Regarding the liquid level issue in the mixed refrigerant balance tank
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The mixed refrigerant used in our plant is a five-component mixture. The balance tank for this mixed refrigerant generally does not require drainage; the level gauge is constantly malfunctioning, so it is not possible to see the liquid level using the on-site gauge. However, a large amount of refrigerant can be discharged from the drainage outlet, and it is in liquid form. During this discharge process, severe frosting occurs in the drainage pipes, yet this does not affect the pressure of the gas phase. Is this phenomenon normal? What should the liquid level in the balance tank be? Also, what is the normal level of liquid in the secondary gas-liquid separator?
Do you mean the balance tank at the compressor inlet? The drain in the balance tank allows liquid refrigerant to be removed. On one hand, there is a small amount of liquid present during cooling, and on the other hand, when there is an excess of heavy components, the temperature of the refrigerant at the outlet of the cold box becomes too low, preventing the liquid refrigerant from vaporizing completely.
I don’t feel quite right. Although the presence of a balance tank enables gas-liquid separation, its primary purpose is to ensure that the compressor inlet is free of liquid droplets and to promote uniform mixing of the refrigerant. It is more about ensuring separation; therefore, under controllable conditions, don’t expect the equilibrium tank to separate the two phases. Under normal design conditions, the refrigerant should vaporize completely at the evaporation pressure; obviously, in your plant it has not vaporized completely, as liquid droplets are present in it. The phenomenon is a low inlet temperature of the circulating coolant. There could be two possibilities. The first is that there is a high amount of Reorganized components, especially isopentane – this can be observed directly using real-time online analyzers (but it’s necessary to ensure that the analysis results are accurate; recalibration may be required if needed). Another way is to check the liquid level in the primary separation tank to determine whether there is an excess of isopentane. Second, has this phenomenon always existed, whether in winter or summer? If this phenomenon occurs throughout the year, it is necessary to consider other temperature measurement points in the cold box as well in order to determine whether the insufficient heat exchange area of the pre-cooling plate in the cold box is the cause of the large temperature difference in heat transfer. Also, it’s best to pay attention to this – it’s not a normal phenomenon.
I agree with the views expressed upstairs; I think the same way!