Reactor length

Duarte and colleagues used a factorial design to optimize a flow injection analysis method for determining penicillin potentiometricallyd Three factors were studied—reactor length, carrier flow rate, and sample volume, with the high and low values summarized in the following table. 

Although it appears that methyl ethyl ketone [78-93-3] caimot be the principal product in butane LPO, it has been reported that the ratio of methyl ethyl ketone to acetic acid [64-19-7] can be as high as 3 1 in a plug-flow-type reactor (214). However, this requires a very unusual reactor (length dia = 16, 640 1). The reaction is very unstable and wall reactions may influence mechanisms. 

Fig. 2. Profiles of conversion, A, having pressure P and gas temperature T along the reactor length. Residence time, B, where W = maximum wall temperature. To convert kPa to bar, divide by 100.

This result means that the reactor is insensitive if the temperature profile is concave toward the reactor length axis, and the inflection point is avoided. If the AT exceeds that permitted by the previous criterion—the limit set by RT /E— an inflection of the temperature vs., tube length will occur and thermal runaway will set in. Just before runway sets in the temperature at the hot spot can be 1.4 times higher than RT /E. 

Calculate the reactor temperature and conversion as a function of reactor length and comment on the results. 

In a tubular reactor system, the temperature rises along the reactor length for an exothermic reaction unless effective cooling is maintained. For multiple steady states to appear, it is necessary that a... 

A feed concentration of 15 g glucose and 15 g xylose per litre was used over a feed rate of 20-200 ml/hr. Samples were taken at successive points along the reactor length, and the usual analysis for glucose and xylose consumption, organic acid production and cell density were done. A kinetic model for the growth and fermentation of P. acidipropionici was obtained from these data. 

Equation (8.4.3) is a linear first-order differential equation of concentration and reactor length. Using the separation of variables technique to integrate (8.4.3) yields... 

Thus a lineal- relation between In (CA/CA0) and the reactor length should exist if the model accurately describes the immobilised cell reactor. The experimental data fitting the model was discussed earlier. 

The integration of equations (A-ll) to (A-13) and (A-15) and (A-16) along the reactor length in combination with equation (A-1) and (A-2) will give the molecular weight. 

Determine the reactor length, diameter, Reynolds number, and scaling factor for pressure drop for the scaleup with constant heat transfer in Example 5.12. 

An example of integrated heat-transfer modehng and reactor design is shown in Figure 11.6. A predicted thermal profile for the reactor section of a combined reactor-heat exchanger is the solid line, while the discrete points are experimentally measured temperatures along the reactor length. The thermal profile is controlled... 

In the model equations, A represents the cross sectional area of reactor, a is the mole fraction of combustor fuel gas, C is the molar concentration of component gas, Cp the heat capacity of insulation and F is the molar flow rate of feed. The AH denotes the heat of reaction, L is the reactor length, P is the reactor pressure, R is the gas constant, T represents the temperature of gas, U is the overall heat transfer coefficient, v represents velocity of gas, W is the reactor width, and z denotes the reactor distance from the inlet. The Greek letters, e is the void fraction of catalyst bed, p the molar density of gas, and rj is the stoichiometric coefficient of reaction. The subscript, c, cat, r, b and a represent the combustor, catalyst, reformer, the insulation, and ambient, respectively. The obtained PDE model is solved using Finite Difference Method (FDM). 

Figure 7.21. Fraction of unoccupied sites, and of sites occupied by atomic nitrogen and NH, as a function of reactor length on a potassium-promoted iron ammonia catalyst at 673 K,...

Figure 7.22. NH3 concentration as a function of reactor length in the synthesis of ammonia with a potassium-promoted iron catalyst. The exit concentration is 19 % and corresponds to...

The simultaneous integration of the two continuity equations, combined with the chemical kinetic relationships, thus gives the steady-state values of both, Ca and T, as functions of reactor length. The simulation examples BENZHYD, ANHYD and NITRO illustrate the above method of solution. 

The results of the calculation are thus the mole fraction compositions, yA and yB, together with the total volumetric flow rate G, as steady-state functions of reactor length. 

The coupling of the component and energy balance equations in the modelling of non-isothermal tubular reactors can often lead to numerical difficulties, especially in solutions of steady-state behaviour. In these cases, a dynamic digital simulation approach can often be advantageous as a method of determining the steady-state variations in concentration and temperature, with respect to reactor length. The full form of the dynamic model equations are used in this approach, and these are solved up to the final steady-state condition, at which condition... 

In the above case, D is an eddy dispersion coefficient and Z is the axial distance along the reactor length. When combined with an axial convective flow contribution, and considering D as constant, the equation takes the form... 

Thus the problem involves the two independent variables, time t and length Z. The distance variable can be eliminated by finite-differencing the reactor length into N equal-sized segments of length AZ such that N AZ equals L, where L is the total reactor length. 

UNSTEADY-STATE FINITE DIFFERENCED MODEL REACTOR LENGTH DIVIDED INTO 8 EQUAL ELEMENTS... 

The RTD quantifies the number of fluid particles which spend different durations in a reactor and is dependent upon the distribution of axial velocities and the reactor length [3]. The impact of advection field structures such as vortices on the molecular transit time in a reactor are manifest in the RTD [6, 33], MRM measurement of the propagator of the motion provides the velocity probability distribution over the experimental observation time A. The residence time is a primary means of characterizing the mixing in reactor flow systems and is provided directly by the propagator if the velocity distribution is invariant with respect to the observation time. In this case an exact relationship between the propagator and the RTD, N(t), exists... 

---