Pilot scale reactor operating conditions

Concerning the operation of catalysts under adiabatic conditions, Basini et al. [156] reported the results of methane partial oxidation runs in a pilot-scale reactor operating at high pressure and short contact times, showing stable activity (almost complete conversion of methane and over 90% selectivity to CO and H2) during more than 500 h on-stream. In addition, operability for 20 000 h bench-scale testing has been claimed recently by the same group [157]. 

Pilot-Scale Reactor. Anaerobic digester effluent was obtained from a non-mixed pilot-scale reactor system operated at Walt Disney World, Orlando, FL, and fed an RDF MSW/sludge blend (64). The MSW feedstock was obtained from Baltimore, MD, and the municipal sewage sludge from the Walt Disney World Complex. Fresh effluent samples were sealed under anaerobic conditions and shipped overnight in ice for analysis. 

Table 2 Laboratory and pilot scale reactor description and operating conditions... 

A purchasable cross-flow heat exchanger for application in laboratory-, pilot- and production-scale plants was developed by FZK. By incorporation of a catalyst on the quadratic plates inside the heat exchanger, it can also be used as a catalytic wall reactor. Operating conditions up to 850 °C (stainless steel) and pressures of more than 100 bar are possible, and the specific inner surface area is up to 30 000 m m. The reactors can be obtained in many materials and three different sizes with a maximum flow of 6500kgh (water). Therefore, the reactors can be adjusted for various processes, and all types of catalyst deposition techniques are possible [111]. This reactor has already been applied to the catalytic oxidation of H2 by Janicke et al. [112], for example. 

The catalyst formulations with the optimum activity, identified as being most selective for given industrial conditions, are typically tested at the next level of R D in pilot-scale reactors closely mimicking industrial plant conditions. Pilot tests are mandatory for further optimization of long-term behavior, and in addition reveal minor details of catalyst performance which escape bench-scale testing, i.e. the formation of minor by-products. Pilot reactor tests are performed under industrial operation conditions, i.e. gas hourly space velocities (GHSV) used in... 

Economy of time and resources dictate using the smallest sized faciHty possible to assure that projected larger scale performance is within tolerable levels of risk and uncertainty. Minimum sizes of such laboratory and pilot units often are set by operabiHty factors not directly involving internal reactor features. These include feed and product transfer line diameters, inventory control in feed and product separation systems, and preheat and temperature maintenance requirements. Most of these extraneous factors favor large units. Large industrial plants can be operated with high service factors for years, whereas it is not unusual for pilot units to operate at sustained conditions for only days or even hours. 

The research programme into n-butyl lithium initiated, anionic polymerization started at Leeds in 1972 and involved the construction of a pilot scale, continuous stirred tank reactor. This was operated isothermally, to obtain data under a typical range of industrial operating conditions. 

A pilot scale plant, incorporating a three litre continuous stirred tank reactor, was used for an investigation into the n-butyl lithium initiated, anionic polymerization of butadiene in n-hexane solvent. The rig was capable of being operated at elevated temperatures and pressures, comparable with industrial operating conditions. 

Collect together all the kinetic and thermodynamic data on the desired reaction and the side reactions. It is unlikely that much useful information will be gleaned from a literature search, as little is published in the open literature on commercially attractive processes. The kinetic data required for reactor design will normally be obtained from laboratory and pilot plant studies. Values will be needed for the rate of reaction over a range of operating conditions pressure, temperature, flow-rate and catalyst concentration. The design of experimental reactors and scale-up is discussed by Rase (1977). 

The RC1 is an automated laboratory batch/semi-batch reactor for calorimetric studies which has proven precision. The calorimetric principle used and the physical design of the system are sound. The application of the RC1 extends from process safety assessments including calorimetric measurements, to chemical research, to process development, and to optimization. The ability of the RC1 to generate accurate and reproducible data under simulated plant scale operating conditions may result in considerably reduced testing time and fewer small scale pilot plant runs. 

The choice of appropriate reaction conditions is crucial for optimized performance in alkylation. The most important parameters are the reaction temperature, the feed alkane/alkene ratio, the alkene space velocity, the alkene feed composition, and the reactor design. Changing these parameters will induce similar effects for any alkylation catalyst, but the sensitivity to changes varies from catalyst to catalyst. Table II is a summary of the most important parameters employed in industrial operations for different acids. The values given for zeolites represent best estimates of data available from laboratory and pilot-scale experiments. 

The conversions, selectivities, and kinetics are ideally obtained in a small batch reactor, the operating conditions and catalyst formulation are determined from a bench-scale continuous reactor, the process is tested and optimized in a pilot plant, and finally the plant is constructed and operated. While this is the ideal sequence, it seldom proceeds in this way, and the chemical engineer must be prepared to consider aU aspects simultaneously. 

For the experiments with increased water content or suppressed water removal, a 5 cm-long piece of coated monolith was mounted in a 500-mL autoclave. All liquid concentrations, operation conditions and catalyst hold-up were the same as in the pilot-scale plant. To maintain a gradient-less operation, a turbine-type stirrer recirculated the liquid very rapidly through the monolith channels. During the experiments, liquid samples were taken from the reactor and analyzed as described above. 

This difficulty arises because the size and operating conditions of a large-scale reactor normally differ significantly from that of a pilot-scale column. Commercial hydrodesulfurization reactors are of size up to 20 by 30 ft. and may be operated at up to 70 atmospheres and 400°C. In contrast, pilot-scale hydrodynamic data are obtained from columns of a few inches, or less, in diameter and several feet in height, at near atmospheric pressure and room temperature. 

It is difficult to ascertain whether the poor performance observed in pilot-scale trickle-bed reactors is due either to ineffective catalyst wetting or to the axial dispersion effects, because both these effects are physically realistic and both occur under similar operating conditions (i.e., low liquid flow, large catalyst size, and shorter beds). It should be noted, however, that the criterion for removing the axial dispersion effect is available. A similar criterion for removing ineffective catalyst wetting is, however, presently not available. 

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