Autothermal operation of an adiabatic simulated counter current reactor

Zahn, V.; Mangold, Michael; Seidel‐Morgenstern, A.

doi:10.1016/j.ces.2009.06.042

Cited by 10 publications

(8 citation statements)

References 27 publications

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“…The singularities expected in a loop reactor were characterized [45,46] by plotting the domain of frozen rotating patterns in the plane of the inlet temperature vs the switching velocity (V sw /V th , denoted as Flow rate ratio γ in Fig. 5).…”

Section: Slow Switchingmentioning

confidence: 99%

Dynamics and control of loop reactors - a review

Sheintuch

Nekhamkina

2021

Math. Model. Nat. Phenom.

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In loop reactors the system is composed of several reactor units that are organized in a loop and the feeding takes place at one of several ports with switching of the feed port. In its simplest operation a pulse is formed and rotates around it, producing high temperatures which enable combustion of dilute streams. A limiting model with infinite number of units was derived. Rotating pulses, steady in a moving coordinate, emerge in both models when the switching to front propagation velocities ~1. But this behavior exists over a narrow domain. Simulations were conducted with generic first order Arrhenius kinetics. Experimental observations are reviewed. Outside the narrow frozen rotating pattern domain the system may exhibit multi- or quasi-periodic operation separated by domains of inactive reaction. The bifurcation set incorporates many 'finger'-like domains of complex frequency-locked solutions that allow to extend the operation domain with higher feed temperatures. Control is necessary to attain stable simple rotating frozen pattern within the narrow domains of active operation. Various tested control approaches are reviewed. Actual implementation of combustion in LR will involve several reactants of different ignition temperatures. Design and control should be aimed at producing locked fronts and avoid extinction of slower reactions.

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Section: Slow Switchingmentioning

confidence: 99%

Dynamics and control of loop reactors - a review

Sheintuch

Nekhamkina

2021

Math. Model. Nat. Phenom.

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“…The domain of operation becomes narrower with decreasing feed concentration (or DT a ) and forms a U-or Vshaped domain in the (DT a ,m sw ) plane. [3][4][5][6][7][23][24][25][26][27][28] The boundaries of the operating domain have been approximated: e.g., the lower-switching boundary is approximated by the front propagation velocity (m fr ) which, in an adiabatic reactor, can be determined by system (1), (2) with T m as a parameter, the upper-switching boundary of a quasi-frozen patterns corresponds to v sw 5 v th . The great advantage of operating a LR, when compared to a once-through reactor, is demonstrated in comparing the smallest concentration required to sustain the system (DT lim ) with that at the lower boundary (m sw 5 0) of the operation domain: Methane combustion in a once-through reactor (i.e., m sw 5 0) requires DT a > 1100 K, as opposed to (DT lim )$50 K in a LR with eLem sw /u$1.…”

Section: Introductionmentioning

confidence: 99%

“…The dependence of ΔT lim on the parameters of the adiabatic LR was considered by analysis of the reaction and the extinction front propagation with appropriate matching conditions (loop scheme) by Altimary et al Numerical analysis using an approximate moving bed reactor model and a continuation technique was conducted by Zahn et al Approximations for ΔT lim were not presented by the authors, for nonadiabatic conditions the analytical relations were not published as well.…”

Section: Introductionmentioning

confidence: 99%

“…The operation domain determined for ethylene or for methane oxidation in an uncontrolled system is shown in Figure . The domain of operation becomes narrower with decreasing feed concentration (or ΔT a ) and forms a U‐ or V‐shaped domain in the ( ΔT a ,ν sw ) plane . The boundaries of the operating domain have been approximated: e.g., the lower‐switching boundary is approximated by the front propagation velocity ( ν fr ) which, in an adiabatic reactor, can be determined by system (1), (2) with T m as a parameter, the upper‐switching boundary of a quasi‐frozen patterns corresponds to v sw = v th .…”

Section: Introductionmentioning

confidence: 99%

“…A note about terminology: While we adopted the term “loop reactor” other groups have used the terms “network of reactors” and “simulated moving bed.” The term “chemical loop combustion” refers to forced oxidation and reduction of the catalyst and is different from the present topic.…”

Section: Introductionmentioning

confidence: 99%

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What is the leanest stream to sustain a nonadiabatic loop reactor: Analysis and methane combustion experiments

2016

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While previous studies experimentally demonstrated that loop reactor (LR) can be sustained with a lean feed (using ethylene combustion) and have analyzed the single‐reaction adiabatic case, this work analyzes the effects of heat loss and of reactor size to determine the leanest stream (expressed in terms of adiabatic temperature rise ΔTlim) that will sustain the operation. For an adiabatic infinitely long reactor ΔTlim→0 while for a finite reactor ΔTlim scales as (1 + Pe/4)−1 where Pe = Luρcpf/k, and heat loss increases this limit by (β/Pe)1/2. Thus, a good design of a LR will aim to decrease conductivity (k) and radial heat‐transfer coefficient (β) while increasing throughput (u) and reactor length. This article is also the first experimental demonstration of auto‐thermal operation in a LR for catalytic abatement of low‐concentration of methane, showing the leanest stream to be of 8000 ppm vs. 33,000 ppm in a once‐through reactor. Experimental combustion results of methane and of ethylene are compared with model predictions. © 2016 American Institute of Chemical Engineers AIChE J, 63: 2030–2042, 2017

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Process Simulation of an Adsorption Chiller: True Moving Bed Approximation

Günther¹,

Kunz²,

Stierle³

et al. 2014

Chemie Ingenieur Technik

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Mithilfe von Adsorptionswärmepumpen kann thermische Energie unmittelbar zur Heizung oder Klimatisierung eingesetzt werden. Um Wärmeverluste zu vermeiden wird bei Mehrbett‐Prozessen die für die Desorption benötigte Wärme zwischen den Betten übertragen und so mehrfach genutzt. Da die Auslegung derartiger Prozesse sehr aufwendig ist, ist es sinnvoll, zunächst den theoretischen Grenzfall eines stationären Gegenstromprozesses zu betrachten. Diese True‐Moving‐Bed‐Approximation erlaubt es, sowohl Methoden der Parameterverfolgung zu nutzen als auch Ausgangsgrößen zu spezifizieren.

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Autothermal operation of an adiabatic simulated counter current reactor

Cited by 10 publications

References 27 publications

Dynamics and control of loop reactors - a review

Dynamics and control of loop reactors - a review

What is the leanest stream to sustain a nonadiabatic loop reactor: Analysis and methane combustion experiments

Process Simulation of an Adsorption Chiller: True Moving Bed Approximation

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