Technoeconomic analysis and feasibility of co-solvent mixtures in the liquid-liquid extraction of aromatics

Abstract

It is desired to improve the efficiency of liquid-liquid extraction processes in the fuel industry by reducing energy consumption and operational costs as well as reducing risk to health, safety and the environment. Co-solvent mixtures for extraction consisting of butane-1,4-diol, propane-1,2,3-triol (glycerol), and 2-methylpentane-2,4-diol (hexylene glycol) were assessed in terms of capital costs, operating costs and total annual costs relative to a baseline process that is employed for the liquid-liquid extraction of toluene from n-heptane. Commercial solvents such as sulfolane, morpholine-4-carbaldehyde (NFM), and dimethyl sulfoxide (DMSO) were used for the baseline processes that were simulated in ASPEN Plus V10. The capital costs ranged between 5.8-6.2 million US dollars, while the energy intensity ranged between 1000 - 1400 kJ/kg. The total annual costs for all solvents studied varied between 2.4 - 2.6 million dollars. The results highlighted that these co-solvent mixtures may offer some benefits in terms of total annual cost when the impact of solvent choice is holistically considered.