Comparative evaluation of spherical radial flow reactor, spherical axial flow reactor, and tubular reactor in ammonia production by using CFD simulation

Nikzad, Amin; Iranshahi, Davood; Ranjbaran, Mohammad

doi:10.1016/j.fuel.2023.128772

Cited by 6 publications

(5 citation statements)

References 46 publications

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“…The residence time of the entire green ammonia synthesis system ranges from 10 s to 10 min, approximately, , depending on factors including the process topology, detailed structures of the apparatus, and production loads. To preserve possible causal relationships and time delays to the greatest extent possible, the range of the time delay for the system is set to [−10 min, 10 min].…”

Section: Methodsmentioning

confidence: 99%

Causality Analysis of the Green Ammonia Synthesis Process Using the Convergent Cross Mapping Algorithm

Yang,

Li,

Zhang

et al. 2024

Ind. Eng. Chem. Res.

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Ammonia synthesis has been gradually altered from the gray process (using fossil fuels as hydrogen sources) to the green process (directly or indirectly using water electrolytic cells as hydrogen sources powered by renewable energy), with the motivation of sustainable development and carbon neutrality. The fluctuating nature of renewable energy and the location mismatch between power plants and the production complex make gray ammonia production roadmaps likely to fail or embrace the change. Establishing knowledge graphs in the form of causal relationship network diagrams will help enterprise decision-makers and engineers better understand the process and generate correct production operations and scheduling. In this study, a chemical engineeringinformed method is introduced to generate causal networks of multiple load conditions for green ammonia production. Expert knowledge of chemical engineering is embedded in the determination of the existence and corresponding time delay of the causal relationships of variable pairs. In an industrial case study, the skeletal knowledge graphs and evolution of the control mechanisms were identified in a comparison of the derived causal networks. Extended applications are expected with further integration of controlling theory and algorithms.

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Section: Methodsmentioning

confidence: 99%

Causality Analysis of the Green Ammonia Synthesis Process Using the Convergent Cross Mapping Algorithm

Yang,

Li,

Zhang

et al. 2024

Ind. Eng. Chem. Res.

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show abstract

“…In the simulation calculation, the green ammonia synthesis process is regarded as a steady state process, and the operating parameters of the reactor, such as pressure, temperature and flow rate will remain constant …”

Section: Case Studymentioning

confidence: 99%

“…(1) In the simulation calculation, the green ammonia synthesis process is regarded as a steady state process, and the operating parameters of the reactor, such as pressure, temperature and flow rate will remain constant. 18 (2) The model regards N 2 and H 2 as an ideal gas mixture under high temperature and pressure. The mixing law follows the equation of state of the ideal gas, and the mass diffusion follows the molecular kinetic theory.…”

Section: Case Studymentioning

confidence: 99%

“…Given the reactor’s intricate internal structure and the nonuniform reactions within the catalyst beds, this partial heterogeneity marginally impacts the overall reaction efficacy but notably extends the iteration computation time. Hence, the study simplifies the reactor’s physical model for numerical simulations, adopting the following assumptions: In the simulation calculation, the green ammonia synthesis process is regarded as a steady state process, and the operating parameters of the reactor, such as pressure, temperature and flow rate will remain constant The model regards N 2 and H 2 as an ideal gas mixture under high temperature and pressure.…”

Section: Case Studymentioning

confidence: 99%

“…There are few studies on the CFD modeling of green ammonia reactors. Nikzad et al 18 analyzed and compared three configurations of the packed bed reactor for ammonia synthesis by computational fluid dynamics simulation and simultaneously solving the mass, energy, and momentum conservation problems in two-dimensional geometry. However, the model they proposed was still two-dimensional and had not been applied to study the impact at varying production loads.…”

Section: Introductionmentioning

confidence: 99%

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How to Achieve Flexible Green Ammonia Production: Insights via Three-Dimensional Computational Fluid Dynamics Simulation

Zhang,

Li,

Zhou

et al. 2024

Ind. Eng. Chem. Res.

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The green ammonia synthesis process involves producing ammonia using hydrogen obtained from electrolyzing water with renewable energy sources, thereby contributing to carbon emission reduction and promoting sustainable development. However, in large-scale commercial operations, there exists a contradiction between the volatility of renewable energy and the stability required in chemical production processes: the fluctuation of the power supply and feedstocks constantly brings new changes to the heat and mass transfer of the fluid in the reactor, which will pose a severe challenge to the flexibility of reactor operation. In this study, we utilized a combination of reaction kinetics and computational fluid dynamics (CFD) to conduct three-dimensional modeling of the green ammonia reactor with validation against industrial data. The proposed novel approach facilitated the prediction of spatial flow field distribution within the reactor and assessment of varying load impacts on green ammonia yield and production index. The results indicate minimal deviation in processing parameters from baseline operating conditions under varying loads, yet a notable reduction in green ammonia yield occurs with decreased production loads, nearly reducing by 50%. Through the sensitivity analysis, the optimal operation scheme under different production loads is proposed. For example, at 30% load, the optimal operating pressure and hydrogen/nitrogen ratio are 14 MPa and 3.1, which are quite different from the baseline operating conditions. However, such process flexibility comes at the expense of catalyst and energy utilization, decreasing exergy efficiency by approximately 30% and potentially leading to operational anomalies such as gas dead spaces, low-temperature zones, and backflow, underscoring the trade-offs inherent in enhancing process flexibility. Nonetheless, the application potential of the green ammonia flexible synthesis process remains promising. Our proposed three-dimensional reactor simulation offers theoretical underpinnings for ensuring stability and optimal operation regulation in green ammonia production.

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Microreactors with multivariate external force field used for the chemical process intensification

Ma,

Zhao,

Tang

et al. 2024

Chemical Engineering Journal

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Comparative evaluation of spherical radial flow reactor, spherical axial flow reactor, and tubular reactor in ammonia production by using CFD simulation

Cited by 6 publications

References 46 publications

Causality Analysis of the Green Ammonia Synthesis Process Using the Convergent Cross Mapping Algorithm

Causality Analysis of the Green Ammonia Synthesis Process Using the Convergent Cross Mapping Algorithm

How to Achieve Flexible Green Ammonia Production: Insights via Three-Dimensional Computational Fluid Dynamics Simulation

Microreactors with multivariate external force field used for the chemical process intensification

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