Calcium Alginate-Based Carbon Composite Adsorbents for Lean Methyldiethanolamine Reclamation: Laboratory to Pilot Scale Testing and Validation

Abstract

Calcium alginate-based carbon composite (CAC) adsorbents have been proved to effectively remove total organic acid anions as HSS anions, metal ions, and organic degraded products from lean methyldiethanolamine (MDEA solvents) used as solvent in natural gas sweetening unit. During the material developmental phase, the CAC adsorbent was synthesized and utilized to remove various contaminants, including heat stable salts (HSS), organic degraded products, and heavy metal ions from lean MDEA using a lab-scale adsorption setup. Based on the results, a "demo-scale" fixed bed adsorption unit was designed and simulated using adsorption model to predict breakthrough behavior. In the current work, the efficiency of the CAC adsorbent in removing HSS and total organic acid anions were investigated. Analysis of treated samples demonstrated the removal efficiency of the adsorbent under plant scale conditions. Further experiments performed at lab scale indicated the effectiveness of the adsorbent in the removal of bicine from lean MDEA samples. This work provides a framework for future testing and comprehensive process performance evaluation of adsorbents for lean MDEA reclamation in actual plant conditions. A fast, simple, and reliable scale up procedure for fixed bed adsorber developed earlier was validated through this work.