Plastic Tower Packing: Performance Characteristics And Applications

Plastic tower packing is a widely used random or structured filling material in chemical separation processes, primarily manufactured from polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), and polyvinylidene fluoride (PVDF). Its advantages include low density (PP density approx. 0.90–0.92 g/cm³), high corrosion resistance (suitable for most acids, alkalis, and organic solvents), and significantly lower manufacturing cost compared to metal or ceramic packing. The operating temperature of plastic packing generally does not exceed 100°C (PP) to 150°C (PVDF), and it is suitable for atmospheric and low-pressure conditions.

Typical plastic tower packings include Pall rings, cascade rings, Intalox saddles, and snowflake rings. For a Φ25 mm Pall ring made of PP, the specific surface area is approximately 200–220 m²/m³, void fraction reaches 90%–92%, and bulk density is about 75–85 kg/m³. Due to structural optimization, cascade rings exhibit 20%–30% lower pressure drop and 10%–15% higher mass transfer efficiency compared to Pall rings. These parameters directly affect gas-liquid distribution and mass transfer performance within the column, and hydraulic calculations must be performed based on specific process loads during design.

This packing is widely used in unit operations such as absorption, desorption, distillation, and scrubbing, covering industries including chemicals, petroleum refining, environmental waste gas treatment, and hydrometallurgy. For example, in an HCl tail gas absorption tower, PP plastic packing can withstand 30% hydrochloric acid solution at 80°C with a service life exceeding five years. It should be noted that plastic packing is not resistant to strongly oxidizing media (e.g., concentrated nitric acid, oleum) and is prone to creep or softening at elevated temperatures. Complete data on medium temperature, concentration, and pH value must be provided during selection.

In summary, plastic tower packing offers significant competitiveness in low-to-medium temperature, non-oxidizing gas-liquid mass transfer applications due to its light weight, corrosion resistance, and economic efficiency. However, its upper temperature limit and compressive strength (typically below 0.5 MPa) restrict its use in high-temperature or high-pressure cryogenic conditions. Users should determine the optimal specification by combining process parameters with the packing supplier’s hydrodynamic curves (e.g., pressure drop – loading point – flooding point diagram) to balance capacity and separation efficiency.