Available online at www.sciencedirect.com
Procedia Engineering 42 (2012) 1214 – 1218
20th International Congress of Chemical and Process Engineering CHISA 2012 25 – 29 August 2012, Prague, Czech Republic
Modular microstructured reactors with integrated platform concept N. Kockmann a* TU Dortmund, BCI, Apparatedesign, Emil-Figge-Str. 68, D-44227 Dortmund, Germany
Abstract Microstructured reactors have found their role in laboratories for analytical and chemical synthesis purposes. To bring the lab results into production, the process has to be scaled up for higher throughput. A modular setup of the process steps such as heat exchange, mixing, or sufficient residence time under controlled process conditions is very helpful during scale up and for rapid process development. The platform concept of devices with similar flow rates and process conditions such as temperature, pressure or chemical resistivity on the same level gives a robust framework for consistent scale up. Some examples of modular equipment and their application also from industrial experience will explain this strategy and give hints for further development.
© 2012 Published by Elsevier Ltd. Selection under responsibility of the Congress Scientific Committee (Petr Kluson) Keywords: Modular process equipment; scale-up concept, microreactor, process development; small-scale production
1. Introduction Since nearly two decades, the concept of Process Intensification (PI) is applied in process chemical research and development as well as in production [1]. A key concept of PI is to treat molecules in an optimal way during the entire process from contacting on the molecular length scale over energy transfer with activation and removal to separation and formulation of the product [2]. To achieve this ambitious goal unit operations can be replaced by unit functions and functional modules to find a basic route of a chemical process [3]. It is widely accepted that microreactors play an integral part of process
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1877-7058 © 2012 Published by Elsevier Ltd. doi:10.1016/j.proeng.2012.07.513
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intensification. They have found their role in laboratories for analytical and chemical synthesis purposes in the area of flow-chemistry. The so-called Lab-on-Chip devices produce good results for the synthesis of new chemical products in various applications. Physical and chemical parameters can be determined in small devices with low consumption of precious materials from fine chemistry and pharmaceutical development [4]. There are many providers for flow chemistry systems; a good overview can be found in book of Wiles and Watts [5]. Typical characteristics of these continuous-flow devices and processes are short mixing time, excellent heat transfer and controlled residence time with small internal hold-up [6,7]. To bring the lab results into production, this contribution describes a modular reactor and continuousflow plant setup. Different unit function can be realized in a flexible plant configuration for various process conditions. The modular equipment setup is assisted by an integrated platform concept for consistent scale-up and early small scale production campaigns. 2. Modular reactor and plant setup Modules can be defined in different ways, which depend also on the application area. Here, a module represents a certain process step or unit function and can be combined with other modules in series or in parallel setup. The example of the Lonza FlowPlateTM reactor shows modularity on two levels [8]. The reactors can be coupled as module to pumps, capillaries for heat exchange and residence time or extraction columns. The reactor itself consists of several plates, which are connected in series with different functionality: heating and cooling, contacting and mixing as well as controlled residence time. In one single rack, all the plates up to 8 are hold on the same temperature level. The reactor plates are made from Hastelloy C22 for high chemical resistance. The reactor setup follows the reaction characteristics, especially the typical time scale for complete conversion, see Fig. 1. Fast mixing is necessary for rapid reactions shorter than one second. The modular plate arrangement in series is very helpful for reactions in the range of several seconds to minutes, where more plates can be added to provide sufficient residence time under controlled temperature conditions. Additionally, a modular setup is beneficial for fast and flexible process development to find optimal conditions for mixing and residence time.
Fig. 1. Lonza modular system according characteristic reaction time [8]
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This internal modularity can be extended by external tube modules for preheating and –cooling as well as for longer residence time. There are already some suppliers on the market for external modules along the process path. The Lonza FlowPlateTM lab reactor can be integrated in the Ehrfeld BTS GmbH modular microreactor system MMRS with several functionalities including sensing and photoreactions. Due to similar channel geometries, the chemical process can be directly scaled up from the Lonza FlowPlate TM lab reactor to the larger plate reactors with higher volumetric flow rate [9]. Other suppliers such as Corning SA [10] and Alfa Laval Inc. [11] offer comparable plate reactors from different materials and with variable size adjusted to the residence time, the volumetric flow rate, and production size. Other examples can be found at IMM GmbH with the StarLam reactor [12] or at Chemtrix BV with their Labtrix and Kiloflow system [13]. The latter includes also syringe pumps for continuous medium supply, sensors and analytical systems. A modular setup of the process steps such as pre-heating or cooling, mixing, and sufficient residence time under controlled process conditions is very helpful during scale up. The combination of various modules with different functions in process direction to a complete plant is called horizontal integration. The vertical line of modules follows the scale-up of the plant with higher throughput and production rate. This is called the platform concept with different levels, where all devices have similar characteristics of throughput (mL/min), pressure and temperature range, as well as chemical resistance. The company Microinnova GmbH adds different modules and equipment from various suppliers to a consistent concept, following the horizontal and vertical integration. The latter can be found in the S-class with flow rates from 1 to 10L/h and M-class with 10-100L/h. 3. Platform concept The platform concept of devices for similar flow rates and process conditions such as temperature, pressure or chemical resistivity on the same platform level gives a framework for efficient and rapid process development and consistent scale up into production environment. In the lab, the modules such as pumps and reactors are adjusted in flow rate, temperature, pressure, and chemical resistivity. Modules for low temperature vary from those for high temperature. Similarly, modules for high pressure differ from low pressure equipment. Often, the modules are “overdesigned” for the current process due to the wide variety of possible chemical and physical systems processed in the lab. After successful testing and evaluation of a production process in the lab, the process and the modules have to be scaled up to get a higher throughput and larger product quantity. In Fig. 2 the flow rate of the modules, here a tubular reactor, is displayed over the campaign size (amount of processed medium) for a certain campaign time. The lowest horizontal bar represents a tubular reactor with a nominal flow rate of 30mL/min. The vertical bar indicates 20 to 200% of the nominal performance in 1 minute. The +-marks indicate the throughput after 1, 8, 24, and 168h (7days) meaning a processed volume of more than 300L in one week. The amount of product is determined by its concentration in the solution. The thin line describes the performance of the tubular reactor with 200% performance. The second thick line represents a tubular reactor with a nominal performance of 0.3L/min meaning more than 140t processed fluid in 8000h. The diagonal lines connect the different reactors for equal operation times. The larger reactors with 10L/min and 1m3/min, respectively, are also displayed, which are reaching into larger production capacities up to 0.5Mio tons per year. With these flow rates and production capacities, not only the reactors are characterized, but also the pumps, tubes, heat exchangers, and work-up and separation units. Such platform systems can be found in other industries such as automotive [14] or industrial gases with small and medium size, cryogenic nitrogen generators [15].
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Fig. 2. Platform concept and scale-up of tubular reactors with examples of Lonza FlowPlateTM reactor and Ehrfeld BTS GmbH Miprowa devices. The process time is the dominant factor for high production rates
The above described, consistent platform levels consist of pumps, heat exchangers, mixers, residence time, work up units such as distillation, extraction or membrane devices and facilitate the scale up of chemical processes. The successful lab synthesis can rapidly be transformed into a production process for small and medium scale amounts typically found in fine chemistry and pharmaceutical industry. 4. Conclusion The modular setup of process equipment already in the laboratory enables the investigation of chemical processes and unit steps for intensified and consistent process development. The modules are often related to existing equipment and allow for a versatile plant configuration. The scale-up of the lab results follow the platform concept with different levels of volumetric flow rate (module size), temperature, pressure, and chemical resistivity. The same modules have similar characteristics on different platform levels and minimize the risk of process scale-up to production. The goal of this concept is the extensive process development and already detail engineering in the lab phase of process design. This enables a rapid market supply of small and medium amount of chemical products. Acknowledgements The author wants to acknowledge the help and discussion of his former colleagues at Lonza, especially D.M. Roberge, W. Quittmann, and M. Gottsponer.
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