1. The general principle of packing tower type selection:
The tower packing is the core component of the packed tower. It provides an effective phase interface for the heat and mass transfer between the gas and liquid phases. Only the tower packing with excellent performance and ideal tower internals can constitute a technically advanced packed tower. .
Packed towers are preferred in the following situations:
In the case of high separation requirements, because some new packings have high mass transfer efficiency, new packings can be used to reduce the height of the tower;
For the distillation and separation of heat-sensitive materials, because the liquid holding capacity of the new packing is small and the pressure drop is small, the packed tower under vacuum operation can be preferred;
For corrosive materials, a packed tower can be selected. Because the packed tower can use non-metallic materials, such as ceramics, plastics, etc.;
For materials that are easy to foam, a packed tower should be used.
2. Selection of packed tower packing:
The geometric characteristic data of packing mainly include specific surface area, void ratio, packing factor, etc., which are the basic parameters for evaluating the performance of packing.
① Specific surface area
The filler surface area per unit volume of filler is called the specific surface area, expressed as a, and its unit is m2/m3. The larger the specific surface area of the filler, the larger the gas-liquid mass transfer area provided. Therefore, the specific surface area is an important indicator for evaluating the performance of fillers.
② porosity
The void volume per unit volume of filler is called void ratio, expressed in ε, and its unit is m3/m3, or expressed in %. The greater the porosity of the packing, the greater the ability of gas to pass through and the lower the pressure. Therefore, the porosity is another important index to evaluate the performance of fillers.
③ Filling factor
The ratio of the specific surface area of the filler to the cube of the void ratio, that is, a∕ε3, is called the filler factor, expressed in Ф, and its unit is 1/m. It represents the hydrodynamic properties of the filler, and the smaller the Ф value, the smaller the flow resistance.
3. The performance of packing is usually measured according to the three elements of efficiency, flux and pressure drop.
Under the same operating conditions, the larger the specific surface area of the filler, the more uniform the gas-liquid distribution, the better the wettability of the surface, and the higher the mass transfer efficiency;
