The structure and working principle of the packing tower
The packing tower’s function is for the adsorption application. It is the most important equipment for the chemical, petrochemical and refinery industries.
The packing tower’s structure features as follows:
With internal packing as the mass transferring equipment for the gas- liquid two-phase contact parts in the packing tower. The body of the packing tower is Vertical cylindrical. There is supporting board in the bottom. The packing will be piled randomly or regularly on the supporting board. To avoid being flown updraft, the pressure plate will be installed above the packing. The liquid sprays the packing from the top of tower to the liquid distributor and flow along with the packing surface. The gas is fed from the bottom, go through the gas distribution(small diameter tower usually no gas distribution equipment available), countercurrent to the liquid to pass through the gap of the packing layer, the surface of the packing, gas-liquid two-phase will be in close mass transfer. The packing tower belongs to the continuous contact gas-liquid mass transfer equipment. The two-phase compose the high continuous changes along the height of the tower. Under the normal operation conditions, the gas phase is continuous one, the liquid phase is dispersed.
When the liquid flows down along the packing layer, there is a gradual trend to concentrate the column wall. Such that fluid flow near the column wall increases, this phenomenon known as wall flow. The wall flow effect will make the gas-liquid two-phase uneven distribution in the packing layer, and then the mass transfer effect will be down. On this way, when the packing layer is high, the segmentation will be needed. In the middle of the packing layer needs to be set the redistribution devices. The liquid further distribution equipment includes the liquid collector and liquid redistribution two parts. The upper flow of the packing through the liquid collector to collect the liquid, then fed to the liquid redistributor. Finally spray to the lower packing after the redistribution.
The packing tower has the large capacity, high separation efficiency, low pressure drop, small liquid holdup, flexible operation and other advantages.
Surely the packing tower has some disadvantages as well. Such high cost of the packing; when the liquid load is small, it cannot make the packing surface wet effectively, then the mass transfer effect is lower. Also it cannot be used directly for the suspension or easily polymerizable materials. Also it is not suitable for the complicated distillation with lateral line feeding and discharging and so on.
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