External reactor

Figure 7-7 Reactant concentration profiles in directionx, which is perpendicular to the flow direction z expected for flow over porous catalyst pellets in a packed bed or sluny reactor. External mass transfer and pore diffusion produce the reactant concentration profiles shown.

This endothermic reaction is driven by heating the reactor externally or by adding oxygen to the feed to provide the necessary energy by highly exothermic combustion reactions. A typical steam reformer operates at 15 to 30 atm and 850 to 900 C with a Ni/Al203 catalyst and a superficial contact time (based on the feed gases at STP,... 

Existing literature on the control of reactor-external heat-exchanger processes is relatively scarce, concerning mostly the implementation of linear (Ali and Alhumaizi 2000, Henderson and Cornejo 1989) and nonlinear (Dadebo et al. 1997) control structures on specific processes. These studies report several control challenges, including difficult tuning of PID and model-based controllers due to the ill-conditioning of the process model. 

Figure 7.14 Energy flows of different magnitudes in a reactor-external-heat-exchanger system.

On the basis of the arguments regarding the cause of the non-minimum-phase behavior of the reactor-external-heat-exchanger process, the term... 

This process produces higher H2 to CO ratio (3 1) synthesis gas. Energy is supplied to drive this endothermic reaction by heating the reactor externally or by other means. 

The first method is a sure way to expose the surface of powder uniformly if one pass is sufficient to achieve the surface modification, but it is not easy to recycle the substrate in the luminous gas phase in vacuum. Therefore, the main issue in this approach is how to repeat the interaction of surface with the luminous gas phase efficiently, which entirely depends on the flow dynamics of powders. Multiple-step operation requires multiple discharge systems or repeated operation. The generation of discharge is more or less the same as the conventional modes used in LCVD reactors. External radio frequency electrodes or coil with glass tube is the most... 

Figure 3.10 Rayonet photochemical reactor (external configuration). Reproduced by permission of Southern New England Ultra Violet Company...

The Buss loop reactor is a system to increase the dissolving of gas into a liquid which contains a dissolved chemical and a catalyst. Normally the reaction is first order and the reaction rate is dependent upon gas diffusion rate. An example is the hydrogenation of glucose to sorbitol. The rate of reaction and yield is increased as follows. The liquid is pumped from the bottom of the reactor, externally up to and through an eductor and discharged subsurface into the agitated vessel contents. The reason for its success is that a high velocity eductor mixes and shears a gas into very fine bubbles of very... 

A potential solution to the issue of limited penetration depth could be to add a microwave reactor externally to a large batch reactor and cycle the reaction mixture through a loop continuously. However, this is effectively using the conventional reactor as a reservoir while processing small quantities of reaction mixture in the microwave field and, overall, it offers no advantage. Another solution is to either process smaller volumes in batch mode or else use a continuous-flow micro-wave reactor. These are the options that most investigators of microwave scale-up have used. 

The success of an ISPR process does not depend only on the chosen separation technique but also on the configuration of the bioreactor/separation units and mode of operation. Previous reviews have shown the various possible modes of operation (continuous, batch) and the use of a separation unit outside of the reactor or separation techniques that act right inside the fermenter [19,22,31]. Freeman and coworkers introduced a classification scheme for ISPR process based on batch/continuous operation and internal (within the reactor)/external (outside the reactor) removal of the product [3]. 

Thus, reactor volume increases faster than reactor external surface area when scaling to commercial size. If we operate a small reactor iso-thermally, then increasing reactor volume moves the reactor toward adiabatic operation. 

We can determine when reactor volume equals reactor external surface area. Solving for L in the equation for Ax yields... 

The solids and gas feeding system is similar to the previous reactor. External electrical heaters are needed to initiate the batch reaction. Much more heat has to be removed when the reaction is proceeding than applies... 

DME synthesis unit-fixed-bed reactor External reactor diameter 0.0381 m... 

The LFR system provides for ambient pressure single-phase primary coolant natural circulation heat transport and removal of core power under all operational and postulated accident conditions. The high boiling temperature of the Pb coolant enables heat transport by natural circulation of the primary coolant at significantly higher temperatures than with traditional liquid metal cooled reactors. External natural convection driven passive air-cooling of the guard/containment vessel is always in effect and removes power at decay heat levels. 

Despite the negligible radiological consequences it was concluded fi om analysis of the event that in the next BN-type reactors external primary sodium pipework systems have to be excluded by arranging them inside the reactor vessel, or (if impossible) by providing complete jacketing in order to have two leak-tight protective barriers. 

Crystallizing, batch processing design calculations, 99-100 CSTR (continuous stirred tank reactor) external heat exchanger, 714 reactor performance, 706-712 single-phase transfer medium, 714 Cumene catalyst, replacing, 721-726 Cumene process feed section, troubleshooting, 784-787 Cumene reactor... 

Fig. 14-3. Initial critical inventories of in two-region, homogeneous, molten fluoride-salt reactors. External fuel v6lume, 339 ft .

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