Objective The ethane recovery and treatment unit in Jiaxian County has issues such as suboptimal heat integration solutions, complex refrigeration system, and suboptimal process parameters, resulting in high energy consumption of the system. This study aims to reduce the energy consumption of the ethane recovery and treatment units.
Method Taking the ethane recovery unit in Jiaxian County as an example, an analysis was conducted on its heat integration situation based on the theory and methodology of system heat integration-pinch technology. Based on the findings of this analysis, an improved process with high heat integration degree—RSVHT, was proposed.
Result Firstly, the improved process achieved efficient heat integration of hot streams such as raw material gas and external reflux gas with cold streams such as demethanizer streams and dual-temperature propane refrigerants in multiple heat exchangers. While maintaining an ethane recovery rate of 95%, the propane consumption was reduced by 50.8%, and the total compression work of the system was reduced by 3 641 kW, achieving a high energy-saving rate of 19.9%. Secondly, the improved process eliminates the reboiler for separate heating of the demethanizer and the screw-type propane refrigeration system by adopting a single set of propane refrigeration system to provide dual-temperature cold sources of −8.7 ℃ and −38.3 ℃, simplifying the refrigeration process. Thirdly, by optimizing the temperature of the low-temperature separator and other process parameters in the process, the amount of propane refrigerant was further reduced.
Conclusion The research results provide an effective scheme for improving of the heat integration process of the ethane recovery unit in Jiaxian County, and also provide technical references for the design and optimized operation of domestic ethane recovery units.
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