Fixed-bed trickling

Reactors in which the solid catalyst particles remain in a fixed position relative to one another (fixed bed, trickle bed, and moving bed reactors). 

THREE-PHASE FIXED BEDS TRICKLE-BED AND PACKED BUBBLE-BED REACTORS... 

Three-Phase Fixed Beds Trickle-Bed and Packed Bubble-Bed Reactors... 

In connection with the engineering content of the book, a large number of reactors is analyzed two- and three-phase (slurry) agitated reactors (batch and continuous flow), two-and three-phase fixed beds (fixed beds, trickle beds, and packed bubble beds), three-phase (slurry) bubble columns, and two-phase fluidized beds. All these reactors are applicable to catalysis two-phase fixed and fluidized beds and agitated tank reactors concern adsorption and ion exchange as well. 

H2 conversion was also typically lower than total, ranging from 30 to 70%. A H2 recycle is thus necessary. Staged (sequential) addition of H2 to maintain a more uniform 02 H2 ratio in the reactor and avoid excess 02 has also been shown to improve performances. Batch-type autoclave or continuous fixed bed (trickle-bed) or stirred reactors have been used. Operations were typically under pressure in the 50-100 bar range, again with the exception of the cited CSIR patents. The reaction temperature ranged from 4 to 605 °C. Upon decreasing the temperature, H2 solubility increases, but the catalyst specific activity decreases. The productivity should thus pass through a maximum nevertheless this depends from case to case. Table 8.3 summarizes selected results from recent patents. 

The Residue Hydroconversion process (Figure 9-27) is a high-pressure fixed-bed trickle-flow hydrocatalytic process. The feedstock can be desalted, atmospheric, or vacuum residue. 

Industrially, hydrodesulfurization of oil fractions, like aU hydroprocessing, is carried out catalytically in a fixed bed trickle flow unit. The catalyst is stacked in a packed bed and gas (hydrogen) and liquid (oil) are fed downstream concurrently. The reactor operates in the trickle-flow regime, in which the catalyst pellets are fully wetted with the liquid and both gas and liquid flow along the external surface. 

Industrial catalytic reactors, on the other hand, cover different types such as fixed bed, trickle bed, moving bed, fluidized bed, slurry, and monolith. This set of reactors is schematically shown in Figure 8.3. The details of a fixed-bed reactor are shown in Figure 8.4. 

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