Are there any hazards associated with methanol distillation flooding?

Because the circulation in the reboiler at the bottom of the tower is caused by the density difference between the cold and hot fluids, flooding the tower affects this circulation first. Secondly, submerging the tower increases the resistance of the liquid; if the evaporation rate is high, entrainment may also occur. Most importantly, if the liquid level rises to the tray level, the separation efficiency will decline significantly.

It’s a topic worth discussing; I hope everyone will speak up actively

Tower flooding: During the distillation process, liquid gradually accumulates above a certain tray, eventually filling part of the tower section and obstructing the upward flow of gas. This prevents proper mass and heat transfer between the gas and liquid phases, a condition known as tower flooding. Phenomenon: When the tower is flooded, the temperature at the top of the tower decreases, the liquid level in the reflux tank drops, while the liquid level and pressure at the bottom of the tower increase. Reason: 1) The sedimentation tube is blocked. The reflux liquid cannot flow downward. At the start of operation, debris such as iron shavings and welding slag, the accumulation of corrosion products on the equipment during normal production, or the precipitation of solids from liquids, along with the self-polymers in solutions, can all easily cause blockages in the downcomers. 2) The amount of liquid is too large, causing the downcomer to become overloaded. Methods: 1) Appropriately reduce the feed rate and return flow rate. 2) If the equipment fails, operations shall be halted for repair.

Methanol is highly volatile and toxic as well

Due to improper operation, such as an excessive amount of steam supplied to the reboiler, the gas flow velocity inside the tower exceeds the limit; the rising gas phase prevents the liquid phase from descending. The pressure built up on the tray causes the tray valve to fail, and the space is first filled with liquid and eventually completely occupied by it. When a large amount of liquid is carried away by the gas outlet, this phenomenon is known as flooding. In distillation, the tower becoming filled with liquid due to an excessive feed rate, insufficient reboiler steam, or high reflux flow for an extended period is known as tower flooding. The hazard is that it prevents the proper operation of this distillation system.

The questions on the 4th and 6th floors have been basically fully answered. After a tower flooding occurs, the tower turns into a container, resulting in an empty level in the reflux tank at the top of the tower, and separation is no longer possible. The main reason is the disruption of material balance; usually, when the distillate quality is unsatisfactory, operators reduce the output flow, but fail to decrease the feed rate in a timely manner. In the event of a tower flooding, feeding must be reduced or stopped; the material inside the tower should be removed until the normal liquid level is reached, after which adjustments can be made, which is equivalent to restarting the distillation process.

Correction: The hazard is the inability to maintain the normal operation of the distillation system.

What was said on the 4th floor seems pretty reasonable