Discussion on the large pressure difference between the upper and lower sections of a floating valve tower
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Dear fellow ship operators, I have just started working with float valve towers. Our company has recently put this type of tower into operation; the ammonia absorption tower in question uses float valves as its main components, with a small amount of benzene-based organic compounds, non-condensable gases, and a large proportion of ammonia present. During operation, it has been observed that once or twice per shift, the system experiences pressure buildup, to the point where even the drainage line (DN40) leading from the top of the tower to the water seal tank is not fast enough to relieve the pressure. The phenomenon is that the pressure at the top of the tower is around 5 Kpa, while the pressure at the lower part of the tower is as high as 26 Kpa (the normal operating value is no more than 10 Kpa). When the drain valves are opened to relieve pressure, it can be observed that organic substances drip down along the pipe walls, but not in a continuous flow. I would like to ask everyone here how floating valve towers can avoid excessive pressure differences between the upper and lower sections, and I also ask everyone to analyze and discuss the possible reasons. The number of trays is roughly twelve. Will an excess of organic matter in the tower affect the operation of the floating valve?
The problem is probably--- 1. Overload operation 2. The downcomer is not unobstructed; for example, there are foreign objects blocking it at the liquid seal (locally), and the level of the liquid seal is unstable
Simply lowering the liquid level seal improved the situation a bit; there is still some organic matter present. The height of the liquid level seal is specified by the technical team, but it seems that so-called technology and parameters are not as reliable as practical experience. The problem is probably--- 1. Overloading operation-------------------------------------------The current load is very low; it has not yet reached the actual production capacity. 2. The downcomer is not unobstructed; if there are foreign objects blocking it at the liquid seal (locally)-------It has been checked, and it is unobstructed. 3. The level of the water seal is unstable--------------------------------------The water circulation was very unstable before, but it is now stable after operation began
Is the reboiler circulation in the floating valve column operating properly? !
The original poster should explain the general situation – are you doing absorption and analysis, or just absorption? It seems to be absorption and analysis based on what you’ve described; it’s possible that the amount of absorption oil used is too large, which makes it difficult for the gas below to rise!
First, check whether the pressure gauge is accurate; if everything is operated properly, then it’s the pressure gauge that isn’t accurate. Second, if the operation has been disrupted, it indicates that flooding has occurred, which may be due to the processing volume exceeding the design limits of the original floating valve tray. Third, there’s also the possibility of blockages – blockages can also lead to flooding, and it’s possible that the guiding floats aren’t installed properly or have become stuck
The key question is: how many years has this tower been in operation, and when did this problem start?
Wow, a post from two years ago has been brought up again! The gas-liquid load inside the ammonia absorption tower can vary significantly; therefore, the kinetic energy factor of the valve orifices should not be too high!
Is the problem solved now? What’s going on?
A large pressure difference indicates that the tray is blocked, or there is poor flow of steam at the top of the tower, or the cooling capacity for the steam at the top is insufficient.