Batch reactors evaluation

With regard to mistakes, two separate mechanisms operate. In the rule-based mode, an error of intention can arise if an incorrect diagnostic rule is used. For example, a worker who has considerable experience in operating a batch reactor may have learned diagnostic rules that are inappropriate for continuous process operations. If he or she attempts to apply these rules to evaluate the cause of a continuous process disturbance, a misdiagnosis could result, which could then lead to an inappropriate action. In other situations, there is a tendency to overuse diagnostic rules that have been successful in the past. 

All the results obtained for isothermal, constant-density batch reactors apply to isothermal, constant-density (and constant cross-section) piston flow reactors. Just replace t with z/u, and evaluate the outlet concentration at z = L. Equivalently, leave the result in the time domain and evaluate the outlet composition t = L/u. For example, the solution for component B in the competitive reaction sequence of... 

In this work, the waste brewery yeast and Aspergillus niger were used for the adsorption of lead, copper and cadmium, and their cyanide complexes. Biosorption equilibrium was studied in a batch reactor with respect to pH, initial concentration of heavy metal and metal-cyanide complex. Biosorption equilibrium over the temperature range of 288K - 308K was investigated and the biosorption heat was evaluated. 

This work was initiated for the purpose of evaluating the feasibility of synthesizing hexyl acetate (ROAc) fi-om n-hexyl bromide (RBr) and sodium acetate (NaOAc) by a novel PTC technique. In this new technique, the solid-liquid reaction was catalyzed by a catalyst-rich liquid phase in a batch reactor. Because there a solid phase and two liquid phases coexist, it is called as a SLL-PTC system [3]. Actually, this liquid phase is the third liquid phase in the tri-liquid PTC system. It might be formed when the phase-transfer catalyst is insoluble or slightly soluble in both aqueous and organic phases. Both aqueous and organic reactants can easily transfer to this phase where the intrinsic reaction occurs [4, 5]. 

Modelling can at least facilitate the determination of the most effective scale-up program. Information from three fields is needed for modelling (1) chemical kinetics, (2) mass transfer, and (3) heat transfer. The importance of information for different processes has been qualitatively evaluated (see Table 5.3-5). Obviously, sufficiently accurate information on heat transfer is needed for batch reactors, which are of great interest for fine chemicals manufacture. Kinetic studies and modelling requires much time and effort. Therefore, the kinetics often is not known. Presently, this approach is winning in the scale-up of processes for bulk chemicals. The tools developed for scale-up of processes for bulk chemicals have been proven to be very useful. Therefore, the basics of this approach will be discussed in more detail in subsequent sections. 

As an example for precise parameter estimation of dynamic systems we consider the simple consecutive chemical reactions in a batch reactor used by Hosten and Emig (1975) and Kalogerakis and Luus (1984) for the evaluation of sequential experimental design procedures of dynamic systems. The reactions are... 

We evaluated a number of potential catalysts and conditions using xylitol as a model compound in a batch reactor. A catalyst was selected from this initial screening and examined in a continuous trickle-bed reactor to develop operating conditions. Finally, as resources allowed, the catalyst was evaluated in a trickle bed reactor to gain a concept of potential catalyst lifetime. 

The initial screening of the resin catalysts was done in a batch reactor at supercritical for butene-1 conditions of temperature 155 °C, pressure of 1000 psig and at molar ratio of 1-butene water of 5.5. The reaction was stopped after predetermined period of time and the products analyzed. It was found that under the standard reaction conditions, for all of the catalysts studied, a constant concentration in the sec-butanol concentration was achieved within a 1-2 hour reaction time. Using only the linear section of the concentration-time plot, the one hour result was used to evaluate the catalyst activity, which was normalized as mmol of SBA/ per proton/ per hour (a), as mmol of product/ per gram of dry catalyst/ per hour (b) and mmol of product/ per ml of wet catalyst/ per hour (c). 

Hence the area under the curve of y versus CA multiplied by the ratio of stoichiometric coefficients represents the overall change in valuable product concentration between the inlet and outlet streams in a plug flow reactor or in a batch reactor. For the case of a CSTR the instantaneous yield is evaluated at the effluent composition, and the corresponding equation is... 

Recent reports on other forms of reactors are also available. Immobilized cell bioreactors, upflow sludge blanket reactors, draft-tube airlift reactor and other have been suggested. Each of these reactors has its own pros and cons and the advantages need to be evaluated with the whole process in mind. Further work is necessary in this area. Several process schemes have been considered and evaluated with the batch reactor design as the core BDS reactor ... 

Figure 29.3 Evaluation of the constants of the Monod equation from batch reactor data, method (b). ...

Soil slurry-sequencing batch reactor (SS-SBR) is a technology for the biological treatment of organic contaminants in soil. The technology has been evaluated in full-scale field tests but is not commercially available. The SS-SBR system consists of a set of tanks operated on a fill-and-draw basis. Each tank is filled during a discrete period of time and operated as a batch reactor. According to the vendor, reaction times are on the order of days. 

The batch reactor, above described, permits both to operate at quasi-zero conversion per pass and to evaluate the cat ytic activity at finite values of the reagents conversion. A typical test performed on Si02 catalyst at 600°C is presented in Figure 1. It is remarkable how in our approach the product selectivity is unaffected by the methane conversion. A special care was taken to avoid oxygen-limiting conditions and, hence, methane conversion data obtained for oxygen conversions below 20% only have been used for the calculation of reaction rates. 

In conclusion, the maximum adsorption capacity should be measured in fixed-bed experiments under dynamic conditions, and if models are applicable, diffusion coefficients should be also determined in fixed-bed apparatus. Due to the fact that the equilibrium isotherms require extended data series and thus are time-consuming experiments, the latter are quite difficult to be conducted in fixed-bed reactors and from this point of view, it is more practical to evaluated equilibrium isotherms in batch reactor systems. Then, it is known that when applying fixed-bed models using an equilibrium isotherm obtained in batch-type experiments, the equilibrium discrepancy (if it exists) can be compensated by a different estimate for the solid diffusion coefficient (Inglezakis and Grigoropoulu, 2003 Weber and Wang, 1987). 

Applications of kinetic principles to industrial reactions are often useful. Initial kinetic studies of the esterification reaction are usually conducted on a small scale in a well stirred batch reactor. In many cases, results front batch studies can be used in the evaluation of the esterification reaction in a continuous operating configuration. 

A limitation of the methods described so far is that they have assumed a constant overall yield coefficient and do not allow the endogenous respiration coefficient kd (or alternatively the maintenance coefficient, m) to be evaluated. Equation 5.54 shows that the overall yield, as measured when monitoring a batch reactor, is affected by the growth rate and has the greatest impact when the growth rate is low. Consequently, it is desirable to be able to estimate the values of kd or m, so that the yield coefficient reflects the true growth yield. An equivalent method would be one where the specific rates of formation of biomass and consumption of substrate were determined independently, again without the assumption of a constant overall yield-coefficient. 

Utilizing a commercially available microreactor, fabricated from FOR-TURAN glass, Fukuyama et al. (2004) evaluated a series of [2 + 2] cycloadditions as a means of reducing the reaction times conventionally associated with the synthetic transformation (Table 27). Using a high-pressure mercury lamp (300 W), the reaction of cyclohex-2-eneone 179 with vinyl acetate 168 (Scheme 51), to afford the cycloadduct 180, was used to compare photochemical efficiency within the microreactor [1,000 pm (wide) x 500 pm (deep)] and a conventional batch reactor (10 ml). 

In small industrial pilot plants, a batch system may be employed for preliminary information. Also, batch reactors can be used in these plants to obtain small quantities of the new product for further evaluations such as purity, yield, and sales. At the industrial level, batch... 

Using Equation 11-26 for the batch reactor, the dependent variable 1/t ln(Cso/Cs) is plotted as a function of the independent variable (Cso - Cs)/t. A linear plot gives a slope = -1/Km and an intercept = Vmax/ Km. The values of Km and Vmax are determined from the slope and the intercept. k3 is evaluated from Vmax = k3CET, or... 

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