Energy Analysis of the New Dual Pressure Low-Temperature Distillation Process for Natural Gas Purification Integrated with NGLs Recovery

The increase of the global energy demand, a scenario in which natural gas plays a key-role, together with the availability of natural gas reserves with high CO2 and/or H2S contents have been two important drivers for the recent studies and developments of new low-temperature processes for natural gas purification, in order to allow the profitable exploitation of low-quality gas reserves that up to some years ago were not considered suitable for their commercialization. When dealing with natural gas, not only acidic gases are present in the main stream, but also hydrocarbons heavier than methane (ethane, propane, n-butane, etc…). These substances have to be removed from the produced gas for the dew point control of the sales gas. Moreover, they are widely used for petrochemical productions and their recovery can be profitable for natural gas producers. In this work, an energy analysis is carried out in order to assess the energy requirements for the recovery of Natural Gas Liquids (NGLs) during natural gas purification at low-temperatures. The results are compared with the ones obtained when traditional processes are used for the same purpose, in order to define the trade-off between the two technologies, extended to the overall production chain, under different possible feed stream compositions. Results prove the feasibility of low-temperature purification processes when dealing with gases having high amounts of acidic compounds and different concentrations of NGLs.