Showing papers in "Hungarian Journal of Industrial Chemistry in 2009"

Fuel Purpose Hydrotreating of Vegetable Oil on NiMo/γ-Al2O3 Catalyst

Abstract: The application of biofuels has become more important in the whole world since the last decades. Intensive research has been started for the production of biofuels which can be applied in Diesel engines and has different chemical composition from the previously used ones. Among these fuels the most important one is biogasoil (normal and iso-paraffins) produced from triglycerides with catalytic hydrotreating (special hydrocracking). The aim of present study was to investigate the applicability of commercial NiMo/γ-Al2O3 catalyst for conversion of specially pretreated Hungarian sunflower oil to produce motor fuel components. The change in the hydrotreating activity of applied catalyst, the pathways of hydrodeoxigenation reactions and the effect of process parameters (T=300–360 °C, p=20–60 bar, LHSV=0.5–2.0 h-1, H2/sunflower oil volume ratio: 400 Nm3/m3) on the yield and composition of the products were also investigated. It was concluded that on the investigated NiMo/γ-Al2O3 catalyst products with relatively high (>50%) paraffin content (T=360–380 °C, p=60 bar, LHSV=0.5–1.0 h-1) could be produced. The yield of the produced target fraction was 50.7–54.5% at these advantageous process parameters. So it is necessary to separate and recirculate the heavy fraction. In case of every investigated process parameter C18-, C17-, C16- and C15 normal paraffins were formed, i.e. both the HDO and the decarboxylation/ decarbonylation reactions took place. The cetane number of the target fractions, are very high (>80, EN standard: ≥51), but the cold flow properties of this fraction are disadvantageous. To improve this disadvantageous property it is necessary to carry out selective isomerization of the target fraction.

Dynamic model and control of heat exchanger networks for district heating

Abstract: The various governmental policies aimed at reducing the dependence on fossil fuels for space heating and the reduction in its associated emission of greenhouse gases such as CO2 demands innovative measures. District heating systems using residual industrial waste heats could provide such an efficient method for house and space heating. In such systems, heat is produced and/or thermally upgraded in a central plant and then distributed to the final consumers through a pipeline network. In this work two main objectives will be considered: the first is to create a dynamic model which can represent the main characteristics of a district heating network and the second one is to design a non-linear model predictive controller (NLMPC) to satisfy the heat demands of the consumers in the heat exchanger network. As the model predictive controller is based on minimizing an objective function, it is totally perfect to find the way to reduce the superfluous energy consumption and make the best of using the freely applicable industrial waste heats. Beside this environmental aspect, reducing the invested energy consumption can reduce the operational costs.

Mathematical Modeling of Diafiltration

Abstract: The main objective of this study is to provide a general mathematical model in a compact form for batch diafiltration techniques. The presented mathematical framework gives a rich representation of diafiltration processes due to the employment of concentration-dependent solute rejections. It unifies the existing models for constant-volume dilution mode, variable-volume dilution mode, and concentration mode operations. The use of such a mathematical framework allows the optimization of the overall diafiltration process. The provided methodology is particularly applicable for decision makers to choose an appropriate diafiltration technique for the given separation design problem.

Comparison of Calibration Models Based on Near Infrared Spectroscopy Data for the Determination of Plant Oil Properties

Abstract: The aim of this study was to compare the prediction efficiency of different type of linear calibration models using near infrared (NIR) absorbance spectral data of vegetable oils. The applied model types were the PCA-MLR (principal component analysis-multiple linear regression), the PLS (partial least squares regression), the PCA-ANN (principal component analysis-artificial neural network) and the GA-ANN (genetic algorithm-artificial neural network). The calibrations were executed on the models for the determination of the concentration of oleic acid of vegetable oils and the performances of the different models were determined using external validation. During external validation the built models were tested with vegetable oil samples of which oleic acid content was known and was not included in the calibration sample set. The comparison of the models was executed on the basis of the accuracy of the prediction.

Comparison of the Structure and the Stability of Single Enzyme Nanoparticles

Abstract: Single enzyme complex nanoparticles were synthesized following the method of Kim et al. The enzyme complex used was cellulosome that is a large spatial association of enzymes. Single enzyme nanoparticle of celluclast BG cellulase enzyme complex (SEN-CK) can degrade as great substrates as natural cellulose. It was proved that the stability of SEN-CK enzyme complex is significantly better than that of native enzyme complex (enzyme without pretreatment). Significant portion of the activity of SEN-CK is remaining at 80 °C for 1 hour time.

Preparation and Characterization of ZnO and TiO2 Sol-Gel Thin Films Deposited by Dip Coating

Abstract: ZnO and TiO2 thin films were prepared by sol-gel technique. Dip coating was applied for film deposition and withdrawal velocity was varied in order to control the film thickness. The deposited films were annealed to remove additives and obtain oxide layers. Large silicon and glass substrates were coated with homogeneous, reflective semiconductor layers of different refractive index values. UV-Vis spectroscopy and scanning angle reflectometry measurements were performed to determine refractive index and thickness values. The using of different stabilizers for ZnO precursor sol preparation resulted in different layer thicknesses and very different response to the varying of the withdrawal speed. According to photoluminescence measurements ZnO films are of good crystallinity. Thicknesses of deposited films were found to be in the range of 6-200 nm. TiO2 coatings show strong interference colours due to their high refractive index.

PCA Driven Similarity for Segmented Univariate Time Series

Abstract: Selection of the proper similarity measure is the cornerstone of all time series data mining task. In the recent years, many similarity measures have been introduced to fulfill the needs of chemical process engineering. These measures have been guided by data reduction methods due to the large amount of data. This data reduction can be done explicitly (by segmentation) as well as implicitly (by utilizing the latent variable space). Usually, the original multivariate data is projected into a single dimension with Principal Component Analysis (PCA) and segmentation is executed. However, the similarity measures which have been used to compare univariate, segmented representations of the original processes do not consider that the main information carried by the univariate representations is the correlation of the original variables. This paper introduces a PCA inspired similarity measure for these univariate segments. Finally, it is shown that the presented method can be considered as the logical extension of the Correlation Based Dynamic Time Warping (CBDTW) to univariate time series.

Synthesis and Evaluation of Modified Polyethylene Wax Applied as Dispersant in Rubber Bitumen Composites

Abstract: Grain rubber obtained from waste tyre has become one of the most important bitumen modifiers nowadays, but rubber precipitation from bitumen can cause problems during utilization. In our experimental work additives were synthesised as dispersant for rubber bitumen composites. Raw material was polyethylene wax (PEW) obtained from mild thermal cracking of polyethylene waste. The synthesis was a copolymerisation of olefins and maleic-anhydride. During the products evaluation the main analytical method was Fourier transform infra-red (FT-IR) spectroscopy. There were significant differences between the characteristic of raw material and synthesised products. The dispersant effect of the additives was studied in rubber-bitumen composites. All additives increased the stability of rubber-bitumen composites. From the results of the experiments it was stated that the modified polyethylene wax obtained from polyethylene waste can solve the instability problem of rubber-bitumen composites.

Examination of the Use of Support Materials of Natural Origin in Wastewater Treatment

Abstract: Wastewater has become continuously concentrated since 1990 in Hungary as the price of drinking water started to increase intensively from that year. Adding to that, reject water, leakages from landfills, and technological effluents of meat waste processing resulted in high specific nitrogen removal requirements at waste liquids of low COD/TKN ratio. Separated treatment of such waste streams is strongly recommended. We applied zeolite and alginite (supporting materials of natural origin and low price) in three parallel experiments to examine their effects on nitrogen removal using synthetic wastewater in these trials. First we measured the efficiency of a cyclically aerated biofilter (zeolite bed). Then we studied the efficiency of an AS SBR (zeolite powder containing activated sludge unit, operated as sequencing batch reactor), finally we substituted zeolite with alginite. The last one has not been examined for improving nitrogen removal in wastewater treatment in our country till now. We tested the three versions parallel with their proper controls. That is why one of the reactors always contained the seeding activated sludge exclusively to compare the effect of the subsidiary component (zeolite/alginite). The best results were received with using zeolite to the activated sludge. It improved both nitrogen removal and sludge settling. Addition of alginite to the AS also considerably improved sludge settling even at low dosages; therefore further pilot plant controls are recommended before any industrial application of the two support material.

Structural Analysis of Process Models Using Their Representation Graph

Abstract: A graph-theoretical method for the structural analysis of dynamic lumped process models described by differential and algebraic equations (DAEs) is applied in this paper in order to determine the most important solvability properties (degree of freedom, structural solvability, model decomposition, dynamic degree of freedom, differential index, e.g.) of these models by using the so-called dynamic representation graph. The structure of the dynamic representation graph is suitable for the determination of the mentioned solvability properties. The most common methods in the modelling practice for the construction of models of complex systems are the union of submodels and hierarchical modelling. Our goal is to investigate the effect of the model union to the solvability properties, especially to the differential index. We show how the representation graph of a complex model can be built up from the representation graphs of submodels. The effect of the structure of submodels and their joining points to the structure of the complex graph and the conclusions drawn from the complex graph structure to the solvability properties are also investigated. The representation graph of the complex model can be easily built up from the representation graphs of the simple models according to the linking of the technological subsystems. If one of the submodels has greater than one differential index then the under and overspecified subgraphs referring to this higher index can be found in the representation graph of the complex model, too. The change in the relative position of the underspecified and the overspecified subgraphs has an effect to the value of differential index. If these subgraphs move further from their original positions the value of the differential index increases. If their relative positions do not change during the built up process then the value of the differential index of the complex system is equal to the value of the differential index of the subsystem having the higher value.

Fuel Production from Triglycerides Containing Gas Oils

Abstract: Lately the development and the use of energy sources which are of bio-origin are required. The engine fuels have special importance. Based on their origin they can be conventional, alternative or conventional + alternative. Biofuels which can be produced from biomass, thus from a renewable energy source, are alternative fuels. The objective of our research work was to investigate the production of diesel fuel with excellent quality and/or of diesel fuel blending component by heterogeneous catalytic conversion of gas oil fraction containing 75% sunflower oil. Furthermore, our aim was to determine the advantageous process parameters (temperature, pressure, liquid hourly space velocity, hydrogen/hydrocarbon ratio) during application of the selected NiMo/Al2O3 catalyst. Based on the results obtained we determined that the main properties of these products were significantly better compared to the feed as diesel fuel components. The products which were made under desired combination of process parameters (T=350–380 °C; p=80 bar; LHSV=1.0–1.5 h-1; H2/feed ratio: 600 Nm3/m3) had lower than 10 mg/kg sulphur and nitrogen content, and the cetane numbers were significantly higher than it is specified in the MSZ EN 590:2009 standard (minimum 51).

Probability and Expected Time of Emptying of Intermediate Storages under Stochastic Operation

Abstract: A mathematical model for the operation of an intermediate storage under stochastic operational conditions is presented. The material input of the storage occurs at randomly, both in terms of time and amount of material, while the output is of constant volumetric rate. The main practical question is the required initial amount of material in the storage allowing no emptying of storage. In order to determine that we define a two variable function. We develop an equation satisfied by this function and present solution for the case of Erlang(n) distributed inter-arrival time. We provide numerical examples and apply this function for solving the original problem.

Investigation of Hydrogenation of Aromatic Hydrocarbons on Pt/Pd/USY Catalyst

Abstract: In this paper the aromatic reduction of gas oils and the conversion of several hydrocarbon groups in the conditions of hydrodearomatization were investigated on Pt/Pd/USY catalyst. It was concluded that in case of hydrodearomatization of gas oils cycloparaffin hydrocarbons (naphthenes) were key components, i.e. the practical process parameters of hydrodearomatization in case of a defined catalytic system (catalyst, feed, etc.) is that where the concentration of naphthenes have a maximum value. In case of this the deep hydrodearomatization and further deep heteroatom reduction can be carried out with maximum yield of gas oil. It was additionally determined that in the condition of hydrodearomatization mainly isoparaffins are formed via ring opening of naphthenes, the rate of increase of n-paraffin concentration is slower, i.e. the decadence of cold flow properties of reduced aromatic containing products are less beside the high cetane number. Therefore the gas oil products can be applied as winter quality diesel fuel blending components.

Production of Bio-Isoparaffins by Hydroisomerisation of Bioparaffins

Abstract: The importance of biofuels becomes more acute, especially in the European Union. Beside them, those second generation products are spreading increasingly which have better product and performance properties relative to the first generation biofuels. The bio gas oil is a promising product that is a fuel with high isoparaffin content in the gas oil boiling range, which can be produced by the catalytic hydrogenation of different triglycerides. In this paper the isomerisation of an intermediate product with high n-paraffin content was studied on SAPO-11 catalyst at 300–360 °C temperature, 20–40 bar pressure, 1.0–3.0 liquid space velocity and 400 Nm3/m3 H2/feed ratio. During the experiments we succeeded to produce an excellent quality diesel gas oil blending component with high i-paraffin content which is practically free of heteroatom content. This product satisfies with some addition all the requirements of the European diesel fuel standard.

Examination of Crystallization Coupled to the SMB-LC Process

Abstract: The simulated moving bed preparative liquid chromatography (SMB-LC) technique is a highly promising method for optical isomer separation. Optimal coupling of SMB-LC to crystallization respectfully increases the effect of enantioseparation. Extract and raffinate products enriched by SMB-LC are suitable for further process by evaporation, cooling crystallization. Chromatographic packing and eluent system selection being the best for the separation and determination of optimal working parameters of SMB-LC coupled with crystallization can be found in our previous publications. The goal of this paper was the detailed study of crystallization process, investigation of crystallization kinetics, such as sample concentration, composition, cooling speed and end-cooling temperature, application of pure seeding crystals with particular influence on the mass and composition of crystals.

Enzyme Facilitated Enantioselective Transport of (L)-Lactic Acid through Membranes

Abstract: Production of ethyl lactate in esterification reaction by candida antarctica lipase enzyme was studied The optimal conditions of the synthesis of ethyl lactate was obtained to be: 20 μl/ml lactic acid, 160 μl/ml ethanol, 15 mg/ml Novozym 435 lipase enzyme. The yield obtained is over 90% and the enantiomeric exess is about 20% at temperature of 40 °C in case of 24 hours reaction time under 150 rpm revolution rate . In the present study, the enantioselective transport of the (L)-enantiomer from racemic lactic-acid has been presented through a lipase-facilitated supported liquid membrane (SLM) containing ionic liquids.

Investigation of Modified PIB-Succinimides in Low SAPS Engine Oils

Abstract: Along with the ever stricter economical, technical and mainly environmental regulations new types of low phosphorus, sulphur and metal containing multifunctional lubricant additives are required for formulating so-called low SAPS (Sulphated Ash, Phosphorus and Sulphur) engine oils. In the greatest volume dispersant additives, mainly polyisobuthylene-succinimide types are used in the formulation of engine oils. By structural modification of the dispersants with molybdenum and sulphur containing compounds advantageous complementary effects could be achieved along dispersant efficiency. Various modified PIB-polysuccinimides with complementary antifriction and antiwear (AF/AW), viscosity-index improver and enhanced detergent-dispersant properties were synthesized and investigated both in base oil and engine oil compositions. The detergent-dispersant and the high temperature deposit preventing effects, thermal- and oxidation stability, AF/AW properties and seal compatibility were studied in fully formulated, low SAPS engine oils with reduced zinc-dialkyl-dithiophosphate (ZnDDP) content. Based on the results it was found that by using suitable additive concentrations the conventional dispersant can be advantageously combined or replaced with these new additives to enhance the properties and to reduce the ZnDDP concentration level of the experimental engine oils.

New Results on the Field of “White Biotechnology”

Abstract: “White biotechnology” term is used to describe the production of chemical compounds by enzymatic or microbial (biotechnological) methods. Our research group focuses on the field of glycerol utilization and lactic acid production, and in this work we present a new kinetic model based on our laboratory lactic acid experiments, and used for planning continuous fermentation with high productivity.

Differences between Optimum Flow Sheet Solutions Obtained by Different Economic Objective Functions

Abstract: This paper discusses the shapes of cash flow functions obtained by modelling chemical processes at different levels of complexity, and the influence of these shapes on optimal solutions obtained by different economic objective functions. Cash flow functions can be unimodal (with maximum) or monotonically increasing (concave) with respect to capital investment. This depends on the quality of major trade-offs established in the model. Unimodal shape is common for modelling with simple and aggregated models, where increasing the investment above certain level causes loss to a project, which indicates improper or insufficient trade-offs in the model. Monotonically increasing concave cash flow functions are usually obtained by using more detailed models. This implies better trade-offs in the model as increasing the investment always brings some benefit (higher or lower). Example of methanol process synthesis presented in the paper indicate that models with monotonic cash flow functions produce significantly different optimal solutions when optimizing different economic criteria, e. g. the net present value, the profit and the internal rate of return. On the other side, the optimal solutions of models with unimodal functions are similar. These results suggest that models should be formulated at the level of complexity which produces monotonically increasing cash flow functions.

Integration of Process Simulators in Advanced Process Control Solutions

Abstract: This paper presents a novel approach to test and to pretune advanced controllers to reduce the onsite work of control engineers and to train operators using advanced control solutions. Following the proposed approach a simulation framework has been developed where detailed process model realized in Matlab which is connected via OPC (Object-Linking and Embedding for Process Control) to the Profit Controller of Honeywell. With the application of the resulted simulation system the model predictive control (MPC) of a nonlinear crystallizer has been analysed. The case study demonstrates the efficiency of the proposed approach and the illustrative results show that the linear and robust MPC is an adequate controller of nonlinear crystallizers.

Mathematical Models for a Closed-Circuit Grinding

Abstract: New continuous and discrete mathematical models are elaborated for describing some types of closed-circuit grinding mill-classifier systems. Based on the discrete model computer simulation is also developed for investigation of grinding processes. The starting point in developing the model is the continuous grinding equation for the open-circuit grinding which is a partial integro-differential equation describing axial mixing and breakage of particles in the grinding mill. The convective flow in the mill is modeled as particle size-dependent process. The boundary conditions at the inlet and outlet of the mill, the initial conditions, and the equations describing the operation of the classifier and its mass balance are the additional equations of the model. The properties and capabilities of the new computer model are demonstrated and analyzed by simulation developed in Matlab environment. The effects of all parameters of the grinding process, among others of parameters of the classifier, are studied via simulation. The main statistical characteristics of the steady states, the hold-up of the grinding device and the operation of the classifier are also studied. The models presented appear to be very flexible and useful tools for analysis and design of closed-circuit grinding processes, and are suitable for the deeper understanding of the aimed processes.

Immobilized Enzymes Availability for Glycerol – 1,3 Propanediol Bioconversion

Abstract: The increasing abundance of glycerol, its renewability, and attractive pricing make it an appealing platform chemical. Glycerol can be utilized in various ways of biological transformation to industrially valuable products. There are some important derivatives among these such as 3-hydroxypropionaldehyde ((3-HPA) commercial name: reuterin), dihydroxyacetone (DHA), and 1,3-propanediol (PDO). PDO has the largest potential need. Several bacteria are able to ferment glycerol to PDO under anaerobic conditions. A new recombinant technology was worked out with the leadership of DuPont and Genecor in the last decade, in which a recombinant Escherichia coli converts glucose directly to PDO. Microbiological production of a molecule has always lower yield than an enzymatic method and usually produces a lot of by-products that can be avoided using enzymatic bioconversion. For years we have been working on a new enzymatic process in order to produce PDO and DHA simultaneously from glycerol. For this enzymatic way three key enzymes are needed: Glycerol-dehydratase (GDHt), 1,3-propanediol-oxydoreductase (PDOR), glycerol-dehydrogenase (GDH). These enzymes must be produced by microbial fermentation. We would like to present the results of developing the fermentation media in economic aspect. Our pleriminary results (not publicated) indicated that the 2xYT medium is perfect for our Clostridium strain. However in economic aspect the concentrations of yeast extract and bactotryptone are too high to scale-up this fermentation procedure. The first purpose of this study was to optimize the fermentation media. Optimized media concentrations are yeast extract, 6 g∙l-1 and bactotryptone, 2 g∙l-1 (instead of 10 and 16 g∙l-1 respectively). The other aim of our work was to develop immobilized enzymes suitable for glycerol to propanediol bioconversion and develop a method to measure the immobilized enzymes activity. We tried a covalent method applying chitosan matrix activated with glutaraldehyde. Chitosan – a natural polyaminosaccharide obtained from chitin – was chosen as support material to bind the three key enzymes from the crude enzyme solution. We could detect that PDOR and GDH enzyme bind to chitosan beads. Immobilized enzymes activity was higher than of the soluble enzymes.

Product Composition Control of a New Batch Pressure Swing Rectifying System

Abstract: When operating the Double Column Batch Stripper (DCBS) configuration the liquid composition of the common vessel of the two columns must be kept between the two azeotropic compositions by affecting the flow rates of the two products. These can be varied by changing the reboil ratio and/or ratio of division of the liquid flow leaving the common vessel. The goals of this paper: - to propose and study a simple control scheme with PID parameters (providing good quality of control) for the new configuration, - investigation of the influence of the liquid division ratio, - determination of optimal value of liquid division ratio (providing the prescribed separation with minimal specific energy consumption). The calculations were made for a minimum (n-pentane – acetone) azeotropic mixture by using a professional dynamic simulator (CCDCOLUMN). By the aid of a PID controller we modified the flow rate of the bottom products (affecting the reboil ratios of the columns). We investigated the action of the control loops and the system for two different set points. In the first case the composition of the bottom products, in the second one – most common in the industry – the bottom temperatures were kept constant.