Swelling of plant material under the influence of supercritical carbon dioxide – mathematical modelling and optimization of the process of supercritical fluid extraction

Tema ove doktorske disertacije je ispitivanje bubrenja biljnog materijala pod uticajem natkritičnog ugljenik(IV)-oksida, kao i efekata koje bubrenje ima na proces natkritične ekstrakcije (NKE). Na rezultate eksperimenata u kojima je praćena kinetika procesa NKE primenjen je matematički model na nivou sekrecione strukture i model Sovove, kako bi se promene do kojih dolazi usled bubrenja biljnog materijala kvantitativno izrazile preko parametara modela. Ispitano je bubrenje glandularnih trihoma biljaka familije Lamiaceae, bubrenje hmelja u vidu mlevenih čestica biljnog materijala i industrijskih granulata, i bubrenje čestica korena odoljena i rizoma đumbira. Ispitivanja su vođena u pravcu optimizacije procesa NKE u odnosu na potrošnju natkritičnog fluida i energije. Za proces NKE etarskih ulja iz glandularnih trihoma razvijen je kompleksan matematički model koji uključuje raspodelu vremena pucanja glandularnih trihoma, koji opisuje proces NKE sa znatno većom tačnošću u odnosu na postojeće matematičke modele. Za ekstrakciju na višim pritiscima definisan je optimalan predtretman biljnog materijala kojim se postižu značajne uštede natkritičnog fluida. U slučaju bubrenja hmelja razmatrani su fenomeni prenosa mase u šišaricama i granulatima hmelja izloženim natkritičnom fluidu na različitim uslovima. Rezultati su objasnili pojave koje se dešavaju na industrijskom nivou, a pre svega nepoželjno očvršćavanje ekstrakcione pogače. Parametri procesa (koeficijenti difuzije kroz čvrstu fazu) opisani su primenom matematičkih modela na eksperimentalne rezultate. U slučaju bubrenja korena odoljena i rizoma đumbira, izborom optimalnog predtretmana ostvarene su značajne uštede natkritičnog fluida. Parametri procesa (koeficijenti prenosa mase kroz čvrstu fazu) opisani su primenom matematičkih modela na eksperimentaln rezultate.The subject of this disertation is the swelling of plant material under the influence of supercritical carbon dioxide, as well as the effects of swelling on the process of supercritical fluid extraction (SFE). The results of experiments on the kinetics of the SFE processes were modeled using a mathematical model on the micro-scale and the Sovova’s model, which quantitatively express, through the parameters of the model, the changes that occur due to the swelling of plant material. The swelling of glandular trichomes of plants of the Lamiaceae family, swelling of hop in the form of ground particles of plant material and industrial granulates, and swelling of the particles of valerian root and rhizome of ginger were observed. The tests were conducted in order to examine the possibility of optimization the SFE process in respect to the consumption of supercritical fluids and energy. For the process of SFE of essential oils from glandular trichomes, a complex mathematical model which includes the cracking time distribution for glandular trichomes was developed. The new model describes the process of SFE with significantly higher accuracy than the existing mathematical models. For extraction at higher pressures the optimal pretreatment of plant material is defined with the goal to achieve significant savings of supercritical fluid. In the case of swelling of hops, the mass transport phenomena in granulates and cones exposed to supercritical fluid in various conditions were considered. The results explained phenomena that occur on industrial scale, especially undesirable hardening of the extraction cake. Process parameters (diffusion coefficients in the solid phase) are described by applying mathematical models to experimental results. In the case of swelling of valerian root and rhizome of ginger, significant savings of supercritical fluid consumption were achieved by choosing the optimal treatment. Process parameters (coefficients of mass transfer through the solid phase) are described by applying mathematical models to experimental results

Implementation of energy management system In final energy consumption sectors in republic of Serbia

Ugalj, nafta i gas, uljni škriljci i obnovljivi izvori energije predstavljaju energetski resurs Republike Srbije. Udeo kvalitetnijih energenata kao što su nafta i prirodni gas iznose manje od 1% geoloških razervi, dok preostalih 99% čine različite vrste ugljeva sa najvećim udelom lignita od preko 95%. Procenjeni ukupni tehnički raspoloživ potencijal obnovljivih izvora energije u Srbiji iznosi 5,65 Mten, od čega se 1,054 Mten biomase i 0,909 Mten hidroenergije već koristi. Kada se govori o efikasnom korišćenju energije u finalnim sektorima potrošnje, Srbija ima nezavidan položaj u odnosu na zemlje članice Evropske zajednice. Od 2000.godine Republika Srbija je usvojila čitav niz strateških i zakonskih dokumenata kojima se reguliše rad energetskog sektora i sprovodi energetska politika. U martu 2013.godine usvojen je Zakon o efikasnom korišćenju energije kojim se uređuje oblast implementacije sistema energetskog menažmenta u sektor industrije, na lokalnom nivou (gradovi i opštine) i u oblasti zgradarstva. Pratećom podzakonskom regulativom detaljnije su definisani uslovi i način sprovođenja programa obuke energetskih menadžera, načinu imenovanja energetskih menadžera i uslovi za sticanje statusa obveznika sistema energetskog manadžmenta u industrijskom sektoru i kod javnih preduzeća. U radu će biti prikazan status u pogledu implementacije sistema energetskog menadžmenta u sektorima finalne potrošnje energije u Republici Srbiji, kao i aktivnosti koje se sprovode u kontekstu organizacije i izvođenja obuke, polaganja i licenciranja energetskih menažera i energetskih savetnika u sektoru industrije, na lokalnom nivou i u oblasti zgradarstva.Main primary energy sources in Serbia are coal, oil and natural gas, oil shale and renewable energy sources. The share of high quality primary energy sources (oil and natural gas) is less than 1% of total geological reserves, while the rest of 99% consists of different types of coal, with highest share of lignite – over 95%. Estimated total amount of technically available renewable energy sources potential in Serbia is 5,65 Mtoe, where 1,054 Mtoe of biomass and 0,909 Mtoe of hidro-power are already in use. Speaking of energy efficiency in final energy consumption sectors, Republic of Serbia holds unenviable position comparing to EU countries. Since 2000 there is series of strategic and legal documents that are adopted and they are governing the operation of energy sector as well as implementation of energy policy at state level. In March 2013 it was adopted Law on energy efficiency regulating implementation of energy management system within industrial sector, on local level (cities and municipalities) as well as in the sector of public buildings. Secondary legislative should define in more details training programs for energy managers, method of appointing energy managers in designated companies, as well as terms for obtaining status of designated company within system for energy management in industrial sector and in public companies. This paper presents the status of implementation of energy management system in final energy consumption sectors in Republic of Serbia, as well as survey of activities carried out in the context of organization and delivery of training program, examining and licensing the energy managers and energy advisors in industrial sector, on local level and in public buildings

Poboljšanje rada sistema procesnog i skladišnog grejanja u fabrici za proizvodnju margarina

In the process of margarine production it’s very important to maintain the temperature of margarine within the prescribed range. For this purpose the hot water from the heat substation within the plant is used, and then delivered to all consumers (tanks, apparatus, pipelines for the transport of fats, etc.). It was noted that during the production there are certain difficulties caused by insufficient butter temperature, which is particularly evident in the winter because of higher heat losses. With that in mind, this paper aims to show the principle of identifying and removing the identified deficiencies in the process and storage heating system

Correlation analysis between physico-chemical and aeration characteristics of fly ash

High volumes of coal fly ash are generated in thermal power plants all over the world. Fly ash characteristics primarily depend on coal type, combustion conditions and efficiency of particulate removal in thermal power plants. Therefore, all relevant fly ash characteristics must be investigated in order to design reliable pneumatic and hydraulic conveying systems for its removal from thermal power plants, transport to silos and disposal to landfills. A research study was conducted on more than 60 fly ash samples from a lignite fired thermal power plant. This research aim was to determine physical, chemical and aeration characteristics of fly ash samples in order to analyse their mutual correlation. Parameters that were correlated are mean diameter, bulk density, physical density, oxide compounds (SiO2, Al2O3, Fe2O3, Cao and MgO), and minimal fluidizing velocity. Simple linear regresion of experimental results showed that there was no strong correlation (R) between average diameter and bulk or physical density. Fly ash oxide composition showed significant correlation to mean diameter, but multiple linear regression should be done. Significant correlation ratio between minimal fluidization velocity and mean diameter, bulk and physical density could not be obtained

Bubrenje biljnog materijala pod uticajem natkritičnog ugljenik(IV)-oksida - matematičko modelovanje i optimizacija procesa natkritične ekstrakcije

The subject of this disertation is the swelling of plant material under the influence of supercritical carbon dioxide, as well as the effects of swelling on the process of supercritical fluid extraction (SFE). The results of experiments on the kinetics of the SFE processes were modeled using a mathematical model on the micro-scale and the Sovova’s model, which quantitatively express, through the parameters of the model, the changes that occur due to the swelling of plant material. The swelling of glandular trichomes of plants of the Lamiaceae family, swelling of hop in the form of ground particles of plant material and industrial granulates, and swelling of the particles of valerian root and rhizome of ginger were observed. The tests were conducted in order to examine the possibility of optimization the SFE process in respect to the consumption of supercritical fluids and energy. For the process of SFE of essential oils from glandular trichomes, a complex mathematical model which includes the cracking time distribution for glandular trichomes was developed. The new model describes the process of SFE with significantly higher accuracy than the existing mathematical models. For extraction at higher pressures the optimal pretreatment of plant material is defined with the goal to achieve significant savings of supercritical fluid. In the case of swelling of hops, the mass transport phenomena in granulates and cones exposed to supercritical fluid in various conditions were considered. The results explained phenomena that occur on industrial scale, especially undesirable hardening of the extraction cake. Process parameters (diffusion coefficients in the solid phase) are described by applying mathematical models to experimental results. In the case of swelling of valerian root and rhizome of ginger, significant savings of supercritical fluid consumption were achieved by choosing the optimal treatment. Process parameters (coefficients of mass transfer through the solid phase) are described by applying mathematical models to experimental results.Tema ove doktorske disertacije je ispitivanje bubrenja biljnog materijala pod uticajem natkritičnog ugljenik(IV)-oksida, kao i efekata koje bubrenje ima na proces natkritične ekstrakcije (NKE). Na rezultate eksperimenata u kojima je praćena kinetika procesa NKE primenjen je matematički model na nivou sekrecione strukture i model Sovove, kako bi se promene do kojih dolazi usled bubrenja biljnog materijala kvantitativno izrazile preko parametara modela. Ispitano je bubrenje glandularnih trihoma biljaka familije Lamiaceae, bubrenje hmelja u vidu mlevenih čestica biljnog materijala i industrijskih granulata, i bubrenje čestica korena odoljena i rizoma đumbira. Ispitivanja su vođena u pravcu optimizacije procesa NKE u odnosu na potrošnju natkritičnog fluida i energije. Za proces NKE etarskih ulja iz glandularnih trihoma razvijen je kompleksan matematički model koji uključuje raspodelu vremena pucanja glandularnih trihoma, koji opisuje proces NKE sa znatno većom tačnošću u odnosu na postojeće matematičke modele. Za ekstrakciju na višim pritiscima definisan je optimalan predtretman biljnog materijala kojim se postižu značajne uštede natkritičnog fluida. U slučaju bubrenja hmelja razmatrani su fenomeni prenosa mase u šišaricama i granulatima hmelja izloženim natkritičnom fluidu na različitim uslovima. Rezultati su objasnili pojave koje se dešavaju na industrijskom nivou, a pre svega nepoželjno očvršćavanje ekstrakcione pogače. Parametri procesa (koeficijenti difuzije kroz čvrstu fazu) opisani su primenom matematičkih modela na eksperimentalne rezultate. U slučaju bubrenja korena odoljena i rizoma đumbira, izborom optimalnog predtretmana ostvarene su značajne uštede natkritičnog fluida. Parametri procesa (koeficijenti prenosa mase kroz čvrstu fazu) opisani su primenom matematičkih modela na eksperimentaln rezultate

The mathematics of modelling the supercritical fluid extraction of essential oils from glandular trichomes

This article deals with mathematical tools used for solving equations of the improved mathematical model on the micro-scale for the process of supercritical fluid extraction of essential oils from glandular trichomes. Glandular trichomes are secretory structures of Lamiaceae plant family and as such represent the sites of essential oil synthesis and storage. It was previously noticed that during the extraction with carbon dioxide these secretory structures undergo cracking due to the solvent dissolving into the essential oil phase. In this study, the process of extraction is thoroughly analysed and mathematically presented on the fixed bed scale as well as on the single trichome scale. The finite differences method was applied for solving differential equations of the model. This included dividing the extractor vessel into twenty spatial, and extraction time into ten thousand time increments. Cracking time distribution of glandular trichomes in the form of Gamma distribution was incorporated in each of the twenty spatial increments. The model was applied to simulate experimental results of supercritical extraction from several species of the Lamiaceae family. The deviation of the model results from the experimental data was 9.6-35.7% lower for the improved model than for the model without the cracking time distribution function

Fixed bed property changes during scCO(2) extraction of natural materials - Experiments and modeling

Properties of the fixed bed of plant material during the extraction with scCO(2) from rapeseed were investigated for the two types of mechanical pretreatments: flaking and impact milling. Obtained results indicated that particle density, bulk density of the bed and consequently the bed porosity changed during the extraction. In the case of flaked rapeseed, the change of particle diameter was also detected and quantified. On the basis of experimental data linear relationships between the particle density/bed porosity/mean particle diameter and oil content in solid were established. Mathematical model based on the mass balances for the supercritical and solid phase which took into account particle density, bed porosity and particle diameter (for flaked plant material) as variables was derived. The proposed model described experimental data with high accuracy. Possible error due to neglecting the change of the fixed bed properties was presented as well

Mathematical modelling of essential oil SFE on the micro-scale - Classification of plant material

This article reports the achievements of the micro-scale (secretory-structure-scale) mathematical modelling of essential oil isolation by supercritical carbon dioxide. Some new experimental and modelling results are presented. The improved model for the supercritical fluid extraction from the glandular trichomes (peltate glands) is introduced. According to the behavior of plant secretory structures during the extraction as well as according to the modelling results, plant material was classified according to the dominant resistance to mass transfer during the extraction process. External mass transfer was the rate limiting step in the extraction from plants with secretory ducts and secretory cavities of citrus family. In the case of extraction from secretory cells, internal diffusion was the rate limiting step. In the extraction from glandular trichomes, external mass transfer, as well as diffusion through the gland membrane influenced the process

Supercritical carbon dioxide extraction of essential oils from plants with secretory ducts: Mathematical modelling on the micro-scale

In this study, the supercritical carbon dioxide extraction of essential oils from plants which contain secretory ducts as essential oil reservoirs was investigated and modelled. Supercritical carbon dioxide extraction of essential oils from Asteraceae family species, marigold and chamomile, indicated that particle size had no significant influence on the extraction rate in two outermost cases: fine milled plant material and plant material cut to particle length of 5 mm. This confirmed previously reported phenomenon that in some cases particle size had no influence on the rate of supercritical extraction process. In order to explain this behavior, the mathematical model which took into consideration the phenomena occurring on the secretory duct scale, was developed and applied to simulate experimental data of marigold and chamomile supercritical carbon dioxide extraction. Proposed model was also applied to the literature experimental data of fennel fruit supercritical fluid extraction where the same phenomenon had been observed. To obtain information regarding secretory structure, scanning electron microscopy investigation of the plant material was performed. Very good agreement of the model results and experimental data in the case of different plant species, extraction conditions and particle sizes, confirmed the basic hypothesis of the model

Optimization of Cannabis sativa supercritical CO2 extraction using Design of experiments approach

The high potential of industrial hemp (Cannabis sativa), mainly due to the high-quality fibers and bioactive compounds, coupled with the decriminalization and/or legalization in some regions of the world, led to the steady growth of scientific research over the past couple of decades [1, 2]. From an industrial point of view, cannabinoids, primarily non-psychotropic cannabidiol (CBD), are considered the most valuable compounds, as they possess a broad range of therapeutic properties, such as anxiolytic, neuroprotective, antibiotic, antiinflammatory activity, and anti-oxidant. The hemp industry has already adopted supercritical carbon dioxide scCO2 extraction as a well-established process since it is a promising ‘green’ alternative to conventional extraction methods, selective, with short processing time, and low impact on the environment. In the present study, the preliminary analysis was performed to determine the influence of different scCO2 densities based on the different combinations of process pressure and temperature on the kinetics of supercritical extraction of Cannabis sativa, extract yield and the chemical composition of obtained extracts. Experiments were performed at temperatures ranging from 40 to 60 °C and pressures ranging from 10 to 30 MPa. Prior to extraction, the plant material was grounded and submitted to decarboxylation process at 120 °C for 1 h, in order to transform cannabidiolic acid, which is the precursor present in the plant material, to CBD. Experimental design for optimization plays an important role both in science and industry, because it allows evaluation of the effects of multiple factors and their interactions on one or more response variables. The present work was focused on the further optimization of scCO2 extraction with the aim to maximize the yield of extracts with high recoveries of CBD, by means of response surface methodology (RSM), based on a central composite design (CCD) using Design of Experiment software (Stat-Ease, Design Expert). For this purpose, independent variables were temperature (40-60 °C), pressure (10-30 MPa), and scCO2 consumption (20-60 gCO2/gplant). The results showed that supercritical CO2 extraction enabled the achievement of up to 5% of total extract yield and 266–435 mg/g of CBD depending on the conditions. The high pressure and temperature, 30 MPa 60 °C, respectively, conditions that correspond to the highest density of the scCO2, generated the highest extract yield. On the contrary, lower pressure, corresponding to the lower density of CO2 was favourable for achieving a high CBD content. In addition, a higher scCO2 consumption, which is related to longer processing time, was the most dominant factor affecting the extraction process exerting a significant effect, on both examined responses, yield and CBD content. A linear model equation was proposed to express both the yield and the CBD content as a function of independent variables