SuperSonic gas Separation technology (3S-technology) was designed to prepare the gas for transportation and to extract different fractions from gas, such as hydrocarbon condensate, propane-butane and ethane. The technology is based on cooling of swirling gas in supersonic Laval nozzle. Due to the implementation of high speed in the nozzle, the temperature of gas can be reduced by 70°C and more, thus ensure conditions needed for condensation and separation of heavy fractions contained in gas. A device, realizes this process, is called "3S-separator". It comprises a stationary swirl body, a supersonic nozzle and a diffuser with selection of condensed fluid.

It has been proved that usage of 3S-separators instead of Joule-Thomson valves makes it possible to ensure higher operating efficiency of associated gas processing devices in any parameters. And it can reduce dew points of water and hydrocarbons of a tank gas and increase the amount of gas recoverable from unstable condensate.

3S-separators make it possible to extract target components from natural gas in wide gas input pressure range from 1.0 MPa to 16 MPa. To ensure the optimum gas temperature at 3S-separators inlet recuperative heat exchangers should be used.

At present 3S-technology is successfully used by several industrial plants in Russia ("Rosneft" JSC, "Gazprom" JSC) and abroad (PetroChina Company Ltd.). The use of this technology in subsea processing plants will enable to carry out gas conditioning in accord with sales gas qualifying standards. Thus, as opposed to currently existing gas cooling technologies, based on using of expansion turbines and refrigerator sets, 3S-technology makes it possible to ensure high equipment reliability and enables to install equipment on the seabed. The more promising area – is use of 3S-technology in projects of getting a high pressure (100 and more atmospheres) sales gas. It is impossible to use conventional gas cooling technologies, because of supercritical conditions of natural gas, under which gas additives condensation is not possible at any temperatures. By ensuring high-speed gas flows in supersonic nozzles, there could be a condensation and separation of natural gas target fractions in 3S-separators, even in a high gas pressure conditions.

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