Reactor dimensions

The work reported here is part of a continuing program on the emulsion polymerization of styrene in a tubular reactor. It is now evident that the reactor construction is of primary importance in avoiding the problem of reactor plugging. The plugging is associated with a wall effect so that both the reactor dimensions and the nature of the wall surface are important. 

Proposing a Methodology for Micro-reactor Dimensioning and Layout... 

Table 1.6 Characteristic quantities to be considered for micro-reactor dimensioning and layout. Steps 1, 2, and 3 correspond to the dimensioning of the channel diameter, channel length and channel walls, respectively. Symbols appearing in these expressions not previously defined are the effective axial diffusion coefficient D, the density thermal conductivity specific heat Cp and total cross-sectional area S, of the wall material, the total process gas mass flow m, and the reactant concentration Cg [114].

The mass velocity G will be constant over the reactor length, and this quantity may be determined from the specified production rate and the reactor dimensions. To produce 50 tons/day of 100% H2S04, the number of pound moles of S02 that must be oxidized per second is ... 

To estimate costs for the liquid-liquid biphasic hydroformylation using ionic liquids, a process was designed for the production of 100,000 tons per year of nonanal. The use of ionic liquids in hydroformylation catalysis is a fairly new technology and exact kinetic data are scarce, thus the TOFs reported for the Rh-sulfoxantphos system [80] have been used to determine catalyst inventory and reactor dimensions. In a similar way the plant design for the SILP process for a production capacity of 100,000 tons per year of butanal has been derived based on preliminary literature results [68]. The process flow sheets for both process variations are shown in Figures 7.12 and 7.13. 

The reactor dimensions and operating temperatures were the same. 

The specific surface area of an industrial-sized continuous stirred tank reactor (CSTR) can be calculated from the reactor dimensions. However, it is difficult to estimate the effect of the formation of bubbles and of the stirrer-induced vortex at low melt viscosity. The calculation of the characteristic length of diffusion in a high-viscosity finishing reactor with devices for the generation of thin films with respective high specific surface areas is more complex. 

Fig. 1. Detail of reaction zone of the metal-atom reactor. Suitable reactor dimensions are 15-18 cm diameter, 5 mm wall thickness and 36-46 cm depth. The water-cooled electrodes are 7.5 cm apart. The central substrate inlet tube, a 6 mm od Pyrex slightly constricted at the end, extends 5 cm below the liquid nitrogen level. A 14 mm od Pyrex tube which serves as a substrate deflector is positioned 5 cm below the inlet nozzle and is suspended horizontally between the electrodes. A built-in Pyrex syphon tube extends to the bottom of the reactor for the removal of air sensitive products under an inert atmosphere.

Explore the design space. Assume that the reactor dimensions and temperatures are fixed. However, the flow rates and the flow direction need to be established. 

With a single passage, approximately 20 - 40% of the ethylene introduced is converted into polyethylene in the reactor. On the basis of current reactor dimensions, this corresponds to a LDPE production of 100,000 - 300,000 t/a per reactor. 

The flow phenomena in TBR are not easy to predict, because of the large number of variables such a bed porosity, size and shape of the catalyst, viscosity, density, interfacial tension, flowrates, and reactor dimensions. 

Regenerator dimensions Reactor dimensions Catalyst retention in reactor Catalyst retention in generator API of raw oil feed Reactor pressure Regenerator pressure Average particle size Pore volume of catalyst Apparent bulk density Catalyst surface area... 

A detailed mechanistic investigation of the explosion limits revealed [59] that the first and the third explosion limits of the reaction are dependent on the reactor dimensions (see Figure 2.27). The first explosion limit is reached when the mean free path of the molecules becomes smaller than the reactor dimensions, which... 

Micro structured reactors will not only increase reactor compactness and reduce the size of sometimes expensive samples but will also allow a thorough fluidic description of the flow in the reactor. The mechanism, which assists here, is the laminar-flow regime, which develops owing to the small reactor dimensions. 

The nonideal behavior also depends on reactor dimensions thus scale-up methods are sketched, in order to face the problems deriving from the industrial scale of those reactors. 

In general, on increasing the reactor volume, the required heat transfer surface increases faster than S3 this effect is enhanced by the decrease of the heat transfer coefficient. This prescription cannot be obeyed by the lateral surface of the reactor (which increases as S2) so that an internal or external additional heat exchange surface, whose dimensions can be fixed independently from the reactor dimensions, must be provided. 

When considering the use of microreaction technology, from the perspective of high-throughput organic synthesis, the main benefit that this technique offers is increased reaction control, which in itself affords many practical advantages to the user. As a result of the small reactor dimensions, rapid mixing of reactants, and an even temperature distribution are observed, which not only increase the uniformity of reaction conditions, but also afford increased reaction safety, selectivity, reproducibility, and efficiency when compared to conventional batch reactors where hot spot formation can lead to the formation of by-products and the risk of thermal runaway. 

The control that is needed to achieve good reproducibility of results from one laboratory to another extends from the composition and structure of the catalyst and the conditions of its pretreatment to the apparatus in which this, and the ensuing catalytic reaction, are performed. Experience teaches that factors such as reactor dimensions and the material of its construction are critical for reproducibility, especially in the case of exothermic reactions, as shown in Section 11.1.3.1. It is of course supposed that, when comparison between different pieces of equipment is attempted, all other controllable factors such as temperature, reactant pressures, purification of reactants, etc. are held constant to within whatever limits are practicable. 

Reactor Dimensions. Borosilicate glass tube, 10-mm. i.d., with 6-mm. o.d. thermocouple well down the center. The catalyst was supported on a sintered-glass disk. The empty tube was tested for catalytic activity and found inactive towards thiophene at temperatures up to 550° C. 

The limiting values for Q and (f> can be calculated from geometrical considerations of the lamps and reactor dimensions and their relative positions. The final result is... 

Particle diameter and reactor dimensions have a marked influence on the concentration distribution of the solid particles. 

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