Uniform flow distribution design for gas absorption towers
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This post was last edited by kangqiaowuyun1 on 2022-9-12 at 11:09. I have a question for the experienced colleagues here: there is an adsorption tower filled with activated alumina, used to remove moisture from the gas being recycled. The diameter of the packing material is 3–5 mm, the height of the tower is 1.5 meters (excluding the end caps), and its diameter is 1 meter. The inlet and outlet flanges have a DN65 diameter, and DN50 wire mesh filters are installed inside these flanges to prevent the packing material from entering the pipes. During use, it was found that the adsorption effect was not good; the designed adsorption capacity of 80 hours is currently only 40 hours, and the dew point cannot be maintained. Through operational analysis and regeneration observations, it was found that this short and stubby tower suffers from uneven gas distribution during operation; in other words, the gas does not pass evenly through all the packing elements, taking shortcuts within the tower, which results in the packing not functioning properly. So I would like to ask how I can improve the gas distribution without changing the existing tower. I think I could start by using the DN65 inlet – are there any good distributors available? Another question is whether it is possible to use some packing materials that can help with flow distribution, so that the fine air inlets can be evenly distributed through these packing materials and thus also spread evenly over the activated alumina
For the same volume, aim for a higher height and a smaller tower diameter. Under the current conditions, the only option is to add orifice plates, with an orifice diameter of 4 mm
Is it a pressure vessel that is already in use, with inlet and outlet sizes of only DN65? Can’t add more orifice plates inside anymore, right? Would it work to add ceramic balls or large particles of activated alumina at the bottom?
Is it a pressure vessel that is already in use, with inlet and outlet sizes of only DN65? Can’t add more orifice plates inside anymore, right? Would it work to add ceramic balls or large particles of activated alumina at the bottom?
It seems to be a design issue; everything is designed based on theoretical calculations (under ideal conditions), without any engineering experience. (1) It is recommended to add 1 set, either in series or in parallel, depending on the operating mode. (2) Gas distribution should not be a problem; if there is an issue, considering adding a gas distributor would be a solution, as long as the distributor has an appropriate pressure drop. (3) The tower height is 1.5 m and the tower diameter is 1.0 m; such a design with a thin bed layer inherently poses a risk of gas penetration. It is not known what the gas velocity in an empty tower is, and this gas velocity is also an important factor affecting gas penetration through the bed layer. If this is the reason, it is recommended to use two reactors in series; gas can be withheld from the second reactor initially and added in appropriate amounts as needed.
Parallel connection can also reduce the gas velocity, but it is difficult to control
Add a layer of ceramic balls 200 mm thick
Divert the gas flow and add baffle plates
Large granular balls are placed in the bottom end cap; after leveling them, a layer of wire mesh is added, and then an adsorbent is placed on top. A wire mesh is also installed at the top of the cylinder section, followed by the placement of large granular balls, which helps to ensure even distribution