Effect of Carbon Dioxide on Hydrogen Sulfide Scavenging

Abstract

Abstract Effective removal of hydrogen sulfide (H2S) is one of the challenging problems associated with the production of natural gas. Since H2S is often present in natural gas along with varying levels of carbon dioxide (CO2), selective removal of H2S from sour gas in the presence of CO2 is very important for cost effectiveness of a scavenging operation. For over ten years, triazine based scavengers have been successfully applied in the sweetening of natural gas. However, observations of the effect of CO2 on the scavenging capacity of triazine based scavengers have not been very consistent. Initial documentation and case histories on performance of triazine based scavengers by Dillon [1,2] reported that CO2 did not have any effect on the H2S scavenging capacity of triazine. However, recent studies by GRI [3] indicate that CO2 significantly reduces the H2S removing capacity of triazine. To address this discrepency, this paper critically evaluates the effect of CO2 on the scavenging performance of a triazine based H2S scavenger. Results from controlled laboratory experiments, using a wide range of CO2 partial pressure and H2S to CO2 ratios indicate that CO2 has very little effect on the H2S scavenging performance of a triazine based H2S scavenger. Field data supports the observations made in the laboratory experiments.