Slurry reactor design features

In slurry reactors, the catalyst particles are freely dispersed in the fluid phase (water) and consequently, the photocatalyst is fully integrated in the liquid mobile phase. The immobilized catalyst reactor design features a catalyst anchored to a fixed support, dispersed on the stationary phase (the catalyst-support system). 

Table V shows the salient features of several Fischer-Tropsch processes. Two of these—the powdered catalyst-oil slurry and the granular catalyst-hot gas recycle—have not been developed to a satisfactory level of operability. They are included to indicate the progress that has been made in process development. Such progress has been quite marked in increase of space-time yield (kilograms of C3+ per cubic meter of reaction space per hour) and concomitant simplification of reactor design. The increase in specific yield (grams of C3+ per cubic meter of inert-free synthesis gas) has been less striking, as only one operable process—the granular catalyst-internally cooled (by oil circulation) process—has exceeded the best specific yield of the Ruhrchemie cobalt catalyst, end-gas recycle process. The importance of a high specific yield when coal is used as raw material for synthesis-gas production is shown by the estimate that 60 to 70% of the total cost of the product is the cost of purified synthesis gas.

Of the reactors listed in Table 17.1, the four most important are the mechanically agitated slurry reactor (MASR), the bubble-column slurry reactor (BCSR), the loop-recycle slurry reactor (LRSR), and the trickle-bed reactor (TBR). The first three, sketched in Figure 17.5, are slurry reactors, whereas the fourth is a fixed-bed reactor. The features most relevant to a preliminary design of these reactors in organic synthesis and technology are briefly described here. 

The design of conventional biological reactors is very similar to those of gas-liquid, slurry, and polymerization reactors outlined in other chapters. As a matter of fact, biological reactors are the most versatile of all reactors, since such a reactor can carry two or three phases, the liquid can be Newtonian or non-Newtonian, the solids can be heavy or light, and the reaction mixture can be simple or complex. A biological reactor, however, carries certain distinct features ... 

An SBC is a vertical, tubular column in which a three-phase (gas-solid-liquid) mixture is used. The slurry phase consists of FT catalysts and FT wax. The syngas flows though the slurry phase in the form of bubbles, as shown in Figure 12.12. The effective heat and mass transfer, low intraparticle diffusion, low pressure drop, and design simplicity are important advantages of this type of reactor. However, considerable problems arise in separating the liquid-phase synthesis products from the catalyst. With their attractive features, the SBC reactors are receiving extensive investment in both R D and commercialization. The concept of SBC is not new. 

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