Small reactor systems

A new innovative approach to small reactor system design... 

Principle safety objectives for innovative small reactor system have been identified ... 

Significant benefits can also be realized from reduced operation and maintenance costs through remote qjeration. Thus, small reactor systems should be designed to niinimize the requirement for close and frequent supervision by skilled operators and maintenance personnel. Labour costs can be reduced by associating an < )erating aiKl maintenance labour force with several small plants in an efficient manner. 

Each heating technique has its advantages and disadvantages, and changing from one technique to another may involve significant changes in the process variables. The cold-waH reactor is most often used in small-size systems. The hot-waH reactor, by contrast, is most often used in large-volume production reactors. 

Also assume that the pilot- and full-scale vessels will operate at the same temperature. This means that A(o-out,bout, . )and/i/2 will be the same for the two vessels and that Equation (1.49) will have the same solution for provided that 7 is held constant during scaleup. Scaling with a constant value for the mean residence time is standard practice for reactors. If the scaleup succeeds in maintaining the CSTR-like environment, the large and small reactors will behave identically with respect to the reaction. Constant residence time means that the system inventory, pV, should also scale as S. The inventory scaleup factor is defined as... 

A parallel reactor system has an extra degree of freedom compared with a series system. The total volume and flow rate can be arbitrarily divided between the parallel elements. For reactors in series, only the volume can be divided since the two reactors must operate at the same flow rate. Despite this extra variable, there are no performance advantages compared with a single reactor that has the same total V and Q, provided the parallel reactors are at the same temperature. When significant amounts of heat must be transferred to or from the reactants, identical small reactors in parallel may be preferred because the desired operating temperature is easier to achieve. 

Many experimental results have been published, which deal with shear stress in biological systems. Most of them use laminar flow systems such as viscosimeters, flow channels or flasks and very small agitated vessels which are not relevant to technical reactor systems with fully developed turbulent flow. On the other hand the geometric and technical parameters are often not sufficiently described. Therefore it is not possible to explain the complex mechanism of force in bioreactors only on the basis of existing results from biological systems. 

This equation should generally valid for all particle systems and working conditions with (9p-9)/9 1, dp/qL< 6 and A/qL> 125... 250. The last condition of fully developed turbulent flow is very important. To small values A/qp which mostly corresponds to Reynolds numbers Re <10 (small reactors, higher viscosity s of media and small power input) leads to an distinct reduction of stress. That was observed by the investigations in 166] which were carried out with the... 

We have also tried the trapping reactor system, in which ammonia is trapped on the catalyst/adsorbent and microwave is irradiated intermittently. However, due to the small specific surface area and the small ammonia adsorption capacity on the employed CuO, the trapping system was not effective compared to the continuous irradiation. Further study should be made to develop a material having high ammonia adsorption capacity and high efficiency for microwave absorption. Supported CuO on high surface area material or preparation of high surface area CuO can be effective. 

Experiments were carried out in a pulse reactor system based on the TAP-2 reactor described by Cleaves et al. [3]. This consists of a small tubular reactor and a detector housed in a vacujun system pumped by a 1,500 Is" turbomolecular pump to a base pressure of... 

Release of from preoxidised 4% RhO /CeOj at temperatures > 473 K into a low pressure of Oxygen-18 enriched Oj was reported previously on the basis of measurements made with the recirculatory reactor system [8]. An analagous experiment in the present study, featuring a low pressure of Nj O in contact with preoxidised 4% RhO /CeOj while temperature was raised 300-500 K, likewise showed a small release of (together with Nj). However, Oj release was not observed when that sample was mildly prereduced nor when CeO was similarly tested. Preoxidised rhodia dispersed upon Ceria is thus seen to enhance the ease of release of O, at temperatures < 550 K. 

The principle of the perfectly-mixed stirred tank has been discussed previously in Sec. 1.2.2, and this provides essential building block for modelling applications. In this section, the concept is applied to tank type reactor systems and stagewise mass transfer applications, such that the resulting model equations often appear in the form of linked sets of first-order difference differential equations. Solution by digital simulation works well for small problems, in which the number of equations are relatively small and where the problem is not compounded by stiffness or by the need for iterative procedures. For these reasons, the dynamic modelling of the continuous distillation columns in this section is intended only as a demonstration of method, rather than as a realistic attempt at solution. For the solution of complex distillation problems, the reader is referred to commercial dynamic simulation packages. 

The scale-up from a small to a large plasma reactor system requires only linear extrapolations of power and gas flow rates. However, in practice, the change in reactor geometry may result in effects on plasma chemistry or physics that were unexpected, due to a lack of precise knowledge of the process. Fine tuning, or even coarse readjustment, is needed, and is mostly done empirically. 

In the segregated flow model the contents of the volume elements of the fluid do not mix with one another as they move through the reactor. Each element may be considered as a small closed system that moves through the reactor. The different systems spend varying amounts of time in the reactor, giving rise to the measured residence time distribution func-... 

Decolorization of azo dye R016 by immobilized cultures of I. lacteus was compared in three different reactor systems [59]. Different size of PuF was used for immobilization in reactors. Biomass concentration was reported to be 11.6, 8.3, and 4.9 g dw/L in Small Trickle Bed Reactor (STBR), Large Trickle Bed Reactor, and Rotating Disk Bioreactor, respectively. Decolorization rate was found high in STBR, where 90% decolorization rates were achieved after 3 days. Dye decolorization was highly efficient, but no direct relationship between the extracellular enzyme activities (laccase and MnP) and dye decolorization capacity was found. 

---