Laboratory reactors pilot scale

These methods hardly take spatial distributions of velocity field and chemical species or transient phenomena into account, although most chemical reactors are operated in the turbulent regime and/or a multiphase flow mode. As a result, yield and selectivity of commercial chemical reactors often deviate from the values at their laboratory or pilot-scale prototypes. Scale-up of many chemical reactors, in particular the multiphase types, is still surrounded by a fame of mystery indeed. Another problem relates to the occurrence of thermal runaways due to hot spots as a result of poor local mixing effects. 

The choice of appropriate reaction conditions is crucial for optimized performance in alkylation. The most important parameters are the reaction temperature, the feed alkane/alkene ratio, the alkene space velocity, the alkene feed composition, and the reactor design. Changing these parameters will induce similar effects for any alkylation catalyst, but the sensitivity to changes varies from catalyst to catalyst. Table II is a summary of the most important parameters employed in industrial operations for different acids. The values given for zeolites represent best estimates of data available from laboratory and pilot-scale experiments. 

The numbers for the liquid acids are taken from Refs. (12,23,221). As zeolites are not used in industrial alkylation process, the given values represent the judgment of the authors extracted from laboratory and pilot scale data obtained in a slurry reactor. 

Nonetheless, there are running plants at laboratory and pilot-scale levels at institutes/universities and industry where process control is already exerted. Usually this is done in a rather conventional fashion, e.g. using commercial pressure hold valves and temperature determination at the in- and outlets and process-specific concentration monitoring outside the micro reactor. For example, an analysis of the redox potential was used for process monitoring for continuous azo pigment production at Clariant (see Figure 4.68) [99],... 

The average total liquid holdup in a trickle bed reactor decreases with increasing bed depth in a low pressure laboratory or pilot scale column. However, for commercial use where there is a moderate to high pressure input, the holdup is essentially constant (Figure 5). 

Figure 4 Laboratory and pilot scale photocatalytic reactors. Keys (1) PCE + air, (2) air, (3) mass flowmeter, (4) air humidifier, (5) thermostatic bath, (6) heat exchanger, (7) thermohygrometer, (8) flat plate photoreactor, (9) sampling device, (10) recycle pump, (11) gas scrubber, (12) multiannular photocatalytic reactor.

Table 2 Laboratory and pilot scale reactor description and operating conditions... 

Fuller ME and Manning JF, Microbiological changes during bioremediation of explo-sives-contaminated soils in laboratory and pilot-scale bioslurry reactors, Biores. Technol., 91, 123, 2004. 

Micromixer-tube reactor plants have been employed both at laboratory and pilot-scale [30]. For initial process development, a triangular ( focusing ) interdigital micromixer was used (Fig. 6.18), while for the pilot scale-out a caterpillar mixer was connected to four tubes of different hydraulic diameter by a five-port valve. 

Mechanically stirred batch reactors are often used for the production of fine chemicals and pharmaceuticals. One might wonder why this is so. One important reason for the choice of this type of reactor is its widespread use in laboratory and pilot-scale research and development programs-the mechanically stirred batch reactor is, therefore, often the fii st reactor that comes to mind. Frequently, however, other types of reactor are preferable for reasons such as better reactant conversion, product selectivity, ease of catalyst separation, etc. 

Development and Design of Laboratory and Pilot Scale Reactors for Microwave-assisted Chemistry... 

By mid-1995, only 220 papers had been published on microwave-assisted organic chemistry [15]. Until then the vast majority of the papers had covered dry media reactions and for approximately the next five years this trend continued. By the turn of the 21st Century, however, the applicability of dedicated microwave reactors and associated chemistry had stimulated other researchers and encouraged commercial manufacturers to construct systems for laboratory and pilot-scale studies [13, 14]. 

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