Packed reactors packing material

Reactor type Multiphase packed-bed reactor Gasket material Viton... 

The pyrolytic reforming reactor was a packed bed in a quartz tube reactor. Quartz was selected to reduce the effect of the reactor construction material on the hydrocarbon decomposition rate. ° The reactor was packed with 5.0 0.1 g of AC (Darco KB-B) or CB (BP2000) carbon-based catalyst. The reactor was heated electrically and operated at 850—950 °C, and the reactants had a residence time of 20—50 s, depending on the fuel. The reactor was tested with propane, natural gas, and gasoline as the fuels. Experiments showed that a flow of 80% hydrogen, with the remainder being methane, was produced for over 180 min of continuous operation.The carbon produced was fine particles that could be blown out... 

The equipment required to develop this type of sensor is very simple and resembles closely that used to implement ordinary liquid-solid separations in FI manifolds. The only difference lies in the replacement of the packed reactor located in the transport-reaction zone with a packed (usually photometric or fluorimetric) flow-cell accommodated in the detector. Whether the packing material is inert or active, it should meet the following requirements (a) its particle diameter should be large enough (< 80-100 fim) to avoid overpressure (b) it should be made of a material compatible with the nature of the integrated detection system e.g. almost transparent for absorbance measurements) and, (c) the retention/elution process should be fast enough to avoid kinetic problems. 

Industrial reactors for catalytic incineration of VOCs contain ceramic or another inert packing material on the boundaries of the catalyst bed [9, 26]. In such reactors, the temperature after the inert ceramic packing can be estimated by the almost linear expression... 

The holdup of a phase is usually defined as the volume of the phase per unit reactor volume. However, for a fixed-bed reactor, the gas and liquid holdups are often defined on the basis of void volume of the reactor. In a fixed-bed reactor, the liquid and sometimes gas holdups are divided into two parts dynamic holdup, which depends largely on the gas and liquid flow rates and the properties of the fluids and the packing material, and static holdup, which depends to a major extent on the nature of the packing (e.g., porosity of the packing) and the fluids properties. The relationships between the holdups of various phases and the system variables for a variety of three-phase reactors are discussed in Chaps. 6 through 9. 

The second reactor setup type is commonly referred to as a biofilm bioreactor. This reactor is filled with packing material onto which a microbial biofilm is allowed to develop and biomass retention is achieved without the need for special membranes. Selected examples of this second type of reactor are provided in Table 7. 

Upflow fixed bed reactors or submerged biofilters (SBF) have upward groundwater flow, the packing material is submerged under water and no bed expansion is obtained [45,94-97]. 

In fixed-bed reactor technologies, an important factor is the pressure drop over the catalyst bed. In order to minimize the mass transfer effects, knitted silica fiber catalysts having small diffusion distance (< 10 pm) and low pressure drop, were applied in this study. 10 layers (0.4 g) of the catalyst was placed in the reactor between stainless steel nets and glass beads were used as inert packing material. The catalyst layer thickness was 0.15 cm resulting in catalyst bed length of... 

Packed reactors usually consist of a length of tubing filled with a chemically active or Inert material. They have not been widely used in FIA so far as packing materials with large particle sizes give rise to Insurmountable irregularities in the flow, while small-sized particles result In increased re-... 

In conclusion, a few comments about the practical importance of heterogeneous-homogeneous reactions from kinetic viewpoint. Usually industrial reactors have a relatively large free volume and the packing material is also present in addition to the catalyst. If homogeneous reactions are beneficial for the overall process, then they will be retarded due to deactivation of radicals and the rate will be lower compared to laboratory reactors with more advantageous reactor geometries. 

Packed reactors are readily made from pieces of suitable tubing into which the solid material is placed and where, if necessary, at both ends a small tuft of glass wool, fine plastic grid, or frit is placed, to keep the packing material within the column. Typical column dimensions are 1-3... 

Gas chromatography is a separation technique based on the fact that different components in the mixture exhibit different average residence times due to interactions with the porons packing material. These interactions can be classified as intrapellet diffusion and the column operates similar to a packed catalytic tubular reactor. The important mass transfer mechanisms are convection and diffusion. Hence, it is important to calculate the mass transfer Peclet number that represents an order-of-magnitude ratio of these two mass transfer rate processes. Intrapellet diffusion governs residence times, and interpellet axial dispersion affects the degree to which the output curve is broadened. For axial dispersion in packed columns and packed catalytic tubular reactors. 

For a heterogeneous catalytic reaction in an ideal packed-bed reactor, the material balance is written for a differential mass of catalyst, dW. The basic equation for the conversion of the key reactant A is the same as for any type of reaction, or combination of reactions, including reversible reactions. For A B-l-CorA B-l-CorA-l-B C-l-D,... 

The so-called single bead pearl string reactor first described by Reijn [10], and other packed reactors using inert packing materials are also shown to be effective as mixing reactors [4]. However they are more difficult to produce and less flexible than the knitted or knotted reactors, and, perhaps for this reason, are not used as broadly. 

Figure 9.1 Packed bed reactor internals (1) vessel, (2) packed material, (3) support plate, (4) liquid distributor, (5) gas input, (6) gas output, (7) liquid input, and (8) liquid output (Kolev, 2006).

Homogeneous bulk ATRP of methyl methacrylate homopolymer and block copolymers can be achieved with some success in a continuous packed-bed tubular reactor using a supported catalyst [73-75]. The metal catalyst can be adsorbed on the silica gel column packing material instead of dissolving the catalyst in the bulk of the reaction medium. Some control can be achieved, but it is not as effective as more typical reactions using soluble catalysts. This is typical of ATRP systems that use supported catalysts and is attributed to inefficient reaction of the propagating radicals with the supported deactivator [76]. Also, it has been speculated that the activation-deactivation reaction does not actually occur at the supported catalyst site, but rather occurs with a trace amount of free catalyst that is present in the system [77]. 

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