A Novel Methodology for Online Analysis of Amine Solution Degradation Caused by Fly Ash

Abstract

Two research goals were set for this study. (1) The first goal was to develop a reliable and cost-effective online analytical technique to measure amine solvent concentration, loading, and to quantify the amine degradation process based on Gas Chromatography (GC). (2) The second goal was the investigation of amine degradation in the presence of fly ash, which includes: the identification of proper chemistry of degradation; and, the identification and quantification of the degradation products of the amines. For this study, aqueous monoethanolamine (MEA) and aqueous methyldiethanolamine (MDEA) have been selected. To accomplish the first goal, an online analytical technique to quantify the amine solvent chemistry based on Gas Chromatography (GC) was developed and set up in the lab. An automatic liquid sample injection system was attached to the GC to study the impact of the concentration of fly ash on the degradation process of two well-known amines (MEA and MDEA) by measuring the concentrations of amine, water and carbon dioxide (CO2). The flow system was equipped with filters to avoid the introduction of large particles into the GC column. A solvent back-flush system was used to allow for automated cleaning of the particulate filters. GC was then calibrated for the amine and water using various concentrations of aqueous amines (MEA and MDEA), and various CO2 loaded aqueous MDEA solutions and aqueous solutions of ammonium bicarbonate (NH4HCO3) were used to calibrate the GC for quantification of CO2 using a Total Organic Carbon / Total Inorganic Carbon (TOC/TIC) analyzer. To accomplish the second goal, two kinds of fly ash samples were collected from a coal burning power plant. Fly ash samples collected from the power plant were analyzed by SGS Canada Inc. ASTM methods were used to estimate the ash percentage, moisture content and elemental composition of the fly ash (silica and other metal oxides). A lab scale experimental setup was designed and developed to observe the influence of fly ash on amine-based solvents (MEA or MDEA) degradation.