Analysis of reduction stage of chemical looping packed bed reactor based on the reaction front distribution

Hua, Xiuning; Wang, Wei; Hu, Yue; Zhu, Jin

doi:10.1007/s10163-014-0260-z

Cited by 9 publications

(5 citation statements)

References 27 publications

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“…33,34 The simulation validates that in an equilibrium system, with CH 4 or CO as the fuel gas, the CO relative mole fraction follows the same rule when only CO and CO 2 are taken into account. This is also true for H previous study, 35 when CO was used as the fuel gas, there were thermodynamic limitations for CO and CO 2 , and the gas concentration profile showed four apparent plateaus, which corresponded with the phase equilibrium diagram of the Fe− C−O system. Therefore, the CH 4 -fueled system might follow the equilibrium phase diagram of the Fe−C−O system.…”

Section: Resultssupporting

confidence: 76%

“…This is also true for H 2 /H 2 O when comparing the CH 4 - and H 2 -fueled systems. In our previous study, when CO was used as the fuel gas, there were thermodynamic limitations for CO and CO 2 , and the gas concentration profile showed four apparent plateaus, which corresponded with the phase equilibrium diagram of the Fe–C–O system. Therefore, the CH 4 -fueled system might follow the equilibrium phase diagram of the Fe–C–O system.…”

Section: Resultsmentioning

confidence: 72%

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Using High/Low WHSV Value to Uncover the Reaction Behavior between Methane and Iron Oxide in Packed Bed for Chemical Looping Hydrogen Generation Process

Turap

Wang

et al. 2020

Ind. Eng. Chem. Res.

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In the chemical looping hydrogen generation (CLHG) system, methane acts as an important reducing gas, whereas iron oxide has poor reactivity with methane, resulting in the inefficiency of the system. Thus, the fundamental reaction behavior between methane and iron oxide is of great importance. In this paper, applying a high/low-weight hourly space velocity technique, the reaction behavior in a dynamically operated packedbed system was investigated based on the outlet gas concentration profiles. As the reduction process proceeded, complete oxidation, partial oxidation, and methane decomposition dominated in sequence. The results also validated that the CO/CO 2 relative mole fractions followed the equilibrium diagrams of the Fe−C−O system. The reaction behavior in the packed-bed reactor was a combination of thermodynamic limitation and the reaction front movement. This study suggested that the deep reduction CLHG technology is suitable for increasing the conversion of CH 4 in the packed-bed system.

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Section: Resultssupporting

confidence: 76%

Section: Resultsmentioning

confidence: 72%

Using High/Low WHSV Value to Uncover the Reaction Behavior between Methane and Iron Oxide in Packed Bed for Chemical Looping Hydrogen Generation Process

Turap

Wang

et al. 2020

Ind. Eng. Chem. Res.

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“…This result demonstrates that the reaction fronts movement proposed based on the temporal and spatial variation of the axial solid conversion in the packed bed can be used to explain the changes of the outlet gas concentration from the packed bed well. A similar phenomenon was also found in our previous work[57]. Breakthrough curve for iron (III) oxide reduction by 85% CO in CO2 at 900 °C in the non-steady state packed bed (a), and the comparison between the calculated solid conversions of the whole bed based on the breakthrough curve and the results from sub-layer experiments with an error analysis (b).…”

supporting

confidence: 82%

“…That is, the movement of the reaction fronts will definitively affect the behaviour of the packed bed. Hua [57] developed a model of a nonsteady state packed bed for a cyclic system of Fe2O3 to Fe that included three reaction fronts.…”

Section: Introductionmentioning

confidence: 99%

The behaviour of multiple reaction fronts during iron (III) oxide reduction in a non-steady state packed bed for chemical looping water splitting

et al. 2017

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Owing to the unclear temporal and spatial variations of axial solid conversion in a packed bed using iron (III) oxide as an oxygen carrier, we directly observe these variations by means of a sub-layer approach. The results indicate that the behaviour of the multiple reaction fronts during iron (III) oxide reduction by CO or H2 within a packed bed for chemical looping water splitting (CLWS) is strongly dependent on the reaction temperature. When the reaction temperature is lower than the merging temperature, three reaction fronts, i.e., Fe2O3-Fe3O4, Fe3O4-Fe0.947O and Fe0.947O-Fe, and three product zones, i.e., Fe3O4, Fe0.947O and Fe, will appear in the packed bed. In contrast, when the reaction temperature is higher than the merging temperature, the Fe2O3-Fe3O4 and Fe3O4-Fe0.947O fronts merge, leading to the disappearance of the Fe3O4 zone. As a result, only the Fe2O3-Fe0.947O and Fe0.947O-Fe fronts, as well as Fe0.947O and Fe zones will appear in the packed bed. These reduction behaviours are verified by two breakthrough curves, one for T < Tm and one for T > Tm, from the thermodynamically controlled reduction of iron (III) oxide in the packed bed. The reaction front movement model, which is proposed based on the reduction behaviour, can be used to determine the maximum solid conversion of the reduction step, i.e., the thermodynamic limitation of the reduction step, in the packed bed CLWS. The maximum solid conversion can reach 0.409 for the CO case and 0.554 for the H2 case. The first discovery of both the behaviours of the reaction fronts movement and the thermodynamic limitations of the reduction step standardizes the criteria for both the oxygen carrier evaluation and the optimization of the operating conditions and provides theoretical support for scaling up the packed bed and developing new technology for packed bed CLWS

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“…Therefore, the application to the industrial processes has not yet been well investigated. In our previous work on the reduction period [36], the conversion of Fe 2 O 3 was beyond 11% when CO was fully converted in a packed bed reactor. The solid i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 4 0 ( 2 0 1 5 ) 1 2 0 9 7 e1 2 1 0 7 conversion did show the potential of oxygen carriers for hydrogen generation when a high fuel conversion was achieved in the reduction period.…”

Section: Introductionmentioning

confidence: 99%

Phase distribution and stepwise kinetics of iron oxides reduction during chemical looping hydrogen generation in a packed bed reactor

Zhu

Wang

Hua

et al. 2015

International Journal of Hydrogen Energy

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Analysis of reduction stage of chemical looping packed bed reactor based on the reaction front distribution

Cited by 9 publications

References 27 publications

Using High/Low WHSV Value to Uncover the Reaction Behavior between Methane and Iron Oxide in Packed Bed for Chemical Looping Hydrogen Generation Process

Using High/Low WHSV Value to Uncover the Reaction Behavior between Methane and Iron Oxide in Packed Bed for Chemical Looping Hydrogen Generation Process

The behaviour of multiple reaction fronts during iron (III) oxide reduction in a non-steady state packed bed for chemical looping water splitting

Phase distribution and stepwise kinetics of iron oxides reduction during chemical looping hydrogen generation in a packed bed reactor

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