3 replies to this topic

[boringppl]

Hi,

I am now doing the design for distillation column and I had found that the top section of the column is larger than the bottom section. Hence, I have no idea on the design about swaged section i.e vertical distance, angle from vertical, is it after or before the feed stages and is there any design limit for it?
Thank you very much. Really appreciate for the helps.
Thank you.

Boringppl

[Technical Bard]

The maximum angle of the swage is dependent on design pressure / temperature, materials, wall thickness, etc. because the of the mechanical stress limits.

A typical rule is to use angles no greater than 30° from vertical, although I have seen greater used with a lot of mechanical engineering assessment. Talk to your mechanical engineer and/or vessel fabricator about these limits.

[boringppl]

Thank you for the reply.

I am actually a final year student who doing a design project. Therefore, there is no mechanical engineer to ask for.. haha... Anyway, thank you very much for your help.


Regards,
Boringppl

[Dipankarc84]

Boringppl

There are two aspects to your design here:
1. Process Aspect
2. Mechanical Aspect

When you are carrying out the conceptual design, you should be satisfying the Process Aspects first before deciding the swage angle. By Process Aspect, I mean looking at the Column Internals arrangement based on the Vapor Liquid Traffic, type of internal and de-entrainment requirements.

To make it simpler, you should first check what kind of internals you have above and below the swaged section, e.g Packing bed limiters, gas injection plates, chimney trays, normal trays or distributors.

Based on the internals, there will be a minimum height requirement for de-entraining the upward moving vapors (~350 to 400 mm of free space). In case of a trough distributor, you might have to check the liquid pool height on the bed which in turn will fix your riser heights. All these parameters need to be checked first. This will give you the "minimum" height required between your variable diameter sections of the column. Once, these are satisfied, you have to look at the Mechanical Aspects like angle of swaging and reinforcement requirements, which have been discussed already.