Airlift reactors are submerged reactors in which the energy input is achieved by applying gas. Compressed air is often used as the gas.
During operation compressed air enters the airlift reactor at the bottom through the gas distributor. The added air mixes with the contents of the reactor and rises in the form of air bubbles. The rising air bubbles cause an upward flow. In doing so a portion of the oxygen in the air dissolves in the water. The area with the upward flow is called the riser. The remaining air bubbles leave the water at the top of the reactor. The gas-free liquid is fed back to the bottom section of the reactor in parallel to the riser. The area with the downward flow of an airlift reactor is called the downcomer. During operation the content of the reactor is recirculated through the riser and the downcomer. This recirculation is overlaid by perfusion in continuous operation. An additional tank with feed pump is provided for this purpose. The velocity of the circulation is set by the flow rate of the air.
Learning Objectives and Experiments
- Influence of the superficial gas velocity on:
- Gas content
- Mass transfer coefficient
- Mixing time
- Superficial fluid velocity
Specification
- Determination of important characteristic variables at the airlift reactor
- Transparent airlift reactor with external recirculation
- Compressed air for generation of air bubbles to recirculate the reactor contents
- Adjustment of the superficial gas velocity via a valve and mass flow controller
- Nitrogen to remove the oxygen from the reactor content
- Determination of the superficial liquid velocity via the conductivity
- Determination of the mixing time with indicator and colour change method
- Sensors for measuring the conductivity, oxygen content, pressure and flow rate
Technical data
- Airlift reactor
- riser: Ø 180mm
- downcomer: Ø 60mm
- height: 2000mm
- Measuring ranges
- conductivity: 4x 0…100mS/cm
- oxygen concentration: 2x 0…10mg/L
- pressure: 0…3bar
flow rate:
- 0,06…3m3/h (water)
- 1…10m3/h (gas)
- 230V, 50Hz, 1 phase
- 230V, 60Hz, 1 phase; 120V, 60Hz, 1 phase
