References of "Heyen, Georges"
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See detailLarge-scale synthesis of multi-walled carbon nanotubes in a continuous inclined mobile-bed rotating reactor by the catalytic chemical vapour deposition process using methane as carbon source
Douven, Sigrid ULg; Pirard, Sophie ULg; Chan, Fang-Yue et al

in Chemical Engineering Journal (2012)

Multi-walled carbon nanotubes (CNTs) were produced in a continuous inclined mobile-bed rotating reactor by the catalytic chemical vapour deposition of methane on a bimetallic Ni-Mo/MgO catalyst whose ... [more ▼]

Multi-walled carbon nanotubes (CNTs) were produced in a continuous inclined mobile-bed rotating reactor by the catalytic chemical vapour deposition of methane on a bimetallic Ni-Mo/MgO catalyst whose activity remains constant in the course of time. Measurements performed on the continuous reactor were validated to ensure that the installation worked correctly and that measurements were precise enough. The performance of the reactor was simulated using a model based on the chemical reactor engineering approach. Hypotheses of the model were verified, and a kinetic study was performed to obtain a kinetic rate expression and to determine the catalytic activity as a function of time. The purity level of produced CNTs depends on the desired properties of the product, so the operating conditions are linked to the purity level that is required. A minimal purity level corresponds to high carbon production, and a maximal purity level corresponds to high specific productivity. It was shown that operating conditions had to be fixed to reach a given specific productivity or a given carbon production, and the optimized operating conditions leading to those two opposite purity level objectives were established. [less ▲]

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See detailComparison of Machine Learning techniques for atmospheric pollutant monitoring in a Kraft pulp mill
Sainlez, Matthieu ULg; Heyen, Georges ULg

Conference (2011, November)

In this paper, machine learning techniques are compared to predict nitrogen oxide (NOx) pollutant emission from the recovery boiler of a Kraft pulp mill. Starting from a large database of raw process data ... [more ▼]

In this paper, machine learning techniques are compared to predict nitrogen oxide (NOx) pollutant emission from the recovery boiler of a Kraft pulp mill. Starting from a large database of raw process data related to a Kraft recovery boiler, we consider a regression problem in which we are trying to predict the value of a continuous variable. Generalization is done on the worst case configuration possible to make sure the model is adequate: the training period concerns stationary operations while test periods mainly focus on NOx emissions during transient operations. This comparison involves neural network techniques (i.e., static multilayer perceptron and dynamic NARX network), tree-based methods and multiple linear regression. We illustrate the potential of a dynamic neural approach compared to the others in this prediction task. [less ▲]

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See detailModeling post-combustion CO2 capture with amine solvents
Léonard, Grégoire ULg; Heyen, Georges ULg

Poster (2011, June)

Carbon capture and storage is a technology that can contribute to face the challenge of rising energy demand combined with a growing environmental awareness. In the present work, the CO2 capture process ... [more ▼]

Carbon capture and storage is a technology that can contribute to face the challenge of rising energy demand combined with a growing environmental awareness. In the present work, the CO2 capture process with monoethanolamine (MEA) is modeled using the simulation tool Aspen Plus. Two different modeling approaches are studied and compared: the equilibrium and the rate-based approaches. An optimization of key process parameters is performed and process modifications are studied with the objective of improving the global process energy efficiency. [less ▲]

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See detailKraft RB : recurrent neural network prediction of steam production
Sainlez, Matthieu ULg; Heyen, Georges ULg

Poster (2011, May 30)

In this study, neural networks approaches are compared for predicting the high pressure (HP) steam flow rate from a Kraft recovery boiler. We apply two types of neural networks: a static multilayer ... [more ▼]

In this study, neural networks approaches are compared for predicting the high pressure (HP) steam flow rate from a Kraft recovery boiler. We apply two types of neural networks: a static multilayer perceptron and a dynamic Elman’s recurrent neural network. Starting from a one-day database of raw process data related to the boiler, the goal is to model and predict the next 12-hours of HP steam flow production from the boiler to the steam turbine. The results illustrate the potential of the dynamic approach in this task. [less ▲]

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See detailSupervised learning for a Kraft recovery boiler: a data mining approach with Random Forests.
Sainlez, Matthieu ULg; Heyen, Georges ULg; Lafourcade, Sébastien

in Favrat, Daniel; Maréchal, François (Eds.) ECOS 2010 Volume IV (Power plants and Industrial processes) (2011, January 01)

A data mining methodology, the random forests, is applied to predict high pressure steam production from the recovery boiler of a Kraft pulping process. Starting from a large database of raw process data ... [more ▼]

A data mining methodology, the random forests, is applied to predict high pressure steam production from the recovery boiler of a Kraft pulping process. Starting from a large database of raw process data, the goal is to identify the input variables that explain the most significant output variations and to predict the high pressure steam flow. [less ▲]

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See detailLiquid oxygen compatibility of materials for space propulsion needs
Bozet, Jean-Luc ULg; Heyen, Georges ULg; Dodet, Claude ULg et al

in 4TH EUROPEAN CONFERENCE FOR AEROSPACE SCIENCES (EUCASS) (2011)

Since the origin, the use of liquid oxygen as oxidizer is widespread in space propulsion. It has been the source of numerous incidents. Many materials can burn violently in an oxygen enriched environment ... [more ▼]

Since the origin, the use of liquid oxygen as oxidizer is widespread in space propulsion. It has been the source of numerous incidents. Many materials can burn violently in an oxygen enriched environment when ignited. Consequently, it is mandatory to perform oxygen compatibility tests. In the present work, compatibility tests are impact tests and auto ignition tests. Both standardized test methods are illustrated by test results on polymeric materials (i.e. fluorinated resins, polyimides, polyetherketone) for seals and ball bearing cage. For future needs, in order to face the increase of pressure of injection of propellants in cryogenic engines, the adiabatic compression test has been identified as well suited for qualifying materials as oxygen compatible in highly constraining conditions. Details on the test procedure and on the installation available at the Université de Liège are presented. [less ▲]

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See detailModeling post-combustion CO2 capture with amine solvents
Léonard, Grégoire ULg; Heyen, Georges ULg

in Computer Aided Chemical Engineering (2011), 29

Carbon capture and storage is a technology that can contribute to face the challenge of rising energy demand combined with a growing environmental awareness. In the present work, the CO2 capture process ... [more ▼]

Carbon capture and storage is a technology that can contribute to face the challenge of rising energy demand combined with a growing environmental awareness. In the present work, the CO2 capture process with monoethanolamine (MEA) is modeled using the simulation tool Aspen Plus. Two different modeling approaches are studied and compared: the equilibrium and the rate-based approaches. An optimization of key process parameters is performed and process modifications are studied with the objective of improving the global process energy efficiency. [less ▲]

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See detailExperimental procedure and statistical data treatment for the kinetic study of selective hydrodechlorination of 1,2-dichloroethane into ethylene over a Pd-Ag sol–gel catalyst
Pirard, Sophie ULg; Pirard, Jean-Paul ULg; Heyen, Georges ULg et al

in Chemical Engineering Journal (2011), 173(3), 801-812

The kinetics of selective hydrodechlorination of 1,2-dichloroethane into ethylene over a Pd- Ag/SiO2 catalyst was studied using an a priori experimental design with five independent variables—temperature ... [more ▼]

The kinetics of selective hydrodechlorination of 1,2-dichloroethane into ethylene over a Pd- Ag/SiO2 catalyst was studied using an a priori experimental design with five independent variables—temperature and partial pressures of 1,2-dichloroethane, hydrogen, ethylene and hydrogen chloride. A Langmuir–Hinshelwood model including two types of active site and the 1,2-dichloroethane adsorption as the rate-determining step was found to fit correctly with experimental data, according to the analysis of variance and the analysis of pondered residuals. The study allowed for catalytic deactivation. The rigorous experimental and statistical approach followed to carry out such a kinetic study is explained in detail. [less ▲]

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See detailOptimisation du procédé de captage de CO2 dans des solvants aminés
Léonard, Grégoire ULg; Heyen, Georges ULg

in Récents Progrès en Génie des Procédés (2011), 101

Post-combustion carbon capture in amine solvents is currently one of the most promising technologies to prevent large quantities of CO2 from being emitted into the atmosphere. Two models (equilibrium and ... [more ▼]

Post-combustion carbon capture in amine solvents is currently one of the most promising technologies to prevent large quantities of CO2 from being emitted into the atmosphere. Two models (equilibrium and kinetics) have been built using the Aspen Plus software in order to optimise the capture process. A sensitivity study at constant CO2 capture rate has shown that the solvent concentration, its flow rate and its regenerating pressure have the largest influence on the process energy requirement. Different process flowsheet modifications such as the lean vapor compression, an absorber inter-cooling and the split-flow configuration have been simulated as well, decreasing the energy cost of the process. Tests on a pilot installation will be made that will help to validate this model. [less ▲]

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See detailRecurrent neural network prediction of steam production in a Kraft recovery boiler
Sainlez, Matthieu ULg; Heyen, Georges ULg

in Pistikopoulos, E. N.; Georgiadis, M. C.; Kokossis, A. C. (Eds.) 21st European Symposium on Computer Aided Process Engineering (Part B) (2011)

In this paper, neural networks approaches are compared for predicting the high pressure (HP) steam flow rate from a Kraft recovery boiler. We apply two types of neural networks: a static multilayer ... [more ▼]

In this paper, neural networks approaches are compared for predicting the high pressure (HP) steam flow rate from a Kraft recovery boiler. We apply two types of neural networks: a static multilayer perceptron and a dynamic Elman’s recurrent neural network. Starting from a one-day database of raw process data related to the boiler, the goal is to model and predict the next 12-hours of HP steam flow production from the boiler to the steam turbine. The results illustrate the potential of the dynamic approach in this task. [less ▲]

Detailed reference viewed: 36 (7 ULg)
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See detailSupervised learning for a Kraft recovery boiler: a data mining approach with Random Forests.
Sainlez, Matthieu ULg; Heyen, Georges ULg; Lafourcade, Sébastien

Conference (2010, June)

A data mining methodology, the random forests, is applied to predict high pressure steam production from the recovery boiler of a Kraft pulping process. Starting from a large database of raw process data ... [more ▼]

A data mining methodology, the random forests, is applied to predict high pressure steam production from the recovery boiler of a Kraft pulping process. Starting from a large database of raw process data, the goal is to identify the input variables that explain the most significant output variations and to predict the high pressure steam flow. [less ▲]

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See detailModeling post-combustion CO2 capture with amine solvents
Léonard, Grégoire ULg; Heyen, Georges ULg

Conference (2010)

Oral communication at the Cape-forum, Aachen, 2010. Modeling CO2 capture process and optimization of some process parameters with an equilibrium-based model.

Detailed reference viewed: 39 (6 ULg)
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See detailModeling post-combustion CO2 capture with amine solvents
Léonard, Grégoire ULg; Heyen, Georges ULg

Poster (2010)

In order to avoid the emission of large amounts of greenhouse gas, CO2 capture in fossil fuel power plants and subsequent underground CO2 sequestration is studied. The capture occurs by reactive CO2 ... [more ▼]

In order to avoid the emission of large amounts of greenhouse gas, CO2 capture in fossil fuel power plants and subsequent underground CO2 sequestration is studied. The capture occurs by reactive CO2 absorption into chemical solvent systems at moderate temperature (~50°C) followed by solvent regeneration at higher temperature (~120°C). So far, the most employed solvent for acid gas capture is monoethanolamine (MEA). One main drawback of this technology is the high energy consumption necessary to regenerate the solvent. In the present work, the CO2 capture process with MEA is modeled using the simulation tool Aspen Plus®. The base case process is optimized and some process improvements are studied that imply a significant decrease of the process exergy consumption. [less ▲]

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See detailQuantitative study of catalytic activity and catalytic deactivation of Fe–Co/Al2O3 catalysts for multi-walled carbon nanotube synthesis by the CCVD process
Pirard, Sophie ULg; Heyen, Georges ULg; Pirard, Jean-Paul ULg

in Applied Catalysis A : General (2010), 382

The catalytic deactivation during multi-walled carbon nanotube (MWNT) synthesis by the CCVD process and the influence of hydrogen on it were quantified. Initial specific reaction rate, relative specific ... [more ▼]

The catalytic deactivation during multi-walled carbon nanotube (MWNT) synthesis by the CCVD process and the influence of hydrogen on it were quantified. Initial specific reaction rate, relative specific productivity and catalytic deactivation were studied. Carbon source was ethylene, and a bimetallic iron–cobalt catalyst supported on alumina was used. The catalytic deactivation was modeled by a decreasing hyperbolic law, reflecting the progressive accumulation of amorphous carbon on active sites. While the initial specific reaction rate was found not to be influenced by hydrogen, catalytic deactivation was found to be modified in the presence of hydrogen, which delayed and slowed down the deactivation by avoiding amorphous carbon deposition, thus leading to a greater relative specific productivity of carbon nanotubes. [less ▲]

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See detailPerformance monitoring of an industrial boiler: classification of relevant variables with Random Forests
Sainlez, Matthieu ULg; Heyen, Georges ULg

in Pierucci, Sauro; Ferraris, Guido Buzzi (Eds.) 20th European Symposium on Computer Aided Process Engineering – ESCAPE20 (2010)

A data mining methodology, the random forests, is applied to analyze pollutant emission from the recovery boiler of a Kraft pulping process. Starting from a large database of raw process data, the goal is ... [more ▼]

A data mining methodology, the random forests, is applied to analyze pollutant emission from the recovery boiler of a Kraft pulping process. Starting from a large database of raw process data, the goal is to identify the input variables that explain the most output variations. [less ▲]

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See detailAdaptation and testing of data reconciliation software for CAPE-OPEN compliance
Radermecker, Eric; Dumont, Marie-Noëlle ULg; Heyen, Georges ULg

in Computer Aided Chemical Engineering (2009), 26

The experience gained in the development of a CAPE-OPEN 1.0 thermo socket for the BELSIM-VALI software is presented. A material object has been developed and interfaced with the modelling code. The user ... [more ▼]

The experience gained in the development of a CAPE-OPEN 1.0 thermo socket for the BELSIM-VALI software is presented. A material object has been developed and interfaced with the modelling code. The user interface has been adapted. Several case studies were analysed, with performance comparison between the native thermodynamic model, and properties obtained from several CAPE-OPEN thermo plugs. [less ▲]

Detailed reference viewed: 65 (17 ULg)