Effect of Flow Rate on the Corrosion Behavior of API 5L X80 Steel in Water-Saturated Supercritical CO2 Environments

Abstract

The effect of the water-saturated supercritical carbon dioxide flow rate on the corrosion behaviour of API 5L X80 steel at a temperature of 35 oC and pressure of 80 bar was investigated. Tests were carried out with the samples attached to a rotating shaft inside an autoclave. Results indicate that increasing the scCO2 flow rate had no significant influence on the general/localized corrosion rate under the various dynamic conditions considered. The average general corrosion rate was 0.064 mm/year, while the average measured pitting penetration rates were one order of magnitude higher. The size of the corrosion features on the surface of the samples, which were believed to provide an indication as to the size of the condensed water droplets, were much smaller than the calculated critical droplet size needed to be displaced by the flow, supporting the theory as to why flow rate had little effect on the corrosion response.

Mechanism and anti-corrosion measures of carbon dioxide corrosion in CCUS: A review

“… 71 Nevertheless, increasing the velocity of s-CO 2 has no significant effect on the overall/local corrosion rate under various dynamic conditions. 70 And increasing the CO 2 gas flow rate caused a clear reduction in the CO 2 corrosion; since the CO 2 gas is not as corrosive as the liquid, the corrosion rate decreases by the increased gas hold up. 72 Simultaneously, consideration must be given to the variation of flow rate under high-temperature and high-pressure conditions.…”

“… 68 However, some studies showed that the corrosion rate was reduced with the increase of flow rate. 69 , 70 …”