Ammonia synthesis ammonia cold liquid level
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For ammonia synthesis using horizontal tube-type ammonia cooling, with a flash tank above it, what level do you think is appropriate to maintain for the liquid level? Why?
The liquid level control target in our plant is 20-30%, but in my opinion, it’s sufficient to be able to see the liquid level in the flash tank; if it’s too high, that’s not good either, as space is needed for the liquid ammonia to evaporate into gaseous ammonia. On the other hand, it’s also not acceptable not to be able to see the liquid level, as it’s impossible to know whether the ammonia cooler is filled with liquid ammonia or not. In actual practice, it’s only around 10% at the moment. I’m not sure if my idea is correct; I hope experts can give me some advice! ! !
A too high liquid level in the flash tank can easily lead to ammonia carryover!
Personally, I think it’s hard to say, because the level gauges for ammonia coolers are sometimes installed in the upper part of the equipment, and sometimes throughout the entire device; it depends on where the liquid level actually is within the equipment At the very least, it should allow all of the cracked tubes to be submerged in liquid ammonia
The lower tubes are filled with liquid; what is the liquid level in the flash tank above them, at what position within the flash tank?
The liquid level in the ammonia cooler should not be too high nor too low. Being too high not only causes liquid ammonia to be carried along with the gas, but also results in poor ammonia cooling efficiency due to reduced evaporation space ； If it is too low, too little liquid ammonia will evaporate at the liquid level, resulting in poor ammonia cooling efficiency.
I agree with what was said on the second floor: in an ammonia cooler equipped with a flash tank, the liquid level is generally above the flash tank, and the flash tank is about 4 meters higher than the ammonia cooler. Therefore, it’s sufficient to be able to see the liquid level for control purposes. Personal opinions are for reference only.
It is directly related to the required load; the load on the ammonia cooler is directly tied to the evaporation pressure and liquid level. Since the evaporation pressure generally remains constant, it’s not the amount of liquid level that needs to be controlled, but rather the process parameters that determine what level of liquid level should be maintained.
The liquid level in the ammonia evaporator should be above the heat exchange tubes; a level gauge in the flash tank should be available to monitor this level
I agree with the view from the second floor: it is appropriate to keep the liquid level between 20-30%. If the level is too high, it’s easy for liquid to be carried along with the gas. When the liquid level is around 40-50%, there is less space for ammonia to evaporate, and as a result the temperature of the ammonia in the process gas cannot be reduced. At this point, some operators continue to add more ammonia, but the liquid level doesn’t stay low for long, which leads to the presence of liquid in the gas stream. This can be detected by frost forming on the ammonia gas pipelines and by a decrease in the temperature of the ammonia in the chiller.
It’s better to keep it around 20