R&D Technologies for Acid Gases Extraction from Natural Gases

Abstract

Abstract This paper describes main processes used for removal of CO2 from natural gases and some results of under R&D technologies of acid gases extraction from natural gases, including the method of 3S-technology (SuperSonic Separation technology). There are various methods of acid components extraction from the natural gas: adsorptive, adsorptive, membrane, cryogenic and their various combinations. All mentioned technologies are notable for necessity to use a large number of accessory equipment, including bulky one that leads to the high capital investment costs and great operational costs, and also to the costs for restoration of adsorbents/absorbents, clearing of membranes, etc. These circumstances make the existing technologies inapplicable in terms of cost efficiency. At the same time, a significant progress was recently being made in the development of new low-temperature processes of extracting CO2 from natural gas. Low-temperature processes are specially promising in processing of gases with high CO2 content. Several low-temperature processes of CO2 removal are presently known: –Ryan Holmes method;–Controlled freeze zone method (CFZ);–Cryocell method (Cryocell);–Sprex method (Sprex);–Gasdynamic separation of gas mixtures (3S-separation). All 5 above mentioned low-temperature processes of acid components extraction will be considered and analysed in this paper. While the main focus is on the analysis of 3S-separation technology. 3S-separator is a low-temperature supersonic separator, based on natural gas cooling in a supersonic swirling flow. Supersonic flow is implemented using a convergent-divergent Laval nozzle. In this nozzle, rapid cooling of gas takes place due to the conversion of flow potential energy into kinetic energy. This workcontains a detailed description of 3S-technology. Someexistential schematic diagrams of devises based on 3S-separation will be presented in this paper. The advantages and limitations of this technologyhave been investigated during the study. Currently3S-separators have been successfully operatedat severalgas processing facilities. Experimental studiesof CO2 separation from naturalgaswere carried out onthe test unitwith the3S-separator, designed for 6000 nm3/hour gas flow. Duringtests it has been shownthat the technologymakes possible theseparation of CO2 inthe carbon dioxide crystallization zone. The performed tests demonstrated that it is possible to achieve less than 3% mol CO2 concentration in the inlet gas.