Lower Feed Flow Rate Research Articles

Effect of drying technique and feed flow rate on bacterial survival and physicochemical properties of a non-dairy fermented probiotic juice powder

Drying of probiotic fruit juice can be a good alternative for new probiotic foodstuff production since most probiotic foods are dairy-based products, which are not suitable for people with galactosemia, lactose intolerance or allergy to milk protein. Thus, the aim of this study was to evaluate the influence of spray and spouted bed drying and feed flow rate on the microorganism survival and physicochemical properties of probiotic orange juice powder. Fermented probiotic orange juice containing Lactobacillus casei NRRL B-442 was spray-dried at 140 °C and spouted bed dried at 60 °C, respectively. Three different feed flow rates were studied for each equipment. Maltodextrin and gum Arabic were used as drying agents at 15% (w/w). The low temperature used in the spouted bed drying resulted in better probiotic bacteria viability compared to the product obtained by spray drying. Moisture and glass transition temperature were improved at the lowest feed flow rate (0.2 L/h), and faster rehydration time was achieved using maltodextrin. Thus, the spouted bed drying at low feed flow rates using maltodextrin as drying agent were the best parameters to produce powder fermented probiotic orange juice with high viability levels after drying and with good physicochemical parameters.

Negative chromatography of hepatitis B virus-like particle: Comparative study of different adsorbent designs

Purification of virus-like particles (VLPs) in bind-and-elute mode has reached a bottleneck. Negative chromatography has emerged as the alternative solution; however, benchmark of negative chromatography media and their respective optimized conditions are absent. Hence, this study was carried out to compare the performance of different negative chromatography media for the purification of hepatitis B VLPs (HB-VLPs) from clarified Escherichia coli feedstock. The modified anion exchange media, core-shell adsorbents (InertShell and InertLayer 1000) and polymer grafted adsorbents (SQ) were compared. The results of chromatography from packed bed column of core-shell adsorbents showed that there is a trade-off between the purity and recovery of HB-VLPs in the flowthrough fraction due to the shell thickness. Atomic force microscopic analysis revealed funnel-shaped pore channels in the shell layer which may contribute to the entrapment of HB-VLPs. A longer residence time at a lower feed flow rate (0.5ml/min) improved slightly the HB-VLPs purity in all modified adsorbents, but the recovery in InertShell reduced substantially. The preheat-treatment is not recommended for the negative chromatography as the thermal-induced co-aggregation of HCPs and HB-VLPs would flow along with HB-VLPs and thus reduced the HB-VLPs purity in the flowthrough. Further reduction in the feedstock concentration enhanced the purity of HB-VLPs especially in InertLayer 1000 but reduced substantially the recovery of HB-VLPs. In general, the polymer grafted adsorbent, SQ, performed better than the core-shell adsorbents in handling a higher feedstock concentration.

Comparison of hollow fiber module designs in membrane distillation process employed lumen-side and shell-side feed

In the present work, randomly packed, curly fiber, spacer scattered, and spacer knitted modules were fabricated and their performance in direct contact membrane distillation employed lumen-side feed and shell-side feed was investigated, respectively. Experimental results showed that the flux of different module configurations in shell-side feed operations were lower than that in lumen-side feed operations. Modified modules showed higher flux compared with randomly packed module and the spacer knitted module had the best performance with 51.8% enhancement at 328 K in lumen-side feed performance. The module flux increased as the feed flow rate increased, and all the modified modules showed relative high flux even at a low feed flow rate, which confirmed the fluid improvement caused by the spacers or wavy geometries. The overall heat transfer coefficient of modules ranged from 704 to 1,961 W/(m2 K) in lumen-side feed operations, while that was lower to be 425–645 W/(m2 K) in shell-side feed operations. In addition, higher heat transfer coefficients and temperature polarization coefficient were observed with modified module configurations. The sodium chloride tracer response technique was used to reveal the shell-side flow pattern and distribution for various module designs. Results showed that the modified module configurations can provide a better flow distribution in shell side with longer residence time and smaller variance, thus higher thermal efficiency and flux could be accomplished.

High gradient magnetic separation in centrifugal field

High gradient magnetic separation (HGMS) in centrifugal field, termed a Centrifugal High Gradient Magnetic Separation (CHGMS), has been developed to concentrate fine weakly magnetic particles such as hematite and ilmenite. In this investigation, the principle of CHGMS is theoretically discussed and a cyclic pilot-scale CHGMS separator was tested to concentrate a fine (−74μm) hematite ore, to study the effect of key variables such as magnetic induction, rotation speed of matrix, feed flow rate and feed mass on the separation performance of the separator. The results of investigation indicate that changes in the magnetic induction and the rotation speed of matrix had the most significant influences on the performance. An increase in the rotation speed improved concentrate grade but reduced iron recovery, while the reverse was observed for changing the magnetic induction. A too low feed flow rate resulted in an extremely high recovery but a lower concentrate grade. For a given matrix configuration, there was an upper limit for feed mass as the capture area of magnetic elements in the matrix was fixed, and this limit was correlated to the rotation speed of matrix. When the variables were optimized, the CHGMS separator achieved a superior separation performance to pulsating HGMS, achieving a separation efficiency of 72.50% compared to 56.41%, respectively. It was thus concluded that the CHGMS provides a potential technique for the production of high-grade magnetic concentrate from fine weakly magnetic ores.

Application of synthesized anion and cation exchange polymers to membrane capacitive deionization (MCDI)

In this study, sulfonated poly(phenylene oxide) (SPPO) and aminated polysulfone (APSf) were synthesized for use as a cation exchange polymer and an anion exchange polymer respectively. The resulting ion exchange capacities of SPPO and APSf of 0.93 and 1.0 respectively were almost equivalent to each other. Then the ion exchange polymers were coated onto the surface of commercial carbon electrodes. Membrane capacitive deionization (MCDI) performance using these coated electrodes was tested under various operating conditions such as adsorption/desorption time, feed flow rate, and feed NaCl concentration and compared with capacitive deionization (CDI) under the same conditions. The experimental results indicate that the effluent concentration during desorption becomes higher with increased adsorption time and a lower feed flow rate. Also it was shown that the introduction of both cation and anion exchange polymers was effective in preventing the “co-ion” effect. With MCDI, a salt removal efficiency of 100% was obtained under the conditions of 5 min/1 min adsorption/desorption time and 23 mL/min feed flow rate, while with CDI the salt removal efficiency was less than 40% under the same conditions. Open image in new window

A CFD Simulation of Hydrogen Production in Microreactors

In this study, the modeling of hydrogen production process in microreactors by methanol-steam reforming reaction is investigated. The catalytic reaction of methanol-steam reforming producing hydrogen is simulated considering a 3D geometry for the microreactor. To calculate diffusion among species, mixture average correlations are compared to Stephan-Maxwell equations. The reactions occurring inside the microreactor include reforming of methanol with steam, methanol decomposition, and a reaction between carbon dioxide and hydrogen. The main objectives of this study are the prediction of temperature profile along the microreactor using either mixture average method or Stephan-Maxwell one and the comparison between the present predictions and some existing experimental data. The simulation results indicate that Stephan-Maxwell method conforms more suitably to the experimental results. The difference is more at lower feed flow rates since, when the flow rate increases, mass transfer mechanism changes from diffusion to convection, which in turn reduces the difference.

An experimental investigation of biodiesel steam reforming

Recently, liquid biofuels have attracted increasing attention as renewable feedstock for hydrogen production in the transport sector. Since the lack of hydrogen infrastructure and distribution poses an obstacle for the introduction of fuel cell vehicles to the market, it is reasonable to consider using liquid biofuels for on-board or on-site hydrogen generation. Biodiesel offers the advantage of being an environmentally friendly resource while also having high gravimetric and volumetric energy density.The present study constitutes an experimental investigation of biodiesel steam reforming, the main emphasis of which is placed on finding optimum operating conditions in order to avoid catalyst deactivation. Temperature was varied from 600 °C to 800 °C, pressure from 1 bar to 5 bar and the molar steam-to-carbon ratio from 3 to 5. Based on the experimental results, coke formation and sintering are identified as the main deactivation mechanisms. Initiation of catalyst deactivation primarily depends on catalyst inlet temperature and feed mass flow per open area of catalyst. By using a metallic based precious metal catalyst, applying low feed flow rates (31 g/h∙cm2) and a sufficiently high catalyst inlet temperature (>750 °C) coking can be minimized, thus avoiding catalyst deactivation. A stable product gas composition close to chemical equilibrium has been achieved over 100 h with a biodiesel conversion rate of 99%.

Use of a DC discharge in a plasma reactor with a rotating ground electrode for production of synthesis gas by partial oxidation of methane

A recently designed rotating ground electrode plasma reactor has been used to produce synthesis gas by partial oxidation of methane at room temperature and atmospheric pressure without a catalyst. Experiments were performed to investigate the effects of feed flow rate, feed composition, and the presence of nitrogen in the feed. It was shown that increasing the O2-to-CH4 molar ratio reduces conversion of the reagents at low feed flow rates but promotes conversion at high feed flow rates. Increasing the O2-to-CH4 molar ratio also results in further methane partial oxidation reactions at high feed flow rates. Use of air instead of pure oxygen increases the conversion of methane and oxygen but reduces selectivity for the main products (H2 and CO). This reactor can be used to produce a wide variety of H2-to-CO molar ratios for different applications under stable conditions.

Using a wire coil insert for biodiesel production enhancement in a microreactor

In the present work, the application of wire coil to promote mixing in a microreactor during continuous production of biodiesel was studied. For this aim, soybean oil as a feedstock and potassium hydroxide as a homogeneous catalyzed were used. The influences of the various parameters such as geometric and operational conditions on the performance of biodiesel production were experimentally examined. Response surface methodology (RSM) in conjunction with the Box–Behnken method was used to statistically analyze and optimize the biodiesel production process. The comparison between two types of reactors (with and without wire coil) shows a significant enhancement in mixing during transesterification. The impacts of different wire coil lengths and wire coil pitchs on methyl ester conversion were also investigated. A reaction yield of 99% at the residence time of 180s was obtained in the modified microreactor. However, the measured pressure drop show that the microreactor equipped with wire coil consumed more energy. Therefore, performance ratio was defined to evaluate energy efficiency and the results show the advantage of using the wire coil insert in lower feed flow rates.

Experimental and modeling of a non-isothermal CSTR to find out parameter regions and conditions causing input multiplicity for acid catalyzed hydrolysis of acetic anhydride

The continuous stirred tank reactor (CSTR) presents challenging operational problems due to its complex open-loop non-linear behavior such as input and output multiplicities, ignition/extinction, parametric sensitivity, non-linear oscillations and perhaps even chaos. Many researchers have studied the non-linear dynamic behavior of CSTR for several reaction schemes from a theoretical stand point. The present experimental studies are carried out to identify the existence of input multiplicity in a non-isothermal CSTR. The sulfuric acid catalyzed hydrolysis of acetic anhydride reaction system has been chosen and the regions of existence of input multiplicity are theoretically identified. The reactor showed the same steady state temperature for two input flow rates of reaction mixtures into the CSTR reactor and thus confirming the existence of input multiplicity for the sulfuric acid catalyzed hydrolysis of acetic anhydride reaction system. It was observed that the time taken by the reactor was too long at a low feed flow rate of reaction mixture than at a higher feed flow rate reaction mixture. The model simulations of steady state temperatures were in close agreement with experimental data for the above feed flow rates of reaction mixture conditions.

Degradation of CO2 through dielectric barrier discharge microplasma

AbstractThe continually increasing use of fossil fuels throughout the world has caused carbon dioxide (CO2) concentration to grow rapidly in the atmosphere. Increasing CO2 emissions are the major cause of global warming, and a number of studies have been done to show the predicted effects of global warming. This paper reported a method of degradation of CO2 through dielectric barrier discharge (DBD) plasma; a microplasma reactor was used to decompose CO2 into carbon monoxide (CO) at normal atmosphere and room temperature. Gas chromatography was used to analyze the compositions of the outlet gases. No carbon deposits were found in this work. A variety of parameters, such as feed flow rate, input power, frequency, discharge gap, and external electrode length were investigated. The effects of these parameters on CO2 conversion were examined. At the same time, the effects of feed flow rate and input power on the energy efficiency were studied. The results indicated that a higher conversion of CO2 can be realized with a lower feed flow rate, a limited higher input power and a lower frequency. However, a higher feed flow rate and a lower input power were beneficial for energy utilization. The discharge gap had a little effect on the conversion of CO2 in microplasma reactor. In this work, the highest conversion of CO2 was 18.0%, and the highest energy efficiency was 3.8%. The DBD microplasma is a promising method for decomposing CO2.© 2014 Society of Chemical Industry and John Wiley & Sons, Ltd

The effects of spray drying process parameters on the characteristic process indices and rheological powder properties of microencapsulated plant (Gypsophila) extract powder

Gypsophila Saponaria afficinalis, is in the family Caryophyllaceae, native to southern Europe and southwest Asia, and commonly known as the soapworts. The aqueous extract was obtained by sequential extraction of soapwort plant roots and prior to spray drying operation maltodextrin was added as a carrier material to adjust the soluble solid content (°Bx) of the soapwort extract (15°Bx, 22.5°Bx, 30°Bx). Powder properties of the product and the characteristic process indices were determined after spray drying of soapwort extracts with different air inlet (110°C, 135°C, 160°C) and outlet temperatures (50°C, 65°C, 80°C) with the other process parameters being constant. The moisture content of the powders changed between 6.35% and 0.44% being mostly affected by increasing outlet temperatures. Productivity and drying rate showed a decreasing tendency as air outlet temperature increased since high outlet temperatures required low feed flow rates. Dissolution time and tapped density were determined as powder characteristics combined with foam producing capacity, color and morphological properties. In general, results showed that spray drying can satisfactorily be used for spray drying of soapwort root extracts with acceptable moisture and water activity of the powders and functional properties of the reconstituted powders.

Hydrogen Production in a Large Scale Water–Gas Shift Pd-Based Catalytic Membrane Reactor

Composite palladium and Pd-based membranes represent an appealing technology option to increase the CO conversion and the H2 recovery in the water–gas shift (WGS) reactor as a result of the continuous removal of hydrogen over the course of the reaction. Even though many studies have been performed in this area, their outcome typically represents a proof-of-concept involving reactors with small membrane area. The present study therefore addresses the scaling up of the process to obtain high hydrogen production rates through the use of large surface area, ∼0.02 m2, composite Pd membranes. Two thin, δ < 10 μm, defect-free composite membranes were prepared by the electroless plating method on porous stainless steel tubular supports and tested under pure gases and water–gas shift reaction conditions. Syngas similar to the actual gasifier reacting mixture (40% H2, 42.2% CO, and 17.8% CO2 and steam to carbon ratio varying between 2.5 and 3.5) was fed to the WGS catalytic membrane reactor (WGS-CMR) with a total flow rate up to 1.5 Nm3 h–1, 20 bar maximum pressure, and temperatures ranging 420–440 °C. In the presence of crushed catalyst, CO conversions higher than the equilibrium conversions were obtained within the entire gas hour space velocity (GHSV) range considered in the present study, for pressures between 7 and 20 bar. At a relatively low feed flow rate, GHSV = 1130 h–1, a maximum CO conversion of 98.1% was achieved, with a hydrogen recovery of 81.5% at 440 °C. On the other hand, at the highest GHSVs, the system appeared to be limited by the activity of the ferrochrome catalyst. At 20 bar of absolute pressure in the retentate side, 440 °C, and GHSV = 5650 h–1, the hydrogen production rate was found to be 5.6 Nm3 day–1. Remarkably high hydrogen purity, in excess of 99.97% and 99.2% for the two membranes, respectively, was achieved also in experiments performed with a retentate pressure of 20 bar.

Non-alcoholic beer—A new industrial process

This paper studies a new industrial process for producing non-alcoholic beer with a corrected natural flavour profile. The aroma compounds are obtained by pervaporation of the original beer. The operating conditions of this unit, using polyoctylmethylsiloxane/polyetherimide (POMS/PEI) composite membranes, are investigated. High permeation temperature and low feed flowrate are the most effective for maximizing the permeation flux and the equilibrium of the flavour profile. The aroma depleted beer stream is then added to the feed stream of an industrial unit of spinning cone column distillation for dealcoholization. In this unit, the beverage contacts counter-currently with a water vapour stream that strips the ethanol and other volatile aroma compounds from beer. After dealcoholization, the beer is blended with the extracted aroma compounds and with a fraction of original beer to achieve a non-alcoholic beer (ethanol lower than 0.5 vol.%) with a good flavour profile. This new industrial process proved to originate a dealcoholized beer with a taste very close to the original one.

Studies on accelerated deactivation of ruthenium-promoted alumina-supported alkalized cobalt Fischer-Tropsch synthesis catalyst

Abstract Accelerated deactivation of ruthenium-promoted alumina-supported alkalized cobalt (K-Ru-Co/γ-Al 2O 3) Fischer-Tropsch (FT) synthesis catalyst along the catalytic bed over 120 h of time-on-stream (TOS) was investigated. Catalytic bed was divided into three parts and structural changes of the spent catalysts collected from each catalytic bed after FT synthesis were studied using different techniques. Rapid deactivation was observed during the reaction due to high reaction temperature and low feed flow rates. The physico-chemical properties of the catalyst charged in the Bed #1 of the reactor did not change significantly. Interaction of cobalt with alumina and the formation of CoAl 2O 4 increased along the catalytic bed. Reducibility percentage decreased by 4.5%, 7.5% and 12.9% for the catalysts in the Beds #1, #2 and #3, respectively. Dispersion decreased by 8.8%, 14.4% and 26.6% for the catalysts in the Beds #1, #2 and #3, respectively. Particle diameter increased by 0.6%, 2.4% and 10.4% for the catalysts in the Beds #1, #2 and #3, respectively, suggesting higher rate of sintering at the last catalytic bed. The amount of coke at the last catalytic bed was significantly higher than those of Beds #1 and #2.

Optimization of Process Parameters for Spray Drying of Fermented Soy Milk

Generally used as an inexpensive source of high-quality protein with many other health-promoting properties, soy milk offers an interesting alternative when fermented. Fermentation with lactic acid bacteria brings about the value addition to soy milk, making a nutritious probiotic food product. Dehydration helps to achieve longer shelf life and easier transportation and storage, enabling wider distribution of the product. The present work pertains to optimization of process parameters for spray drying of fermented soy milk using response surface methodology (RSM). The process parameters studied include inlet air temperature, aspirator speed (air flow rate), feed flow rate, and atomization pressure. The experiments were designed using the central composite design tool. Residual moisture content was found to be low at higher inlet air temperature, lower feed flow rate, higher atomization pressure, and higher air flow rate. Porosity reduced with increased atomization pressure. Higher product yield was obtained at high air flow rate and low feed flow rate. The increase in the atomization pressure increases the cohesiveness between particles, resulting in reduced flowability. An increase in the inlet air temperature greatly reduces the viability and the isoflavone aglycone content in the product. Protein denaturation during the process was found to reduce the product solubility.

Capability of a falling film microstructured contactor for the separation of binary mixtures

The present study investigates evaporation and separation of a binary mixture of ethanol and n-propanol in a microstructured falling film contactor made from two electrically heated vertical plates grooved with straight microchannels and forming the sides of a common gas chamber.Experiments were performed at atmospheric pressure (101.3kPa) and various wall temperatures above the saturation temperature of the inlet binary mixture. Electrical heating fluxes ranged from 2 to 4kW/m2 and feed flowrate between 1 and 8g/min. The feed concentration was fixed around 46mol.% of ethanol.The results indicate that the microcontactor performances depend essentially on heat flux and feed flowrate and provide fundamental insight on critical values of these two factors. Analysis of the results point out that intermittent local dry-zone can occur at high heat flux or at low feed flow rate. This occurrence influences microcontactor performances which can be evaluated in terms of stripping efficiency and power of separation.

Ultrafiltration of oil-in-water emulsion: Comparison of ceramic and polymeric membranes

Ultrafiltration (UF) has been recognized as a highly attractive technique for the treatment of stable oil-in-water emulsions. This technique has proved to be more effective then conventional methods since it may produce a water phase of higher quality and an oil phase which can be recycled. However, low permeate fluxes due to membrane fouling still represent one of the main limitations for its extensive application. The aim of this paper is to further contribute to the investigations of mass transfer characteristics during UF of oil-in-water emulsions. The performance of a polymeric (polyaryletherketone) membrane and a ceramic (zirconia) membrane were compared under different parameters of the UF process. The permeate recirculation experiment showed that the ceramic membrane is sensitive to oil penetration at lower cross-flow velocities and higher transmembrane pressures. The optimal performance for the ceramic membrane was obtained at a lower feed flow rate and transmembrane pressure compared to the optimal values for the polymeric membrane. The comparison experiments with volumetric concentration of the feed were carried out at optimal operation conditions for each of the membranes in order to maximise their performance. While the polymeric membrane showed expected oil rejection variation consistent with surface layer formation, the ceramic membrane showed poor oil rejection at the beginning of the operation. Further investigations need to show if the poor initial oil rejection of the ceramic membrane can be reduced without losing proved advantages of ceramic membranes over polymeric membranes.

Dynamic Behavior of a PEM Fuel Cell During Electrochemical CO Oxidation on a PtRu Anode

The dynamic behaviour of a single PEM fuel cell (PEMFC) with a PtRu/C anode catalyst using CO containing H2 as anode feed was investigated at ambient temperature. The autonomous oscillations of the cell potential were observed during the galvanostatic operation with hydrogen anode feed containing CO up to 1000 ppm. The oscillations were ascribed to the coupling of the adsorption of CO (the poisoning step) and the subsequent electrochemical oxidation of CO (the regeneration step) on the anode catalyst. The oscillations were dependent on the CO concentration of the feed gas and the applied current density. Furthermore, it was found that with CO containing feed gas, the time average power output was remarkably higher under potential oscillatory conditions in the galvanostatic mode than during potentiostatic operation. Accompanying these self-sustained potential oscillations, oscillation patterns of the anode outlet CO concentration were also detected at low current density (<100 mA/cm2). The online measurements of the anode outlet CO concentrations revealed that CO in the anode CO/H2 feed was partially electrochemically removed during galvanostatic operation. More than 90% CO conversion was obtained at the current densities above 125 mA/cm2 with low feed flow rates (100–200 mL/min).

Ethylene Epoxidation over Alumina-Supported Silver Catalysts in Low-Temperature AC Corona Discharge

In this paper, the epoxidation of ethylene over different catalysts—namely Ag/(low-surface-area, LSA)α-Al2O3, Ag/(high-surface-area, HSA)γ-Al2O3, and Au–Ag/(HSA)γ-Al2O3—in a low-temperature corona discharge system was investigated. In a comparison among the studied catalysts, the Ag/(LSA)α-Al2O3 catalyst was found to offer the highest selectivity for ethylene oxide, as well as the lowest selectivity for carbon dioxide and carbon monoxide. The selectivity for ethylene oxide increased with increasing applied voltage, while the selectivity for ethylene oxide remained unchanged when the frequency was varied in the range of 300–500 Hz. Nevertheless, the selectivity for ethylene oxide decreased with increasing frequency beyond 500 Hz. The optimum Ag loading on (LSA)α-Al2O3 was found to be 12.5 wt.%, at which a maximum ethylene oxide selectivity of 12.9% was obtained at the optimum applied voltage and input frequency of 15 kV and 500 Hz, respectively. Under these optimum conditions, the power consumption was found to be 12.6 × 10−16 W s/molecule of ethylene oxide produced. In addition, a low oxygen-to-ethylene molar ratio and a low feed flow rate were also experimentally found to be beneficial for the ethylene epoxidation.