Method for separating light hydrocarbon from liquified natural gas

Abstract

The invention relates a process for the light ends separation of liquefied natural gas, comprising the following steps: preliminary heating the raw material of liquefied natural gas, separating methane and condensing it, demethanizing and making it liquefy, deethanizing and transferring the gas phase ethane to the ethylene cracking unit through pipe line, and finally getting the liquid phase discharging including weight constituent of dimethylmethane and butane. The invention utilizes part refrigerating of LNG, because it is conserved in low-temperature liquid methane after ethane and propane is reclaimed from LNG; only 60% methane gas is needed to be compressed, so the power consumption of compresser is reduced; it is convenient to store liquid methane because its pressure is low. The ethane from said invention is high output, separation flow process is simple, and equipment investment is only a little, running period is long, and operating cost is cheap.

Description

technical field [0001] The invention relates to the technical field of separation and recovery of light hydrocarbons from liquefied natural gas (LNG), in particular to a method for separating light hydrocarbons from liquefied natural gas (LNG). Background technique [0002] In 2004, the Chinese government formulated a new energy strategy with the core of "optimizing structure, improving efficiency, emphasizing environmental protection, ensuring supply, and developing the west", requiring an increase in the proportion of natural gas in energy composition. In the next 15 years, my country's natural gas consumption is expected to increase from 30 billion m 3 / a grows to 220 billion m 3 / a. [0003] Natural gas deposits are mostly associated with oil and condensate, which are separated during extraction. Condensate and liquefied petroleum gas (LPG) are mainly composed of C 3 ~C 6 Hydrocarbons, natural gas is mainly methane, containing about 10% (mol) of C 2 ~C 3 Hydrocarb...

AI Technical Summary

Problems solved by technology

[0012] 2. In the above patents, all the separated methane needs to be compressed by a compressor, which consumes a lot of power

[0013] 3. The pressure and temperature of methane separated by the above patents are relatively high, which is not conducive to storage

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