Tubular reactor design

Fig. 4. Continuous tubular reactor design. Courtesy of BatteUe.

Equating the time of passage through the tubular reactor to that of the time required for the batch reaction, gives the equivalent ideal-flow tubular reactor design equation as... 

Packed-bed reactors, 21 333, 352, 354 Packed beds, 25 718 Packed catalytic tubular reactor design with external mass transfer resistance, 25 293-298 nonideal, 25 295... 

Many tubular reactor designs depend on high velocities to avoid deposition of particles in the reactor [112,117,118], However, when the high velocities are applied by use of a small diameter, a reactor length of hundreds of feet is required to achieve the required residence time. Therefore, the principles of keeping solids from depositing by high velocities have not been demonstrated at any acceptable scale. 

Barnes CM. Evaluation of tubular reactor designs for supercritical water oxidation of U.S. Department of Energy mixed waste. INEL-94/0223, Lockheed Idaho Technologies Co., Idaho Falls, ID, 1994. 

There is no limit to the number of reactor grades that can be produced. The product mix can be adjusted to match market demand and economical product ranges. Advantages for the tubular reactor design with low residence time are easy and quick transitions, startup and shutdown. 

However, each set of factors entering in to the rate expression is also a potential source of scaleup error. For this, and other reasons, a fundamental requirement when scaling a process is that the model and prototype be similar to each other with respect to reactor type and design. For example, a cleaning process model of a continuous-stirred tank reactor (CSTR) cannot be scaled to a prototype with a tubular reactor design. Process conditions such as fluid flow and heat and mass transfer are totally different for the two types of reactors. However, results from rate-of-reaction experiments using a batch reactor can be used to design either a CSTR or a tubular reactor based solely on a function of conversion, -r ... 

To obtain some insight into things to come, consider the following example of how one can use the tubular reactor design equation (1-10). 

The objective of this section is to provide a brief overview of selected chemistries and processes that are based upon various tubular reactor designs to illustrate more practical aspects. As the partial oxidation process is a key manufacturing technology that utilizes various tubular reactor designs, most of the emphasis will be placed here. The extension of the same concepts to other chemistries, such as hydrogenation reactions, is based upon similar principles. 

C. M. Barnes, Evaluation of Tubular Reactor Designs for Supercritical Water Oxidation of U.S. Department of Energy Mixed Waste, Idaho National Engineering Laboratory Report INEL-94/0223, December, 1994. 

Consider a feedstock consisting of 75.0% v/v acetaldehyde, 5.0% oxygen, and 20.0% nitrogen. For a tubular reactor designed for isothermal operation at 200°C and 1.5 atm, determine the space time necessary to achieve 99% conversion of the limiting reagent. Ideal gas behavior may be assumed. 

At the present state these correlations together with Eq. 23 for the prediction of the apparent heat conductivity amd Eq. 6, 7 for the particle-to-fluid heat transfer may be recommended for application in tubular reactor design. These correlations give fairly reliable parameters for either homogeneous or heterogeneous one or two dimensional models for the mathematical simulation of packed bed reactors. 

Fig. 6.19 Tubular reactor design where the tube is made of a CEM and contains conductive graphite granules packed into the center of the tube, with the ferricyanide cathoiyte fluid overflowing the outside of the column which is covered with a thick woven graphite mat. (A) Schematic. [Reprinted from Rabaey et al. (2005b), with permission of the American Chemicai Society.] (B) Photograph of the reactor. (Provided by K. Rabaey, Ghent University.)...

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