Semicontinuous Thermal Separation Systems

Adams, Thomas A.; Pascall, Alicia

doi:10.1002/ceat.201200048

Cited by 21 publications

(18 citation statements)

References 22 publications

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“…In the work of Adams, intermittent flow is termed semicontinuous operation. 29 Adams describes it as a forced cyclic process, in which there are no steady states. He explains that it is possible to achieve multiple separation steps and high reaction conversion using fewer vessels than would be required in a truly continuous operation.…”

Section: ■ Introductionmentioning

confidence: 99%

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Development of an Intermittent-Flow Enantioselective Aza-Henry Reaction Using an Arylnitromethane and Homogeneous Brønsted Acid–Base Catalyst with Recycle

Tsukanov

Johnson

May

et al. 2016

Org. Process Res. Dev.

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A stereoselective aza-Henry reaction between an arylnitromethane and Boc-protected aryl aldimine using a homogeneous Brønsted acid–base catalyst was translated from batch format to an automated intermittent-flow process. This work demonstrates the advantages of a novel intermittent-flow setup with product crystallization and slow reagent addition which is not amenable to the standard continuous equipment: plug flow tube reactor (PFR) or continuous stirred tank reactor (CSTR). A significant benefit of this strategy was the integration of an organocatalytic enantioselective reaction with straightforward product separation, including recycle of the catalyst, resulting in increased intensity of the process by maintaining high catalyst concentration in the reactor. A continuous campaign confirmed that these conditions could effectively provide high throughput of material using an automated system while maintaining high selectivity, thereby addressing nitroalkane safety and minimizing catalyst usage.

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Section: ■ Introductionmentioning

confidence: 99%

“…The intermittent flow approach has been taken by other researchers. In the work of Adams, intermittent flow is termed semicontinuous operation . Adams describes it as a forced cyclic process, in which there are no steady states.…”

Section: Introductionmentioning

confidence: 99%

Development of an Intermittent-Flow Enantioselective Aza-Henry Reaction Using an Arylnitromethane and Homogeneous Brønsted Acid–Base Catalyst with Recycle

Tsukanov

Johnson

May

et al. 2016

Org. Process Res. Dev.

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“…Moreover, they proposed an efficient model which was able to select the most suitable separation system and its operating parameters. Adams and Pascall 2 reviewed semicontinuous separation processes. In the review, an auxiliary storage tank called a middle vessel (MV) was placed in the process.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Behavior and Residence Time Distribution of Industrial‐Scale Bale Packings

et al. 2014

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The hydrodynamic behavior of bale packing was tested in a catalytic distillation column. Models and empirical equations for predicting pressure drop and dynamic liquid holdup were proposed and compared with experimental results. The examination of residence time distribution (RTD) relied on the pulse method and a conductivity meter which deduced the axial Péclet number, axial dispersion coefficient, and dynamic liquid holdup. The relations of dynamic liquid holdup obtained from gravimetric draining experiments and RTD studies were discussed with static and total liquid holdup. Potential impacts of the liquid distributor and conductivity cell were also assessed. The results prove that models and empirical equations fit well and are reliable in design and scale‐up.

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“…These states of the middle vessel can be classified into three modes of system operation, which are separating mode, discharging mode, and charging mode. 4 During all the three modes, the concentration of feed components changes continuously with time. Since the process is not self-regulating, a control subsystem is used to maintain the control outputs at the desired values.…”

Section: ■ Detailed Process Descriptionmentioning

confidence: 99%

“…In this article, however, the focus is on the semicontinuous distillation of zeotropic ternary mixtures, which requires two pieces of equipment for separations of ternary mixtures: a distillation column and a process vessel called the middle vessel, and a control system which drives the process. 4 The batches of feed to be distilled are fed periodically to the middle vessel, which in turn continually feeds the distillation column. Simultaneously, a side stream from the distillation column is continually recycled to the middle vessel.…”

Section: ■ Introductionmentioning

confidence: 99%

Finding Better Limit Cycles of Semicontinuous Distillation. 1. Back Stepping Design Methodology

Madabhushi

Adams

2019

Ind. Eng. Chem. Res.

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Semicontinuous ternary zeotropic distillation is a periodic process that is carried out in a single distillation column and a tightly integrated external middle vessel. In the state-of-the-art design procedure of this process, a continuous distillation process that separates the top and bottom products to the desired purity is used to generate an arbitrary initial state for simulating the dynamics of the semicontinuous distillation process. Although this method is useful in estimating the limit cycle, it was later found that the operation of the process in this limit cycle was economically suboptimal. In this study, a new algorithmic design procedure, called the back-stepping design methodology, is proposed to find better limit cycles for zeotropic ternary semicontinuous distillation using the aspenONE Engineering suite. The proposed methodology was applied to two different case studies using feed mixtures with different chemical components. A comparison with the current design procedure for the two case studies indicates that the new method outperforms the state-of-the-art by finding limit cycles that were 4−16% lower in separating cost, which was the chosen measure of cycle performance.

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Semicontinuous Thermal Separation Systems

Cited by 21 publications

References 22 publications

Development of an Intermittent-Flow Enantioselective Aza-Henry Reaction Using an Arylnitromethane and Homogeneous Brønsted Acid–Base Catalyst with Recycle

Development of an Intermittent-Flow Enantioselective Aza-Henry Reaction Using an Arylnitromethane and Homogeneous Brønsted Acid–Base Catalyst with Recycle

Hydrodynamic Behavior and Residence Time Distribution of Industrial‐Scale Bale Packings

Finding Better Limit Cycles of Semicontinuous Distillation. 1. Back Stepping Design Methodology

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