Flow reactor configuration

Most of today s distillate HDS processes consist of fixed-bed, down-flow reactors configured in a manner similar to that shown in Fig. 8 (7). It should be noted that hydrogen is used in excess and is recirculated after scrubbing out the H2S byproduct. Care must be used in the scrubbing operation as it is necessary to maintain a low but optimum level of H2S in the recycle stream to maintain catalyst stability and activity. The consequence of this H2S requirement when hydrotreating PASCs to extinction is discussed in more detail in later sections, but at this point it should be mentioned that H2S is a strong inhibitor of HDS for PASCs. 

Figure 1. Schematic of laser vaporization source/fast-flow reactor configuration currently employed in our laboratory.

Figure 16.2 Four ideal flow reactor configurations.

Multiphase Reactors. The overwhelming majority of industrial reactors are multiphase reactors. Some important reactor configurations are illustrated in Figures 3 and 4. The names presented are often employed, but are not the only ones used. The presence of more than one phase, whether or not it is flowing, confounds analyses of reactors and increases the multiplicity of reactor configurations. Gases, Hquids, and soHds each flow in characteristic fashions, either dispersed in other phases or separately. Flow patterns in these reactors are complex and phases rarely exhibit idealized plug-flow or weU-stirred flow behavior. 

Fig ure 10-12a. The configuration of this radial fixed-flow reactor provides scope for investigating proposed performance-enhancing modifications. 

Another important challenge is to enhance the reliability of the design and scale up of multi-phase reactors, such as fluidized bed reactors and bubble-colunms. The design uncertainty caused by the complex flow in these reactors has often led to the choice of a reactor configuration that is more reliable but less efficient. An example is Mobil use a packed-bed reactor for the methanol to gasoline process in New Zealand, even though a... 

Figure 4.1 Flow scheme of a plant comprising an electrothermal tubing-based micro reactor configured for ethylene polymerization [1],...

The shape of the instantaneous yield curve determines the optimum reactor configuration and flow pattern for a particular reaction network. For cases where the instantaneous yield increases continuously with increasing reactant concentration, the optimum reactor configuration from a product selectivity viewpoint is a... 

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