as a heater treater, providing heating and dehydration in a single vessel and eliminating the need for an externally heated heat transfer fluid. It can also be provided as a degassing treater, eliminating the need for a separate degasser.
Treat cost effectively
The NATCO DUAL FREQUENCY treater reduces capex and opex through its higher treatment capacity, higher tolerance to wet crudes, and increased dehydration performance. Moreover, it allows reduced demulsifier dosage, less washwater usage, and a lower operating temperature.
Improve performance with real-time control
The LRC-II interface improves emulsion resolution via voltage modulation, enabling operation at the optimal voltage for multiple crude feedstocks, while managing upsets more rapidly and effectively. Parameter setup in the treater power unit can be updated from the LRC-II interface in real time while the unit is operating.
The HiFlo spreader improves vessel hydraulics and enhances performance to support higher process capacity.
A two-pronged approach to remove formation water from crude oil
The NATCO DUAL FREQUENCY treater 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 separate by gravity.
In desalter applications, washwater is added upstream of the mixing valve in the treater’s inlet piping. Together with the electrophoretic movement of the water droplets, this provides a very high degree of mixing with the brine. Superior mixing and improved dehydration make the NATCO DUAL FREQUENCY treater much more effective than conventional AC desalters of similar size.
Use of a high base frequency for the electrostatic field provides stronger electrostatic forces. Low-frequency amplitude modulation of the field improves conditions for water droplet coalescence, further enhancing dehydration and desalting efficiency.
We also retrofit existing AC treaters to improve their capacity and enable lower operating temperatures and emulsifier dosages.
Boost your electrostatic treater
A high-efficiency power unit upgrades NATCO DUAL FREQUENCY units to improve facility opex by increasing treater reliability and simplifying maintenance.
With the new unit installed,
- treaters operate at higher temperatures and with wider power variations.
- new sensors monitor trends in the health of key components, enabling warnings before as well as during an upset condition.
- unit maintenance can be performed without removing it or draining the oil.
- an AgoraGateway ruggedized edge computing device enables optional remote, real-time health monitoring and life-of-asset collaboration.
Application of NATCO DUAL FREQUENCY Electrostatic treater
Three primary components are packaged in a single oil-filled enclosure. First is the power electronics, designed to produce a variable amplitude and variable frequency voltage field. For many field installations, this is a key feature of the technology, as it enables an optimization of the applied voltage. Second, the medium-frequency power unit provides for the increased secondary voltage known to promote effective coalescence. Third, the secondary voltage is rectified to produce electrophoretic movements of the water droplets, which improves both dehydration and desalting. A DC field is created between the electrodes, enabling droplet motion and efficient coalescence. Simultaneously, an AC field is created between the electrodes and the grounded water phase, enabling bulk water removal in the weaker AC field.
Traditional AC technologies typically experience rapid voltage decay or arcing when operated in very wet crude oil service. This decay reduces the effectiveness of the dehydration process by reducing the voltage lower than what is required for effective dehydration.
By applying a higher-frequency electrostatic field, the treater reduces this voltage decay and enables effective dehydration, thus overcoming the voltage decay experienced with conventional 50/60-Hz transformers. The specific oil and water properties, operating temperature, and formation solids all combine to create a unique emulsion that often can be very difficult to resolve. To break the emulsion, the patented NATCO DUAL FREQUENCY treater uses a microprocessor-based system that includes the LRC-II smart interface and defines the pattern and amplitude of the voltages that are applied to the electrodes. The proprietary LRC-II smart interface enables selection of the shape and amplitude of the voltage waveform to optimize coalescence of the water droplets, leading to an effective resolution of the emulsion and low water content in the treated crude.