The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform

Costin Sorin Bildea - One of the best experts on this subject based on the ideXlab platform.

  • Integrated design and control of plantwide systems coupling exothermic and Endothermic Reactions
    Computers & Chemical Engineering, 2009
    Co-Authors: Pietro Altimari, Costin Sorin Bildea
    Abstract:

    Abstract The problem of integrated design and control of plantwide systems coupling Endothermic and exothermic Reactions is addressed. Processes simultaneously carrying on the Endothermic first-order reaction A  →  R  +  Q and the exothermic second-order reaction B  +  Q  →  P are considered. As the physical properties of the species involved vary, possible flowsheets are identified and feasible control strategies are suggested. Multiple steady states are detected at fixed values of the plantwide-control variables. Singularity theory is exploited to divide the space of reactor-design parameters into regions characterized by qualitatively different solution diagrams. The implications of the observed behaviour on plant controllability are thoroughly discussed.

  • Steady-state behaviour of PFR-separation-recycle systems with simultaneous exothermic and Endothermic, first-order Reactions
    Computers & Chemical Engineering, 2009
    Co-Authors: Klaas Steur, Costin Sorin Bildea, Pietro Altimari, Alexandre C. Dimian
    Abstract:

    A systematic investigation of plug-flow reactor (PFR)-separation-recycle systems where first-order exothermic and Endothermic Reactions are simultaneously performed is presented. The nonlinear behaviour is analyzed for two flowsheet alternatives and four plantwide control structures. It is shown that the system can exhibit a complex nonlinear behaviour. For the parameter values used, regions of unfeasibility, two or three multiple steady states and branches of isolated solutions were found. The undesired nonlinear phenomena can be avoided by fixing the reactor-inlet flow rates of each reactant or, when this is impossible due to the flowsheet structure, by providing sufficient cooling capacity.

  • coupling exothermic and Endothermic Reactions in plug flow reactor separation recycle systems
    Industrial & Engineering Chemistry Research, 2008
    Co-Authors: Pietro Altimari, Costin Sorin Bildea
    Abstract:

    The nonlinear behavior of plug-flow reactor−separation−recycle systems, where the Endothermic first-order reaction A → R + Q and the exothermic second-order reaction B + Q → P simultaneously take place, is investigated. As the physical properties of the species involved vary, possible flowsheets are identified and feasible control strategies are suggested. Bifurcation analysis of the reactor−separation−recycle system is performed by choosing set-point variables as bifurcation parameters. Steady state multiplicity is invariably detected leading to complex behavior. Implications on plantwide control are thoroughly discussed and guidelines are provided which enable to select values of set-point variables in a way that guarantees safe operation.

  • Design and control of PFR - Separation - Recycle systems with simultaneous exothermic and Endothermic Reactions
    Computer Aided Chemical Engineering, 2007
    Co-Authors: Costin Sorin Bildea, Klaas Steur, Alexandre C. Dimian
    Abstract:

    Abstract The paper presents a systematic investigation of PFR - Separator - Recycle systems where exothermic and Endothermic Reactions are simultaneously performed. The nonlinear behaviour is analyzed, for two flowsheet alternatives and four plantwide control structures. It is shown that complex and undesired nonlinear phenomena can be avoided by providing sufficient cooling capacity or by controlling the flow rate of each reactant at reactor inlet.

Pietro Altimari - One of the best experts on this subject based on the ideXlab platform.

  • Integrated design and control of plantwide systems coupling exothermic and Endothermic Reactions
    Computers & Chemical Engineering, 2009
    Co-Authors: Pietro Altimari, Costin Sorin Bildea
    Abstract:

    Abstract The problem of integrated design and control of plantwide systems coupling Endothermic and exothermic Reactions is addressed. Processes simultaneously carrying on the Endothermic first-order reaction A  →  R  +  Q and the exothermic second-order reaction B  +  Q  →  P are considered. As the physical properties of the species involved vary, possible flowsheets are identified and feasible control strategies are suggested. Multiple steady states are detected at fixed values of the plantwide-control variables. Singularity theory is exploited to divide the space of reactor-design parameters into regions characterized by qualitatively different solution diagrams. The implications of the observed behaviour on plant controllability are thoroughly discussed.

  • Steady-state behaviour of PFR-separation-recycle systems with simultaneous exothermic and Endothermic, first-order Reactions
    Computers & Chemical Engineering, 2009
    Co-Authors: Klaas Steur, Costin Sorin Bildea, Pietro Altimari, Alexandre C. Dimian
    Abstract:

    A systematic investigation of plug-flow reactor (PFR)-separation-recycle systems where first-order exothermic and Endothermic Reactions are simultaneously performed is presented. The nonlinear behaviour is analyzed for two flowsheet alternatives and four plantwide control structures. It is shown that the system can exhibit a complex nonlinear behaviour. For the parameter values used, regions of unfeasibility, two or three multiple steady states and branches of isolated solutions were found. The undesired nonlinear phenomena can be avoided by fixing the reactor-inlet flow rates of each reactant or, when this is impossible due to the flowsheet structure, by providing sufficient cooling capacity.

  • coupling exothermic and Endothermic Reactions in plug flow reactor separation recycle systems
    Industrial & Engineering Chemistry Research, 2008
    Co-Authors: Pietro Altimari, Costin Sorin Bildea
    Abstract:

    The nonlinear behavior of plug-flow reactor−separation−recycle systems, where the Endothermic first-order reaction A → R + Q and the exothermic second-order reaction B + Q → P simultaneously take place, is investigated. As the physical properties of the species involved vary, possible flowsheets are identified and feasible control strategies are suggested. Bifurcation analysis of the reactor−separation−recycle system is performed by choosing set-point variables as bifurcation parameters. Steady state multiplicity is invariably detected leading to complex behavior. Implications on plantwide control are thoroughly discussed and guidelines are provided which enable to select values of set-point variables in a way that guarantees safe operation.

Byung-hun Jeong - One of the best experts on this subject based on the ideXlab platform.

  • Decomposition of Endothermic fuel using washcoated HZSM-5 on metal foam
    Catalysis Today, 2020
    Co-Authors: Jeongin Mun, Byung-hun Jeong, Hoyeol Jeon, Jihoon Jung
    Abstract:

    Abstract Cooling technology exploiting the Endothermic reaction of fuel has been developed to prevent structural deformation in engines due to air friction and overheating during supersonic flight. Endothermic fuels are liquid hydrocarbon fuels that can absorb heat through Endothermic Reactions. The initial heat sink capacity of conventional pellet type catalysts for the Endothermic reaction cannot be maintained, leading to more rapid deactivation due to coke formation. To maintain the heat sink performance of decomposition catalysts, HZSM-5 catalyst washcoated on metal foam(HZSM-5/metal foam) was used herein. The Reactions were carried out in a batch reactor at 673 K at a pressure of 50 bar using methylcyclohexane (MCH) and n-dodecane as reactants. The total MCH conversion achieved with the pellets and HZSM-5/metal foam was same at 93 %. In the case of n-dodecane, the total conversion achieved with the HZSM-5/metal foam (91 %) was superior to that achieved with the pellets (69 %).

  • catalytic Endothermic Reactions of exo tetrahydrodicyclopentadiene with zeolites and improvement of heat of Reactions
    Catalysis Today, 2014
    Co-Authors: Dong Hun Hyeon, Byung Hee Chun, Sun-hee Park, Byung-hun Jeong
    Abstract:

    Abstract Catalytic Endothermic Reactions of exo -tetrahydrodicyclopentadiene ( exo -THDCP) with different zeolites were investigated in a batch reactor to increase the heat of reaction. The heat of reaction with each zeolite was calculated by the NIST SUPERTRAPP program. The conversion and product distribution were also investigated because they affected the heat of reaction. The heat of reaction of HZSM-5 was larger than those of other zeolite due to its total acid density and pore structures. It showed the highest conversion and highest composition of low molecular weight products. Because dehydrogenation can increase Endothermic heat, Pt/HZSM-5 (1 wt% Pt loaded) was used in the Endothermic reaction. The metal sites led the dehydrogenation of saturated hydrocarbons and increase in olefins. To increase the heat of reaction, high conversion and high yield of low molecular weight hydrocarbons and olefins are necessary.

  • improvement of the heats of reaction in Endothermic Reactions of methylcyclohexane with zeolites
    Catalysis Today, 2012
    Co-Authors: Sun-hee Park, Byung Hee Chun, Byung-hun Jeong
    Abstract:

    Abstract Endothermic Reactions of methylcyclohexane (MCH) with zeolites were investigated in a batch reactor to increase the heats of reaction. Conversion and product distribution affected the heat of reaction. The heat of reaction with HZSM-5, which led to the formation of low-molecular-weight hydrocarbon products, was larger than the heats of reaction with other zeolites. To improve the heat of reaction with HZSM-5, Pt/HZSM-5 (1 wt.% Pt) was used in Endothermic Reactions. In Endothermic Reactions with Pt/HZSM-5, the heats of reaction increased, and there was a high yield of olefins, which were formed by dehydrogenation of paraffin on metal sites. A high conversion and high yield of low-molecular-weight hydrocarbons and olefins led to an increase in the heat of reaction.

Hongfei Cheng - One of the best experts on this subject based on the ideXlab platform.

  • thermal behavior and decomposition of kaolinite potassium acetate intercalation composite
    Thermochimica Acta, 2010
    Co-Authors: Hongfei Cheng, Jing Yang, Qinfu Liu, Qian Zhang
    Abstract:

    A series of kaolinite-potassium acetate intercalation composite was prepared. The thermal behavior and decomposition of these composites were investigated by simultaneous differential scanning calorimetry-thermogravimetric analysis (DSC-TGA), X-ray diffraction (XRD) and Fourier-transformation infrared (FT-IR). The XRD pattern at room temperature indicated that intercalation of potassium acetate into kaolinite causes an increase of the basal spacing from 0.718 to 1.428nm. The peak intensity of the expanded phase of the composite decreased with heating above 300°C, and the basal spacing reduced to 1.19nm at 350°C and 0.718nm at 400°C. These were supported by DSC-TGA and FT-IR measurements, where the Endothermic Reactions are observed between 300 and 600°C. These Reactions can be divided into two stages: 1) Removal of the intercalated molecules between 300-400°C. 2) Dehydroxylation of kaolinite between 400-600°C. Significant changes were observed in the infrared bands assigned to outer surface hydroxyl, inner surface hydroxyl, inner hydroxyl and hydrogen bands.

  • Thermal behavior and decomposition of kaolinite–potassium acetate intercalation composite
    Thermochimica Acta, 2010
    Co-Authors: Hongfei Cheng, Jing Yang, Qinfu Liu, Qian Zhang
    Abstract:

    A series of kaolinite-potassium acetate intercalation composite was prepared. The thermal behavior and decomposition of these composites were investigated by simultaneous differential scanning calorimetry-thermogravimetric analysis (DSC-TGA), X-ray diffraction (XRD) and Fourier-transformation infrared (FT-IR). The XRD pattern at room temperature indicated that intercalation of potassium acetate into kaolinite causes an increase of the basal spacing from 0.718 to 1.428nm. The peak intensity of the expanded phase of the composite decreased with heating above 300°C, and the basal spacing reduced to 1.19nm at 350°C and 0.718nm at 400°C. These were supported by DSC-TGA and FT-IR measurements, where the Endothermic Reactions are observed between 300 and 600°C. These Reactions can be divided into two stages: 1) Removal of the intercalated molecules between 300-400°C. 2) Dehydroxylation of kaolinite between 400-600°C. Significant changes were observed in the infrared bands assigned to outer surface hydroxyl, inner surface hydroxyl, inner hydroxyl and hydrogen bands.

Milorad P. Dudukovic - One of the best experts on this subject based on the ideXlab platform.

  • coupling exothermic and Endothermic Reactions in adiabatic reactors
    Chemical Engineering Science, 2008
    Co-Authors: R C Ramaswamy, P. A. Ramachandran, Milorad P. Dudukovic
    Abstract:

    Abstract The steady state and the dynamic behavior of coupling exothermic and Endothermic Reactions in directly coupled adiabatic packed bed reactors (DCAR) are analyzed using one-dimensional pseudo-homogeneous plug flow model. Two different configurations of DCAR (simultaneous DCAR—SIMDCAR and sequential DCAR—SEQDCAR) are investigated. In SIMDCAR, the catalyst bed favors both exothermic and Endothermic Reactions and both Reactions occur simultaneously. SEQDCAR has alternating layers of catalyst beds for exothermic and Endothermic Reactions and hence the exothermic and Endothermic Reactions occur in a sequential fashion. The performance of both reactors, in terms of conversion achieved and manifested hot spot behavior, is compared with that of the co-current heat exchanger type reactor. Various possible operational regimes in SIMDCAR have been classified and the conditions for the existence of hot spots or cold spots in SIMDCAR are obtained analytically for the first order Reactions with equal activation energies. The reactor behavior for the Reactions with non-equal activation energies is also presented. The preliminary criteria for the selection of suitable reactor type and the general bounds on the reaction parameters to obtain the desired conversion for Endothermic reaction with minimal temperature rise are proposed. The dynamic behavior of these reactors is important for control applications and we have reported some of the transient behavior.

  • recuperative coupling of exothermic and Endothermic Reactions
    Chemical Engineering Science, 2006
    Co-Authors: R C Ramaswamy, P. A. Ramachandran, Milorad P. Dudukovic
    Abstract:

    Coupling energy intensive Endothermic reaction systems with suitable exothermic Reactions improves the thermal efficiency of processes and reduces the size of the reactors. One type of reactor suitable for such a type of coupling is the heat exchanger reactor. In this work, a one-dimensional pseudo-homogeneous plug flow model is used to analyze and compare the performance of co-current and counter-current heat exchanger reactors. A parametric analysis is carried out to address the vital issues, such as the exit conversion of the Endothermic reaction, the temperature peak (hot spot) of the exothermic reaction and the reactor volumetric productivity. The measures to reduce the hot spot by different catalyst profiling techniques are also addressed. Some features of the dynamic behavior exhibited by these reactors, which are important from design, operational and control point of view, are presented.

  • A bidirectional fixed-bed reactor for coupling of exothermic and Endothermic Reactions
    AIChE Journal, 1996
    Co-Authors: Milind S. Kulkarni, Milorad P. Dudukovic
    Abstract:

    Performance of a bidirectional fixed-bed reactor subject to both flow reversal and switching between exothermic and Endothermic Reactions is simulated. During odd semicycles (blows) an exothermic reaction heats the bed, during even semicycles an Endothermic reaction cools the bed and produces the desired product in the hot zone. Such an operation is possible and efficient when the inlet gas temperature is lower than the initial bed temperature, leading to the wrong-way behavior when the temperature front moves with a finite velocity (creep velocity) from the feed end to the exit during a semicycle. Since the dynamic nature of the fixed-bed reactor changes with each semicycle, the front velocity during an exothermic semicycle differs from the front velocity during an Endothermic semicycle and an asymptotic expression is developed for the differential creep (front) velocity that quantifies this difference. Due to a nonzero differential creep velocity, the front exhibits an effective displacement after each cycle. This asymptotic expression for the creep velocity works very well except in the inlet and outlet region of the fixed-bed reactor. An expression developed for 100% energy efficiency shows that it can be reached only if the differential creep velocity is zero. A relation for the balanced operation of a reactor-regenerator is discussed as well as differences in reactor performance caused by Reactions occurring in the gas or solid phase.