TROUBLESHOOTING CO_2 ISSUES USING A SIMULATOR: A CASE STUDY

摘要

A Gulf Coast fractionation and ethane treating facility began having severe CO_2 excursions in their treated ethane in late January 2010. The excursions began shortly after a new gas feed was added to the fractionation facility. The treated ethane CO_2 concentration would increase from a steady 10 ppmv or less to 1000+ ppmv. The facility contacted Dow Oil & Gas Technical Service & Development (TS&D) to evaluate the events, determine the cause of the CO_2 excursions, and implement a resolution. Upon reviewing plant data for several of the events and comparing to ProComp 8 simulations, Dow concluded the excursions were the result of a slow increase in the concentration of CO_2 at the absorber inlet. The additional moles of CO_2 reacting with the amine caused the maximum liquid phase temperature in the absorber to increase and to move higher in the vessel. The increase in CO_2 leakage into the treated ethane was a consequence of the changes in the absorber temperature profile. Dow provided guidance to the facility on the maximum inlet CO_2 concentration the absorber could handle at any absorber inlet feed gas rate. No excursions have occurred since the guidelines were accepted and implemented. This paper reports the effect of increased CO_2 concentration at the absorber inlet on absorber performance and on treated gas composition. Three actual CO_2 events were evaluated by reviewing plant data and compared to ProComp 8 simulations.