Process unit and method for removing heavy hydrocarbon during liquefaction process of natural gas

Abstract

The invention discloses a process unit and a method for removing heavy hydrocarbon during the liquefaction process of natural gas. The process unit comprises a precooler, a hydrocarbon liquid separator, an expansion machine, a heavy hydrocarbon removal tower, a second throttle valve, a hydrocarbon removal ice chest and a dethanizer which are sequentially connected. The process unit has the following active effects: compared with a throttle valve, the obtained natural gas has lower temperature by filling the natural gas to the expansion machine for expansion and temperature reduction by utilizing the pressure of the natural gas; the expansion machine can be connected with a compressor or an electric generator to recycle part energy so as to realize energy conservation; an ethane heat exchanger and the hydrocarbon removal ice chest are utilized to realize full exchange of energy in the process unit, so that an external cold source is not needed, investment is reduced, and energy conservation and consumption reduction are realized; the process unit has excellent heavy hydrocarbon removal effect, removes the heavy hydrocarbon component in natural gas as far as possible, facilitates follow-up liquefaction process, effectively avoids freezing and blocking of heavy hydrocarbon and meets the demand of liquefaction of natural gas.

Description

technical field [0001] The invention relates to a process device and method for removing heavy hydrocarbons by using self-pressure expansion and refrigeration of natural gas after precooling in the natural gas liquefaction process, especially for the process device and method for removing heavy hydrocarbons in the large-scale natural gas liquefaction process. Background technique [0002] Natural gas must undergo advanced pretreatment before liquefaction, including the removal of heavy hydrocarbon components, so as to effectively avoid the freezing and blocking caused by impurities in the natural gas liquefaction process, especially the condensation and freezing of heavy hydrocarbon components in low-temperature environments. Blockage of pipes, valves and plate-fin heat exchangers and other equipment. The existing methods for removing heavy hydrocarbons from natural gas at home and abroad mainly include rectification method and adsorption method. In these two methods, natura...

AI Technical Summary

Problems solved by technology

High-pressure natural gas contains huge pressure energy, and in the process of regulating pressure through pressure regulating equipment, this part of pressure energy is often wasted in vain. In addition, due to the rapid pressure drop and temperature drop of natural gas, the requirements for pressure regulating equipment and pipeline equipment also very high

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