How to choose the type of structured packing

The selection of structured packing needs to consider the process requirements, material characteristics and economy, the specific steps are as follows:

First, clear process requirements

Separation efficiency and flux

Specific surface area (such as 125, 150, 250, etc.) is the key parameter, the larger the specific surface area, the higher the mass transfer efficiency, but the resistance will also increase by 12. The efficiency and flux need to be balanced according to separation requirements (such as rectification and absorption). For example, select a high specific surface area packing for scenarios with high separation requirements, but reduce the specific surface area 35 for scenarios that are sensitive to pressure drop.

Operating condition

Consider the temperature (such as plastic packing temperature ≤100℃, metal packing can withstand high temperature and high pressure), pressure and corrosion (such as Cl⁻ corrosion need to choose stainless steel or titanium) 136.

Second, choose the material

Ceramic packing

Corrosion-resistant, heat-resistant, but brittle and fragile, suitable for gas absorption, washing and other scenario13.

Metal packing

Carbon steel: Low cost, suitable for non-corrosive or low corrosion system13.

Stainless steel: strong corrosion resistance, but pay attention to the surface wettability, suitable for most industrial scenario13.

Titanium/special alloy: only for strong corrosive environment (such as strong acid, alkali) 13.

Plastic packing

Corrosion resistance, light weight and low price, suitable for low pressure drop scenarios (such as absorption, extraction), but the surface wettability is poor, can be improved by surface treatment 136.

Third, determine the specifications

Specific surface area selection

In the same type of packings, the larger the specific surface area, the higher the efficiency, but the resistance, flux and cost need to be combined with comprehensive evaluation. For example, Raschig's Supekpak300 has a specific surface area of 300m²/m³ and a 33% reduction in pressure loss12.

Structure type

Corrugated type: high mass transfer efficiency (such as BX, CY type), pressure reduction 6.

Plate type: such as Montz-PakA300 type, plate thickness is only 0.05mm, suitable for high separation requirements 12.

Mesh type: such as Japan's Mitsubishi Mc-pak wire mesh packing, the specific surface area can reach 1000m²/m³12.

Fourth, flexible design

Mixed use

Different sizes or types of packings (e.g., structured + bulk) can be mixed in the same column, or different packings can be used regionally to optimize performance-125.

Economic evaluation

Comprehensive equipment investment, packing costs and operating expenses, such as plastic packing processing capacity is 20%-25% higher than similar, and mass transfer efficiency is 50% higher.

5. Application examples

Refinery: BSH packing (specific surface area 500m²/m³) for crude distillation tower, theoretical plate number is high and the pressure is reduced by 12.

Environmental protection field: Plastic structured packing is used for waste gas treatment, taking into account corrosion resistance and low pressure drop 46.

Through the above steps, the suitable structured packing can be systematically selected to achieve the balance between technical performance and economy.