Slurry reactors design

Fox, JM., Degen, B.D., Slurry Reactor Design Studies, Topical Report, Reactor Selection Criteria, US Department of Commerce, National Technical Information Service, USA (1990)... 

Slurry Reactor Design In the previous material we diseussed the transport and reaction steps and developed an equation for the overall resistance. A rearrangement of Equation (12-81) gives... 

Example R12-2 Determining the Controlling Resistance D. Slurry Reactor Design... 

Example R12-3 Slurry Reactor Design R12.2, Trickle Bed Reactors A. Fundamentals... 

Effect of axial dispersion in the liquid and the solid phase Where effects of axial dispersion of the gas phase can usually be neglected in slurry reactor design, the effects of mixing in the... 

Recent advances in Eischer-Tropsch technology at Sasol include the demonstration of the slurry-bed Eischer-Tropsch process and the new generation Sasol Advanced Synthol (SAS) Reactor, which is a classical fluidized-bed reactor design. The slurry-bed reactor is considered a superior alternative to the Arge tubular fixed-bed reactor. Commercial implementation of a slurry-bed design requires development of efficient catalyst separation techniques. Sasol has developed proprietary technology that provides satisfactory separation of wax and soHd catalyst, and a commercial-scale reactor is being commissioned in the first half of 1993. 

Continuous slurry reactors are generally either of one of two designs. One type uses a reactor loop, generally known as a Buss loop design the other is a co-current hydrogen/fatty acid/catalyst system mainly marketed by Lurgi. Continuous slurry reactors are more popular in Europe, Asia, and South America than in the United States. 

Mass transfer across the liquid-solid interface in mechanically agitated liquids containing suspended solid particles has been the subject of much research, and the data obtained for these systems are probably to some extent applicable to systems containing, in addition, a dispersed gas phase. Liquid-solid mass transfer in such systems has apparently not been studied separately. Recently published studies include papers by Calderbank and Jones (C3), Barker and Treybal (B5), Harriott (H4), and Marangozis and Johnson (M3, M4). Satterfield and Sherwood (S2) have reviewed this subject with specific reference to applications in slurry-reactor analysis and design. 

The reaction r = occurs on the external surface of a sphere of diameter D suspended in a stagnant fluid in which fhe diffusion coefficient of the reactant is Da- Find the total rate of the reaction in terms of these quantities. How does the rate depend on particle diameter How would this influence fhe design of a slurry reactor with this catalyst ... 

One example of this type of reactor is in the synthesis of catalyst powders and pellets by growing porous soHd oxides from supersaturated solution. Here the growth conditions control the porosity and pore diameter and tortuosity, factors that we have seen are crucial in designing optimal catalysts for packed bed, fluidized bed, or slurry reactors. 

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.

The treatment of PAH-contaminated soil in a reactor environment is basically limited to the use of soil slurry reactors. Conversely, many different bioreactor designs exist for the treatment of water contaminated with PAHs. As reviewed by Grady (1989) and Grady Lim (1980), these include fixed film reactors, plug flow reactors, and a variety of gas-phase systems, to name a few. Given the depth and magnitude of such a topic, for the purposes of this review discussions will be limited to a generic overview of reactor applications for PAH bioremediation. 

In the third section an extensive writing on two types of slurry catalytic reactors is proposed Bubble Slurry Column Reactors (BSCR) and Mechanically Stirred Slurry Reactors (MSSR). All the variables relevant in the design and for the scale-up and the scale-down of slurry catalytic reactors are discussed particularly from the point of view of hydrodynamics and mass transfer. Two examples of application are included at the end of the section. 

We will now consider the design of an agitated tank slurry reactor which might be used industrially for this reaction. We will choose a particle size of 100 fim rather than the very small size particles used in the laboratory experiments, the reason being that industrially we should want to be able easily to separate the catalyst particles from the liquid products of the reaction. If we use spherical particles (radius ro, diameter dp), the Thiele modulus (see Chapter 3) is given by ... 

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