Natural gas liquefaction and light dydrocarbon separation integrated process system and technology

Abstract

The invention discloses a natural gas liquefaction and light dydrocarbon separation integrated process system and process. The process comprises the steps that after natural gas is subjected to precooling, a gas phase and a liquid phase are drawn out of a main heat exchange cold box and enter a washing tower, the tower top gas phase enters the main heat exchange cold box to be cooled, gas-liquid separation is carried out through a washing tower return tank, the liquid phase enters the washing tower to provide the cold reflux for the washing tower, and the gas phase returns to a liquefaction section of the main heat exchange cold box; after being subjected to throttling pressure reduction, the bottom stream of the washing tower enters a dethanizing column, the top gas phase of the dethanizing column enters a precooling section of the main heat exchange box to be cooled, and gas-liquid separation is carried out through a return tank of the dethanizing column; according to low-temperature liquid-phase ethane, on one hand, the cold reflux is provided for the dethanizing column, and on the other hand, part of the low-temperature liquid-phase ethane is extracted to serve as ethane refrigerant to be stored, and the rest is pressurized and conveyed to the liquidation section of the main heat exchange cold box through a pump; propane and butane are pressurized through a propane pump and a butane pump respectively and then mixed to be conveyed to the cold box, extraction is carried out after precooling, methane and ethane stream is combined after throttling, then propane, butane, methane and ethane return to the main heat exchange cold box to be liquefied together, and LNG is produced.

Description

technical field [0001] The invention relates to an integrated process for the liquefaction of methane-rich hydrocarbon gas and the separation of light hydrocarbons, in particular to a process system and method for natural gas liquefaction, condensate oil removal and ethane / propane refrigerant production. Background technique [0002] In the existing hydrocarbon separation technology (patent CN103031169), the raw natural gas is extracted from the main heat exchange cold box after pre-cooling, and the heavy hydrocarbon separation tank is used to separate heavy hydrocarbons to separate heavier components such as propane and butane; The hydrocarbon scrubber directly washes the raw natural gas to remove heavy hydrocarbons. The raw gas enters from the bottom of the tower, and the heavy hydrocarbon washing liquid is sprayed from the top of the tower. After the heavy hydrocarbons are removed, the gas phase enters the main heat exchange cold box for liquefaction. The first method sep...

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Problems solved by technology

[0004] The invention provides an integrated process system and process for natural gas liquefaction and light hydrocarbon separation, which are used to overcome the problems of long process, many equipments and complicated control in the prior art.

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