Minitype skid-mounted single-level mixed refrigerant natural gas liquefaction system and method thereof

Abstract

The invention discloses a minitype skid-mounted single-level mixed refrigerant natural gas liquefaction system and a method thereof. The method comprises the steps that natural gas is compressed and cooled by a natural gas supercharge skid; impurities are removed from the natural gas by a deacidification and dehydration skid; the natural gas is cooled by a first stage heat exchanger, then enters a heavy hydrocarbon separator, is cooled and liquefied by a second stage heat exchanger after heavy hydrocarbon is removed, and enters a liquefied natural gas separator after depressurized to liquefied natural gas storage pressure by a throttling valve, so as to form liquefied natural gas; flash steam returns to the heat exchangers to provide cooling capacity; a mixed refrigerant enters a second stage gas-liquid separator after supercharged and cooled by a mixed refrigerant compression skid; the gas phase refrigerant is throttled and cooled after cooled by the two heat exchangers, and provides the cooling capacity for the second stage heat exchanger; and the liquid phase refrigerant is throttled and cooled by the throttling valve after cooled by the first stage heat exchanger, and mixed with the refrigerant from the second stage heat exchanger to provide the cooling capacity for the first stage heat exchanger. The system and the method are simple in a liquefaction process flow and low in energy consumption, facilitate the equipment skidding, and have better adaptability to different gas sources simultaneously.

Description

technical field [0001] The invention belongs to the technical field of chemical engineering and cryogenic engineering, and in particular relates to a small skid-mounted single-stage mixed refrigerant natural gas liquefaction system and a method thereof. Background technique [0002] As the main fossil energy in the world, natural gas, oil and coal account for a large proportion of primary energy. Natural gas is a high-quality clean energy, and more and more countries have begun to pay attention to the development and utilization of natural gas resources. [0003] With the continuous optimization of my country's energy structure and the continuous growth of natural gas consumption demand, coupled with the current situation that most of my country's natural gas fields are not large, the gap between my country's natural gas supply and demand is constantly increasing. It is predicted that by 2020 my country's natural gas supply gap will reach 1000×10 8 m 3 . [0004] On the ...

AI Technical Summary

Problems solved by technology

However, for small skid-mounted natural gas liquefaction plants, the mixed refrigerant liquefaction process is relatively complicated

In the existing technology, the patent publication number CN102477327A, the patent titled "a small and medium-sized natural gas liquefaction process", discloses a small and medium-sized natural gas liquefaction process. In this process, the mixed refrigerant adopts two-stage gas-liquid separation, and there are three Heat exchanger, the process is more complicated, not suitable for small skid-mounted natural gas liquefaction plant

Patent Publication No. CN102445052A, titled "A Biogas Liquefaction Process and Device for Scattered Source Points", uses a double-mixed refrigeration cycle to liquefy biogas from scattered gas sources. Since the process consists of two separate refrigeration cycles , more equipment, complex process, which is not conducive to skid equipment, and the composition of biogas and natural gas are quite different, so it cannot be applied to small skid-mounted natural gas liquefaction equipment

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