Sándor Németh

Modelling and simulation of suspension polymerization of vinyl chloride via population balance model

Abstract A detailed population balance model is presented for suspension polymerization of vinyl chloride in an isothermal batch reactor perfectly mixed on macrolevel. Coalescence and breakage of monomer droplets, as well as mass exchange of species between the droplets induced by collisions, termed micromixing, are also included into the model forming a complex three-scale system. The resulted population balance equation is solved by coupling the deterministic continuous time computation of polymerization reactions inside the droplets with the random coalescence and breakage events of droplets using Monte Carlo simulation. The results obtained by simulation revealed that aggregation, breakage and micro-mixing of species induced by droplet collisions affect the process significantly.

Modeling and simulation of suspension polymerization of vinyl chloride via population balance model

Abstract A population balance model is presented for suspension polymerization of vinyl chloride (VC) in an isothermal batch reactor perfectly mixed on macrolevel. Coalescence and breakage of monomer drops, as well as mass exchange of species between the drops induced by collisions, termed micromixing, are also included into the model, forming a complex three-scale system. The resulted population balance equation is solved by coupling the deterministic polymerization reactions inside the drops with the discrete coalescence and breakage events of drops using Monte Carlo (MC) simulation. The results obtained by simulation revealed that the coalescence, breakage and micro-mixing of species induced by drops collisions affect the process significantly.

Disappearing scales in carps: Re-visiting Kirpichnikov's model on the genetics of scale pattern formation

The body of most fishes is fully covered by scales that typically form tight, partially overlapping rows. While some of the genes controlling the formation and growth of fish scales have been studied, very little is known about the genetic mechanisms regulating scale pattern formation. Although the existence of two genes with two pairs of alleles (S&s and N&n) regulating scale coverage in cyprinids has been predicted by Kirpichnikov and colleagues nearly eighty years ago, their identity was unknown until recently. In 2009, the ‘S’ gene was found to be a paralog of fibroblast growth factor receptor 1, fgfr1a1, while the second gene called ‘N’ has not yet been identified. We re-visited the original model of Kirpichnikov that proposed four major scale pattern types and observed a high degree of variation within the so-called scattered phenotype due to which this group was divided into two sub-types: classical mirror and irregular. We also analyzed the survival rates of offspring groups and found a distinct difference between Asian and European crosses. Whereas nude × nude crosses involving at least one parent of Asian origin or hybrid with Asian parent(s) showed the 25% early lethality predicted by Kirpichnikov (due to the lethality of the NN genotype), those with two Hungarian nude parents did not. We further extended Kirpichnikovs work by correlating changes in phenotype (scale-pattern) to the deformations of fins and losses of pharyngeal teeth. We observed phenotypic changes which were not restricted to nudes, as described by Kirpichnikov, but were also present in mirrors (and presumably in linears as well; not analyzed in detail here). We propose that the gradation of phenotypes observed within the scattered group is caused by a gradually decreasing level of signaling (a dose-dependent effect) probably due to a concerted action of multiple pathways involved in scale formation.

Simultaneous validation of online analyzers and process simulators by process data reconciliation

We present a model based algorithm for simultaneous validation of online analysers and process simulators. Reconciled on-line and historical process data satisfying balance and model equations provides the opportunity to validate and improve process models and soft sensors. Accurate simulation results and laboratory measurements can be used for the validation of online analysers. Validated and reconciled data can be used to the iterative and interactive identification of the unknown parameters of the simulator, e.g. for the determination of kinetic parameters. This method can also be used for monitoring and diagnostics of complex processes because situations when the operating conditions have been significantly changed can be discovered. The approach is illustrated by the analysis of an industrial hydrogenation system. We present the proposed iterative and interactive procedure of model development and analyser validation, the applied data reconciliation method, and the details of the case study. The results show the applicability of the proposed scheme in industrial environment and the benefits of the extracted information in the maintenance and monitoring of advanced model based process engineering tools. The developed tool can increase operating efficiency that is the key of reducing energy consumption and environmental impact. This is especially true in hydrocarbon industry where the operation of the technology is supported by process simulator and on-line analyser based advanced process control systems.

Description of raabeia, synactinomyxon and neoactinomyxum developing stages of myxosporeans (Myxozoa) infecting Isochaetides michaelseni Lastočkin (Tubificidae) in Lake Balaton and Kis-Balaton Water Reservoir, Hungary

Molecular and morphometric investigations were conducted on the actinosporean morphotypes of myxosporeans surveyed in oligochaetes of Lake Balaton and Kis-Balaton Water reservoir. Oligochaetes belonging to the species Isochaetides michaelseni Lastočkin and Branchiura sowerbyi Beddard as well as to the genera Nais Dujardin, Dero Müller and Aeolosoma Ehrenberg were studied during an 18-month period. Actinosporeans were obtained exclusively from I. michaelseni (7,818 specimens) with very low prevalence (0.01–0.06%). Four new actinosporean morphotypes of the collective groups raabeia (2 types), synactinomyxon (1 type) and neoactinomyxum (1 type) were found and described, including the first synactinomyxon collective group from Hungarian biotopes and a new raabeia morphotype. Except for Synactinomyxon type 1, the 18S rDNA analysis revealed that the spores did not match any myxospore entity found in the GenBank.

Process modeling and simulation for optimization of operating processes

Abstract During the last decade, a major shift has begun in chemical industry, since there is an urgent need for new tools that are able to support the optimization of operating technologies. This trend is driven by the new tools of information technology. Approaches of this shift differ from company to company but one common feature is that communication between design, manufacturing, marketing and management is centered on modeling and simulation, which integrates not only the whole product and process development chains, but all the process units, plants, and subdivisions of the company. These approaches are under continuous development. Among the wide range of possible improvements, this paper focuses to two frequent imperfections: (i) developed and refined process models are used only in advanced process control system (APC) integrated into distributed control system (DCS) and operator training systems (OTS), and not for detailed analysis and optimization, and (ii) optimal process operating points of these chemical plants are adjusted only at the design and test phase of a new technology, but optima moves with time, new catalyst system, lower price of reactants, claim for new or higher purity products, etc. The aim of this paper is to review, how to manage process optimization, and to show our process simulator based on the chemical engineering model of the technology. This paper will present a case study to demonstrate the technological and ecological benefits of the analysis and optimization of an operating multi-product polymerization plant. The models of advanced process control system (APC) and reactor cascade were implemented in MATLAB® Simulink® environment, as a powerful and popular dynamic simulator.

Synergy between data reconciliation and principal component analysis in energy monitoring

Monitoring of energy consumption is central importance for the energy-efficient operation of chemical processes. Fault detection and process monitoring systems can reduce the environmental impact and enhance safety and energy efficiency of chemical processes. These solutions are based on the analysis of process data. Data reconciliation is a model-based technique that checks the consistence of measurements and balance equations. Principal component analysis is a similar multivariate model based technique, but it utilises a data-driven statistical model. We investigate how information can be transferred between these models to get a more sensitive tool for energy monitoring. To illustrate the capability of the proposed method in energy monitoring, we provide a case study for heat balance analysis in the wellknown Tennessee Eastman benchmark problem. The results demonstrate how balance equations can improve energy management of complex process technologies.

Analysis of separation possibilities of multicomponent mixtures

Abstract Rectification is the most often used fluid separation technology in the chemical industry. The improvement of the distillation equipments and processes are important because of their incidence and their huge energy needs. Recently systematic synthesis of separation sequences is developed significantly. This paper presents a case study of a separation of the multicomponent cracked gas. Those rules of the separation sequence synthesis, were emphasized that are based on the actual example and can be generalized. The generalized rules and the separation structure developed applying generalized rules unambiguously depend on the thermodynamics properties of multicomponent mixture and the specification of the products.

Modelling of divided wall column

The rectification is the most often used fluid separation technology. The improvement of the distillation equipment and process is significant (Haddad and Manley, 2008) because the rectification has relatively low energy efficiency. In practice, the aim is the separation of the multi-component mixture. This task can be solved with a number of columns depending how many components there are or one column with side product(s). This paper focuses on how to find a better structure with minimal energy consumption. The divided wall column (DWC) system is a promising energy-saving alternative for separating multi-component mixtures (Serra et al, 1999). The innovation of this equipment is a wall which divides the space in of the tower so the feed and the side stream-product zones are separated. This wall prevents contamination of the side stream by the feed stream. The dividing wall column has greater efficiency than common column sequence (Hernandez et al V, 2006). The conventional columns with side stream are also convertible to DWC. In this paper different constructions of the DWC were investigated with simulation experiments. The structure of the column was implemented in Aspen Plus TM simulator using the Radfrac unit of the software. The effects of the main parameters of the divided wall column like split ratio of the liquid and vapor stream, height of the wall, vertical position of wall, and the heat transfer of the wall were analyzed.

Integrated process and control system model for product quality control-application to a polypropylene plant

In the near future of chemical industry, communication between design, manufacturing, marketing and management should be centered on modeling and simulation, which could integrate the whole product and process development chains, process units and subdivisions of the company. Solutions to this topic often set aside one or more components from product, process and control models, hence, as a novel know-how, an information system methodology was developed. Its structure integrates models of these components with a process data warehouse where integration includes information, location, application and time integrity. It supports complex engineering tasks related to analysis of system performance, process optimization, operator training systems (OTS), decision support systems (DSS), reverse engineering or software sensors (soft-sensors). The case study in this article presents the application of the proposed methodology for product quality soft-sensor application by on-line melt index prediction of an operating polymerization technology.