Why is structured packing not easy to flood

The reasons why structured packing is not easy to flood are mainly closely related to its structural design and fluid dynamic characteristics, which can be summarized as follows:

1. Optimized structure, uniform flow

Regular geometry: The regular packing (such as corrugated plate, grid plate, saddle ring, etc.) has a regular arrangement and directional flow channel, and the gas and liquid flow in the tower is laminar or stable turbulent flow, reducing the formation of vortices and dead angles.

Uniform distribution: When the liquid passes through the packing surface, it can flow evenly along a specific path (such as corrugated grooves) to avoid local liquid accumulation; The gas rises through vertical or inclined channels, and the gas-liquid contact interface is stable.

2. High specific surface area and low liquid holdup

Efficient mass transfer: The specific surface area of the structured packing is large (up to 200~600 m²/m³), the gas-liquid contact is sufficient, and the mass transfer can be completed under a low gas-liquid load, reducing the risk of liquid flooding caused by overload.

Low liquid retention: Its structural design makes it easy for the liquid to slip off the surface of the filler (such as the inclination of the ripple), and the liquid holdup (the amount of liquid retention in the filler gap) is significantly lower than that of the bulk filler, reducing the possibility of the liquid being ensnaxed by gas.

3. Low pressure drop and wide operating range

Low pressure drop characteristics: The porosity of the structured packing is high (about 80% to 95%), and the gas resistance is small, allowing high gas speed operation without excessive pressure drop, thus extending the operating elastic range.

Anti-clogging ability: The regular structure reduces the clogging caused by fibrous substances or impurities and maintains a stable gas-liquid flow.

4. Increase of flooding critical point

Critical gas velocity control: The hydromechanical model of the structured packing of Hengerwo chemical industry shows that its critical gas velocity (gas velocity causing liquid flooding) is high. For example, the critical gas velocity of corrugated plates is 30% to 50% higher than that of bulk fillers, because its structure guides the gas flow in a layered mode, inhibiting droplet formation and entrain.

Pre-wetting characteristics: Some structured fillers (such as structured saddle rings) need to be pre-wetted to achieve the best performance, at which time the liquid forms a uniform film on the surface of the filler, further improving the gas-liquid separation efficiency.

5. Industrial application verification

Practical case: In large rectification towers (such as ethylene cracking units), the operational stability of structured packed towers is much better than that of bulk packed towers. For example, after a petrochemical enterprise adopts regular corrugated packing, the tower pressure drop is reduced by 40%, the maximum processing capacity is increased by 25%, and no liquid flooding phenomenon occurs.

Sum up

Through structural design, the structured packing can realize the order of gas-liquid flow, the improvement of mass transfer efficiency and the optimization of operating conditions, thus significantly improving the anti-flooding ability. Its advantages are particularly obvious when dealing with high viscosity liquids, foaming systems or heavy load conditions. However, in practical applications, it is still necessary to design reasonably in combination with process parameters (such as gas velocity, reflux ratio) and filler types provided by Hengerwo Chemical (such as the difference between X-ripple and Y-ripple).