| The oil associated gas and condensate gas in our country contains much ethane. It is a great value to recovery ethane from them. But the ethane recovery device is few and mainly recovery ethane from oil associated gas in our country.The process is simple and the amount is small. Due to the low temperature, CO2in the feed gas can form solids in ethane recovery process, which will affect the safe operation of the equipment. Therefore, the research of ethane recovery process in natural gas containing CO2based on ethane recovery process, CO2freezing control technology and system heat integration technology at home and abroad can improve the level of utilization of domestic oil and gas resources. It can also have a very important significance for realizing the economic development of the condensate gas field.On the basis of the phase equilibrium theory, this paper analyzed CO2solid formation mechanism in the hydrocarbon system. After studying the CO2solid formation condition prediction, this paper proposed the minimum CO2freezing temperature margin of the demethanizer gas and liquid phase when using HYSYS software. After studying the freezing law of demethanizer, the CO2freezing control measures of ethane recovery were put forward.By analyzing the technology characteristics of three ethane recovery processes LSP, RSVE and HPA which can control CO2freezing, this paper established HYSYS simulation process and analyzed the suitability of three processes on three kinds of typical feed gas.In order to improve the ethane recovery process system heat integration, this paper studied on the multi-stream heat exchanger networks optimization design and demethanizer simulation and optimization of RSV process, by taking the feed gas of Tarim proposed ethane recovery device as an example. Put forward a method to design heat exchanger networks use a hot-end threshold problem. Find out the optimum feed and extraction location of the demethanizer and side reboilers.In order to control CO2freezing and improve the ethane recovery, this paper put forward a efficient process named "Liquid Hydrocarbon Reflux process" based on RSVE process using foreign natural gas ethane recovery new achievements, CO2freezing control technology, system heat integration technology. After that, this paper analyzed the suitability of LHR process. LHR process refluxes part of the deethanizer bottom liquid hydrocarbon to the top of the demethanizer with the recycle-split vapor after been cooled. At the same time, LHR process recoveries part of cold energy of the NGL. These make LHR process has a large CO2freezing temperature margin of demethanizer and a better system integration. LHR process can recovery ethane from feed gas contains more CO2. |
