Design and scale-up of Venturi-tube gas distributors for bubble column reactors

1991 ◽  
Vol 56 (3) ◽  
pp. 619-635 ◽  
Author(s):  
Jindřich Zahradník ◽  
Milan Rylek
Keyword(s):  
Bubble Column ◽  
Scale Up ◽  
Vessel Diameter ◽  
Energy Dissipation Rate ◽  
Venturi Tube ◽  
Small Scale ◽  
Process Conditions ◽  
Gas Dispersion ◽  
Industrial Reactor ◽  
Real Process

General principles of ejector distributors performance are surveyed and demonstrated for two particular cases of Venturi tubes commonly employed for gas dispersion in tower reactors with forced liquid circulation. Design recommendations for the two types of Venturi-tube gas distributors are presented and a general method is outlined for ejector distributors scale-up, based on the decisive effect of energy dissipation rate on the distributors performance. As an illustration, the specific case of Venturi-tube gas distributor design for an industrial reactor for catalytic hydrogenation of rape-seed oil is treated in detail. The procedure included design of a small-scale laboratory reactor for kinetic experiments at real process conditions (scale-down step) and subsequent ejector distributor scale up to dimensions corresponding to the industrial reactor (vessel diameter 1.6 m, effective reactor volume ~ 5 m3). Comparison with other modes of gas dispersion proved superiority of Venturi-tube distributors both on the laboratory- and industrial-scale level, regarding the overall rate of reaction process achieved and/or catalyst load requirements.

scholarly journals Using an acoustic levitator to investigate the drying kinetics and solids forming process of individual droplets during spray drying

2020 ◽  
Author(s):  
Ramona Huelsmann ◽  
Guenter J. Esper ◽  
Reinhard Kohlus
Keyword(s):  
Surface Temperature ◽  
Spray Drying ◽  
Scale Up ◽  
Small Sample ◽  
Drying Kinetics ◽  
Process Conditions ◽  
Drying Process ◽  
Real Process ◽  
Wide Range ◽  
Acoustic Levitator

AbstractSpray drying is a widely used process to turn slurries into dry powders and is especially important for thermally-sensitive materials, that are often found in the food or pharmaceutical industry. However, detailed insight into the drying kinetics during spray drying is difficult to investigate due to the boundary conditions in a spray drying tower. As a result, there is a lack of important information on the drying process and subsequent solidification of individual droplets. In this context, an experimental setup for a droplet positioned in a stationary ultrasonic field of an acoustic levitator is designed to enable a non-contacting measurement of the drying kinetics and the subsequent solidification process. To generate a comparable situation like in a real spray drying process, the droplet is positioned in an airflow, where air temperature, humidity, and velocity can be adjusted over wide range. Using an infrared camera to measure the surface temperature and a Complementary Metal Oxide Semiconductor (CMOS) camera for object recognition, the droplet can be observed continuously and drying kinetics of the droplet can be determined from the measured surface temperature and decreasing droplet size. Result of a 10 wt.% aqueous micro particle TiO2 suspension are reported and show that the investigated method is a very valuable and fast tool to safely scale-up spray drying systems very close to real process conditions. Especially when only small sample amounts are available in an early development stage.

Energy dissipation rate in a baffled vessel with pitched blade turbine impeller

1991 ◽  
Vol 56 (9) ◽  
pp. 1856-1867 ◽  
Author(s):  
Zdzisław Jaworski ◽  
Ivan Fořt
Keyword(s):  
Energy Dissipation ◽  
Cross Sections ◽  
Mechanical Energy ◽  
Vessel Diameter ◽  
Energy Dissipation Rate ◽  
Mean Velocity ◽  
Agitated Vessel ◽  
Radial Profiles ◽  
Pitched Blade Turbine ◽  
Turbine Impeller

Mechanical energy dissipation was investigated in a cylindrical, flat bottomed vessel with four radial baffles and the pitched blade turbine impeller of varied size. This study was based upon the experimental data on the hydrodynamics of the turbulent flow of water in an agitated vessel. They were gained by means of the three-holes Pitot tube technique for three impeller-to-vessel diameter ratio d/D = 1/3, 1/4 and 1/5. The experimental results obtained for two levels below and two levels above the impeller were used in the present study. Radial profiles of the mean velocity components, static and total pressures were presented for one of the levels. Local contribution to the axial transport of the agitated charge and energy was presented. Using the assumption of the axial symmetry of the flow field the volumetric flow rates were determined for the four horizontal cross-sections. Regions of positive and negative values of the total pressure of the liquid were indicated. Energy dissipation rates in various regions of the agitated vessel were estimated in the range from 0.2 to 6.0 of the average value for the whole vessel. Hydraulic impeller efficiency amounting to about 68% was obtained. The mechanical energy transferred by the impellers is dissipated in the following ways: 54% in the space below the impeller, 32% in the impeller region, 14% in the remaining part of the agitated liquid.

scholarly journals Solid Form and Phase Transformation Properties of Fexofenadine Hydrochloride during Wet Granulation Process

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 802
Author(s):  
Suye Li ◽  
Hengqian Wu ◽  
Yanna Zhao ◽  
Ruiyan Zhang ◽  
Zhengping Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Water Content ◽  
Scale Up ◽  
Small Scale ◽  
Dissolution Behavior ◽  
Wet Granulation ◽  
Water Addition ◽  
Granulation Process ◽  
And Performance

The quality control of drug products during manufacturing processes is important, particularly the presence of different polymorphic forms in active pharmaceutical ingredients (APIs) during production, which could affect the performance of the formulated products. The objective of this study was to investigate the phase transformation of fexofenadine hydrochloride (FXD) and its influence on the quality and performance of the drug. Water addition was key controlling factor for the polymorphic conversion from Form I to Form II (hydrate) during the wet granulation process of FXD. Water-induced phase transformation of FXD was studied and quantified with XRD and thermal analysis. When FXD was mixed with water, it rapidly converted to Form II, while the conversion is retarded when FXD is formulated with excipients. In addition, the conversion was totally inhibited when the water content was <15% w/w. The relationship between phase transformation and water content was studied at the small scale, and it was also applicable for the scale-up during wet granulation. The effect of phase transition on the FXD tablet performance was investigated by evaluating granule characterization and dissolution behavior. It was shown that, during the transition, the dissolved FXD acted as a binder to improve the properties of granules, such as density and flowability. However, if the water was over added, it can lead to the incomplete release of the FXD during dissolution. In order to balance the quality attributes and the dissolution of granules, the phase transition of FXD and the water amount added should be controlled during wet granulation.

SUBMERGED CITRIC ACID FERMENTATION OF SUGAR BEET MOLASSES: INCREASE IN SCALE

1955 ◽  
Vol 1 (5) ◽  
pp. 299-311 ◽  
Author(s):  
R. Steel ◽  
C. P. Lentz ◽  
S. M. Martin
Keyword(s):  
Citric Acid ◽  
Scale Up ◽  
Aeration Rate ◽  
Small Scale ◽  
Acid Fermentation ◽  
Inoculum Level ◽  
Cross Sectional ◽  
Factors Affecting ◽  
Beet Molasses ◽  
Initial Ph

Factors affecting the production of citric acid in the submerged fermentation of ferrocyanide-treated beet molasses by Aspergillus niger were studied in 2.5 and 36 liter fermenters. The small fermenters were used to determine the effects of changes in sterilization technique, phosphate supplement, ferrocyanide treatment, inoculum level, initial pH, fermentation temperature, and aeration rate. The relation between ferrocyanide concentration and inoculum level was also studied. Four different samples of molasses were fermented successfully. An average yield of 8.2% citric acid (64% conversion) was obtained from 51 small-scale fermentations. Comparable yields were obtained in the large fermenters under comparable conditions. Most of the information obtained with the small fermenters was applicable to the larger-scale fermenters, but in the latter the fermentation was significantly more stable. Aeration was the main problem in the scale-up and aeration rates approximately double those calculated on a fermenter cross-sectional area basis were required for comparable results in the large fermenters.

Characterizing the epoxidation process conditions of canola oil for reactor scale-up

2015 ◽  
Vol 67 ◽  
pp. 364-372 ◽  
Author(s):  
Ewumbua M. Monono ◽  
Darrin M. Haagenson ◽  
Dennis P. Wiesenborn
Keyword(s):  
Canola Oil ◽  
Scale Up ◽  
Process Conditions

scholarly journals Sustainable Second-Generation Bioethanol Production from Enzymatically Hydrolyzed Domestic Food Waste Using Pichia anomala as Biocatalyst

2020 ◽  
Vol 13 (1) ◽  
pp. 259
Author(s):  
Ioanna Ntaikou ◽  
Georgia Antonopoulou ◽  
Gerasimos Lyberatos
Keyword(s):  
Food Waste ◽  
Second Generation ◽  
Scale Up ◽  
Pichia Anomala ◽  
Small Scale ◽  
Amylolytic Enzymes ◽  
Second Generation Bioethanol ◽  
Saccharification Efficiency ◽  
Ethanol Yields ◽  
Domestic Food

In the current study, a domestic food waste containing more than 50% of carbohydrates was assessed as feedstock to produce second-generation bioethanol. Aiming to the maximum exploitation of the carbohydrate fraction of the waste, its hydrolysis via cellulolytic and amylolytic enzymatic blends was investigated and the saccharification efficiency was assessed in each case. Fermentation experiments were performed using the non-conventional yeast Pichia anomala (Wickerhamomyces anomalus) under both separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) modes to evaluate the conversion efficiencies and ethanol yields for different enzymatic loadings. It was shown that the fermentation efficiency of the yeast was not affected by the fermentation mode and was high for all handlings, reaching 83%, whereas the enzymatic blend containing the highest amount of both cellulolytic and amylolytic enzymes led to almost complete liquefaction of the waste, resulting also in ethanol yields reaching 141.06 ± 6.81 g ethanol/kg waste (0.40 ± 0.03 g ethanol/g consumed carbohydrates). In the sequel, a scale-up fermentation experiment was performed with the highest loading of enzymes in SHF mode, from which the maximum specific growth rate, μmax, and the biomass yield, Yx/s, of the yeast from the hydrolyzed waste were estimated. The ethanol yields that were achieved were similar to those of the respective small scale experiments reaching 138.67 ± 5.69 g ethanol/kg waste (0.40 ± 0.01 g ethanol/g consumed carbohydrates).

scholarly journals Assessing market-based conservation governance approaches: a socio-economic profile of Indonesian markets for wild birds

Oryx ◽  
2011 ◽  
Vol 45 (4) ◽  
pp. 482-491 ◽  
Author(s):  
Paul Jepson ◽  
Richard J. Ladle ◽  
Sujatnika
Keyword(s):  
Native Species ◽  
Wildlife Conservation ◽  
Scale Up ◽  
Policy Instrument ◽  
Wild Birds ◽  
Small Scale ◽  
Poor Growth ◽  
Cultural Aspects ◽  
Depth Analysis ◽  
Conservation Governance

AbstractOne of the most difficult situations for conservation is where state capacity to regulate is weak, major corporate organizations are absent, and the population does not have a strong culture of wildlife conservation. All these apply to the hugely popular urban Indonesian pastime of keeping wild songbirds, thought to be responsible for rolling local extinctions of several native species. In such situations the introduction of a voluntary, market-based approach could interact with regulation to create new and more effective approaches to reducing the negative conservation impacts of the associated trade. Here we assess the potential of such an approach through an in-depth analysis of the socio-economic and cultural aspects of bird keeping. We project that overall the pastime contributes USD 78.8 million to the economies of the six cities surveyed, supporting a range of associated small-scale rural and urban livelihoods relating to the production of cages and collection of live bird food. Finally, we describe five general bird-breeding models with the capacity to scale up the production of captive-bred birds that may substitute for wild-caught conspecifics. Based on this information we argue that a market-based policy instrument that is capable of shifting bird-keeping trends from wild-caught birds to captive-bred alternatives would align easily with macro-policy agendas in Indonesia relating to pro-poor growth and the creation of more and better jobs. Such a policy instrument could provide exciting opportunities for conservationists to engage the interest and support of non-conservation sectors in Indonesia in efforts to conserve diminishing populations of wild birds.

scholarly journals Energy Production from Biogas: Competitiveness and Support Instruments in Latvia

2016 ◽  
Vol 53 (5) ◽  
pp. 43-53
Author(s):  
G. Klāvs ◽  
A. Kundziņa ◽  
I. Kudrenickis
Keyword(s):  
New Technologies ◽  
Local Economic Development ◽  
Renewable Energy Sources ◽  
Distribution Network ◽  
Scale Up ◽  
Electricity Production ◽  
Small Scale ◽  
Gas Distribution ◽  
Ex Post ◽  
The Impact

Abstract Use of renewable energy sources (RES) might be one of the key factors for the triple win-win: improving energy supply security, promoting local economic development, and reducing greenhouse gas emissions. The authors ex-post evaluate the impact of two main support instruments applied in 2010-2014 – the investment support (IS) and the feed-in tariff (FIT) – on the economic viability of small scale (up to 2MWel) biogas unit. The results indicate that the electricity production cost in biogas utility roughly corresponds to the historical FIT regarding electricity production using RES. However, if in addition to the FIT the IS is provided, the analysis shows that the practice of combining both the above-mentioned instruments is not optimal because too high total support (overcompensation) is provided for a biogas utility developer. In a long-term perspective, the latter gives wrong signals for investments in new technologies and also creates unequal competition in the RES electricity market. To provide optimal biogas utilisation, it is necessary to consider several options. Both on-site production of electricity and upgrading to biomethane for use in a low pressure gas distribution network are simulated by the cost estimation model. The authors’ estimates show that upgrading for use in a gas distribution network should be particularly considered taking into account the already existing infrastructure and technologies. This option requires lower support compared to support for electricity production in small-scale biogas utilities.

Sign in / Sign up

Export Citation Format

Share Document