Bi-phase (Scott-T) transformer double voltage AC electrostatic coalescer
An electrostatic coalescer apparatus for separating water from a crude oil emulsion comprises a vessel housing having a cavity, an inlet for receiving a crude oil emulsion and outlets for water and purified crude oil. First and second pairs of electrodes are positioned in the vessel cavity. A first Scott-T transformer circuit is coupled to the first pair of electrodes and a second Scott-T transformer circuit is coupled to the second pair of electrodes. The first and second Scott-T transformer circuit receive as an input a 3-phase power supply and output a 2-phase high voltage signal pairs of electrodes. The 2-phase voltage generated between the first pair of electrodes is of the same amplitude and phase as the voltage generated between the second pair of electrodes via the respective Scott-T transformer circuits. A method comprises steps performed during operation of the apparatus.
1. A method removing water and soluble impurities from a crude oil emulsion comprising:
introducing the crude oil emulsion into an electrostatic coalescer apparatus having a vessel with first and second pairs of electrodes;
generating a homogenous bi-phase AC voltage signal between electrodes of the first and second pairs of electrodes; wherein water present in the emulsion aggregates and separates from the crude oil emulsion by exposure to the high voltage signal within the vessel; and
removing the aggregated water from the vessel of the apparatus,
wherein the homogenous bi-phase AC voltage signal between electrodes of the first pair of electrodes is generated by a first Scott-T transformer circuit and a second and the homogenous bi-phase AC voltage signal between electrodes of the second pair of electrodes is generated by a second Scott-T transformer circuit.
2. The method of claim 1 , wherein the wherein the electrodes in the first pair and the electrodes in the second pair extend in a horizontal orientation.
3. The method of claim 1 , wherein the electrodes within each pair of electrodes receive AC signals that are shifted by 90 degrees with respect to each other.
4. The method of claim 1 , wherein the first and second Scott-T transformer circuit each include a main transformer and a teaser transformer that taps the main transformer in a 1:1 ratio.