Prevention and control technology of carbon dioxide freezing and blockage in the light hydrocarbon recovery process of natural gas
To reduce the risk caused by CO2 freezing and blockage in the light hydrocarbon recovery process,the RSV process adaptation to CO2 content in feed gas was increased.Based on the formation pattern of CO2 solids,the logistics and equipment of the solids were verified through solid tracking.The influence of different process parameters on freezing and blockage margin was studied through sensitivity analysis and phased thawing measures of different sequences were proposed.It was found that the undercooling-induced backflow of the top gas and the dry gas in the demethanation tower is a flow prone to CO2 freezing and blockage,of which the highest risk exists in the second demethanation plate.The column pressure of the demethanation tower and the temperature of the cryogenic separator are the most sensitive factors for CO2 freezing and blockage margin.As CO2 content in raw gas changes,the corresponding thawing measures vary.The solid CO2 precipitation can be controlled by increasing the column pressure and lowering the temperature of the cryogenic separator.Compared with the RSV process with the same ethane recovery,the improved RSVF process not only increases the freezing and blockage margin but also reduces the total energy consumption.
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