Design of Tower Internals

 Tower internals include liquid distribution device, bed fixing device or bed compression device, packing support device, liquid collection and redistribution and feeding device and gas distribution device. A good performance of a large packed tower, the high performance of the packing itself is important, but with the matching tower parts, especially the liquid distributor and gas distributor is also critical. Otherwise the high performance of the packing can not be fully realized, especially for large diameter, multi-side line, shallow bed tower, gas-liquid distribution is often the key to success or failure. Poor liquid distribution may reduce the performance of the packing by 50-70%.

　　Compared with plate towers, packed towers are more unevenly distributed for liquids. The performance of liquid distribution in packed towers and the performance of the packing is largely dependent on the initial distribution of the liquid. Uneven distribution can lead to a reduction in packing efficiency, especially for low pressure drop packings such as gauge packings. Moreover, when the tower has a high packing layer height, high packing specific surface area and high packing efficiency, the negative effect of the uneven distribution of liquid is even greater.

　　Each type of packing has a liquid natural flow distribution ability. When the initial distribution is better than the natural flow distribution, the liquid will gradually become natural flow distribution along the packing down; when the initial distribution is worse, it will also slowly change to the natural flow distribution.Albright proved that the liquid from better than the natural flow distribution to the natural flow distribution than from worse than the natural flow distribution to the natural flow distribution of the transition much faster.

　　Packed tower liquid distributor design is good or bad, directly affect the uniform distribution of liquid. Good liquid distributor should have a uniform distribution of liquid, gas through the free cross-sectional area, resistance, operating flexibility, not easy to block, not easy to cause foam entrainment and foaming, easy to produce and other advantages. At present, the initial distributor and redistributor of liquid research, relatively more, but also more adequate and mature. Now there have been developed a number of Chung form, there are rows of pipe type, tank type, disk type, jet type and so on. Liquid from the distributor out of the form of orifice flow type, overflow type, spray type and so on. Can be selected according to the actual needs of the project.

　　The study of gas distribution in the packed tower is far less thorough than the study of liquid distribution. Gas flow performance is far greater than the liquid, the gas phase of the lateral mixing rate of at least three times the liquid phase, in the packing layer of the gas Hugh flow path of the zigzagging and its shape of the variability to the study has increased the difficulty. The distribution device of the gas into the tower is not important for small tower wells, where the gas is easily and uniformly distributed. With the development of large void ratio, low pressure drop packing, as well as large diameter, shallow bed packing tower popularization and application, gas distribution has been increasingly important. Uneven gas distribution will cause gas-liquid phase shunting in the packing layer, so that the separation efficiency is seriously reduced. Diameter greater than 3m tower, to consider the gas distribution device, the gas in the tower once the uniform distribution, has been able to maintain a uniform distribution, without having to set the gas redistributor.

　　In addition to gas and liquid distribution device, the design of other tower parts can not be ignored. Such as packing fastening device design and installation is not appropriate, will make the bed changes and even make the loss of filler; filler support device is unreasonable, will reduce the tower's production capacity; liquid collection and redistribution and feeding device has a problem, not only directly affects the gas-liquid distribution, but also affects the concentration distribution. In short, all the tower parts are to make the gas-liquid better contact, in order to play the big efficiency and production capacity of the packed tower.