Saturday, July 7, 2007
Amine is a solvent widely used in removal of H2S and CO2 in natural gas. They are generally called gas sweetening and acid gas removal. Generally H2S and CO2 absorb and react with amine in the absorption tower will then be regenerated in the regeneration tower. Regenerated amine will then return back to absorption tower. H2S and CO2 flashed from regeneration tower will be send to thermal oxidizer (TO) and it will then be destroyed in the TO. In case the H2S is significant, the H2S will normally sent to Sulfur Recovery Unit (SRU) to recover Sulfur as byproduct.
There are number of software such as ASPEN HYSYS, SULSIM, PROMAX, AMSIM, etc available in the market which have been widely used by process engineer to simulate the entire amine loop. In HYSYS, there are Li-Mather model and Kent-Eisenberg model available for amine system. Which model shall be used ? There are ideal and non-ideal thermo package, which thermo should be used ?
Li-Mather is a fundamental and rigorous model whilst Kent-Eisenberg method is more empirical. With sufficient study and field data backup with Li Mather model and limitation of Kent-Eisenberg method (limited working envelop), it is advisable to use Li-Mather method for design purpose. Designer can always advisable to counter check with Kent-Eisenberg method.
The non-ideal themo package is taking into accounts of kinetic effects. Hence, non-ideal thermo package is generally adopted in the event feed contains significant amount of CO2 (slow reaction). As for feed dominant with H2S, then they should be minimal impact to the results as the reaction is fast.
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