Designing a Packed Dividing Wall Column for an Aromatics Processing Plant

Abstract

This paper introduces a comprehensive design method assembled using facilities of a commercial software package that complemented by Excel programs, which contain own column dimensioning and well established cost estimation procedures, enables proper assessment of the industrial viability of a dividing wall column (DWC) equipped with corrugated sheet structured packings. The heart of the performance simulation tool is a detailed four-column model that in conjunction with a simple, theoretically founded short-cut method providing reliable initial values for liquid and vapor splits and a simple but effective objective function for design optimality indication allows determination of the adequate stage and reflux requirement of a DWC. The proposed dimensioning method enables a close approach in accuracy to that required at the stage of conceptual design for purposes of making a bid by an equipment manufacturer. Compared to a two-columns-in-series configuration, as employed in an aromatics processing complex within a refinery, a DWC equipped with state-of-the-art structured packing and auxiliary internals requires approximately 43% less energy to deliver three fractions at required product specifications. This, accompanied by savings of nearly 51% based on total annualized costs, indicates that implementing a DWC could lead to a significant increase in profitability of aromatics processing plants.

Conceptual Design of Highly Integrated Processes – Optimization of Dividing Wall Columns

“…The resulting design has TAC of 119 941 € p.a. Even in case the sequential procedure would have determined this solution the difference in TAC would not exceed 10 %, such that previous claims , , that the simplified objective function approximates TAC well, are supported by the current case study.…”

“…After a thorough review of the available design approaches two selected approaches for sequential and simultaneous optimization are compared based on a more detailed assessment. The sequential optimization procedure, which follows the suggestions from Dejanovic et al [39], combines a manual sensitivity study with the optimization capabilities of a commercial simulator to minimize a simplified objective function based on the number of equilibrium trays and the reflux ratio. After an initial comparison of several thermodynamically equivalent substitute models, the fourcolumn configuration is further utilized for process optimization in the sequential approach, as it provides the highest flexibility [31,38,70,72].…”

“…The investment costs for the column shell of the DWC are estimated based on the maximum vapor load in each section, while the vapor streams on both sides of the dividing wall are added up. In addition, a surcharge of 20 % is added to the investment costs to account for the more complex construction with the dividing wall, which is in accordance with Dejanovic et al . Finally, all DDoF are optimized simultaneously in a series of successively relaxed NLP problems minimizing TAC.…”

Dimensioning Multipartition Dividing Wall Columns

“…Estimation and adjusting the pressure drop of parallel sections within a packed DWC can be done during the conceptual design phase by using a robust and reliable method introduced most recently by Dejanović et al [7]. As demonstrated in the present paper, the packed DWC-dimensioning method, developed originally for common three-product situations, can easily be extended to deal with much more complex multipartition wall internal configurations, such as encountered when designing a DWC for obtaining four products.…”

Design and control for a dividing‐wall column with a partial condenser for pretreating an industrial multi‐component reformed gasoline mixture

“…As mentioned above, a four‐point temperature control structure works well for the separation of ternary or quaternary mixture with a total condenser . However, research on control of a DWC with a five or more component feed is relatively scarce, and is usually encountered in pretreating an industrial multi‐component reformed gasoline (IMCRG) mixture.…”