Method and system for recovering ethane decarburization tail gas in natural gas ethane recovery project

The invention provides a method and a system for recovering ethane decarburization tail gas in a natural gas ethane recovery project. The system comprises an inlet separator, a three-stage centrifugalcompressor, a first-stage air cooler, a second-stage air cooler, a third-stage air cooler, a second-stage separator, a third-stage separator, an outlet separator, an iron-based wet-process fine desulfurization device, a molecular sieve dehydration device, an activated carbon adsorption device, a propane refrigeration device, a flash separator and a food-grade carbon dioxide refining device. According to the method, aiming at the process characteristics of high carbon dioxide content, rich H2S, low pressure, high yield and few impurities of the decarburization tail gas, process technical routes of multi-stage centrifugal pressurization, inter-stage fine H2S removal, medium-high pressure separation, molecular sieve dehydration, activated carbon fine adsorption, propane shallow cold liquefaction, rectification purif