Separation of 1,2-propanediol and ethylene glycol is an important task for coproduction of these two compounds via hydrogenolysis of glycerol for the purpose of utilizing this biodiesel byproduct. These two compounds exhibit close-boiling behavior which requires many stages of a regular column and also large energy consumption to meet stringent product purity specifications. In this paper, several alternative designs are investigated in order to save steam cost and also total annual cost of this separation task. Alternative designs considered include multieffect distillation, heterogeneous azeotropic distillation, and extractive distillation. Significant reductions of 38.3% in steam cost and 30.6% in total annual cost as compared to the regular column can be obtained by a design flowsheet via an extractive distillation system using triethylene glycol as entrainer. Methods for further improving the economics of this extractive distillation system have also been investigated. A simple worthwhile improved design is to preserve the energy from the hot entrainer to preheat the fresh feed via a feed-effluent heat exchanger. With this simple improvement, a further 12.8% reduction in steam cost can be made as compared to the original extractive distillation system.
Glycerol utilization is an important research topic because of recent surging biodiesel production through transesterification of vegetable oils and animal fats. One of the valuable products from glycerol is gained through esterification with acetic acid to produce triacetin. Hasabnis and Mahajani proposed an entrainer-based reactive column configuration with stoichiometric feed ratio to obtain high selectivity and conversion. This paper corrects the kinetic parameters in Hasabnis and Mahajani to better describe this reaction system. A more effective reactive entrainer for this reactive distillation system is also proposed to better carry water to the top of the column. The other modification is to assume feed compositions of the glycerol and acetic acid feed streams containing some water as impurity as opposed to idealistic pure feed assumptions. The operation and control of this system are also investigated. The proposed tray-temperature control strategy is able to maintain product purity despite disturbances from throughput and feed composition changes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.