Industrial structured reactors

Felcht reports on Degussa s activities in cooperation with partners from academia and industry to develop innovative industrial-scale micro-structured reactors for making large-tonnage products by liquid- and gas-phase reactions [137]. The aim is to make the potential of micro reactors more widely available for a larger variety of processes, naturally with focus on Degussa s fine and specialty chemical productions. Also, the aim is to circumvent traditional problems of scale-up. 

There is not much to be said about the use of micro reactors for bulk chemicals and commodities. Worz et al. are so far the only ones who have disclosed their work on the potential of micro-structured reactors for the optimization of chemical processes performed on a large scale ofindustrial relevance [110,112,154,288-290]. This included a fast exothermic liquid/liquid two-phase reaction, which was used for the industrial production of a vitamin intermediate product, and a selective oxidation reaction for an intermediate, a substituted formaldehyde derivative. 

In this book the chemical plant is focused upon. Therefore, the present chapter emphasizes chemical reactors for the chemical process industry. But it should be made clear that structured packings and catalysts also have a large potential in consumer products. Chemical reactors form the heart of a (petro-)chemicals production plant. Given the large variety of plants it is no surprise that a wide variety of chemical reactors are used. Catalytic reactors can be roughly divided into random and structured reactors. It is useful to start with a summary of the major basic concerns (apart from high activity, selectivity, etc.) for catalytic reactors ... 

Wet chemical etching, which applies photo-resist for masking and usually iron chloride solution for etching, is a mature and automated technique industrially available for many applications. It is competitive for mass production and allows for a relatively wide range of channel depths from about 100 up to 600 pm and more, which covers the channel size usually applied in micro structured reactors for processing gases. 

The American consortium NeSSI [23] (New Sampling Sensor Initiative) is a CPAC-sponsored (Center for Process Analytical Chemistry) open initiative formed in 2000 to create a standard for process analysis. The object is to implement modular and smart process analytics. It also aims at the future integration of micro analytical devices and micro structured reactors. The concept is derived from the semiconductor industry and follows the ISA SP76 standard. Companies such as Parker-Hannifin, Kinetics and Swagelok are involved. Further information is also given on the web site [23],... 

Within the framework of a BMBF-funded project, five research institutes are developing a standardized system for the combination of micro structured devices and laboratory equipment [86-88], The idea is to integrate devices from many different suppliers to build up a complex chemical plant. This is actually a normal procedure in industrial plant engineering as the large variety of chemical apparatus cannot be delivered from just one supplier. However, this approach is not widely used in micro structured reactor plant technology. Here usually one supplier tries to cover the whole range of devices. 

Micro process technology still remains concentrated on laboratory applications. In the last 3 years, only a few applications have become known of industrial implementations. It is expected that more industrial micro structured reactor plants exist but the details are not published. Published examples exist from Merck [53], UOP, Degussa/Uhde and Clariant, but details were only available at a low level for confidentiality reasons. 

The methods and the expenditure of basic engineering for a complex process executed in a micro structured reactor plant cannot be distinguished from those for an industrial plant. A flow chart for a small-scale process indicates a similar complexity (Figure 4.84). 

Catalytic processes are an essential operation of large-scale processes in the chemical industry. Appropriate micro structured reactors offer an increase in efficiency compared with conventional reactors if a method can be found to integrate low-cost devices in industrial practise. Automated procedures will enable professional manufacturing of reactors with an acceptable cost/performance ratio. 

Adaptation of Industrial Online Processes to Micro Structured Reactor Manufacturing... 

Conventional reactor technologies such as fixed beds and slurry reactors suffer from serious drawbacks. Mass transfer resistance is the crucial factor in the scaleup of processes. Laboratory experiments are often carried out with catalyst particles with diameters clearly less than 1 mm, whereas industrial reactors typically operate with larger catalyst particles ranging from 1 mm to 1 cm. The scale dimensions are illustrated in Figure 9.1. Intrinsic kinetics is thus inevitably coupled to the modeling of mass transfer, as has been illustrated in previous chapters. Internal mass transfer limitations can be suppressed by decreasing the particle size, but the particle sizes in industrial processes cannot be diminished limitlessly, because this would lead to a tremendous increase in the pressiue drop. To overcome this problem, new innovations and structured reactors have been developed, such as catalytic packing element reactors, monoliths, and fiber structures. The aim of these innovations has... 

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