Simulation of Anaerobic Digesters

What are the benefits of hydrograv simulations?

  • Maximization of the active volume
  • Maximization of the circulation rate
  • Deterministic comparision of variants and optimization of various mixing systems like pumps, screw pumps, agitators or gas injection


Example 1: Measurement and simulation of the actual sludge viscosity to increase the forecasting reliabilty

  • Selection and parameterization of a appropiate rheology model based on laboratory measurements using a viscometer

Figure: Laboratory with measuring technology to determine viscosity (left) and measured viscosity as a function of shear rate and adapted rheology model (right).


Figure:   Simulated dynamic viscosity in a digester with three-bladed agitator.


Example 2: Visualisation of processes

  • Streamlines visualisise the flow path and show areas with hydraulic deficits, e.g. short circuits

  Figure: Streamlines with velocities. 


Example 3: Determination of areas with acitve volume

  • quantitative determination of areas with velocities greater than 1 cm/s

Figure: Visualization and analysis of the active volume in a digester for different geometrical and operational variants.


Example 4: Detailed deterministic analysis of the actual circulation rate

  • Circulation rate as a function of the flow velocity, e.g. as a funcion of the tank height or as volume fraction

Figure: Analysis of the circulation rate along the tank height (left) and als fraction of the total volume (right).