Summary of Reactor Ratings

Reactor Type Sampling and Analysij Isoihermaliiy Flmd SoliJ Contact Catatysi Ease / Construction 

Plot ln —(/C /c/() versus InC. The slope will be the reaction order a, could use tinite-ditTerence formulas or software packages to evali (—as a function of time and concentration. 

In this method of analysis of rate data, the slope of a plot of ln(—r nQ) vei In C o will be the reaction order. 

---

Summary of reactor ratings, gas-liquid, powdered catalyst, decaying catalyst system... 

Table 5-4. Summary of Reactor Ratings Gas-Liquid, Powdered Catalyst, Decaying Catalyst SYsraa ...

Table 5-4. summary of reactor Ratings GAS-LiQuro,lTMTE[M)CATAL)Sr, Decaying Catalyst System ... 

A summary of reactor models used by various authors to interpret trickle-bed reactor data mainly from liquid-limiting petroleum hydrodesulfurization reactions (19-21) is given in Table I of reference (37). These models are based upon i) plug-flow of the liquid-phase, ii) the apparent rate of reaction is controlled by either internal diffusion or intrinsic kinetics, iii) the reactor operates isothermally, and iv) the intrinsic reaction rate is first-order with respect to the nonvolatile liquid-limiting reactant. Model 4 in this table accounts for both incomplete external and internal catalyst wetting by introduction of the effectiveness factor r)Tg developed especially for this situation (37 ). 

It covers briefly the theory of interacting chemical rate processes with physical ones and the possible influence of mixing on reaction yields. Some suggestions are given on experimentation to elucidate the relative importance of the two rate processes and finally a summary of reactor modelling techniques suitable for gas-liquid systems. 

Continuous Polymerizations As previously mentioned, fifteen continuous polymerizations in the tubular reactor were performed at different flow rates (i.e. (Nj g) ) with twelve runs using identical formulations and three runs having different emulsifier and initiator concentrations. A summary of the experimental runs is presented in Table IV and the styrene conversion vs reaction time data are presented graphically in Figures 7 to 9. It is important to note that the measurements of pressure and temperature profiles, flow rate and the latex properties indicated that steady state operation was reached after a period corresponding to twice the residence time in the tubular reactor. This agrees with Ghosh s results ). 

Table 10.4-1. Summary of trends in the deposition rate and non-uniformity responses to increases in each of the geometric parameters in the reactor.

Reductive Carbonylation of Methanol. The reductive carbonylation of methanol (solvent free) was studied at variable I/Co, PPh,/I, temperature, pressure, synthesis gas ratio and methanol conversion (gas uptake) in the batch reactor, A summary of the results is given in Table I. In general, the acetaldehyde rate and selectivity increase with increasing I/Co. The PPh /I ratio has little effect except in run //7 where the rate is drastically reduced at I/Co =3.5 and PPh /I r 2. A good set of conditions is I/Co =3 5 and PPh /I = 1,T where the acetaldehyde rate and selectivity is 7.6 M/nr and 765 at 170 °C and 5000 psig. The effect of methanol conversion at these conditions is obtained by compearing runs 13, 1, 14, and 15. The gas uptake was varied from 14000 to 4000 psi, which corresponds to observed methanol conversions of 68% to 38 te. 

TABLE 1 Summary of Estimated Costs in Dollars/Ton (0.90718 metric ton) for Various Feed Rates and Influent Concentrations for Gas-Phase Corona Reactor Treatment of Volatile Organic Compounds... 

Table 1. Summary of relative reactor ratings (L = low, M = medium, H = high).

Al-Saleh et al. [Chem. Eng. J., 37 (1988) 35] performed a kinetic study of ethylene oxidation over a silver supported on alumina catalyst in a Betty reactor. At temperatures between 513-553 K and a pressure of 21.5 atm, the observed reaction rates (calculated using the CSTR material balance) were independent of the impeller rotation speed in the range 350-1000 rpm (revolutions per minute). A summary of the data is ... 

In summary, for many reactions involving multiple steps and pathways, the powers in the rate laws surprisingly agree with the stoichiometric coefficients. Consequently, to facilitate describing this class of reactions, we say a reaction/o//o>v.t an elementary rate law when the reaction orders are identical with the stoichiometric coefficients of the reacting species for the reaction as written. It is important to remember that the rate laws are determined by experimental observation They are a function of the reaction chemistry and not the type of reactor in which the reactions occur. Table 3-1 gives examples of rate laws for a number of reactions. 

A summary of the merits of the various reactor types begins by first noting that the BR has little merit as a device for rate measurements. Its hoped-for simplicity is often not possible to implement in practice and the limitations of data acquisition are serious. The flow reactors are clearly to be preferred and allow us to measure conversion at a greater number of reaction times and conversions. They also allow duplicate measurements to be made at any point. Unfortunately, the need for steady state to be established makes the acquisition of data in flow reactors tedious and time consuming. Moreover, the collected data consists of independent measurements each with its own error, often collected days apart. This procedure will tend to increase the magnitude of the error and to complicate subsequent efforts directed at its removal from the raw data. 

Table 8.1 contains a summary of the fundamental design relations for the various types of ideal reactors in terms of equations for reactor space times and mean residence times. The equations are given in terms of both the general rate expression and nth-order kinetics. 

In summary, the sizing of the reactors should be based on the rate of polymerization data from pilot-scale investigations or (preferably) previous plant experience, while the choice of reactor type should be made based on kinetic as well as economic considerations. The effect of the CSTR residence time distribution on each of the three common types of polymerization kinetics will now be discussed. 

---