Dynamic Modeling of CATOFIN® Fixed-Bed Iso-Butane Dehydrogenation Reactor for Operational Optimization

2016 ◽  
Vol 14 (1) ◽  
pp. 491-515 ◽  
Author(s):  
Zeeshan Nawaz
Keyword(s):  
Coke Formation ◽  
Fixed Bed ◽  
Process Intensification ◽  
Operating Conditions ◽  
Catalytic Dehydrogenation ◽  
Heating Rates ◽  
Reactor Model ◽  
Fuel Gas ◽  
Bed Temperature ◽  
Operational Optimization

AbstractThe catalytic dehydrogenation of iso-butane to iso-butylene is an equilibrium limited endothermic reaction and requires high temperature. The catalyst deactivates quickly, due to deposition of carbonaceous species and countered by periodic regeneration. The reaction-engineering constraints are tied up with operation and/or technology design features. CATOFIN® is a sophisticated commercialized technology for propane/iso-butane dehydrogenation using multiple adiabatic fixed-bed reactors having Cr2O3/Al2O3 as catalyst, that undergo cyclic operations (~18–30m); dehydrogenation, regeneration, evacuation, purging and reduction. It is always a concern, how to maintain CATOFIN® reactor at an optimum production, while overcoming gradual decrease of heat in catalyst bed and deactivation. A homogeneous one-dimensional dynamic reactor model for a commercial CATOFIN® fixed-bed iso-butane dehydrogenation reactor is developed in an equation oriented (EO) platform Aspen Custom Modeler (ACM), for operational optimization and process intensification. Both reaction and regeneration steps were modeled and results were validated. The model predicts the dynamic behavior and demonstrates the extent of catalyst utilization with operating conditions and time, coke formation and removal, etc. The model computes optimum catalyst bed temperature profiles, feed rate, pre-heating, rates for reaction and regeneration, fuel gas requirement, optimum catalyst amount, overall cycle time optimization, and suggest best operational philosophy.

scholarly journals Inductive Heating Assisted-Catalytic Dehydrogenation of Tetralin as a Hydrogen Source for Downhole Catalytic Upgrading of Heavy Oil

2019 ◽  
Vol 63 (3-4) ◽  
pp. 268-280 ◽  
Author(s):  
Abarasi Hart ◽  
Mohamed Adam ◽  
John P. Robinson ◽  
Sean P. Rigby ◽  
Joseph Wood
Keyword(s):  
Catalyst Deactivation ◽  
Oil Quality ◽  
Coke Formation ◽  
Coke Deposition ◽  
Conventional Heating ◽  
Inductive Heating ◽  
Catalytic Dehydrogenation ◽  
Catalytic Upgrading ◽  
Bed Temperature

AbstractThe Toe-to-Heel Air Injection (THAI) combined with a catalytic add-on (CAPRI, CATalytic upgrading PRocess In-situ) have been a subject of investigation since 2002. The major challenges have been catalyst deactivation due to coke deposition and low temperatures (~ 300 °C) of the mobilised hot oil flowing over the catalyst packing around the horizontal well. Tetralin has been used to suppress coke formation and also improve upgraded oil quality due to its hydrogen-donor capability. Herein, inductive heating (IH) incorporated to the horizontal production well is investigated as one means to resolve the temperature shortfall. The effect of reaction temperature on tetralin dehydrogenation and hydrogen evolution over NiMo/Al2O3 catalyst at 250–350 °C, catalyst-to-steel ball ratio (70% v/v), 18 bar and 0.75 h−1 was investigated. As temperature increased from 250 to 350 °C, tetralin conversion increased from 40 to 88% while liberated hydrogen increased from 0.36 to 0.88 mol based on 0.61 mol of tetralin used. The evolved hydrogen in situ hydrogenated unreacted tetralin to trans and cis-decalins with the selectivity of cis-decalin slightly more at 250 °C while at 300–350 °C trans-decalin showed superior selectivity. With IH the catalyst bed temperature was closer to the desired temperature (300 °C) with a mean of 299.2 °C while conventional heating is 294.3 °C. This thermal advantage and the nonthermal effect from electromagnetic field under IH improved catalytic activity and reaction rate, though coke formation increased.

Investigation of Ammonia Formation During Gasification in an Air Blown Spouted Bed

2002 ◽  
Author(s):  
N. Paterson ◽  
Y. Zhuo ◽  
D. R. Dugwell ◽  
R. Kandiyoti
Keyword(s):  
Temperature Control ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Laboratory Scale ◽  
Spouted Bed ◽  
Fuel Gas ◽  
Bed Temperature ◽  
Control Options ◽  
High Concentrations ◽  
Ammonia Formation

High NH3 concentrations were measured in the fuel gas produced by a pilot scale, air blown gasifier that was operated by British Coal. A laboratory scale gasifier has subsequently been developed to investigate the reactions that produce these potentially high concentrations. It has been found that in addition to the NH3 formed through pyrolytic processes, the introduction of steam (or H2 produced by its decomposition) increases the amount formed. The latter reaction produced the higher proportion of the total NH3. The effect of the gasifier operating conditions on the amount of NH3 formed has been studied. The main control options to minimise the NH3 formed are using an alternative method of bed temperature control (i.e. avoid the use of steam), operating with higher bed temperatures and operation at lower pressures.

Tertiary Nitrification Pilot Plants on Parisian Waste Water

1990 ◽  
Vol 22 (1-2) ◽  
pp. 347-352 ◽  
Author(s):  
C. Paffoni ◽  
B. Védry ◽  
M. Gousailles
Keyword(s):  
Waste Water ◽  
Metropolitan Area ◽  
Fixed Bed ◽  
Point Of View ◽  
Operating Conditions ◽  
Research Center ◽  
Daily Output ◽  
Practical Point ◽  
Fixed Bed Reactors

The Paris Metropolitan area, which contains over eight million inhabitants, has a daily output of about 3 M cu.meters of wastewater, the purification of which is achieved by SIAAP (Paris Metropolitan Area Sewage Service) in both Achères and Valenton plants. The carbon pollution is eliminated from over 2 M cu.m/day at Achères. In order to improve the quality of output water, its tertiary nitrification in fixed-bed reactors has been contemplated. The BIOFOR (Degremont) and BIOCARBONE (OTV) processes could be tested in semi-industrial pilot reactors at the CRITER research center of SIAAP. At a reference temperature of 13°C, the removed load is approximately 0.5 kg N NH4/m3.day. From a practical point of view, it may be asserted that in such operating conditions as should be at the Achères plant, one cubic meter of filter can handle the tertiary nitification of one cubic meter of purified water per hour at an effluent temperature of 13°C.

scholarly journals Modeling of a Real-Life Industrial Reactor for Hydrogenation of Benzene Process

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 412
Author(s):  
Mirosław K. Szukiewicz ◽  
Krzysztof Kaczmarski
Keyword(s):  
Catalyst Activity ◽  
Real Life ◽  
Operating Conditions ◽  
Reactor Operation ◽  
Reactor Model ◽  
High Scale ◽  
Industrial Reactor ◽  
Knowledge Based ◽  
Operation Conditions ◽  
Insight Into

A dynamic model of the hydrogenation of benzene to cyclohexane reaction in a real-life industrial reactor is elaborated. Transformations of the model leading to satisfactory results are presented and discussed. Operating conditions accepted in the simulations are identical to those observed in the chemical plant. Under those conditions, some components of the reaction mixture vanish, and the diffusion coefficients of the components vary along the reactor (they are strongly concentration-dependent). We came up with a final reactor model predicting with reasonable accuracy the reaction mixture’s outlet composition and temperature profile throughout the process. Additionally, the model enables the anticipation of catalyst activity and the remaining deactivated catalyst lifetime. Conclusions concerning reactor operation conditions resulting from the simulations are presented as well. Since the model provides deep insight into the process of simulating, it allows us to make knowledge-based decisions. It should be pointed out that improvements in the process run, related to operating conditions, or catalyst application, or both on account of the high scale of the process and its expected growth, will remarkably influence both the profits and environmental protection.

scholarly journals Simulation of a Downdraft Gasifier for Production of Syngas from Different Biomass Feedstocks

2021 ◽  
Vol 5 (2) ◽  
pp. 20
Author(s):  
Mateus Paiva ◽  
Admilson Vieira ◽  
Helder T. Gomes ◽  
Paulo Brito
Keyword(s):  
Modeling And Simulation ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Fuel Gas ◽  
Heating Value ◽  
Downdraft Gasifier ◽  
Process Operation ◽  
Independent Parameters ◽  
Gasification Temperature ◽  
Main Operating

In the evaluation of gasification processes, estimating the composition of the fuel gas for different conditions is fundamental to identify the best operating conditions. In this way, modeling and simulation of gasification provide an analysis of the process performance, allowing for resource and time savings in pilot-scale process operation, as it predicts the behavior and analyzes the effects of different variables on the process. Thus, the focus of this work was the modeling and simulation of biomass gasification processes using the UniSim Design chemical process software, in order to satisfactorily reproduce the operation behavior of a downdraft gasifier. The study was performed for two residual biomasses (forest and agricultural) in order to predict the produced syngas composition. The reactors simulated gasification by minimizing the free energy of Gibbs. The main operating parameters considered were the equivalence ratio (ER), steam to biomass ratio (SBR), and gasification temperature (independent variables). In the simulations, a sensitivity analysis was carried out, where the effects of these parameters on the composition of syngas, flow of syngas, and heating value (dependent variables) were studied, in order to maximize these three variables in the process with the choice of the best parameters of operation. The model is able to predict the performance of the gasifier and it is qualified to analyze the behavior of the independent parameters in the gasification results. With a temperature between 850 and 950 °C, SBR up to 0.2, and ER between 0.3 and 0.5, the best operating conditions are obtained for maximizing the composition of the syngas in CO and H2.

scholarly journals Catalytic Hot Gas Cleanup of Biomass Gasification Producer Gas via Steam Reforming Using Nickel-Supported Clay Minerals

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1875
Author(s):  
Prashanth Reddy Buchireddy ◽  
Devin Peck ◽  
Mark Zappi ◽  
Ray Mark Bricka
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Steam Reforming ◽  
Catalyst Deactivation ◽  
Nickel Content ◽  
Coke Formation ◽  
Biomass Gasification ◽  
Supported Nickel Catalyst ◽  
Fuel Gas ◽  
Removal Efficiencies

Amongst the issues associated with the commercialization of biomass gasification, the presence of tars has been one of the most difficult aspects to address. Tars are an impurity generated from the gasifier and upon their condensation cause problems in downstream equipment including plugging, blockages, corrosion, and major catalyst deactivation. These problems lead to losses of efficiency as well as potential maintenance issues resulting from damaged processing units. Therefore, the removal of tars is necessary in order for the effective operation of a biomass gasification facility for the production of high-value fuel gas. The catalytic activity of montmorillonite and montmorillonite-supported nickel as tar removal catalysts will be investigated in this study. Ni-montmorillonite catalyst was prepared, characterized, and tested in a laboratory-scale reactor for its efficiency in reforming tars using naphthalene as a tar model compound. Efficacy of montmorillonite-supported nickel catalyst was tested as a function of nickel content, reaction temperature, steam-to-carbon ratio, and naphthalene loading. The results demonstrate that montmorillonite is catalytically active in removing naphthalene. Ni-montmorillonite had high activity towards naphthalene removal via steam reforming, with removal efficiencies greater than 99%. The activation energy was calculated for Ni-montmorillonite assuming first-order kinetics and was found to be 84.5 kJ/mole in accordance with the literature. Long-term activity tests were also conducted and showed that the catalyst was active with naphthalene removal efficiencies greater than 95% maintained over a 97-h test period. A little loss of activity was observed with a removal decrease from 97% to 95%. To investigate the decrease in catalytic activity, characterization of fresh and used catalyst samples was performed using thermogravimetric analysis, transmission electron microscopy, X-ray diffraction, and surface area analysis. The loss in activity was attributed to a decrease in catalyst surface area caused by nickel sintering and coke formation.

scholarly journals Experimental Investigation of Oxygen Carrier Aided Combustion (OCAC) with Methane and PSA Off-Gas

2020 ◽  
Vol 11 (1) ◽  
pp. 210
Author(s):  
Viktor Stenberg ◽  
Magnus Rydén ◽  
Tobias Mattisson ◽  
Anders Lyngfelt
Keyword(s):  
Oxygen Carrier ◽  
Silica Sand ◽  
Fuel Conversion ◽  
Fuel Gas ◽  
Bed Temperature ◽  
Bed Materials ◽  
Distribution Plate ◽  
Bed Material ◽  
Gas Conversion ◽  
No Emissions

Oxygen carrier aided combustion (OCAC) is utilized to promote the combustion of relatively stable fuels already in the dense bed of bubbling fluidized beds by adding a new mechanism of fuel conversion, i.e., direct gas–solid reaction between the metal oxide and the fuel. Methane and a fuel gas mixture (PSA off-gas) consisting of H2, CH4 and CO were used as fuel. Two oxygen carrier bed materials—ilmenite and synthetic particles of calcium manganate—were investigated and compared to silica sand, an in this context inert bed material. The results with methane show that the fuel conversion is significantly higher inside the bed when using oxygen carrier particles, where the calcium manganate material displayed the highest conversion. In total, 99.3–99.7% of the methane was converted at 900 °C with ilmenite and calcium manganate as a bed material at the measurement point 9 cm above the distribution plate, whereas the bed with sand resulted in a gas conversion of 86.7%. Operation with PSA off-gas as fuel showed an overall high gas conversion at moderate temperatures (600–750 °C) and only minor differences were observed for the different bed materials. NO emissions were generally low, apart from the cases where a significant part of the fuel conversion took place above the bed, essentially causing flame combustion. The NO concentration was low in the bed with both fuels and especially low with PSA off-gas as fuel. No more than 11 ppm was detected at any height in the reactor, with any of the bed materials, in the bed temperature range of 700–750 °C.

Hydrogen Production via Catalytic Autothermal Reforming of Desulfurized Jet-A Fuel

2016 ◽  
Author(s):  
Shuyang Zhang ◽  
Xiaoxin Wang ◽  
Peiwen Li
Keyword(s):  
Energy Efficiency ◽  
Hydrogen Production ◽  
Hydrogen Storage ◽  
Coke Formation ◽  
Autothermal Reforming ◽  
Operating Conditions ◽  
Hydrogen Yield ◽  
Fuel Conversion ◽  
Optimal Operating ◽  
Reaction Equilibrium

On-board hydrogen production via catalytic autothermal reforming is beneficial to vehicles using fuel cells because it eliminates the challenges of hydrogen storage. As the primary fuel for both civilian and military air flight application, Jet-A fuel (after desulfurization) was reformed for making hydrogen-rich fuels in this study using an in-house-made Rh/NiO/K-La-Ce-Al-OX ATR catalyst under various operating conditions. Based on the preliminary thermodynamic analysis of reaction equilibrium, important parameters such as ratios of H2O/C and O2/C were selected, in the range of 1.1–2.5 and 0.5–1.0, respectively. The optimal operating conditions were experimentally obtained at the reactor’s temperature of 696.2 °C, which gave H2O/C = 2.5 and O2/C = 0.5, and the obtained fuel conversion percentage, hydrogen yield (can be large than 1 from definition), and energy efficiency were 88.66%, 143.84%, and 64.74%, respectively. In addition, a discussion of the concentration variation of CO and CO2 at different H2O/C, as well as the analysis of fuel conversion profile, leads to the finding of effective approaches for suppression of coke formation.

Modeling of a Fixed-Bed Reactor for the Production of Phthalic Anhydride

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Amir Rahimi ◽  
Sogand Hamidi
Keyword(s):  
Phthalic Anhydride ◽  
Fixed Bed ◽  
Tubular Reactor ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Conversion Degree ◽  
Reactor Length ◽  
Reactor Temperature ◽  
Reported Data ◽  
Reactor Pressure

In this study, the performance of a fixed–bed tubular reactor for the production of phthalic anhydride is mathematically analyzed. The conversion degree and reactor temperature values are compared with the measured one in a tubular reactor applied in Farabi petrochemical unit in Iran as well as reported data in the literature for a pilot plate. The comparisons are satisfactory. The effects of some operating parameters including reactor length, feed temperature, reactor pressure, and existence of an inert in the catalytic bed are investigated. The optimum value of each parameter is determined on the basis of the corresponding operating conditions.

Enhanced Reactor Performance with Pressure and Vacuum Swing Reaction

2004 ◽  
Vol 2 (1) ◽  
Author(s):  
Vincent G Gomes
Keyword(s):  
Method Of Lines ◽  
Fixed Bed ◽  
Downstream Processing ◽  
Operating Conditions ◽  
Reactor Performance ◽  
Orthogonal Collocation ◽  
The Method Of Lines ◽  
Dynamic Experiments ◽  
Product Separation ◽  
Pressure Swing

Product separation and regeneration of sorbent was accomplished in a novel pressure swing reactor through pressurisation, adsorption, blowdown and purge steps. The switching from sorption to reaction to regeneration was tested in a two bed sorption/reaction apparatus. Models developed for the mass and momentum transfer in the catalyst bed and sorber, were solved using orthogonal collocation within the method of lines. The effects of operating conditions and cycle configurations on performance were assessed. The results from dynamic experiments with propene metathesis to produce ethene and 2-butene in a fixed-bed catalytic reactor were in agreement with model predictions. Both pressure and vacuum swing demonstrated that conversion and product quality can be enhanced by periodic cycling with greater separation obtained with vacuum swing. The separation of products help reduce the downstream processing costs of exit mixtures, enable reactant utilisation by recycling and improve product handling at subsequent stages. The efficacy of the periodic separating reactor in terms of conversion, product purity and recovery were investigated.

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