Simulação do processo de adoçamento do gás natural por DEA e recuperação do enxofre pelo processo Claus

Abstract

Natural gas (NG) is an important energy source due to its abundance and lower greenhouse gas emissions compared to other fossil fuels. However, the presence of acidic contaminants such as hydrogen sulfide (H2S) in NG is undesirable due to operational, environmental, health and safety issues. Thus, NG processing plants use the sweetening process to remove this acid gas and produce sweet gas under commercial conditions. In addition to making NG safer and more suitable for commercialization, the separation of H2S from NG can be advantageous from an economic point of view, as H2S can be used in the production of sulfur through the Claus process. Thus, this work aimed to analyze and evaluate the main process variables and their influence on the performance of natural gas sweetening processes by DEA (diethanolamine) and sulfur recovery by the Claus process, using the Aspen HYSYS® software. For the sweetening stage, the temperature of the amine in the column feed, the number of stages and the mass concentration of amine input were evaluated in the absorption column, while the parameters studied for the regeneration column were the number of stages, the feeding stage and reflux ratio. As for the sulfur production stage by the Claus process, the molar flow rate and air inlet temperature were analyzed in the thermal stage, while in the catalytic stage the inlet temperature in the reactor and the efficiency of the type of catalyst (Alumina and Titania) were evaluated. The results showed that, for the absorber column, increasing the number of stages and the amine concentration favored the absorption process, while increasing the amine temperature had the opposite effect. In the regeneration column, it was found that a greater number of stages and a higher reflux ratio provided more efficient desorption, but feeding the amine to lower stages of the column hindered the process. In the sulfur recovery process, the results indicated that the air flow has a parabolic effect on the sulfur conversion, and the air inlet temperature favors this conversion. In the catalytic step, it was found that sulfur conversion is maximized at lower temperatures, and the Titania catalyst proved to be more advantageous. The optimization of these parameters resulted in a sweetening unit capable of producing 21350.5 kg/h of sweet gas with an energy potential of 307 MW, while consuming about 16.2 MW. The sulfur recovery unit achieved a sulfur conversion of over 97% and produced more than 1400 kg/h of sulfur, requiring around 3.6 MW to operate.