Economically and environmentally efficient triple-column pressure-swing distillation with heat integration and heat pump techniques for the recovery of tetrahydrofuran and n-butanol from waste effluent

Abstract

BACKGROUND

The ternary azeotropic tetrahydrofuran, n-butanol, and water system is always produced from the waste effluent of γ-butyrolactone production units. The separation of this system using economically and environmentally efficient processes is essential for environmental protection and resource recovery.

RESULTS

Two alternative triple-column pressure-swing distillation (TCPSD) processes were developed to separate the ternary azeotropic tetrahydrofuran, n-butanol, and water mixture based on thermodynamic strategies. Then, the process was optimized to obtain the optimal decision variables, with economic and environmental performance metrics adopted as the optimization objectives. Process intensification strategies, including heat integration (HI) and heat pump (HP), were adopted to decrease energy consumption and CO₂ emissions. The results illustrated that HI-assisted TCPSD processes achieve reductions of approximately 11–20% of cost and 15–20% of CO₂ emissions. Furthermore, HP-assisted TCPSD processes yield more substantial improvements, with cost and CO₂ emissions reduced by about 18–22% and 32–40%, respectively.

CONCLUSION

Overall, TCPSD processes incorporating HI or HP technologies demonstrate superior economic and environmental performance compared to the conventional process. © 2026 Society of Chemical Industry (SCI).