Search

In this contribution to the Special Issue honoring 100 very successful years of Casale S.A., we review and critically discuss the current status of modeling the most demanding selective partial oxidation reaction industrially applied: the partial oxidation of n-butane to maleic anhydride. We examine theoretical model descriptions of this partial oxidation reaction covering all relevant length scales: from modeling the active site and elementary steps, microkinetic and macrokinetic models, to reactor models on all length scales from laboratory reactors up to industrial-size production reactors. We also include in our manuscript the latest CFD developments aiming at a better understanding of heat and mass transfer in industrial catalyst beds as well as effects of the local bed structure. The contribution also covers relevant experimental findings with respect to the catalytically active species or sites on the catalyst surface, the reaction mechanism as well as microkinetic considerations. 60 years of research have greatly improved our understanding of the selective partial oxidation reaction. However, a critical review of the different aspects of the n-butane oxidation and its industrially used catalyst reveals on all length scales that there still remain unanswered questions, and that there are still some inconsistencies in our fundamental understanding. This situation arises from the fact that the catalyst for n-butane partial oxidation is a highly complex and dynamic system and its performance depends on all details of its generation and its operational history.

Industry of pyrroles synthesis on the basis of acetylene, ammonia and amines over polyfunctional catalyst can be organised only when for its recovery the rational industrial technology allowing to synthesize this product in necessary quantity and demanded quality cheap enough from accessible raw materials is developed. Considering the issues related to the development of a new reactor with high productivity and economic efficiency, the processes running in the reactor were studied. Phase characteristics have been investigated in response to changes in acetylene conversion rate due to the height of the catalyst layer. As a result, high productivity of acetylene production with zinc-chromaluminum catalyst at the temperature range of 340-440оС is achieved for 92% when the layer height is 1200 mm from the reactor top point. Based on the mass balance as well as the experimental result, a reactor for the industrial synthesis of pyrroles has been proposed.

We propose a numerical methodology to combine detailed microkinetic modeling and Eulerian–Eulerian methods for the simulation of industrial fluidized bed reactors. An operator splitting-based approach has been applied to solve the detailed kinetics coupled with the solution of multiphase gas–solid flows. Lab and industrial reactor configurations are simulated to assess the capability and the accuracy of the method by using the oxidative coupling of methane as a showcase. A good agreement with lab-scale experimental data (deviations below 10%) is obtained. Moreover, in this specific case, the proposed framework provides a 4-fold reduction of the computational cost required to reach the steady-state when compared to the approach of linearizing the chemical source term. As a whole, the work paves the way to the incorporation of detailed kinetics in the simulation of industrial fluidized reactors.

The determination of the physicochemical forms of radioiodine in the gas-air environment of an industrial nuclear reactor is necessary to solve related problems – technological control and radiation safety. In the technological context, the results obtained make it possible to adequately assess the efficiency of purification of emissions of radioactive iodine isotopes, the choice of instruments and methods for controlling emissions. In the context of radiation safety, research results make it possible to correctly assess the radiation effects on the environment and humans, substantiation of emission standards for the atmosphere and confirmation of the safety of operation of an industrial reactor installation. The research method is based on the difference in the deposition of radioiodine on a set of one AFA-RMP aerosol filter and six filters of the AFA-SI type, which makes it possible to separately determine the 131I aerosol, easily and hardly sorbed form. It has been shown that the non-purified gas-aerosol mixture mainly contains radioactive iodine in the form of gaseous hardly adsorbed compounds. For 131I, the most probable percentage in volumetric activity of hardly adsorbed, easily adsorbed compounds and iodine aerosols was obtained. Based on the data obtained, an assessment of dose loads was carried out taking into account the annual emissions of the reactor installation and weather conditions. A conservative approach to assessing the radiation exposure of 131I emissions is 47 times higher than the assessment taking into account its physicochemical forms.

On the basis of the recommendations of the IAEA and the requirements of domestic regulatory documents, a study is conducted to determine the activity of aerosol and gaseous forms of 131I compounds in a gas-aerosol mixture of emission from an industrial reactor facility (hereinafter referred to as IRF). Three types of packs of analytical filters are used as an adsorption-filter material. Under normal operating conditions, a series of sampling procedures is performed at a point in front of the gas cleaning system. The investigations have made it possible to determine the dominant physical form of 131I in the high-pressure gas holder. It is shown that, in a gas-aerosol mixture prior to the IRF gas cleaning system, the volumetric activity of iodine is determined mainly by hardly adsorbed gaseous compounds. The ejector gases contain iodine-131 compounds, which are hardly adsorbed on silver nitrate impregnate. The obtained data will be used in designing the cleaning systems for new IRFs of a similar type.

The design of a reactor developed to process associated petroleum gas for producing hydrogen and nanofibrous carbon material is described. The catalytic pyrolysis parameters, based on which the technological scheme is developed, are chosen. The efficiency of the device for catalyst mixing in the reactor is proved by modeling method.

To counter the equilibrium limitations in traditional methanol production from synthesis gas, a periodic and sorption-enhanced methanol synthesis process (SE-MeOH) with in situ removal of water byproduct is designed and optimized. A generalized reaction–adsorption modeling and simulation framework is coupled with a simulation-based constrained gray-box optimizer to obtain the optimal cycle configuration, design parameters, process specifications, and operating conditions. The best-case results indicate that SE-MeOH processes can break the barrier of the current limit of industrial methanol yield and improve it by 55–87% with a slight compromise (9–46%) on CH3OH production capacity. This trade-off is a result of periodic operation which is required for sorption enhancement. The techno-economic optimization of a base industrial reactor also leads to more than 7% improvement in methanol yield with only 2% decrease in production capacity while keeping the cost of syngas-to-methanol production competitive. The...

A number of potential runaway reaction systems of the fine chemical industry (e.g., polymerization processes) undergo significant changes of their physical properties with the reaction extent, resulting in thickening phenomena of the reaction mass and in a consequent decay of the reactor heat-transfer efficiency. In this work, a set of key process indicators have been developed, allowing for monitoring of safe operating conditions of industrial semibatch polymerization reactors without requiring any kinetic characterization of the reaction system. The only required information are the heat of reaction and some fully available process variables that are normally recorded for any industrial reactor. The proposed criterion has been successfully validated using some experimental data measured on an industrial polymerization reactor for the production of polyacrylic rheology modifiers.

The industrial/chemical reactor is a vital part when chemical production have been widely used in many factories. The material separation followed by the chemical reaction in the industrial reactor is crucial to the quality of product. At present, existing industrial reactor material separations mainly depend on human intervention, that suffers the drawbacks of high cost and low accuracy. In this paper, a novel intelligent image recognition based industrial reactor material separation algorithm is developed. The industrial reactor materials are first captured with a equipped camera and an improved binary color histogram feature extraction algorithm is then developed for image representation. The support vector machine (SVM) is trained as a classifier for material separation. A total of 1522 images of the industrial reactor material belonging to five different categories are collected for performance evaluation. Experiments show that the proposed algorithm is able to achieve an accuracy of 98.36% in the industrial reactor material separation, and outperforms the conventional histogram feature based algorithms.

In the present work, a first-principles model of methanol partial oxidation to formaldehyde in an industrial reactor was developed and the reaction kinetic and deactivation parameters estimated, taking advantage of the temperature profile established by the exothermic reaction. The catalyst deactivation was assigned primarily to hot-spot regions in the oxidation reactor. The exposure to high temperatures enhances solid-state reactions that produce volatile compounds and a consequential loss of catalyst active compounds that migrate downstream from the hot-spot. This phenomenon was modelled implementing a new method where, instead of time, the deactivation was integrated as a function of the total consumed reagent until the instant of interest. This approach allowed computing the activity of the catalyst at any instant without needing to solve the model for the whole operating history until the pertinent instant; for simulating industrial reactors, where the operating conditions are changing frequently, this feature is quite relevant.

The behavior of the RS and XRD characteristics was studied experimentally on the example of a low-ordered nanocarbon material with controlled changes in the parameters of simplified actions or their combinations. The results of research are necessary when studying the nanostructures of such materials in order to optimize them in the development of electrode masses for modern autonomous systems for the production and storage of energy. We used varieties of actions that are similar to technological operations in obtaining carbon black in an industrial reactor. Impacts reduced defectiveness, increased orderliness, changed the orientation of nanographene sheets in the stacking.

International audience; The increased need for protecting cutting tools has led to the development of more and more efficient coatings. Ti-Al-N is one of the most studied systems in the hard coating industry due to the high hardness and good oxidation resistance of Ti1−xAlxN coatings. The development of LPCVD processes has led to the discovery of new microstructures and morphologies. In this study, we discuss the microstructural and morphological changes caused by varying the aluminum content in films deposited by low pressure thermal CVD in an industrial reactor at low carrier gas flow and relatively high pressure (>4 kPa). Coatings were characterized using FE-SEM, XRD and TEM analysis, revealing the growth of nanolamellae with modulated Al and Ti contents for the lowest Al containing coatings. The coatings with the highest Al contents were also found to show particular cube-shaped grains with a micromodulation of composition. Experimental Al content values are higher than the calculated one and their evolutions with the AlCl3/(AlCl3 + TiCl4) molar ratio are similar. The hardness and oxidation resistance were characterized and compared with available data in literature. Higher hardness is obtained for coatings having an Al content up to x = 0.65 and a hardness drop is found for higher Al contents. The oxidation resistance of the coatings rises continuously with an increasing Al content.

Results are presented from tests involving the metallization of extrusion briquettes in an industrial reactor (Midrex process). The brex are made from screenings of oxidized pellets, partially metallized sludge, mill scale, and EAF dust with the use of two types of binders. The effect of the type of binder on the briquettes’ strength and degree of metallization is studied. Optical and electron microscopy are used to examine the structure of green briquettes and briquettes after their reduction.

The performance of an ethylbenzene dehydrogenation industrial reactor was studied for about 800 days and a catalyst deactivation model was derived. The results showed that the proposed model can predict catalyst deactivation significantly better than standard models, with only 2.5% prediction error after 800 days of operation. Moreover, the optimal path for increasing the temperature of the styrene production reactor was introduced for the first time to maximize styrene production.

A mathematical model was developed for two units of industrial fluidized bed reactors equipped with different systems for feeding gaseous feedstock: three toroidal rings with nozzles in unit 1, and a false bottom with nozzles distributed through it in unit 2. Analysis of the efficiency (expressed as the yield of the target product – isobutylene) of the units during 4 month operation under industrial conditions demonstrated a higher efficiency of unit 2. The reasons for the differences in the product yields in two units were found using numerical solutions to obtain characteristic patterns of concentration fields of catalyst particles and temperature fields in the units; the results obtained demonstrated more uniform and dense catalyst distribution and more uniform reactorheating characteristics of unit 2. The constructed patterns of main circulative flows of the catalyst accounted for the considerable differences in the catalyst concentration and gas temperature fields. The numerical solutions were used for comparative analysis of the operation efficiencies of the units to show good agreement with the analytic results on industrial reactors. The proposed approach can be used for the design of new and optimization of operating units.

The prototype of an industrial reactor antineutrino detector iDREAM is constructed to demonstrate the capability of real-time remote monitoring of PWR operation by the neutrino method.

Nodal diffusion is currently the preferred neutronics model for industrial reactor core calculations, which use few-group cross-section libraries generated via standard assembly homogenization. The infinite-medium flux-weighted cross sections fail to capture the spectral effects triggered in the core environment by nonreflective boundary conditions at the fuel-assembly edges. This poses a serious limitation to the numerical simulation of current- and next-generation reactor cores, characterized by strong interassembly heterogeneity. Recently, a spectral rehomogenization method has been developed at AREVA NP. This approach consists of an on-the-fly modal synthesis of the spectrum variation between the environmental and infinite-medium conditions. It uses information coming from both the nodal simulation and the lattice transport calculation performed to compute the standard cross sections. The accuracy of the spectral corrections depends on the choice of the basis and weighting functions for the expansion and on the definition of a realistic energy distribution of the neutron leakage. In this paper, we focus on the first aspect. Two tracks are researched: a combination of analytical functions (with a physically justified mode) and a mathematical approach building upon the Proper Orthogonal Decomposition. The method is applied to relevant pressurized-water-reactor benchmark problems. We show that the accuracy of the cross sections is significantly improved at reasonably low computational cost and memory requirement. Several aspects of the methodology are discussed, such as the interplay with space-dependent corrections. We demonstrate that this approach can model not only the spectral interactions between dissimilar neighbor assemblies but also the spectral effects due to different physical conditions (namely, multiplicative properties) in the environment and in the infinite medium.

This paper presents a computational procedure for producing tailor made polymer resins, satisfying customers’ needs while operating with maximum profit. The case study is an industrial large-scale polymerization reactor. The molecular properties considered are melt index (MI), which measures the molecular weight distribution, and stress exponent (SE), which is related to polydispersity. An economic objective function is associated to a deterministic mathematical model and the resulting optimization problem is solved by genetic algorithm (GA), a stochastic method. The GA parameters for both binary and real codifications are tuned by means of the design of experiments. Attempting to achieve the global optimum, a hybrid method, which introduces process knowledge into GA random initial population, is proposed. The binary codification performs better than the real GA, especially with hybridization. Results show that the GA can satisfactorily predict tailor made polymer resins with profits up to 25% higher than the industrial practice.

The pilot test is an important procedure that ultimately leads to implementation of an optimized catalytic process. A global reaction rate was calculated from the intrinsic kinetic rate with the effectiveness factor, and the calculated value is fitted well with the experimental data, which indicates that the global reaction rate is reliable. Further, a scale-up HCl oxidation experiment has been carried out in a single-tube reactor with an inner diameter of 22 mm using shaped CeO2–CuO/Y as the catalyst. A one-dimensional fixed-bed model based on the global reaction rate was adopted to properly describe the reaction behavior in the single-tube reactor. The results have laid a valuable foundation for the industrial reactor designation and the process optimization of HCl oxidation.

Design of pressure vessels, which are subjected to various natures of loading, must prevent damage mechanisms occurrence. For a load applied or maintained with a given intensity, primary failure modes can appear, such as gross plastic deformation, plastic instability or buckling. For design-by-analysis, the reference methodology is based on an elastic stress calculation. During the last decade, studies have shown that this ingenious procedure could provide conservative design limits. They can become actually overly conservative in a context of increasing complexity of geometry and loading modelling. In parallel, technological and theoretical developments enabled limit analysis to be considered as an interesting design methodology. This is suggested in standards and codes (EN 13445, CODAP, Boiler and Pressure Vessels Code) since the early 2000's. In this first of two companion papers, a set of standardized and innovative procedures is introduced. These approaches rely on various concepts, such as elasticity, incremental elastoplasticity, or elastic compensation (Modified Elastic Compensation Method, Linear Matching Method). Each methodology is presented on theoretical aspects, eventually adapted so as to take into account safety margins. They are then applied on a model inspired from a real industrial reactor, using Abaqus. Results are compared to reference data from codes, in terms of accuracy and computing time. A final assessment underlines practical benefits that could be expected.

The main regularities of the chloroorganic by-products formation in the ethylene oxychlorination process in the fluidized bed catalyst are examined in the round-up article. On the basis of published literature data conclusions about by-products formation by the reactions of dichloroethane dehydrochlorination and partial oxidation are drawing. The increase of the process temperature promotes to the rise of the by-products yield. There is indicated that the use of the catalysts containing cupric chloride and chlorides of alkali or alkali-earth metals helps to reduce of the side reactions part. In the industrial conditions the best results are reached at the use of the catalysts with the not high copper content at the external surface of the granule. The iron penetration to the catalyst due to the erosion of the industrial reactor walls leads side by side with the decrease of the oxychlorination process rate to the increase of the chloroorganic by-products yield.

This study was motivated by the fact that differential scanning calorimetry (DSC)/differential thermal analysis (DTA) results in literature showed significant exothermic peaks while in overall, pyrolysis is an endothermic phenomenon. The specific heat of the decomposing tires has been determined with a new methodology: instead of assuming constant char properties throughout pyrolysis, the specific heat of evolving solids (char) was evaluated with increasing temperature and conversion. Measured specific heat values were observed to increase until pyrolysis was triggered at 250°C. Then, the specific heat of the solids decreased continuously until 400°C at which point they started to increase. This unexpected trend pointed out that the exothermic peak observed with DSC is an artefact generated by the control system of the apparatus. To overcome this limitation, the energy balance was performed over industrial data and the newly found heat capacity values. The enthalpy of pyrolysis was found to have a term dependent on the weight loss derivative, with a constant value of 410 kJ/kg tires. Two other terms for the enthalpy of pyrolysis have been identified, which were independent of weight loss. The first one is believed to correspond to the sulphur cross-link breakage at low temperature (65 kJ/kg), while the second one, at the final stage of pyrolysis, should correspond to charring reactions approaching the thermodynamic equilibrium (75 kJ/kg). Ultimately, this work proposes a new methodology to determine the enthalpy of pyrolysis with larger scale experimental data.

Zeolites are widely used as catalysts and catalyst supports for fuel and lubricants production processes with enhanced performance properties. Design of industrial reactor requires the construction of a mathematical model and selection of optimal operating conditions for reducing the number of scaling stages. The authors have proposed a scheme of hydrocarbons conversion on zeolite catalysts, thermodynamics of reactions has been considered and the inverse kinetic problem has been solved. The model of reactor of straight–run gasoline fractions refining in software HYSYS Aspen Plus™ process simulator has been developed and its adequacy to experimental data has been shown.

The main objective of chemical reaction engineering research is the design and operation of an industrial reactor to conduct chemical reactions more effectively at an industrial scale. Such efforts require knowledge from multiple disciplines and reaction kinetics is one of the most fundamental knowledge needed. In this chapter, based on the knowledge of Physical Chemistry, we will review some fundamental concepts of chemical reaction kinetics and discuss methods and procedures for kinetic analysis. Both homogeneous and heterogeneous catalytic kinetics will be discussed.

This work focussed on the deactivation of molybdenum oxide installed in an industrial methanol oxidation reactor. The deactivation parameters were estimated using the operational data obtained during the entire lifetime of the previously installed catalyst and validated with the results from the new catalyst. The deactivation was calculated as a function of the total reagent consumption instead of time. The results presented a good agreement with the available industrial data and the resulting model will then be used for the description of the whole formaldehyde production process.

This paper uses a network of ideal flow reactors and a detailed population balance model to study the evolution of the size and shape distributions of pigmentary titanium dioxide, formed under industrial synthesis conditions. The industrial reactor has multiple reactant injections, a tubular working zone in which the exothermic reaction is completed, and a cooling zone. A network of continuously stirred tank reactors is used to model variation in composition around the feeds and plug flow reactors with prescribed temperature gradients are used to describe the working and cooling zones. The quality of the industrial product depends on its morphology, and this is influenced by factors including temperature and throughput. In this paper, a multivariate particle model is accommodated using a stochastic method and the particle morphology is characterised in terms of the distributions of primary and aggregate particle diameters, number of primary particles per particle and neck radii of connected primary particles. Increasing temperature or residence time is shown to produce larger particles. Qualitative similarities are highlighted between such findings and previous studies. The throughput studies are also in qualitative agreement with empirical industrial experience. There is scope for extending and improving the current model; however, it is suggested that insights of this type could be used to inform the design and operation of the industrial process. Accepted version

This work addresses heat losses in a CVD reactor for polysilicon production. Contributions to the energy consumption of the so-called Siemens process are evaluated, and a comprehensive model for heat loss is presented. A previously-developed model for radiative heat loss is combined with conductive heat loss theory and a new model for convective heat loss. Theoretical calculations are developed and theoretical energy consumption of the polysilicon deposition process is obtained. The model is validated by comparison with experimental results obtained using a laboratory-scale CVD reactor. Finally, the model is used to calculate heat consumption in a 36-rod industrial reactor; the energy consumption due to convective heat loss per kilogram of polysilicon produced is calculated to be 22–30 kWh/kg along a deposition process.

Gas phase production of polyethylene (PE) results in a powder with particles of different sizes. This experimental work on the samples from an industrial reactor shows that there is a difference between Mw and properties of the PE particles as a function of their sizes. The results showed that for each type of polyethylene there is a critical particle size for which Mw reduces to a minimum. Particle size was found to have strong influence on the rheological behavior of high-density polyethylene (HDPE) homopolymer. The smallest homopolymer HDPE particles showed the highest Mw with distinctly different flow behavior. Differences in properties for HDPE copolymer and linear low density polyethylene (LLDPE) samples were less profound.