Monitoring gradient formation in a jet aerated bioreactor

Area of Science:

• Chemical Engineering
• Biochemical Engineering
• Reactor Design

Background:

• Jet aerated loop reactors (JLRs) are known for high mass transfer coefficients (k_La), surpassing stirred tank reactors (STRs) due to higher local power inputs.
• Efficient macromixing is essential in JLRs operating at high local turnover rates to prevent inhomogeneities that decrease reaction selectivity and yields.

Purpose of the Study:

• To investigate the balance between mixing and mass transfer in JLRs.
• To assess the impact of reactor design modifications and medium viscosity on JLR performance.

Main Methods:

• Monitoring dissolved oxygen levels to detect gradients during steady sodium sulfite feed.
• Comparing mixing times and oxygen distribution in JLRs with and without a draft tube against an STR.
• Evaluating the effect of increased medium viscosities on JLR performance.

Main Results:

• Gradients in dissolved oxygen were observed in the JLR, indicating inhomogeneities.
• JLRs showed prolonged mixing times compared to STRs at identical power and aeration rates.
• A draft tube improved oxygen distribution but did not reduce mixing time.
• Increased medium viscosity eliminated gradient formation but significantly altered mass transfer and mixing.

Conclusions:

• The balance between mixing and mass transfer is a critical design aspect for JLRs.
• Reactor design (e.g., draft tube) and operating conditions (e.g., medium viscosity) significantly influence JLR performance.
• Further optimization is needed to ensure efficient and homogeneous operation of JLRs for intensified processes.