Dead space interaction in continuous stirred tank reactors

Due to the importance of gas-phase chemical reaction kinetics in low-emission combustion, stirred tank reactors have been used for decades as an experimental tool to study high- and low-temperature oxidation. A Jet-Stirred Reactor (JSR) setup is valuable to determine the evolution of species mole fractions. For the accuracy of the experimental results, it is important that a JSR is designed such that the concentration field is as homogeneous as possible in order to avoid disturbance of the chemical kinetics. In this work, numerical simulations were performed to investigate the mixing in a JSR chamber. The turbulent structures inside the JSR and the nozzles are captured using Large Eddy Simulations. We conducted numerically a parametric study to evaluate the effects of thermodynamic conditions and geometrical parameters on the mixing characteristics. More specifically, the diameter of the spherical chamber is modified together with the diameter of the nozzles through which fresh gases are fed. The characterization of the gas flow inside a typical spherical JSR layout and results derived by the normalized standard deviation of a tracer mass fraction show that a reduction of the JSR diameter at high pressures improves the homogeneity. Further, we propose a new optimized configuration consisting of six nozzles pointing to the center of the reactor which provides a more uniform composition compared to the standard JSR design.

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“…12. In the dead regions a very small exchange of material happens inside the reactor with insufficient molecular mixing [41].…”

Section: Parametric Investigation Of the Geometrical Parametersmentioning

confidence: 99%

Parametrical investigation for the optimization of spherical jet-stirred reactors design using large eddy simulations

et al. 2021

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“…If any transfer of material takes place in and out of dead spaces, the plot of In [1 -F(t)] against r/r R no longer yields a straight line as the emergence of the dried solids at the outlet is slowed down. 6 The foregoing expressions may be extended to the situation where the material streams through a succession of continuously worked units. When the residence time in each stage is the same, the cumulative-fraction F(r) becomes <7) *>-'-2 ( Ä (9.16) for an «-staged dryer should perfect mixing occur.…”

Section: O X ° Jmentioning

confidence: 99%

Continuous Drying

Keey

1972

Drying

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“…Each compartment is modelled as a continuously stirred tank reactor. This widely used approach was introduced by Corrigan and Beavers [3]. It was independently introduced by Kumpinsky & Epstein to investigate the effects of incomplete mixing transitions in bistable systems [14] and latter used by Ganapathisubramanian to investigate the iodate-As(III) system [7,8].…”

Section: Introductionmentioning

confidence: 99%

Quadratic autocatalysis with non-linear decay. II: the effect of incomplete mixing

2019

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Isothermal kinetic models based upon quadratic and cubic autocatalysis have been widely investigated as model schemes for a variety of chemical systems. A standard assumption in such models is that the process is being investigated in a continuously fed well-stirred tank reactor. This allows the mathematical model to be idealised as a system of ordinary differential equations. In this paper we relax the assumption that the reactor is well-mixed and employ an established two-parameter model for incomplete mixing. We use this to investigate the consequences of poor mixing upon the static and dynamic multiplicity of the model. We show that the phenomenon of incomplete mixing can reduce the complexity of the steady-state diagram by removing Hopf and limit-point bifurcations from the system. Incomplete mixing may also increase the complexity of the steady-state diagram through the creation of additional Hopf bifurcation points.

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Dead space interaction in continuous stirred tank reactors

Cited by 9 publications

References 2 publications

Parametrical investigation for the optimization of spherical jet-stirred reactors design using large eddy simulations

Parametrical investigation for the optimization of spherical jet-stirred reactors design using large eddy simulations

Continuous Drying

Quadratic autocatalysis with non-linear decay. II: the effect of incomplete mixing

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