Theoretical and industrial aspects of amine reclaiming unit to separate heat stable salts

Abstract

In this study, a thermal vacuum distillation amine reclaimer unit was industrially and theoretically investigated to remove HSS from a salty amine stream. The presence of ions in the salty amine solution limits application of computer simulation tools to study the process. A thermodynamic equivalent scheme was used for thermal vacuum distillation amine reclaimer, for first time and the simulation results were totally conformed to experimental and industrial data. The effect of critical parameters namely reclaimer vacuum pressure, re-circulation flow rate and HSS amount on performance of thermal amine reclaiming was investigated based on increasing amine solution quality, amine recovery, energy usage, and waste amine rate. The results showed that the required energy is mainly attributed to thermal energy rather than mechanical energies (i.e., pump equipment). It was also found that the required energy for a thermal vacuum reclaimer is lower than that for an electro-dialysis process with a value of 12 kWh/kg HSS. Therefore, the thermal vacuum reclaiming process is more economical comparing to the electro-dialysis when only energy requirement is concerned. In addition, the results showed that a decrease in reclaimer pressure leads to higher amine concentration in vapor and liquid phases and lower energy usage. Higher amine recovery can also be obtained by heating feed stream with amine-waste re-circulation and an increase in re-circulation flow rate would increase energy demand in both condenser and heat inputs.