Numeric Simulation‐Based Analysis of the Mixing Process in Anaerobic Digesters of Biogas Plants

Conti, Fosca; Saidi, Abdessamad; Goldbrunner, Markus

doi:10.1002/ceat.201900650

Cited by 5 publications

(9 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…16 m 3 is located in the middle of the tank to take in consideration the support, which sustains roof and membrane. However, the reduction of active volume is assumed to be negligible [10]. Two horizontal propellers are implemented to perform the mixing process.…”

Section: Tank Designmentioning

confidence: 99%

See 1 more Smart Citation

Evaluation Criteria and Benefit Analysis of Mixing Process in Anaerobic Digesters of Biogas Plants

Conti

Saidi

Goldbrunner

2020

Environmental and Climate Technologies

Self Cite

View full text Add to dashboard Cite

A valid method to evaluate decisions of a project proposal is the so-called cost-benefit analysis. Criteria are selected and properly weighted to determine if the project is effective and feasible. The present research study is focused on methodical selection of design parameters to install two propeller mixers inside anaerobic digesters of biogas plants. A cylindrical tank of 1400 m3 was considered. For the model-based optimisation, the substrate was considered as a non-Newtonian fluid with a density of 1090 kg/m3. The Oswald-de Waele power-law model was selected to account for the rheological behaviour of the fluid. Installation parameters of the mixers were rotational angles and heights of the shafts of the two propellers. A computational model was developed to simulate the fluid dynamics depending on the mixing process inside the tank. Several configurations were analysed according to evaluating criteria such as the value of the fluid velocity, its distribution along the three spatial dimensions, and the power consumption to rotate the mixers. The maximum fluid velocity and minimum power consumption were observed when the propellers are located at intermediate height inside the tank and with the shafts perpendicular to the tank radius. With this configuration, the fluid reaches a maximum velocity of 0.28 m/s. According to the investigation, it is evident that mixing systems with propeller shafts deep-seated and parallel to the tank radius should be avoided, both in term of efficiency of the fluid mixing distribution and in term of power consumption.

show abstract

Section: Tank Designmentioning

confidence: 99%

“…On the wall and bottom surface layers of the tank no-slip conditions were adopted, whereas the fluid surface on the top (transition to gas) was modelled with slip conditions [23]. Details of the modelling procedure and CFD setting are presents in [10], [11], [17].…”

Section: Modelling Procedures and Cfd Settingmentioning

confidence: 99%

Evaluation Criteria and Benefit Analysis of Mixing Process in Anaerobic Digesters of Biogas Plants

Conti

Saidi

Goldbrunner

2020

Environmental and Climate Technologies

Self Cite

View full text Add to dashboard Cite

show abstract

“…Additionally, these fluids exact properties that vary from their compositions and other variables, e.g., animal feed. To approximate the fluid's shear-thinning viscosity behavior, the approach of Fosca Conti et al [8] was followed. Thus, for this simulation, the power-law model for the viscosity of Oswald-deWaele was chosen [9].…”

Section: Computational Fluid Dynamicsmentioning

confidence: 99%

Sim-to-Real Transfer in Deep Learning for Agitation Evaluation of Biogas Power Plants

et al. 2023

View full text Add to dashboard Cite

show abstract

“…Very few studies [58][59][60][61][62][63] have been noted in the literature that investigates hydrodynamics in an anaerobic digester under both scale-up and scale-down conditions of an actual biogas plant anaerobic digester. It is noted that the observation of mixing in digesters under real conditions is complex and cost-intensive.…”

Section: Correlation Between Lab-scale and Large-scale Mixing In Anaerobic Digestersmentioning

confidence: 99%

Critical Analysis of Methods Adopted for Evaluation of Mixing Efficiency in an Anaerobic Digester

Singh

Čonka

et al. 2021

Sustainability

View full text Add to dashboard Cite

The effect of slurry mixing in an anaerobic digester on biogas production was intensively studied in the last few years. This subject is still debatable due to fact that this process involves three phases, solid-gas-liquid, along with the involvement of microbes during biochemical reactions, which are highly vulnerable to changes in hydrodynamic shear stresses and mixing conditions. Moreover, the complexity in the direction of optimization of mixing magnifies due to the implication of both fluid mechanics and biochemical engineering to study the effect of mixing in anaerobic digestion (AD). The effect of mixing on AD is explored using recent literature and theoretical analysis, concentrating on the multi-phase and multi-scale aspects of AD. The tools and methods available to experimentally quantify the function of mixing on both the global and local scales are summarized in this study. The major challenge for mixing in an anaerobic digester is to minimize dead zones and maintain uniform distribution of viscosity and shear at low mixing intensities without disrupting the microbial flocs and syntrophic relationships between the bacteria during the AD process. This study is a critical analysis of various techniques and approaches adopted by researchers to evaluate the effectiveness of mixing regimes and mixing equipment. Most studies describe biogas production performance and hydrodynamic characteristics of the digesters separately, but the evaluation of mixing requires interdisciplinary experts, which include mechanical engineers, microbiologists and hydrodynamic experts. Through this review, the readers will be guided through intensive literature regarding agitation, the best possible way to scrutinize the agitation problems and the approach to answering the question “why is the optimization of mixing in an anaerobic digester still a debatable subject?”.

show abstract

Numeric Simulation‐Based Analysis of the Mixing Process in Anaerobic Digesters of Biogas Plants

Cited by 5 publications

References 25 publications

Evaluation Criteria and Benefit Analysis of Mixing Process in Anaerobic Digesters of Biogas Plants

Evaluation Criteria and Benefit Analysis of Mixing Process in Anaerobic Digesters of Biogas Plants

Sim-to-Real Transfer in Deep Learning for Agitation Evaluation of Biogas Power Plants

Critical Analysis of Methods Adopted for Evaluation of Mixing Efficiency in an Anaerobic Digester

Contact Info

Product

Resources

About