Control of Contaminates & Degradation Products in Amines During Sour Gas Treatment

Abstract

Abstract Objectives and Scope The objective is to control contaminants in amine systems such as heat stable salt, degradation products, hydrocarbons, particulates and injection chemicals etc. through chemical analysis and process operation. Interpretations of lab results and corrective action in plant to help us to monitor, control and improve the performance by minimizing loss of amine in the system. Methods, Procedures and Processes Contaminants are substances which enter the process and "pollute" the amine. Amine contaminants can be grouped into five categories; (1) Heat stable salts, (2) Degradation products, (3) Injection chemicals, (4) Hydrocarbons and (5) Particulates. Degradation Products are contaminants in solution where the molecule is broken down or changes its chemical form. Amines considered for this study are Diethanolamine (DEA) used in LNG plant and Methyl diethanolamine (MDEA) used in OAG and IGD plants. Amines should be color free and devoid of particulate matter. This is achieved through activated carbon and mechanical filters so that amine quality is within established limit. Results, Observations and Conclusions Laboratory analyzes amines sample (DEA & MDEA) for various contaminants by simple analytical techniques using titrators, pH meter and Gas chromatograph. The analytical data for amine strength since 2013 i.e. in case of DEA the average is 20.1 % within the range of 18-22 % and for MDEA, the average is 45 % and the range is 40-50 % with marginal exception on some occasions. The foam tendency and foam stability data for last three years are optimum indicating minimum contamination. Chloride and Iron which are precursor to HSS & degradation products are monitored on monthly basis and are well below the maximum control value. HSS in amines were low which indicates the stability of amine. The lean amine after regeneration to strip out H2S and CO2 is passed through mechanical filter to remove fine particles and suspended solids which is further treated through activated carbon filters to remove hydrocarbons, anions, cations, impurities etc. Laboratory analyses are vital links for smooth operation of amine system. Simple chemical analysis helps us to understand and give timely response for process control. Historical data gives the perspective for spotting trend of sampling, analysis and possible errors. Proper design of mechanical and carbon filters helped us to maintain amine system free of contaminates and healthy minimizing amine loss. The low level of contaminants in amine system ensures integrity of process equipment and associated units. Novel/Additive Information This simple analytical techniques and process control helped us to maintain the quality of amine and integrity of plant. The same approach is applicable to any gas treatment plant and can be applied there.