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Articles 2401 - 2430 of 2957

Full-Text Articles in Engineering

Crude Oil Fouling In A Pilot-Scale Parallel Tube Apparatus, B. D. Crittenden, S. T. Kolaczkowski, T. Takemoto, D. Z. Phillips Jul 2007

Crude Oil Fouling In A Pilot-Scale Parallel Tube Apparatus, B. D. Crittenden, S. T. Kolaczkowski, T. Takemoto, D. Z. Phillips

Heat Exchanger Fouling and Cleaning VII

Maya crude oil fouling reveals a seemingly straightforward dependency of initial fouling rate on surface temperature but a maximum is found in the initial fouling rate – velocity relationship which mirrors that found in a model chemical system of styrene polymerization. The linear dependency of the logarithm of the pre-exponential factor on apparent activation energy for the crude oil is also found in the styrene system. The apparent activation energy for the crude oil ranged from 26.4 kJ/mol at 1.0 m/s to 245 kJ/mol at 4.0 m/s. Such strong dependencies of apparent activation energy on velocity, even at high velocity, …

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Crude Oil Fouling: Petronas Refineries Experience, M.S. Rafeen, M.F. Mohamed, M.Z. Mamot, N.A. Manan, Dr A. Shafawi, Dr M. Ramasamy Jul 2007

Crude Oil Fouling: Petronas Refineries Experience, M.S. Rafeen, M.F. Mohamed, M.Z. Mamot, N.A. Manan, Dr A. Shafawi, Dr M. Ramasamy

Heat Exchanger Fouling and Cleaning VII

Managing crude oil fouling has been a challenge in PETRONAS refineries. Over the past several years, numerous initiatives have been conducted in order to have better control of the situation [1][2][3][4]. The control strategy currently implemented is to periodically clean the heat exchanger based on the heat exchanger monitoring parameter and supported by antifouling chemical injection program. A review was conducted in one of PETRONAS’ refineries in order to come up with a better fouling control strategy. The review is separated into two parts. Firstly, the plant operational data for two selected hot pre-heat exchanger trains was analyzed. From the …

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Scale Deposits In Porous Media And Their Removal By Edta Injection, J. Moghadasi, H. Müller-Steinhagen, M. Jamialahmadi, A. Sharif Jul 2007

Scale Deposits In Porous Media And Their Removal By Edta Injection, J. Moghadasi, H. Müller-Steinhagen, M. Jamialahmadi, A. Sharif

Heat Exchanger Fouling and Cleaning VII

Formation damage has been observed in several oil reservoirs and production equipment in Iranian oil fields. Laboratory and field testing confirmed that the primary cause of damage was the build-up of calcium carbonate, calcium sulfate and strontium sulfate scale either in the perforation tunnels or in the formation sandstone nears the wellbore. Conventional acid treatments could dissolve this scale, but scale precipitation from the spent acid caused rapid productivity decline. A scale removal treatment with Na2H2EDTA has been developed that can effectively dissolve scale and chelate the dissolved metal ions. Chelation of the dissolved scale prevents scale reprecipitation. This study …

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The Effect Of Fouling On Heat Transfer, Pressure Drop And Throughput In Refinery Preheat Trains: Optimisation Of Cleaning Schedules, E. M. Ishiyama, W. R. Paterson, D. I. Wilson Jul 2007

The Effect Of Fouling On Heat Transfer, Pressure Drop And Throughput In Refinery Preheat Trains: Optimisation Of Cleaning Schedules, E. M. Ishiyama, W. R. Paterson, D. I. Wilson

Heat Exchanger Fouling and Cleaning VII

Optimising cleaning schedules for refinery preheat trains requires a robust and reliable simulator, reliable fouling models and the ability to handle the thermal and hydraulic impacts of fouling. The interaction between thermal and hydraulic effects is explored using engineering analyses and fouling rate laws based on the ‘threshold fouling’ concept; the potential occurrence of a new phenomenon, ‘thermo-hydraulic channeling’ in parallel heat exchangers, is identified. The importance of the foulant thermal conductivity is highlighted. We also report the development of a highly flexible preheat train simulator constructed in MATLAB&#;/Excel&#;. It is able to accommodate variable throughput, control valve operation and …

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Formation Of Gum And Deposits In An Oxygenated Naphtha Stream, Yonghua Li, Paul Watkinson, Patricio Herrera, Feridoun Fahiminia, Morgan James Jul 2007

Formation Of Gum And Deposits In An Oxygenated Naphtha Stream, Yonghua Li, Paul Watkinson, Patricio Herrera, Feridoun Fahiminia, Morgan James

Heat Exchanger Fouling and Cleaning VII

Gums formed when organic fluids are in contact with air can cause fouling of process equipment. The oxidation and formation of gum in a naphtha stream was studied in a stirred batch reactor as a function of temperature (96 to 130ºC) and at a total pressure of 584 kPa. Mixtures of air and nitrogen in the pressurizing gas gave dissolved oxygen contents in the range 10-270 ppm wt. Peroxide and existent (dissolved) gum contents were measured over periods of up to 80 hours. Rates of reaction were low, with maximum concentrations of peroxide typically below 4 meq/L, and gum formation …

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Observation Of An Isokinetic Temperature And Compensation Effect For High Temperature Crude Oil Fouling, C. A. Bennett, R. S. Kistler, K. Nangia, W. Al-Ghawas, N. Al-Hajji, A. Al-Jemaz Jul 2007

Observation Of An Isokinetic Temperature And Compensation Effect For High Temperature Crude Oil Fouling, C. A. Bennett, R. S. Kistler, K. Nangia, W. Al-Ghawas, N. Al-Hajji, A. Al-Jemaz

Heat Exchanger Fouling and Cleaning VII

The initial fouling rates of four crude oils were determined at a nominal bulk temperature of 315 °C, an initial heated wall shear stress of 13 Pa, and initial surface temperatures between 375 and 445 °C. These initial fouling rates ranged from 1.3(10-6) to 7.8(10-5) m2 K/kJ. Corresponding Arrhenius plots were linear with the initial fouling rates passing through an isokinetic temperature of 407.5 °C. A plot of the natural logarithm of the preexponential factors (7.6(104) – 5.2(1015) m2 K/kJ) versus the apparent activation energies (128 – 269 kJ/mol) was also linear, confirming the validity of the isokinetic temperature and …

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Investigation Of The Mechanisms Of Heat Exchanger Corrosion In A Municipal Waste Incineration Plant By Analysis Of The Raw Gas And Variation Of Operating Parameters, C. Deuerling, J. Maguhn, H. Nordsieck, B. Benker, R. Zimmermann, R. Warnecke Jul 2007

Investigation Of The Mechanisms Of Heat Exchanger Corrosion In A Municipal Waste Incineration Plant By Analysis Of The Raw Gas And Variation Of Operating Parameters, C. Deuerling, J. Maguhn, H. Nordsieck, B. Benker, R. Zimmermann, R. Warnecke

Heat Exchanger Fouling and Cleaning VII

The detailed mechanism of high temperature chlorine corrosion, the dominant cause of corrosion in a municipal solid waste incinerator (MSI), has still to be clarified (Schroer, 2002). Upon its way through the boiler the raw gas is subject to various physical and chemical processes and interactions. Of these, sulphation of chlorides is supposed to have the major impact on chlorine corrosion (Neumann, 1997). The physical and chemical mechanisms of corrosion were investigated at a municipal solid waste incinerator. Both, the particulate and gas phase of the flue gas, were chemically and physically analyzed during their way through the boiler, at …

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Milk Protein Fouling In A Tubular Heat Exchanger: Effect Of Milk Temperature And Reynolds Number, D.H.G. Pelegrine, K.F. Oliveira, M.T.M.S. Gomes Jul 2007

Milk Protein Fouling In A Tubular Heat Exchanger: Effect Of Milk Temperature And Reynolds Number, D.H.G. Pelegrine, K.F. Oliveira, M.T.M.S. Gomes

Heat Exchanger Fouling and Cleaning VII

In the present work, β-lactoglobulin fouling phenomenon was studied, when milk flowed in a tubular heat exchanger, where hot water was used to raise milk temperature. Experiments have been carried out to determine the effect of Reynolds number and fluid temperature in whey protein fouling, in a tubular heat exchanger and the results showed that fouling increases as the fluid temperature increases. In addition, as the Reynolds number increases, the total amount of fouling (obtained by integrating the whole amount of deposit down the tube dividing by the total area) decreased.

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The Thermo-Hydrodynamics Of A Concentric Ohmic Heater For Processing Dairy Fluids, H.J. Tham, X.D. Chen, B. Young, B. Bansal, L. Zhang, G. Duffy Jul 2007

The Thermo-Hydrodynamics Of A Concentric Ohmic Heater For Processing Dairy Fluids, H.J. Tham, X.D. Chen, B. Young, B. Bansal, L. Zhang, G. Duffy

Heat Exchanger Fouling and Cleaning VII

The thermo-hydraulic performance of a 300W concentric annular ohmic heater was investigated. To minimize possible electrochemical reactions and corrosion, a higher frequency was applied and factors of field strength and frequency were studied. 2D computer simulation solving momentum, thermal and electrical energy was performed using the FlexPDE software. A good agreement between experimental and analytical analysis of static heating was obtained. There were significant differences between calculated and measured wall temperature near the entrance. The calculated outlet temperature was however in reasonable agreement with the experiment value.

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Influence Of Different Surface Materials On Nucleation And Crystal Growth In Heat Exchangers, T. Geddert, S. Kipp, W. Augustin, S. Scholl Jul 2007

Influence Of Different Surface Materials On Nucleation And Crystal Growth In Heat Exchangers, T. Geddert, S. Kipp, W. Augustin, S. Scholl

Heat Exchanger Fouling and Cleaning VII

The influence of different materials on the fouling tendency in saline calcium sulfate solution was investigated. The effects of the untreated material on the crystallization process have been studied experimentally in the micro- and macroscopic scale. The crystallization in the induction period was visualized with SEM and AFM to locate preferred nucleation spots and to visualize the crystal growth. The different materials are showing different crystal growth behavior (number and size of the crystals). These results are corresponding with the macroscopic fouling results with limited shear stress. Also different roughness values on stainless steel have been studied with respect to …

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Fouling In A Centritherm Evaporator With Whey Solutions, R. S. Jebson, H. Chen, O. H. Campanella Jul 2007

Fouling In A Centritherm Evaporator With Whey Solutions, R. S. Jebson, H. Chen, O. H. Campanella

Heat Exchanger Fouling and Cleaning VII

Fouling caused by sweet cheese whey and reconstituted whey powder solutions was studied in a Centritherm evaporator, the behaviour being estimated by measuring the change in the overall heat transfer coefficients with the time. It was found that there was no fouling detectable for the reconstituted whey powder solution. For sweet cheese whey, the fouling rate was linked strongly with the evaporating temperature and temperature difference. Visual observation showed that the deposit layer on the evaporator surface was very thin and soft, and like the type A milk deposit described by other investigators. A high velocity of liquid film delayed …

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Simulation Of Calcium Phosphate Deposition On Stainless Steel Surfaces: A New Approach Based On Cellular Automata, F. G. Martins, T. Campos, R. Rosmaninho, L. F. Melo Jul 2007

Simulation Of Calcium Phosphate Deposition On Stainless Steel Surfaces: A New Approach Based On Cellular Automata, F. G. Martins, T. Campos, R. Rosmaninho, L. F. Melo

Heat Exchanger Fouling and Cleaning VII

Fouling caused by calcium phosphate upon heating is basically a crystallization/precipitation process, which starts with the formation of stable clusters of ions or molecules in a process called nucleation that occurs either in the bulk liquid or at the surface. The cellular automata are useful tools to model complex systems of the universe. They could be considered as a good alternative to differential equations and have been used to model many physical/biological systems. In this preliminary work, a two dimensional space was considered where the cellular automata lattice was represented as a grid of squares, with each square representing a …

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Experimental Investigation Of Crystallization Fouling On Grooved Stainless Steel Surfaces During Convective Heat Transfer, A. Al-Janabi, M.R. Malayeri, H. Müller-Steinhagen Jul 2007

Experimental Investigation Of Crystallization Fouling On Grooved Stainless Steel Surfaces During Convective Heat Transfer, A. Al-Janabi, M.R. Malayeri, H. Müller-Steinhagen

Heat Exchanger Fouling and Cleaning VII

The beneficial aspects of enhanced or extended heat transfer surfaces may be off-set if operated under fouling conditions. In the present paper, preliminary experimental results for crystallization fouling of CaSO4 solutions onto surfaces with different structures are reported. Flat stainless steel plates (50 mm x 59 mm) with 'V' shaped grooves on the side of fluid flow were used as heat transfer surfaces. Experiments were carried out both under clean and fouling conditions to discern how the same surface structures perform under such circumstances. In addition, the impact of both, the direction of grooves with respect to fluid flow (crossed, …

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A Real Time Monitoring Model Of The Calcium Carbonate Fouling Induction Period Based On The Conductance Titration, S.R. Yang, S.X. Cao, L.J. Chen, Z.M. Xu, M.L. Yu, W.H. Sun, K.L. Zheng Jul 2007

A Real Time Monitoring Model Of The Calcium Carbonate Fouling Induction Period Based On The Conductance Titration, S.R. Yang, S.X. Cao, L.J. Chen, Z.M. Xu, M.L. Yu, W.H. Sun, K.L. Zheng

Heat Exchanger Fouling and Cleaning VII

A new method has been developed to monitor the calcium carbonate fouling induction period (CCFIP) in real time. Based on the conductance titration, this paper investigated the forming process of CCFIP by a staticdynamic combined simulation experiment unit. With the help of titration analysis (that is titrimetry), an accurate definition of CCFIP and the corresponding real time monitoring model were built up. The investigation results show that the proposed model applies not only to measure the CCFIP in real time, but also applies to an investigation of the influence of various factors on the CCFIP.

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Fouling Mitigation With Synthetic Fibres In A Caso4 Supersaturated Solution, M. Rost, G. G. Duffy Jul 2007

Fouling Mitigation With Synthetic Fibres In A Caso4 Supersaturated Solution, M. Rost, G. G. Duffy

Heat Exchanger Fouling and Cleaning VII

Wood pulp fibre suspensions and model synthetic fibre suspensions have been shown previously to mitigate effectively calcium sulphate fouling in heat exchangers. Fibre flexibility was found to be a decisive fibre property in fouling mitigation. Adding fibres to a fouling fluid is environmentally benign and can be applied during operation without shutting down the heat exchanger. Because polymer fibres are more robust in a hostile environment, further work was initiated with two types of rayon fibre and one acrylic fibre of the same fibre length. Experiments were performed at both constant and varying fibre volume concentrations. The more flexible rayon …

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Extending The Induction Period Of Crystallization Fouling Through Surface Coating, T. Geddert, I. Bialuch, W. Augustin, S. Scholl Jul 2007

Extending The Induction Period Of Crystallization Fouling Through Surface Coating, T. Geddert, I. Bialuch, W. Augustin, S. Scholl

Heat Exchanger Fouling and Cleaning VII

To minimize the negative effects of scale formation in heat exchangers, new anti-fouling strategies are focusing on the modification of heat transfer surfaces. These modifications should lead to tailored made surfaces for different technical applications. Aim of this surface modification is the extension of the induction period to minimize the negative effects of fouling and maximize the endurance of the heat exchanger. To achieve such, different surface coatings on stainless steel were investigated in respect of fouling tendency. The effect of flow velocity respectively Reynolds number on the induction time of CaSO4 crystallization fouling were tested in different test units. …

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Interaction Of Whey Protein With Modified Stainless Steel Surfaces, S.S. Premathilaka, M.M. Hyland, X.D. Chen, L.R. Watkins, B. Bansal Jul 2007

Interaction Of Whey Protein With Modified Stainless Steel Surfaces, S.S. Premathilaka, M.M. Hyland, X.D. Chen, L.R. Watkins, B. Bansal

Heat Exchanger Fouling and Cleaning VII

Modified stainless steel surfaces were fouled with whey protein solutions to study the deposition mechanisms and the effects of surface modification. Stainless steel samples were coated with diamond-like carbon (DLC) and titanium nitride (TiN). These surfaces are expected to present different surface chemistries to stainless steel in terms of their functional groups and hydrophobic or hydrophilic nature. Thus, it is expected that foulant-surface interactions will differ for the various fouled surfaces. The substrates were exposed to a flowing whey protein solution in a fouling rig designed to achieve laminar flow. X-ray Photoelectron Spectroscopy (XPS) was used to study the initial …

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Surface Treatment For The Mitigation Of Whey Protein Fouling, W. Augustin, T. Geddert, S. Scholl Jul 2007

Surface Treatment For The Mitigation Of Whey Protein Fouling, W. Augustin, T. Geddert, S. Scholl

Heat Exchanger Fouling and Cleaning VII

Heat transfer fouling experiments were carried out in a temperature controlled stirred vessel using aqueous solutions of whey protein concentrate in the concentration range of 3 to 3.5 wt-% at a bulk temperature of 50 °C and pH of 6. Heat transfer data were obtained from thermocouples embedded in an immersed electrical heating rod with various metal plates attached with-and-without surface treatments. Measurements included solution temperature, heating element surface temperature, and heat duty. Results are presented as fouling resistance versus time for aluminum, copper, stainless steel, electro-polished stainless steel, and surfaces coated with DLC and doped with Si , SiO, …

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Experiments And Modelling Of Calcium Sulphate Precipitation Under Sensible Heating Conditions: Initial Fouling And Bulk Precipitation Rate Studies, F. Fahiminia, A. P. Watkinson, N. Epstein Jul 2007

Experiments And Modelling Of Calcium Sulphate Precipitation Under Sensible Heating Conditions: Initial Fouling And Bulk Precipitation Rate Studies, F. Fahiminia, A. P. Watkinson, N. Epstein

Heat Exchanger Fouling and Cleaning VII

Crystallization of calcium sulphate, an inverse solubility salt, on a heated surface under sensible heating conditions has been studied. A temperature measurement technique was employed to detect initial fouling rates. Fouling experiments were carried out to determine how process variables such as surface temperature and velocity affect the initial fouling rates of calcium sulphate scaling. Experimental results show that, at a given surface temperature, there exists a maximum initial fouling rate for a range of fluid velocities. Also, this maximum rate and the fluid velocity at which it occurs both increase as the surface temperature increases. These observations are all …

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Flow Cell Studies On Fouling Caused By Protein -Calcium Phosphate Deposition In Turbulent Flow, R. Rosmaninho, G. Rizzo, H. Muller-Steinhagen, L. F. Melo Jul 2007

Flow Cell Studies On Fouling Caused By Protein -Calcium Phosphate Deposition In Turbulent Flow, R. Rosmaninho, G. Rizzo, H. Muller-Steinhagen, L. F. Melo

Heat Exchanger Fouling and Cleaning VII

A comparative study of the calcium phosphate fouling process, with and without proteins, was carried out using both standard 316 2R stainless steel and 2R surfaces modified by TiN magnetron sputtering. Fouling behavior was assessed in a heat transfer flow cell operating in the turbulent flow regime. The fouling curves resulting from calcium phosphate deposition in the absence of proteins were substantially different from the ones obtained when protein was present. In this last case, two different fouling periods could be observed. The surface energy of the modified materials was found to affect the deposition parameters (rate of deposition and …

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Investigation Of Fouling Process For Convective Heat Transfer In An Annular Duct, Y.C. Chen, Z.H. Quan, C.F. Ma Jul 2007

Investigation Of Fouling Process For Convective Heat Transfer In An Annular Duct, Y.C. Chen, Z.H. Quan, C.F. Ma

Heat Exchanger Fouling and Cleaning VII

Experimental and theoretical study is summarized of fouling process on heat transfer surface. An automatic monitoring system was set up to determine impact of fouling. Experiments were performed with artificial hard water as a working fluid at different conditions. Some important parameters including water temperature, wall temperature, flow velocity, water hardness and alkalinity were testified to make sure their influences on the fouling process on heat transfer surfaces. The ranges of water temperature, wall temperature, flow velocity and water hardness are between 20～50℃, 50～75℃, 0.5～2.0m/s, 200 ～ 1000mg/L (as CaCO3), respectively. All the experimental data were recorded continuously and the …

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Fouling Mechanisms By Ab Initio Calculations Condensation Reactions On The Rutile (101) Surface And Adsorption Of Ions On The Cr2o3 Surfaces, E. Puhakka, M. Riihimäki, R.L. Keiski Jul 2007

Fouling Mechanisms By Ab Initio Calculations Condensation Reactions On The Rutile (101) Surface And Adsorption Of Ions On The Cr2o3 Surfaces, E. Puhakka, M. Riihimäki, R.L. Keiski

Heat Exchanger Fouling and Cleaning VII

Molecular modelling approach was utilized to describe detailed fouling mechanism caused by crystallization. The interest was on the heat transfer surfaces, which were manufactured from titanium and stainless steel. With ab initio calculations, the role of the surface oxide layer structure of titanium and stainless steel on fouling was investigated. The surface structure of titanium and stainless steel were assumed to consist of rutile (TiO2) and dichromium trioxide (Cr2O3), respectively. It was found that the inorganic fouling depends strongly on the oxide layer structure and the existence of hydroxyl groups on the surface. Based on the results, two mechanistically different …

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Modelling Of Particulate Fouling On Heat Exchanger Surfaces: Influence Of Bubbles On Iron Oxide Deposition., D.H. Lister, F.C. Cussac Jul 2007

Modelling Of Particulate Fouling On Heat Exchanger Surfaces: Influence Of Bubbles On Iron Oxide Deposition., D.H. Lister, F.C. Cussac

Heat Exchanger Fouling and Cleaning VII

Studies of iron oxide deposition on Alloy-800 heatexchanger tubes have been part of a continuing research program at the University of New Brunswick; the present work formulates mechanisms for the effect of bubbles on deposition in water under boiling conditions. To supplement results from earlier deposition experiments in a fouling loop at UNB, measurements of bubble frequency and departure diameter as a function of heat flux were performed. High-speed movies of bubbling air/water systems indicated that a pumping action moved particles from adjacent areas at the surface to bubble nucleation sites. To explain the observations, the model considers deposition and …

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Simultaneous Consideration Of Flow And Thermal Effects Of Fouling In Crude Oil Preheat Trains, G.T. Polley, A. Morales Fuentes, D.I. Wilson Jul 2007

Simultaneous Consideration Of Flow And Thermal Effects Of Fouling In Crude Oil Preheat Trains, G.T. Polley, A. Morales Fuentes, D.I. Wilson

Heat Exchanger Fouling and Cleaning VII

Given models linking flow resistance and fouling resistance it becomes possible to simulate the effects of fouling on the hydraulic performance of a refinery pre-heat train. Such a simulation has been used here to identify when plant throughput will be limited by pressure drop; how throughput can be improved through the cleaning of individual exchangers and groups of exchangers; and how much production can be maintained when individual exchangers are taken off-line. Determination of better operating strategy requires a simulation of both hydraulic and thermal performance. In this paper we implement a pragmatic linked model and consider the results from …

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Optimization Of Flow Direction To Minimize Particulate Fouling Of Heat Exchangers, M.S. Abd-Elhady, C.C.M. Rindt, A.A. Van Steenhoven Jul 2007

Optimization Of Flow Direction To Minimize Particulate Fouling Of Heat Exchangers, M.S. Abd-Elhady, C.C.M. Rindt, A.A. Van Steenhoven

Heat Exchanger Fouling and Cleaning VII

The influence of flow direction with respect to gravity on particulate fouling of heat exchangers is investigated experimentally to determine the optimal flow direction to minimize fouling. Four orientations of flow have been investigated, horizontal flow, upward flow, downward flow and a flow under an angle of 45°. It is observed that fouling starts at the point of stagnation irrespective of the flow direction, and also at the top of the heat exchanger tubes. Particulate fouling grows from these two points till they meet and the fouling layer covers the whole surface of the heat exchanger tube. Fouling at the …

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Incorporation Of A Consideration Of Fouling Into The Design Of Vertical Thermo-Siphon Re-Boilers, G.T. Polley, S.J. Pugh Jul 2007

Incorporation Of A Consideration Of Fouling Into The Design Of Vertical Thermo-Siphon Re-Boilers, G.T. Polley, S.J. Pugh

Heat Exchanger Fouling and Cleaning VII

Two causes of under-performance within the tubes of vertical thermo-siphon re-boilers (VTR’s) are considered: premature dry-out within the unit and chemical reaction fouling at the tube wall. In many cases dryout is itself a cause of fouling. Both of these causes depend on re-boiler geometry. Some geometry performs satisfactorily. Other geometry performs poorly. There are two basic forms of flow boiling: nucleate flow boiling and convective flow boiling. In nucleate flow boiling part of the vaporisation results from the formation of bubbles of vapour on the heated surface. Unfortunately, a thin liquid film (the micro-layer) formed beneath these bubbles can …

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A Lagrangian Particle Cfd Post-Processor Dedicated To Particle Adhesion/Deposition, M. Losurdo, C. Bertrand, H. Spliethoff Jul 2007

A Lagrangian Particle Cfd Post-Processor Dedicated To Particle Adhesion/Deposition, M. Losurdo, C. Bertrand, H. Spliethoff

Heat Exchanger Fouling and Cleaning VII

In the past few years the use of biomass in power plants has grown dramatically. As a result of this action fouling and slagging in co-firing biomass facilities have turned out to play a critical role in the efficiency of such facilities. Efficient and effective methods are therefore needed to control fouling to an acceptable level and to prevent economic losses due to reduced furnace thermal efficiency, increased maintenance or even unscheduled outages. Numerical prediction of the impact of deposit properties has proved itself to be a successful strategy to both evaluate changes in the facility performance and to investigate …

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A Survey Of Alfa Laval’S Experience Of Fouling Prevention In Plate Heat Exchanger Systems, A. Tornqvist Jul 2007

A Survey Of Alfa Laval’S Experience Of Fouling Prevention In Plate Heat Exchanger Systems, A. Tornqvist

Heat Exchanger Fouling and Cleaning VII

This paper will present some aspects on and experiences of fouled plate heat exchangers in industrial applications as well as the present status on a new tool to monitor heat exchanger performance and to predict future cleaning procedures.

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Computation And Evaluation Of Wall Shear Stress Distribution At The Lower Surface Of A Radial Flow Cell, J. G. Detry, B. B. B. Jensen, C. Deroanne, M. Sindic Jul 2007

Computation And Evaluation Of Wall Shear Stress Distribution At The Lower Surface Of A Radial Flow Cell, J. G. Detry, B. B. B. Jensen, C. Deroanne, M. Sindic

Heat Exchanger Fouling and Cleaning VII

In the present work, the flow in the radial-flow cell was analyzed for an aspect ratio of 1 with inlet pipe Reynolds numbers of 950, 2 000 and 4 100. Two models were applied to compute the wall shear stress distribution at the lower surface, at any distance from the center. Stainless steel and polystyrene surfaces were soiled with oil and starch and the detachment of these soils was assessed by measuring the detachment radius in a radial-flow cell. The experimental radii were introduced in the models and converted into wall shear stress. Comparisons of the various sets of data …

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Effect Of Thermal Contact Resistance On The Heat Transfer In Plate Finned Tube Heat Exchangers, D. Taler Jul 2007

Effect Of Thermal Contact Resistance On The Heat Transfer In Plate Finned Tube Heat Exchangers, D. Taler

Heat Exchanger Fouling and Cleaning VII

Plate fin-and-tube heat exchangers are made by inserting oval tubes through sheet metal strips with stamped holes and then expanding the tubes slightly to cause pressure at the tube-to-strip contacts. The gap between the fin base and the outer tube surface may be filled with air or corrosion products causing a decline in the ability of plate fins to transfer heat. The contact resistance must be accounted for in the design and performance calculations of heat exchangers. In this paper, the thermal contact resistance of the fin-to-tube attachment is estimated from the condition that the dimensionless correlations for the Colburn …

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