MONO ETHYLENOGLYCOL REGENERATION UNIT: EXPERIMENTAL DATA, THERMODYNAMIC MODELING AND PROCESS SIMULATION
Hydrate inhibitor. Phase balance. Electrolyte thermodynamics. UNIQUAC. ENRTL. Process simulation.
Mono ethylene glycol (MEG) is used as an inhibitor of the formation of gas hydrates, its regeneration being indispensable to the economic and environmental viability of the process. Adequate parameterization of thermodynamic models is essential for the satisfactory description of the operations involved in regeneration. For this, confidential experimental data and over the entire range of conditions - temperature, pressure and composition - of the industrial process are required. Experimental liquid-vapor balance (ELV) data for the water + MEG + NaCl system were determined at pressures of 35, 65 and 101.3 kPa, using a modified Othmer boiler. After selection based on the deviation test using the UNIQUAC model (Universal Quasi – Chemical Activity Coefficient), the approved data were used for the parameterization of the ENRTL (Electrolyte Nonrandom Two – Liquid). An inversion in the phase behavior due to the addition of sodium chloride was observed for regions concentrated in MEG. Experimental data of solid-liquid equilibrium at temperatures between 293.15 and 403.15 K were also determined. An inversion of solubility with temperature was observed for regions rich in MEG. The NaCl solubility data were correlated using excess properties and were also applied in the parameterization of the ENRTL. The duly parameterized model was applied in the simulation of the MEG regeneration unit in the commercial simulator AspenPlus v11. Emphasis was given to the flash separator with removal of solids and the distillation column, aiming at describing the separation of water and sodium chloride present in the MEG.