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1
Coetzee, W. A. S. "Steam systems network synthesis using process integration." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-08252008-165312/.
Повний текст джерела
2
Viljoen, Johannes Henning. "Dynamic Modelling and Hybrid Non-Linear Model Predictive Control of Induced Draft Cooling Towers With Parallel Heat Exchangers, Pumps and Cooling Water Network." Thesis, University of Pretoria, 2019. http://hdl.handle.net/2263/72415.
Повний текст джерелаАнотація:
In the process industries, cooling capacity is an important enabler for the facility to manufacture on specification product. The cooling water network is an important part of the over-all cooling system of the facility. In this research a cooling water circuit consisting of 3 cooling towers in parallel, 2 cooling water pumps in parallel, and 11 heat exchangers in parallel, is modelled. The model developed is based on first principles and captures the dynamic, non-linear, interactive nature of the plant. The modelled plant is further complicated by continuous, as well as discrete process variables, giving the model a hybrid nature. Energy consumption is included in the model as it is a very important parameter for plant operation. The model is fitted to real industry data by using a particle swarm optimisation approach. The model is suitable to be used for optimisation and control purposes.
Cooling water networks are often not instrumented and actuated, nor controlled or optimised. Significant process benefits can be achieved by better process end-user temperature control, and direct monetary benefits can be obtained from electric power minimisation. A Hybrid Non-Linear Model Predictive Control strategy is developed for these control objectives, and simulated on the developed first principles dynamic model. Continuous and hybrid control cases are developed, and tested on process scenarios that reflect conditions seen in a real plant.
Various alternative techniques are evaluated in order to solve the Hybrid Non-Linear Control problem. Gradient descent with momentum is chosen and configured to be used to solve the continuous control problem. For the discrete control problem a graph traversal algorithm is developed and joined to the continuous control algorithm to form a Hybrid Non-Linear Model Predictive controller. The potential monetary benefits that can be obtained by the plant owner through implementing the designed control strategy, are estimated. A powerful computation platform is designed for the plant model and controller simulations.Thesis (PhD)--University of Pretoria, 2019.
Electrical, Electronic and Computer Engineering
PhD
Unrestricted
3
Filho, Luiz Omena de Oliveira. "Uma abordagem matricial para modelagem e simulação de redes de trocadores de calor com aplicações para o gerenciamento da deposição." Universidade do Estado do Rio de Janeiro, 2007. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=7243.
Повний текст джерелаАнотація:
Uma rede de trocadores de calor pode ser definida como um grupo de trocadores de calor interligados com o objetivo de reduzir a necessidade de energia de um sistema, sendo largamente usada nas indústrias de processos. Entretanto, uma rede está sujeita à deposição, a qual causa um decréscimo na efetividade térmica dos trocadores. Este fenômeno é provocado pelo acúmulo de materiais indesejáveis sobre a superfície de troca térmica. Para compensar a redução de efetividade térmica causada pela deposição, torna-se necessário um aumento no consumo de utilidades. Isto eleva os custos de operação, assim como os custos de manutenção. Estima-se que os custos associados à deposição atinjam bilhões de dólares anualmente. Em face a este problema, vários trabalhos de pesquisa têm investigado métodos para prevenir a deposição e/ou gerenciar as operações em uma rede. Estudos envolvem desde a otimização de trocadores de calor individuais, simulação e monitoramento de redes, até a otimização da programação das paradas para limpeza de trocadores de calor em uma rede. O presente trabalho apresenta a proposição de um modelo para simulação de redes de trocadores de calor com aplicações no gerenciamento da deposição. Como conseqüência, foi desenvolvido um conjunto de códigos computacionais integrados, envolvendo a simulação estacionária de redes, a simulação pseudo-estacionária do comportamento de redes em relação à evolução da deposição, a estimação de parâmetros para diagnóstico do problema da deposição e a otimização operacional deste tipo de sistema. Com relação ao simulador estacionário, o modelo da rede foi formulado matricialmente e os balanços de massa e energia são resolvidos como sistemas de equações lineares. Do ponto de vista da otimização, o procedimento proposto redistribui as vazões, visando um melhor aproveitamento térmico dos trocadores da rede, como, por exemplo, buscando as vazões da rede que maximizem a temperatura da corrente de entrada no forno em unidades de destilação atmosférica de óleo cru. Os algoritmos foram implementados em alguns exemplos da literatura e em um problema de uma refinaria real. Os resultados foram promissores, o que sugere que a proposta deste trabalho pode vir a ser uma abordagem interessante para operações envolvendo redes de trocadores de calorA Heat Exchanger Network (HEN) can be defined as a group of heat exchangers interconnected aiming to reduce the energy demand of a system, being widely used in the process industries. However, a HEN is subject to fouling, which causes a decrease on the thermal effectiveness of heat exchangers. This phenomenon is provoked by the accumulation of undesirable materials on thermal surface. In order to compensate the reduction of thermal effectiveness caused by fouling, it becomes necessary to increase the utility consumption. Thus, there is an increase of the operation costs, as maintenance costs. It is estimated that the costs associated to fouling reach billions of dollars annually. Facing this problem, several researches have investigated methods to prevent fouling and/or how to manage HEN operations. Studies involve since optimization of individual heat exchangers, simulation and fouling monitoring, until cleaning schedule optimization of HENs. The present work proposes a HEN simulation model, applied to fouling management. Consequently, it was developed a set of integrated computational codes, which involve a HEN stationary simulation, a pseudo-stationary simulation of HEN behavior related to fouling, a parameter estimation procedure for diagnosing fouling problems and an operational optimization procedure of this sort of system. Related to the stationary simulator, the HEN model is formulated using a matrix approach and the mass and energy balances are solved as linear equation systems. Focusing on optimization, it redistributes the HEN flows in order to improve the heat exchangers thermal efficiency, for example, searching for the HEN flows that maximize the inlet furnace stream temperature in crude distillation units. The algorithm was implemented to some literature examples and on a problem of a real refinery. All results show to be promising, which suggests that the proposal of this work may be an interesting approach for operations involving HENs
4
Wang, Yufei. "Heat exchanger network retrofit through heat transfer enhancement." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/heat-exchanger-network-retrofit-through-heat-transfer-enhancement(c504dc06-f261-4968-8c58-4f4de153c694).html.
Повний текст джерелаАнотація:
Heat exchanger network retrofit plays an important role in energy saving in process industry. Many design methods for the retrofit of heat exchanger networks have been proposed during the last three decades. Conventional retrofit methods rely heavily on topology modifications which often results in a long retrofit duration and high initial costs. Moreover, the addition of extra surface area to the heat exchanger can prove difficult due to topology, safety and downtime constraints. These problems can be avoided through the use of heat transfer enhancement in heat exchanger network retrofit. This thesis develops a heuristic methodology and an optimization methodology to consider heat transfer enhancement in heat exchanger network retrofit. The heuristic methodology is to identify the most appropriate heat exchangers requiring heat transfer enhancements in the heat exchanger network. From analysis in the heuristic roles, some great physical insights are presented. The optimisation method is based on simulated annealing. It has been developed to find the appropriate heat exchangers to be enhanced and to calculate the level of enhancement required. The new methodology allows several possible retrofit strategies using different retrofit methods be determined. Comparison of these retrofit strategies demonstrates that retrofit modification duration and pay-back time are reduced significantly when only heat transfer enhancement is utilised. Heat transfer enhancement may increase pressure drop in a heat exchanger. The fouling performance in a heat exchanger will also be affected when heat transfer enhancement is used. Therefore, the implications of pressure drop and fouling are assessed in the proposed methodology predicated on heat transfer enhancement. Methods to reduce pressure drop and mitigate fouling are developed to promote the application of heat transfer enhancement in heat exchanger network retrofit. In optimization methodology considering fouling, the dynamic nature of fouling is simulated by using temperature intervals. It can predict fouling performance when heat transfer enhancement is considered in the network. Some models for both heat exchanger and heat transfer enhancement are used to predict the pressure drop performance in heat exchanger network retrofit. Reducing pressure by modifying heat exchanger structure is proposed in this thesis. From case study, the pressure drop increased by heat transfer enhancement can be eliminated by modifying heat exchanger structure.
5
Tjoe, T. N. "Retrofit of heat exchanger networks." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376507.
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Бухкало, Светлана Ивановна, та Оксана Игоревна Ольховская. "Анализ возможностей комплексных технологий утилизации полимерной части твердых бытовых отходов". Thesis, Московский государственный университет дизайна и технологии, 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/22983.
Повний текст джерелаАнотація:
Рассмотрены основные системы газификационных агрегатов большой единичной мощности. Выделены основные логистические факторы, влияющие на технологические схемы газификационных агрегатов такие, как природа, качество и состав газифицирующего сырья, номенклатура целевых продуктов, экологические требования по вредным выбросам и эмиссии парниковых газов, местоположение агрегата относительно крупных производственных комплексов, возможности конверсии отходов в полезные продукты.The basic heat exchangers networks of big gasification plants with entrained-flow fuel gasification are considered. The main logistical factors that influence on process of gasification plants are underlined such fs nature quality and components content of fuel to be gasified, range of target products, environmental legislation and demands including greenhouse gases emission, location relatively to big industrial sites, possibilities of wastes conversion into saleable products.
7
O'Young, D. Lionel. "Constrained heat exchanger network : targeting and design." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386405.
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Kotjabasakis, E. "Design of flexible heat exchanger networks." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235140.
Повний текст джерелаАнотація:
Design for process flexibility is an industrially important topic so it is not surprising that it is attracting much research work. Given the size of the problem it is also not surprising that workers have concentrated on heat exchanger networks, which can be considered to be a self-contained sub-problem. Unfortunately, recent research has suffered from a number of major drawbacks. Problem formulation has often been unrealistic. Proposed procedures tend to be 'clinical' rather than practical. Academic research has often been conducted without proper consideration of the industrial environment. Very few research results have been tested on full scale industrial problems. In this thesis a new problem formulation and new solution techniques are presented. They have been designed to fulfil the needs of industry. In problem formulation it is recognised that the specification of flexibility is primarily an economic problem. The amount of flexibility industry will demand is a function of how much it costs. The methodology developed here allows both, the flexibility cost and the existing trade-off between flexibility needs, capital costs and energy costs to be fully evaluated. Flexibility problem formulation is mainly based on Multiple Base Cases. Different plant operating scenarios are set and a design found that is able to satisfy each case. This is a formulation that has found a wide acceptance in industry. To be industrially practical, process design techniques must be intelligible to the non-specialist. The techniques developed here are simple and straightforward and give insight. Two new design techniques have been developed. The first of these is 'Downstream Paths'. These are used to identify and evolve the network structures that permit cost effective flexibility. The second technique is 'Sensitivity Tables'. These can be used to analyse the performance of a given structure. In addition they determine the cost effective modification to elements of the structure which provide the specified flexibility needs. The technique is rapid, simple to apply and easy to repeat. Consequently, many scenarios can be screened without much effort and a cost profile developed in order to evaluate the cost trade-off described above. The approach proposed in this thesis, involving the new problem formulation and solution techniques, has been applied to a number of case studies of industrial scale. These case studies have covered problems as diverse as catalyst deactivation, fouling, and plant debottlenecking. One major spin-off from the work is a new approach to the design of heat exchanger networks subjected to fouling. Large potential savings have been identified.
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Zhu, Xin X. "Strategies for optimization in heat exchanger network design /." Title page, contents and summary only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phz638.pdf.
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Al, Ismaili Riham. "Optimisation of heat exchanger network maintenance scheduling problems." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/280281.
Повний текст джерелаАнотація:
This thesis focuses on the challenges that arise from the scheduling of heat exchanger network maintenance problems which undergo fouling and run continuously over time. The original contributions of the current research consist of the development of novel optimisation methodologies for the scheduling of cleaning actions in heat exchanger network problems, the application of the novel solution methodology developed to other general maintenance scheduling problems, the development of a stochastic programming formulation using this optimisation technique and its application to these scheduling problems with parametric uncertainty. The work presented in this thesis can be divided into three areas. To efficiently solve this non-convex heat exchanger network maintenance scheduling problem, new optimisation strategies are developed. The resulting contributions are outlined below. In the first area, a novel methodology is developed for the solution of the heat exchanger network maintenance scheduling problems, which is attributed towards a key discovery in which it is observed that these problems exhibit bang-bang behaviour. This indicates that when integrality on the binary decision variables is relaxed, the solution will tend to either the lower or the upper bound specified, obviating the need for integer programming solution techniques. Therefore, these problems are in ac- tuality optimal control problems. To suitably solve these problems, a feasible path sequential mixed integer optimal control approach is proposed. This methodology is coupled with a simple heuristic approach and applied to a range of heat exchanger network case studies from crude oil refinery preheat trains. The demonstrated meth- odology is shown to be robust, reliable and efficient. In the second area of this thesis, the aforementioned novel technique is applied to the scheduling of the regeneration of membranes in reverse osmosis networks which undergo fouling and are located in desalination plants. The results show that the developed solution methodology can be generalised to other maintenance scheduling problems with decaying performance characteristics. In the third and final area of this thesis, a stochastic programming version of the feasible path mixed integer optimal control problem technique is established. This is based upon a multiple scenario approach and is applied to two heat exchanger network case studies of varying size and complexity. Results show that this methodology runs automatically with ease without any failures in convergence. More importantly due to the significant impact on economics, it is vital that uncertainty in data is taken into account in the heat exchanger network maintenance scheduling problem, as well as other general maintenance scheduling problems when there is a level of uncertainty in parameter values.
11
Salihu, Adamu Girei. "Optimal design and operation of heat exchanger network." Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9850.
Повний текст джерелаАнотація:
Heat exchanger networks (HENs) are the backbone of heat integration due to their ability in energy and environmental managements. This thesis deals with two issues on HENs. The first concerns with designing of economically optimal Heat exchanger network (HEN) whereas the second focus on optimal operation of HEN in the presence of uncertainties and disturbances within the network. In the first issue, a pinch technology based optimal HEN design is firstly implemented on a 3–streams heat recovery case study to design a simple HEN and then, a more complex HEN is designed for a coal-fired power plant retrofitted with CO2 capture unit to achieve the objectives of minimising energy penalty on the power plant due to its integration with the CO2 capture plant. The benchmark in this case study is a stream data from (Khalilpour and Abbas, 2011). Improvement to their work includes: (1) the use of economic data to evaluate achievable trade-offs between energy, capital and utility cost for determination of minimum temperature difference; (2) redesigning of the HEN based on the new minimum temperature difference and (3) its comparison with the base case design. The results shows that the energy burden imposed on the power plant with CO2 capture is significantly reduced through HEN leading to utility cost saving maximisation. The cost of addition of HEN is recoverable within a short payback period of about 2.8 years. In the second issue, optimal HEN operation considering range of uncertainties and disturbances in flowrates and inlet stream temperatures while minimizing utility consumption at constant target temperatures based on self-optimizing control (SOC) strategy. The new SOC method developed in this thesis is a data-driven SOC method which uses process data collected overtime during plant operation to select control variables (CVs). This is in contrast to the existing SOC strategies in which the CV selection requires process model to be linearized for nonlinear processes which leads to unaccounted losses due to linearization errors. The new approach selects CVs in which the necessary condition of optimality (NCO) is directly approximated by the CV through a single regression step. This work was inspired by Ye et al., (2013) regression based globally optimal CV selection with no model linearization and Ye et al., (2012) two steps regression based data-driven CV selection but with poor optimal results due to regression errors in the two steps procedures. The advantage of this work is that it doesn’t require evaluation of derivatives hence CVs can be evaluated even with commercial simulators such as HYSYS and UNISIM from among others. The effectiveness of the proposed method is again applied to the 3-streams HEN case study and also the HEN for coal-fired power plant with CO2 capture unit. The case studies show that the proposed methodology provides better optimal operation under uncertainties when compared to the existing model-based SOC techniques.
12
Vizcaino-Garcia, Fidel. "Control strategies for flexible heat exchanger networks." Thesis, University of Manchester, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503089.
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Yeap, Boon Lin. "Designing heat exchanger networks to mitigate fouling." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615934.
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Hattingh, Caleb. "On the operability of heat exchanger networks." Master's thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/5320.
Повний текст джерелаАнотація:
Bibliography: leaves 127-132.The dynamic operability of processes refers to the degree to which plants may be satisfactorily controlled. This report presents a study of the operability of heat exchanger networks (HENs).The integration of heat exchange systems such as HENs typically results in significant steady-state cost savings which is the motivation for their implementation. However, such integration may lead to problems in the dynamic operation of the system if the operability of HENs is not considered. Operability analysis techniques are presented that provide a quantitative measure of the operability of HENs that is related to the minimum integral setpoint error of a closed-loop HEN under a step disturbance. The different operability analysis techniques are specified by ,u sing different controller types which are optimally tuned in an optimization framework. The different controllers include PI (proportionalintegral) control, MPC (model predictive control), optimal linear control (via Qparametrization) and an optimal open-loop control strategy that represents the best possible closed-loop performance.
15
Beautyman, Alan Clive. "The design of flexible heat exchanger networks." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/7586.
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Morton, R. J. "Practical heat exchanger networks : capital cost, exchanger type and utilities." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239341.
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Al-Hindi, Mahmoud. "Operating strategies for heat exchangers and networks of heat exchangers subject to fouling and variable inlet conditions." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321935.
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Hepworth, Simon. "Hybrid neural control of heat exchangers in HVAC plant." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260138.
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19
Akpomiemie, Mary Onome. "Cost effective retrofit methods for heat exchanger networks." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/cost-effective-retrofit-methods-for-heat-exchanger-networks(19a15828-0bb8-44ca-9669-be590409bd88).html.
Повний текст джерелаАнотація:
Improving the energy efficiency of process plants is central to minimising operatingcosts and increasing profitability. Growing concerns on climate change is also anissue due to the increasing level of carbon dioxide emissions. Process industriesremain one of the largest consumers of energy. Maximising energy recovery in heatexchanger networks (HENs) reduce the total energy consumption in processindustries. However, cost effective retrofit of HENs remains a great challenge. Anideal retrofit design is one that has the right balance between efficient use of existingequipment and limited amount of modifications and downtime, while maximisingenergy recovery. The key objective of this thesis is to present novel methodologiesfor cost effective retrofit of HENs, while ensuring industrial applicability. The cost associated with the application of structural modifications and additionalheat transfer area, has led to an increased interest into the use of heat transferenhancement for retrofit. Heat transfer enhancement is beneficial, as it usuallyrequires low capital investment for fixed network topology, and no additional heattransfer area in existing heat exchangers. However, the challenges of heat transferenhancement for industrial applications are: (1) identifying the best heat exchangerto enhance; (2) dealing with downstream effects on the HEN after applyingenhancement; and (3) dealing with its effect on pressure drop. This thesis presentssequential based methodologies consisting of a combination of heuristics and a profitbased non-linear optimisation model for tackling these three issues. The robustnessof the new approach lies in its ability to provide useful insights into the interaction ofvarious units in a HEN whilst being pertinent for automation. Notwithstanding the drawbacks of structural modifications in retrofit, the degree ofenergy savings that can be obtained cannot be ignored. A robust retrofit strategy forthe application of structural modifications in retrofit is required. This thesis presentsa methodology that provides new fundamental insights into the application ofstructural modifications that ultimately leads to a faster retrofit procedure, withoutcompromising the performance and feasibility of the retrofitted HEN. The newapproach: (1) identifies the best location to apply a series of modifications; and (2)presents an algorithm that can be automated for the identification of the best singleand multiple modifications that provides maximum energy recovery for a givenHEN. The robustness of the new approach is tested by a comparison with the wellestablishedstochastic optimisation approach for structural modifications i.e.simulated annealing. To improve the retrofit result, this work also considerscombining the use of structural modifications and heat transfer enhancement. Theaim is to harnesses the benefits of both methods to obtain a cost effective retrofitdesign. The analysis carried out in this work is subject to minimising the energyconsumption and maximising the retrofit profit. A decision on the best retrofitstrategy to apply to a given HEN depends on the given retrofit objective. However,this work provides an adequate basis on which the decision can be made based onindustrial applicability, profit and energy saving.
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Oliver, Jacobus Coenraad. "Network modelling of transient heat exchanger performance / Jacobus C. Olivier." Thesis, North-West University, 2005. http://hdl.handle.net/10394/490.
Повний текст джерелаАнотація:
This study investigates the applicability of the thermal-fluid network approach to the modelling of transient
heat exchanger performance.
Two different solution algorithms, namely the Implicit Pressure Correction Method (IPCM) and the Runge
Kutta method with Trapezoidal Damping (RKTD) for the solution of the one-dimensional governing equations
in thermal-fluid network problems are presented. The advantages and disadvantages of two types of
numerical discretisation schemes used in thermal-fluid network problems are discussed and the discretised
one-dimensional governing equations for the staggered grid discretisation scheme used in the IPCM and
RKTD method is presented. The RKTD method is used as a time integration scheme for the generalised
thermal-fluid network solver Xnet. Several test cases are introduced and the basic primitive elements
available in Xnet are compared to the commercial thermal-fluid network code, Flownex (which uses the
IPCM), for both steady-state and transient conditions.
Two different network topologies are introduced for the discretisation of heat exchangers when a network
approach is followed and the thermal-fluid network solver Xnet is applied to a basic parallel and counter flow
configured pipe-in-pipe type heat exchanger to investigate the effect on the type of discretisation scheme
used. The results obtained are compared to primitive element models in Flownex as well as the composite
RX element in Flownex.
The extent to which thermal-fluid network solvers are able to predict transient heat exchanger performance
are further investigated by modelling a complex shell-and-tube heat exchanger using Xnet and comparing
the steady-state and transient results to both a primitive element model in Flownex as well as the composite
STX element in Flownex. This contributes to the validation of Flownex’s heat exchanger models by using a
different approach than Flownex.
The results showed that the explicit method used in Xnet is capable of solving large arbitrary structured
thermal-fluid networks with a high level of accuracy. The result of Flownex compares very well with that of
Xnet, which proves (verifies) that the solution algorithm is correctly implemented in both codes. Even though
the explicit thermal-fluid network code, Xnet, can accurately predict fast transients, a drawback of this
method is the large computational time required to simulate transient heat exchangers with large thermal
masses.Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2005.
21
Mandela, Ravi Kumar. "Uncertainty analysis of piping systems and heat exchanger networks." abstract and full text PDF (free order & download UNR users only), 2004. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1433382.
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Tantimuratha, L. "Automated design of flexible and operable heat exchanger networks." Thesis, University of Manchester, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505685.
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Asante, N. D. R. "Automated and interactive retrofit designof practical heat exchanger networks." Thesis, University of Manchester, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504897.
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Ahmad, S. "Heat exchanger networks : Cost tradeoffs in energy and capital." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376511.
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Colberg, Richard Dale Morari Manfred Morari Manfred. "Area, cost and resilience targets for heat exchanger networks /." Diss., Pasadena, Calif. : California Institute of Technology, 1989. http://resolver.caltech.edu/CaltechETD:etd-02062007-104756.
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Dhallu, N. S. "Synthesis of process designs with potential for heat integration." Thesis, London South Bank University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233001.
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Jegede, Felix Olarewaju. "Power, capital and energy costs trade-offs in heat exchanger networks." Thesis, University of Manchester, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277204.
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Nie, Xiu-Rong. "Optimisation strategies for heat exchanger network design considering pressure drop aspects." Thesis, University of Manchester, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503543.
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Yang, Rupu. "Methodology for developing flexible, controllable and cost-effective heat exchanger network." Thesis, Université Paris sciences et lettres, 2020. http://thesesprivees.mines-paristech.fr/2020/2020UPSLM011_archivage.pdf.
Повний текст джерелаАнотація:
Cette thèse a pour objectif de considérer les performances dynamiques d’un réseau d'échangeurs de chaleur (HEN) lors de sa conception. Nous définissons le temps de transition (TT) comme un indicateur pour mesurer les performances dynamiques lorsque le HEN subit des variations opérationnelles. La thèse vise à résoudre deux problèmes: comment estimer le TT d'un HEN donné; et comment réaliser la conception pour optimiser le coût du HEN, ce qui nous permet d'obtenir un compromis entre le coût et le TT. En nous appuyant sur la transformation de Laplace, nous développons une formulation mathématique pour déterminer TT, et cela conduit à deux modèles dynamiques. Le modèle de base nécessite le processus de transformation inverse de Laplace. Le deuxième modèle, plus avancé, est basé sur des développements purement analytiques afin d’éviter la difficulté numérique de la transformation inverse de Laplace. Les méthodes de synthèse suivent l'approche séquentielle multi-période pour itérer différentes structures, puis le TT peut être calculé pour chaque HEN optimisé en coût. Nous proposons deux méthodes d'itération: BINLP pour le petit cas et IINLP pour les problèmes de moyenne à grande échelle. Les méthodes de synthèse et les modèles dynamiques HEN ont été appliqués avec succès dans cinq études de cas à travers différents chapitres, et nous constatons que le TT varie énormément selon les structures testés. Il est important de prendre en compte le temps de transition dans le problème de conception de HEN, et nos méthodes proposées peuvent servir d'outil de présélection pour aider à trier des HEN en termes de coût et de performances dynamiquesThis thesis pioneers to consider the time response in the heat exchanger network (HEN) multi-period design problem. We define the transition time (TT) as an indicator to measure the dynamic performance when HEN gets an operational period changeover. The thesis aims to solve two problems: how to measure the TT of a given HEN; and how to carry out synthesis work to optimize the HEN cost, allowing us to obtain a trade-off between the cost and TT. Relying on the Laplace transform, we develop a mathematical formulation to reach TT, leading to two dynamic models. The basic one requires the inverse Laplace transform process during the calculation. The improved dynamic model follows the analytic way, and free of the concern of the numerical difficulty of the inverse Laplace transform. The synthesis methods follow the sequential approach to iterate various structures and then TT can be calculated for each cost-optimized HEN. We propose two iteration methods: BINLP for the small case and IINLP for medium-large scale problems. The synthesis methods and HEN dynamic models were applied successfully in five case studies through different chapters, and found that TT varied hugely for different designs in each case. It is important to consider the time response in the HEN design problem, and our proposed methods can act as a pre-selection tool to help sort out those designs in terms of the cost and dynamic performances
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Shokoya, Celestina Gbeminiyi. "Retrofit of heat exchanger networks for bebottlenecking and energy savings." Thesis, University of Manchester, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306291.
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Calandranis, John Christos. "Operability studies in heat exchanger networks : analysis, control and synthesis." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14393.
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Briones, Vallejo V. M. "An integrated framework for the design of heat exchanger networks." Thesis, University of Manchester, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.570535.
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Payne, Russell. "The application of artificial neural networks to combustion and heat exchanger systems." Thesis, University of South Wales, 2005. https://pure.southwales.ac.uk/en/studentthesis/the-application-of-artificial-neural-networks-to-combustion-and-heat-exchanger-systems(684a7758-1b1c-4560-8df1-e482b42ef8a2).html.
Повний текст джерелаАнотація:
The operation of large industrial scale combustion systems, such as furnaces and boilers is increasingly dictated by emission legislation and requirements for improved efficiency. However, it can be exceedingly difficult and time consuming to gather the information required to improve original designs. Mathematical modelling techniques have led to the development of sophisticated furnace representations that are capable of representing combustion parameters. Whilst such data is ideal for design purposes, the current power of computing systems tends to generate simulation times that are too great to embed the models into online control strategies. The work presented in this thesis offers the possibility of replacing such mathematical models with suitably trained Artificial Neural Networks (ANNs) since they can compute the same outputs at a fraction of the model's speed, suggesting they could provide an ideal alternative in online control strategies. Furthermore, artificial neural networks have the ability to approximate and extrapolate making them extremely robust when encountering conditions not met previously. In addition to improving operational procedures, another approach to increasing furnace system efficiency is to minimise the waste heat energy produced during the combustion process. One very successful method involves the implementation of a heat exchanger system in the exiting gas flue stream, since this is predominantly the main source of heat loss. It can be exceptionally difficult to determine which heat exchanger is best suited for a particular application and it can prove an even more arduous task to control it effectively. Furthermore, there are many factors that alter the performance characteristics of a heat exchanger throughout the duration of its operational life, such as fouling or unexpected systematic faults. This thesis investigates the modelling of an experimental heat exchanger system via artificial neural networks with a view to aiding the design and selection process. Moreover, the work presented offers a means to control heat exchangers subject to varying operating conditions more effectively, thus promoting savings in both waste energy and time.
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Pua, Lee M. "Overall optimisation framework for multi-stream plate-fin heat exchanger network synthesis." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506290.
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Ochoa-Estopier, Lluvia Marisol. "Optimisation of existing heat-integrated crude oil distillation systems." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/optimisation-of-existing-heatintegrated-crude-oil-distillation-systems(88b5ce92-d472-43be-9956-9ad833b96673).html.
Повний текст джерелаАнотація:
Crude oil distillation is an energy intensive and environmentally challenging process. To decrease the large energy demand of crude oil distillation, heat integration is implemented. The system (i.e. distillation unit and heat exchanger network, HEN) needs to perform an energy-efficient separation in a broad range of scenarios (e.g. changes in product yields or product specifications), without compromising overall profit. Operational optimisation and revamp projects are frequently implemented to adapt an existing system to such diverse scenarios. The present work provides a new approach for optimising crude oil distillation systems. The scope of this methodology consists of: 1) finding the operating conditions for the distillation system that maximise net profit, while 2) proposing retrofit modifications for the HEN that allow a feasible operation. Artificial neural networks (ANN) are used to represent the distillation process. In the proposed modelling strategy, results of rigorous simulations provide the data used to train the ANN models. The resulting ANN models have the advantages of overcoming convergence problems presented by both rigorous and simplified models, of handling fewer variables and performing calculations in less time. The HEN models used in this work consist of a retrofit model and a simulation model. The HEN retrofit model employed by Chen (2008) is extended to include constraints on heat transfer areas, utility consumption; and to optimise stream split fractions. In addition, the segmented linear data used by Chen (2008) to calculate temperature-dependent heat capacities are replaced by models tailor-made for each stream. This allows a more flexible and accurate representation of these properties, compared to the approach of Chen (2008). The HEN simulation model of de Oliveira Filho et al. (2007) is modified and extended in this work to simulate simple unit operations and to consider heat exchangers specified in terms of heat loads. Distillation, HEN and economic models are implemented in a two-level optimisation framework. The first level consists of a simulated annealing algorithm that optimises the operating conditions of the distillation unit (e.g. flow rates of products and stripping steam, pump-around duties and temperature drops, furnace exit temperature) and HEN topology (i.e. number and location of heat exchangers and stream splitters). The second level solves a non-linear least squares problem that addresses the violation of HEN constraints. Different objective functions can be considered, such as maximising net profit or minimising total annualised costs. The case studies presented in this work show that ANN models are suitable for their implementation in optimisation methodologies for crude oil distillation systems. Results indicate that interactions between the distillation process and HEN are captured, and that significant economic improvements can be achieved with the proposed optimisation approach.
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Kirkizoglu, Isil. "Heat Exchanger Network Synthesis With Detailed Design: Reformulation As A Shortest Path Problem By Temperature Discretization." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614877/index.pdf.
Повний текст джерелаАнотація:
This study presents an optimization approach to heat exchanger network synthesis (HENS). HENs are widely used in industry and bring several fluid streams into their desired temperatures by using available heat in the process for efficient usage of energy. Our aim is to provide a network design coupled with a detailed equipment design for heat exchangers. The suggested approach involves discretization of temperatures based on heat load equalities and reformulation as a shortest-path problem, rather than dealing with a nonlinear model and a previously structured HEN, which are common methods in the literature.
We generate a shortest path network whose every node corresponds to a heat exchanger alternative and each path represents a HEN design alternative. A mixed-integer nonlinear programming model is solved to design each exchanger alternative in detail, considering all thermo-physical and transport properties of streams at their temperatures and pressures. Our approach has modeling flexibility and successfully finds the required number of heat exchangers and their connections. In addition, one can control the solution quality by deciding on the heat load steps between stream inlet and outlets. Several HEN examples from the literature are solved to assess the performance of our approach and comparable results are obtained.
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Li, Kequn [Verfasser]. "The Dynamic Behaviour of Multi-Stream Heat Exchangers and their Networks / Kequn Li." Aachen : Shaker, 2004. http://d-nb.info/1170539483/34.
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Jones, Paul Simon. "Targeting and design for heat exchanger networks under multiple base case operation." Thesis, University of Manchester, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292518.
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Hanson, Keith William. "The synthesis of heat exchanger networks subject to variable sets of constraints." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/8166.
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Leruth, Alexandre. "Heat exchanger network self-optimising control : Application to the crude unit at Mongstad refinery." Thesis, Norges Teknisk-Naturvitenskaplige Universitet, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-21108.
Повний текст джерелаАнотація:
This work applies the concept of self-optimising control for the operation of the given network. The steady-state performances of the self-optimising variables derived by Jäschke (Jäschke, 2012) are assessed and two main control configurations are examined: a simple decentralised control configuration (PIDs Control) and an advanced multivariable control configuration (Model Predictive Control). The steady-state performances appears to be moderate but need to be re-assessed using a proper steady-state model. The decentralised control configuration is found to present acceptable dynamic performances while the advanced multivariable configuration only enhances them a bit.
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Isafiade, Adeniyi Jide. "Interval based MINLP superstructure synthesis of heat and mass exchange networks." Doctoral thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/5315.
Повний текст джерелаАнотація:
Includes abstract.Includes bibliographical references (leaves 153-157).
Name inverted on t.p.
This study presents a new technique for synthesizing heat and mass exchange networks. The method involves generating superstructures using the temperature/composition interval concept from the physical insight approach. The superstructures are partitioned into temperature/composition intervals using the supply and target temperatures/compositions of either the hot/rich or cold/lean set of streams. The opposite kind of streams are made to participate (float) in all the intervals defined. Their ability to exchange heat/mass in these intervals is however subject to thermodynamic feasibility. The resulting superstructure is optimised as a mixed integer non linear programming (MINLP) model. The superstructure is hot/rich streams based if hot/rich streams are used to define the intervals otherwise it is cold/lean stream based.
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Georgiadis, Michael. "Advanced optimisation of batch plant design and operation." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/7394.
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Biruk, David D. "Neural Network Based Control of Integrated Recycle Heat Exchanger Superheaters in Circulating Fluidized Bed Boilers." UNF Digital Commons, 2013. http://digitalcommons.unf.edu/etd/470.
Повний текст джерелаАнотація:
The focus of this thesis is the development and implementation of a neural network model predictive controller to be used for controlling the integrated recycle heat exchanger (Intrex) in a 300MW circulating fluidized bed (CFB) boiler. Discussion of the development of the controller will include data collection and preprocessing, controller design and controller tuning. The controller will be programmed directly into the plant distributed control system (DCS) and does not require the continuous use of any third party software.
The intrexes serve as the loop seal in the CFB as well as intermediate and finishing superheaters. Heat is transferred to the steam in the intrex superheaters from the circulating ash which can vary in consistency, quantity and quality. Fuel composition can have a large impact on the ash quality and in turn, on intrex performance. Variations in MW load and airflow settings will also impact intrex performance due to their impact on the quantity of ash circulating in the CFB. Insufficient intrex heat transfer will result in low main steam temperature while excessive heat transfer will result in high superheat attemperator sprays and/or loss of unit efficiency.
This controller will automatically adjust to optimize intrex ash flow to compensate for changes in the other ash properties by controlling intrex air flows. The controller will allow the operator to enter a target intrex steam temperature increase which will cause all of the intrex air flows to adjust simultaneously to achieve the target temperature. The result will be stable main steam temperature and in turn stable and reliable operation of the CFB.
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Azeez, Oluwatosin Sarafa. "Supply and target-based superstructure synthesis of heat and mass exchange networks." Doctoral thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/5342.
Повний текст джерелаАнотація:
Includes abstract.Includes bibliographical references.
This study presents three new methods for superstructure synthesis of heat exchanger networks (HENs) and mass exchanger networks (MENs) that involve the use of key parameters in HEN and MEN to define superstructure intervals. The key parameters are the stream supply and target temperatures/compositions. The Supply-Based Superstructure (SBS) uses the supply temperatures/compositions of both the hot/rich streams and the cold lean streams. The Supply and Target-Based Superstructure (S&TBS) uses the supply temperatures/compositions of hot/rich streams and the target temperatures/compositions of cold/lean streams for the definition of the superstructure intervals. The Target and Supply-Based Superstructure (T&SBS) uses the target temperatures/compositions of hot/rich streams and the supply temperatures/compositions of cold/lean streams for the definition of the superstructure interval boundaries.
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Ndwandwe, Khaya. "A spreadsheet-based tool for synthesis of heat and mass exchange networks." Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/5984.
Повний текст джерелаАнотація:
Includes bibliography.The objective of this project was to develop a user-friendly program for applying Pinch Technology approach to both Heat Exchanger Networks Synthesis (HENS) and Mass Exchanger Networks Synthesis (MENS) for use by ordinary engineers. Pinch Technology is a structure independent approach.
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Gcabva, Sibusiso Joshua. "Design of consistently near-optimal heat exchanger networks by a two-stage optimisation approach." Master's thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/21776.
Повний текст джерелаАнотація:
Bibliography: pages 225-231.Research in the field of Heat Exchanger Network Synthesis has been active as far back as 1965. Although the problem statement has remained essentially unchanged since then, numerous techniques have been developed to solve the heat exchange problem. Despite significant progress achieved over the years, a number of design issues remain unresolved or vaguely understood. Consequently, consistent generation of near-optimal heat exchanger networks is not guaranteed. This project has therefore been undertaken to develop a flexible design technique that can be used to gain further insight into the nature of a heat exchanger network. The objective of this project was to develop a network design technique that could be used to consistently generate networks that are near optimal. The main feature of the network design technique developed is the application of the optimisation process at two levels. The first level is match optimisation, and the second level is network optimisation. The objective function to be minimised is the total annual cost. The total annual cost is the sum of the annual cost of energy and the annual cost of capital. The annual cost of energy is the sum of the annual costs of hot utilities and cold utilities. The annual cost of capital is the sum of the annual costs of process, hot utility, and cold utility exchangers.
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Mammen, John Joe. "Retrofit of heat exchanger networks of a petroleum refinery crude unit (CDU) using pinch analysis." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/860.
Повний текст джерелаАнотація:
Thesis submitted in fulfilment of the requirements for the degree of Master of Technology: Chemical Engineering, In the Faculty of Engineering,
Cape Peninsula University of Technology
2014Energy efficiency has become an important feature in the design of process plants due to the rising cost of energy and the more stringent environmental regulations being implemented worldwide. In South Africa as in other African countries, most of the chemical plants were built during the era of cheap energy with little emphasis placed on energy efficiency due to the abundance of cheap utility sources such as coal and crude oil. In most of these plants, there exists significant potential for substantial process heat recovery by conceptual integration of the plant’s heat exchangers. Pinch Technology (PT) has been demonstrated to be a simple and very effective technique for heat integration and process optimization. This study applies the PT approach to retrofit the heat exchangers network of the Crude Distillation Unit (CDU), of a complex petroleum refinery with the aim to reduce utilities requirement and the associated gaseous pollutants emission. This objective is accomplished by firstly conducting an energy audit of the unit to scope for potential energy saving. The existing Heat Exchanger Network (HEN) was re-designed using the remaining problem analysis (RPA) to achieve improved process energy recovery while making maximum use of the existing exchangers. The aim is to maintain the existing plant topology as much as possible. This network was later relaxed trading heat recovery with number of heat transfer unit so as to optimize the capital cost. These were implemented in AspenPlus v7.2 environment. The cost implications of the retrofitted and evolved networks including the capital and operating costs were determined on a 5 years payback time basis. The Problem Table (PT) analysis revealed that the minimum utilities requirements are 75 MW and 55 MW for the hot and cold utilities respectively. Compared to the existing utilities requirements of 103 MW for hot utility and 83 MW for cold utility, this represent a potential savings of about 26 % and 33 % savings for the hot and cold utilities respectively. The target utilities usage in the re-designed network after applying Remaining Problem Analysis (RPA) was found to be 55 MW for the cold utility and 75 MW for hot utility. The relaxed HEN required a cold utility of 62.5 MW and hot utility of 81 MW. From the total cost estimation, it was found that, although an energy saving of 34% can be achieved by the re-designed network before relaxation, the capital cost, US$ 1670000 is significantly higher than for the existing network (about US$ 980000). The final relaxed network gave an energy saving of 34% and with total cost of US$ 1100000. It was recommended from the study after cost comparisons of the four different networks (the original network, the MER network, the relaxed network and a grass-root design) that the best network for the retrofit purpose was the relaxed HEN, because there is no major shift in deviation from the topology of the original network. From the analysis it was found that a 34% saving in energy cost could be achieved from this retrofit. The Total Annual Cost (TAC) for this network gives credence to the fact that this retrofit which applied the rules of pinch analysis can bring about real saving in energy usage.
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Ільченко, Марія Володимирівна. "Обґрунтування енергоефективних режимів роботи системи рекуперативних теплообмінників в процесі переробки піроконденсату". Thesis, НТУ "ХПІ", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/32636.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.17.08 – процеси та обладнання хімічної технології. – Національний технічний університет "Харківський політехнічний інститут" Міністерства освіти і науки України, Харків, 2017 р.
Дисертацію присвячено аналізу системи рекуперативного теплообміну і визначенню її недоліків для обґрунтування енергоефективних режимів роботи установки переробки піроконденсату з подальшим удосконаленням тепло- обмінної мережі. Проведено аналіз розвитку методології інтеграції процесів хімічних виробництв. Обґрунтовано необхідність застосування високоефективного пластинчастих теплообмінників на сучасних підприємствах задля максимальної економії енергоресурсів. Розглянуто тепловий розрахунок теплообмінника, принципи визначення середнього температурного напору і коефіцієнтів тепловіддачі. Досліджено можливість застосування відомих моделей перемішування, витіснення та їхньої комбінації при обрахунку теплообмінних апаратів. Наведено алгоритми розрахунку теплообмінників із робочими середовищами, що знаходяться в одній фазі та в різних. Представлено імітаційну модель переробки піроконденсату на установці виробництва бензолу, виконану за допомогою програмного забезпечення UniSim Design. Перевірено взаємне узгодження початкових даних та відзначено високу ступінь збіжності матеріальних і теплових балансів в отриманій розра-хунково-імітаційній моделі. Проведено аналіз функціонуючої теплообмінної системи, встановлено її недоліки та потенціал для енергозбереження. Екстраговано технологічні потоки та розраховано існуючу локалізацію пінчу зі встановленням значення мінімального температурного напору ΔTmin. Визначено локалізацію пінчу для можливої інтеграції. Розроблено три варіанти проектів реконструкції мережі теплообмінних апаратів із власними значеннями ΔTmin. Обчислено можливі техніко-економічні ефекти від запровадження проектів інтеграції у виробництво. Обрано найбільш економічно доцільний варіант проекту реконструкції системи теплообміну та запропоновано комплект теплообмінних апаратів із необхідними технічними характеристиками.Thesis for granting the Degree of Candidate of Technical sciences in specialty 05.17.08 – processes and equipment of chemical technology – National Technical University "Kharkiv Polytechnic Institute" of Ministry of Education and Science of Ukraine, 2017. The thesis is dedicated to the analysis of recuperative heat exchange system and determining its shortcomings for a substantiation of the energy efficient modes on pyrocondensate processing installation with further improvement of heat exchange network. The analysis of process integration methodology for chemical production is made. The necessity of the highly efficient plate heat exchangers for modern enterprises in order to maximize energy savings is substantiated. The thermal calculation of the heat exchanger, the principles of determining the average temperature pressure and the heat transfer coefficients are considered. The algorithms of the heat exchangers calculation with one-phase and two-phase working environments is provided. The simulation model of the process of pyrocondensate processing at the plant for the benzene production, performed using UniSim Design software, is presented. The mutual reconciliation of the initial data is checked and the high degree of material and thermal balances convergence in the resulting calculation-and-imitation model is noted. The analysis of the functioning heat exchange system is carried out, its deficiencies and energy saving potential are established. A number of technological streams are extracted and the existing pinch localization with determining of mini-mum temperature difference value ΔTmin are calculated. The pinch localization for possible process integration is determined. Three variants of reconstruction projects for the heat exchanger network, involved in the pyrocondensate processing, with their own optimum minimum temperature differ-ence values ΔTmin are developed. The most economically feasible variant of the heat exchange system reconstruction project is selected and a set of heat exchangers with the necessary technical characteristics are proposed.
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Santana, Mariana Fraga. "Síntese automática de redes de trocadores de calor a partir de análise Pinch e programação matemática." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266753.
Повний текст джерелаАнотація:
Orientador: Roger Josef ZempDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-20T09:52:33Z (GMT). No. of bitstreams: 1 Santana_MarianaFraga_M.pdf: 1967335 bytes, checksum: 90f67a6bf06f7540d4dea0d84fc080bc (MD5) Previous issue date: 2012
Resumo: Desde a crise energética dos anos 70, a otimização do consumo de energia se tornou uma importante tarefa para os engenheiros de processo. Duas diferentes metodologias têm sido aplicadas para minimizar o uso de energia em processos químicos. A primeira é a metodologia Pinch, que envolve a aplicação de análise termodinâmica do processo e baseia-se em metas de energia e custo para obter uma rede de trocadores de calor que opera com o mínimo consumo de energia. A segunda é a programação matemática, que consiste na elaboração de modelos matemáticos complexos resolvidos através de métodos numéricos. Neste trabalho, uma nova metodologia para a síntese de redes de trocadores de calor é apresentada. O procedimento proposto combina a abordagem sistemática da tecnologia Pinch com métodos de programação matemática (linear inteira mista) e procedimentos evolutivos. A nova metodologia é baseada na otimização de uma superestrutura cuja complexidade varia ao longo do procedimento de síntese da rede de trocadores, e que permite ao engenheiro de projeto a consideração das restrições do processo sem necessidade de formulação matemática das mesmas. Uma vantagem da metodologia é a possibilidade de considerar aspectos práticos como operabilidade e controlabilidade. O método proposto é ilustrado com a integração energética de três problemas típicos: um caso-teste com quatro correntes, o caso padrão em estudos de integração energética da planta simplificada de aromáticos e o caso recente do sistema de célula combustível a membrana trocadora de prótons. Foram obtidas redes alternativas para os casos estudados, que são energeticamente eficientes, mais baratas e simples
Abstract: Since the energy crisis of the 70s, the optimization of energy consumption has become an important task for process engineers. Two different methodologies have been applied to minimize energy use in chemical processes. The first methodology is the pinch method, which involves applying process thermodynamic analysis and it is based on energy and cost targets for a network of heat exchangers operating at the minimum power consumption. The second one is the mathematical programming, which is the development of complex mathematical models solved through numerical methods. In this work, a new methodology for the synthesis of heat exchanger networks is presented. The proposed procedure combines the systematic approach of Pinch technology with mathematical programming methods (mixed integer linear) and evolutionary procedures. The new methodology is based on the optimization of a superstructure whose complexity varies throughout the synthesis procedure of the network of exchangers, which allows the design engineer to consider the constraints of the process without having to include them into the mathematical formulation. One advantage of this methodology is the possibility of considering practical aspects such as controllability and operability. The proposed method is illustrated by the energy integration of three typical problems: a test case with four streams, the standard case in studies of energy integration simplified aromatics plant and the recent case of fuel processor system coupled to proton exchange membrane fuel cell. Alternative networks were obtained for the cases studied, which are energy efficient, cost-effective and simpler
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química
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Prinsloo, Gerto. "Online boiler convective heat exchanger monitoring: a comparison of soft sensing and data-driven approaches." Master's thesis, Faculty of Engineering and the Built Environment, 2018. http://hdl.handle.net/11427/30038.
Повний текст джерелаАнотація:
Online monitoring supports plant reliability and performance management by providing real time information about the condition of equipment. However, the intricate geometries and harsh operating environment of coal fired power plant boilers inhibit the ability to do online measurements of all process related variables. A low-cost alternative lies in the possibility of using knowledge about boiler operation to extract information about its condition from standard online process measurements. This approach is evaluated with the aim of enhancing online condition monitoring of a boiler’s convective pass heat exchanger network by respectively using a soft sensor and a data-driven method. The soft sensor approach is based on a one-dimensional thermofluid process model which takes measurements as inputs and calculates unmeasured variables as outputs. The model is calibrated based on design information. The data-driven method is one developed specifically in this study to identify unique fault signatures in measurement data to detect and quantify changes in unmeasured variables. The fault signatures are initially constructed using the calibrated one-dimensional thermofluid process model. The benefits and limitations of these methods are compared at the hand of a case study boiler. The case study boiler has five convective heat exchanger stages, each composed of four separate legs. The data-driven method estimates the average conduction thermal resistance of individual heat exchanger legs and the flue gas temperature at the inlet to the convective pass. In addition to this, the soft sensor estimates the average fluid variables for individual legs throughout the convective pass and therefore provides information better suited for condition prognosis. The methods are tested using real plant measurements recorded during a period which contained load changes and on-load heat exchanger cleaning events. The cleaning event provides some basis for validating the results because the qualitative changes of some unmeasured monitored variables expected during this event are known. The relative changes detected by both methods are closely correlated. The data-driven method is computationally less expensive and easily implementable across different software platforms once the fault signatures have been obtained. Fault signatures are easily trainable once the model has been developed. The soft sensors require the continuous use of the modelling software and will therefore be subject to licencing constraints. Both methods offer the possibility to enhance the monitoring resolution of modern boilers without the need to install any additional measurements. Implementation of these monitoring frameworks can provide a simple and low-cost contribution to optimized boiler performance and reliability management.