Skid-mounted natural gas liquefaction and purification integrated cold box

Abstract

The invention provides a skid-mounted natural gas liquefaction and purification integrated cold box. The skid-mounted natural gas liquefaction and purification integrated cold box comprises a natural gas supercooling heat exchanger, a natural gas unit, a gas-phase refrigerant unit and a recooling unit, wherein the gas-phase refrigerant unit is used for cooling natural gas in the natural gas unit; the recooling unit is used for making a liquid-phase refrigerant and a gas-phase refrigerant be mixed to form a mixed refrigerant, cooling the gas-phase refrigerant subjected to heat exchange, and returning part of the mixed refrigerant to a natural gas precooling heat exchanger and a gas-phase refrigerant precooling heat exchanger; and the other part of the mixed refrigerant flows back to a liquid-phase refrigerant heat exchanger. The skid-mounted natural gas liquefaction and purification integrated cold box has the following beneficial effects that soldered plate heat exchangers are used as the heat exchangers in the cold box; and meanwhile, a carbon dioxide low-temperature separator is integrated in the cold box, carbon dioxide is separated out through a low-temperature separation method, and thus the equipment investment and operating cost of a natural purification device are greatly reduced. Furthermore, efficient cold distribution is achieved through reasonable refrigerant flow distribution, so that the cold box is made to have high thermodynamic efficiency, and the exergy loss in the heat exchange process is reduced.

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 natural gas liquefaction and purification integrated cold box. 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 other hand, there are ...

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Problems solved by technology

The flow channel of the coiled tube heat exchanger is relatively large, and it is not easy to freeze and block at low temperature, but the manufacturing requirements are high and the investment cost is high; the material of the plate-fin heat exchanger is aluminum, which is easily corroded by mercury in natural gas. The finned heat exchanger has a small flow channel area, and the requirements for the front-end natural gas purification device, especially the carbon dioxide purification device are very high. If the carbon dioxide purification device cannot remove carbon dioxide to a very low content, solid carbon dioxide is very easy to block the plate fin at low temperature The flow channel of the heat exchanger

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