On the selection of packing types for packed towers
Thread Content
This post was last edited by jinjinaaaaaaaa on 2019-4-20 at 21:57. The screenshots above are from the \"Modern Packed Tower Technology Guide\". Based on the information provided, the questions are as follows: 1. According to the FP criterion, if the value is greater than 0.3, bulk stacking should be preferred； Based on the mass transfer mode, gas film control takes precedence ； 2. In LNG receiving stations, the absorption of BOG by LNG should be controlled via a gas film mechanism, and its FP should be close to 1, which is much higher than the aforementioned limit of 0.3; this creates a contradiction. As for what type of packing is better and more suitable for the recondenser in receiving stations, in actual operation the difference may not be that significant. I wonder, in theory, which one is better. I hope everyone will engage in active discussions. Thank you!
This post was last edited by arpcd on 2019-4-24 at 22:56. Well, regarding this BOG recondenser mentioned by the original poster, you shouldn’t consider it an absorption tower; it is definitely a heat exchanger. What matters most here is its heat exchange capacity, or rather, the heat exchange capacity at the inlet of this tower. As for the liquid film or gas film, that’s not important in this case. For BOG, as long as its temperature is lowered, it can be absorbed. Otherwise, such a device should be called a reabsorption tower rather than a recondenser. Therefore, the conclusion is clear: under high pressure and high FP conditions, loose packing is the preferred choice. Looking at the screenshot, the random-packed packing is C, with moderate performance, while the regularly packed packing is D, with poor performance. . This is why, in industry, for most of these direct-contact heat exchangers, that is, absorption towers where heat transfer efficiency is crucial, random-packed packing is generally chosen for operation under pressure.
Thank you, big bro. I did consider this issue from the perspective of pure absorption towers before; heat exchange mainly takes place inside the recondenser, and the FP value is also high. Under these circumstances, packed beds are clearly the more suitable option.