Method and equipment for recycling light hydrocarbon in oilfield associated gas through liquid nitrogen refrigeration

• Main Authors: SUN HEZHONG, YU ZHIYAN, GE YUMING, WANG JIANJUN
• Format: Patent
• Language: Chinese; English
• Published: 23.11.2016
• Subjects: BLASTING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; HEATING; LIGHTING; LIQUEFACTION SOLIDIFICATION OF GASES; LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS; MANUFACTURE OR STORAGE OF ICE; MECHANICAL ENGINEERING; MIXTURES BY PRESSURE AND COLD TREATMENT; REFRIGERATION OR COOLING; WEAPONS

The invention provides a method for recycling light hydrocarbon in oilfield associated gas through liquid nitrogen refrigeration. The method comprises the steps that feed gas coming from an oilfield is subjected to separation and water removal and then compressed to 1.0-1.5 MPa, and then the feed gas is dried till the water dew point is lower than -50 DEG C; and the pressurized and dried feed gas is subjected to first-time low-temperature gas-liquid separation at the temperature ranging from -20 DEG C to 0 DEG C after being subjected to first-time cooling, and gas and liquid light hydrocarbon are obtained; the gas obtained after separation and liquid nitrogen are subjected to heat exchange, the liquid nitrogen is converted into gaseous nitrogen, and meanwhile the gas is subjected to second-time cooling; the gas obtained after second-time cooling and the gaseous nitrogen are subjected to heat exchange, third-time cooling is completed, and the temperature ranging from -60 DEG C to -20 DEG C is finally achieved;