Damage Mechanism Analysis and Risk Assessment of Pressure Vessel Absorber, LP Flash Column, Rich Solution Heater at CO2 Removal Plant Unit

Abstract

Field-X is one of the largest gas contributors, where gas customers are companies that contribute to the sustainability of the economy. X-field natural gas has a high CO2 content of 23%, the CO2 removal operation is intended to reduce the CO2 content so that it has a high heating value. This is because CO2 with levels> 5% can affect the heating value gas, toxicity and is very corrosive, especially for customers to further process the product. In the gas purification process in field X, the Absorber pressure vessel, LP Flash Column and Rich Solution heater have a major role in the CO2 absorption process. The analysis results show that the actual damage mechanism of the pressure vessel with the standard amine treating on API RP 571 has a difference, especially the damage mechanism of amine corrosion in the three pressure vessels and chloride stress corrosion cracking on the LP Flash Column. The highest corrosion rate value is 0.604 mm / year in 2020 due to an increase in the amount of HCO3- in the form of acid condensation (HSAS) which can react with Fe due to changes in process temperature through the corrosion rate model Y = -0.0556x + 4,6359 (head) and Y = -0.0161x + 1.3682 (shell) in the pressure vessel. From the criticality matrix, there are 2 pressure vessels at the risk rating for medium and 1 pressure vessel for high medium, so that the inspection / maintenance response that needs to be done is corrective maintenance at intervals every 6 years and the scope of the inspection is in the medium category. Polynomial model Y = 0.0007X2 - 0.0099X + 3,7452 (head) and Y = 0.0005X2 - 0.0842X + 3,3876 (shell) as a prediction model for amine corrosion rate at temperatures ranging from 40 to 1300C shows the difference in the graph between the actual and the API RP 581 standard is because the prediction standard of corrosion rate is used for amine treating in H2S and CO2 systems while the actual polynomial graph is used for prediction of corrosion rate for amine treating in CO2 system without H2S.