Minimum Energy Consumption in Multicomponent Distillation. 2. Three-Product Petlyuk Arrangements

Abstract

We show that the minimum energy requirement for separation of a multicomponent mixture in a three-product Petlyuk arrangement is equal to the minimum energy for the most difficult of the two separations (top/middle or middle/bottom product) in a conventional single column. In the V min diagram (part 1 of this series), this is simply the highest peak. These results are based on an analytical solution for columns with an infinite number of stages, assuming constant relative volatilities and constant molar flows. The previous analytical results for the Petlyuk column are extended to include nonsharp separations, multicomponent feeds, and any feed quality.

Optimal synthesis of thermally coupled distillation sequences using a novel MILP approach

“…Despite its wide use and functionality it is a very energy intensive method of separation, accounting for about 40% of the total energy used in the chemical and petroleum refining industries (DOE, 2005). To this end, the thermally coupled distillation (TCD), in which heat is directly transferred between columns through two streams (liquid a vapor) that substitute a condenser or a reboiler (See Figure 1), has received considerable attention, with savings in total cost between 10 and 50%, when compared to the traditional approach, where simple columns are employed in series to achieve the desired product purities [1][2][3][4][5][6]). …”

“…In the condenser this fact is especially relevant if the most volatile component must be condensed at sub-ambient temperature preventing the use of cooling water. (2) In FTC systems the minimum vapor flow is that of the most difficult separation [5,6]. The thermal couples transfer the vapor between columns and, therefore, some column sections could have large diameters.…”

“…Some of them, without the intention of a comprehensive review are: modification in the number and characteristics of vapor and liquid transfer between columns [60,61]; Simultaneous design of thermally coupled and heat integrated systems [12,[62][63][64], thermodynamic analysis [2,5,6,[65][66][67], generation and analysis of sequences with reduced number of column sections [68][69][70][71], alternatives for columns with one or multiple walls [72,73].…”

Robust Initialization of Rigorous Process Simulations of Multiple Dividing Wall Columns via Vmin Diagrams

“…A promising method to determine initial streams for a rigorous simulation is the V min method [1] presented by Halvorsen and Skogestad [8][9][10] based on Underwood's method [11]. V min diagrams are obtained for only one column depicting different split cases.…”

“…In contrast to that, the V min diagrams will be presented as an effective and robust tool to initialize rigorous simulations for the design of multiple Dividing Wall Columns. This work comprehensively summarizes the publications of Halvorsen and Skogestadt [8][9][10] and Fidkowski and Agrawal [12], with a focus on mDWCs. Example calculations developed by the author of this paper shall help advance understanding of the method.…”