Liquid holdup in packed spray towers
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In the fine chemical industry, spray towers equipped with polypropylene shell multi-sphere packing are commonly used; how can the liquid holding capacity of the packing layer be estimated? There are several papers on CNKI that seem too complex; is there a simple and reliable way to estimate this? The main factor to consider is the size of the circulation tank – if it’s too small, the liquid may run out before it has a chance to return, preventing the pump from completing the circulation process
The circulation flow rate is determined based on the gas-liquid ratio in the spray tower, and the liquid holdup is determined based on the circulation flow rate. If the circulation flow rate is 25 m3/h, we generally estimate the liquid retention volume for 5 minutes to be about 2 m3. Additionally, the liquid holding capacity is related to the amount of absorbent fluid that needs to be replaced (or the replacement frequency), depending on one’s own needs.
Is 5 minutes too conservative? The 5-meter-tall small tower installed nearby will have the fluid flow back within less than 1 minute
It also depends on the replacement frequency. One minute’s worth of liquid volume is sufficient for you, but if it becomes saturated after just two hours of use, requiring a replacement, isn’t that too much of a hassle? If it is self-controlled, the liquid holding volume can be reduced as much as possible, but it still needs to be at least 2 minutes.
In fact, what needs to be considered primarily is the total amount of liquid in the system during shutdown, in order to determine whether the capacity of the tanks is sufficient. If there is a concern that the liquid level might drop too low, it is possible to start the process by circulating the liquid while simultaneously adding feed, and to stop adding feed once the liquid level in the system becomes stable.
In fact, what needs to be considered primarily is the total amount of liquid in the system during shutdown, in order to determine whether the capacity of the tanks is sufficient. If there is a concern that the liquid level might drop too low, it is possible to start the process by circulating the liquid while simultaneously adding feed, and to stop adding feed once the liquid level in the system becomes stable.