Chapter 4
Dynamic Simulation of Technical
Precipitation Processes
Hendrik Rehage and Matthias Kind
Abstract Precipitation of sparingly soluble salts is a widely applied industrial unit
operation to produce color pigments or nutritional additives. Simulation of this unit
operation on a flowsheet level would be a useful tool to simplify process development and optimization. However, the numerical effort of simulating the industrial
standard apparatus for precipitation, the stirred-tank reactor (STR), is generally too
high for process flowsheet simulation. This high computational cost is due mostly to
the complex coupling of mixing and solids formation and the inhomogeneous reaction environment in STRs. Handling of this multiscale challenge in a short time scale,
thus, requires the development of numerically efficient short-cut surrogate models.
In this chapter, we provide an overview of the results from of our project aiming to
develop a dynamic precipitation model for flowsheet simulation using the example of
semi-batch precipitation of barium sulfate. This chapter covers the full development
progress with step-by-step increasing complexity from steady-state to semi-batch
process scale. Multiple experimental setups are used to proof the model hypotheses. The steady-state and dynamic semi-batch precipitation model are exemplarily
implemented in the flowsheet framework Dyssol. By using these flowsheet units, the
specific process dynamics of semi-batch precipitation processes is investigated. It is,
furthermore, demonstrated that using dynamic process parameters (e.g. increasing
impeller rotational speed) might be a suitable method to optimize the product particle
size distribution (PSD) for semi-batch precipitations in the future.
Nomenclature
B
Nucleation rate [m
−4 s
−1
]
B T
Baffles size [m]
C T
Stirrer off-bottom clearance [m]
˜
c
Molar concentration [mol
1 m
−3
]
H. Rehage · M. Kind (B)
Institute of Thermal Process Engineering, Karlsruhe Institute of Technology, Karlsruhe
Kaiserstraße 12, 76131, Germany
e-mail: matthias.kind@kit.edu
© Springer Nature Switzerland AG 2020
S. Heinrich (ed.), Dynamic Flowsheet Simulation of Solids Processes,
https://doi.org/10.1007/978-3-030-45168-4_4
109
Dynamic Simulation of Technical
Precipitation Processes
Hendrik Rehage and Matthias Kind
Abstract Precipitation of sparingly soluble salts is a widely applied industrial unit
operation to produce color pigments or nutritional additives. Simulation of this unit
operation on a flowsheet level would be a useful tool to simplify process development and optimization. However, the numerical effort of simulating the industrial
standard apparatus for precipitation, the stirred-tank reactor (STR), is generally too
high for process flowsheet simulation. This high computational cost is due mostly to
the complex coupling of mixing and solids formation and the inhomogeneous reaction environment in STRs. Handling of this multiscale challenge in a short time scale,
thus, requires the development of numerically efficient short-cut surrogate models.
In this chapter, we provide an overview of the results from of our project aiming to
develop a dynamic precipitation model for flowsheet simulation using the example of
semi-batch precipitation of barium sulfate. This chapter covers the full development
progress with step-by-step increasing complexity from steady-state to semi-batch
process scale. Multiple experimental setups are used to proof the model hypotheses. The steady-state and dynamic semi-batch precipitation model are exemplarily
implemented in the flowsheet framework Dyssol. By using these flowsheet units, the
specific process dynamics of semi-batch precipitation processes is investigated. It is,
furthermore, demonstrated that using dynamic process parameters (e.g. increasing
impeller rotational speed) might be a suitable method to optimize the product particle
size distribution (PSD) for semi-batch precipitations in the future.
Nomenclature
B
Nucleation rate [m
−4 s
−1
]
B T
Baffles size [m]
C T
Stirrer off-bottom clearance [m]
˜
c
Molar concentration [mol
1 m
−3
]
H. Rehage · M. Kind (B)
Institute of Thermal Process Engineering, Karlsruhe Institute of Technology, Karlsruhe
Kaiserstraße 12, 76131, Germany
e-mail: matthias.kind@kit.edu
© Springer Nature Switzerland AG 2020
S. Heinrich (ed.), Dynamic Flowsheet Simulation of Solids Processes,
https://doi.org/10.1007/978-3-030-45168-4_4
109