The porosity is relatively high
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The typical range for the opening ratio of pressure equipment as stated in principles of chemical engineering is <10%, but the actual calculated design opening ratio is around 20%. How can this be adjusted? Is it not possible to reduce the opening ratio any further? What are the disadvantages of too high an open area ratio?
Which tower are you referring to? The opening ratio of a standard plate tower is 10-15%, and the opening area can be determined based on the kinetic energy factor. The size of the plate holes and the spacing between them can be adjusted according to the opening area. If the opening area is too large, the kinetic energy factor is low, resulting in poor gas-liquid contact and even leakage, which directly leads to a decrease in the efficiency of the tower.
An excessively high opening ratio in a plate tower can lead to poor gas-liquid contact, thereby significantly reducing the separation efficiency.
This post was last edited by ownyouinmylife on 2010-8-9 at 13:26. How is that possible? The porosity is determined by referring to a table based on the ratio of the distance between hole centers to the hole diameter; it is not calculated. The opening ratio is determined with the aim of ensuring even fluid distribution; naturally, if it is too high, the performance will be poorer
Increase the tower diameter or reduce the downcomer area
An open area ratio of 20% is nothing to worry about; sometimes it’s even higher than that.
Reply to 6# LTY: My god, I have no idea where you got your standards from – maybe from Mars?
Reply 6# LTY: 20% is already the upper limit for the opening size!
The porosity is the area of the openings divided by the cross-sectional area of the tower (the area of the bubbling zone); since the denominators vary, the standards used to determine it also differ.
Based on active area or based on tower cross-sectional area
This post was last edited by wiseboy on 2011-12-15 20:24. The opening ratio is calculated based on the hydrodynamic requirements of the entire tower; values between 6% and 25% are possible. When the gas-liquid ratio is high, 30% is not uncommon at all! Why is 20% considered too high? The correct order of calculation is: ......> pore velocity ---> total pore area ---> pore diameter/total number of pores ---> pore spacing; in this way, the porosity is determined. Just do the calculations, and the porosity will be whatever it comes out to be. There is no need to set a specific porosity value – don’t reverse the order of operations. Among them: the total pore area is calculated using fluid dynamics. ......>refers to a series of calculations: generalized points, tower diameter, etc. If a porosity value is given, it is an arbitrary and incorrect approach, just as specifying the heat transfer coefficient K arbitrarily in heat exchanger calculations.