Motivation

• Scale up & design of bubble column reactors is still challenging
• Most relevant is the specific interfacial area for mass transfer but it is difficult to estimate
• Models to predict the specific interfacial area are rare due to the lack of measuring techniques and simulation tools
• Laboratory experiments with process medium and operation conditions are time and cost intensive

Objective

• Identification of parameters with biggest impact on mass transfer
• Development of advanced measurement methods for process medium and operation conditions
• Smart design strategy for bubble column reactors with reliable multiscale modeling

Experimental Setup

• Setup 1: DN100 bubble column reactor for process medium & ambient conditions
• Setup 2: High pressure cell for process medium & high pressure conditions
• Setup 3: Pilot plant for process medium & original process conditions
• Setup 4: Characterization of swarm

• Endoscopic Bubble Image Velocimetry (EBIV) for measurements of bubble size distribution & bubble absolute velocity
• Endoscopic Particle Image Velocimetry (EPIV) for measurements of liquid velocity and turbulence data
• Electro-Optical Probe for measurements of local gas holdup

Results

For benchmark system Cumene/Nitrogen:

• Influence of material system on bubble size distribution needs to be taken into account (deviation approx. 10%)

• No significant influence of pressure on bubble size distribution

• Models for bubble velocity are of acceptable accuracy
• Interfacial area needs to be considered depending on a spherical bubble shape (deviation approx. 15%)
• Interfacial area needs to be considered in relation to different gas holdup in compartments (deviation approx. 30%)

Summary & Outlook

Smart scale up & design strategy according to Fig. 2 assisted by
laboratory experiments:

1. Measurement in process medium at ambient conditions
   • Bubble size distribution and bubble shape (eccentricity)
   • Bubble rising velocity (relative swarm velocity)
   • Local gas holdup equations for each compartment
2. Transfer of data to high pressure conditions by using model
3. Design and scale up with adjusted Sherwood correlation
4. One-point EBIV reference measurement on industrial scale for validation and improvement
5. Outlook: Validation of method with different process media