Reactor internals

One vital aspect for FBR performance is the internal hardware design (Alvarez et al., 2007b). Reactor internals are responsible for the efficient catalyst utilization and process operation by means of uniform volumetric and thermal reactant distribution across the catalyst bed, quenching performance, and fouling protection (Ouwerkerk et al., 1999). Inappropriate reactor internal design causes poor catalyst utilization due to maldistribution of reactants and deficient quenching performance. 

In terms of catalyst utilization, the most relevant reactor hardware is the distributor tray as it is responsible for the liquid distribution across the catalyst bed. 

Good internal performance Poor internal performance 

FIGURE 7.6 Hydroprocessing reactor internals. (—) Axial delta-r and ( ) radial delta-r. 

In general, traditional distributor designs such as sieve trays, chimney trays, and bubble cap trays are known for their poor performance, whereas state-of-the-art distributors facilitate complete irrigation of the catalyst bed (e.g.. Shell s HD tray, Tops0e s Vapor-Lift tray, Exxon s Spider Vortex technologies, Akzo Nobel s Duplex tray, and Fluor s Swirl Cap tray). 

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Directory of Nuclear Research Reactors, International Atomic Energy Agency, Vienna, Austria, 1989. 

Reactor Internals and Unit Hardware. Requirements for mixing feed components or separating products may determine minimum pilot unit size. If reactants caimot be premixed before they are passed into the reactor, the effectiveness of the inlet distributor in mixing the reactants can markedly affect reactor performance. This is especially tme for gases, multiple phases, or Hquid streams of greatly different kinematic viscosities. 

After exiting tlie riser, tlie catalyst enters the reactor. In modern FCC operations, the reactor serves two basic functions as a disengaging space for the separation of catalyst and vapor, and as the housing for the reactor-internal cyclone. 

The quality of the FCC feed also impacts coke buildup in the reactor internals and vapor line and fouling/coking of the main column circuit. The asphaltene or the resid content of the feed, if not converted in the riser, can contribute to this coking. 

A typical batch reactor (Figure 8.1) will be made of stainless steel or glass-lined steel. Stainless steel vessels have better heat transfer characteristics than their glass-lined counterparts and a wider array of reactor internals are available. Glass-lined vessels, on the other hand, can offer superior fouling or corrosion properties and are often used for reactions... 

The catalyst (0.15 g) was loaded into a quartz tube reactor (internal diameter = 4 mm). The catalyst was pretreated in nitrogen at 400°C. Simulated gasoline reformate was used for the activity test of the catalyst. The composition of the simulated reformate was 36 wt% H2, 17 wt% CO2, 28 wt% N2, 17 wt% H2O, 1 wt% CO, and air was added additionally as the oxidant. The total flow rate was maintained at 100 ml/min. The test was performed over the temperature range of 120 280°C at various flow rates of inlet air. 

Although it is unclear at present how the public authorities would react if micro reactors were largely employed for production purposes, it stands to reason that in principle faster approval could be achieved in this way Approval is often connected with assigning the equipment under consideration to certain reactor categories which typically are defined, among other features, by the reactor internal volume. 

OS 33] ]R 16h] ]P 25] For the nitration of single-ring aromatics in a capillary-flow reactor, internal circulation, exhibiting an inner downwards and an outer upwards flow, in the aqueous slug of a two-phase flow was simulated [94]. 

Except for the Zircaloy in the reactor core, the reactor internals are stainless steel or other common corrosion-resistant alloys. The reactor vessel is a pressure vessel with a single full-diameter removable head. The base material of the vessel is low alloy steel, which is clad on the... 

Total heat given out to the reactor internal exchangers is the sum of further reaction heat and also sensible heat in the reaction gases cooling from 972°C to 643°C. Reaction heat for this stage is reported in Ref. PT1 as 0.054 times the sensible heat. Average heat capacity for the reaction mixture in this temperature range is 1.27 kJ/(kg K). 

In the same manner as in hydrocracking (Dolbear, 1997), hydrogen is added at intermediate points in hydrodesulfurization reactors. This is important for control of reactor temperatures. The mechanical devices in the reactor, called reactor internals, which accomplish this step are very important to successful processes. If redistribution is not efficient, some areas of the catalyst bed will have more contact with the feedstock. This can lead to three levels of problems ... 

Small bubbles and flow uniformity are important for gas-liquid and gas-liquid-solid multiphase reactors. A reactor internal was designed and installed in an external-loop airlift reactor (EL-ALR) to enhance bubble breakup and flow redistribution and improve reactor performance. Hydrodynamic parameters, including local gas holdup, bubble rise velocity, bubble Sauter diameter and liquid velocity were measured. A radial maldistribution index was introduced to describe radial non-uniformity in the hydrodynamic parameters. The influence of the internal on this index was studied. Experimental results show that The effect of the internal is to make the radial profiles of the gas holdup, bubble rise velocity and liquid velocity radially uniform. The bubble Sauter diameter decreases and the bubble size distribution is narrower. With increasing distance away from the internal, the radial profiles change back to be similar to those before contact with it. The internal improves the flow behavior up to a distance of 1.4 m. 

Keywords Airlift reactor Internal Radial profile Gas holdup Bubble size Bubble breakup... 

The reactor internals, consisting of structured packings packed with catalyst particles, are also examples of arranged catalysts, e.g., the Sulzers Katapak-S type. 

F. Caccavale, M. Iamarino, F. Pieni, and V. Tufano. An adaptive controller-observer scheme for temperature control of non-chain reactions in batch reactors. International Journal of Adaptive Control and Signal Processing, 22 627-651, 2008. 

Fukada, S., Y. Edao, M. Terashita (2009), Chemical Heat Pump System Working at Exhaust Temperature of High-temperature Gas-cooled Reactor , International Journal of Hydrogen Energy, 34, 540-546. 

Since in a large diameter fluid bed, bubbles may bypass the catalyst, elaborate hydrodynamic studies are required to scale-up the reactor internals to accomplish the complete conversion of methanol. As mentioned earlier, essentially complete conversion of methanol is a process requirement otherwise, a costly distillation step must be added to recover unconverted methanol. 

Vertical Scale-Up of Fluid Bed. The fluid-bed process was first scaled up vertically from the 45 cm tall bench-scale reactor to the 760 cm tall 4 B/D reactor shown schematically in Figure 11. The 4 B/D reactor internal diameter was 10 cm. 

Figure lU. Examples of fluid-bed reactor internal baffles... 

Figure 5.28 Left DEMIS pilot reactor for propylene oxide formation at Degussa site, superposed by schematic on the reactor construction. Right assembly of the reactor internals (by courtesy ofWiley-VCH Verlag GmbH) [61].

The method to calculate the dimensions of the modular canister, or a set of modular canisters to be used, is to employ Equations 7.42 and 7.43 to calculate the maximum D0, and also the previously estimated operational parameters of the PFIEBR, that is, x 60s, and < 0.1 d, where, is the ion-exchanger particle diameter and d is the reactor internal diameter and our knowledge about the total cation-exchange capacity of the packed natural zeolite. 

The two parameters a and p may be expected to depend on reactor internals and the amount of agitation. 

A tubular reactor will likely deviate from plug flow in most practical cases, e.g., due to backmixing in the direction of flow, reactor internals, etc. A way of simulating axial backmixing is to represent the reactor volume as a series of n stirred tanks in series. The steady-state solution for a single ideal CSTR may be extended to find the effluent concentration after two ideal CSTRs and then to n ideal stages as... 

While some CO and hydrocarbon emissions did occur during startup, it seems likely that these could have been greatly reduced by insulating the reactor internally rather than externally. 

Reactor Internal Surface Unpolished Stainless Polished and Gold Coated Stainless... 

Selection of the laboratory reactor requires considerable attention. There is no such thing as a universal laboratory reactor. Nor should the laboratory reactor necessarily be a reduced replica of the envisioned industrial reactor. Figure 1 illustrates this point for ammonia synthesis. The industrial reactor (5) makes effective use of the heat of reaction, considering the non-isothermal behavior of the reaction. The reactor internals allow heat to exchange between reactants and products. The radial flow of reactants and products through the various catalyst beds minimizes the pressure drop. In the laboratory, intrinsic catalyst characterization is done with an isothermally operated plug flow microreactor (6). 

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