Influence of operational parameters in sour water stripping process in effluents treatment

Sour water are process streams, with high concentrations of hydrogen sulfide (H2S) and ammonia (NH3), absorbed during the crude oil refining process. In order to comply with environmental legislation, and reducing costs, it is treated to remove contaminants, usually in separation columns. Despite stripping be widely found in industrial plants, including refineries, few studies have approached process optimal configurations, to application in different scenarios of sour water stripping. Therefore, this work aimed to verify the process configurations influence in non-phenolic sour water treatment of two typical compositions, and to improve the efficiency, assisted by a virtual plant, in ASPEN PLUS® software. RADFRAC module was adopted to simulate the stripping column with ELECNRTL thermodynamic model. The influence of operation conditions, as boilup ratio (BR), reflux ratio (RR), number of stages (NS), sour water input position (SI), sour water temperature (ST) and pressure (P), the composition itself, and use of steam or thermal load were studied. Results showed that, regardless of the use of steam or thermal load, for bottom stripped water, the increase in BR, NS, and ST promoted a decrease in NH3 and H2S recovery, while the decrease in RR, SI and P reduced them. Use of steam performed less recovery values than thermal load. Process efficiency not changed significantly with composition. Study findings show the optimized configurations in order to obtain a better efficiency process, for a one column system, generating water with low H2S and NH3 concentrations, which allow water reuse, or disposal in accordance with Brazilian legislation.