Structure characteristics of packed tower

The packing tower is a mass transfer equipment in which the packing in the tower is used as a gas-liquid contact member.The column body of the packing tower is a vertical cylinder with a packing supporting plate at the bottom.A packing clamp shall be installed above the packing to prevent it from being blown by the updraft.Liquid is sprayed onto the packing from the top of the tower through the liquid distributor and left along the packing surface.After the gas is sent from the bottom of the column and distributed by the gas distribution device (generally there is no gas distribution device in the small diameter column), the gas and the liquid flow through the gap of the packing layer continuously in a counter-current manner. On the packing surface, the gas-liquid phase contacts closely for mass transfer.The packed tower is a continuous contact gas-liquid mass transfer device. The composition of the two phases changes continuously along the tower height. Under normal operation, the gas phase is continuous phase and the liquid phase is dispersed phase.

When the liquid flows down along the packing layer, it tends to concentrate gradually towards the column wall, so that the liquid flow near the column wall increases gradually, which is called the wall flow.Wall flow effect results in uneven distribution of gas-liquid phase in the packing layer, thus decreasing mass transfer efficiency.Therefore, when the packing layer is high, it needs to be segmented and a redistribution device is set in the middle.The liquid redistribution device comprises a liquid collector and a liquid redistribution device. The liquid flowing from the upper packing layer is collected by the liquid collector and sent to the liquid redistribution device, which is distributed and sprayed onto the lower packing layer.

The packed column has the advantages of large production capacity, high separation efficiency, small pressure drop, small liquid holding capacity and large operating flexibility.

Packing tower also has some shortcomings, such as high cost of packing;When the liquid load is small, the packing surface can not be effectively wetted, so that the mass transfer efficiency is reduced;Can not be used directly for suspended solids or easily polymerized materials;It is not suitable for complex distillation such as lateral feed and discharge.

Type of packing

There are many types of fillers, which can be divided into bulk packing and structured packing according to different loading methods.

1. Random tower packing

Random tower packing is a certain geometric shape and size of the particle body, generally in a random way stacked in the tower, also known as random packing or granular packing.Bulk packing can be divided into ring packing, saddle packing, ring saddle packing and spherical packing according to its structure.

2. Structured packing

Structured packing is arranged in a certain geometric configuration, neatly stacked packing.There are many kinds of structured packing, according to its geometric structure can be divided into grid packing, corrugated packing, pulse packing and so on.