4 replies to this topic

[polipo]

Hi there,

I would really like to ask you guy, whoever could clarify please, about the phenomenon in the distillation column. I wonder that is it necessary to have flooding and drying in the lower tray present simultaneously. Is it possible to have drying tray, no liquid in that tray all, without flooding on the upper trays. And lastly, if the drying occurred, what would be the effect?

Thx for all your assistances.
This is necessary for me to go through this subject.
Thx sincerely again.

[Root]

Hi there,

I would really like to ask you guy, whoever could clarify please, about the phenomenon in the distillation column. I wonder that is it necessary to have flooding and drying in the lower tray present simultaneously. Is it possible to have drying tray, no liquid in that tray all, without flooding on the upper trays. And lastly, if the drying occurred, what would be the effect?

Thx for all your assistances.
This is necessary for me to go through this subject.
Thx sincerely again.

Hi,

Which tray is dry and which tray is in flooding condition, elaborate your question bit more.
Cheers
Toor

[polipo]

Hi there,

I would really like to ask you guy, whoever could clarify please, about the phenomenon in the distillation column. I wonder that is it necessary to have flooding and drying in the lower tray present simultaneously. Is it possible to have drying tray, no liquid in that tray all, without flooding on the upper trays. And lastly, if the drying occurred, what would be the effect?

Thx for all your assistances.
This is necessary for me to go through this subject.
Thx sincerely again.

Hi,

Which tray is dry and which tray is in flooding condition, elaborate your question bit more.
Cheers
Toor

I mean in general. I would like some explanation.
1. During the operation of the column, flooding may occur. Once the flooding occurs, suppose in 7th tray of the 18-trayed distillation column (counting from bottom to top), is it necessary to have drying, no liquid, on 6th tray.
2. Can the drying of tray occur without prevalent flooding phenomenon?
3. Whenever any trays have been drying, what would be the effect?

I could specify as this, no more. I have no practical example because I felt doubtful when I read the books.

That's very kind of you.
Thank a bunch.

[Zauberberg]

1. Inability of liquid to cascade down the tower due to excessive vapor flow (dry pressure drop) will cause liquid to backup and there will be subsequent dry-out of trays below the initial flood point. In practice, you will recognize this phenomenon by the lost level in tower bottoms. However, flooding does not need to mean that complete loss of liquid traffic has happened - that varies from case to case.

In the event of hydraulic flood (high liquid rates), choking of the downcomer can cause dry-out of trays below as well. I've seen this scenario on several occasions in high pressure fractionators. There was cycling in tower operation, i.e. when liquid level on the tray during flooding exceeds certain value the liquid will simply dump through the tray and cause bottom level to rise suddenly. And then the cycle repeats.

2. Yes it can, particularly at extremely low liquid rates and high vapor rates (e.g. absorber in TEG dehydration unit).

3. Complete loss of separation, product off-spec. What more do we need?

[Root]

Hi there,

I would really like to ask you guy, whoever could clarify please, about the phenomenon in the distillation column. I wonder that is it necessary to have flooding and drying in the lower tray present simultaneously. Is it possible to have drying tray, no liquid in that tray all, without flooding on the upper trays. And lastly, if the drying occurred, what would be the effect?

Thx for all your assistances.
This is necessary for me to go through this subject.
Thx sincerely again.

Hi,

Which tray is dry and which tray is in flooding condition, elaborate your question bit more.
Cheers
Toor

I mean in general. I would like some explanation.
1. During the operation of the column, flooding may occur. Once the flooding occurs, suppose in 7th tray of the 18-trayed distillation column (counting from bottom to top), is it necessary to have drying, no liquid, on 6th tray.
2. Can the drying of tray occur without prevalent flooding phenomenon?
3. Whenever any trays have been drying, what would be the effect?

I could specify as this, no more. I have no practical example because I felt doubtful when I read the books.

That's very kind of you.
Thank a bunch.

Hi,
1- Strat from btm, 1~18, you mentioned tray 7 Flooding and effect on tray 6; Yes Tray could be Dry, high velocity of vapors will be the main cuase and this could be due to high feed temperature or failure of condencer.
2- Yes this could be and denpend on feed composition and feed temperature and reflex.
3- Production will be off spec.
Hope this will help you.
Cheers
Toor.