scholarly journals Comparison of Experimental Results to CFD Models for Blending in a Tank Using Dual Opposing Jets

2011 ◽  
Author(s):  
Robert A. Leishear ◽  
Si Y. Lee ◽  
Mark D. Fowley ◽  
Michael R. Poirier ◽  
Timothy J. Steeper
Keyword(s):  
Liquid Radioactive Waste ◽  
Scale Up ◽  
Pilot Scale ◽  
Full Scale ◽  
Experimental Results ◽  
Cfd Models ◽  
Waste Storage ◽  
Scale Models ◽  
Computational Fluid Dynamics Cfd ◽  
Cooling Coils

Research has been completed in a pilot scale, eight foot diameter tank to investigate blending, using a pump with dual opposing jets. The jets re-circulate fluids in the tank to promote blending when fluids are added to the tank. Different jet diameters and different horizontal and vertical orientations of the jets were investigated. In all, eighty five tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of several miles of two inch diameter, serpentine, vertical cooling coils below the liquid surface for a full scale, 1.3 million gallon, liquid radioactive waste storage tank. Two types of tests were performed. One type of test used a tracer fluid, which was homogeneously blended into solution. Data were statistically evaluated to determine blending times for solutions of different density and viscosity, and the blending times were successfully compared to computational fluid dynamics (CFD) models. The other type of test blended solutions of different viscosity. For example, in one test a half tank of water was added to a half tank of a more viscous, concentrated salt solution. In this case, the fluid mechanics of the blending process was noted to significantly change due to stratification of fluids. CFD models for stratification were not investigated. This paper is the fourth in a series of papers resulting from this research (Leishear, et.al. [1–4]), and this paper documents final test results, statistical analysis of the data, a comparison of experimental results to CFD models, and scale-up of the results to a full scale tank.

scholarly journals Comparison of Experiments to Computational Fluid Dynamics Models for Mixing Using Dual Opposing Jets in Tanks With and Without Internal Obstructions

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
Robert A. Leishear ◽  
Si Y. Lee ◽  
Mark D. Fowley ◽  
Michael R. Poirier ◽  
Timothy J. Steeper
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Experimental Testing ◽  
Liquid Radioactive Waste ◽  
Correction Factors ◽  
Time Data ◽  
Cfd Models ◽  
New Findings ◽  
Computational Fluid Dynamics Cfd ◽  
Cooling Coils

This paper documents testing methods, statistical data analysis, and a comparison of experimental results to computational fluid dynamics (CFD) models for blending of fluids, which were blended using a single pump designed with dual opposing nozzles in an 8-foot-diameter tank. Overall, this research presents new findings in the field of mixing research. Specifically, blending processes were clearly shown to have random, chaotic effects, where possible causal factors, such as turbulence, pump fluctuations, and eddies, required future evaluation. CFD models were shown to provide reasonable estimates for the average blending times, but large variations—or scatter—occurred for blending times during similar tests. Using this experimental blending time data, the chaotic nature of blending was demonstrated and the variability of blending times with respect to average blending times was shown to increase with system complexity. Prior to this research, the variation in blending times caused discrepancies between CFD models and experiments. This research addressed this discrepancy and determined statistical correction factors that can be applied to CFD models and thereby quantified techniques to permit the application of CFD models to complex systems, such as blending. These blending time correction factors for CFD models are comparable to safety factors used in structural design and compensate variability that cannot be theoretically calculated. To determine these correction factors, research was performed to investigate blending using a pump with dual opposing jets, which recirculate fluids in the tank to promote blending when fluids are added to the tank. In all, 85 tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of vertical cooling coils below the liquid surface for a full-scale, liquid radioactive waste storage tank. Also, different jet diameters and different horizontal orientations of the jets were investigated with respect to blending. Two types of blending tests were performed. The first set of 81 tests blended small quantities of tracer fluids into solution. Data from these tests were statistically evaluated to determine blending times for the addition of tracer solution to tanks, and blending times were successfully compared to computational fluid dynamics (CFD) models. The second set of four tests blended bulk quantities of solutions of different density and viscosity. For example, in one test, a quarter tank of water was added to three quarters of a tank of a more viscous salt solution. In this case, the blending process was noted to significantly change due to stratification of fluids and blending times increased substantially. However, CFD models for stratification and the variability of blending times for different density fluids were not pursued, and further research is recommended in the area of blending bulk quantities of fluids. All in all, testing showed that CFD models can be effectively applied if statistically validated through experimental testing, but, in the absence of experimental validation, CFD models can be extremely misleading as a basis for design and operation decisions.

Model-based evaluation of a new upgrading concept for N-removal

2002 ◽  
Vol 45 (6) ◽  
pp. 169-176 ◽  
Author(s):  
S. Salem ◽  
D. Berends ◽  
J.J. Heijnen ◽  
M.C.M. van Loosdrecht
Keyword(s):  
Mathematical Modelling ◽  
Scale Up ◽  
Treatment Plant ◽  
Ammonia Concentration ◽  
Pilot Scale ◽  
Full Scale ◽  
Model Based ◽  
N Removal ◽  
Quantitative Basis ◽  
Treatment Concepts

Mathematical modelling is considered a time and cost-saving tool for evaluation of new wastewater treatment concepts. Modelling can help to bridge the gap between lab and full-scale application. Bio-augmentation can be used to obtain nitrification in activated sludge systems with a limited aerobic sludge retention time. In the present study the potential for augmenting the endogenous nitrifying population is evaluated. Implementing a nitrification reactor in the sludge return line fed with sludge liquor with a high ammonia concentration leads to augmentation of the native nitrifying population. Since the behaviour of nitrifiers is relatively well known, a choice was made to evaluate this new concept mainly based on mathematical modelling. As an example an existing treatment plant (wwtp Walcheren, The Netherlands) that needed to be upgraded was used. A mathematical model, based on the TUDP model and implemented in AQUASIM was developed and used to evaluate the potential of this bioaugmentation in the return sludge line. A comparison was made between bio-augmentation and extending the existing aeration basins and anoxic tanks. The results of both modified systems were compared to give a quantitative basis for evaluation of benefits gained from such a system. If the plant is upgraded by conventional extension it needs an increase in volume of about 225%; using a bioaugmentation in the return sludge line the total volume of the tanks needs to be expanded by only 75% (including the side stream tanks). Based on the modelling results a decision was made to implement the bioaugmentation concept at full scale without further pilot scale testing, thereby strongly decreasing the scale-up period for this process.

PILOT -SCALE, HIGH-STRENGTH INDUSTRIAL WASTEWATER TREATMENT EVALUATION BY MATHEMATICAL MODELLING

1994 ◽  
Vol 30 (3) ◽  
pp. 119-128
Author(s):  
Elemér Dobolyi ◽  
Imre Takács
Keyword(s):  
Wastewater Treatment ◽  
Treatment Plant ◽  
Pilot Scale ◽  
Full Scale ◽  
Phosphate Removal ◽  
Experimental Results ◽  
Plant Performance ◽  
Design Parameters ◽  
Plant Design ◽  
Effluent Standards

An existing rendering plant wastewater treatment facility has to be upgraded to meet the newly set British and more stringent EC effluent standards. After detailed analysis it turned out, that the existing treatment plant cannot be upgraded, a new plant has to be built. The rendering plant processes slaughterhouse wastes. The wastewater contains easily biodegradable organic substances, mainly organic acids, organic bonded nitrogen and ammonia. According to the new effluent standards the main task, besides the organic removal was the complete removal of nitrogen. The aim of this study was to find out the best available technology and the basic wastewater design data. For this purpose, on site pilot scale experiments were carried out. In several test runs the influent BOD and T K N have varied of between 1400-5500 and 460-1120 mg/l, respectively. Based on the experimental results, single-sludge nitrification-denitrification technology was selected for the full scale treatment plant. The plant was extended by chemical phosphate removal applying the post-precipitation method. In addition to the experimental schedule, a mathematical model of the plant was developed for two purposes.– to verify the applicability of the general activated sludge model under high concentration influent conditions, and– to generalize experimental results and provide a tool to predict plant performance under full scale conditions. On the basis of successful pilot plant experiments and model calibration, full scale plant design parameters were determined and presented. The full scale plant is under construction.

scholarly journals Theoretical and Practical Issues That Are Relevant When Scaling Up hMSC Microcarrier Production Processes

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Valentin Jossen ◽  
Cedric Schirmer ◽  
Dolman Mostafa Sindi ◽  
Regine Eibl ◽  
Matthias Kraume ◽  
...  
Keyword(s):  
Stem Cells ◽  
Scale Up ◽  
Human Mesenchymal Stem Cells ◽  
Scaling Up ◽  
Pilot Scale ◽  
Culture Broth ◽  
Cell Therapies ◽  
Computational Fluid Dynamics Cfd ◽  
Cell Densities ◽  
Stirred Bioreactors

The potential of human mesenchymal stem cells (hMSCs) for allogeneic cell therapies has created a large amount of interest. However, this presupposes the availability of efficient scale-up procedures. Promising results have been reported for stirred bioreactors that operate with microcarriers. Recent publications focusing on microcarrier-based stirred bioreactors have demonstrated the successful use of Computational Fluid Dynamics (CFD) and suspension criteria (NS1u,NS1) for rapidly scaling up hMSC expansions from mL- to pilot scale. Nevertheless, one obstacle may be the formation of large microcarrier-cell-aggregates, which may result in mass transfer limitations and inhomogeneous distributions of stem cells in the culture broth. The dependence of microcarrier-cell-aggregate formation on impeller speed and shear stress levels was investigated for human adipose derived stromal/stem cells (hASCs) at the spinner scale by recording the Sauter mean diameter (d32) versus time. Cultivation at the suspension criteria providedd32values between 0.2 and 0.7 mm, the highest cell densities (1.25 × 106cells mL−1hASCs), and the highest expansion factors (117.0 ± 4.7 on day 7), while maintaining the expression of specific surface markers. Furthermore, suitability of the suspension criterionNS1uwas investigated for scaling up microcarrier-based processes in wave-mixed bioreactors for the first time.

Evaluation of flow hydrodynamics in a pilot-scale dissolved air flotation tank: a comparison between CFD and experimental measurements

2015 ◽  
Vol 72 (7) ◽  
pp. 1111-1118 ◽  
Author(s):  
B. Lakghomi ◽  
Y. Lawryshyn ◽  
R. Hofmann
Keyword(s):  
Pilot Scale ◽  
Solid Particles ◽  
Cfd Model ◽  
Two Phase ◽  
Dissolved Air Flotation ◽  
Cfd Models ◽  
Three Phase ◽  
Computational Fluid Dynamics Cfd ◽  
Air Flotation ◽  
Dissolved Air

Computational fluid dynamics (CFD) models of dissolved air flotation (DAF) have shown formation of stratified flow (back and forth horizontal flow layers at the top of the separation zone) and its impact on improved DAF efficiency. However, there has been a lack of experimental validation of CFD predictions, especially in the presence of solid particles. In this work, for the first time, both two-phase (air–water) and three-phase (air–water–solid particles) CFD models were evaluated at pilot scale using measurements of residence time distribution, bubble layer position and bubble–particle contact efficiency. The pilot-scale results confirmed the accuracy of the CFD model for both two-phase and three-phase flows, but showed that the accuracy of the three-phase CFD model would partly depend on the estimation of bubble–particle attachment efficiency.

Scale-Up Problems

1982 ◽  
Vol 14 (9-11) ◽  
pp. 1269-1277
Author(s):  
John M Sidwick
Keyword(s):  
Wastewater Treatment ◽  
Scale Up ◽  
Pilot Scale ◽  
Full Scale ◽  
Bench Scale ◽  
Treatment Processes

The paper considers some of the problems of the scale-up of wastewater treatment processes; from bench-scale to pilot-scale, and from pilot-scale to full-scale. An attempt is made to put the question of scale-up problems into perspective by reference to the experience of the author and the work of others reported in the literature.

Combustion Characteristics of Fuels: Experiment Scale-Up From Bench Scale Reactors to Commercial Scale CFB Boiler

2005 ◽  
Author(s):  
Heidi Ha¨sa¨ ◽  
Ari-Pekka Kirkinen ◽  
Antti Tourunen ◽  
Timo Hyppa¨nen ◽  
Jaakko Saastamoinen ◽  
...  
Keyword(s):  
Dynamic Behavior ◽  
Dynamic Models ◽  
Scale Up ◽  
Combustion Process ◽  
Pilot Scale ◽  
Full Scale ◽  
Small Scale ◽  
Bench Scale ◽  
Precise Knowledge ◽  
Dynamic Experiments

The equipment scale-up towards larger CFB units requires accurate knowledge of the process and combustion behavior of fuels. Unit sizes of 300 MWe are in operation and plans for larger units have been made. Shift from natural circulation to once through steam cycle requires more precise knowledge of the dynamic behavior of the fuel since there is no steam drum. The combustion of inhomogeneous fuels, as well as, special demands for dynamic process behavior poses new challenges to boiler manufactures. Nowadays, dynamic models are used to develop and analyze the dynamic behavior of the combustion process. Testing all the dynamic changes in the full-scale reactor would be both expensive and risky. Therefore, bench and pilot scale experiments, combined with dynamic models of the combustion processes, give a good basis to study behavior of larger scale units. At the same time models also increase knowledge of different process relations. The main objective of this paper is to present results of scale-up experiments from the bench scale, via pilot scale, to full-scale boilers. Further, how the combustion and reactivity of fuels in the full-scale boilers can be studied with the aid of small-scale experiments and simulations. Dynamic experiments were carried out with three reactors of different scale. Calculation and simulation models have been developed to illustrate the combustion in the reactors; e.g. heat release profiles, fuel reactivity and particle size distribution. Results from the dynamic experiments are used to adjust the computer models.

scholarly journals Inerting Strategy for a Demonstration-Scale Hot Cell Facility Based on Experiences from Pilot-Scale Argon Cell Facility Operation and CFD Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Seungnam Yu ◽  
Jaehoon Lim ◽  
Ilje Cho ◽  
Jonghui Han
Keyword(s):  
Flow Rate ◽  
Cfd Simulation ◽  
Scale Up ◽  
Pilot Scale ◽  
Process Equipment ◽  
Successful Operation ◽  
Study Results ◽  
Computational Fluid Dynamics Cfd ◽  
Gas Tight ◽  
Practical Constraints

Pyroprocessing is being developed at Korea Atomic Energy Research Institute (KAERI), and in recent years, all process equipment required for integrated processes have been examined in the PyRoprocess-integrated Inactive DEmonstration (PRIDE) facility. Based on the successful operation of a pilot-scale facility, a conceptual design for this scale-up facility was actualized. Implementing a “demonstration-scale” hot cell facility is challenging as it is intended to supersede PRIDE and satisfy the increased requirements of larger-scale facilities. This study focused on an inerting strategy for a larger-scale (demonstration-scale) hot cell facility to achieve conditions equivalent to those in a pilot-scale gas-tight argon cell facility. The study applies the inerting strategy to a demonstration-scale hot cell facility beyond that of the currently existing pilot-scale hot cell facility and performs computational fluid dynamics (CFD) simulation with various flow rates to determine an appropriate approach for inerting the target facility. To this end, practical constraints on the simulation are introduced based on experiences from the existing pilot-scale facility. The results show that the purging flow rate should be accurately predicted, and a variable flow rate should be applied to achieve hot cell inerting effectively. The required purging time and amount of inerting source are essential factors in the larger-scale hot cell facility. The study results can be helpful in the design of large hot cell facilities operated under inert conditions.

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