The regenerative-amine process removes hydrogen sulfide (H2S) and carbon dioxide (CO2) from natural gas, refinery gases and synthesis gas. Hydrogen sulfide can be reduced to low sulfur levels. The process can also be applied to remove H2S, CO2 and carbonyl sulfide from liquefied petroleum gas or natural gas liquids (NGL) to low levels. Bulk CO2 removal from synthesis gas with flash regeneration is another application.
The process sequence-ADIP/Claus/SCOT-can be used advantageously with an integrated ADIP system that handles selective H2S removal upstream and the SCOT process treating the Claus offgas.
The ADIP process uses aqueous solutions of the secondary amine, di-isopropanolamine or the tertiary amine, methyl di-ethananolamine. Amine concentrations up to 50%wt can be applied. The process has low observed corrosion rates and a controllable foaming tendency of the solvent due to an optimized design. Its line-up can be very diverse, depending on the application. High integration of separate process units is possible.
The simplest system resembles those of other amine processes. The ADIP liquid treating consists of an extractor followed by mixer/settlers for COS removal. Common regeneration for separate amine absorbers is often applied. Solvent composition will be optimized for customer requirements.
For a typical design, the co-absorbed hydrocarbons from the absorber (1) are flashed (2) from the solvent and used as fuel gas after treatment (3). The solvent is flashed again (4) to release CO2 from the enrichment absorber (5), thereby improving the acid-gas composition from the regenerator (6) to the Claus unit.
Operating conditions: A very wide range of treating pressures and contaminant concentrations can be accommodated. Sulfur specifications of 100 mbara H2S in gas and 10 ppmw in liquid hydrocarbon streams can be met. In liquid hydrocarbon, COS can be removed down to 5 ppmw. Improved Claus feed gas quality can be met by improving the H2S/CO2 ratio in the acid gas. Bulk CO2 removal from a high percentage to several percentage points is easily attained.
Licensor: Shell Global Solutions International B.V.