Abstract

The amine sweetening process is one of the most matured technology that deals with acid gas removal. However, energy consumption is considered as a prominent concern for amine absorption process due to the significant energy requirement for amine re-boiler. In previous paper (SPE-192731-MS), we discussed the effectiveness of two promising debottlenecking approaches for amine sweetening process namely; lean vapor compression (LVC) and rich vapor compression (RVC). This paper objective is to study the effectiveness of Rich Solvent Recycle (RSR) and low stripper operating pressure on pre-combustion amine absorption process.

The study used ProMax 4.0 simulator, which has been well proven to have a high accurate prediction for amine sweetening processes calculations. For RSR approach, the rich solvent leaving the bottom of absorber has been divided into two streams in which one is recycled back to the bottom of the absorber and other stream continues to the same normal path as for conventional amine process configuration. The flow ratio between recycled stream to the forward stream has been optimized to provide the minimum overall duty. For the stripper operating pressure approach, the impact of lowering the pressure on re-boiler duty has been studied for two different plants. For all scenarios, the treated gas acid gas concentration and system operating window were kept as constant. The proposed approaches have been simulated in two existing two amine-sweetening plants currently under operation by Petroleum Development Oman (PDO) for H2S capture (i.e. Plant-A) and the other one for CO2 capture (i.e. Plant-B). .

The results indicate that rich solvent recycle (RSR) debottlenecking approach potentially could result in lower re-boiler duty by maximizing the solvent/acid gas contact at the bottom of the contactor with a potential energy saving of 20% for Plant-A. The ratio between recycled streams to the forward stream has been manipulated to achieve optimum energy consumption. For stripper operating pressure, it has been found that the re-boiler duty decreased due to lower operating pressure.

The study has focused on pre-combustion amine absorption process unlike most of the published studies, which focused on post-combustion processes. In addition, in this paper live plants data were used to examine the simultaneous impact of different parameters.

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