Arrangement radial flow reactor

A critical feature of packed radial-flow reactors is the shape of the upper bed closure. A simple horizontal covering is not practicable since a gap through which unreacted gas can pass is then formed due to the unavoidable settling of the packing. The arrangement... 

In a CCR unit Figure 19 the hydrotreated feed mixes with recycle hydrogen and goes to series of adiabatic, radial-flow reactors arranged in a vertical stack. Catalyst flows down the stack, while the reaction fluids flow radially across the annular catalyst beds. The predominant reforming reactions are endothermic, so heaters are used between reactors to reheat the charge to reaction temperature. Flue gas from the fired heaters is typically used to generate steam. 

This is also a reversible, exothermic reaction carried out in various types of fixed-bed reactors, involving different arrangements for flow (axial or radial), and temperature adjustment see Figure 11.5. The traditional catalyst is promoted Fe, but more active Ru-based catalysts are finding use, despite the added... 

In Figure 21.1, the first division is with respect to flow arrangement. Traditionally, most fixed-bed reactors are operated with axial flow of fluid down the bed of solid particles. A more recent trend is to use radial flow, either outward, as depicted in Figure 21.1, or inward. In the case of styrene monomer production (reaction (D) in Section 21.1), the purpose is to reduce the pressure drop (-AP) by increasing the flow area for a given bed volume. We restrict attention to axial flow in this chapter. 

Figure 26. Alternative arrangements for autothermal reactor design with periodic flow reversal A) Radial-flow concept B) Multiple-bed arrangement...

Figure 3.1 Fixed-bed reactors. Schematic representation of several operating configurations and arrangements (a) Cylindrical with axial flow (a.l-single, a.2-multistage, a.3-multitubular) (b) cylindrical with radial flow (c) spherical reactor (c.l-axial and c2-radial flow).

Palma et al. [144] developed WGS reactors in the kilowatt scale, which allowed gradual addition of the reformate through porous sintered stainless steel tubes into ceramic foams (SiC/Al203) coated with noble metal-based catalyst. Different flow arrangements through the foams were investigated (Figure 14.21), which revealed better performance for radial flow. 

In order to understand the profile of the pressure fluctuation over the volumetric space inside the reactor, multipoint measurement is carried out in each run with five probes. The measuring points are arranged according to the coordinate system shown in Fig. 11.3, where the x-z plane is the impingement plane, x-y is the horizontal plane, and y-z the vertical plane the values of the coordinates are in mm. The flow inside the SCISR is considered to have an approximately axial symmetry. For convenience, part of the data are interrelated in a pillar coordinate system, and the radial coordinate, r, is determined by... 

In the Haldor Topsoe process several reactors are used, arranged in series. The heat of reaction is removed by intermediate coolers. The synthesis gas flows radially through the catalyst beds. 

The drawback of randomly packed microreactors is the high pressure drop. In multitubular micro fixed beds, each channel must be packed identically or supplementary flow resistances must be introduced to avoid flow maldistribution between the channels, which leads to a broad residence time distribution in the reactor system. Initial developments led to structured catalytic micro-beds based on fibrous materials [8-10]. This concept is based on a structured catalytic bed arranged with parallel filaments giving identical flow characteristics to multichannel microreactors. The channels formed by filaments have an equivalent hydraulic diameter in the range of a few microns ensuring laminar flow and short diffusion times in the radial direction [10]. 

A concurrent downward flow circulating fluidized bed, or a downer, is a new alternative flow arrangement for a high-velocity system. A downer reactor system has similar system configurations to a riser reactor system except that both the gas and the solid particles flow downward. Concurrent downward flow of particles and gas reduces the residence time of solid particles because the downward flow is in the same direction as gravity. More uniform radial gas and solids flow than those in a riser can be achieved. The downer leads to more uniform contact time between the gas and solids. With these advantages, downer reactors have been proposed for processes such as fluid catalytic cracking, which requires short contact time and uniform gas and solids residence time distributions. 

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