Fluidized bed reactor design

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. 

In spite of the drawbacks enumerated above, fluidized bed reactors have a number of compelling advantages, as we have noted previously. By proper design it is possible to overcome their deficiencies so that their advantages predominate. This book does not discuss in detail the manner in which this problem can be solved, although the design considerations outlined in subsequent sections of this chapter are quite pertinent. For detailed treatments of fluidized bed reactor design, consult the excellent reference works by Kunii and Levenspiel (3) and by Davidson and Harrison (4). 

This paper uses pyrolysis products from an air-blown, fluidized-bed reactor designed to produce liquids for use in adhesives as an illustration of what might be produced, separated and sold commercially for higher value. Guidelines for chemicals production and product recovery are suggested for pyrolysis processes in general. Recommended research and development topics to aid commercialization and increase chemical product recovery and project cash flow are presented. 

Numerous types of fluidized bed reactor designs exist within each of the two categories mentioned in the previous subsection, some of them are illustrated in Fig 10.7. The key issues leading to re-design of the primary bubbling bed are also indicated. 

Chapter 10 contains a literature survey of the basic fluidized bed reactor designs, principles of operation and modeling. The classical two- and three phase fluidized bed models for bubbling beds are defined based on heat and species mass balances. The fluid dynamic models are based on kinetic theory of granular flow. A reactive flow simulation of a particular sorption enhanced steam reforming process is assessed. 

The application of the two-phase theory to fluidized-bed reactor design is illustrated in Case Study 11.5. 

Coke Control at Macroscale Optimize the DMTO Fluidized Bed Reactor Design and Operation... 

As a typical multiphase and multiscale process, the research of MTO process spanning molecules, zeohtes, catalyst particles, microscale reactors, and pilot-scale reacton to industrial equipments, cross a wide time and length scales. The development of efficient mesoscale methods are expected for further optimizing the DMTO process and improving fluidized bed reactor design and operation. 

Fluidized-bed reactor design for solid catalyzed fluid-phase reactions... 

Outline a methodology for the selection of the most plausible model for the solid catalyzed fluidized-bed reactor design. 

How much did computational fluid dynamics (CFD) enter into the actual design of the fluidized-bed reactors Perform a thorough literature survey and find a solid evidence of the use of CFD tools in fluidized-bed reactor design. 

The fluidized bed reactor design requires understanding the reaction chemistry. The essential knowledge for a design engineer may include the reaction kinetics, conversion or yield, and selectivity, thermodynamics, and process parameters (e.g., operating temperature and pressure as well as heat of reaction) affecting the reaction. 

Fixed Bed Nuclear Reactor (FBNR) [1,2] is a simplified version of the fluidized bed nuclear reactor [3-14]. In FBNR spherical fuel elements are at a fixed position within the core, therefore there is no concern about the consequences of friction between them, as often raised in relation to fluidized bed concept. In the latter case there is a need to study the degree of erosion in order to determine the required clad thickness. There is little work done on the fixed bed nuclear reactor concept so far, but the experience gained from the fluidized bed reactor design could essentially facilitate the development of FBNR. 

Figure 5.17 Early gas-phase fluidized-bed reactor design from Phillips Petroleum Co. [32].

Because of the particular complexities presented by a new process, industrial fluidized bed reactor design is almost always done as a custom job. A handbook approach is just not possible. If the company does not have extensive experience in the fluidization field (or even if it has), consultants with years of practical design and development experience should be consulted. Management would be foolish, indeed, to embark on a venture which is going to cost possibly hundreds of millions of dollars and require several years of effort without getting its hands on the best information, experience and judgement available. 

Lindborg H, Jakobsen HA (2009) Sorption enhanced steam methane reforming process performance and bubbling fluidized bed reactor design analysis by use of a two-fluid model. Ind Eng Chem Res 48 1332-1342... 

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