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Refinery Reactors
Published in James G. Speight, Refinery Feedstocks, 2020
The most familiar form of the continuous reactor of this type is the continuous stirred-tank reactor (CSTR) (Figure 8.1), which is essentially a batch reactor used in a continuous flow. In fact, the reactor is better described as a batch reactor equipped with an impeller or other mixing device to provide efficient mixing. In chemical engineering the name continuous stirred-tank reactor is often used to refer to an idealized agitated-tank reactor used to model operation variables required to attain a specified output. In flow chemistry, a continuous stirred-tank reactor equipped with features to continuously feed and exhaust reactants is an example of a mechanically mixed flow reactor. A continuous stirred-tank reactor often refers to a model used to estimate the key unit operation variables when using a continuous agitated-tank reactor to reach a specified output. The behavior of a continuous agitated-tank reactor is often approximated or modeled by that of a continuous stirred-tank reactor. All calculations performed with continuous ideally stirred-tank reactors assume perfect mixing. The disadvantage with a single-stage continuous stirred-tank reactor is that it can be relatively wasteful on products during start-up and shut-down. The reactants are also added to a mixture that is rich in product. For some types of processes, this can have an impact on quality and yield. These problems are managed by using multistage continuous stirred-tank reactors. At the large scale, conventional batch reactors can be used for the continuous stirred-tank reactor stages.
Small Molecules: Process Intensification and Continuous Synthesis
Published in Anthony J. Hickey, Sandro R.P. da Rocha, Pharmaceutical Inhalation Aerosol Technology, 2019
Figure 7.7 outlines some of the categories of chemical reactions which can be conducted on laboratory scale, but are generally discouraged in a multipurpose pilot plant facility (company dependent). Continuous flow chemistry has been widely used in the petroleum industry due to the large volumes, stable and well understood volume requirements, a cost constrained environment, and a liquid product output (i.e. pipe friendly). While the pharma industry has its own set of cost constraints, many of the volume and economic drivers present in the petroleum industry do not exist in the pharma industry, and therefore there has been little drive to implement continuous flow chemistry. Nevertheless, continuous chemistry offers scientific and engineering drivers (i.e. process intensification) which are common to both industries, such as control of product quality, ability to scale-out by building additional modules, ability to safely concentrate reactions, ability to conduct highly exothermic chemistry, and ability to access chemistries which are challenging to operate in batch (photochemistry, halogenation by molecular halides, nitrations, etc.). Traditionally, continuous flow chemistry has been the purview of chemical engineers in the petroleum industry, and therefore academic engineering curricula and research have developed to support the industry. However, both chemists and chemical engineers are now exploring the ability of flow chemistry to be used in the context of pharmaceutical production due to the scientific and regulatory opportunities outlined above.28
Green Chemistry and Green Catalysts
Published in Ahindra Nag, Greener Synthesis of Organic Compounds, Drugs and Natural Products, 2022
Ahindra Nag, Himadri Sekhar Maity
Flow chemistry reactions are continuous flow reactions where reactant components are pumped in a tube or pipe at a controlled temperature to complete the reactions.33 The process is robust, control and stability inherent in steady state operation of continuous process. Pharmaceutical industries generally rely on manufacturing of pharmaceutical ingredients in multipurpose batch or semi-batch reactors, but in the present system that interest among researchers is arising toward continuous flow manufacturing of organic molecules, including highly functionalized and chiral compounds. Automated flow-based techniques enable optimization and determination of the kinetics of chemical mechanisms at the milligram scale. The advantages of the reactions are as follows:
Mass and heat transfer enhancement by a novel mixer with triangular-notched rectangular baffles for continuous flow chemical process
Published in Numerical Heat Transfer, Part A: Applications, 2023
Pengjie Yu, Shuangfei Zhao, Yingying Nie, Yimin Wei, Runze Hu, Wei He, Ning Zhu, Yuguang Li, Dong Ji, Kai Guo
Continuous flow chemistry refers to the chemical reaction process carried out in the state of continuous flow. Due to the advantages of high efficiency, good safety, and low environmental pollution, continuous flow technology has become one of the important technologies affecting the development of the chemical industry [1–3]. As a kind of continuous flow reactor, microreactor has excellent mass transfer and heat transfer performance [4–7]. Thus, it has been widely used in various organic synthesis, nanoparticle synthesis, and catalytic reactions [8–10]. However, due to the small channel size of the microreactor, which limits the flow rate, its industrial application is still a challenge [11]. Additionally, low mass and heat transfer efficiency usually lead to the low selectivity of organic synthesis reaction and the wide molecular weight or particle size distribution of materials [12–14]. Therefore, it is very important to design mixers with high mass and heat transfer efficiency and high treatment capacity at the same time.
Effect of channel dimension on biodiesel yield in millireactors produced by stereolithography
Published in International Journal of Green Energy, 2021
Marija Lukić, Domagoj Vrsaljko
One way of process intensification is moving from traditional batch processes to continuous (Diab and Gerogiorgis 2017). The field of chemistry that deals with the mentioned area is flow chemistry (Movsisyan et al. 2016) and refers to chemical reactions in flow systems, most often in microreactors (Nmethn-Svg and Benke 2014). In the last decade applications of microreactor devices expanded rapidly, but their wider application in industry remains limited by their small flow of product and still relatively complicated methods of production. The field of microreactor technology has grown out of its primary purpose – simple flow reactors, and consequently made an impact on new technologies and production techniques, and thus helped create new keywords like MEMS, BioMEMS, Lab-On-Chip, μTAS (Micro Total Analysis Systems). Because of that, microreactors have become synonymous to advanced microfluidic devices used in a variety of cutting-edge applications (Suryawanshi et al. 2018).
Flow reactor synthesis of unsymmetrically substituted p-terphenyls using sequentially selective Suzuki cross-coupling protocols
Published in Green Chemistry Letters and Reviews, 2019
Shahid A. Kazi, Eva M. Campi, Milton T. W. Hearn
In recent years, flow chemistry has emerged as an enabling technology, allowing access to novel and more sustainable manufacturing processes (29). Where necessary, reactions can be performed under high temperature and pressure conditions, often above the boiling point of the carrier solvents used. Favourable attributes also include excellent control over reaction parameters, i.e. more efficient control of local heating and temperature profiles during the reaction, leading to enhanced mass transfer, thereby often resulting in improved selectivity and yield (30,31). This approach, in principle, also permits the integration of several steps into a single streamlined process, thus potentially shortening the synthesis time for structurally more complex compounds (32). Continuous manufacturing with flow reactors can also contribute to the adoption of more sustainable green chemical practices, with hazardous compounds better contained and, in many cases, the amounts of these and other chemicals, including waste, significantly reduced (33).