Recovery of mono-ethylene glycol by distillation and the impact of dissolved salts evaluated through simulation of field data

Abstract

This study was conducted to investigate the operation of a packed distillation column and analyse its performance during the separation of mono-ethylene glycol from water. The column was designed and constructed by the Curtin Corrosion Engineering Industry Centre (CCEIC) and operated in collaboration with a reputable oil company to generate experimental field data. A secondary investigation was then performed into the impacts of dissolved salts within the rich MEG feed upon the purity of the lean MEG product. It was observed through application of the FUG shortcut distillation design equations that six equilibrium stages were required to attain the experimental separations reported under continuous operation of the column. It was further determined that the packing utilised within the column had a Height Equivalent to a Theoretical Plate (HETP) of approximately 0.34 metres when no dissolved salts were present corresponding to an estimated packing height of approximately 1.7 metres. The impact of dissolved salts upon the performance of the column was evident through lower lean MEG purities observed during experimental operation of the column in comparison to salt free trials. The reduction in column performance was reaffirmed by Aspen HYSYS and Aspen Plus simulations of the field data, where salt trials resulted in lean MEG purities noticeably less than corresponding salt free experimental trials and simulated predictions. Overall, it was observed that the presence of dissolved salts during operation led to a reduction in MEG mass fraction of the final lean MEG product by on average 7.2%. The impact of dissolved salts on lean MEG purity was successfully predicted by Aspen Plus simulation with an average accuracy of 1.61% through the inclusion of monovalent salt cations using the ELECNRTL equation of state with modified binary parameters. The reduction in lean MEG purity was attributed to boiling point elevation of the MEG-Water solution and the impact of the dissolved salts on the systems vapour liquid equilibrium.

Design, optimization and economic analysis of a monoethylene glycol recovery process: salt precipitation and vacuum operation

“…Moreover, this is the first study that presents a full analysis and optimization for the equipment used in MEG-R-P as well as detailed cost analysis for each part of the process, while the available results from literature ignored all these parameters. 25,38 The overall project cost of 23.3 MMUSD for MEG-R-P producing 99.9 wt% purity is two to four folds lower than values reported in the literature. Kim et al 27 developed a MEG-R-P producing 97 wt% purity in a process contains flash drum, two parallel atmospheric distillation columns, a vacuum FLS, and a distillation column.…”

“…9,23 The atmospheric distillation column is installed after the RV to increase the purity of MEG by further water removal. 24,25 The SS which has a similar FS design, but it treats part of rich MEG in the vacuum RV, while the reaming amount is bypassed and combined later with the treated MEG. 26 The presence of ionic salts in the rich MEG could enhance the HI efficiency, 21 and they are controlled by changing the mixing ratio between treated and by-passed stream.…”

A systematic approach for design and simulation of monoethylene glycol (MEG) recovery in oil and gas industry

“…MEG-R-P was optimized for high purity in terms of distillation column operating parameters (pressure and temperature), which was ignored in previous studies. 16,30 The present study offers an effective MEG-R-P that includes a six-stage distillation column operated under a reflux ratio of 0.562 and a pressure of 0.05 bar. These operational conditions recovered up to 99.9% of high purity MEG.…”

“…Moreover, different published designs showed significant discrepancies in the equipment designs, process outcomes, and design considerations. 2,10,12,[14][15][16] Teixeira et al 2 used the concept of exergy analysis to determine the optimum energy requirement for the MEG-R-P. The proposed designs were based on testing different recovery concepts using ASPEN HYSYS software.…”

“…The best-developed design consists of atmospheric distillation to remove water fraction, followed by a flash separator and second distillation column that is operated under vacuum conditions (0.2 bar) to maximize the MEG purity up to 93 wt%. Zaboon et al 16 compared the output of the MEG-R-P from experimental and simulation perspectives. The experimental part consists of only a 6-stage distillation column operated at 140 kPa and recovered MEG with purity in the range of 70 wt% to 80 wt%.…”