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Guy Marin - One of the best experts on this subject based on the ideXlab platform.
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Sustainable innovations in Steam Cracking: CO2 neutral olefin production
Reaction Chemistry and Engineering, 2020Co-Authors: Ismaël Amghizar, Guy Marin, Jens Dedeyne, David J. Brown, Kevin Van GeemAbstract:Steam Cracking of hydrocarbons is and will continue to be the main industrial process to produce light olefins in the coming decades. In state of the art Steam Cracking plants more than 90% of the CO2 emissions can be directly related to the high energy consumption of the endothermic conversion in the Cracking furnaces. Steam Cracking accounts for a global emission of more than to 300 million tonnes of CO2per annum. Enhancing heat transfer in the radiation section, using green energy and reducing coke formation are key to substantially reduce CO2 emissions. Heat transfer can be increased by implementing three-dimensional (3D) coil technologies such as swirled and dimpled tubes. These reactor technologies also reduces coke formation because of the lower wall temperatures that are consequently obtained. Advanced manufacturing techniques and better computational abilities have opened the door to novel and improved 3D reactor technologies that are designed to increase the heat transfer while minimizing the pressure drop penalty. At the same time applying high emissivity coatings on the furnace refractory and reactor tubes can further reduce CO2 emissions. Substantial fuel savings can also be obtained by a novel furnace design, where the heat recovery scheme is substantially modified. Combining all these technologies could result in reducing emissions by 30%. Shifting completely to green electricity, which is practically infeasible today, is another alternative but the technologies that would potentially allow this are still in their infancy. These new technologies, combined with advanced process innovations and CO2 capture, will help the industry to meet future emissions targets.
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Crude to olefins: effect of feedstock composition on coke formation in a bench-scale Steam Cracking furnace
Industrial & Engineering Chemistry Research, 2020Co-Authors: Moreno Geerts, Nenad Ristic, Marko Djokic, Guy Marin, Syam Ukkandath Aravindakshan, Kevin Van GeemAbstract:A novel experimental unit has been designed, allowing the examination of the fouling tendency in all relevant sections of a Steam Cracking furnace, that is, dry feed preheater (DFP), dilute feed pr...
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dynamic simulation of fouling in Steam Cracking reactors using cfd
Chemical Engineering Journal, 2017Co-Authors: Laurien Vandewalle, Kevin Van Geem, Jens Dedeyne, David Van Cauwenberge, Guy MarinAbstract:Recently computational fluid dynamics (CFD) has been successfully applied for the evaluation of the start-of-run performance of three-dimensional (3D) coil geometries in Steam Cracking reactors. However, determining the full economic potential of a coil involves tracking its performance throughout the run and not only at start-of-run. Therefore in this work a novel method has been developed that allows to assess the most debated characteristic of these 3D coil geometries, i.e. the potential extension of the run length in combination with the evolution of the product yields during the time on stream. An algorithm based on dynamic mesh generation is presented for simulating coke formation in 3D Steam Cracking reactor geometries, tracking the apparent geometry deformation caused by the growing coke layer. As a proof-of-concept, a Millisecond propane cracker is simulated over the first days of its run length, and this for three different coil designs: a bare tube, a finned tube and a continuously ribbed reactor design. Our simulations show that the ribbed reactors overall outperform the others although in these enhanced tubular geometries the growth of the coke layer is far from uniform. Because of this, the reactor geometry will change over time, which will in turn influence the fluid dynamics, product yields and successive coke formation substantially.
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Optimization of the in Situ Pretreatment of High Temperature Ni–Cr Alloys for Ethane Steam Cracking
Industrial & Engineering Chemistry Research, 2017Co-Authors: Stamatis A. Sarris, Marie Françoise Reyniers, Guy Marin, Natalia Olahova, Kim Verbeken, Kevin Van GeemAbstract:Coke inhibition of reactor materials is one of the major research areas in the field of Steam Cracking. Selecting the optimal in situ pretreatment of a Steam Cracking coil depends on many different aspects such as the reactor material composition, the process conditions, the pretreatment duration, the atmosphere, and the used additives. Therefore, the effect of eight different pretreatments on the coking resistance of a classical Ni/Cr 35/25 high temperature alloy is evaluated in a thermogravimetric setup with a jet stirred reactor under industrially relevant ethane Steam Cracking conditions (dilution 0.33 kg H2O/kg C2H6, continuous addition of 41 ppmw S/HC at T = 1160 K, equivalent ethane conversion 68%). Next to the sequence of the preoxidation and Steam pretreatment, also presulfiding was evaluated. The coking results proved that a high temperature preoxidation, followed by a Steam/air pretreatment at 1173 K for a duration of 15 min, has the best coking performance under ethane Cracking conditions. Thi...
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necessity and feasibility of 3d simulations of Steam Cracking reactors
Industrial & Engineering Chemistry Research, 2015Co-Authors: Pieter Reyniers, Kevin Van Geem, Carl Schietekat, Laurien Vandewalle, David Van Cauwenberge, Guy MarinAbstract:Using detailed kinetic models in computational fluid dynamics (CFD) simulations is extremely challenging because of the large number of species that need to be considered and the stiffness of the associated set of differential equations. The high computational cost associated with using a detailed kinetic network in CFD simulations is why one-dimensional simulations are still used, although this leads to substantial differences compared to reference three-dimensional simulations. Therefore, a methodology was developed that allows one to use detailed single-event microkinetic models in CFD simulations by on the fly application of the pseudo-steady-state assumption to the radical reaction intermediates. Depending on the reaction model size, a speedup factor of more than 50 was obtained compared to the standard ANSYS Fluent routines without losing accuracy. As proof of concept, propane Steam Cracking in a conventional bare reactor and a helicoidally finned reactor was simulated using a reaction model contain...
Kevin Van Geem - One of the best experts on this subject based on the ideXlab platform.
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Sustainable innovations in Steam Cracking: CO2 neutral olefin production
Reaction Chemistry and Engineering, 2020Co-Authors: Ismaël Amghizar, Guy Marin, Jens Dedeyne, David J. Brown, Kevin Van GeemAbstract:Steam Cracking of hydrocarbons is and will continue to be the main industrial process to produce light olefins in the coming decades. In state of the art Steam Cracking plants more than 90% of the CO2 emissions can be directly related to the high energy consumption of the endothermic conversion in the Cracking furnaces. Steam Cracking accounts for a global emission of more than to 300 million tonnes of CO2per annum. Enhancing heat transfer in the radiation section, using green energy and reducing coke formation are key to substantially reduce CO2 emissions. Heat transfer can be increased by implementing three-dimensional (3D) coil technologies such as swirled and dimpled tubes. These reactor technologies also reduces coke formation because of the lower wall temperatures that are consequently obtained. Advanced manufacturing techniques and better computational abilities have opened the door to novel and improved 3D reactor technologies that are designed to increase the heat transfer while minimizing the pressure drop penalty. At the same time applying high emissivity coatings on the furnace refractory and reactor tubes can further reduce CO2 emissions. Substantial fuel savings can also be obtained by a novel furnace design, where the heat recovery scheme is substantially modified. Combining all these technologies could result in reducing emissions by 30%. Shifting completely to green electricity, which is practically infeasible today, is another alternative but the technologies that would potentially allow this are still in their infancy. These new technologies, combined with advanced process innovations and CO2 capture, will help the industry to meet future emissions targets.
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Crude to olefins: effect of feedstock composition on coke formation in a bench-scale Steam Cracking furnace
Industrial & Engineering Chemistry Research, 2020Co-Authors: Moreno Geerts, Nenad Ristic, Marko Djokic, Guy Marin, Syam Ukkandath Aravindakshan, Kevin Van GeemAbstract:A novel experimental unit has been designed, allowing the examination of the fouling tendency in all relevant sections of a Steam Cracking furnace, that is, dry feed preheater (DFP), dilute feed pr...
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pyrometer based control of a Steam Cracking furnace
Chemical Engineering Research & Design, 2020Co-Authors: Stijn Vangaever, Nenad Ristic, Pieter Reyniers, Steffen H Symoens, Marko Djokic, Guy B Marin, Kevin Van GeemAbstract:Abstract Optical thermometry offers great precision, repeatability, flexibility, and stability, hence providing performance advantages in non-contact temperature measurement. To assess its potential for controlling the temperature of Steam Cracking furnaces, ethane Steam Cracking experiments were carried out on pilot plant scale. The control performance of the pyrometer was found to be comparable to that of a weld-on type K thermocouple, the latter being representative of the industrial standard. The tested optical thermometer is suited as a sensor to measure tube metal temperatures of a Steam Cracking reactor coil, either inside or outside of the firebox. Due to its fast response time, optical thermometer temperature measurements help to prevent temperature overshoots, which have an adverse effect on the tube longevity and coke formation. Flexibility in positioning makes optical thermometry a viable alternative compared to conventional type K thermocouples.
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Evaluation of a Ti–Base Alloy as Steam Cracking Reactor Material
Materials, 2019Co-Authors: Stamatis A. Sarris, Marie Françoise Reyniers, Kim Verbeken, Kevin Van GeemAbstract:Low-coking reactor material technologies are key for improving the performance and sustainability of Steam crackers. In an attempt to appraise the coking performance of an alternative Ti–base alloy during ethane Steam Cracking, an experimental study was performed in a jet stirred reactor under industrially relevant conditions using thermogravimetry (Tgasphase = 1173 K, Ptot = 0.1 MPa, XC2H6 = 70%, and dilution δ = 0.33 kgH2O/kgHC). Initially, a typical pretreatment used for Fe–Ni–Cr alloys was utilized and compared with a pretreatment at increased temperature, aiming at better surface oxidation and thus suppressing coke formation. The results revealed a decrease in coking rates upon high temperature pretreatment of the Ti–base alloy, however, its coking performance was significantly worse compared to the typically used Fe–Ni–Cr alloys, and carbon oxides formation increased by a factor of 30 or more. Moreover, the analyzed coupons showed crack propagation after coking/decoking and cooling down to ambient temperature. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy indicated that the prompt and unsystematic oxidation of the surface and bulk caused observable crack initiation and propagation due to alloy brittleness. Hence, the tested Ti–base alloy cannot be considered an industrially noteworthy Steam Cracking reactor alloy.
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CoatAlloy ™ Barrier Coating for Reduced Coke Formation in Steam Cracking Reactors: Experimental Validation and Simulations
Industrial & Engineering Chemistry Research, 2018Co-Authors: Natalia Olahova, Marie Françoise Reyniers, Nenad Ristic, Steffen H Symoens, Marko Djokic, Stamatis A. Sarris, Mathieu Couvrat, Fanny Riallant, Hugues Chasselin, Kevin Van GeemAbstract:The coking tendency under Steam Cracking conditions of CoatAlloy, a newly developed multilayered Al barrier coating deposited on a commercial 25/35 Cr–Ni base alloy and aimed at reducing the coke formation under hydrocarbon atmosphere at >1100 K temperatures was investigated. It was benchmarked to the uncoated commercial 25/35 Cr–Ni base alloy with a known low coking tendency in ethane Steam Cracking in a pilot plant. The influence of process conditions, such as coil outlet temperature, presulfidation, continuous sulfur addition and aging was evaluated. The applied coating resulted in a reduced coking tendency as well as reduced yields of both CO and CO2 compared to the uncoated coil. The surface of both tested reactor materials was studied by means of SEM and EDX analysis. Further scale up was assessed by simulations of an industrial ethane cracker. All the findings show that the CoatAlloy barrier coating is capable of reducing coke formation and maintains its anticoking activity over multiple Cracking–d...
Marie Françoise Reyniers - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of a Ti–Base Alloy as Steam Cracking Reactor Material
Materials, 2019Co-Authors: Stamatis A. Sarris, Marie Françoise Reyniers, Kim Verbeken, Kevin Van GeemAbstract:Low-coking reactor material technologies are key for improving the performance and sustainability of Steam crackers. In an attempt to appraise the coking performance of an alternative Ti–base alloy during ethane Steam Cracking, an experimental study was performed in a jet stirred reactor under industrially relevant conditions using thermogravimetry (Tgasphase = 1173 K, Ptot = 0.1 MPa, XC2H6 = 70%, and dilution δ = 0.33 kgH2O/kgHC). Initially, a typical pretreatment used for Fe–Ni–Cr alloys was utilized and compared with a pretreatment at increased temperature, aiming at better surface oxidation and thus suppressing coke formation. The results revealed a decrease in coking rates upon high temperature pretreatment of the Ti–base alloy, however, its coking performance was significantly worse compared to the typically used Fe–Ni–Cr alloys, and carbon oxides formation increased by a factor of 30 or more. Moreover, the analyzed coupons showed crack propagation after coking/decoking and cooling down to ambient temperature. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy indicated that the prompt and unsystematic oxidation of the surface and bulk caused observable crack initiation and propagation due to alloy brittleness. Hence, the tested Ti–base alloy cannot be considered an industrially noteworthy Steam Cracking reactor alloy.
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CoatAlloy ™ Barrier Coating for Reduced Coke Formation in Steam Cracking Reactors: Experimental Validation and Simulations
Industrial & Engineering Chemistry Research, 2018Co-Authors: Natalia Olahova, Marie Françoise Reyniers, Nenad Ristic, Steffen H Symoens, Marko Djokic, Stamatis A. Sarris, Mathieu Couvrat, Fanny Riallant, Hugues Chasselin, Kevin Van GeemAbstract:The coking tendency under Steam Cracking conditions of CoatAlloy, a newly developed multilayered Al barrier coating deposited on a commercial 25/35 Cr–Ni base alloy and aimed at reducing the coke formation under hydrocarbon atmosphere at >1100 K temperatures was investigated. It was benchmarked to the uncoated commercial 25/35 Cr–Ni base alloy with a known low coking tendency in ethane Steam Cracking in a pilot plant. The influence of process conditions, such as coil outlet temperature, presulfidation, continuous sulfur addition and aging was evaluated. The applied coating resulted in a reduced coking tendency as well as reduced yields of both CO and CO2 compared to the uncoated coil. The surface of both tested reactor materials was studied by means of SEM and EDX analysis. Further scale up was assessed by simulations of an industrial ethane cracker. All the findings show that the CoatAlloy barrier coating is capable of reducing coke formation and maintains its anticoking activity over multiple Cracking–d...
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Impact of Initial Surface Roughness and Aging on Coke Formation during Ethane Steam Cracking
Industrial & Engineering Chemistry Research, 2017Co-Authors: Stamatis A. Sarris, Marie Françoise Reyniers, Steffen H Symoens, Guy B Marin, Natalia Olahova, Kim Verbeken, Kevin Van GeemAbstract:Alloys composition and morphology of the inner wall of Steam Cracking reactors are well-known key factors that affect their substantial coking tendency. The effect of surface roughness on the coking tendency remains uncharted so far and has been studied here for a 35/25 Ni/Cr wt % alloy in a quartz jet stirred reactor equipped with an electro-balance, under coil outlet industrially relevant ethane Steam Cracking conditions: Tgas phase = 1173 K, Ptot = 0.1 MPa and XC2H6 = 70 %. Up to 6 times higher initial coking rates have been observed during cyclic aging in an Rα surface roughness range of 0.15 - 7 μm and cyclic aging proved to have an effect mainly on the catalytic coking behavior. No effect was observed on the asymptotic coking rates. Scanning electron microscopy and energy diffractive X-ray surface analysis and cross-section elemental mappings suggest that the effect of surface roughness and aging on the catalytic coking rate derives mainly from changes in the metal surface composition. The amounts o...
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Optimization of the in Situ Pretreatment of High Temperature Ni–Cr Alloys for Ethane Steam Cracking
Industrial & Engineering Chemistry Research, 2017Co-Authors: Stamatis A. Sarris, Marie Françoise Reyniers, Guy Marin, Natalia Olahova, Kim Verbeken, Kevin Van GeemAbstract:Coke inhibition of reactor materials is one of the major research areas in the field of Steam Cracking. Selecting the optimal in situ pretreatment of a Steam Cracking coil depends on many different aspects such as the reactor material composition, the process conditions, the pretreatment duration, the atmosphere, and the used additives. Therefore, the effect of eight different pretreatments on the coking resistance of a classical Ni/Cr 35/25 high temperature alloy is evaluated in a thermogravimetric setup with a jet stirred reactor under industrially relevant ethane Steam Cracking conditions (dilution 0.33 kg H2O/kg C2H6, continuous addition of 41 ppmw S/HC at T = 1160 K, equivalent ethane conversion 68%). Next to the sequence of the preoxidation and Steam pretreatment, also presulfiding was evaluated. The coking results proved that a high temperature preoxidation, followed by a Steam/air pretreatment at 1173 K for a duration of 15 min, has the best coking performance under ethane Cracking conditions. Thi...
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Thermal Decomposition of Sulfur Compounds and their Role in Coke Formation during Steam Cracking of Heptane
Chemical Engineering & Technology, 2016Co-Authors: Natalia Olahova, Marie Françoise Reyniers, Nenad Ristic, Marko Djokic, Guy B Marin, Ruben Van De Vijver, Kevin Van GeemAbstract:Sulfur-containing compounds play a key role in many industrial processes. Particularly for the Steam Cracking process, they have been linked with increased olefin selectivity, CO formation, and coke inhibition. The influence of four different sulfur-containing additives, methanedithione, (methyldisulfanyl)methane, (methylsulfanyl) methane, and dimethyl sulfoxide, on product selectivity, coke deposition, and CO production during Steam Cracking of a surrogate light naphtha feed is investigated. The use of online comprehensive 2D gas chromatography with sulfur chemiluminescence detection (GCxGC-SCD) is the key enabling technology to characterize the sulfur compounds. Steam Cracking in a pilot-plant unit revealed that all studied sulfur compounds are efficient in reducing the CO yield. Simultaneously, they strongly promote coke.
Guy B Marin - One of the best experts on this subject based on the ideXlab platform.
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pyrometer based control of a Steam Cracking furnace
Chemical Engineering Research & Design, 2020Co-Authors: Stijn Vangaever, Nenad Ristic, Pieter Reyniers, Steffen H Symoens, Marko Djokic, Guy B Marin, Kevin Van GeemAbstract:Abstract Optical thermometry offers great precision, repeatability, flexibility, and stability, hence providing performance advantages in non-contact temperature measurement. To assess its potential for controlling the temperature of Steam Cracking furnaces, ethane Steam Cracking experiments were carried out on pilot plant scale. The control performance of the pyrometer was found to be comparable to that of a weld-on type K thermocouple, the latter being representative of the industrial standard. The tested optical thermometer is suited as a sensor to measure tube metal temperatures of a Steam Cracking reactor coil, either inside or outside of the firebox. Due to its fast response time, optical thermometer temperature measurements help to prevent temperature overshoots, which have an adverse effect on the tube longevity and coke formation. Flexibility in positioning makes optical thermometry a viable alternative compared to conventional type K thermocouples.
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Impact of Initial Surface Roughness and Aging on Coke Formation during Ethane Steam Cracking
Industrial & Engineering Chemistry Research, 2017Co-Authors: Stamatis A. Sarris, Marie Françoise Reyniers, Steffen H Symoens, Guy B Marin, Natalia Olahova, Kim Verbeken, Kevin Van GeemAbstract:Alloys composition and morphology of the inner wall of Steam Cracking reactors are well-known key factors that affect their substantial coking tendency. The effect of surface roughness on the coking tendency remains uncharted so far and has been studied here for a 35/25 Ni/Cr wt % alloy in a quartz jet stirred reactor equipped with an electro-balance, under coil outlet industrially relevant ethane Steam Cracking conditions: Tgas phase = 1173 K, Ptot = 0.1 MPa and XC2H6 = 70 %. Up to 6 times higher initial coking rates have been observed during cyclic aging in an Rα surface roughness range of 0.15 - 7 μm and cyclic aging proved to have an effect mainly on the catalytic coking behavior. No effect was observed on the asymptotic coking rates. Scanning electron microscopy and energy diffractive X-ray surface analysis and cross-section elemental mappings suggest that the effect of surface roughness and aging on the catalytic coking rate derives mainly from changes in the metal surface composition. The amounts o...
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Incident Radiative Heat Flux Based Method for the Coupled Run Length Simulation of Steam Cracking Furnaces
Industrial & Engineering Chemistry Research, 2017Co-Authors: Yu Zhang, Pieter Reyniers, Kevin Van Geem, Feng Qian, Wenli Du, Guy B MarinAbstract:Due to the significant economic penalty associated with decoking Steam Cracking furnaces, accurate run length predictions are crucial for assessing their techno-economic performance. Therefore, for the first time, a full coupled run length simulation of an industrial naphtha Steam Cracking furnace was performed using detailed computational fluid dynamics (CFD) simulations for the furnace side. The results show that the unevenly deposited coke layer within the reactors leads to a redistribution of the thermal power over the time on stream, which is beneficial for the uniformity of the coke growth in the reactor. These effects were not observed in traditional standalone run length simulations, which justifies the high computational cost. However, the high computational cost of these CFD iterations can be overcome by using a novel method which correlates the incident radiative heat flux (IRHF) to the flue gas bridge wall temperature obtained from an overall zero-dimensional heat balance. This so-called IRHF ...
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Computational fluid dynamics‐based Steam Cracking furnace optimization using feedstock flow distribution
Aiche Journal, 2017Co-Authors: Yu Zhang, Pieter Reyniers, Guy B Marin, Kevin Van Geem, Carl Schietekat, Wenli Du, Feng QianAbstract:Nonuniform temperature fields in Steam Cracking furnaces caused by geometry factors such as burner positions, shadow effects, and asymmetry of the reactor coil layout are detrimental for product yields and run lengths. The techniques of adjusting burner firing (zone firing) and feedstock mass flow rate (pass balancing) have been practiced industrially to mitigate these effects but could only reduce the nonuniformities between the so-called modules (a group of many coils).An extension of the pass balancing methodology is presented to further minimize the intra-module nonuniformities, thatis, variation between the coils within a module, in floor fired furnaces. Coupled furnace-reactor computational fluiddynamics-based simulations of an industrial ultraselective conversion (USC) furnace were performed to evaluate fourdifferent feedstock flow distribution schemes, realizing equal values for coil outlet temperature, propene/ethene massratio, maximum coking rate and maximum tube metal temperature (TMT), respectively, over all the reactor coils. It isshown that feedstock flow distribution creates a larger operating window and extends the run length. Out of the fourcases, the coking rate as criterion leads to the highest yearly production capacity for ethene and propene. Uniform maximum coking rates boost the annual production capacity of the USC furnace with a nameplate ethene capacity of 130 103 metric tons per year with 1000 metric tons for ethene and 730 metric tons for propene. For industrial application, achieving uniform maximum TMT is more practical due to its measurability by advanced laser-based techniques. Most Steam Cracking furnaces can be retrofitted by optimizing the dimensions of venturi nozzles that regulate the feedstock flow to the coils. VC 2017 American Institute of Chemical Engineers AIChE J, 63: 3199–3213, 2017Keywords: computational fluid dynamics, Steam Cracking, optimization, flow rate distribution, economics, ethylene
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Thermal Decomposition of Sulfur Compounds and their Role in Coke Formation during Steam Cracking of Heptane
Chemical Engineering & Technology, 2016Co-Authors: Natalia Olahova, Marie Françoise Reyniers, Nenad Ristic, Marko Djokic, Guy B Marin, Ruben Van De Vijver, Kevin Van GeemAbstract:Sulfur-containing compounds play a key role in many industrial processes. Particularly for the Steam Cracking process, they have been linked with increased olefin selectivity, CO formation, and coke inhibition. The influence of four different sulfur-containing additives, methanedithione, (methyldisulfanyl)methane, (methylsulfanyl) methane, and dimethyl sulfoxide, on product selectivity, coke deposition, and CO production during Steam Cracking of a surrogate light naphtha feed is investigated. The use of online comprehensive 2D gas chromatography with sulfur chemiluminescence detection (GCxGC-SCD) is the key enabling technology to characterize the sulfur compounds. Steam Cracking in a pilot-plant unit revealed that all studied sulfur compounds are efficient in reducing the CO yield. Simultaneously, they strongly promote coke.
Masayuki Shirai - One of the best experts on this subject based on the ideXlab platform.
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deactivation of zsm 5 zeolite during catalytic Steam Cracking of n hexane
Fuel Processing Technology, 2014Co-Authors: Aritomo Yamaguchi, Takuji Ikeda, Koichi Sato, Norihito Hiyoshi, Takaaki Hanaoka, Fujio Mizukami, Masayuki ShiraiAbstract:Abstract H-ZSM-5 catalyst was initially active for the Steam Cracking of n-hexane to produce propylene and ethylene; however, the H-ZSM-5 catalyst deactivated. Understanding the deactivation reason of the ZSM-5 catalyst during the catalytic Steam Cracking is essential to develop the durable catalyst. It was revealed that the dealumination of ZSM-5 occurred under the Steam flow at the reaction temperature, from the characterization results of H-ZSM-5 and pre-Steamed H-ZSM-5 by SEM, XRD, ICP, N2 adsorption, 27Al MAS NMR, and NH3-TPD. The coke deposition also occurred during the Steam Cracking of n-hexane as suggested by TG-DTA result of the used H-ZSM-5 catalyst. The used H-ZSM-5 catalysts were regenerated by calcination for a removal of coke deposition and the regenerated catalysts were used for the n-hexane Steam Cracking again. The initial conversion over the regenerated H-ZSM-5 was partially recovered, indicating that the H-ZSM-5 catalyst was deactivated reversibly by the coke deposition and irreversibly by the dealumination during the n-hexane Steam Cracking.
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P-ZSM-5 Pretreated by High-Temperature Calcination as Durable Catalysts for Steam Cracking of n-Hexane
Catalysis Letters, 2014Co-Authors: Aritomo Yamaguchi, Takuji Ikeda, Koichi Sato, Norihito Hiyoshi, Takaaki Hanaoka, Fujio Mizukami, Masayuki ShiraiAbstract:The n -hexane Steam Cracking using the phosphorus-modified ZSM-5 catalysts (P-ZSM-5) with several phosphorus loadings was investigated. The P-ZSM-5 catalyst with 1 wt% phosphorus loading (1P-ZSM-5) showed the most stable activity. The pretreatment of high-temperature calcination enhanced the durability of 1P-ZSM-5. The 1P-ZSM-5 catalyst calcined at 1,073 K remained 80 % of initial activity for 30 h. Graphical Abstract
