Semicontinuous Separation of Bio-Dimethyl Ether from a Vapor–Liquid Mixture

Abstract

In this work, a semicontinuous system is investigated for the separation of biomass-derived dimethyl ether from a vapor−liquid mixture. This novel semicontinuous system operates in a cyclic campaign and utilizes one partial condenser column coupled with a middle vessel to achieve the separation typically carried out using two continuous distillation columns. The performance of six control configurations based on composition or temperature inferential control were analyzed. Dynamic simulation results demonstrate the effectiveness of the semicontinuous system and its temperature inferential control configuration in achieving the separation objectives, remaining within operational limits and rejecting fresh feed disturbances. Finally, the semicontinuous system is compared to the traditional continuous system from an economic standpoint with the sensitivity of operating cost to middle vessel product target purity highlighted.

Semicontinuous Distillation of Quintenary and N-ary Mixtures

“…By comparing the two processes at different production rates, the impact of the capacity of the system on total costs can be determined. The TAC was calculated using eqs –) assuming a 3-year plant lifetime and 8400 operational hours per year, which has been used in previous studies − where i represents the column tower, reboiler, reflux drums, condensers, pumps, and MVs. …”

“…Based on its repeated success at maintaining steady dynamic performance for ternary, quaternary, and quintenary semicontinuous distillation processes, the “DB” dual composition control structure can be employed for N-ary semicontinuous separation. ,,, …”

“…Based on its repeated success at maintaining steady dynamic performance for ternary, quaternary, and quintenary semicontinuous distillation processes, the "DB" dual composition control structure can be employed for N-ary semicontinuous separation. 3,5,6,8 The semicontinuous distillation process has 4(N − 1) degrees of freedom (DOFs) available for control at any given time. These DOFs are satisfied by these control pairings:…”

“…Industries such as specialty chemical and biorefineries can benefit from this semicontinuous separation process as they operate at low to intermediate flow rates. , Some specialty chemical companies are interested in installing facilities operating between pilot and full-scale throughput in order to increase business in high-value, low-volume chemicals . Recent studies show that biorefineries are moving toward smaller distributed plants to reduce overall transportation costs.…”

Space-constrained purification of dimethyl ether through process intensification using semicontinuous dividing wall columns

“…Pascall and Adams studied semicontinuous distillation for the production of DME and were able to perform a ternary separation with the DME reaction by-products. In two different simulations, they were able to separate DME, methanol and water into three high purity streams (Pascall and Adams, 2013) and CO2, DME, methanol and water into high purity CO2 and DME while combining the methanol and water at the bottom of the column (Pascall and Adams, 2014). To date, the separation of CO2, DME, methanol and water into four high purity streams has not been demonstrated with semicontinuous distillation in the open literature.…”