Packed tubular reactors

In a substantial majority of the cases where packed tubular reactors are employed the flow conditions can be regarded as those of plug flow. However, dispersion (already discussed in Chapter 2 in relation to homogeneous reactors) may result in lower conversions than those obtained under truly plug flow conditions. 

In the first instance, the effects of dispersion will be disregarded. Then the effects of dispersion in the axial (longitudinal) direction only will be taken into account and this discussion will then be followed by considerations of the combined contributions of axial and radial (transverse) dispersion. 

Suppose that a mass of catalyst, whose bulk density is pb, is contained within an elementary length Sz of a reactor of uniform cross-section Ac. The mass of catalyst 

If axial dispersion were an important effect, the reactor performance would tend to fall below that of a plug flow reactor. In this event an extra term must be added to equation 3.87 to account for the net dispersion occurring within the element of bed. This subject is considered later. 

Carbon disulphide is produced in an isothermally operated packed tubular reactor at a pressure of 1 bar by the catalytic reaction between methane and sulphur. 

---

Quite new ideas for the reactor design of aqueous multiphase fluid/fluid reactions have been reported by researchers from Oxeno. In packed tubular reactors and under unconventional reaction conditions they observed very high space-time yields which increased the rate compared with conventional operation by a factor of 10 due to a combination of mass transfer area and kinetics [29]. Thus the old question of aqueous-biphase hydroformylation "Where does the reaction takes place " - i.e., at the interphase or the bulk of the liquid phase [23,56h] - is again questionable, at least under the conditions (packed tubular reactors, other hydrodynamic conditions, in mini plants, and in the unusual,and costly presence of ethylene glycol) and not in harsh industrial operation. The considerable reduction of the laminar boundary layer in highly loaded packed tubular reactors increases the mass transfer coefficients, thus Oxeno claim the successful hydroformylation of 1-octene [25a,26,29c,49a,49e,58d,58f], The search for a new reactor design may also include operation in microreactors [59]. 

PACKED TUBULAR REACTOR MODELING AND CATALYST DESIGN USING COMPUTATIONAL FLUID DYNAMICS... 

An approximate design procedure for packed tubular reactors entails the assumption of plug flow conditions through the reactor. Discuss critically those effects which would ... 

A packed tubular reactor is used to produce a substance D at a total pressure of 100 kN/m2 (1 bar) utilising the exothermic equilibrium reaction ... 

P8.01.04. PACKED TUBULAR REACTOR HEAT AND MATERIAL BALANCES... 

For a process in a packed tubular reactor like that of P8.01.02, the steady material balance is derived there as... 

Optimization of a distributed parameter system can be posed in various ways. An example is a packed, tubular reactor with radial diffusion. Assume a single reversible reaction takes place. To set up the problem as a nonlinear programming problem, write the appropriate balances (constraints) including initial and boundary conditions using the following notation ... 

SJi. The initial startup of an adiabatic, gas-phase packed tubular reactor makes a good example of how a distributed system can be lumped into a series of CSTRs in order to study the dynamic response. The reactor is a cylindrical vessel (3 feet ID by 20 feet long) packed with a metal packing. The packing occupies 5 percent of the total volume, provides 50 ft of area per of total volume, weighs 400 ib yft and has a heat capacity of 0.1 Btu/lb °F. The heat transfer coefficient between the packing and the gas is 10 Btu/h It "F. 

Different approaches to overcome the discussed limitations have been published [152,153,177]. Wiese et al. reported that space-time yields increased by a factor of ten when using a packed tubular reactor and altered operating conditions compared to those in a conventional stirred tank reactor [ 176]. 

---