System and method for using liquid-state mixed hydrocarbon cooling capacity and simultaneously increasing associated gas recovery rate

Abstract

The invention discloses a system and method for using liquid-state mixed hydrocarbon cooling capacity and simultaneously increasing the associated gas recovery rate. The system comprises a pre-separator, a compressor, a cooler, a primary condenser, a primary separator, a molecular sieve, a mixer, a heat exchanger group, a steam-liquid separator, a mixed hydrocarbon storage tank and a pressurizing machine, wherein the heat exchanger group comprises a first heat exchanger and a second heat exchanger; the pre-separator, the compressor, the cooler, the primary condenser, the primary separator, the molecular sieve, the mixer, the first heat exchanger, the second heat exchanger and the steam-liquid separator are sequentially connected in a forward direction; a liquid outlet of the steam-liquid separator is connected with the first heat exchanger in a reverse direction, and is then connected to the mixed hydrocarbon storage tank; a gas outlet of the mixed hydrocarbon storage tank is connected with the pressurizing machine; the pressurizing machine is then connected to the mixer; a gas outlet of the steam-liquid separator is connected with the second heat exchanger in the reverse direction, and is then connected to the primary condenser. The system and the method provided by the invention have the advantages that the energy consumption is obviously reduced; the goal of increasing the yield can also be achieved.

Description

technical field [0001] The invention relates to the technical field of recovery of associated gas, in particular to a system and method for increasing the recovery rate of associated gas while utilizing the cooling capacity of liquid mixed hydrocarbons. Background technique [0002] Associated gas, also called oilfield gas, is a flammable gas mixture that accompanies crude oil spillage during oil extraction, and its components are usually methane, ethane, propane, butane, etc. Due to its complex recovery and reuse process but it cannot be discharged directly, and the environmental protection requirements in the past were relatively low, so most oil fields currently burn it directly, and the discharge and combustion of associated gas cause serious pollution to the environment. Energy waste, and a large amount of greenhouse gas emissions caused huge environmental pollution. [0003] The currently used process technologies for associated gas recovery are mainly compression + c...

AI Technical Summary

Problems solved by technology

[0004] Since the associated gas contains a large amount of mixture of light components such as methane and ethane, part of the methane and ethane will be dissolved in the low-temperature product (mixed hydrocarbon) due to the entrainment and dissolution of hydrocarbon substances during condensation under pressure. The recovered low-temperature products (mixed hydrocarbons) are usually stored in uninsulated LPG (liquefied petroleum gas) tanks. As the ambient temperature causes the temperature of the LPG storage tank to rise, small molecular weight gases such as methane and ethane dissolved in low-temperature mixed hydrocarbons Precipitation, the pressure in the tank will gradually increase, so the traditional process often adds a pressure regulating valve to the LPG storage tank to maintain the pressure of the storage tank, and the methane and ethane discharged from the LPG storage tank will entrain some products above C3 that we need to recycle. yield loss

In order to avoid production loss, there is also an improved process of introducing this part of gas into the inlet of the compressor to participate in recirculation, but this improved process also has a large pressure difference between the product pressure and the inlet of the compressor, and the pressure energy of the circulating gas is not fully utilized, making the compression The machine did some useless work

[0005] The solution of the present invention aims at the above-mentioned problems and improves the existing small-scale associated gas recovery process for liquid hydrocarbon cooling capacity and cycle gas pressure energy, which is not fully utilized and the recovery rate of mixed hydrocarbons in the traditional process is low.

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