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Heavy Oil Recovery
Published in Chun Huh, Hugh Daigle, Valentina Prigiobbe, Maša Prodanović, Practical Nanotechnology for Petroleum Engineers, 2019
Chun Huh, Hugh Daigle, Valentina Prigiobbe, Maša Prodanović
The kinetic model was incorporated into a plug-flow reactor model. This model assumes an isothermal operation where reactions are assumed irreversible of the first-order. The reaction rate for each component i can be expressed by its generic mass balance: dFidV=QdyidV=dyidfalse(V/Qfalse)=dyidτ
Hybrid Modeling of Petrochemical Processes
Published in Jarka Glassey, Moritz von Stosch, Hybrid Modeling in Process Industries, 2018
Qi et al. (1999) compared predictions from a two-dimensional reactor model with a hybrid reactor model that employed a simple plug-flow reactor model as its mechanistic (first principles) part. It is well known that for highly exothermic reactions, a simple plug-flow model cannot predict accurately the performance of the reactor, due to incorrect heat transfer representation. Qi and coworkers employed a three-layer feed-forward neural network (see UFLDL tutorial on multilayered neural networks) to estimate the overall heat transfer parameters, which were then used in the plug-flow reactor model. The structure of the hybrid model is shown in Figure 6.4. Both steady-state and dynamic hybrid reactor models were developed. Their predictions were compared (see Table 6.1) to the predictions of the two-dimensional rigorous model and to the experimental data in Figure 6.5 (steady state) and Figure 6.6 (dynamic). Clearly, the hybrid model predictions are as accurate as the predictions from the two-dimensional model. At the same time, the hybrid model requires much shorter computational times, which make it much more suitable for on-line optimization and control applications.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
A complete isothermal plug flow reactor model can readily be constructed using as many Equations (80.10) as there are components k, and as many kinetic models as there are reactions j. For nonisothermal reactors, differential equations that describe the temperature changes down the length of the reactor can be constructed in an analogous fashion, using the molar heat generation for each reaction j and its corresponding reaction rate rj and heat transfer terms appropriate to the reactor type and geometry. For a multitube plug flow reactor with coolant on the outside of the tubes, the equation for reaction temperature (in degrees/volume) is as follows: dTrdVe=∑1nrrjΔHj-4UDtTr-TcFeρpcp
Auto-Ignition and Numerical Analysis on High-Pressure Combustion of Premixed Methane-Air mixtures in Highly Preheated and Diluted Environment
Published in Combustion Science and Technology, 2022
Subrat Garnayak, Ayman M Elbaz, Olawole Kuti, Sukanta Kumar Dash, William L Roberts, V. Mahendra Reddy
In the present study, numerical simulation of a steady, one-dimensional, constant pressure laminar premixed flame in highly preheated and diluted conditions was conducted using the adiabatic plug flow reactor model (PFR) module Ansys Chemkin Pro and GRI 3.0 chemistry. The plug flow reactor model is computationally efficient since it solves first-order ordinary differential equations (ODEs) of continuity, momentum, energy, and species without requiring transport properties. The fundamental assumption of the plug flow reactor model is that the fluid is perfectly mixed in the radial direction, while there is no mixing in the axial direction. This work considers the domain of length 1.4 m and diameter of 0.01 m, in which the combustion of laminar premixed CH4/O2/N2 mixture in a diluted and at high-pressure condition is analyzed. The reactor’s dimensions were taken from the experimental tubular reactor used by Sabia et al. (2013). A stoichiometric premixed mixture (ϕ = 1) of CH4 and oxidizer (O2 and N2) was considered, with different O2 dilution levels. Reactants were supplied to the inlet at different reactant temperatures ranging from 1100 to 1500 K. The percentage of O2 in the air was varied from 21% to 3%. The pressure of the reactor was varied from 1 to 10 atm. The calculated jet Reynolds number of the mixture for all cases covered was ≈ 1750. The effect of all these parameters (%O2, combustor pressure, inlet temperature) on achieving distributed combustion is investigated in this work. At the combustor inlet, the mass flow inlet boundary condition was applied with a constant mixture mass flow rate of 0.00061 kg/s for all the cases here. The mixture’s mass flow rate was calculated by considering the inlet velocity of 30 m/s as the base case for the reactant temperature of 1300 K, and at a pressure of 1 atm with a 21% O2 level. The operating conditions considered in the present work (as well as the corresponding flow velocity under stoichiometric conditions for all cases) are supplied in Table S1 of the supplementary material. Similarly, the mole fractions of the mixture species (CH4, O2, and N2) provided at the inlet with different dilution levels for ϕ = 1 are listed in Table 1.