Steady-state multiplicity of a packed-bed reactor operating under a fixed pressure drop

1986 ◽  
Vol 41 (4) ◽  
pp. 749-755 ◽  
Author(s):  
J.P. Lee ◽  
V. Balakotaiah ◽  
D. Luss
Keyword(s):  
Steady State ◽  
Pressure Drop ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Reactor Operating ◽  
State Multiplicity

scholarly journals System Approach from Biomass Combustion in Packed Bed Reactor

2007 ◽  
Vol 7 (1 & 2) ◽  
pp. 16 ◽  
Author(s):  
Anhkien Le ◽  
Le Xuan Hai ◽  
V. N. Sharifi ◽  
J. Swithenbank
Keyword(s):  
Steady State ◽  
Transition Period ◽  
Computing Time ◽  
Substrate Inhibition ◽  
Simple Algorithm ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Biomass Combustion ◽  
Stable Steady State ◽  
State Tests

A simple algorithm originally proposed by Choong, Paterson and Scott (2002) was tested on a model of an isothermal controlled-cycled stirred tank reactor with substrate inhibition kinetics, (r = 1 ~c). In previous work, this reacting system had been shown to exhibit steady-state multiplicity. The transition period of this system to the stable steady state is sometimes characterized by very slow change followed by a very rapid convergence to the stable steady state. Tests of the Choong-Paterson-Scott algorithm showed that the feature, which prevents premature termination of the calculations prior to reaching the true steady state, is very useful for this system. However, tests of the stopping criterion showed that the other feature of reducing the computing time was not realized in this system.

Split Flow Modified Packed Bed Reactor for Cobalt Oxide Based High-Temperature TCES Systems

2019 ◽  
Author(s):  
Nasser Vahedi ◽  
Alparslan Oztekin
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Pressure Drop ◽  
Energy Density ◽  
Redox Reaction ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Flow Ratio ◽  
Packed Bed Reactors ◽  
Split Flow

Abstract The new generation of Concentrated Solar Power (CSP) plants requires high temperature and high energy density storage system with good cyclic stability. The potential solution satisfying such requirements is the thermochemical energy storage (TCES) using gas-solid redox reaction. Design of efficient storage reactor is very critical for applications of such storage systems. Packed bed reactors have a simpler design with no moving components and are more cost-effective compared to other available moving bed design configurations while having high-pressure drop is their main drawback. Any improvement in the pressure drop makes the design more suitable for commercial applications, especially at high temperature operating conditions. Cobalt oxide redox reaction has been considered for this study because of its unique features, especially high enthalpy of reaction (energy density) and high reaction temperature. A rectangular cross-section packed bed reactor with a large aspect ratio is selected as a reference conventional packed bed reactor. The novel split-flow packed bed reactor design configuration is proposed in which a portion of heat transfer fluid is passed through adjacent side channels. The split flow ratio of 1/3 has been considered for the case study. The transient two-dimensional numerical model is developed for solving mass, momentum, and energy equations for both gas and solid phases using suitable reaction kinetics for the reversible reduction and re-oxidation process. Complete storage cycle, including both the charging and discharging mode, has been simulated using finite element method. The split flow design performance is compared with the reference case considering the same size of the reaction bed. It is shown that the conversion time is increased while the pressure drop reduced below half of the pressure loss of the conventional design. Reduced mass flow rate passing through the bed results in considerable improvement in required pressure work with a penalty of storage performance. Further study is needed to optimize the split flow ratio and the surface heat transfer characteristics of the bed. The proposed design configuration could be a breakthrough in packed bed reactors, especially for high-temperature storage applications.

Decomposition of Carbon Tetrachloride by a Packed Bed Plasma Reactor

1997 ◽  
Vol 2 (2) ◽  
Author(s):  
G. Prieto ◽  
O. Prieto ◽  
C. R. Gay ◽  
K. Mizuno ◽  
I. Tamori ◽  
...  
Keyword(s):  
Carbon Tetrachloride ◽  
Plasma Reactor ◽  
Packed Bed ◽  
Operating Conditions ◽  
Empirical Modeling ◽  
Atmospheric Pollutants ◽  
Packed Bed Reactor ◽  
Volatile Organic ◽  
Reactor Operating ◽  
Decomposition Efficiency

AbstractIn search of a technology capable of controlling atmospheric pollutants, like volatile organic compounds (VOCs) in low concentrations, this paper is concerned with the empirical modeling of a ferroelectric plasma packed-bed reactor at ambient temperature and pressure. The empirical model gives information about the decomposition efficiency of the process as a function of the reactor operating variables. The volatile organic compound selected is Carbon Tetrachloride balanced with air in the concentration-range of 150 to 600 ppm and flow-range of 175 to 325 ml/min. Regarding the decomposition efficiency as the objective function, this modeling provides valuable information about the optimal operating conditions.

Steady State Model for Heat Transfer in a Packed Bed Reactor of Elliptic Cylindrical Shape

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Laércio G. Oliveira ◽  
Ramdayal Swarnakar ◽  
Antonio G. B. de Lima
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Fixed Bed ◽  
Packed Bed ◽  
Numerical Results ◽  
Packed Bed Reactor ◽  
Fixed Bed Reactor ◽  
Dimensionless Temperature ◽  
Cylindrical Shape ◽  
Temperature Profiles

The fixed-bed reactors of circular cylindrical geometry with heated or cooled walls are frequently used to carry out heterogeneous reactions of solid-gas type in engineering applications. The design of a fixed bed reactor requires an extensive knowledge of heat transfer characteristics within the packed bed. In this sense, this work presents a three-dimensional mathematical model to predict the heat transfer inside a fixed bed elliptical cylinder heat exchanger. The model considers uniform velocity and temperature profiles of the fluid phase at the entrance of the reactor, and constant thermo-physical properties. The surface of the equipment convective boundary condition is assumed to be constant. The energy equation, written in the elliptical cylindrical coordinates, was discretized using a finite-volume method considering a fully implicit formulation, and WUDS interpolation scheme. Numerical results of the dimensionless temperature profiles inside the packed bed reactor at a steady state are presented and temperature distribution is interpreted. To validate the model, numerical results obtained for the circular cylinder are compared with analytical results from literature and a good agreement was obtained.

scholarly journals Simulation of methanol production from residual biomasses in a Cu/ZnO/Al2O3 packed bed reactor

2020 ◽  
Author(s):  
Carlos Esteban Aristizabal-Alzate ◽  
Andrés Felipe Vargas-Ramírez ◽  
Pedro Nel Alvarado-Torres
Keyword(s):  
Pressure Drop ◽  
Heterogeneous System ◽  
Catalyst Deactivation ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Deactivation Model ◽  
Alcohol Production ◽  
Methanol Production ◽  
Ratio Effect ◽  
Agent Selection

This article aims to simulate an algorithm constructed in MATLAB to represent the catalytic conversion of SYNGAS into methanol in a packed-bed reactor, based on chemical kinetics for a heterogeneous system with a Cu/ZnO/Al2O3 as a catalyst, and complementary math and phenomenological models, as a pressure drop and catalyst deactivation. Model validation is developed, comparing reference results and the results by running the algorithm in MATLAB using a reference SYNGAS composition. Also, the constructed model considers a catalyst deactivation by sintering and pressure drop along the reactor.  Several parameters were evaluated to identify the pro conditions for methyl alcohol production; these parameters include the gasifying agent selection, the biomass and steam ratio effect, and the biomass origin.

scholarly journals Recovery of UAPB from high organic load during startup for phenolic wastewater treatment

2011 ◽  
Vol 17 (4) ◽  
pp. 517-524 ◽  
Author(s):  
Zeinab Bakhshi ◽  
Ghasem Najafpour ◽  
Neya Navayi ◽  
Esmaeel Kariminezhad ◽  
Roya Pishgar ◽  
...  
Keyword(s):  
Steady State ◽  
Removal Efficiency ◽  
Biogas Production ◽  
Phase 1 ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Phenol Concentration ◽  
Synthetic Wastewater ◽  
Organic Load ◽  
Phenol Removal

Biodegradation of synthetic wastewater containing phenol by upflow anaerobic packed bed reactor (UAPB) was studied in this work. The reactor was operated at a hydraulic retention time (HRT) of 24 h and under mesophilic (30?1?C) conditions. The startup operation was conducted for 150 days; split into 4 phases. The phenol concentration was stepwise increased. The concentration of phenol in phases 1, 2, 3 and 4 were 100, 400, 700 and 1000 mg/l, respectively. In phase 1, the reactor reached steady state conditions on the 8th day with a phenol removal efficiency and biogas production rate of 96.8% and 1.42 l/d, respectively. For an increase of the initial phenol concentration in phase 2, a slight decrease in phenol removal efficiency was observed. Similar trends were observed in phases 3 and 4 of startup. Due to the high phenol concentration a sudden decrease in removal efficiency and biogas production was observed. The surviving microorganisms were gradually adapted and acclimated to high phenol concentrations. In phases 3 and 4, the phenol removal efficiency at steady state conditions were 98.4 and 98%, respectively. The maximum biogas production was observed at day 130 with a value of 3.57 l/d that corresponds to phenol concentration of 1000 mg/l.

Parametric Study of Split Flow Cylindrical Packed Bed Reactor for High-Temperature Thermochemical Energy Storage Using Cobalt Oxide Redox Reaction

2019 ◽  
Author(s):  
Nasser Vahedi ◽  
Alparslan Oztekin
Keyword(s):  
High Temperature ◽  
Energy Storage ◽  
Pressure Drop ◽  
Parametric Study ◽  
Redox Reaction ◽  
Packed Bed ◽  
Reactor Design ◽  
Packed Bed Reactor ◽  
Reactor Performance ◽  
Split Flow

Abstract Thermal energy storage has become an integral part of Concentrated Solar Power (CSP) plants to guarantee continuous supply of power demand. For cost-effective solar power generation, the size and operating temperatures of CSP plants should be increased. Thermochemical energy storage (TCES) is the only available solution to meet energy density and high-temperature requirements. Air is mostly used as Heat Transfer Fluid (HTF) for high-temperature CSP plants. For the air-based system, metal redox reactions are good candidates as storage reactant. Application of metal oxide gas-solid redox reaction in storage systems requires an efficient reactor design. Cost-effectiveness and simplicity have made packed bed reactors a viable candidate for high-temperature applications. The high-pressure drop along the bed is the main drawback of such reactors preventing them from widespread applications. Split flow design modification could aid in reducing pressure drop while providing more flexibility in reactor performance control. A cylindrical split-flow packed bed reactor with an annulus for HTF flow is considered as a modified reactor design. The transient two-dimensional axisymmetric numerical model is developed for solving mass, momentum, and energy equations for both gas and solid phases using suitable reaction kinetics for the cobalt oxide redox reaction. A parametric study is performed on cylindrical-shaped split-flow reactor design as a basis for future optimization for complete storage cycle. The effect of split flow ratio and side-channel width on reactor performance are considered. It is shown that both parameters could be used effectively to design and optimize the reactor.

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