Publications
240 results found
Coletti F, Diaz Bejarano E, Macchietto S, 2018, Dynamic Data Analysis™ of large scale data to monitor fouling in heat exchanger networks, 2018 AIChE Spring Meeting and 14th Global Congress on Process Safety, Publisher: American Institute of Chemical Engineers
Data collected from heat exchangers networks in the field are typically used to monitor the thermal performance of the individual units. However, the information extracted from the data is limited in quantity and quality by the simplified models typically used in practice. Key decisions such as cleaning of heat exchangers rely on the calculation of derived quantities such as the fouling resistance which lumps together a number of factors contributing to fouling. This approach has been severely criticised in the past by various authors but it is still widely used in the industrial practice [1]. In this paper it is shown that a significantly larger amount of information and insights can be extracted from the same measurements by using rigorous models and a flexible framework. It is shown how this approach leads to a much deeper analysis of the status of the network which, in turn, helps with diagnosis and troubleshooting. An industrial case study is presented to illustrate the benefits.
Coletti F, Lozano Santamaria F, Diaz Bejarano E, et al., 2018, Optimization of refinery preheat trains: predictive maintenance and operations improvement, 2018 AIChE Spring Meeting and 14th Global Congress on Process Safety, Publisher: American Institution of Chemical Engineering
Deciding which heat exchanger to clean, when to clean and how to clean in refinery pre-heat trains is a challenging activity that typically relies on operator’s experience. In this paper, an algorithm that allow identifying the most economic cleaning schedule for a given refinery configuration and operating conditions is presented. The method relies on an advanced framework that incorporates rigorous heat exchanger models capable of predicting the fouling behaviour of the refinery as a function of configuration of the individual units and the network, process conditions and time. An industrial case study is presented to illustrate the benefits of the approach, showing that significant improvements over current practice can be obtained.
Diaz Bejarano E, Coletti F, Macchietto S, 2018, Improving crude oil fouling monitoring, prediction and mitigation strategies in refinery preheat trains, 2018 AIChE Spring Meeting and 14th Global Congress on Process Safety, Publisher: American Institute of Chemical Engineering
Traditional heat exchanger monitoring methodologies rely on fouling resistance calculations that neglect the effects of fouling on pressure drops, and are not able to predict future performance as a function of process conditions, heat exchangers geometry and network configurations. In this paper, an improved approach to monitoring of fouling in refinery pre-heat trains that rely on rigorous predictive models is summarised and illustrated with an industrial case study.
Diaz Bejarano E, Coletti F, Macchietto S, 2018, Identifying the causes of acute fouling in refinery preheat train, 2018 AIChE Spring Meeting and 14th Global Congress on Process Safety, Publisher: American Institute of Chemical Engineers
Crude oil fouling is typically treated in the literature as a phenomenon involving the deposition of organic material on the thermal surfaces of heat exchangers. Little attention is paid to the effects that inorganic species have on the thermal and hydraulic performance of the heat exchangers affected. When deposition of inorganic species occurs, it is often the cause of an upset in operations (e.g. issues with the desalter) that results in episodes of rapid (acute) fouling. In this paper, a method used to detect acute fouling episodes and identifying their causes is presented.
Behranvand E, Mozdianfard MR, Diaz-Bejarano E, et al., 2018, A comprehensive investigation of refinery preheaters foulant samples originated by heavy crude oil fractions as heating fluids, Fuel, Vol: 224, Pages: 529-536, ISSN: 0016-2361
A deep understanding of the mechanisms responsible for fouling from both crude oils and their fractions is paramount to ensure efficient energy recovery in heat exchangers of crude preheat trains. In this work, seven samples of fouling deposits, carefully collected from a number of refinery heat exchangers processing vacuum gas oil (VGO) and vacuum bottom (VB) streams in an atmospheric crude preheat train were investigated using a range of characterization techniques with the aim of identifying the underlying mechanisms that led to deposition. Characterization of the deposits included morphological and physical examination, fractionating solubility test, Scanning Electron Microscopy-Energy Dispersive X-ray, Combustion Analysis and X-ray Diffraction. In all samples examined, more than 75 wt% of the deposits were identified as inorganic, with about 50 wt% being FeS. At 270–300 °C, FeO(OH) was also identified to be deposited on the tube surfaces made in Cr steel alloy, where more fouling and less corrosion were evident compared to carbon steel (CS). These observations were found in agreement with recent laboratory studies aimed at identifying the role of temperature and tube material in petroleum corrosion. Furthermore, sulphur crystals were found in several VGO fouling samples. Based on the experimental results obtained, a mechanism was proposed to explain the corrosion fouling phenomenon, considered to be the underlying mechanism affecting the refinery. The mechanism involves naphthenic acid attack to the tubes’ metal surface, decomposition of iron naphthenate, disproportion of iron oxide and sulphidation reactions. The results highlighted the importance of studying deposits formed under industrial conditions, timescales and variation of the deposition process, evidenced by the deposit characteristics, along extensive heat exchanger networks.
Diaz-Bejarano E, Coletti F, Macchietto S, 2018, Identifying the causes of acute fouling in refinery preheat train, Pages: 106-109
Crude oil fouling is typically treated in the literature as a phenomenon involving the deposition of organic material on the thermal surfaces of heat exchangers. Little attention is paid to the effects that inorganic species have on the thermal and hydraulic performance of the heat exchangers affected. When deposition of inorganic species occurs, it is often the cause of an upset in operations (e.g. issues with the desalter) that results in episodes of rapid (acute) fouling. In this paper, a method used to detect acute fouling episodes and identifying their causes is presented.
Santamaria FL, Macchietto S, 2018, Optimal cleaning scheduling and control of heat exchanger networks: Problem formulation and solution strategy, Pages: 1-8
In crude oil processing heat exchanger fouling is a major problem because it reduces the thermal and hydraulic performance of the units which has a large effect in the energy efficiency and operational cost. Fouling mitigation alternatives are mandatory and two of the most common and effective are: flow distribution control in heat exchanger networks, and periodic cleanings. These two mitigation alternatives can be defined individually by solving two distinct optimization problems, an optimal control problem (NLP) for the optimal flow distribution, and an optimal scheduling problem (MINLP) for the cleaning scheduling. However, there are important interactions between these two mitigation strategies that are neglected when addressed independently, while solving the integrated scheduling and control problem has economic benefits, but it is highly challenging. Here we present a general, flexible and accurate formulation to model heat exchanger networks under fouling, and an efficient solution strategy to tackle the optimal control and optimal scheduling problems simultaneoulsy. The formulation is able to capture all the important interactions of the operation, and includes all variables for the various decisions. The integrated control and scheduling problem is reformulated as a MPCC (mathematical problem with complementarity constraints) and then solved using a NLP solver based on interior point methods. A case study of industrial significance is used to illustrate the advantages of the formulation, the efficiency of the solution, and the benefits of considering the control and scheduling optimization problems at the same decision level.
Santamaria FL, Macchietto S, 2018, Optimal cleaning scheduling and control of heat exchanger networks: An industrial case study, Pages: 50-57
Fouling in heat exchangers of refinery applications has a high impact on operations as it reduces the thermal and hydraulic performance of the units. Fouling mitigation is required to keep the operation closer to the optimal point of low energy consumption, high throughput, and high safety standards. Two fouling mitigation alternatives are commonly used in the operation of large networks: periodic cleanings and flow rate control. The first one can remove the deposit but requires units to be taken out of service, while the second one allows a continued operation, but it just reduces the deposition rate. These two strategies have strong interactions that define the performance of the preheat train. Here we analyze the simultaneous solution of the optimal cleaning scheduling and optimal flow distribution for an industrial case study of the hot end of the preheat train. The problem is formulated as a large scale nonlinear mathematical programming problem with binary variables, which is solved efficiently using complementarity constraints. The optimal simultaneous solution of both problems has an economic benefit over the actual operation of the preheat train (based on past data) of $ 3.2 M over an operation horizon of 4 years.
Coletti F, Diaz-Bejarano E, MacChietto S, 2018, Dynamic data analysis™ of large scale data to monitor fouling in heat exchanger networks, Pages: 88-91
Data collected from heat exchangers networks in the field are typically used to monitor the thermal performance of the individual units. However, the information extracted from the data is limited in quantity and quality by the simplified models typically used in practice. Key decisions such as cleaning of heat exchangers rely on the calculation of derived quantities such as the fouling resistance which lumps together a number of factors contributing to fouling. This approach has been severely criticised in the past by various authors but it is still widely used in the industrial practice [1]. In this paper it is shown that a significantly larger amount of information and insights can be extracted from the same measurements by using rigorous models and a flexible framework. It is shown how this approach leads to a much deeper analysis of the status of the network which, in turn, helps with diagnosis and troubleshooting. An industrial case study is presented to illustrate the benefits.
Macchietto S, Coletti F, Bejarano ED, 2018, Energy Recovery in Heat Exchanger Networks in a Dynamic, Big-data World: Design, Monitoring, Diagnosis and Operation, Computer Aided Chemical Engineering, Pages: 1147-1152
Heat exchanger networks (HENs) are often analysed with simplified models which are not sufficiently predictive in the presence of fouling, in particular for operations monitoring, diagnosis and support. A comprehensive approach is presented, with application to oil refining, that moves substantially beyond the usual simplifying assumptions and incorporates: i) far more detailed models of the physics involved ii) detailed dynamics for both slow and fast changes; iii) detailed reaction engineering models of the deposition of fouling deposits on thermal surfaces as well as deposits removal in chemical and mechanical cleanings; iv) the ability to easily generate multi-scale, detailed models of individual exchangers and whole networks; v) consideration of the complex thermal and hydraulic interactions between exchangers and effects on performance; vi) exploiting the abundant plant data available (historical and current) in conjunction with the more sophisticated models; vii) solution of all problems within an easy to use engineering software environment.
Santamaria FL, Macchietto S, 2018, Integration of Optimal Cleaning Scheduling and Flow Split Control for Crude Oil Fouling Mitigation in the Operation of Refinery Heat Exchanger Networks, Computer Aided Chemical Engineering, Pages: 1087-1092
Fouling in heat exchangers, a slow dynamic process, significantly reduces their thermal and hydraulic performance. For heat exchanger networks (HENs) in particular, mitigation alternatives are needed to restore a profitable and safe operation. Controlling the flow rate distribution in parallel branches of the network is one option, periodically cleaning selected heat exchangers another. These two strategies have been traditionally addressed separately or sequentially, but there is a strong interaction between them. We propose i) a general formulation to model heat exchanger networks under fouling, suitable for ii) the simultaneous optimal control and optimal cleaning scheduling. The resulting large scale dynamic optimization problem with binary variables (MINLP) is reformulated as a mathematical program with complementarity constraints (MPCC) which is solved efficiently for networks of industrially relevant size. The benefit of integrating the two decision layers is demonstrated in a case study for a crude oil preheat train, where the simultaneous solution of the two problems leads to a 25 % savings in operational cost.
Guan S, Macchietto S, 2018, A Novel Dynamic Model of Plate Heat Exchangers Subject to Fouling, Editors: Friedl, Klemes, Radl, Varbanov, Wallek, Publisher: ELSEVIER SCIENCE BV, Pages: 1679-1684
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- Citations: 6
Diaz Bejarano E, Behranvand E, Coletti F, et al., 2017, Organic and inorganic fouling in heat exchangers – industrial case study: analysis of fouling state, Applied Energy, Vol: 206, Pages: 1250-1266, ISSN: 0306-2619
A comprehensive model-based thermo-hydraulic methodology is used to investigate fouling behaviour in refinery heat exchangers where high concentration of inorganics in the deposits was reported. The method combines a data-driven analysis of plant measurements (including pressure drop) with a model-based analysis using advanced models of shell-and-tube heat exchangers undergoing fouling. A deposit model capable of tracking composition and deposition history was extended to include thermal-conductivity mixing models appropriate for various deposit structures. Substantial new and useful information can be extracted from the plant measurements in comparison to current practice: the thickness, the effective conductivity, and the radial conductivity and composition profiles of the deposits, reflecting the exchanger operation history. Episodes of rapid and acute fouling, and deposition of inorganic materials could be identified and quantified. A validation of the approach was carried out by (i) a comparison of averaged predicted and experimental inorganic weight fractions in a mixed deposit sample collected at the end of run, and (ii) an initial comparison of predicted radial inorganics profiles and experimental ones (obtained with SEM-EDX) in deposits from similar exchangers. Both steps yielded surprisingly good agreement. The study indicates that the method employed represents a new powerful, model-based analysis tool for monitoring, diagnosis and troubleshooting of fouling in heat exchangers.
Macchietto S, Coletti F, 2017, Engineering innovation by design: The uniheat project, 2017 AIChE Spring Meeting, Pages: 711-730
Diaz-Bejarano E, Coletti F, Macchietto S, 2017, Thermo-hydraulic analysis of refinery heat exchangers undergoing fouling, AIChE Journal, Vol: 63, Pages: 984-1001, ISSN: 0001-1541
A complete, systematic approach is presented for the analysis and characterization of fouling and cleaning in refinery heat exchangers. Bringing together advanced thermo-hydraulic dynamic models, some new formulations, and a method for dynamic analysis of plant data, it allows: extracting significant information from the data; evaluating the fouling state of the units based on thermal measurements and pressure drops, if available; identifying the range of deposit conductivity leading to realistic pressure drops, if pressure measurements are unavailable; estimating key fouling and ageing parameters; estimating the effectiveness of cleaning and surface conditions after a clean; and predicting thermal and hydraulic performance with good accuracy for other periods/exchangers operating in similar conditions. An industrial case study demonstrates the performance prediction in seamless simulations that include partial and total cleanings for over 1000 days operation. The risks of using thermal effects alone and the significant advantages of including pressure drop measurements are highlighted.
Macchietto S, Coletti F, 2017, Engineering innovation by design: The uniheat project, Pages: 238-257
Diaz-Bejarano E, Coletti F, Macchietto S, 2017, A novel way of monitoring heat exchanger performance: The dynamic TH-γ plot, Pages: 274-285
In many industrial situations, from milk processing to refining, heat exchanger performance changes over time due to deposition of material on exchange surfaces (fouling) leading to losses in duty (reduced thermal efficiency) and increased pressure drop (reduced hydraulic efficiency). Operating performance is usually measured by monitoring just thermal efficiency, typically using thermal efficiency measures such as fouling resistance, Rf, that are easy to calculate. The reasons of thermal inefficiency, however, can be quite varied, ranging from different deposition rates, deposition of materials with different thermal conductivity, coking of existing deposits, to removal of deposits by shear, often having opposite effects. On its own, simply monitoring fouling resistance can give quite misleading indications of performance, and of the underlying conditions of the exchanger. The dynamic TH-γ plot is an easy to understand, rich visualisation that combines information about both the thermal and hydraulic evolution of the performance of a heat exchanger. In its simplest form, it evidences the changes in duty and pressure drop relative to clean performance and permits tracking and assessing the approach to thermal (T) and hydraulic (H) limits. The addition of characteristic reference lines for deposits of constant thermal conductivity, the so called γ -lines, allows monitoring and in many cases helps identify the degree of deposit coking, abnormal events such as acute fouling and inorganics breakthrough. When process conditions (flowrates and temperatures of the streams) are variable, as is common in practice, the reference performance (clean and l-lines) are obtained using a sophisticated dynamic model of the exchanger under fouling. Using a variety of industrial examples, the presentation will illustrate the ability of such a representation and underlying models to resolve the ambiguities of simpler thermal resistance metrics, provide an improved understand
Diaz-Bejarano E, Porsin AV, Macchietto S, 2017, Fossil fuel: Energy efficient thermal retrofit options for crude oil transport in pipelines, The Water-Food-Energy Nexus: Processes, Technologies, and Challenges, Pages: 277-296, ISBN: 9781498760836
Pipelines are used to transport large amounts of crude oil over large distances (either overland or subsea), representing the most economical alternative. Flow assurance faces two main problems: viscosity increase due to gradual cooling of the oil along the pipeline and fouling deposition. These problems are especially important in very cold environments (Russia, Alaska, North Sea, deep oceanic waters, etc.) and when dealing with nonconventional oils, usually heavy or extra-heavy oil and waxy oils. In many cases, the depletion of deposits in conventional oil reservoirs is gradually leading to more extraction of these types of feedstock from remote locations. All these situations result in pipeline transport difficulties such as increased pumping costs, reduced flow rates, and the possibility of flow inhibition or blockage, with potentially major economic impact (Correra et al., 2007; Martínez-Palou et al., 2011).
Coletti F, Diaz-Bejarano E, Macchietto S, et al., 2017, Evaluation, prediction, management and mitigation of fouling in heat exchanger networks for improved energy efficiency, Pages: 3-18
Diaz-Bejarano E, Coletti F, Macchietto S, 2017, Monitoring and analysis of inorganics breakthrough in refinery pre-heat trains, Pages: 335-346
Monitoring of crude oil fouling in refinery heat exchanger typically focus on the gradual decay of thermal performance based on measured temperatures, heat duties or, most commonly, fouling thermal resistances. Such indicators, however, are inherently unable to provide information on the extent, location and composition of the fouling deposits, and therefore to successfully diagnose the underlying causes. The development of monitoring and analysis methods capable of discriminating such effects is particularly important when fouling is due breakthrough of inorganic foulants into the hot end of the preheat train, where organic deposition is usually assumed to be the dominant mechanism. Such problem may be a result of desalter malfunctioning, changes in feedstock or unsuitable management of operations. Here, a novel model-based monitoring and analysis approach is presented. It enables to improve the understanding on how complex deposit structures involving both inorganic and organic species affect the thermo-hydraulic performance of heat exchangers. From an operational stand point it allows the use of primary plant measurements to early detect, and diagnose the underlying causes. Slide 13 and following show and industrial case study in which pressure drop measurements have been used to fit the necessary model parameters (slide 14) and to assess the composition of the fouling layer using thermal (slide 15) and hydraulic (slide 16) predictions. The following slides show how this technique can be used for detection of inorganic breakthrough (slides 17,18, 19) and how this can be used for effective fouling monitoring and diagnosis (slides 20, 21).
Coletti F, Diaz-Bejarano E, Macchietto S, 2017, Heat exchanger design with high shear stress: Evaluating the impact of Performance of Crude Pre-heat Trains, Pages: 167-178
Seegulam N, Coletti F, Macchictto S, 2017, Effect of Fouling on Control and Energy Recovery in an Industrial CDU Column, Editors: Espuna, Graells, Puigjaner, Publisher: ELSEVIER SCIENCE BV, Pages: 1555-1560
Vianello C, Mocellin P, Macchietto S, et al., 2016, Risk assessment in a hypothetical network pipeline in UK transporting carbon dioxide, Journal of Loss Prevention in the Process Industries, Vol: 44, Pages: 515-527, ISSN: 0950-4230
With the advent of Carbon Capture and Storage technology (CCS) the scale and extent of its handling is set to increase. Carbon dioxide (CO2) capture plants are expected to be situated near to power plants and other large industrial sources. Afterward CO2 is to be transported to storage site using one or a combination of transport media: truck, train, ship or pipeline. Transport by pipeline is considered the preferred option for large quantities of CO2 over long distances. The hazard connected with this kind of transportation can be considered an emerging risk and is the subject of this paper.The paper describes the Quantitative Risk Assessment of a hypothetical network pipeline located in UK, in particular the study of consequences due to a CO2 release from pipeline.The risk analysis highlighted that some sections of pipeline network cross densely populated areas. For this reason, some changes in the original path of the network have been proposed in order to achieve a significant reduction in the societal risk.
Diaz-Bejarano E, Coletti F, Macchietto S, 2016, Impact of complex layering structures of organic and inorganic foulants on the thermohydraulic performance of a single heat exchanger tube: a simulation study, Industrial and Engineering Chemistry Research, Vol: 55, Pages: 10718-10734, ISSN: 0888-5885
Crude oil fouling in preheat trains in refineries is usually dominated by organic matter deposition at high temperatures. However, malfunction of desalting equipment, human or technical errors, or changes in feedstock may lead to substantial deposition of inorganic salts or corrosion products, compromising heat exchange performance, pressure drop (hence throughput), and even safety. Understanding how such abnormal deposition and the resulting complex deposit structure affect the thermohydraulic performance of heat exchangers is key to developing adequate monitoring tools for the early detection, diagnosis, and control of the underlying causes. Here, a novel multicomponent fouling deposit formulation is applied to the simulation of deposits composed of organic and inorganic foulants within a single heat exchanger tube. The model enables the tracking of changes and history of local composition in the fouling deposit, thermoconductivity profiles including layering effects, and impact on the overall thermohydraulic performance. The results show that appropriate monitoring of measurable stream conditions, including thermal and hydraulic effects, in combination with reliable predictive fouling and heat exchanger models, allows the detection and (potentially) diagnosing of the abnormal fouling behavior. The model is easily incorporated in full-scale heat exchanger models and is applicable to other processes.
Diaz-Bejarano E, Porsin AV, Macchietto S, 2016, Enhancing the flexibility of pipeline infrastructure to cope with heavy oils: Incremental thermal retrofit, Applied Thermal Engineering, Vol: 105, Pages: 170-179, ISSN: 1359-4311
Pipelines that were well designed for conventional oils may not be able to cope with a transition to heavy oils without some retrofit adaptation, as the increased pressure drop may exceed constraints and force some reduction in throughput. In this paper, ways of enhancing the utilization of existing, capital intensive infrastructure by small, incremental additions are explored. A thermo-hydraulic pipeline model for a buried pipeline is presented. The model is then applied to a case study involving a section of the important, recently built Russia-China ESPO pipeline, for which a gradual shift from the current (design) light oil to heavier oils is considered. A number of thermal retrofit scenarios are proposed and assessed which involve the incremental supply of additional heat at selected points. These scenarios go from pre-heating of the oil at entrance to use of single and multiple intermediate heating stations. The heating duty requirements for each case are calculated. The results show that a careful use of such thermal management techniques can significantly mitigate the reduction in throughput that would otherwise be required, leading to significant economic savings in operations. It is highlighted that the development of adaptable, modular low-cost heating technologies would make this approach significantly advantageous over other alternatives.
Diaz-Bejarano E, Coletti F, Macchietto S, 2016, Crude oil fouling deposition, suppression, removal, and consolidation and how to tell the difference, Heat Transfer Engineering, Vol: 38, Pages: 681-693, ISSN: 0145-7632
Crude oil fouling on heat transfer surfaces is often described as the result of two competing mechanisms: a deposition and a deposition-offsetting mechanism. There is uncertainty about whether the offsetting mechanism is suppression (due inhibition of attachment or back-diffusion of foulant from near the wall into the bulk) or removal of foulant already deposited, due to (i) difficulties in experimentally identifying and isolating the key phenomena and (ii) the cumulative measurement of deposition rates by monitoring thermal exchange rates (or resistance) alone. Here, the question is addressed of whether it is conceptually possible to distinguish such phenomena, and if so, in which conditions. A recently developed two-dimensional (2D) deposit model and a thermohydraulic model of a heat exchanger tube are used to assess the system response to removal, suppression, aging, and consolidation (for which a new model is proposed). It is shown that while suppression or removal lead to undistinguishable behavior during overall deposit growth, thermal and hydraulic responses will differ in certain conditions, for which an experimental procedure is suggested. Simultaneous consideration of thermal and hydraulic effects and accurate characterization of the deposit aging and consolidation processes are suggested as a way to allow the unambiguous identification of the dominant deposition-offsetting mechanism.
Ho WS, Macchietto S, Lim JS, et al., 2016, Optimal scheduling of energy storage for renewable energy distributed energy generation system, Renewable and Sustainable Energy Reviews, Vol: 58, Pages: 1100-1107, ISSN: 1364-0321
Energy storage (ES) is an important device to ensure operation stability and efficiency of a renewable energy based distributed energy generation (DEG) system. As such, many researchers have modelled the operation (scheduling) of energy storage in a DEG system, where it is mostly portrayed to operate on a daily cycle. In this paper, an analysis of the operation mode of energy storage is presented. Two modes of operation are defined, daily mode (DM) (ES operates in daily cycles) and weekly mode (WM) (ES operates in weekly cycles) which are modelled accordingly. This paper then attempts to analyse and compare between both modes in term of operation and cost. The analysis is performed through a mixed integer linear programming (MILP) model programmed via the General Algebraic Modelling System (GAMS). In general, with high capital cost of ES, it is advisable to program the ES to operate in a DM. The reason to this conclusion is mainly due to three factors, intermittency of renewable resources, varying weather conditions, and discharge rate of ES(s).
Diaz-Bejarano E, Coletti F, Macchietto S, 2016, Model-based monitoring of thermal-hydraulic performance of refinery heat exchangers undergoing fouling, Editors: Kravanja, Bogataj, Publisher: ELSEVIER SCIENCE BV, Pages: 1911-1916
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Lanchas-Fuentes L, Diaz-Bejarano E, Coletti F, et al., 2016, Condition-based chemical cleaning of crude oil deposits - a conceptual model, Editors: Kravanja, Bogataj, Publisher: ELSEVIER SCIENCE BV, Pages: 1905-1910
Diaz Bejarano E, Coletti F, Macchietto S, 2015, A new dynamic model of crude oil fouling deposits and its application to the simulation of foulingâcleaning cycles, AIChE Journal, Vol: 62, Pages: 90-107, ISSN: 0001-1541
Modelling of crude oil fouling in heat exchangers has been traditionally limited to a description of the deposit as a thermal resistance. However, consideration of the local change in thickness and the evolution of the properties of the deposit due to ageing or changes in foulant composition is important to capture the thermal and hydraulic impact of fouling. A dynamic, distributed, first-principles model of the deposit is presented that considers it as a multicomponent varying-thickness solid undergoing multiple reactions. For the first time, full cleaning, partial cleaning, and fouling resumption after cleaning can be simulated in any order with a single deposit model. The new model, implemented within a single tube framework, is demonstrated in a case study where various cleaning actions are applied following a period of organic deposition. It is shown that complete mechanical cleaning and chemical cleaning of different extent, according to a condition-based efficacy, can be seamlessly simulated.
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