Tracing the Economic Boundaries between Amine, Hybrid and Membrane Technologies for Natural Gas Sweetening

According to the position of Iran in the global gas reserves and the development of the country, natural gas sweetening process has a significant importance. Natural gas often contains contaminations such as CO2 and H2S that must be removed or lowered in content to the standard limits, before being delivered to the gas pipelines. Development of membrane technology in the world in the recent decades has made this technology more competitive with the conventional gas sweetening processes. The aim and objective of this study is providing economic boundaries between amine, hybrid and membrane technologies for sweetening of mixed gases containing CH4, CO2 and H2S. Simulation of the amine plant has been done using the Aspen-Hysys software and the membrane system has been precisely modeled and simulated using the MATLAB software. Configuration of membrane system was considered as a 2- stage process using a recycled flow. The influence of different parameters, including gas inlet pressure, permeate pressure, composition and the effect of inlet gas flow on the cost of membrane and amine systems, has also been studied. The results showed that for the CO2/CH4 feed, economic boundaries include three zones: Amine, membrane, hybrid and in all range of concentrations the membrane unit is economically efficient. For the CO2/H2S/CH4 feed, economic boundaries include two zones: amine & hybrid that all gas refineries in our country are placed in the economic area of amine now.