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Full-Text Articles in Operations Research, Systems Engineering and Industrial Engineering

A Comparison Of The Operating Characteristics Of Two Cooling Water Systems Using Chlorine And Chlorine Dioxide Biocides, T. R. Bott, I.E. C. Mott May 2003

A Comparison Of The Operating Characteristics Of Two Cooling Water Systems Using Chlorine And Chlorine Dioxide Biocides, T. R. Bott, I.E. C. Mott

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

Tests using side streams from an industrial cooling water system have been made to compare the corrosion rates associated with the use of chlorine and chlorine dioxide biocides. Two streams were employed, a "once through" and a recirculating system employing a cooling tower. The water used in the plant originated from a canal. The results of the tests revealed differences in characteristics between the circuits, depending on the biocide used and the operating conditions. The data obtained demonstrated a higher corrosion rate of 1.5 mpy with chlorine compared to 1.0 mpy using chlorine dioxide.


Large-Scale Plasma Polymer Coating On Heat Exchanger Fins For Improving The Wettability, Ki-Hwan Kim, Dae-Hwan Yeu, Samchul Ha, Seok-Keun Koh May 2003

Large-Scale Plasma Polymer Coating On Heat Exchanger Fins For Improving The Wettability, Ki-Hwan Kim, Dae-Hwan Yeu, Samchul Ha, Seok-Keun Koh

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

This research presents the results of the recently developed large-scale hydrophilic polymer coating by plasma polymerization, optimum plasma zone (OPZ) process. The excellent hydrophilicity of heat exchanger fin surface could give good effects to efficient drainage of condensate water as well as heat transfer performance. The hydrophilicity of layer treated by large-scale OPZ system is excellent irrespective of line speed from 0.6 m/min to 2.4 m/min. The good lateral uniformity of the hydrophilicity could be acquired in large scale OPZ treatment. The application of OPZ technique to the heat exchanger could enhance the efficiency of heat ...


Fouling And Cleaning Of Modified Stainless Steel Plate Heat Exchangers Processing Milk Products, M. Beuf, G. Rizzo, J. C. Leuliet, H. Müller-Steinhagen, S. Yiantsios, A. Karabelas, T. Benezech May 2003

Fouling And Cleaning Of Modified Stainless Steel Plate Heat Exchangers Processing Milk Products, M. Beuf, G. Rizzo, J. C. Leuliet, H. Müller-Steinhagen, S. Yiantsios, A. Karabelas, T. Benezech

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

Fouling of heat exchangers in dairy industries is still quite a severe problem both technically and economically. Altering the surface properties of the heating surfaces would be a way of solving this issue.

Modified steel surfaces were tested in an Alfa Laval V2 plate heat exchanger throughout dairy product sterilization. The behavior was analyzed for 8 different surface treatments, such as coatings (Diamond Like Carbon [DLC], Silica, SiOX, Ni-P-PTFE, Excalibur®, Xylan®) and ion implantation (SiF+, MoS2).

All fouling and cleaning experiments were carried out in standard and well-controlled operating conditions. After fouling, no significant difference could be seen ...


Permanent Hydrophilic Surface Formation By Ion Assisted Reaction, Ki-Hwan Kim, Jun Sik Cho, Sung Han, Young Whoan Beag, Byung Ha Kang, Samchul Ha, Seok-Keun Koh May 2003

Permanent Hydrophilic Surface Formation By Ion Assisted Reaction, Ki-Hwan Kim, Jun Sik Cho, Sung Han, Young Whoan Beag, Byung Ha Kang, Samchul Ha, Seok-Keun Koh

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

Since totally wettable hydrophilic polymer surfaces from hydrophobic polymers (PMMA, PTFE, PET and PC) have been demonstrated for the first time at Materials Research Society meeting, 1995 Fall meeting, Boston, the application of ion assisted reaction (IAR), in which energetic ions (0.5~1.5 keV) are irradiated on materials with blowing reactive gases near the irradiating surfaces, has been extended to various polymer, ceramic and metal for creating permanent hydrophilic surfaces. The surface energy was measured by Youngs equation and the highest energy, Es, of 60~70 mN/m, which is similar to surface energy of water (E ...


Study Of The Influence Of Bulk Properties And Surface Tension On The Deposition Process Of Calcium Phosphate On Modified Stainless Steel, R. Rosmaninho, G. Rizzo, H. Müller-Steinhagen, L. F. Melo May 2003

Study Of The Influence Of Bulk Properties And Surface Tension On The Deposition Process Of Calcium Phosphate On Modified Stainless Steel, R. Rosmaninho, G. Rizzo, H. Müller-Steinhagen, L. F. Melo

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

In order to reduce the fouling caused by milk during heat treatment, it is important to know more about the deposition process of calcium phosphate, one of the main components of milk fouling, on stainless steel surfaces. The fouling behaviour of calcium phosphate is controlled by several factors related to both the fouling solution properties and the surface characteristics. The present work is focused on the influence of two of these factors: 1) the size and size distribution of the calcium phosphate aggregates formed in solution upon heating and 2) the surface tension values of the deposition surface. It was ...


Numerical Simulation Of The Fouling On Structured Heat Transfer Surfaces (Fouling), Fahmi Brahim, Wolfgang Augustin, Matthias Bohnet May 2003

Numerical Simulation Of The Fouling On Structured Heat Transfer Surfaces (Fouling), Fahmi Brahim, Wolfgang Augustin, Matthias Bohnet

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

The objective of this work is to make a contribution to a good and fast prediction of the crystal growth on flat and structured heat transfer surfaces. For the numerical simulation the CFD code Fluent is used. The simulation enables an unsteady calculation of the fouling process and a realistic description of the temporal modification of the flow and temperature fields due to the continuous crystal growth. The numerical simulation of the crystal growth is based on models for the calculation of the deposition (Krause, 1993) and removal (Bohnet, 1990) mass rates. Based on experimental results of Hirsch (Bohnet et ...


Removal Of Particles From A Powdery Fouled Surface Due To Impaction, M. S. Abd-Elhady, C. C.M. Rindt, J. G. Wijers, A. A. Van Steenhoven May 2003

Removal Of Particles From A Powdery Fouled Surface Due To Impaction, M. S. Abd-Elhady, C. C.M. Rindt, J. G. Wijers, A. A. Van Steenhoven

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

Particulate fouling is defined as the unwanted deposition of particles on heat exchange surfaces. The fouling layer reduces the heat transfer rate and leads to inefficient operation. The net fouling rate is the result of the difference between the deposition rate and the removal rate of particles. One of the mechanisms that contribute to the removal of particles from powdery fouled surfaces is the collision of an incident particle with the fouled surface. In the present study, removal of particles from powdery fouled surfaces due to an incident particle impact is studied numerically and experimentally. A numerical model is developed ...


Heat Treatment Improvement Of Dairy Products Via Ohmic Heating Processes : Thermal And Hyrodynamic Effect On Fouling, M. A. Ayadi, L. Bouvier, F. Chopard, M. Berthou, J. C. Leuliet May 2003

Heat Treatment Improvement Of Dairy Products Via Ohmic Heating Processes : Thermal And Hyrodynamic Effect On Fouling, M. A. Ayadi, L. Bouvier, F. Chopard, M. Berthou, J. C. Leuliet

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

Fouling and consequently cleaning of heat exchangers in the dairy industry are nowadays a significant issue still not solved for the processing of quite a large variety of products. Ohmic heating processes for food products a priori are well known to minimize the fouling phenomenon due to a totally different way of heating food by admitting the current directly in the product. Such a technology could be a good alternative to counter both fouling and cleaning aspects when pasteurizing or sterilizing dairy desserts known to generate large amounts of soil on heated surfaces. The aim of this experimental study was ...


Analysis Of Fouling Data Based On Prior Knowledge, M. R. Malayeri , H. Müller-Steinhagen May 2003

Analysis Of Fouling Data Based On Prior Knowledge, M. R. Malayeri , H. Müller-Steinhagen

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

Conventional regression methods are generally unable to analyse extremely complicated processes involving a considerable number of independent variables with poorly understood interaction. These methods use a defined equation for which the parameters of this equation have to be determined. It is however questionable whether any arbitrarily chosen equation is the best. This study aims to implement the powerful neural network architecture for a comprehensive data bank. The HTRI data bank contains a large and unique set of experimental data for cooling water fouling. Only a selection of the data bank is being used at the present time, due to the ...


Challenges In Cleaning: Recent Developments And Future Prospects, D. I. Wilson May 2003

Challenges In Cleaning: Recent Developments And Future Prospects, D. I. Wilson

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

There is considerable scope for optimisation of processes subject to fouling by effective management of cleaning. The cleaning cycle starts with the (often-complex) material generated during the fouling cycle. The nature of the deposit determines the most appropriate cleaning method, which can often be optimised significantly via knowledge of the key mechanisms involved in deposit removal. Links between deposit ageing and cleanability need to be established and quantified. There is a wide range of cleaning methods available, and attention is focused here on cleaning-in-place (CIP) techniques. Modern instrumentation allows cleaning (and deposit materials behaviour) to be probed to greater degree ...


A Mathematical Model Of The Removal Of Milk Protein Deposit, Hong Xin, Xiao Dong Chen, Necati Özkan May 2003

A Mathematical Model Of The Removal Of Milk Protein Deposit, Hong Xin, Xiao Dong Chen, Necati Özkan

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

Based on a polymer dissolution controlled chemical cleaning mechanism, a mathematical model has been developed to describe the different stages of the removal of milk protein fouling from a hard surface. Various processes, such as reptation, disengagement, mass transfer through the boundary layer and surface area changes during the decay cleaning stage have been taken into account in the modelling process. The successful prediction of the cleaning process under various conditions indicates that the model has proposed a rational mechanism accounting for the removal of milk protein fouling.


The Balance Between In The Cleaning Of Milk Fouling Deposits, G. K. Christian , P. J. Fryer May 2003

The Balance Between In The Cleaning Of Milk Fouling Deposits, G. K. Christian , P. J. Fryer

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

Deposits formed on the surface of heat treatment equipment in the dairy industry compromise product quality and process efficiency. Frequent cleaning is needed to ensure consumer safety and optimal process operation. Cleaning solutions generally have a high environmental impact; the need is to minimize their use. We have studied the physics and chemistry of cleaning at two length scales of measurement: (i) the effect of cleaning chemical and water on deposits within a plate heat exchanger (PHE), and (ii) the effect of process variables on small fouled disks. The chemical nature of cleaning of dairy deposits is shown clearly by ...


Study Of Whey Protein Adsorption Under Turbulent Flow , Olga Santos, Tommy Nylander, Gerhard Rizzo , Hans Müller-Steinhagen, Christian Trägårdh, Marie Paulsson May 2003

Study Of Whey Protein Adsorption Under Turbulent Flow , Olga Santos, Tommy Nylander, Gerhard Rizzo , Hans Müller-Steinhagen, Christian Trägårdh, Marie Paulsson

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

Reducing fouling in heat exchangers during treatment of milk products is one of the great challenges in the dairy industry. One approach to mitigate fouling is to alter the surface characteristics of the heat exchangers making them less prone to protein adsorption. On this background the European project MODSTEEL was established to study the use of new modified stainless steel surfaces to control fouling of milk components. This part of the project focuses on the adsorption of b-lactoglobulin (b-Lg) from a whey protein solution on unmodified and modified 316 2R stainless steel surfaces by in situ ellipsometry under well-defined flow ...


Direct Measurement Of The Forces Required To Disrupt And Remove Fouling Deposits, W. Liu, Z. Zhang, G. K. Christian, P. J. Fryer May 2003

Direct Measurement Of The Forces Required To Disrupt And Remove Fouling Deposits, W. Liu, Z. Zhang, G. K. Christian, P. J. Fryer

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

In cleaning, the force required to disrupt the deposit and remove it from the surface tends to be inferred from flow data, rather than being known directly. A novel micromanipulation technique has been developed to measure directly the adhesive strength of food fouling deposits on a stainless steel surface. A T-shaped stainless steel probe pulls fouling deposits away from the surface to which they are attached. The apparent adhesive strength between the fouling deposits and the substrate can be measured as the work required to remove the deposits per unit area from the substrate. Tomato pastes and whey proteins have ...


Fouling Of Some Canadian Crude Oils, M. Srinivasan , A. P. Watkinson May 2003

Fouling Of Some Canadian Crude Oils, M. Srinivasan , A. P. Watkinson

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

A thermal fouling study was undertaken using three sour Canadian crude oils. Experiments were carried out in a re-circulation fouling loop, equipped with an annular (HTRI) electrically heated probe. Fluids at pressures of about 1000-1340 kPa under a nitrogen atmosphere were re-circulated at a velocity of 0.75 m/s for periods of 48 hours, and the decline in heat transfer coefficient followed under conditions of constant heat flux. Bulk temperatures were varied over the range 200-285°C, and initial surface temperatures from 300 to 380°C. Heat fluxes were in the range of 265-485 kW/m2.


Preheat Train Crude Distillation Fouling Propensity Evaluation By The Ebert And Panchal Model, M. Bories , T. Patureaux May 2003

Preheat Train Crude Distillation Fouling Propensity Evaluation By The Ebert And Panchal Model, M. Bories , T. Patureaux

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

The Ebert and Panchal fouling model was used to assess the fouling tendency of the exchangers of an industrial crude distillation unit (CDU) preheat train. The ranking obtained through a monitoring and processing of the performances of the different exchangers matched quite well the predictions of the Ebert and Panchal fouling model. In the meantime, a first mitigation solution consisted in periodically cleaning heat exchangers and installing TURBOTALTM tube inserts. Through the fouling monitoring of the equipped exchangers, the beneficial action of the TURBOTALTM inserts is also made quite clear.


Retrofitting Crude Oil Refinery Heat Exchanger Networks To Minimise Fouling While Maximising Heat Recovery, B. L. Yeap, D. I. Wilson, G. T. Polley, S. J. Pugh May 2003

Retrofitting Crude Oil Refinery Heat Exchanger Networks To Minimise Fouling While Maximising Heat Recovery, B. L. Yeap, D. I. Wilson, G. T. Polley, S. J. Pugh

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

The use of fouling factors in heat exchanger design and the lack of appreciation of fouling in traditional pinch approach has often resulted badly designed crude preheat networks that are expensive to maintain. The development of thermal and pressure drop models for crude oil fouling has allowed its effects to be quantified, so that techno-economic analyses can be performed and various design options compared. Application of these fouling models is carried out on two levels: on the assessment of adding extra area to individual exchangers, and the design of a complete network using the Modified Temperature Field Plot. Application to ...


Chemical Cleaning Of Oil Refinery Heat Exchangers -- The Need For A Joint Effort, Himanshu M. Joshi, Glen Brons May 2003

Chemical Cleaning Of Oil Refinery Heat Exchangers -- The Need For A Joint Effort, Himanshu M. Joshi, Glen Brons

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

One component of the high cost of fouling to oil refineries is the maintenance money spent to clean fouled heat exchangers and the associated lost production while the exchanger is out of service. This presentation will highlight some specific fouling situations in oil refineries which can benefit from chemical cleaning. Cooperative efforts are needed between refinery operators, researchers, and chemical suppliers to develop the proper solvents and to find the optimum procedures to use them for cleaning.


Analysis And Steps To Mitigate Heat Exchanger Fouling In An Aromatics Plant, Shinji Isogai , Mitsutaka Nakamura May 2003

Analysis And Steps To Mitigate Heat Exchanger Fouling In An Aromatics Plant, Shinji Isogai , Mitsutaka Nakamura

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

A heat exchanger, upstream a distillation tower for the separation of BTX (benzene, toluene, xylene) from crude benzene in an aromatics plant, experiences heavy fouling. The fouling mechanism and countermeasures to mitigate or eliminate it, were investigated. An Alcor Hot Liquid Process Simulator (HLPS)was used for the fouling rate measurement. The main mechanism is a combination of precipitation fouling and chemical reaction fouling. Effects, such as temperature, vapor ratio (vapor mole fraction of the fluid), heater materials, surface roughness and the addition of some different types of chemicals were studied. From the experiments, some countermeasures for this fouling were ...


Fouling Characteristics Of A Light Australian Crude Oil, Zaid S. Saleh, R. Sheikholeslami, A. P. Watkinson May 2003

Fouling Characteristics Of A Light Australian Crude Oil, Zaid S. Saleh, R. Sheikholeslami, A. P. Watkinson

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

Australian crude oils, which generally contain little asphaltenes, nevertheless give rise to fouling in refinery pre-heat trains. In this research, fouling of a series of such crude oils and their blends is being assessed. The present work focuses on thermal fouling resulting from heating Gippsland crude oil at moderate temperatures. The oil is maintained under nitrogen at a pressure of 379 kPa, and re-circulated at bulk temperatures of 80-120°C through an electrically heated annular probe at velocities in the range 0.25 to 0.65 m/s with surface temperatures from 180-260°C. Experiments are run for periods up ...


Comparison Of Crude Oil Fouling Using Two Different Probes, A. P. Watkinson May 2003

Comparison Of Crude Oil Fouling Using Two Different Probes, A. P. Watkinson

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

A variety of different fouling rigs, each with its own advantages and disadvantages is available to assess crude oil fouling. In this research, fouling of three crude oils are compared, using two electrically heated annular probes with strikingly different modes of operation. The Hot Liquid Process Simulator (HLPS) was operated in single-pass mode, under creeping flow conditions for time durations of a few hours at constant surface temperature. The Portable Fouling Research Unit (PFRU) was operated at velocities a factor of 250 higher, and followed the fouling process over two or more days at constant heat flux, using re-circulation of ...


Table Of Contents, The Editors May 2003

Table Of Contents, The Editors

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

No abstract provided.


Preface, The Editors May 2003

Preface, The Editors

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

No abstract provided.


Fouling During The Use Of Seawater As Coolant - The Development Of A ‘User Guide’, S. Pugh, G.F. Hewitt, H. Müller-Steinhagen May 2003

Fouling During The Use Of Seawater As Coolant - The Development Of A ‘User Guide’, S. Pugh, G.F. Hewitt, H. Müller-Steinhagen

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

ESDU International of London, UK has recently published a ‘User Guide’ on fouling in heat exchange systems using seawater as the coolant. Developed over a period of eighteen months in close collaboration with a team of oil refiners, heat transfer equipment and services suppliers and universities, with valuable input from the power industry, the User Guide is a practical guide to the current state of knowledge relating to fouling in cooling systems using seawater. Its objective is to provide the designer and the operator of both onshore and offshore equipment with a practical source of guidance on the occurrence, the ...


Physical Water Treatment For The Mitigation Of Mineral Fouling In Cooling-Tower Water Applications, Young I. Cho, Sunghyuk Lee, Wontae Kim, Sangho Suh May 2003

Physical Water Treatment For The Mitigation Of Mineral Fouling In Cooling-Tower Water Applications, Young I. Cho, Sunghyuk Lee, Wontae Kim, Sangho Suh

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

The physical water treatment (PWT) device is defined as a non-chemical method of water treatment utilized for the purpose of scale prevention or mitigation. Three different PWT devices, including permanent magnets, solenoid coil device, and high-voltage electrode, were used under various operating conditions. The present study proposed a bulk precipitation as the mechanism of the PWT and conducted a number of experimental tests to evaluate the performance of the PWT. The results of fouling resistances obtained in a heat transfer test section clearly demonstrated the benefit of the PWT when the PWT device was configured at an optimum condition. The ...


Investigation Of Initial Fouling Rates Of Calcium Sulfate Solutions Under Non-Boiling Conditions (Work-In-Progress), Feridoun Fahiminia, A. Paul Watkinson , Norman Epstein May 2003

Investigation Of Initial Fouling Rates Of Calcium Sulfate Solutions Under Non-Boiling Conditions (Work-In-Progress), Feridoun Fahiminia, A. Paul Watkinson , Norman Epstein

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

This study initiates an experimental investigation of how process variables such as temperature and velocity affect the initial precipitation fouling rate of the inverse solubility salt, calcium sulfate, under sensible heating conditions. The effect of fluid velocity and temperature on the delay time is also being measured.


Crystallisation Fouling Of Mixed Salts During Convective Heat Transfer And Sub-Cooled Flow Boiling Conditions, A. Helalizadeh, H. Müller-Steinhagen, M. Jamialahmadi May 2003

Crystallisation Fouling Of Mixed Salts During Convective Heat Transfer And Sub-Cooled Flow Boiling Conditions, A. Helalizadeh, H. Müller-Steinhagen, M. Jamialahmadi

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

The mechanisms of mixed salt crystallisation fouling on heat transfer surfaces have been investigated for convective and sub-cooled flow boiling heat transfer. Effects of various operating parameters such as solution composition and hydrodynamics of the system, on crystallisation fouling of mixtures of calcium sulphate and calcium carbonate have been studied experimentally. The results of the experiments were used to develop a mechanistic model for prediction of fouling resistances. Model predictions were compared with the measured experimental data when calcium sulphate and calcium carbonate form and deposit on the heat transfer surface, simultaneously. Deviations ranging from 6% to 25% were observed ...


Crystallization Fouling Of The Aqueous Two-Component System Caso4/Caco3, Volker Höfling, Wolfgang Augustin , Matthias Bohnet May 2003

Crystallization Fouling Of The Aqueous Two-Component System Caso4/Caco3, Volker Höfling, Wolfgang Augustin , Matthias Bohnet

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

Solutions, which cause fouling problems, consist mostly of more than one single component. Up to now only few studies concerning the fouling phenomena in such multicomponent systems exist. Therefore batch and continuous experiments with the aqueous two-component system CaSO4/CaCO3 were carried out, investigating especially the influence of pH-value on the fouling behaviour. As measure for the crystalline deposit the fouling resistance Rf was used.

The composition of the obtained fouling layers were analysed by x-ray diffraction and scanning electron microscopy (SEM). Further the strength of the crystalline deposits were determined in abrasion experiments. The measured abrasion ...


Deposition Of Na2Co3 In Supercritical Water Oxidation Systems And Its Mitigation, M. S. Khan, S. N. Rogak May 2003

Deposition Of Na2Co3 In Supercritical Water Oxidation Systems And Its Mitigation, M. S. Khan, S. N. Rogak

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

Supercritical water oxidation is a technique to destroy wet organic waste. The oxidation reaction takes place at high temperature and pressure. Organics are miscible at these conditions but inorganic salts are not soluble and present fouling problems. Examples of these salts are sodium sulfate and sodium carbonate.

Research is being done in the University of British Columbia to study the fouling behavior of Na2CO3 in the SCWO reactor. The working fluid is heated by passing alternating current through the reactor wall. Since the tube surface was hotter than the bulk fluid, the salt was expected to nucleate ...


Heat Exchanger Fouling In Phosphoric Acid Evaporators - Evaluation Of Field Data -, R. M. Behbahani, H. Müller-Steinhagen, M. Jamialahmadi May 2003

Heat Exchanger Fouling In Phosphoric Acid Evaporators - Evaluation Of Field Data -, R. M. Behbahani, H. Müller-Steinhagen, M. Jamialahmadi

Heat Exchanger Fouling and Cleaning: Fundamentals and Applications

Multistage evaporators are frequently used in phosphoric acid plants to increase the concentration of dilute phosphoric acid to 52-55 wt% P2O5. The concentrated phosphoric acid solution is supersaturated with respect to calcium sulfate. As a result, part of the calcium sulfate in the liquor deposits on the heat exchanger tube walls. Since the thermal conductivity of these scales is very low, thin deposits can create a significant resistance to heat transfer. Therefore, regular cleaning of heat exchangers is required, frequently at less than biweekly intervals. As the major costs in modern phosphoric acid plants are the cost ...