Distillation temp probe

[scorer]

Dear All

We have a small packed column with id 750mm. Can someone please recommend how far into the column the temperature transmitter pockets should extend into the packed sections.
I would think the further they go in, the more the disruption to the liquid flow down the column (more channelling?). However, if too short, will the temp measured be unreliable?

Is it better not to have a pocket?

 

[hacksaw]

the insertion length is secondary since most "pockets" are less than 20 mm od, however you have to decide whether you want the vapor phase, liquid or saturated liquid temperatures.

 

[controlnovice]

Ideally, the best location for the temperature element would be right in the middle of the column, so 375mm.

Too close to the edge and you'll get the temperature of the liquid coming down the walls.

Of course, we only use loosely pack columns so it's easy to place them where we like.

 

[siretb]

Right in the middle is the best location, but anything 100mm away from the wall would do. (I assume that column is insulated). If you use structured packing, a probe (Pt-100 or the like) will easily fit between two beds (without a "pocket").