Methanol Section Daily Question, April 10: What is the purpose of feeding nitrogen into the pipeline that carries the vapor from the top of the atmospheric pressure column in triple-column distillation to the reflux tank?
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What is the purpose of feeding nitrogen into the pipeline from the top gas of the atmospheric pressure column in triple-column distillation to the condenser? This post was last edited by lanseqinghai on 2009-4-10 19:32]
Adjust the pressure at the top of the atmospheric tower; when there is an imbalance in the system’s heat load and negative pressure occurs in the tower, nitrogen can be added to maintain a positive pressure at the tower’s top.
It’s to prevent negative pressure from forming at the top of the atmospheric pressure tower. Our nitrogen supply valve is always kept open; what are the consequences of negative pressure? It would damage the equipment, right? But it shouldn’t have any impact on production, does it?
Short-term negative pressure operation will not have much impact on the equipment; however, if nitrogen is continuously supplied during normal production, it has a significant effect on the distillation process, so this pipeline setup is unnecessary. Typically, distillation towers have nitrogen pipelines in the middle and lower sections.
No, we keep the nitrogen makeup control valve open during normal production!
It has two functions: 1. It allows for replacement during maintenance; 2. It prevents negative pressure from affecting production and damaging the equipment. Logically, this valve should not be in an open position all the time – one should consider whether there is a problem with thermal balance, or whether the heat exchange area of the water cooler is too large.
We don’t have this pipeline; sometimes, when the atmospheric pressure tower is under negative pressure, we activate the nitrogen filling pipeline at the bottom of the tower!
Is there definitely an imbalance in heat? Could you explain it in more detail? I’m not quite sure about this. Thank you!
I think the nitrogen pipeline at the top of the atmospheric pressure tower is used for purging purposes. Generally, there is a nitrogen pipeline at the bottom of the atmospheric pressure tower as well; this is done to prevent negative pressure in the tower. This is achieved by reducing the amount of water flowing into the water cooler at the top of the tower, thereby avoiding excessive condensation. The heat absorbed by the top water cooler is greater than the heat provided by the bottom of the tower, resulting in a negative pressure; hence, there is a heat imbalance.
Our plant’s atmospheric tower top does not have a nitrogen pipeline.
1. Fear of negative pressure; 2. Can be used during replacement
The main purpose is to ensure the safety of the atmospheric pressure tower; when negative pressure develops in this tower, nitrogen can be added to restore positive pressure and maintain a slightly positive pressure condition within it.
If it is used to maintain the system’s pressure, there should also be a vent valve or other mechanisms for automatic pressure control; otherwise, stable operation is required to obtain a qualified product, in order to prevent air from entering when negative pressure occurs. Last edited by Chase on 2009-4-10 21:48.]
How is the blowing function on the 10th floor connected to that location? I don’t understand. This post was last edited by Chase on 2009-4-10 21:53.]
It is mainly to prevent a negative pressure from forming at the top of the atmospheric pressure tower during the production process; therefore, nitrogen is introduced here to ensure operation under a slight positive pressure at the tower top. However, the effectiveness of this approach still needs to be proven through practice! Because the amount of nitrogen added and whether it remains stable are crucial for the operation of the atmospheric pressure tower!
Our company’s atmospheric tower does not have this pipeline; instead, there is a nitrogen pipeline in the tower’s reflux tank, equipped with a check valve. Its main function is to prevent negative pressure in the atmospheric tower. Additionally, to avoid an excess of nitrogen in the reflux tank from affecting product quality, there is also a venting pipeline in place. To ensure stable pressure in the return tank without an excessive accumulation of nitrogen.
Supply nitrogen to maintain a positive pressure at the top of the tower
I also think the main function is to supply nitrogen under negative pressure
Adjust the pressure at the top of the atmospheric pressure tower; when there is an imbalance in the system’s heat load and negative pressure occurs in the tower, nitrogen can be added to maintain a positive pressure at the tower’s top