ALBERT

Description: Fluid flow patterns and associated concentration fields in Y-mixers are investigated using lattice Boltzmann method (LBM) -based models. The focus lies on the impact of mixing angle on flow and concentration fields, which is varied between acute (θ = 10°) and obtuse (θ = 130°) angles. Residence time distributions are determined to study the effect of the angles on mixing and velocity patterns, in particular, different flow regimes, namely, stratified laminar, vortex and engulfment. The results from the simulations are validated with literature data and found to be in good agreement. Maximum mixing occurs in the 100 o -obtuse angle Y-mixer, attributed to the extensive engulfment of flows in the mixing channel.

Description: Pretreatment of lignocellulosic biomass is essential for overcoming its inherent recalcitrance prior to enzymatic hydrolysis and fermentation of its carbohydrate components into biofuels and bioproducts. Among the myriad of existing pretreatment methods, the hot water pretreatment with no-chemical usage is a particularly attractive approach due to its fewer safety and environmental concerns, as well as relative low cost. The hydronium ions dissociated from water at elevated temperatures can catalyze the deconstruction of lignocellulosic biomass into fermentable sugars, digestible cellulose, and lignin fragments. However, a prohibitive amount of sugar degradation products particularly generating in conventional batch systems limit the efficiency of hot water pretreatment. Although the advanced continuous reaction systems like flowthrough systems are prone to reduce the sugar degradation compounds thereby enhancing the sugar recovery, excessive water consumption accompanied with the over dilute sugar streams still impede the implementation of hot water pretreatment to be an economical viable pathway. These limitations of hot water pretreatment are considered to be associated with the scant attention of water-biomass interaction mechanism, as well as the engineering aspects regarding kinetic modeling and reactor configurations. Thus, extrapolating this information from scattered literatures would play a vital role to complete the comprehensive understanding of the hot water pretreatment. This review aims to fill in the blank of those critical factors influencing hot water pretreatment of lignocellulosic biomass, in terms of chemistry and engineering fundamentals to understand the correct axiomatic approaches needed to advance this technology. In particular, various reactor configurations and kinetic models are evaluated herein to explore the optimization strategies of hot water pretreatment toward application.

Description: During the past years cost pressure on the European chemical companies grew dramatically by increased competition from low-labor-cost BRIC countries on the one side and the U.S., favored by decreased energy costs due to shale gas exploitation, on the other side. Raising costs for energy consumption and wages come on top. Lonza, as a mid-sized chemical company located in a high-income-country, faced the need of cost reduction long time before and established highly efficient procedures in both, development and production, with the aim to decrease costs and already successfully applied since years. The paper describes some of the applied techniques in detail and shows their potential in terms of time and cost reduction. Furthermore, Lonza works with great emphasis on future solutions.

Description: Solid-liquid extraction using a laboratory robot, where anthocyanins are leached from dried red vine leaves ( vitis vinifera ), is evaluated with respect to precision and accuracy. The solid handling of the robot results in standard deviations between ± 0.6 and ± 1.8 depending on the particle size (max. 630 µm). For liquid handling standard deviations are from ± 0.8 to ± 2.6 depending on the volatility of the solvents. The validated, fully automated natural plant extraction-robot shows yields based on dry matter from 1.3 % to 0.8 %, 1.15 % to 0.55 % and 0.4 to 0.15 % for methanol, water (HCl, pH = 2.5) and ethanol and is improving with increasing particle size. Manually performed extraction kinetics experiments are compared with the robot and indicate a variance of 0.1 %. With respect to process intensification, a comparison of yields obtained by microwave and ultrasonic supported extraction in comparison to laboratory robot shaking and stirred single-stage batch experiments was performed.

Description: Aerial view of pipes of the thermal power plant. © Nickolay Vinokurov/Shutterstock

Description: The electrochemical reduction of CO 2 is a promising method for its conversion which still suffers from important challenges that have to be solved before industrial realization becomes attractive. This study describes the optimization of gas diffusion electrodes with respect to catalyst dispersion and mass transport limitations allowing solubility issues to be circumvented and current densities to be increased to industrially relevant values. Consequently, the transfer of the promising results from semi-batch experiments into continuous mode of operation is demonstrated, and it is shown how the energetic efficiency can be significantly improved by the choice of electrolyte, in terms of concentration and type. Thereby ohmic losses can be decreased and the intrinsic activity improved.

Description: In a future energy system, flexible reactor operation may be needed if renewable electricity is converted to chemical energy carriers (synfuels). Limiting factors for the flexibility in a synfuel process can occur on different scales (catalyst, reactor, process). The present study addresses transient catalyst and reactor effects in 3-phase catalytic synthesis reactors with low-temperature Fischer-Tropsch synthesis as example reaction. A method was developed based on lab-scale experiments with step-changes and periodic-changes of inlet variables and mathematical models for experimental design and data analysis. Changes of feed gas flow, syngas H 2 /CO-ratio and temperature as inlet variables led, in some cases, to transient effects caused by catalyst changes or by reactor characteristics (e.g. residence times of gas components affected by their solubility in liquid hydrocarbon products). Catalyst changes include the reversible storage of carbon species during CO-rich intervals and hydrogenation of these carbon species during H 2 -rich intervals. The approach will help to scale-up for industrial applications and can be applied to other synthesis reactions.

Description: Profile measurements in a catalytic gauze reactor are conducted for catalytically assisted methane combustion over platinum. The reactor combines a capillary sampling technique with a novel fiber-optic Laser-Induced Fluorescence (LIF) Spectroscopy method for detection and quantification of gas phase OH[[[Wingdings;F09E]]] radicals serving as indicator species for gas phase reactions. The steep spatial gradients in the vicinity of the gauze are resolved at submillimeter scale. Experimental profiles are compared with three dimensional numerical reactor simulations including flow, mass transport, heat transport and microkinetic models for both surface and gas phase chemistry. The results provide insight into the interaction of chemistry and transport upstream, at and downstream the catalytic gauze and the interaction of surface and gas phase reactions by exchange of heat and radicals released from the catalyst surface.

Description: A packed bed algae biofilm reactor was developed using porous and non-porous dual packings. The biofilm was cultivated on reticulated polyurethane foam cubes of 0.01 m dimension. The non-porous glass raschigs were used as bed support that helps the removal of generated gas from the system. The effect of variables such as column L/D ratio, catalyst cube dimension and feed flow rate on the treatment of sewage water was studied. The reaction kinetics indicates that the nutrients uptake rate is dependent on both pore and film diffusion. The kinetics of uptake of nutrients follows a pseudo-first order reaction. From the pseudo reaction rate constant, Thiele Modulus and effectiveness factor were calculated and a kinetic model equation for fractional nutrients uptake was developed in terms of operating variables. It was observed that the model can predict the reaction rate with ±5% deviation. The packed bed column was operated continuously for 90 days with 76-83% of TN and 70-76% TP removal in 24 h of residence time and the results obtained may be useful for large-scale treatment of sewage water.

Description: With the high interest in renewable resources, the field of biosorption has undergone a huge leap in importance in recent years. The arsenic contamination in water causes many diseases. Various biosorbent materials have been tested for their ability to remove the two inorganic arsenic species commonly found in water; arsenite As (III) and arsenate As (V). The review evaluates source and various biosorbent used for arsenic removal from wastewater. The arsenic biosorption is influenced by the pH of aqueous phase, the concentration of arsenic, the presence of competing ions and arsenic speciation. The biosorption kinetic of As (III) and As (V) by biosorbents has been reported to be rapid, with greater than 80 % biosorption occurring between 30- 60 min, followed by second step which may take up several hours. The pseudo-second order model showed the best fit for kinetics of arsenic, which corresponds to a chemisorption process. Langmuir equation is widely used in a large number of equilibrium studies; this finding indicates that most arsenic ions are adsorbed in monolayer form and removal is better for As (III) than for As (V).

Description: Ionotropic alginate microgels are commonly used for bioencapsulation applications and the air extrusion system is one of the common methods employed to produce these microgels. Although there have been many individual studies, no single report to date has comprehensively summarized the findings and results of the use of this system. Our review gives insight into the air extrusion methods, covering the setup, type and characteristics of the system, focussing on their innovative aspects. Characterization techniques for the resulting microgels are presented, along with the influence of process variables on their product size, and the development of empirical models for size prediction.

Description: For the purpose of a long-term heat storage system based on water sorption, a composite material consisting of 15 wt.% CaCl 2 and zeolite Ca-X (prepared by ion-exchange with Ca 2+ and subsequent impregnation with CaCl 2 of a binder-free granulated zeolite Na-X) was prepared on a technical scale. In a lab-scale apparatus, the heat storage density of the composite material reaches values up to 260 kWh m -3 for water vapor partial pressures up to 33 mbar. As compared to the pure zeolites Ca-X and Na-X, this corresponds to an increase in heat storage density of 45 % and 68 %, respectively. An engineering concept based on the mechanical transport of the composite heat storage material through a pre- and a main reactor was demonstrated in a “hardware in the loop” test bench.

Description: A model of the steam gasification of a single char particle driven by high intensity radiation was developed and experimentally verified with available measurements in literature. This was used to explore the sensitivity of particle surface temperature and heat transfer mechanisms to variations in particle diameters (100m to 1900m), radiative heat flux (1MW/m 2 to 4MW/m 2 ) and the concentration of the gasification agent, H 2 O (0.2 to 0.8 mole fraction) under typical conditions for solar gasification reactors. The results highlight the importance of particle diameter in influencing solar to chemical energy conversion efficiency and assist in the selection of appropriate feedstock particles to match the conditions in specific solar gasification reactors.

Description: Distillation of hydrocarbons was investigated to decrease energy consumption by applying the columns with the coupled heat and material flows. The elements of downstream processes were considered such as separation of the catalytic cracking gas and the recovery of benzene from petroleum and coking coal products by extractive distillation with N-methylpyrrolidone. It was found that the thermally coupled columns applied for the separation reduced energy consumption for the catalytic cracking gas separation up to 13.1% and for the benzene recovering up to 28.7%.

Description: Rapid granulation of biomass and reactor start-up has been studied in a novel denitrifying reactor. The effect of wastewater characteristics, reactor operating conditions and reactor geometry on microbial granulation has been studied. It was possible to achieve granulation in just 15 days of reactor start-up. In 15 days the settling velocity of the granules was 1.5 cm s -1 , which is almost 10 folds higher than that of seed sludge. The reactor was able to handle a nitrate loading rate of 50 g NO 3 -N m -3 day -1 in 3 days of reactor start-up with rates reaching up to 460 g NO 3 -N m -3 day -1 in just 30 days of reactor start-up with a removal efficiency of almost 100%. Based on the experimental observation, a hypothesis for the cause of rapid granulation has been proposed.

Description: K-solubilizing bacteria were isolated from solar salt pans of CSIR-CSMCRI’s experimental salt farm and Sambhar lake, mining areas of Naseerabad and wastewater from marble cutting machinery. Seven promising bacterial isolates from Makrana, three from Sambhar lake and three from Naseerabad were found to have comparatively better potassium solubilizing capacity. Out of these, three potential bacterial isolates were identified as Acinetobacter soli (MTCC 5918), Enterobacter xiangfangensis (MTCC 5917) and Acinetobacter baumannii (MTCC 5916). Thereafter, Acinetobacter soli was found to have maximum potassium releasing capacity of 80 mg/l in supernatant, which may be further applied as a biofertilizer.

Description: The development of floating liquefied natural gas (FLNG) plants has resulted in a focus on reducing the weight and size of the topside processing facilities for these units. The conventional fractionation of natural gas liquids (NGL) in LNG plants implies a direct sequence of three or more conventional distillation columns requiring different levels of refrigeration. The results of a feasibility study are described, indicating that a packed three-product dividing-wall column (DWC) could replace conventional de-ethanizer and depropanizer columns. This could provide significant energy, hardware, weight, and footprint benefits, but, very likely, at the expense of an unaffordable cold utilities demand. 1) A conventional demethanizer combined with a three-product dividing-wall column operated at moderate pressure appears to be a promising alternative for the conventional three-column sequence as encountered in natural gas liquids fractionation plants. In addition to the overall energy saving, such a configuration enables also weight, hardware, and footprint reduction.

Description: A 3D numerical model was developed for studying the multiphase flow and heat transfer process in a radiant syngas cooler (RSC). Realizable k-ϵ turbulent and discrete random walk models were adopted to simulate gas phase and particle phase flow fields, respectively. The surface temperature of the membrane wall was calculated by heat flux balance equations. The calculated temperature distribution was validated by comparing calculated values with measured data of an industrial RSC. Four different membrane wall arrangements of RSC, namely, ordinary membrane wall (OMW), partial division wall (PDW), annular division wall (ADW), and fin division wall (FDW), were designed for a specific condition. The radiant syngas cooler is one of the critical and expensive components of power plants. A three-dimensional numerical model was developed to predict the complex multiphase flow and heat transfer process in such a cooler of entrained-flow coal gasification for optimization. Four different membrane wall arrangements were designed and evaluated for a specific condition.

Description: In order to improve the flow uniformity in plate-fin heat exchanger (PFHE), a modified header structure with a plain baffle inside is proposed in this study. Flow distribution and pressure drop in header were studied by using numerical method. Results show that the modified header is high-efficient in improving the flow uniformity in header of PFHE with negligible pressure drop increase. Then, a performance effectiveness factor was introduced to predict the effects of the modified structure on the performance of PFHE. Finally, influences of baffle structure parameters on modified structure performances were further discussed. Conclusions of this paper indicate that the modified header structure can effectively improve the performance of PFHE.

Description: Continuous manufacturing of fine chemical, life science, and pharmaceutical products is under recent investigation in R&D. As cooling crystallization is an important unit operation for purification of products, continuously operated, scalable devices are required for process development on lab-scale. A tubular crystallizer was developed, based on the coiled flow inverter (CFI) design. Experimental characterization proved a narrow residence time distribution (RTD) of the liquid phase close to ideal plug flow. Counter-current air cooling allows for adjusting linear and curved temperature profiles. Unseeded operation with the l-alanine (water) system demonstrated that nucleation has to be actively controlled to successfully apply intensified continuous cooling crystallization processes.

Description: The stability of a polymorph and the rate of polymorphic transformation are usually affected by solvent, and thus a molecular level understanding of the solvent effect on the nucleation of stable form during the polymorphic transfomration process is necessary to effectively control the whole process. In this work, the role of water in the nucleation of the stable β form of L-glutamic acid (L-Glu) on three typical surfaces of the metastable α form is investigated via molecular dynamics simulation. By comparing the simulation results on the surfaces in contact with solution with those on the surfaces in vacuum, it is revealed that water molecules have not made any change in the order of the adsorption energies for the solute molecules on the three surfaces, but reduced the absolute values of the adsorption energies with the extent increasing in the order of {011} 〈 {111} 〈 {001}, and retarded the clustering behavior of solute molecules with the same order. In addition, water molecules also weaken the inductive effects of the surfaces on the conformational change of α to β. In general, the effect of water on the nucleation of the β form on the surfaces of α form unraveled here will aid the understanding of polymorphic transformation of L-Glu in solution.

Description: In view of a kind of stripping column used widely in chemical industry, being in operation of total cold reflux and without top light product, a new stripping process is suggested in this paper. It takes dual feeds of the hot plus the cold by replacing partial cold reflux with a part of cold feed, resulting in significant reduction of energy consumption and simplification of the overhead vapor route. Due to no any change on the column’s body and only a pipe needed, this new process can be promoted conveniently in retrofitted projects. Further an optimization study is developed for choosing proper flow rate of cold feed and column’s running pressure. An application in a stripper of pre-hydrotreating resultant of oil catalytic reformer shows that the new process is valid.

Description: In the present study, efforts have been made for replacing sodium bicarbonate with ammonium bicarbonate (recovered from effluent of the pigment industry) for cultivation of CSMCRI’s Chlorella variabilis (ATCC PTA 12198) with enhanced biomass and lipid productivity. Utilizing ammonium bicarbonate in the medium (instead of sodium bicarbonate) yielded better biomass and productivity having less production age of 9 days as compared to Zarrouk’s medium in 5 L flask. Also, the modified medium containing ammonium bicarbonate yielded comparatively better total reducing sugar content which may be used for bioethanol production or may serve as the carbon source for further mixotrophic growth of Chlorella variabilis (PTA 12198).

Description: Bioremediation of environments, polluted with hydrocarbons, is among the most important and challenging technological and environmental issues. The use of plants and microbes is one of the most efficient methods for bioremediation. A new combination of grasses, Kentucky bluegrass ( Poa pratensis ) and Bermuda grass ( Cynodon dactylon ), and bacteria, Rhodococcus erythropolis , was hypothesized for the bioremediation of naturally polluted soils with hydrocarbons around Isfahan refinery, Iran. A 90-day greenhouse experiment, as a factorial design with 12 treatments including soil inoculation with bacteria as well as soil sterilization using both plants in three replicates were examined. Both grasses significantly decreased the concentration of soil hydrocarbons compared with the control polluted soil, although Kentucky grass was the more effective one. The bacteria enhanced the bioremediation abilities of both plants, especially Kentucky grass. Soil sterilization significantly decreased the rate of hydrocarbons in the soil. The positive effects of bacteria on the process of bioaugmentation, specifically, due to their adaptability potential with the grasses examined in this research work, make this method of bioremediation strongly recommendable. However, more research is essential to illuminate the new details on the role of R. erythropolis in polluted soils with hydrocarbons.

Description: In this work, the design and optimization of different methods for propylene/propane separation in downstream of Methanol-to-Olefin (MTO) process is illustrated. Propylene and propane have similar boiling point, which requires large number of trays and energy when separating by a traditional single column with industrial low pressure steam as reboiler heat source (TRA-LPS case). Some alternatives are studied in this work, including the traditional column using waste hot water as heat resource (TRA-HW), the implement of a vapor recompression cycle (VRC) configuration, and the use of extractive distillation (ED) with acetonitrile solution as entrainer. Comparing with the case of TRA-LPS, the total annual cost can be reduced by 46.9%, 4.6%, and 47.8% for cases of TRA-HW, VRC, and ED, respectively. The required number of trays for separation is reduced by 25.6%, 10.3%, and 42.5% for three cases in the order mentioned above. It can be concluded that TRA-HW and ED cases can be two promising alternatives for this separation.

Description: A microreactor system was developed to investigate the cyclization of pseudoionone (PI) catalyzed by sulfuric acid. The conversion of PI and selectivities of α -ionone and β -ionone were explored under various conditions. The effects of residence time, molar ratio of acid/PI (M-ratio), reaction temperature and sulfuric acid concentration on the reaction were investigated. It was found that sulfuric acid concentration played a vital role in the reaction system, which could greatly influence the conversion and selectivities. 77% β -ionone yield and up to 93% total yield of α -ionone and β -ionone were achieved under optimized conditions. In addition, the formation of byproducts was investigated in detail and the side reactions could be restrained by optimizing the reaction parameters.

Description: The micro-particle image velocimetry (micro-PIV) is a quantitative full field technique for the velocity measurement for flows in microfluidics. The flow fields of both Newtonian and non-Newtonian fluids in microchannels were investigated by micro-PIV. The velocity profiles in various PMMA square microchannels were measured. Different concentrations of various polyacrylamide (PAAm) aqueous solutions were used as non-Newtonian fluids. Two viscous Newtonian fluids were also employed to serve as reference, in particular to validate a lattice Boltzmann (LB) simulation. The results show that satisfactory flow measurements could be realized by the micro-PIV technique. The experimental velocity profile compares favourably with the LB simulation and an approximate solution. The experimentally measured velocity profile can lead to the quantification of the flow index of non-Newtonian fluids as an in-line rheological characterisation.

Description: The spontaneous polymerization, i.e, runaway, of acrylic acid during storage is a serious problem which may endanger life and facilities. In respond to a starting polymerization, effective emergency measures are necessary. For these investigations, a polytropic reactor setup, namely, an isoperibolic reactor is introduced to offer a rational access to restabilization studies. Furthermore, safety diagrams are created where the used amount of stabilizer is plotted against the polymerization progress in terms of the rising temperature. Such diagrams display the minimum required amount of the shortstopper (RESTAB™) for terminating a runaway polymerization. The suitability of the reaction setup is investigated using unstabilized acrylic acid. The restabilization of monomers in tanks is necessary to prevent a spontaneous polymerization, a so-called runaway, which in case of acrylic acid cannot only lead to a shut-down and damage of chemical plants, but also cause casualties. The necessary amount to terminate the undesired starting polymerization immediately is investigated in especially developed isoperibolic reactors.

Description: Saturated branched fatty derivatives are of great interest for the lubricants and cosmetics industry due to their improved temperature and viscosity behavior compared to the corresponding linear homologues. One way to produce saturated branched derivatives is the homogeneously rhodium catalyzed conjugation and co-oligomerization of linoleic compounds based on renewable resources (e.g. sunflower oil) with ethene. The paper studies the catalyst extraction behavior of the homogeneous rhodium catalyst RhCl 3 *3H 2 O from saturated branched fatty derivatives for catalyst recycling. Investigation of the extraction parameters was performed using the model substance isostearic acid. Additionally extraction of rhodium from co-oligomer mixtures with different grade of saturation was carried out successfully. Also the influence of solvent residues from prior reaction steps has been investigated.

Description: 2,4,5-Trifluorobromobenzene is a valuable intermediate with important application in the synthesis of biologically active peptides and fluorescent reagents. In this paper, a continuous-flow system has been successfully developed for the synthesis of 2,4,5-trifluorobromobenzene in microreactor using FeBr 3 as a catalyst, which is steadily generated in situ from the reaction of Br 2 and Fe. The procedure is efficient and easy-to-handle, and 2,4,5-trifluorobromobenzene can be obtained in minutes in high yields.

Description: Fuzzy-based approaches like fuzzy chance constrained programming (FCCP) and fuzzy expected value model (FEVM) have been applied to a multi-objective optimization problem of the industrial grinding process to carry out the uncertainty analysis. Results are compared with respect to the power of risk averseness adopted in the approaches used. The extent of constraint satisfaction due to the presence of uncertain parameters can be accommodated assuming credibility of constraint satisfaction under the FCCP framework whereas the robust set of parameters in the FEVM approach is determined by considering the expectation terms for objectives and constraints. Nonlinear relation of uncertain parameters has been handled by adopting simulation-based approaches while computing the credibility. These approaches are very generic and can be applied for the study of parametric sensitivity for any process model in a novel manner. Multi-objective optimization of an industrial grinding process under uncertainties in various process parameters was performed. The uncertain optimization problem was converted into an equivalent deterministic optimization problem by credibility-based fuzzy chance constrained programming. The proposed approaches can be applied to study parametric sensitivity for any process model.

Description: There are many approaches to face the issue of agent encapsulation as method to protect sensitive substances against outer influences. The possibility of the use of inclusion containing crystals as encapsulation material was investigated. Since many products are water-based media the low water soluble substance salicylic acid (SA) was chosen to investigate its qualities as a container substance. Therefore, the solubility of SA was investigated in dependence on the composition of the antisolvent water and the solvent ethanol by means of a ternary phase diagram. Moreover, SA container crystals were generated and filled by means of an antisolvent crystallization method. Copper sulfate and ascorbic acid could successfully be encapsulated in two case studies.

Description: The phase equilibria of supercritical CO 2 + alkane + alcohol mixtures were studied using online gas chromatography. Gas chromatograph design criteria and quantitative detector calibration methods are presented. An adapted manual calibration injection technique eliminated liner overload and pressure wave effects. Observation of the cell contents has proven essential for accurate vapor phase sampling. Visuals, often not visible to the naked eye, show that sampling can disrupt an equilibrated high-pressure system even though pressure and temperature remain constant to within 0.1 bar and 0.01 °C. Such disruptions may manifest in one of three phenomena: global mist formation, localized mist formation, or no-warning droplet formation.

Description: Natural gas is a primary source of energy and most of the natural gas reserves are contaminated with high percentages of CO 2 . Removal of CO 2 from natural gas is necessary to purify the gas and to enhance the calorific value of gas. Different processes are used for CO 2 removal from natural gas, but all these processes have several limitations. Membrane technology is an efficient technique for CO 2 removal from natural gas due to its ease of operation and low cost. Among different types of membranes used for gas separation, polymeric membranes exhibit excellent separation performance. In polymeric membranes, the separation performance is affected by plasticization and swelling in the membrane. Recent technological advancements and major problems in polymeric membranes are reported in this review. Separation performance of polymeric membranes is highlighted in terms of permeability and selectivity. Moreover, techniques to overcome the major problems in polymeric membranes are highlighted. Among all these techniques, crosslinking and thermal treatment are commonly used to minimize the effect of plasticization and swelling in the membrane. For future perspectives, it can be concluded that there is a need to find more efficient methods to overcome the problems of plasticization and swelling in the polymeric membrane.

Description: Selective acetylene hydrogenation over a commercial Pd-Ag/Al 2 O 3 catalyst was carried out under industrial operation conditions that correspond to the “tail-end” process. Pyrolysis gas chromatography-mass spectrometry was used to analyze the composition of the green oil. C8–C30 linear hydrocarbons with even carbon-numbered chains were detected as the main components of the green oil. Its chain length increased with operating time, temperature, and hydrogen partial pressure, and decreased with acetylene partial pressure. The composition of the green oil deviates from the Anderson-Schulz-Flory distribution. Both coupling-hydrogenation and hydrogenation-coupling mechanisms are involved in green oil formation. The composition evolution of green oil which is formed during acetylene selective hydrogenation over a commercial Pd-Ag catalyst is investigated by pyrolysis gas chromatography-mass spectrometry and other methods and reaction routes are proposed. The results are valuable to avoid green oil formation in industrial processes and for the development of new catalysts.

Description: In this work, the steady state design and optimization for a methanol-to-olefin (MTO) process is studied. MTO process is a novel route for light olefin production, especially ethylene and propylene. Comparing with the traditional way to produce olefins by steam cracking, MTO process offers benefits such as more flexible range of ethylene to propylene ratio, higher selectivity toward light olefin, and mild reaction conditions. The design of overall MTO process is divided into four sections, which are reaction section, conditioning section, first separation section, and second separation section. After the design of each sub-part, optimization works are performed, in which the design and operating variables are thoroughly investigated. Through rigorous simulation, a more economically competitive design flowsheet of the overall MTO process is proposed.

Description: Harvesting is one of the most important operations in microalgal biomass utilization. Two types of flocculants are widely used in flocculation. Inorganic flocculants are usually cheaper than organic flocculants, but leave more contaminants on the culture media. The combination of one inorganic and one organic flocculant and its synergy for the marine microalgae Chaetoceros gracilis harvesting process is reported. The efficiency of eight inorganic and five organic flocculants was studied. The results show that, when only FeCl 3 was used, high doses were required for high levels of biomass recovery, whereas chitosan alone led to poor recoveries. However, when both flocculants were used in combined flocculation, total biomass recovery was achieved, even at low doses. Microalgae cultivated in photobioreactors are considered a promising source of energy. To separate the algal biomass, flocculation is often applied. Here, the combined use of one inorganic and one organic flocculant is studied for the harvesting of the microalgae Chaetoceros gracilis . It could be shown that the combined use results in better biomass recovery than each alone.

Description: The catalyst-overloading strategy is often adopted to extend the catalytic lifetime of fixed catalyst bed reactors in chemical processes. Confirmation of the adoptability of this strategy to Mo/HZSM-5 catalyst effective for the non-oxidative methane dehydroaromatization was made for the first time in this work by examining the effect of bed height on the catalytic stability and lifetime aromatic productivity of an integral fixed Mo/HZSM-5 bed at 1073 K and different CH 4 superficial velocities. Increasing bed height has been shown to have a very limited effect on extending either the stable period of aromatics production of the bed or its lifetime aromatic productivity. Simultaneous coke formation over all layers of the bed has also been confirmed to be responsible for rapid deactivation of the whole bed and pyrolysis of the intermediate C 2 H 4 has been concluded to be the dominant route to coke formation.

Description: A simplified transient model for fixed bed reactors was extended to account for the heat sink effect of the phase change material diluent in the Fischer-Tropsch reactor energy balance. The resulting model was found to accurately approximate the more rigorous 2-dimensional model with significantly less computational requirements even at the hotspot, where the reactor enthalpy balance is most sensitive. As anticipated, the presence of the encapsulated phase change material in the reactor induced thermal inertia, thereby restricting the temperature ramp rate in the reactor to acceptably safe operational limits for the catalyst. Although there was a reduction in both the CH 4 and C 5+ productivity, the reduction in CH 4 production was up to four times that of the C 5+ at the same coolant temperature.

Description: Spray towers allow for controlling air pollution in which a liquid is sprayed in small droplets to produce a large interfacial area for mass transfer between a gas and a liquid phase. An experimental study of a spray tower for removing SO 2 is described. The experiments were carried out under different operating conditions by varying the gas velocity, liquid flow rate, and SO 2 concentration. SO 2 removal efficiency, volumetric mass transfer coefficient, and liquid-film formation as a result of the collision of droplets against the tower wall are investigated. Removal efficiency and volumetric mass transfer coefficient are analyzed as a function of gas velocity, liquid flow rate, and SO 2 concentration, while liquid-film formation is evaluated as a function of tower height. The results indicate high removal efficiency. Correlations to predict the volumetric mass transfer coefficient are also proposed. Spray towers enable the control of air pollution. The SO 2 removal efficiency of such a tower was investigated under various operating conditions in terms of liquid flow rate, gas flow rate, and inlet SO 2 concentration. The formation of a liquid film and its impact on the droplet flow rate down the tower was analyzed and correlations to predict the volumetric mass transfer coefficient are proposed.

Description: Potassium-modified FeCrAl alloy wire mesh was developed as a catalytic diesel particulate filter (CDPF) to suppress the emission of soot from diesel engine. K species were deposited on wire mesh via a chemical vapor deposition method, in which a model soot was used to convert KOH into metallic K at high temperatures (≥ 800 °C) to subsequently activate the wire mesh. The XRF and SEM tests showed that the metallic K reacted with the enriched Al 2 O 3 component on the surface that was derived from the segregation and successive oxidation during the pre-calcination at 950 °C. The resulted layer of K-O-Al species was proved to offer a remarkable activity and stability for catalytic oxidation of diesel soot. The cyclic activity evaluation demonstrated that the K-activated wire mesh can lower the initial temperature of soot combustion to ca. 350 °C and keep the activity for five cycles. The adverse impact of water on the activities suggests that the anti-poising ability of the monolithic catalyst against water needs to be improved for the application in practice.

Description: A draft-tube spouted bed reactor (DTSB) was equipped with an auxiliary aeration device to provide air into the annular region and so improve the oxygen transfer efficiency. The effects of total air-flow rate and its distribution between spout and annulus, liquid phase viscosity (water and carboxymethylcellulose solutions), and solid holdup (glass and cyclodextrin polymer beads) on oxygen transfer efficiency were discussed. Oxygen transfer coefficient increased with air flow rate and the ratio of air flowing through annulus, whereas it decreased with viscosity and solid holdup. A correlation was proposed to predict the transfer coefficient in DTSB reactors with primary and auxiliary aeration. A good fitting was achieved between the experimental data and those estimated with the model.

Description: Hydrogenation of liquid organic hydrogen carriers (LOHC) is usually carried out in liquid phase. To measure the kinetic of this hydrogenation an experimental setup using insitu Raman-spectroscopy for analysis of the reaction mixture is proposed. With this setup it is possible to perform hydrogenation reaction at temperatures of up to 573 K and pressures up to 25 MPa. For validation of the experimental setup the hydrogenation of 1octene was measured in liquid phase. It is shown that the reaction progress can be monitored in detail by Ramanspectroscopy. To determine kinetic parameters from the experimental data two modeling approaches were used: a classic kinetic model (CKM) and a thermodynamic kinetic model (TKM). These results were compared to literature data.

Description: Thermal-expansionary pretreatment is a novel environmentally friendly technology that has a very high potential to be installed in various industrial biofuel technologies, where lignocellulosic biomass is processed. Its principle is based on the boiling of biomass in water that is maintained by pressure in liquid state, under a process temperature and a residence time with subsequent rapid batch decompression. The performance of the intensified pretreatment technology is shown in intensified full-scale biogas plant, which is raised from laboratory equipment. The wheat straw is a model processing substrate. In order to show the difference, the results compared with the regular non-intensified biogas plant. So, both types have the same input amount of the substrate. It is found that, the intensified plant has 50% higher power than the non-intensified. The economic analysis and payback period was performed for both types of the plant.

Description: An adaptive pseudospectral method with two novel strategies is proposed to solve the constrained dynamic optimization problems in chemical engineering. The first strategy is to introduce slope information in designing appropriate subintervals, so that the approach becomes more efficient to track the optimal control profiles. The second strategy is to redistribute the collocation points based on the approximation error. This strategy ensures the accuracy of the method. Two constrained dynamic optimization problems with multiple control variables are tested as illustrations, and the proposed approach is compared with other methods. The research results reveal the effectiveness of the proposed method in improving the solution accuracy of the dynamic optimization problems.

Description: This paper discusses the conversion of mineral magnesite to magnesium oxide, methane, carbon dioxide, and carbon monoxide in hydrogen atmosphere between 748 K and 778 K at ambient to 1.2 MPa overpressure without catalysts. Low temperature and elevated pressure facilitate methane formation, whereas moderate to high temperature and low pressure facilitate carbon monoxide formation. Methane is formed directly without any additional catalyst. Carbon dioxide emissions are decreased substantially in reductive calcination. Additional experiments revealed that reductively calcined magnesium oxide is a highly active reverse water gas shift catalyst. Carbon monoxide formation from gaseous carbon dioxide and hydrogen at catalytically active magnesium oxide has been reproducibly confirmed. Further reduction of carbon monoxide to methane is not catalyzed by reductively calcined magnesium oxide.

Description: Nonlinear frequency response (NFR) method, which is an analytical, fast and easy method for evaluating the performance of forced periodically operated chemical reactors is used in this, two-part paper, for investigation of possible improvements of a non-isothermal continuous stirred tank reactor (CSTR) with simple reaction mechanism, when inlet concentration and flow-rate are periodically modulated, separately or simultaneously. Product yield corresponding to periodic operations is defined, expressions for its estimation, based on the NFR method, are derived for each investigated case and it is used for evaluating the performance improvements achieved through periodic operation. In Part I the general non-isothermal case is considered and in Part II, these results are applied to the case of an adiabatic CSTR and implemented for evaluation of possible improvements for the case of acetic acid anhydride hydrolysis reaction.

Description: The methanation of CO 2 was studied in a wall-cooled single-tube fixed bed reactor with a nickel based catalyst. Heat transfer and kinetic parameters were experimentally determined. Temperature profiles were recorded at different conditions: (i) inlet gas mixtures with CO 2 diluted in H 2 or N 2 , (ii) tubes with 2 or 4 cm in diameter, and (iii) pressures of 1 or 4 bar at 160 to 200 °C. Modelling of CO 2 conversion and temperature profiles by a two-dimensional reactor model was successfully achieved. The study is completed by modelling technical reactors both for upgrading of biogas and for conversion of a CO 2 /H 2 feed gas free of CH 4 ; design data of reactors for a production of 450 m 3 SNG h – 1 are given.

Description: Nonlinear frequency response (NFR) method, which is an analytical, fast and easy method for evaluating the performance of forced periodically operated chemical reactors, is used for the investigation of possible improvements of a non-isothermal continuous stirred tank reactor (CSTR). A model reaction characterized by a simple reaction mechanism is considered. Inlet concentration and flow-rate are periodically modulated, separately or simultaneously. The product yield is used for evaluating the performance improvements. In Part I of this paper the general non-isothermal case was considered. In this Part II the results are applied to the case of an adiabatic CSTR. For demonstration a laboratory-scale adiabatic CSTR is analyzed applying kinetic parameters for the hydrolysis of acetic acid anhydride. It is shown that improvement can be obtained for simultaneous modulation of the two inputs, with appropriately chosen forcing parameters (frequency, input amplitudes and phase difference).

Description: Residence time experiments are used to study the single-phase flow hydrodynamics of a rotor-stator spinning disc reactor. Two reactor setups of different sizes are examined in order to identify the effects of the reactor’s operating parameters. In order to precisely determine the central moments of the reactors transfer functions, which allow conclusions on the fluid flow profiles in the gap, a deconvolution procedure in time as well as in frequency domain is established. Different residence time models are compared with regard to their applicability for deconvolution and fitting. The spatial extensions of the convectionally backmixed and the plug flow regions are quantified by means of a threshold method. Furthermore, the obtained results are incorporated into an engineering model and compared to literature.

Description: The spinning disc reactor (SDR) as part of modern process intensification is used for the size-selective synthesis and functionalization of nanoscale superparamagnetic iron oxide particles in a single step continuous flow process. Magnetite (Fe 3 O 4 ) particles in the range from 2.9 to 9.3 nm are precipitated in a highly sheared thin liquid film on a rapidly rotating disc at speeds between 500 and 5000 min -1 . A novel liquid-liquid synthesis with increased througput is presented whereas control over particle size is reached via adjustable micromixing properties on the disc. The nanoparticles with tailored size, narrow size distribution and high saturation magnetization (〉 70 emu g -1 ) can thus meet the special requirements for the use in biotechnological, medical and catalytic applications. The functionalization of the particles with oleic acid for higher biocompatibility and better dispersibility is accomplished in the SDR in a single step.

Description: The adsorption capacity of a shale gas reservoir is mainly determined by the isothermal adsorption experiment. In this study, the building conditions and performances of seven single-component and five multi-component adsorption models were compared and analyzed. The results show that most shale gas reservoir adsorption characteristics obey those of type I on the macroscopic scale. The adsorption isotherms of single components can be described by the Langmuir-Freundlich, Langmuir, and Toth models. The revised Langmuir, extended Langmuir, and the loading ratio correlation (LRC) models can be applied to binary-component mixtures; and the extended Langmuir and LRC models perform best for shale gas. The obtained results might have an important promoting effect for modeling the shortage of shale gas. Different adsorption models were analyzed for describing the adsorption of CH 4 , N 2 , CO 2 , and their mixtures, representing shale gas. The modeling results show that the adsorption characteristics of most shale gas reservoirs obey those of type I on the macroscopic scale. Models suitable for predicting the adsorption of shale gas were identified.

Description: The hydrodynamics of bubbly flows is dominated by bubble induced turbulence and bubble-bubble interactions. Both phenomena influence the gas-liquid mass transfer as well as the mixing of reactants. If the time scales of mass transfer and mixing are in the same order as the time scales of a parallel-consecutive reaction, the yield and selectivity will be affected by the local hydrodynamics. In this study, an experimental setup is presented that enables the investigation of mass transfer during well-defined and adjustable bubble collisions. The influence of CO 2 bubble collisions on mass transfer is measured and modeled with a modified Sherwood number correlation. Further visualization of the concentration field in the vicinity of O 2 bubbles by means of laser induced fluorescence shows the dependency of mass transfer from a chemical reaction and enables the development of a first model approach.

Description: Due to ship unloading and the change of downstream gas consumption, the BOG (Boil off Gas) and LNG output fluctuate constantly, causing difficulties in both design and operation of the BOG handling process. The high energy consumption, instability and inflexibility of the original process affect the operation cost and running safety of the terminal to a large extent. To address these problems, a BOG two-stage compression and recondensation process is designed and optimized based on the original one. Compared with the original process through dynamic simulation, the design process has better stability, which benefits from lower operating pressure and smaller fluctuations of both pressure and liquid level in recondenser. In addition, remarkable power and BOG emission are reduced, which brings great benefit and recover investment cost soon.

Description: A method for solvent screening and searching for additives in the field of physical absorption processes is presented. A model based on the concept of virtual components and on the concept of a simplified abstract flow sheet is created. An estimation procedure for thermodynamically consistent property sets for the virtual component is developed. The model is implemented into MATLAB ® . Its application is shown in two studies including a study for a solvent additive. Potential candidates can be characterized and ranges for properties of the solvent or additive are obtained by the means of the model. Conclusions obtained from the model support the screening process by a reduction of the number of further investigated components.

Description: A small scale demonstration plant was designed, set up and operated for the heterogeneously catalysed synthesis of biodiesel under supercritical conditions. An ASPEN plus model was applied to minimise the energy demand for the product purification stages, which were identified as the point of highest energy consumption of the process owing to the high molar excess of methanol required for the process (40:1 molar excess, 1.45:1 on a mass basis). Vacuum distillation followed by a small rectification column was identified as the optimum solution. The determination of the energy demand of the plant revealed the economic viability of the process as far as the energy consumption is concerned. The plant could be operated at full conversion of the feed (not raffinated rapeseed oil). The catalyst incorporated into the plant had been selected out of a large number of possible formulations through a screening procedure applying tricaprin as model substance. γ-Al 2 O 3 modified by acid treatment and La 2 O 3 supported by γ-Al 2 O 3 were identified as most promising candidates. The stability of these formulations was proven through long term stability tests. They revealed stable conversion for different feed stock such as raffinated rapeseed oil, not raffinated rapeseed oil and Used Cooking Oil (UCO), while for partially fermented rapeseed oil severe catalyst deactivation was observed after 250 h test duration.

Description: This paper describes a conceptual design for a Fischer–Tropsch (FT) reactor capable of providing the petroleum and hydrocarbon waste processing sectors with a low-cost and low-risk gas-to-liquids (GTL) technology for monetizing small-size gas sources. The reactor is easily scalable between 50 and 200 bbl day -1 of produced syncrude. An option for achieving a high conversion of syngas reactants with single-pass operation makes it suitable for processing the associated gas that is usually flared at oil exploration and production sites.

Description: Polylactic acid is produced industrially by ring-opening polymerization of lactide. Such a reaction is extremely sensitive to the level of monomer contaminants, thus posing some challenges for the operability of continuous processes. A control strategy was designed and the corresponding controller parameters were determined using gProms simulations by applying the Ziegler-Nichols, the Tyreus-Luyben, and the Cohen-Coon methods. Simulation results show that the proposed control strategy is effective in restoring the targeted process conditions after a sudden change in the level of contaminants, with the Cohen-Coon controller providing the better results. Additionally, the simulations demonstrate that the use of automatic process control reduces significantly the pressure rise along the reactors after a feed disturbance, thus ensuring a safer plant operation.

Description: When filling a tank with liquid via a tube, the tube may either reach nearly to the bottom of the tank or end at a certain distance above the bottom, allowing the liquid to splash into the tank from a certain height. Up to now, the electrostatic experts do not know exactly whether splash filling may create an electrostatic hazard or not. For this reason, the research project Splash Filling was started. The first part of this project has already been published in this journal [1]. This work is the second part of this project and answers the question, whether electrostatic discharges do occur during splash filling of several liters and which safety precautions may be necessary.

Description: Outdoor microalgal cultivation was carried out using 20-L tanks and sewage influent or effluent at an actual sewage treatment plant. The microalgae could be cultured by supplying only sewage influent or effluent without additional microalgal stock or nutrient salts. Adding air and CO 2 to the culture water promoted not only the cultivation of green algae, but also the consumption of nitrogen. Increasing the hydraulic retention time from 4 days to 10 days also promoted consumption and cultivation. In particular, adding CO 2 to the sewage influent achieved a 59-fold increase of the cell number of specific Scenedesmus species useful as components for fuel. The microalgae culture advanced even in the autumn/winter when the water temperature was 2.2–15.6°C. The higher heating values of microalgae cultivated with a hydraulic retention time of 10 days ranged from 18 to 20 kJ g –1 . No large difference in higher heating values of the small-sized floating microalgae and the large-sized settled microalgae was observed. The major organic components eluted by n -hexane were fatty acids such as palmitic and 11-hexadecenoic acid. The ratio of unsaturated fatty acids exceeded that of saturated fatty acids, possibly as a result of the fluidity of the cell membrane. The applicability of sewage culture microalgae to biofuel was demonstrated.

Description: Structured catalysts consisting of metal sheets on which Raney Ni was deposited by the thermal spraying method were tested for the liquid-phase hydrogenation of glucose to sorbitol and 2-nitrotoluene to 2-methylaniline, used as model reactions. Catalytic tests performed in a bench-scale (1 L) reactor have shown that catalytic activity of Raney Ni sheets is significantly higher than the one of the pellets used for fixed-bed applications but lower than the activity of the powder catalyst used in slurry mode. The activity could be significantly improved when applying a two-phase co-current flow through a monolith. In this case the activity was superior to the one obtained with the slurry catalyst. These results confirm the potential of Raney Ni monoliths as structured catalysts.

Description: The crystallization of two semicrystalline and water insoluble polymers with ester moieties, namely poly(ϵ-caprolactone) (PCL) and isotactic poly(methyl methacrylate) ( i -PMMA), was studied on the water surface using Langmuir trough measurements and Brewster angle microscopy. Additionally, Langmuir-Blodgett films were prepared and studied by atomic force microscopy. It was demonstrated that PCL forms distinct single crystals on the water surface with polymer chain orientation perpendicular to the water surface. i -PMMA behaved differently and crystallized upon compression on the water surface in a homogeneous layer with polymer chain orientation parallel to the water surface. In contrast, poly(ethylene oxide) (PEO) is a water soluble polyether and its crystallization at the air/liquid interface could only be studied when the water subphase was replaced with aqueous salt solutions containing kosmotropic salts according to the Hofmeister series.

Description: In this work, the content of flavonoids in GBE was increased successfully by anti-solvent recrystallization method (ASR) using ethanol as solvent and hexane as anti-solvent. By means of single factor method, the effect of main factors on the content of flavonoids in purified GBE was investigated. Under the optimal conditions, the content of flavonoids in purified GBE was increased from 23.60% to 53.85%, and the content of ginkgo terpene lactones in purified GBE was increased from 6.23% to 11.40%. In addition, the content of total ginkgolic acid of purified GBE was less to 10.00 ppm. Moreover, the morphology of raw GBE and purified GBE were characterized using scanning electron microscopy (SEM), observing that the particle size of purified GBE was much smaller than that of raw GBE. At the same time, the saturated solubility was increased from 149.84 µg mL -1 to 648.76 µg mL -1 .

Description: The solubility of commercially available natural gas in commercially available diesel fuel at room temperature and defined pressure is investigated experimentally. The gas phase is considered to be pure methane. The use of Henry's law to model the solubility is discussed. Solubility is given in terms of the mole fraction and the volumetric mass concentration of dissolved gas and the corresponding Henry's coefficients. The solubility is compared to that of pure methane in pure hexadecane, which is similar to diesel fuel with respect to the mean carbon number. Additional gaseous fuels can allow for reduced consumption of liquid fuels in combustion engines. Gas solubilities of a great number of pure materials have been investigated but many material mixtures of practical relevance have not been analyzed yet. The solubility of commercially available natural gas in commercially available diesel fuel was experimentally determined.

Description: Screening of the change mechanism of salicylic acid-4,4′dipyridyl (SAA-4,4′dipy) cocrystals to acetyl salicylic acid-4,4′dipyridyl (ASA-4,4′dipy) cocrystals was performed and their transformation investigated. Cocrystals of SAA-4,4′dipy are concomitantly formed in ASA/4,4′dipyridyl/ethanol solutions, resulting from ASA decomposition. Eventually, cocrystals of ASA-4,4′dipy are obtained from a sequence of in situ reactions by controlling the operating conditions. Both cocrystals have the same hydrogen bonding interaction between the drug molecules. The ketene functional group decomposed in salicylic acid cocrystal formation reaggregates during solution-mediated cocrystallization that leads to the formation of ASA cocrystals. Cocrystal forms of drugs are considered as promising alternatives to multicomponent conventional solid-state compounds since key solid-state properties of pharmaceuticals like solubility, stability, and dissolution rate can be modified. Supramolecular reaggregation of salicylic acid-4,4′dipyridyl cocrystals into ASA-4,4′dipyridyl cocrystals was induced by controlling the kinetic parameters.

Description: An experimental hydrodynamic investigation has been carried out for a novel internally circulating chemical looping (ICCL) reactor concept proposed to reduce the technical complexities encountered in conventional chemical looping combustion (CLC) and reforming (CLR) technologies. The concept consists of a single reactor with internal physical separations dividing it into two sections, i.e., the fuel and air sections. The trade-off for this reduction in process complexity is increased gas leakage between the two reactor sections, so a pseudo-2D cold-flow experimental unit was designed. The ICCL concept remains highly efficient in terms of CO 2 separation while ensuring significant process simplifications. The solids circulation rate also proved easy to control by adjusting the fluidization velocity ratio and the bed loading. In the light of the excellent hydrodynamic performance, the ICCL concept appears to be well-suited for further development as a CLC/CLR reactor model. An innovative internally circulating chemical looping reactor concept proposed to reduce the technical complexities in conventional chemical looping combustion and reforming technologies is experimentally investigated. The costs and solids handling challenges currently hampering the scale-up of chemical looping-based technologies are significantly diminished.

Description: The complicated interplay between mass and photon transfer within a photocatalytic reactor calls for an integrated design approach. This work presents a model-based optimization approach for LED-based photocatalytic reactors. First, a model that describes the distribution of reactants and photons within a photocatalytic reactor is developed. Second, several design variables related to the reactor dimensions and light sources are optimized simultaneously using the photocatalytic degradation of toluene as a model system. The results demonstrate how different formulations of the problem can be used to either minimize the reactor cost or to obtain a specified concentration profile within the reactor.

Description: A modified model coupled with the population balance equation has been developed to simulate the aggregation process in fluidized bed and the population balance equation is solved as part of computational fluid dynamics simulation by direct quadrature method of moments (DQMOM). In the simulation the aggregation rate is controlled by the aggregation kernel which is usually obtained by theoretical derivation and is difficult to verify experimentally. The main purpose of this article is to investigate the aggregation kernel by discrete element method and to test the performance of the new model for simulating cohesive particle flow in fluidized bed. Simulation results are compared to the experiment data and show good agreement. The comparison between different model is also carried out.

Description: Energy storage is needed for adjusting fluctuating renewable energies to the actual energy demand. A Liquid Organic Hydrogen Carrier (LOHC) system is examined for its suitability as a storage system for industrial applications. Integration of the LOHC system into e.g. a cement plant allows for optimized utilization of waste heat. The exhaust heat from the cement plant can increase the efficiency of the storage system. The efficiency of the LOHC system can be elevated by 12 percentage points. The working electricity costs of the cement plant can be significantly reduced by adding a LOHC storage system.

Description: Production of micro- to nano-sized particles of β-carotene was investigated using the solution-enhanced dispersion by supercritical fluids (SEDS) process. β-Carotene was dissolved in dichloromethane (DCM), n,n -dimethylformamide (DMF), n -hexane, or ethyl acetate, and supercritical CO 2 was used as an anti-solvent. The effects of the organic solvent, operating pressure, and temperature were examined. The morphologies of the particles produced by the SEDS were observed by field emission-scanning electron microscopy and particle sizes were determined by image analysis. Irregularly shaped micro particles were produced in the system which uses DCM and DMF solution. Plate-like micro particles were produced by using n -hexane solution, and irregular nanoparticles were produced by using ethyl acetate solution. The optimum operating conditions were determined to be ethyl acetate as solvent operated at 8–12 MPa and 40–60 °C.

Description: Through a dip-coating technique, carbon membranes were produced from a polymer blend consisting of the thermally stable polymer, polyetherimide (PEI) and the thermally labile polymer, polyethylene glycol (PEG). The PEG/PEI carbon membranes were synthesized on alumina support coated with an Al 2 O 3 intermediate layer. Results indicated that the polymer blend ratio and carbonization temperature influenced the structure and permeation performance of the derived carbon membranes. The porosity of the PEG/PEI carbon membranes increased with increasing of the PEG in the blends. Addition of 10 wt. % of the PEG to PEI (10 wt. % PEG:PEI) has increased the CO 2 permeability of the derived carbon membrane more than 3 times. However, the derived carbon membranes tended to lose the gas permeability with increasing of the carbonization temperatures from 600 to 700 °C. The carbon membrane derived from a 10 wt. % PEG:PEI blend ratio and carbonized at 650 °C afforded the highest CO 2 /CH 4 and CO 2 /N 2 selectivities, which were found to be 64.72 and 38.02 with the CO 2 , N 2 and CH 4 permeability of 211, 5.55 and 3.26 barrer, respectively.

Description: A novel TFC nanofiltration membrane containing hydrophilic organic additives was fabricated via interfacial polymerization method. To this end, three organic acids (lactic, maleic and citric acid) were applied as aqueous phase additives and their role in membrane structure and nanofiltration membrane flux enhancement was investigated. The FT-IR analysis confirmed the presence of organic acids in PA layer. The SEM and AFM analysis also were o applied to investigate membrane morphology. The more carboxylic functional group present in the additive resulted in the higher hydrophilicity and porosity and the more flux enhancement as the membrane containing 0.75w/w% citric acid show more than 50% increment rather than neat PA membrane, while the salt rejection was not sacrificed considerably.

Description: Aviation fuels derived from the Gas-to-Liquid (GTL) technology may be used as ‘drop-in’ alternatives to conventional oil-derived fuels. Towards that end, reliable composition-property relations must be developed based on experimental data to correlate the hydrocarbon compositions of formulated synthetic fuels with their properties to be certified for aviation commercial use. The certification of these fuels is governed by the American Society for Testing and Materials (ASTM) that defines jet fuels in terms of specific physical properties. This paper presents an experimental and property-integration framework for the design of synthetic jet fuels sourced from GTL-based kerosene derived by the evaluation of the role of aromatics on resultant fuel properties. The experimental campaign involved in this study was carried out at the Fuel Characterization Laboratory at Texas A&M University at Qatar. The results of the experimental campaign were used to develop property-mixing rules and linear programming for the design of optimum fuel compositions that meet the ASTM specifications. This study revealed the role of aromatics on critical physical properties for jet fuels certification as well as providing a practical solution for jet fuels blending through jet fuels optimization formulation based on cost and technical effective manners.

Description: The drive towards greater sustainability has prompted process industries to search for opportunities to decrease their production costs, energy consumption, equipment size, and environment impact as well as improve the raw material yields, remote control, and process flexibility. Process intensification (PI), which is defined as a set of innovative principles applied to the design of processes and equipment to satisfy all those concerns, has become the main trend for improving the process performance. PI is used widely in heat transfer, reactions, separation, and mixing, which results in plant compactness, cleanliness and energy efficiency. This paper reviews briefly some of the main intensified separation processes and improvement mechanisms. This study focused mainly on the PI of distillation processes, which are the most important separation methods. In addition to these technologies, the potential and reliability of reactive separation processes are addressed briefly, which will enable industry to achieve higher efficiency and high capacity. The recent developments in current research are summarized to highlight the importance as well as the effects, challenges, and future prospects of PI.

Description: The sorption of xylene and isooctane was measured by gravimetric flow sorption method on commercial activated carbons (virgin and reactivated ACs). Nitrogen physisorption, high-pressure mercury porosimetry, helium pycnometry, iodine number, pH measurement, Raman and X-ray photoelectron spectroscopies were used for textural, structural and surface characterization of ACs. The equilibrium geometries of isooctane and xylene molecules were modelled using DFT calculations and their dimensions were estimated to be correlated with textural properties of ACs to reveal the effect of size-selectivity. It was found out that the key factors influencing the adsorption capacity of chosen ACs for both tested volatile organic compounds (VOCs) are the mesopore surface area and the surface basicity.

Description: The handling of dispersed solids may lead to undesirable release of dust particles. Size and quantity of the particles transferred into the gas with time depend on the binding and separating forces in the powder. These in turn are determined by characteristic parameters of the powder and of the process. Analogous to the well-known “fractional collection efficiency” describing the dust separation, a newly defined “fractional release rate” to quantify the release of dust is introduced. The application is demonstrated by an example and the way to further development of this new approach is demonstrated.

Description: Thermally coupled distillation columns (TCDC) are used to reduce energy requirements on the separation of liquid mixtures, also reducing the environmental impact. The Petlyuk column is one of the TCDC with the highest reductions on heat duty. In this work, the use of distillation trains with Petlyuk columns is proposed to purify a multicomponent hydrocarbon mixture. Different sequences are studied, varying the location and number of Petlyuk columns to achieve separation of the components. Studied sequences are then optimized and compared in terms of energy requirements, environmental impact and dynamic performance. It has been observed that the stream on which the component with the highest feed composition is separated has a great influence on the total heat duty and environmental impact. Nevertheless, it appear to be a low correlation between location and number of Petlyuk columns in the sequences and their control properties.

Description: The aviation sector is nowadays looking for a biofuel to partially substitute the fossil fuel used for flights, namely jet fuel. Among the proposed processes for the production of the renewable jet fuel, the hydrotreating process has the better performance to the date. At the final stage of the hydrotreating process, a distillation train is required to obtain hydrocarbon fractions useful as fuels. Conventional or thermally coupled distillation sequences can be used in this step, and it can be expected that thermally coupled sequences require less energy to perform the separation. Nevertheless, in the selection of the best sequence for a given separation it is important to analyze its control properties. In this work a controllability analysis is performed for different distillation sequences used to obtain biofuels from a hydrocarbon renewable mixture, in order to detect the best sequence in terms of control properties.

Description: Marine cyanobacterium ( Oscillatoria sp., possibly a new species) isolated from the Sundarbans, the world's largest tidal mangrove forest, whose microbial diversity is being explored by Joydeep Mukherjee's research group. Photo: Courtesy of S. Chakraborty and V. Maruthanayagam.

Description: Oxidative coupling of methane is a low cost alternative for ethylene production. However, its high exothermicity, complex reaction network and low selectivity to C 2 products call for more in-depth analysis for economically viable process implementation. Microkinetic modelling enables assessment of operating conditions and catalyst properties on the overall performance via elementary gas-phase and catalytic reactions. The know-how to reproduce and interpret experimental kinetic data, especially the role of highly reactive intermediate species, is crucial for correct reaction network determination. Once the catalyst descriptors, physical catalyst properties and operating conditions are determined and optimized, next catalyst generations can be developed tailored to the process implementation.

Description: For the investigation of fluid dynamics from computed tomography (CT) images an evaluation method was developed that enables the data acquisition directly from the recorded CT images. Therefore a segmentation algorithm was implemented in Matlab to assign every component a specific gray value. A comparison of weight experiments with CT scans and following segmentation yield in good accuracy of this method. The liquid hold-up in different Mellapak 500.Y packings was determined through CT measurements and compared to predictive correlations from literature. 3D visualizations of short packing sections enable an evaluation of the liquid distribution and the flow morphology of the liquid in the packing. The common assumption of an even wetted packing surface with a constant liquid film thickness could not be shown in the experiments.

Description: Catalytic etherification of phenolic-oil with methanol was investigated to decrease the polarity and acidity of product oil. The catalyst of KH 2 PO 4 /AA showed a best performance due to its excellent dehydration and anti-coking property. When catalyzed by KH 2 PO 4 /AA, the content of aryl ethers increased with increasing temperature in low temperatures but decreased at 500 o C. Alkoxy phenols had an inhibiting effect to the etherification of alkyl phenols, because of adsorption competition. Aryl ethers were mostly generated from alkyl phenols, while alkoxy phenols were also contributive by simultaneous conversion to dialkoxybenzenes and diphenols parallelly, with a higher selectivity to diphenols. It explained the reduced alkoxy phenols and more generated alkyl phenols and aryl ethers at 350 o C.

Description: The nucleation and growth mechanisms of B polymorph of L-histidine (L-his) in a water-ethanol system were determined based on the induction time measurements. The induction times were experimentally determined at different supersaturations. The experimental results of induction time were correlated using the models of mononuclear and polynuclear mechanisms. The results showed that the primary nucleation mechanism of B polymorph of L-his is identified as a polynuclear mechanism, and the growth mechanism is identified as two-dimensional nucleation-mediated growth. These mechanisms of B polymorph of L-his will be used to characterize the polymorphic transformations and the overall crystallization rate of L-his.

Description: The permeability of a phosphoric acid hemihydrate crystal bed as well as the crystal yield and the crystal purity were studied in order to find a suitable operation range for the operation of a hydraulic wash column. The key parameters which were in the focus of this paper were the width of the crystals (as a measure of crystal size), the supersaturation and the stirring speed. The results show that a crystal bed which contains larger crystals gives a higher permeability. A higher supersaturation gives a higher crystal yield but more impurity inclusions in crystals. Last but not least, a higher stirring speed gives more impurity inclusions in crystals, too.

Description: Hydrocyclones are separators used in several industry fields, such as mining, food and petrochemical. Our research group designed a new hydrocyclone, in which a conical filtering wall replaces the conical section, producing another liquid stream leaving the equipment, besides underflow and overflow streams. In the present work, the influence of inlet diameter (Di) of a filtering hydrocyclone was analyzed by an experimental and CFD study. Data from conventional hydrocyclones of the same configurations were also obtained. Under the same operating conditions and geometry, the filtering hydrocyclone presented a better performance than the conventional device. Under the experimental conditions evaluated, an increase in inlet diameter by a factor of 2.2 reduces the Euler number by 84%.

Description: Chemical air scrubbers reduce the concentration of water soluble components such as ammonia from the outgoing ventilation air through absorption in water, followed by chemical conversions and removal of the end products. A mechanistic model for a countercurrent air scrubber was set up. Mass balances for ammonia, hydrogen sulphide, nitrous oxide and methane were implemented, as well as the water mass balance and heat balances. The model was validated against experimental data from a conventional fattening pig housing facility. The effect of influent characteristics, design parameters and control handles on the removal efficiency, the temperature profile and the water evaporation rate were investigated through simulation. The model was able to describe the behavior of a countercurrent chemical air scrubber.

Description: The egregious sensitivity of high energetic materials such as RDX and HMX has prompted efforts by researchers in the production of less sensitive explosives by crystallization without compromising performance. One such endeavour is crystal-size reduction to nano-scales. In this work, the optimum operating conditions for producing nano-sized RDX were determined from experiments. Based on these results, computational fluid dynamics (CFD) modelling and simulations were executed for scale up purposes and the identification of the influence of fluid dynamics, mixing and heat transfer on crystal growth and production rate on commercial scales. As a result, a commercial plant was designed and operation data from the commercial crystallizers compared with data obtained from scale up tasks.

Description: A coupled level set/volume of fluid (CLSVOF) method under the consideration of the rheological characteristics of fluid is employed to investigate numerically coalescence deformation of bubble pairs generating at two adjacent nozzles in carboxylmethylcellulose (CMC) aqueous solutions. The considerably satisfactory agreement between numerical results and experimental measurements approves the validity of this approach in predicting bubble surface evolution. The simulated results show that bubble coalescence process involves four stages of independent growth, rapid mergence, radial expansion and vertical stretching, respectively. The various effects of surfactant concentration, gas flowrate, nozzle spacing and nozzle diameter on the aspect ratio depend highly on each coalescence period.

Description: In this study, the effect of shear work at the solid boundaries is considered to analyze the heat transfer characteristics in the slip flow region for gaseous flow. Two different cases such as: parallel plates and micropipe is considered for the analysis. The fluid flow between parallel plates and micropipe is assumed to be laminar, incompressible, steady, hydrodynamically and thermally fully developed. The effect of second order velocity slip, temperature jump, shear work at the solid surface and viscous dissipation is considered for the analysis. The constant heat flux boundary condition is used at the surface of the parallel plates and micropipe. Closed form expressions are obtained for the temperature distribution and Nusselt number as the function of various modeling parameters for both the geometries. Present predictions are verified for the cases that neglect microscale effects and the effect of viscous heating, shear work, and a good agreement is observed with other existing theoretical results. Results show that neglecting shear work under predicts the Nusselt number.