Remixing Analysis of Four‐Product Dividing‐Wall Columns

Abstract

Dividing-wall columns can separate multicomponent mixtures and offer large energy savings over conventional column sequences. The separation of a mixture of four alcohols was studied in a Kaibel column and a fully extended Petlyuk column or Sargent arrangement, respectively. The flow paths of intermediates are different so that the Sargent arrangement could save more energy. Remixing of intermediates is unavoidable in the Kaibel column because each of them cannot detour all around both ends of the dividing wall. The Sargent arrangement exhibits the desired detouring paths and the remixing of intermediates is alleviated but still occurs in the prefractionator and the middle column. Finally, an alternative configuration of the Sargent arrangement is proposed which presents a better thermodynamic efficiency.

Numerical and Experimental Research on a Kaibel Divided-Wall Column: Design and Steady-State and Dynamic Operation

“…The remixing of ethanol and n -propanol can be discovered in the prefractionator. In a three-component DWC, the remixing of the intermediate is avoidable due to the detouring route of the intermediate . However, the detouring route cannot be obtained for every single intermediate (ethanol and n -propanol) because the sharp split of ME/PB is performed in the prefractionator.…”

“…The Kaibel divided-wall column (KDWC) that separates a four-component mixture with a single wall was first proposed in 1987 and attracted increasing academic interest until Skogestad et al numerically investigated the control of a Kaibel column through model-predictive control (MPC) in 2010 due to its high complexity. Obviously, larger potential benefits, including capital and operation costs, can be gained with a KDWC than with conventional direct and indirect distillation sequences. , Furthermore, KDWC is the simplest physical structure in four-component mixture separation DWCs. DWCs with two partitioning walls (e.g., Agrawal column) exhibit significant advantages in energy saving; , however, their complicated topological structures greatly restrict their development and industrial implementation.…”

“…Obviously, larger potential benefits, including capital and operation costs, can be gained with a KDWC than with conventional direct and indirect distillation sequences. 37,38 Furthermore, KDWC is the simplest physical structure in fourcomponent mixture separation DWCs. DWCs with two partitioning walls (e.g., Agrawal column) exhibit significant advantages in energy saving; 8,10 however, their complicated topological structures greatly restrict their development and industrial implementation.…”

Comparing Composition Control Structures for Kaibel Distillation Columns

“…The former includes two sidestream products that are significantly coupled each other but the latter includes only one sidestream product; (3). Remixing effect is completely eliminated in the latter but still slightly existed in the former [11]. From the three differences above, it is not difficult to deduce a fact that the nonlinear degree of the Kaibel distillation column is higher than that of the conventional three-component DWDC.…”

Experimental and computational fluid dynamics modeling of double‐partition divided‐wall column for flow hydrodynamics and wall heat transfer characteristics

“…Previous studies have mainly focused on the steady‐state design over the dynamic control scheme, multiphase flow hydrodynamics, and heat transfer characteristics of DPDWC. Studies focused on the dynamic control structure, including composition control (CC), temperature control (TC), temperature‐composition control (TCC), asymmetrical temperature control (ATC), TDC, double temperature difference control (DTDC), pressure‐compensated temperature control (PTC), and remixing control structures, for single‐partition DWCs can serve as a guide for developing DPDWCs 20–40 . However, few studies have focused on the multiphase flow hydrodynamics and heat transfer characteristics of DPDWCs.…”