Academic literature on the topic 'Precipitation fouling'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Precipitation fouling.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Precipitation fouling"
1
Amaral, M. C. S., H. V. Pereira, E. Nani, and L. C. Lange. "Treatment of landfill leachate by hybrid precipitation/microfiltration/nanofiltration process." Water Science and Technology 72, no. 2 (May 5, 2015): 269–76. http://dx.doi.org/10.2166/wst.2015.218.
Full textAbstract:
This paper describes a promising method to treat stabilized landfill leachate. Such method consists of a combination of chemical precipitation processes, a cost-effective technique with high potential to remove contaminants with foulant nature, microfiltration aimed at removing the produced precipitate and nanofiltration (NF) for final polishing. This study was carried out on a bench unit comprising a precipitation reactor associated with a submerged hollow-fiber microfiltration membrane module and a flat NF membrane cell operated in batch and continuous mode with a treating capacity of 0.1 L h−1. Combining these processes yielded a clear and colorless permeate and proved to be very efficient at removing organic and inorganic matter. The results showed the importance of membrane processes to ensure treated landfill leachate quality. Also the precipitation associated with microfiltration as a pretreatment process is able to guarantee low membrane fouling due to the significant retention of humic substances which are known for their high potential to cause NF membrane fouling.
2
Li, Wei. "The Performances of Internal Helical-Rib Roughness Tubes Under Fouling Conditions: Practical Cooling Tower Water Fouling and Accelerated Particulate Fouling." Journal of Heat Transfer 125, no. 4 (July 17, 2003): 746–48. http://dx.doi.org/10.1115/1.1571090.
Full textAbstract:
This paper addresses fouling in a family of seven copper helically ribbed tubes. Series of semi-theoretical linear fouling correlations for long term combined precipitation and particulate fouling (PPF) in cooling tower systems and for accelerated particulate fouling were developed.
3
He, Chang-wei, Hui Wang, Luo-chun Wang, Zi-yang Lou, Li Bai, Hai-feng Zong, and Zhen Zhou. "Fouling Identification for Nanofiltration Membrane and the Potential Reduction of Pollutants in the Leachate by Using Fe/Al/PAC Coagulation." Sustainability 13, no. 3 (January 21, 2021): 1114. http://dx.doi.org/10.3390/su13031114.
Full textAbstract:
The reduction in the fouling is an important way to maintain the steady operation for the nanofiltration (NF) process in leachate treatment. The fouling components from the real leachate treatment process were identified using a scanning electron microscope equipped with X-ray microanalysis (SEM-EDS), infrared spectroscopy (FTIR), atomic analysis and three-dimensional fluorescence (EEM) analysis, and the coagulation of Fe/Al/PAC was selected to reduce the potential pollutants in the leachate, to reduce the potential fouling. It was found that organic humic acid and calcium-magnesium precipitates were the main pollutants in NF fouling. The foulant layer was the result of the combination of organic matter, inorganic precipitation, colloids and microorganisms, and the colloids precipitation is more important, and should be removed in advance. PAC was found to be more efficiency to reduce the colloids and the inorganic matter, among the coagulants selection, with the chemical oxygen demand (COD) removal rate of 55.1%. The commercially available coagulant-poly aluminum chloride (PAC) was chosen as a coagulant. The removal rate of leachate reached 55.1%, and the flow rate through the membrane was increased by 35.8% under the optimum condition (pH was 5.0, PAC dosage was 100 mg/L, and the membrane pressure was 0.4 MPa). Through the pilot scale test, the effluent was connected to the microfiltration membrane and then to the nanofiltration membrane and the practical engineering application is feasible.
4
Xuefei, Miao, Xiong Lan, Chen Jiapeng, Yang Zikang, and He Wei. "Experimental study on calcium carbonate precipitation using electromagnetic field treatment." Water Science and Technology 67, no. 12 (June 1, 2013): 2784–90. http://dx.doi.org/10.2166/wst.2013.161.
Full textAbstract:
The present study investigated the effectiveness of electromagnetic fields in preventing calcium carbonate (CaCO3) fouling in cooling water. Four different frequencies and two different voltages were adopted to induce electromagnetic fields directly in water with constant water temperature and constant flow velocity. Artificial hard water was used. The solution conductivities decreased by 17–25% from their initial values in the electromagnetic anti-fouling treatment (EAT) cases, depending on different frequencies of electric pulses, whereas the untreated case dropped by 31%. The particle size became small and the crystal structure changed into loose style after EAT. The EAT device independently developed by the State Key Laboratory had been validated as an effective apparatus in preventing CaCO3 fouling in cooling water.
5
Sheriff, M., and M. Gehr. "Laboratory Investigation of Inorganic Fouling of Low Pressure UV Disinfection Lamps." Water Quality Research Journal 36, no. 1 (February 1, 2001): 71–92. http://dx.doi.org/10.2166/wqrj.2001.005.
Full textAbstract:
Abstract Iron(III) (mainly dosed as FeCl3) is one of the main inorganic constituents associated with the fouling of UV lamps during disinfection of wastewater. A low pressure mercury lamp UV system was operated under laboratory conditions to assess the effects of heat and UV light on fouling. Iron(III) was dosed at different concentrations and fouling was monitored by measuring the UV irradiance. The potential for ferric phosphate fouling and the effects of organics were also studied. Results showed that fouling did not occur in recirculating systems over 12 days of observation. However, in flow-through systems, the extent and rate of fouling depended on the solution Fe concentration. Furthermore, addition of phosphorus increased the fouling rate. Bulk precipitation appeared to be significant at iron(III) dosing over 3 mg/L. Theoretical predictions of an equilibrium model (MINEQL+) showed similar trends with measured concentrations of soluble Fe and P from batch tests. However, model predictions of temperature effects alone could not account for the observed solids deposition on the quartz sleeve. Bulk precipitation, followed by sedimentation, was considered to be the dominant mechanism at high iron (III) concentrations.
6
Schäfer, A. I., A. G. Fane, and T. D. Waite. "Direct coagulation pretreatment in nanofiltration of waters rich in organic matter and calcium." Water Supply 1, no. 4 (June 1, 2001): 25–33. http://dx.doi.org/10.2166/ws.2001.0063.
Full textAbstract:
Nanofiltration (NF) can remove natural organic matter (NOM) and multivalent ions from surface waters. Large hydrophobic organics and calcium ions are responsible for irreversible fouling of nanofiltration membranes and thus a decrease of process efficiency and increase in cleaning requirements. Fouling due to the precipitation of organic-calcium complexes and the impact of colloids and coagulant (FeCl3) on the precipitation of these species was investigated. Coagulation in solution (as opposed to in the boundary layer) did not cause significant flux decline and was able to prevent irreversible fouling under conditions which were previously determined as detrimental. The rejection was varied if a strongly charged solid was deposited on the membrane.
7
Cho, Young I., Chunfu Fan, and Byung-Gap Choi. "THEORY OF ELECTRONIC ANTI-FOULING TECHNOLOGY TO CONTROL PRECIPITATION FOULING IN HEAT EXCHANGERS." International Communications in Heat and Mass Transfer 24, no. 6 (October 1997): 757–70. http://dx.doi.org/10.1016/s0735-1933(97)00063-8.
Full text
8
Wang, Yuan, Chao Shen, Zhenbo Tang, Yang Yao, Xinlei Wang, and Benjamin Park. "Interaction between particulate fouling and precipitation fouling: Sticking probability and deposit bond strength." International Journal of Heat and Mass Transfer 144 (December 2019): 118700. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2019.118700.
Full text
9
Zou, Long Sheng, De Zhen Chen, and Wei Guo Zhou. "Numerical Simulation of SiO2 Fouling While Evaporating High Concentration Extracted Oil Wastewater." Advanced Materials Research 518-523 (May 2012): 3231–35. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.3231.
Full textAbstract:
This article aims at fouling situation while extracted oil wastewater evaporating and has analyzed the change process in wastewater SiO2. We point out influence of the formation of fouling SiO2pre-condition—supersaturation and establish SiO2crystallization precipitation model and equation. The results show that concentration ratio and evaporation temperature increase to help fouling formation to give rise to fouling heat resistance elevating. The increase of extracted oil wastewater flow rate loop reduce the fouling heat resistance and improve the efficiency of heat utilize. Through simulation , we master main influencing factors of fouling heat resistance and grain a good foundation to design the experiment scheme in the future.
10
Sheng, Jian, and Hua Zhang. "Precipitation Characteristics of CaCO3 Scaling on Stainless Steel in Cooling Tower Condition." Applied Mechanics and Materials 226-228 (November 2012): 1029–33. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.1029.
Full textAbstract:
Stainless steel 304 and 316 (ss304 and ss316) are widely used in heat exchangers, and the precipitation characteristics of CaCO3 is the first step to research anti-fouling technology. CaCO3 scaling precipitated on coupons from 1.0mmol/l CaCO3 solution at 35°C. By weighing the coupons before and after static reaction experiments to get the mass of scaling and the morphology was taken by Scanning Electron Microscope (SEM). The results show that at the same condition there is more fouling on ss304 than ss316. Higher pH not only promotes square aragonite and calcite and square aragonite gradually recrystallize to calcite but also makes both homogeneous and heterogeneous nucleation rate increasing, and the former increases more, so the fouling mass is bigger at lower pH than higher pH; fouling grows at the place with higher surface energy first and then extend to surrounding place, and when the number increases and crystals grow big and connect each other to form fouling layer.
Dissertations / Theses on the topic "Precipitation fouling"
1
Michaud, Maïté. "Contacteur membranaire innovant pour la cristallisation : application aux systèmes de type diffusion / réaction." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1322.
Full textAbstract:
Les procédés membranaires sont considérés comme l’une des technologies de rupture les plus prometteuses pour les opérations de cristallisation/précipitation. Les matériaux les plus exploités à ce jour sont poreux mais leurs limitations en terme de bouchage de pores et de mouillage entravent le bon déploiement du procédé. L’utilisation de matériaux denses permettrait de s’affranchir de ce phénomène de colmatage des pores tout en conservant les bénéfices apportés par les procédés membranaires. Dans une première partie expérimentale, le composé modèle choisi, le BaCO3, est précipité dans un contacteur membranaire gaz-liquide et liquide-liquide, opéré dans les deux cas en conditions statiques. Cette configuration permet de s’affranchir de l’influence de l’hydrodynamique. Les interactions membranes-cristaux sont étudiées sur divers matériaux polymères denses. La perméabilité des espèces réactives et la tension de surface sont les deux paramètres ayant un impact majeur sur la localisation de la précipitation et la capacité à décrocher les cristaux déposés de la surface du matériau. Le PDMS et le Teflon AF 2400 ont été retenus comme étant les deux matériaux les plus prometteurs pour l’application visée car ils ne présentent pas de colmatage interne et de surface. Une deuxième partie expérimentale a été menée en conditions dynamiques sur le même composé modèle, en système gaz-liquide. Des modules membranaires de fibres creuses autosupportées (PDMS) et de fibres creuses composites (PP-Teflon AF 2400) ont été utilisés. Les études réalisées sur l’influence des paramètres opératoires ont présenté des résultats semblables à ceux des contacteurs membranaires utilisés pour le captage du CO2 : la résistance au transfert de matière est majoritairement localisée dans la phase liquide. Les performances stables obtenues sur le module PP-Teflon AF 2400 d’une compacité de 10 % ont permis de valider le concept. La géométrie du module, en particulier sa compacité, est un critère primordial pour limiter le colmatage du module. Enfin, une modélisation de mécanique des fluides en 2D, par la méthode des éléments finis, a été menée. Le modèle repose sur l’ajustement d’un seul paramètre cinétique. Les profils de concentration simulés ne sont pas satisfaisants. En revanche, le modèle permet de prédire correctement la productivité des cristauxMembrane processes are considered as one of the most promising breakthrough technology for crystallization/precipitation operations. Porous materials have been extensively investigated but they have shown some serious limitations due to pore blocking and wetting phenomenon. The use of a dense membrane is expected to circumvent the pore blocking issue while keeping the advantages of membrane processes. In a first part, the model compound, BaCO3, is precipitated within a gas-liquid or liquid-liquid membrane contactor working under static conditions for both systems. In this configuration, hydrodynamic influences are avoided. The membrane-crystals interactions are studied using several dense membrane polymers. Permeability of both reactant species and surface tension are the key parameters to be considered. Indeed, these parameters greatly affect the deposit location of the crystals and their adherence on the membrane surface. Fouling within the membrane and on the surface are prevented with PDMS and Teflon AF 2400 which are thereby the two most promising materials for the given application. In a second part, the same model compound is precipitated in gas-liquid system under dynamic conditions. Self-supporting (PDMS) and composite hollow fibers (PP-Teflon AF 2400) are studied. Investigations on the operating condition influences show similar results to those obtained with membrane contactor used for CO2 capture: resistance to mass transfer is mainly located in the liquid phase. Proof of concept is supported by the stable performances obtained with the PP-Teflon AF 2400 module of 10 % packing ratio. The module geometry, and more specifically its packing ratio, is an important criterion to take into account to avoid module blocking. Finally, 2D computational fluid dynamics simulations, using the finite element method are performed. One single kinetic parameter is used to fit the experimental data. The simulated concentration profiles are not satisfactory. Nonetheless, predictability of the model seems to be promising: crystal productivities are rather well estimated
2
Singh, Atmajeet. "Heat exchanger fouling by precipitation of calcium phosphates." Thesis, 1992. http://hdl.handle.net/2429/3057.
Full textAbstract:
The fouling characteristics of artificially hardened waters containing calcium and
orthophosphate ions were investigated. The water was circulated through a steam heated double
pipe heat exchanger under turbulent flow conditions. Inlet water temperatures were about 20 to
25°C and the phosphate content about 100 ppm. Experiments were carried out to ascertain the
effects of pH, velocity, surface temperature and concentrations of the calcium and the
orthophosphate on the fouling process. The fouling behaviour was recorded in terms of the
fouling resistance-time curve which was calculated from the time dependence of the overall heat
transfer coefficients. Under the constant heat flux condition imposed, the fouling resistance was
generally linear in time; however, asymptotic fouling was observed in some cases.
The fouling rate was found to be a very strong function of the pH over the range 6.5 to
8.0. The rate was also found to be exponentially dependent on the calculated surface
temperature. The initial fouling rate increased linearly with the velocity and with the
concentrations of scale forming species. Deposit thickness increased with heated length of the
stainless steel test section. In most cases, the deposit was a dense crystalline scale, which had
a Ca/P molar ratio of 1.35±0.15. The results are discussed in terms of the ionic equilibrium
involved and the solubility and crystallisation kinetics from the literature. It is apparent that the
rate of phosphate precipitation is influenced both by surface reaction and mass transfer in the
range of the variables studied. Findings are compared with the few prior phosphate fouling
studies from the literature. Scale density is reported, and its thermal conductivity estimated using
the fouling resistance measurements.
3
E, Hong. "Instability, precipitation and fouling in heavy oil systems." Thesis, 2005. http://hdl.handle.net/2429/17028.
Full textAbstract:
Asphaltenes are the most polar, highest molecular mass species found in crude oils and
bitumens. Depending on the nature of the surrounding species, the temperature and pressure,
asphaltene may be dissolved, or may flocculate resulting in precipitation.
Asphaltene precipitation during oil production and processing is a very serious problem in
many areas throughout the world. To avoid precipitation, much research has been directed to
the solubility of asphaltenes in petroleum liquids as a function of temperature, pressure and
composition. Bitumen from oil sands deposits contains about 13.5% asphaltenes, and during its
processing is mixed with low molecular mass diluents, which can lead to precipitation and to
fouling of processing equipment.
In this work, the effects of diluent composition on asphaltene precipitation from Cold Lake
vacuum residue (VR) and Athabasca atmospheric tower bottoms (ATB) were determined using
the hot filtration method at 60-85°C. The selected diluents include pure n-alkanes (heptane,
decane and dodecane), a lube oil basestock—paraflex (PFX), a heavy vacuum gas oil (HVGO)
and a resin enriched fraction (REF) recovered from Cold Lake vacuum residue by supercritical
fluid extraction and fractionation. The latter three complex diluents were tested alone and in
blends, in order to cover a range of saturates from 56 to 99.4wt%, aromatics from 0.6 to
25wt%, and resins from 0 to 19wt%. For pure n-alkanes, the amount of asphaltene precipitation
at a given diluent/residue ratio decreases as the molecular mass of n-alkanes increases. With the
increase of diluent-to-residue ratios R, the amount of precipitated asphaltene, W, increases
sharply at first and then levels off. Similar behaviour can be found for the mixtures of both
feedstocks with the aliphatic diluent PFX. With more aromatic diluents such as pure HVGO or
blends of HVGO/PFX=l, the increases in W with R are modest or slight within the range of
experiment. The addition of the resin and aromatic-rich REF has a strong inhibition effect on
asphaltene precipitation. For selected mixtures, the temperature effect on precipitation was
investigated in the range of 60°C to 300°C. The results indicate that for the mixtures used in
this work the solubility of asphaltenes increases monotonically with temperature.
Asphaltene solubility and precipitation using simple diluents has been analyzed traditionally
using thermodynamic models; however, these models are based on the assumption that
asphaltene precipitation is a reversible process. This has been a controversial issue, and because
of lack of precise experimental data, it has remained unresolved. Another approach is a scaling
model based on aggregation of clusters. The original form of scaling equation proposed by
Rassamdana et al. gave good agreement of the precipitation data as a function of R for the pure
n-alkane diluents (heptane, decane and dodecane). For the complex multi-component diluents
of this work, an extended scaling equation with two additional variables (the density and
saturate content of the diluents) was developed and provided good agreement with the data over
a wide range of diluents to feed ratios. The scaling equation was also extended to correlate
asphaltene precipitation from different feed oils by incorporating the colloidal instability index
(CII) of the feed oil. This extended scaling equation correlates the experimental data from the
two different feed oils well for both single and multi-component diluents. The scaling equation
can also be put into a form more useful for thermal fouling studies by converting the ratio W to
the precipitated asphaltene concentration (g precipitated asphaltene/L mixture) in the mixture.
The effects of different diluents on the stability of colloidally dispersed heavy oil systems
were tested by determining asphaltene precipitation onset points by titration. Cold Lake
vacuum residue (VR), Athabasca atmospheric tower bottoms (ATB) and Cold Lake heavy oil
(HO) were selected as sources of asphaltene. The diluents included toluene, Paraflex (PFX),
heavy vacuum gas oil (HVGO), resin enriched fraction (REF), de-asphalted oil (DAO) and fuelApplied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
4
Gavril, Marcela. "Precipitation fouling of heat exchangers by magnesium (calcium) silicates." Thesis, 2001. http://hdl.handle.net/2429/11528.
Full textAbstract:
Fouling due to deposition of inverse solubility salts in cooling water systems is
one of the major problems in chemical process industries. Deposition of calcium
silicates as well as magnesium silicates can be a problem; however, literature
information on both solubility data and fouling results for silicate containing
cooling waters is sparse. In this work the effects of varying pH, concentrations of
silicate and liquid velocity on the fouling process were investigated for both
calcium and magnesium salts.
Experiments were carried out with aqueous solutions containing either calcium or
magnesium chloride and sodium silicate re-circulated at a bulk temperature of
25°C through a steam heated exchanger for periods up to 24 hours. The steam
temperature was raised from about 106°C during fouling to maintain a constant
heat flux. Magnesium (or calcium) was maintained in excess, with silicate
concentrations in the range of 33 to 130 ppm as SiO32-. Over the range of
conditions tested extent of fouling was low, and results were subject to
considerable scatter.
In the first set of experiments the velocity, heat flux, and concentration of
reactants were kept relatively constant. The pH of the artificial cooling water
was varied . For calcium solutions results after 6 hours of operation were
scattered, with Rf values of 0.1 m²K/kW at pH 9 and 10.8 and much lower values
at pH 11. For magnesium solutions the extent of fouling increased steadily with
pH over the range 7-9, over 24 hour runs. Trends with pH are compared with
results from previous literature. Experiments were carried out to study the effect
of silicate concentration on the fouling process, both at constant magnesium
concentration and at constant SiO3/Mg mol ratio. With velocity, pH and heat flux
kept relatively constant, the silicate concentration was varied . The extent of
fouling was found to increase with the silicate concentration over the range 33 to
130 ppm SiO3, irrespective of the magnesium concentration. The final set of
experiments was carried out in order to determine the effect of velocity on the
fouling rate. The rate of fouling appeared to go through a maximum with
increasing velocity; however, additional experimentation is required to confirm
this effect. Partial deposit analyses at pH from 8 to 9 indicated an SiO2/MgO
mass ratio of 1.4±0.2, compared to 1.5 expected for pure MgSiO3. Deposits were
a sticky yellow-brown solid, often with a mud-like consistency.
Results are compared with literature guidelines for pH, magnesium and silicate
concentrations to minimize fouling.
5
Demirskyy, O., P. O. Kapustenko, G. L. Khavin, O. P. Arsenyeva, O. Matsegora, S. Kusakov, and I. Bocharnikov. "Investigation of fouling in plate heat exchanger at sugar factory." Thesis, 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/28163.
Full textBook chapters on the topic "Precipitation fouling"
1
Yu, Gu, Jin Bs, and Xiao G. "The Fouling Characteristics and Comparative Analysis of Cleaning Technology of SCR." In Electrostatic Precipitation, 624–26. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-540-89251-9_129.
Full text
2
Tsuge, Hideki, Yuko Tanaka, and Noriko Hisamatsu. "Fouling of Cheese Whey during Reverse Osmosis and Precipitation of Calcium Phosphate." In Progress in Biotechnology, 47–52. Elsevier, 2000. http://dx.doi.org/10.1016/s0921-0423(00)80011-8.
Full textConference papers on the topic "Precipitation fouling"
1
Zhang, Guanmin, Guanqiu Li, Wei Li, and David Kukulka. "Investigation of Precipitation Fouling in Corrugated Plate Heat Exchangers." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17076.
Full textAbstract:
Experimental and theoretical investigations of precipitation fouling performance have been performed inside four corrugated plate heat exchangers (PHE). They have different geometry parameters, such as plate height, plate spacing, and plate angle. Heat transfer coefficient and friction factor have been obtained in the clean tests with the range of Reynolds number of 600–6000. Three precipitation fouling experiments focused on temperature influences and geometric designs have been performed. PHE with the largest hydraulic diameter and height to pitch ratio shows the best anti-fouling performance. Scanning electron microscope is used to investigate the microscopic structures of precipitation fouling. A type of Teflon coated plate has been used for testing the anti-fouling characteristic of PHEs. The coated plates show well anti-fouling performance comparing with the common SS-304 plates. A semi-empirical fouling model using Prandtl analogy has been established. The model predictions agree well with experimental data.
2
Li, Wei. "Experimental Studies of Shell and Tube Condenser Fouling and Accelerated Particulate Fouling in Internal Helical-Rib Roughness Tubes." In ASME 2003 Heat Transfer Summer Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ht2003-47404.
Full textAbstract:
This paper addresses fouling in a family of seven 15.54 mm I.D. copper, helically ribbed tubes, which have different ridge heights, helix angles, and number of ridge starts. A series of semi-theoretical linear fouling correlations as a function of the product of area indexes and efficiency indexes for long term combined precipitation and particulate fouling (PPF) in cooling tower systems and a series of semi-theoretical linear fouling correlations as a function of the efficiency indexes for particulate fouling were developed. The correlations can be directly used to assess the fouling potential of enhanced tubes in actual cooling water situations.
3
Li, Wei, and Hongxia Li. "Numerical Analysis of Composite Fouling in Corrugated Plate Heat Exchanger." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17075.
Full textAbstract:
This paper provides a numerical analysis on precipitation and particulate fouling in a corrugated plate heat exchanger. This analysis started from the mass balance fouling model, and Realizable κ-ε model with non-equilibrium wall functions is used in the 3D numerical simulation considering the realistic geometries of the flow channel to obtained Nusselt number and wall shear stress, while Von-Karman analogy is used to obtain mass transfer coefficient. The numerical analysis is verified by experimental study. The predicted influence of fluid velocity in fouling resistance is compatible with experimental data that it can help to optimize the design of plate heat exchangers. The investigation significantly simplifies the fouling analysis of complex flow fields and can be used to assess the fouling potential of corrugated plate heat exchangers.
4
Farrell, Andrew Robert, Dario Marcello Frigo, Gordon Michael Graham, Robert Stalker, Ernesto Ivan Diestre Redondo, and María de la O. Masa Lorenzo. "Addressing Fouling by Qualifying Chemical Additives Using Novel Technologies." In Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/207980-ms.
Full textAbstract:
Abstract Fouling of heat exchangers and production of stable emulsions in desalting units can present significant challenges in refinery operations. Often these difficulties occur due to the concurrent processing of two or more crude oils that are incompatible under process conditions. This paper describes a significant development in laboratory techniques for studying these issues and evaluating mitigation strategies. Asphaltenes compatibility was evaluated for oil mixtures that may be co-processed in the refinery using a deposition flow rig, and the results were compared with those obtained with more conventional tests: blending stability analysis by light scattering and various screening methods. The flow rig mimics the process conditions (elevated pressure, high temperature, flow-induced shear) and identifies whether deposition or precipitation will occur. The former can cause fouling of heat exchangers whereas the latter produces solids that can stabilize emulsions in the desalter. By varying the proportions of oils that were co-injected into the deposition flow rig, the range within which mixtures were unstable was found. By flowing through a capillary (to mimic a heat exchanger) and in-line filter, it was possible to identify whether precipitation of suspended flocs or fouling of the heat exchanger itself was the likely issue for each mixture. Emulsion-stability tests were conducted using a pressurized rig with an ersatz separator to mimic the desalting unit; results were compared with those obtained in conventional, ambient-pressure bottle tests. Oil(s) and refinery wash water were injected, mixed under representative shear, and allowed to separate within the typical residence time of the desalter. Chemical additives were tested to identify those that were effective at controlling any observed problems. Results obtained in either flow rig (using representative pressure, temperature, and shear) did not always match those obtained using conventional methods. Asphaltenes fouling occurred under conditions where it was not predicted by screening tests that were conducted at conditions not representative of the process and did not occur under conditions where it was predicted. Differences were also observed between the emulsion stability observed in bottle versus rig tests, though these should be viewed as complementary techniques. This paper presents new laboratory techniques for the prediction and prevention of refinery fouling and emulsion stability. They mimic conditions in the facilities much better than those typically used to date.
5
Li, Wei. "Semi-Theoretical Modeling Oscillatory Fouling in Enhanced Tubes in Cooling Tower Systems." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32931.
Full textAbstract:
The fluctuation of fouling data, a well-known fouling phenomenon, was recognized in applications three decades ago, but it had not yet been well understood. Of specific interest is long term, combined precipitation and particulate fouling in cooling tower systems. Fouling data collected in seven 15.54 mm I.D. copper, helically ribbed tubes at water velocity (1.07 m/s) at practical conditions shows an oscillatory behavior. In order to observe it, a water temperature difference of 3.0°C, or greater, was needed for adequate accuracy based on an uncertainty analysis. Oscillatory model was used to analyze the data. The frequencies of the fluctuation are the same for the seven tested tube geometries. A series of semi-theoretical correlations of fluctuation of the long-term cooling tower water fouling data were developed. It was found that there are two ranges of amplitudes of the fluctuation based on internal parameters: linear range and non-linear range.
6
Fu, Ping, Hong-Xia Li, Wei Li, Yi-Lin Du, and Sheng-Lan Xiao. "Numerical Analysis of Cooling Tower Water Fouling in Enhanced Tubes." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17089.
Full textAbstract:
This paper provides particulate and precipitation fouling data in five 15.54 mm I.D. copper, helically ribbed tubes taken at the condition of Re = 16000 and 800 ppm concentration. The geometries of the helical-rib tubes provided a class of internal enhancement that is typical of commercially enhanced tubes presently used in water chillers, and the ranges of geometric parameters were number of rib starts (10 to 30), helix angle (25° to 45°), and height (0.40 to 0.55 mm). A semi-theoretical model was developed to investigate the main factors of fouling formation from the fouling tests. The fouling model which started from the mass balance model considered the influences of the mass transfer coefficient, wall shear stress, sticking probability and deposit bond strength factor. The model analysis results fit the experiment data well. 3D numerical models for the experimental tubes were established, in which volume-control method and standard k-ω model were used. To explain the diversity of anti-fouling performance in different tubes, the influences of velocity field near wall to the cooling tower fouling deposition were also discussed. It is found that the fouling resistance increases with the increase of the number of starts and helix angle. The numerical results had reasonable deviations with the experimental data.
7
Yang, Yong, Hyoungsup Kim, Andrey Starikovskiy, Alexander Fridman, and Young I. Cho. "Application of pulsed spark discharge for precipitation of calcium carbonate and prevention of mineral fouling in heat exchangers." In 2010 IEEE 37th International Conference on Plasma Sciences (ICOPS). IEEE, 2010. http://dx.doi.org/10.1109/plasma.2010.5534141.
Full text
8
Kastner, Johannes, Sara Fedier, Norbert Kockmann, and Peter Woias. "Reactive Precipitation in Microchannels: Impact of Convective Mixing on Particle Formation." In ASME 2007 5th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2007. http://dx.doi.org/10.1115/icnmm2007-30035.
Full textAbstract:
Reactive precipitation in micro- and minichannels currently draws attention of both, chemists and engineers in the field of micro process engineering. Due to intensified mixing and improved heat and mass transfer, fast chemical and thermodynamical processes involved in precipitation can be controlled readily in micro or mini structures. Particularly microchannels are a promising technology for particulate processes allowing continuous operation along with little or no backmixing. However, the sensitivity of microscale channels to blocking and fouling requires careful design and appropriate peripheral equipment. This study presents experimental results of barium sulfate precipitation from barium chloride solution and sulfuric acid in both, T-shaped and injection micromixers. The measured particle size distributions (PSD) are characterized by their first and second moment, reflecting the correlation between fluidic mixing and precipitation: faster mixing results in smaller mean particle sizes (1st moment of the PSD). The homogeneity of the mixing process on the other hand should have impact onto the width of the distribution (2nd moment of the PSD) due to superposition of locally formed particles to the global size distribution. The experimental particle size distributions are compared with simulations based on reduced-order modeling of the diffusive mixing process, coupled with the population balance for particle nucleation and growth. While the simulated size distributions have mean diameters between 40 nm and 68 nm, experimental data are between 90 nm and 130 nm.
9
Yang, Yong, Hyoungsup Kim, Jin M. Jung, Alexander Fridman, and Young I. Cho. "Application of Pulsed Spark Discharge for Mitigation of Mineral Fouling in a Heat Exchanger." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22392.
Full textAbstract:
One of the challenges in the production of electricity is the cooling water management because the calcium content in circulating cooling water continues to increase with time as pure water evaporates. Thus, the excessive mineral contents in water circulation systems could cause severe fouling in heat transfer equipment. To avoid the catastrophic failure in condensers, the cooling water is discharged after 3 cycles at a rate of 10 million gallons a day in a 1,000-MW thermoelectric power plant. The present study investigated the effect of pulsed spark discharges on the mitigation of mineral fouling in a concentric counterflow heat exchanger. Artificial hard water with calcium carbonate hardness ranging from 250 to 500 ppm was used with velocity varying over a range of 0.1–0.5 m/s and zero blowdown. Fouling resistances decreased by 50–88% for the plasma treated cases compared with the values for no-treatment cases. SEM photographs showed particle with larger sizes for the plasma treated cases comparing to smaller but more organized particles for the no-treatment cases. The different structures of particles were associated with pulsed spark discharge assisted precipitation of calcium carbonate in oversaturated hard water. X-ray diffraction data showed calcite crystal structures for all cases.
10
Scholl, Stephan. "From Batch to Continuous Production Through Micro Process Technology: Chances and Challenges." In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62028.
Full textAbstract:
The majority of the manufacturing processes in the chemical, pharmaceutical, food or cosmetics industry is operated as batch processes. This is economically advantageous in cases where - capacities per product are low, in the range of 10 kg/a to 1000 t/a - many different educts have to be mixed and processed for the product, i.e. a recipe-based manufacturing, - many different but similar products have to be produced, - educts have to be fed at different times and with varying quantities, - educts show problematic properties such as high viscosity, solids or stickiness, - problematic processing behaviour such as fouling, foaming, viscous intermediate phases or undesired precipitation, is found, - manufacturing has to meet a sometimes stochastic market demand or - the process consist of only a few process steps like mixing, heating, reaction and cooling.