Types of Industrial Reactors

Technical Realization of the Fischer-Tropsch Syntheas 3.1. TYPES OF INDUSTRIAL REACTORS 

The revolutionary work of Fischer and Tropsch had been carried out in a fixed-bed reactor consisting of a simple 5 mm ID glass tube. With larger reactors however, the effective removal of heat produced by the exothermic reaction becomes the main problem. Three types of reactors have been developed for the technical realization of the process [3, 15] Fixed-bed fluidized-bed or entrained tluidized-bed and slurry-bed. 

Fixed-bed reactors arc suitable for lower temperature ranges, but because of slow heat transfer, their temperature control problem can only partly be overcome by high gas recycling. For catalyst regeneration the process must be interrupted. 

Product dhtributiuns ubtalned by commercial processes over I e catalysts at Sasol 4  

Recent investigations have shown that increasing the diameter of a fixed bed reactor accelerates plugging by carbonaceous or waxy deposits. Plugging is also found at higlt temperature or low Hj/CO operation and is related with local nonuniformity in the catalyst temperatures [22. Kinetic measurements on laboratory-scale recycle reactors have been used to predict product distributions for pilot plant reactors and were in good agreement with experimental results 1231. 

The polymerization of olefins with coordination catalysts is performed in a large variety of polymerization processes and reactor configurations that can be classified broadly into solution, gas-phase, or slurry processes. In solution processes, both the catalyst and the polymer are soluble in the reaction medium. These processes are used to produce most of the commercial EPDM rubbers and some polyethylene resins. Solution processes are performed in autoclave, tubular, and loop reactors. In slurry and gas-phase processes, the polymer is formed around heterogeneous catalyst particles in the way described by the multigrain model. Slurry processes can be subdivided into slurry-diluent and slurry-bulk. In slurry-diluent processes, an inert diluent is used to suspend the polymer particles while gaseous (ethylene and propylene) and liquid (higher a-olefins) monomers are fed into the reactor. On the other hand, only liquid monomer is used in the slurry-bulk pro- 

Several polymerization processes use only one reactor, but two or more reactors can also be operated in series (tandem reactor technology) to produce polyolefins with more complex microstructures [5]. Each reactor in the series is maintained under different operating conditions to produce products that are sometimes called reactor blends . Although, in principle, the post-reactor blending of different resins could lead to the same product, in reactor blends the chains are mixed on the molecular scale, permitting better contact between the polymer chains made in different reactors at a lower energy cost. 

Consider first the case of two tubular reactors in series, making high-impact polypropylene. Reactor 1 produces isotactic polypropylene, while random ethylene-propylene copolymer is made in Reactor 2. Assuming that both reactors are ideal plug-flow reactors, the residence time of all the polymer particles in each reactor is exactly the same. Consequently, if the distribution of active sites in the 

A very different picture emerges when using two CSTRs in series. Because the residence time distribution of an ideal CSTR, E(t), with average residence time is given by the usual exponential decay equation [Eq. (110)], then some particles will leave Reactor 1 after a short time while others will only leave after spending a considerably longer time in the reactor. 

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From this general mole balance equation we can develop the design equations for the various types of industrial reactors batch, semibatch, and continuous-flow. Upon, evaluation of these equations we cau determine the time (batch) or reactor volume (continuous-flow) necessary to convert a specified amount of the reactants to products. 

The aim of the preceding discussion on commercial reactors is to give a more detailed picture of each of the major types of industrial reactors batch, semibatch, CSTR, tubular, fixed-bed (packed-bed), and iiuidized-bed. Many variations aird modifications of these commercial reactors are in current use for further elaboration, refer to the detailed discussion of industrial reactors given by Walas. ... 

The first chapter focused on the general mole balance equation die balance was applied to the four most common types of industrial reactors, and a design equation was developed for each reactor type. In Chapter 2 we first define con-version and then rewrite the design equations in terms of conversion. After car rying out this operation, we show how one may size a reactor i.e., determine the reactor volume necessary to achieve a specified conversion) once the relationship between reaction rate, r, and conversion is known. 

The conventional MTBE synthesis consists of a reaction of isobutene and methanol over an acidic sulfonated cation-exchange catalyst. This reaction is highly selective, equilibrium-limited, and exothermic in nature. Several types of industrial reactors such as tubular reactors, adiabatic reactors with recycle, and catalytic distillation configurations have been utilized to cany out the MTBE synthesis reaction. The factors considered in the optimal design of a MTBE unit include the following items [52]. 

Overview—Chapter 1, This chapter develops the first building block of chemical reaction engineering, mole balances, that will be used continually throughout the text. After completing this chapter the reader will be able to describe and define the rate of reaction, derive the general mole balance equation, and apply the genera mole balance equation to the four most common types of industrial reactors. 

Various types of industrial reactors may occur in different phases as applications and desired properties of the final product, for example, the fixed bed, fluidized bed, slurry bed, and bed phase reactors. In fluidized bed reactors as in slurry bed, the solid (catalyst) is composed of very small particles and moving along the reactor. The fluid flow over these reactors is complex. In these systems, the flow of the fluid phase is not homogeneous and there are large deviations from the ideal behavior of a CSTR or plug flow reactor (PFR), characterizing them in nonideal reactors. 

Apply the general mole balance equation to the four most common types of industrial reactors... 

Overview. In the hrst chapter, the general mole balance equation was derived and then applied to the four most commcm types of industrial reactors. A balance equation was deveicqred fcM each reactor type and these equations are summarized in Table 1 in Chapter L In Chapter 2, we will show how to size and arrange these reactors conceptually, so that the reader may see the structure of CRE design and will not get lost in the mathematical details. 

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