Where do these non-condensable gases come from?
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Our factory has a distillation tower that is operated intermittently. Each time it is started up, it is necessary to vent the non-condensable gases from the top of the tower. I would like to know: where do these non-condensable gases come from?
Could you give an example to explain in detail?
It is estimated to have been brought in with the feed, and accumulated inside the tower when it was shut down.
One comes from the feed belt, and another leaks in from the atmosphere.
It’s those non-condensable gases present in the feed composition, which become concentrated. In fact, it’s not only necessary to drain it before driving; non-condensable gas also needs to be drained after the system has been running for a long period of time. Otherwise, it will affect the pressure of the distillation tower
When a batch distillation column is shut down, the material is drained and the column system is cooled. If a slight positive pressure is to be maintained in the column, nitrogen must be introduced during the cooling process; otherwise, the column pressure will continue to drop as it cools, potentially resulting in a negative pressure. However, anyone with basic knowledge of chemical engineering will introduce nitrogen during cooling to maintain a slight positive pressure. When driving the machine again, the material at the bottom of the tower vaporizes, and this nitrogen is gradually pushed upward; at this point it is necessary to vent the non-condensable gases, which are mostly nitrogen in such cases.
It could be present in the raw material or brought in from the air during feeding
Regardless of the boiling point of the material, as the temperature drops, the volume should decrease, right? The tower may develop negative pressure, which could draw in impure gases; venting non-condensable gases is done to maintain the purity of the system. Personal understanding