Difference between revisions of "Literature"

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</p><p><b>Download Link:</b> https://unisanta.br/arquivos/mestrado/mecanica/dissertacoes/Dissertacao_Roberto_Paulo.pdf
 
</p><p><b>Download Link:</b> https://unisanta.br/arquivos/mestrado/mecanica/dissertacoes/Dissertacao_Roberto_Paulo.pdf
 
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== Thermal-Numerical Simulation of the Gas Offshore Production Undersea Facilities at the Amistad Field ==
 +
 +
'''Authors:''' Félix Gallo Cruz (Petroleum Department of Escuela Politécnica Nacional) | Andrés Leonardo Sola (Petroleum Department of Escuela Politécnica Nacional) | Joshua Andre Rosero (Petroleum Department of Escuela Politécnica Nacional) | Jaime Oswaldo Gonzalez (Petroleum Department of Escuela Politécnica Nacional)
 +
 +
'''Abstract:''' Thermal numerical simulation of two undersea flowlines of natural gas production at Amistad field was developed in order to avoid non-productive time caused by plugging of solid precipitation; due to the operation conditions and recorded problems during gas production in this field, a complete study of thermodynamics, heat losses and multiphase behavior of the production fluid becomes imperative to prevent and control solid formation and flow blockage.
 +
The thermodynamic behavior of gas was analytically determined based on the thermal and transport properties of fluid phases, beginning with the study of the pressure-temperature diagram of the production fluid to define the type of solids that could precipitate within the flow lines (hydrates). The heat transfer analysis was determined applying two methods, one numerical and one analytical, the numerical by the computational fluid dynamics (CFD) method with the support of the ANSYS-CFX software; and the analytical model obtained from the literature that was used to validate it. The hydrodynamic behavior of multiphase flow and pressure losses were determined by the Beggs & Brill (1973) correlation and were contrasted with the open source DWSIM software tool performance. The overall heat transfer coefficient was determined before continuing with the numerical modeling due to its importance and influence in the CFD simulation, which covers three stages: selection of the most optimum pipeline model, mesh refining, and validation of the developed model for a heat transfer phenomenon in two-phase flow. Once the heat loss model was defined by a steady state simulation, a transient simulation was carried out to calculate the gas cooling time in a case of sudden flow shutdown, considering the standard pipe currently used and three polymers of low thermal conductivity as proposed alternate materials instead of carbon-steel or as or as thermal insulation coatings, as appropriate; these are polypropylene, polyurethane and high density polyethylene. Finally, five analytical correlations of hydrate precipitation obtained from the literature and two software precipitation equilibrium curves were selected to define the precipitation scenarios of the system using the simulation results.
 +
According to the P-T diagram, the only solids that could be precipitated in the steel pipelines are methane hydrates due to the composition of the production fluid and the operating conditions of the wells. The thermal gradient of the flowlines is the most relevant result of the numerical heat transfer analysis, this one shows the critical points of the pipes where the fluid reaches its lowest temperature, that is, the temperature of the underwater current. The critical point from the wellhead for both steel lines is 5560 [ft] according to the resulting thermal gradient, although for the second line, it is actually a bit shorter due to its length limit, 5300 [ft]. From the analysis of pressure and temperature conditions at these points, two scenarios of precipitation were established considering all the equilibrium curves. Then, one of the proposed scenarios confirmed the presence of hydrates in these two production lines of the field, providing a clearer realization of the problem that includes the time, distance and critical conditions of pressure and temperature where precipitation occurs. Subsequently, the three analyzes of heat loss of the other proposed materials were compared with the results of the base case to determine the most effective pipeline configuration to avoid the formation of hydrates and it was concluded that precipitation will not occur throughout the entire flowline if any of the polymers is applied as thermal insulator or pipe material, as appropriate.
 +
In addition, the effects of the hydrodynamic phenomenon caused by the multiphase flow were studied, determining a mist flow pattern, where the liquid phase of the fluid is dispersed within the gaseous phase in the form of small water droplets.
 +
 +
'''Download Link:''' [https://www.onepetro.org/conference-paper/OTC-29751-MS https://www.onepetro.org/conference-paper/OTC-29751-MS]

Latest revision as of 13:28, 4 November 2019

This page lists published scientific and/or technical papers/articles which use or cite DWSIM to some extent.

Technical Papers

Process Simulation Unit Operation Models - Review of Open and HSC Chemistry I/O Interfaces

Author: Marko Leino

Abstract: Chemical process modelling and simulation can be used as a design tool in the development of chemical plants, and is utilized as a means to evaluate different design options. The CAPEOPEN interface standards were developed to allow the deployment and utilization of process modelling components in any compliant process modelling environment. This thesis examines the possibilities provided by the CAPE-OPEN interfaces and the .NET framework to develop compliant, cross-platform process modelling components, particularly unit operations. From the software engineering point of view, a unit operation is a representation of physical equipment, and contains the mathematical model of its functionality. The study indicates that the differences between the CAPE-OPEN standards and Outotec HSC Chemistry Sim are negligible at the conceptual level. On the other hand, at the implementation level, the differences are quite considerable. Regardless of the simulation application being used, the modelling of unit operations requires interdisciplinary skills, and creating tools and methods to ease the development of such models is well justified. The results of this study suggest that CAPE-OPEN both provides various paths to change the way HSC Chemistry Sim works and offers the HSC development team a chance to determine an alternative way to distribute tasks between simulation components. In addition, making HSC Chemistry Sim compliant would bring benefits, such as an extended process modelling component library, and perhaps more publicity. Obviously, the workload required by the changes depends on the chosen path, which invariably entails a lengthy learning curve. This thesis contributes by helping to make that learning curve shorter.

Keywords: CAPE-OPEN, HSC Chemistry Sim, unit operation, process simulation

Download Link: https://dspace.cc.tut.fi/dpub/bitstream/handle/123456789/23943/Leino.pdf?sequence=1

Implementation of a Property Database and Thermodynamic Calculations in OpenModelica for Chemical Process Simulation

Authors: Rahul Jain, Priyam Nayak, Rahul A. S, Pravin Dalve, Kannan M. Moudgalya, P. R. Naren, Daniel Wagner, and Peter Fritzson

Publication: Ind. Eng. Chem. Res., Article ASAP; DOI: 10.1021/acs.iecr.8b05147; Publication Date (Web): February 20, 2019

Abstract: An attempt has been made to enhance the thermodynamic capability of the general purpose modeling and simulation environment OpenModelica. The property database ChemSep and the thermodynamic algorithms of DWSIM are made available in OpenModelica. The following three approaches, listed in the order of increasing computational efficiency, are attempted in this work: Python-C API, socket programming, and a native port. The most efficient method of native port is adopted to make available NRTL, Peng–Robinson, UNIFAC, and UNIQUAC algorithms in OpenModelica. Through several examples, OpenModelica results are compared with Aspen Plus, indicating a good match in all cases. This work is released as an open source to enhance the collaboration among chemical engineers.

Download link: https://pubs.acs.org/doi/abs/10.1021/acs.iecr.8b05147

Development of a Thermodynamic Engine in OpenModelica

Authors: Rahul Jain, Kannan M. Moudgalya, Peter Fritzson, Adrian Pop

Publication: Proceedings of the 12th International Modelica Conference, Prague, Czech Republic, May 15-17, 2017, Volume , Issue 132, 2017-07-04, Pages 89-99, ISSN 1650-3740

Abstract: OpenModelica, an open source equation oriented modeling environment for steady state and dynamic simulation, lacks good chemical engineering support. This problem is addressed by making available in different ways the thermodynamic library Chemsep that comes with DWSIM, an open source sequential modular steady state simulator. Only slow speeds could be achieved through a Python-C API based interface connecting OpenModelica with the thermodynamic library. A socket programming based interface helps achieve faster speeds. Best results have been achieved by porting the thermodynamic library and the calculation routines to OpenModelica, due to two reasons: (1) thermodynamic equations are solved simultaneously with mass and energy balances (2) overheads in calling the external routines of DWSIM are eliminated. Performances of the above mentioned three approaches have been validated with steady state and dynamic simulations. Benzene - toluene separation, methanol - ethanol - water distillation, and steam distillation of an n-octane - n-decane mixture, have been carried out through these simulations. This work makes available a powerful simulation platform to the chemical engineering.

Keywords: OpenModelica DWSIM Chemsep thermodynamics modeling simulation chemical engineering media Python-C API Socket programming

Download Link: http://www.ep.liu.se/ecp/132/009/ecp1713289.pdf

Scientific Papers

Methyl Esters Production by Heterogeneous Catalyst Mixtures of CaO/Nb2O5 with Simulation of Analysis of Environmental Impacts

Authors: Cubides-Román, Diana C., Constantino, André F., David, Geraldo F., Martins, Lucas F., Santos, Reginaldo B. dos, Romão, Wanderson, Cunha Neto, Alvaro, & Lacerda Jr., Valdemar

Publication: Journal of the Brazilian Chemical Society, 30(3), 562-570.

Abstract: The conventional biodiesel process, although it reaches high conversion yields and productivity, faces problems related to the use of homogeneous catalysts. This work aims to study mixtures of calcium oxide (CaO) and niobium oxide (Nb2O5) as the heterogeneous catalyst. It was used a full 23 factorial design with four central points to analyze how the mass percentage of the oxides, the molar ratio of reactants, and the reaction temperature affect the conversion yield to methyl esters. The best conversion yield was found near to 89% using 1.8% of catalyst, a 1:36 oil to methanol ratio and at 77 ºC as reaction temperature. Finally, it was performed a simplified simulation to compare the heterogeneous catalyst process with the conventional process, and an algorithm to compare the effects of the exit streams of each process would have on the environment. The simulations results display a better performance for the heterogeneous catalyst process studied.

Keywords: biodiesel; heterogeneous catalyst; calcium oxide; niobium; process simulation

Download Link: http://dx.doi.org/10.21577/0103-5053.20180204

Model and Simulation of a Hydrotreatment Reactor for Diesel Hydrodesulfurization in Oil Refining

Authors: Jorge Buitrago, Dario Amaya and Olga Ramos

Publication: Contemporary Engineering Sciences, Vol. 10, 2017, no. 25, 1245-1254

Abstract: One of the most developed industries in the world is the industry dedicated to extraction and treatment of crude oil, due to his economic profitability. One of the equipment more important in any process is the reactor, which is the place where the physico-chemical transformations of the matter are carried out. The hydrotreatment process is used in oil refining, to decrease the level of different contaminants in the crude. Usually, this process is applied to the clearance of sulphur in contaminated streams. The process was modeled and simulated through the Open Source DWSIM software, using hydrogen as reactant and Ni-Mo 𝛾𝐴𝑙2𝑂3 as catalyst. As product was obtained acid crude. It was chosen the model Chao Seader to predict the main properties of each compound present in the reactor. Through the reuse of hydrogen in the system, it was possible reach a 0.0093% weight of Sulphur in the final crude stream. Furthermore, it was designed the furnace used to warm up the mixture for the reactor and the cooler used to separate the volatile compounds.

Keywords: Heavy diesel, Chemical reactor, Chemical simulation, DWSIM, Chao Seader model, HDS

Download Link: http://www.m-hikari.com/ces/ces2017/ces25-28-2017/p/amayaCES25-28-2017-1.pdf

Chemical engineering aspects of plasma-assisted CO2 hydrogenation over nickel zeolites under partial vacuum

Authors: Federico Azzolina-Jury, Diogo Bento, Carlos Henriques, Frédéric Thibault-Starzyk

Publication: Journal of CO2 Utilization, Volume 22, 2017, Pages 97-109, ISSN 2212-9820

Abstract: Ni-zeolites (ZSM-11 and USY) were prepared for application in carbon dioxide hydrogenation. Structure, physical properties and texture were analyzed by XRD, N2 sorptiometry, SEM and TEM images. The zeolites nickel reducibility (determined by in-situ TPR-MS) was directly related to the catalytic activity of zeolites. Glow-discharge plasma-assisted CO2 hydrogenation was carried out under partial vacuum using a packed-bed catalytic reactor under two different configurations: In-Plasma Catalysis (IPC) and Post-Plasma Catalysis (PPC). CO2 hydrogenation into CO (CO2+H2→CO+H2O) and CO2 methanation (CO2+4H2→CH4+2H2O) reactions were more efficient when the reaction was assisted by plasma using the IPC mode. In IPC mode, a novel phenomenon was observed: a considerable amount of methane was released from the catalyst after plasma extinction. This phenomenon was explained combining the operando IR plasma technique and the analysis of the carbon balance during the plasma-assisted CO2 hydrogenation reaction. Both configurations (IPC and PPC) were studied under different volumetric flow rates and the minimum lifetime of excited species generated within the plasma discharge for methane production was determined. The lifetime of the more active species which are responsible for methane production was lower than 67ms. Under the operation conditions used in this work, methane production was only possible when CO2 hydrogenation was performed in IPC mode. CO2 hydrogenation was found to be more energy efficient when the reaction was carried out under plasma assistance compared to conventional heating. Higher CO2 conversions, CO and CH4 yields were achieved with respect to conventional heating at lower temperatures when plasma assistance was used.

Keywords: Plasma; Glow discharge; CO2 methanation; Nickel zeolites; operando IR

Download Link: https://doi.org/10.1016/j.jcou.2017.09.017

Techno-Economic Comparison of Onshore and Offshore Underground Coal Gasification End-Product Competitiveness

Authors: Natalie Christine Nakaten, Thomas Kempka

Publication: Energies 2017, 10(10), 1643; doi:10.3390/en10101643 (registering DOI)

Abstract: Underground Coal Gasification (UCG) enables the utilisation of coal reserves that are currently not economically exploitable due to complex geological boundary conditions. Hereby, UCG produces a high-calorific synthesis gas that can be used for generation of electricity, fuels and chemical feedstock. The present study aims to identify economically competitive, site-specific end-use options for onshore and offshore produced UCG synthesis gas, taking into account the capture and storage (CCS) and/or utilisation (CCU) of resulting CO 2 . Modelling results show that boundary conditions that favour electricity, methanol and ammonia production expose low costs for air separation, high synthesis gas calorific values and H 2 /N 2 shares as well as low CO 2 portions of max. 10%. Hereby, a gasification agent ratio of more than 30% oxygen by volume is not favourable from economic and environmental viewpoints. Compared to the costs of an offshore platform with its technical equipment, offshore drilling costs are negligible. Thus, uncertainties related to parameters influenced by drilling costs are also negligible. In summary, techno-economic process modelling results reveal that scenarios with high CO 2 emissions are the most cost-intensive ones, offshore UCG-CCS/CCU costs are twice as high as the onshore ones, and yet all investigated scenarios except from offshore ammonia production are competitive on the European market. View Full-Text

Keywords: Underground Coal Gasification (UCG); economics; Cost of Electricity (COE); techno-economic model; methanol; ammonia; Carbon Capture and Storage (CCS); Carbon Capture and Utilisation (CCU); electricity generation; process simulation

Download Link: http://www.mdpi.com/1996-1073/10/10/1643

Mix-n-match Reservoir Coupling in Integrated Modeling and Optimization

Authors: Silvya Dewi Rahmawati (Petrostreamz AS/ITB) | Mohammad Faizul Hoda (Petrostreamz AS) | Daniel Wagner (CAPE-OPEN) | Arif Kuntadi (Petrostreamz AS)

Abstract: Reservoir Coupling (running multiple reservoir models in a concerted manner) features have been offered by software vendors for some time but with severe limitations. The participating models necessarily use the same vendor simulators and the models are usually limited to black-oil versions. This paper presents an integrated modeling and optimization solution with vendor independent participating simulators. The three reservoir models use simulators from different vendors (SENSOR®, ECLIPSE®, and MORE®). One model uses a black-oil PVT formulation while the other uses compositional PVT. The reservoir with the black-oil PVT model will be post-processed using consistent and accurate black-oil to compositional stream conversions. Stream conversion will utilize split factor tables to convert each phase volumetric rate to component molar rates. The split factors are a function of pressure and phase and are pre-generated simultaneously with the black-oil PVT tables. Streams from a “reduced” compositional PVT reservoir model are post-processed with another set of split factor tables, which are also a function of phase and pressure. This will allow the automated conversion of the reduced (or pseudoized) molar rates to equivalent “process” feed molar rates. The resulting comingled molar rates are delivered to the surface process simulator. An open source process simulator DWSIM® is used to model the common process facility. The sales products (gas, natural gas liquid (NGL), and oil) from the process facility model are priced in an economic model and the final results are in terms of the net present value (NPV). The optimization formulation maximizes the NPV while controlling key operating parameters of the integrated model. The approach presented in this paper can be used for integrated modeling within production sharing contracts where different companies may insist on using different reservoir simulators.

Keywords: reservoir coupling; streamz conversion; integrated model and optimization

Download Link: https://www.onepetro.org/conference-paper/IPTC-17727-MS

Development and Validation of a Thermodynamic Model for Gasification of Tyres

Author: C. Freda

Publication: Journal of Renewable and Alternative Energy Technologies, Volume 2, 2016

Abstract: A gasification model for waste tyres was developed using the commercial software DWSIM. A thermodynamic approach was adopted. The process was simulated by using air as gasifying agent. The effects of equivalence ratio and gasification temperature on the process were investigated. Equivalence ratio was varied between 0 and 1, while gasification temperature was varied between 500 and 900 °C. The model predicts the following outputs of the process: yield of producer gas and char, volumetric composition and heating value of the gas. Validation with results of experimental tests was carried out to emphasize the limits of the model.

Download Link: <a rel="nofollow" class="external free" href="http://ncerd-unn.gov.ng/joraet/index.php/JRAET/article/view/23/15">http://ncerd-unn.gov.ng/joraet/index.php/JRAET/article/view/23/15</a>

Techno-economic optimization of ethanol synthesis from rice-straw supply chains

Authors: Yohanes Kristianto, Liandong Zhu

Title: Techno-economic optimization of ethanol synthesis from rice-straw supply chains, In Energy, 2017, , ISSN 0360-5442

Abstract: The objective of this article is to design and plan sustainable bio-ethanol supply chain. Modeling supply chains that achieve economic, social and environmental feasibility through production, process and energy efficiency is a challenge. Life cycle assessment that is coupled with techno-economic optimization of bio-ethanol supply chain is an alternative solution to achieve sustainability. A simulation of the biomass conversion is used to find process parameters of the conversion technology. The results show that the unified model is capable of minimizing both CO2 emissions and energy and utility consumptions. In addition, the supply chain is capable of contributing to local economy through jobs creation. While the model is quite comprehensive, the future research recommendation on energy integration and global sustainability is proposed.

Keywords: ethanol; LCA; optimization; techno-economic analysis; rice straws; supply chains

Download Link: http://www.sciencedirect.com/science/article/pii/S0360544217315980

Simulação do Processo de Produção de Biodiesel de Óleo de Palma utilizando os softwares Aspen HYSYS e DWSIM

Authors: Machado, Nélio & Costa, Elinéia & Araújo, M.E.. (2015).

Title: SIMULAÇÃO DO PROCESSO DE PRODUÇÃO DE BIODIESEL DE ÓLEO DE PALMA UTILIZANDO OS SOFTWARES ASPEN HYSYS E DWSIM

Abstract: O biodiesel é um combustível definido na literatura como uma mistura de ésteres de ácidos graxos derivados de fontes renováveis, produzido a partir da reação de transesterificação de óleos ou gorduras com um álcool mais comumente metanol ou etanol, gerando como subproduto o glicerol. Após a reação de transesterificação ainda devem ser considerados os processos de separação para a recuperação do excesso de etanol, a separação dos ésteres do glicerol, e a purificação do biodiesel propriamente dito. O uso de simuladores comerciais representam uma ferramenta de fundamental importância para o projeto e otimização de unidades de produção como a do biodiesel, com inúmeros parâmetros importantes a serem definidos. Este trabalho teve como objetivo simular o processo de produção de Biodiesel de óleo de Palma utilizando dois diferentes simuladores de processos (o software comercial Aspen Hysys V8.4 e o software de interface aberta DWSIM V3.3). As simulações foram realizadas sob as mesmas condições operacionais em ambos os simuladores, sendo as plantas de processo constituídas da etapa de produção de ésteres via transesterificação do óleo de palma com etanol, e da etapa de purificação dos ésteres etílicos produzidos. Nas etapas de reação os dois simuladores apresentaram resultados próximos não sendo observadas diferenças significativas. Nas etapas de recuperação do etanol em excesso foram observadas diferenças nos resultados referentes às temperaturas das correntes de fundo das colunas de destilação. Analisando os resultados das duas simulações foi possível observar que a etapa de purificação e refino dos ésteres produzidos fornece resultados diferentes entre os dois simuladores. A simulação realizada com o Aspen Hysys obteve uma corrente de biodiesel majoritariamente composta por éster etílico (96,42%) isenta de Etanol e Glicerol, apresentando ainda tripalmitina (3,55%) e uma quantidade reduzida de água (0,03%); a simulação realizada com o DWSIM apresentou uma corrente de biodiesel composta por éster etílico (aproximadamente 93,19 %), isenta de água, contendo, ainda, etanol (0,16%), glicerol (2,02%) e tripalmitina (4,31%).

Download Link: https://www.researchgate.net/publication/288183538_SIMULACAO_DO_PROCESSO_DE_PRODUCAO_DE_BIODIESEL_DE_OLEO_DE_PALMA_UTILIZANDO_OS_SOFTWARES_ASPEN_HYSYS_E_DWSIM

Simulação de uma planta de produção de biodiesel

Authors: Teixeira, A.C.C.; Pereira, I.M.L.A.; Medeiros, D.; Fernandes, G.A.C.; Coelho, M.G.

Abstract: A utilização de simuladores de processo se mostra eficiente para a análise de processos industriais por tratar de uma ferramenta que além de possibilitar a visualização da planta industrial como um todo, permite também mapear os fatores que interferem diretamente no processo. Nesse contexto, o objetivo desse trabalho é simular a planta de produção de biodiesel, de forma que seja possível obter um maior percentual de biodiesel purificado. Para isso, é utilizado o software DWSIM e considera-se como matéria-prima o Óleo de Palma. Os resultados encontrados mostram que as composições da corrente do biodiesel final foi de 98,20% de éster etílico, etanol (0,05%) e tripalmitina (1,74%). Portanto, a utilização do simulador DWSIM é eficaz para análise deste processo produtivo.

Keywords: Simulação; DWSIM; Biodiesel

Download Link: http://www.abq.org.br/biocom/trabalhos_detalhes,10344.html

Avaliação da Consistência de um Projeto de Amostragem Contínua em Unidade de Processamento de Gás Natural

Author: Roberto Paulo Gomes André

Abstract: Os analisadores de processos são ferramentas importantes para o acompanhamento analítico em diversas indústrias e são aplicáveis às Unidades de Processamento de Gás Natural para monitoração e controle do processo. Esses instrumentos captam amostras e as condicionam para analisá-las de forma contínua. A compatibilização entre as condições físicas da amostra de processo para o analisador é promovida por um sistema de amostragem cujo projeto engloba o dimensionamento de vários itens com diferentes funções. Tal volume de especificações exige a adoção de critérios bem definidos de projeto a fim de mitigar falhas de implantação desses sistemas. O presente trabalho visou consolidar os critérios para o dimensionamento de um sistema de amostragem e avaliar a consistência de um projeto em uma Unidade de Processamento de Gás Natural. Mediante o conhecimento do funcionamento de uma Unidade de Processamento de Gás Natural, da configuração de um sistema de amostragem para análise desse gás e da literatura técnica aplicável, foram elencados os itens de dimensionamento dos componentes para um sistema de amostragem, levando a elaboração de uma lista de verificação de projeto. A avaliação de consistência mostrou haver aspectos na literatura consultada com diferenças significativas de especificações técnicas que podem impactar as definições de projeto. A aplicação da lista de verificação se mostrou eficaz para identificar falhas no projeto estudado neste trabalho, em especial o regime de fluxo, tempo espacial e condicionamento de temperatura. Como resultados, foi possível corrigir o desempenho do sistema, adequando o tempo espacial de 89 min para 1,2 min, eliminar o risco de condensação da amostra no sistema e a redução do consumo de energia de aquecimento de 400 W para 50 W. As correções aplicadas ao sistema tornam viável a medição analítica proposta.

Keywords: Amostragem. Gás natural. Analisadores de processos. Cromatografia.

Download Link: https://unisanta.br/arquivos/mestrado/mecanica/dissertacoes/Dissertacao_Roberto_Paulo.pdf

Thermal-Numerical Simulation of the Gas Offshore Production Undersea Facilities at the Amistad Field

Authors: Félix Gallo Cruz (Petroleum Department of Escuela Politécnica Nacional) | Andrés Leonardo Sola (Petroleum Department of Escuela Politécnica Nacional) | Joshua Andre Rosero (Petroleum Department of Escuela Politécnica Nacional) | Jaime Oswaldo Gonzalez (Petroleum Department of Escuela Politécnica Nacional)

Abstract: Thermal numerical simulation of two undersea flowlines of natural gas production at Amistad field was developed in order to avoid non-productive time caused by plugging of solid precipitation; due to the operation conditions and recorded problems during gas production in this field, a complete study of thermodynamics, heat losses and multiphase behavior of the production fluid becomes imperative to prevent and control solid formation and flow blockage. The thermodynamic behavior of gas was analytically determined based on the thermal and transport properties of fluid phases, beginning with the study of the pressure-temperature diagram of the production fluid to define the type of solids that could precipitate within the flow lines (hydrates). The heat transfer analysis was determined applying two methods, one numerical and one analytical, the numerical by the computational fluid dynamics (CFD) method with the support of the ANSYS-CFX software; and the analytical model obtained from the literature that was used to validate it. The hydrodynamic behavior of multiphase flow and pressure losses were determined by the Beggs & Brill (1973) correlation and were contrasted with the open source DWSIM software tool performance. The overall heat transfer coefficient was determined before continuing with the numerical modeling due to its importance and influence in the CFD simulation, which covers three stages: selection of the most optimum pipeline model, mesh refining, and validation of the developed model for a heat transfer phenomenon in two-phase flow. Once the heat loss model was defined by a steady state simulation, a transient simulation was carried out to calculate the gas cooling time in a case of sudden flow shutdown, considering the standard pipe currently used and three polymers of low thermal conductivity as proposed alternate materials instead of carbon-steel or as or as thermal insulation coatings, as appropriate; these are polypropylene, polyurethane and high density polyethylene. Finally, five analytical correlations of hydrate precipitation obtained from the literature and two software precipitation equilibrium curves were selected to define the precipitation scenarios of the system using the simulation results. According to the P-T diagram, the only solids that could be precipitated in the steel pipelines are methane hydrates due to the composition of the production fluid and the operating conditions of the wells. The thermal gradient of the flowlines is the most relevant result of the numerical heat transfer analysis, this one shows the critical points of the pipes where the fluid reaches its lowest temperature, that is, the temperature of the underwater current. The critical point from the wellhead for both steel lines is 5560 [ft] according to the resulting thermal gradient, although for the second line, it is actually a bit shorter due to its length limit, 5300 [ft]. From the analysis of pressure and temperature conditions at these points, two scenarios of precipitation were established considering all the equilibrium curves. Then, one of the proposed scenarios confirmed the presence of hydrates in these two production lines of the field, providing a clearer realization of the problem that includes the time, distance and critical conditions of pressure and temperature where precipitation occurs. Subsequently, the three analyzes of heat loss of the other proposed materials were compared with the results of the base case to determine the most effective pipeline configuration to avoid the formation of hydrates and it was concluded that precipitation will not occur throughout the entire flowline if any of the polymers is applied as thermal insulator or pipe material, as appropriate. In addition, the effects of the hydrodynamic phenomenon caused by the multiphase flow were studied, determining a mist flow pattern, where the liquid phase of the fluid is dispersed within the gaseous phase in the form of small water droplets.

Download Link: https://www.onepetro.org/conference-paper/OTC-29751-MS


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