Batch reactor monitoring

The decomposition of nitrous oxide (NjO) to nitrogen and oxygen is preformed in a 5.0 1 batch reactor at a constant temperature of 1,015 K, beginning with pure NjO at several initial pressures. The reactor pressure P(t) is monitored, and the times (tj/2) required to achieve 50% conversion of N2O are noted in Table 3-19. Use these results to verify that the N2O decomposition reaction is second order and determine the value of k at T = 1,015 K. 

The experimental method used for this kinetie study is reaetion ealorimetry. In the ealorimeter, the energy enthalpy balance is continuously monitored the heat signal can then be easily converted in the reaction rate (in the case of an isothermal batch reactor, the rate is proportional to the heat generated or consnmed by the reaction). The reaction orders and catalyst stabihty were determined with the methodology of reaction progress kinetic analysis (see refs. (8,9) for reviews). 

Dabert P, Fleurat-Lessard A, Mounier E et al (2001) Monitoring of the microbial community of a sequencing batch reactor bioaugmented to improve its phosphorus removal capabilities. Wat Sci Technol 43 1-3... 

A common laboratory device is a batch reactor, a nonflow type of reactor. As such, it is a closed vessel, and may be rigid (i.e., of constant volume) as well. Sample-taking or continuous monitoring may be used an alternative to the former is to divide the reacting system into several portions (aliquots), and then to analyze the aliquots at different times. Regardless of which of these sampling methods is used, the rate is determined indirectly from the property measured as a function of time. In Chapter 3, various ways of converting these direct measurements of a property into measures of rate are discussed in connection with the development of the rate law. 

In terms of cost and versatility the batch reactor is the unit of choice. One disadvantage is the need for frequent sampling or monitoring of the performance, although instrumentation can be provided at moderate cost nowadays. The residence time can be varied over a wide range and many different reactions can be handled at different times. The quality of mixing and heat transfer may not be easy to relate to those in an eventual commercial unit. 

Wang et al. [42,67,68] have developed innovative biological process and sequencing batch reactors (SBR) specifically for removal of volatile organic compounds (VOCs) and surfactants. Related analytical procedures [57-64,71-91] available for process monitoring and control are available in the literature. 

Aqueous A at a concentration C o = 1 mol/liter is introduced into a batch reactor where it reacts away to form product R according to stoichiometry A R. The concentration of A in the reactor is monitored at various times, as shown below ... 

Metathesis activity. A quantitative comparison of metathesis activities was made in the gas phase homometathesis of propylene. The reaction kinetics are readily monitored since all olefins (propylene, ethylene, cis- and fra/3s-2-butylenes) are present in a single phase. Metathesis of 30 Torr propylene was monitored in a batch reactor thermostatted at 0 °C, in the presence of 10 mg catalyst. The disappearance of propylene over perrhenate/silica-alumina (0.83 wt% Re) activated with SnMe4 is shown in Figure 2a. The propylene-time profile is pseudo-first-order, with kob (1.11 + 0.04) X 10" slightly lower rate constant, (0.67 constants are linearly dependent on Re loading. Figure 3. The slope yields the second-order rate constant k = (13.2 + 0.2) s (g Re) at 0°C. 

The real-time monitoring of dissolved molecules has already been demonstrated above for a batch reactor (Fig. 10). Figure 19 gives an example of data obtained with a continuous reactor of the type shown in Fig. 12. The example was chosen to illustrate the excellent time resolution of the method, which is limited by mass... 

ATR-IR spectroscopy can be used as a spy inside a reactor for on-line monitoring and control of a reaction. The emphasis in this kind of application of ATR spectroscopy is on the detection of reactants and products in the bulk fluid phase. Such applications benefit from the excellent time resolution of FTIR instruments compared to other analytical tools, such as chromatographs. The method can be used in investigations of kinetics of reactions in batch reactors instrumentation has been developed and even commercialized that allows measurements at elevated temperatures and pressures. 

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. 

An important parameter in a number of fields is the study of inorganic phosphate. Recently, Kwan et al. [206,207] have reported on a screen-printed phosphate biosensor based on immobilised pyruvate oxidase (PyOD) for monitoring phosphate concentrations in a sequencing batch reactor system [206] and in human saliva [207]. The enzyme was immobilised by drop-coating a Nation solution onto the working electrode surface this was then covered by a poly(carbamoyl) sulfonate (PCS) hydrogel membrane. 

Figure 4.5 Schematic of two possibilities of monitoring and adjusting temperature in a conventional batch reactor and a micro fluidic device [13] (by courtesy of S. Masebe, Kyoto University).

Control and monitoring of the chemical reactor play a central role in this procedure, especially when batch operations are considered because of the intrinsic unsteady behavior and the nonlinear dynamics of the batch reactor. In order to meet such requirements, the following fundamental problems must be solved ... 

F. Caccavale et al., Control and Monitoring of Chemical Batch Reactors, Advances in Industrial Control,... 

In order to ensure an adequate quality of products and a safe operation, the monitoring of a batch reactor should include, at least, online measurements of temperature, pressure, and of some composition-related variables. In this context, online measurements may be defined as measurements obtained via instruments strictly connected to the reactor and characterize by response times markedly smaller than the characteristic times of the chemical reaction. In general, this is the case of temperature and pressure, which can be easily measured online by means of reliable, relatively cheap, and poorly intrusive sensors. This allows the introduction of sensor redundancy, a common practice to increase reliability. On the other hand, online... 

Due to the level of risk related to highly exothermic chemical processes, sensors for temperature monitoring are often duplicated in batch reactors. Hence, a duplex sensor architecture is assumed. Namely, two temperature sensors (hereafter labeled as Sr, i and. Sr2) providing measurements of Tr, and two providing measurements of 7] (hereafter labeled as Sj,i and 6 2) are assumed to be available. 

This Advances in Industrial Control monograph, Control and Monitoring of Chemical Batch Reactors, by Fabrizio Caccavale, Mario Iamarino, Francesco Pierri and Vincenzo Tufano exemplifies this universality extremely well. The domain of application, the chemical batch reactor, is part of chemical and process engineering the process objectives are safe process operation, minimal energy consumption, and... 

The primary advantages of the batch reactor are simplicity of design, which allows for tremendous flexibility, and integration of the performance equation over time. The simplicity of design, usually a stirred tank, makes operation and monitoring easy for the majority of reactions. The... 

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