scholarly journals Dynamic Simulation of Adiabatic Catalytic Fixed-Bed Tubular Reactors: A Simple Approximate Modeling Approach

2014 ◽  
Vol 14 (1) ◽  
pp. 25
Author(s):  
Wiwut Tanthapanichakoon ◽  
Shinichi Koda ◽  
Burin Khemthong
Keyword(s):  
Dynamic Model ◽  
Dynamic Behavior ◽  
Dynamic Simulation ◽  
Flow Rate ◽  
Fixed Bed ◽  
Axial Dispersion ◽  
Fixed Bed Reactor ◽  
Inlet Temperature ◽  
Acetylene Hydrogenation ◽  
Tubular Reactors

Fixed-bed tubular reactors are used widely in chemical process industries, for example, selective hydrogenation of acetylene to ethylene in a naphtha cracking plant. A dynamic model is required when the effect of large fluctuations with time in influent stream (temperature, pressure, flow rate, and/or composition) on the reactor performance is to be investigated or automatically controlled. To predict approximate dynamic behavior of adiabatic selective acetylene hydrogenation reactors, we proposed a simple 1-dimensional model based on residence time distribution (RTD) effect to represent the cases of plug flow without/with axial dispersion. By modeling the nonideal flow regimes as a number of CSTRs (completely stirred tank reactors) in series to give not only equivalent RTD effect but also theoretically the same dynamic behavior in the case of isothermal first-order reactions, the obtained simple dynamic model consists of a set of nonlinear ODEs (ordinary differential equations), which can simultaneously be integrated using Excel VBA (Visual BASIC Applications) and 4th-order Runge-Kutta algorithm. The effects of reactor inlet temperature, axial dispersion, and flow rate deviation on the dynamic behavior of the system were investigated. In addition, comparison of the simulated effects of flow rate deviation was made between two industrial-size reactors.Keywords: Dynamic simulation, 1-D model, Adiabatic reactor, Acetylene hydrogenation, Fixed-bed reactor, Axial dispersion effect

HAZOP study of a fixed bed reactor for MTBE synthesis using a dynamic approach

2008 ◽  
Vol 62 (1) ◽  
Author(s):  
Juraj Labovský ◽  
Zuzana Švandová ◽  
Jozef Markoš ◽  
L’udovít Jelemenský
Keyword(s):  
Steady State ◽  
Dynamic Simulation ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Inlet Temperature ◽  
Potential Hazard ◽  
Process Unit ◽  
Feed Composition ◽  
Tertiary Butyl ◽  
Wide Range

AbstractA methodology for hazard investigation based on the integration of a mathematical model approach into hazard and operability analysis is presented. This approach is based on mathematical modelling of a process unit where both steady-state analysis, including analysis of the steady states multiplicity and stability, and dynamic simulation are used. The dynamic simulation serves for the investigation of consequences of failures of the main controlled parameters, i.e. inlet temperature, feed temperature and feed composition. This simulation is also very useful for the determination of the influence of failure duration on the reactor behaviour. On the other hand, the steady state simulation can predict the reactor behaviour in a wide range of failure magnitude and determine the parametric zones, where shifting from one steady state to another one may occur. A fixed bed reactor for methyl tertiary-butyl ether synthesis was chosen to identify potential hazard and operational problems of a real process.

Comprehensive Mathematical Modeling and Dynamic Simulation of Fixed Bed Reactor with Finite Element Method

2011 ◽  
Author(s):  
Davood Dehestani ◽  
Hung Nguyen ◽  
Fahimeh Eftekhari ◽  
Jafar Madadnia ◽  
Steven Su ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Simulation ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Element Method

scholarly journals Simulation of CO2 Conversion into Methanol in Fixed-bed Reactors: Comparison of Isothermal and Adiabatic Configurations

REAKTOR ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 131-135
Author(s):  
Fadilla Noor Rahma
Keyword(s):  
Fixed Bed ◽  
Value Added ◽  
Fixed Bed Reactor ◽  
Inlet Temperature ◽  
Methanol Production ◽  
Greenhouse Gases Emissions ◽  
Fixed Bed Reactors ◽  
Adiabatic Reactor ◽  
Co2 Conversion Into Methanol ◽  
Feed Inlet

CO2 capture and utilization (CCU) has been widely considered as a potential solution to overcome global warming. Conversion of CO2 into methanol is an interesting option to transform waste into value-added chemical while also reducing greenhouse gases emissions in the atmosphere. In this paper, utilization of CO2 into methanol was simulated using Aspen Plus software. The reaction between CO2 and H2 to produce methanol and water was carried out in a simulated fixed-bed reactor with Cu/ZnO/Al2O3 commercial catalyst, following LHHW (Langmuir – Hinshelwood – Hougen – Watson) kinetic model. Isothermal and adiabatic reactor configurations were compared under similar feed conditions and the concentration profile along the reactor was observed. The result showed that isothermal configuration converted 3.23% more CO2 and provided 16.34% higher methanol yield compared to the adiabatic reactor. Feed inlet temperature variation was applied and the effect to methanol production on both configurations was studied. The highest methanol yield for adiabatic and isothermal reactor was obtained at 200 oC and 240 oC respectively.

Experimental Study of the Reforming of Methane with Carbon Dioxide over Coal Char

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Yanbing Li ◽  
Rui Xiao ◽  
Baosheng Jin ◽  
Huiyan Zhang
Keyword(s):  
Carbon Dioxide ◽  
Flow Rate ◽  
Fixed Bed ◽  
Coke Oven ◽  
Fixed Bed Reactor ◽  
Internal Diameter ◽  
Generation System ◽  
Coke Oven Gas ◽  
Surface Areas ◽  
Conversion Of Methane

As one of the fundamental issues of the new poly-generation system on the basis of gasification gas and coke oven gas, carbon dioxide reforming of methane experiments have been performed over coal chars derived from different parent coals in a lab-scale fixed-bed reactor (internal diameter 12 mm, length 700 mm). The char derived from TongChuan coal exhibited higher activity than other samples employed under the same conditions. After the reforming reaction, the char samples were covered with different amounts of carbon deposition which resulted in the surface areas decrease. As the flow rate of feed gas increased from 200 ml/min to 600 ml/min over the Xuzhou char sample at 1050 degrees Celsius, the conversion of methane decreased from 52.7% to 17.5% and the H2 /CO dropped from 0.75 to 0.55. While maintaining the flow rate of CO2 at 20ml/min at 1050 degrees Celsius, the mole ratio of reactants CH4/CO2 was varied from 1 to 1.75 which led to the H2/CO ratio increase from 0.75 to 1.2.

Modeling NOx Adsorption onto Fe/ZSM-5 Catalysts in a Fixed Bed Reactor

2013 ◽  
Vol 11 (1) ◽  
pp. 19-30 ◽  
Author(s):  
Xingxing Cheng ◽  
Xiaotao T. Bi
Keyword(s):  
Circulating Fluidized Bed ◽  
Scale Up ◽  
Fixed Bed ◽  
Breakthrough Curves ◽  
Axial Dispersion ◽  
No Oxidation ◽  
Fixed Bed Reactor ◽  
Model Parameters ◽  
Adsorption Model ◽  
Nox Adsorption

Abstract A NOx adsorption kinetic model including NO oxidation and adsorption was developed. The NOx and O2 adsorption experimental data from a fixed bed were found to be fitted well to the Freundlich type isotherm. An axial dispersion adsorption model was then developed to simulate the breakthrough curve for NOx adsorption in the fixed bed. The model parameters including mass transfer coefficient and axial dispersion coefficient were fitted from the NOx breakthrough curves measured in a fixed bed. This model can be used for design and scale-up of fixed bed NOx adsorption columns. It can also be extended for the modeling of NOx adsorption in the annulus region of the circulating fluidized bed reactor for catalytic reduction of NOx.

scholarly journals Simulation and optimization of coupling reaction of methanol synthesis and isopropyl alcohol dehydrogenation

2018 ◽  
Vol 10 (3) ◽  
pp. 127
Author(s):  
Jenny Rizkiana ◽  
Yogi Wibisono Budhi ◽  
Azis Trianto
Keyword(s):  
Methanol Synthesis ◽  
Isopropyl Alcohol ◽  
Fixed Bed ◽  
Coupling Reaction ◽  
Fixed Bed Reactor ◽  
Inlet Temperature ◽  
Simulation And Optimization ◽  
Optimum Operation ◽  
Operation Conditions ◽  
Reaction Conversion

A study on simulation and optimization of coupling reaction between methanol synthesis and isopropyl alcohol (IPA) dehydrogenation was performed. The analysis is carried out theoretically to obtain the optimum operation conditions which give the best performance. The reactions are just interacting thermally. In this study, both reactions are held catalytically in a heat-exchanger type reactor. As a high pressure reaction, methanol synthesis is placed in the inner side of reactor tube while dehydrogenation of IPA is in the opposite. Tube wall acts as a heat transfer media. The reactor is modeled by a steady state heterogeneous equation for a fixed bed reactor. Optimization is done in order to find the optimum value of operation conditions, those are the inlet temperature of both side of reactor and the molar feed flow ratio between the exothermic side and the endothermic side. Sum of weighted reaction conversion is considered to be the objective function that is maximized. The simulation result shows that coupled reactor makes the reaction conversion higher than a conventional adiabatic reactor and the optimum operation conditions give the maximum value of the conversion. This study presents a theoretical proof that coupling reaction is feasible. Keywords: coupling reaction, IPA dehydrogenation, methanol synthesis, optimization, simulated annealingAbstrak Telaah mengenai simulasi dan optimisasi reaksi perangkaian (coupling reaction) antara sintesis metanol dengan dehidrogenasi isopropil alkohol (IPA) telah dilakukan. Analisis dilaksanakan secara teoretik guna mendapatkan kondisi optimum yang akan memberikan hasil terbaik. Pada penelitian ini, kedua reaksi dilaksanakan secara katalitik dalam reaktor bertipe buluh-cangkang. Karena bertekanan tinggi, sintesis metanol ditempatkan pada sisi buluh, sedangkan dehidrogenasi IPA ditempatkan pada sisi cangkang. Dinding buluh berperan sebagai media perpindahan panas. Reaktor dimodelkan dengan reaktor heterogen tunak unggun tetap. Optimisasi dilakukan dalam rangka mendapatkan nilai optimum dari kondisi operasi yang mencakup temperatur inlet sisi eksotermik dan endotermik serta rasio umpan molarnya. Jumlah total konversi reaksi terbobotkan dipilih sebagai nilai objectif yang akan dioptimumkan. Hasil simulasi menunjukkan bahwa reaktor perangkaian termal mampu meningkatkan konversi reaksi jika dibandingkan dengan reaktor adiabatik dan pada kondisi operasi yang optimum diperoleh konversi maksimal. Penelitian ini menunjukkan bahwa reaksi perangkaian layak untuk dilaksanakan.Kata kunci: reaksi perangkaian, dehidrogenasi IPA, sintesis methanol, optimisasi, simulated annealing

The Effects of Methanol on Honehe Lignite Pyrolysis

2013 ◽  
Vol 291-294 ◽  
pp. 748-754
Author(s):  
De Min He ◽  
Jun Guan ◽  
Lin Zhang ◽  
Qiu Min Zhang
Keyword(s):  
Flow Rate ◽  
Functional Group ◽  
Coal Tar ◽  
Fixed Bed ◽  
Holding Time ◽  
Fixed Bed Reactor ◽  
Coal Pyrolysis ◽  
Oxygen Functional Group ◽  
N2 Atmosphere ◽  
N2 Flow Rate

In this paper, the pyrolysis of Honehe Lignite in N2 and N2-Methanol atmospheres were investigated on a fixed-bed reactor. The methanol flow rate, pressure, temperature and holding time were studied. The maximum of coal tar yields 12.01% (with methanol injected in) and 9.61% (absence of methanol) were achieved on the conditions of 520°C, 0.5MPa, N2 flow rate 50ml/min, methanol flow rate 0.1ml/min and holding time 20min, and the relative growing rate was about 25.0%. The gas from coal pyrolysis was detected by GC, and the coal tar was reprocessed and then detected by GC-MS. While the solid char was detected by IR to study the change of oxygen functional group during coal pyrolysis in N2-Methanol atmosphere. Compared with that pyrolysis in N2 atmosphere, the components, characteristics and properties of coal tar, gas and solid char varied a lot. The results showed that the injection of methanol into the system changed the products yields and distribution. The results showed that the total yields of phenol, cresol and xylenol (short for PCX) in the Acidic were about 1.93% and 1.15% (daf) in two atmospheres respectively, the PCX yields with methanol injected was about 1.67 times higher than that absence of methanol.

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