VORTEX NATURAL GAS GATHERING AND GAS PROCESSING
WELLHEAD GAS THERMAL CONDITIONING
The vortex wellhead gas thermal conditioning provides for the gas temperature increase in the natural gas gathering system, thus eliminating the likelihood of hydrate formation or condensation of heavy hydrocarbons vapor.
The process includes reservoir gas non-freeze pressure reduction in the proprietary Energy and Mass Separating Self-Heating Vortex Tube that replaces a wellhead choke and the subsequent removal of the generated vortex cooling load.
The warmed vortex cold gas is then combined with the vortex hot flow.
The Energy and Mass Separating Vortex Tube centrifuges all the water droplets and the hydrocarbons vapor condensed in the chilled core of the vortex flow to the VT periphery. The vortex cold gas exit the VT as a single phase flow dried to the dew point equal to the vortex cold gas temperature. The liquid carried with the vortex hot flow is separated prior to the hot gas mixing with the warmed vortex cold flow.
CASE STUDY: The raw wellhead gas at 2,300 to 3,700 psi with flow rate of up to 600,000 scfd undergoes non-freeze pressure drop (down to some 250 psi) in the Self-Heating Vortex Tube. The VT cold outlet (some 50% of the VT inlet flow) at the temperature of - 76⁰F is directed to the gas-ambient air heat exchanger with defroster where the cold gas is warmed (depends on the ambient temperatures) to, at least, 14⁰F. The warmed vortex cold outlet and the vortex hot outlet at some 65⁰F are combined; the combined flow is directed into the gas gathering manifold.
There are two gas-ambient heat exchangers on the site, each operating in 12 hr. cycle.
NATURAL GAS LIQUID RECOVERY
The Vortex Low Temperature Separation (VORTEX) is a natural gas processing refrigerating technology to enhance NGL (natural gas liquid) recovery at plants that currently use a Joule-Thomson (JT) cooling with external refrigeration. The core of the VORTEX is the proprietary One Flow Vortex Tube (OFV) where the processed hydrocarbon feed is chilled under combined JT and vortex cooling i.e. to temperatures well below those in the Joule-Thomson valve. Additional cooling translates in a greater hydrocarbon liquid output. Alternatively, the same NGL recovery can typically be obtained with reduced expansion ratios, thereby offering the opportunity for reduced compressor cost.
The VORTEX advantage over JT valve based recovery depends on the feed gas composition and gas inlet and outlet pressures. As an example, foe a relatively heavy gas (Methane 81 Mole%) at 900 psi inlet pressure and 250 psi discharge the VORTEX demonstrates up to 17% increase in Ethane condensation and some 10% increase in propane recovery (based on HYSIM™ simulation).
Both JT and VORTEX Low Temperature Separation process arrangement consists of the same equipment. The JT base process plant can be converted to a VORTEX plant just by replacing the Joule-Thomson valve with One Flow Vortex Tube (no other equipment replacement/changes needed).
The VORTEX can also be scaled down and utilized in smaller applications such as booster compressor fuel gas conditioning etc.