Stacking Columns for Ethanol Fractionation - Snyder vs Vigreux

  • Thread starter Thread starter MoleMan
  • Start date Start date
  • Tags Tags
    Columns
Click For Summary

Discussion Overview

The discussion centers on the fractional distillation of ethanol using different column types, specifically comparing the Snyder column and the Vigreux column. Participants explore the efficiency and placement of these columns in a stacked configuration, as well as the impact of various operational factors on distillation performance.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant reports that their Snyder column produced fractions between 79° and 83° and is considering stacking a Vigreux column to improve efficiency.
  • Another participant suggests that if the Snyder column was not flooding and all balls were chattering, the placement of the Vigreux may not matter, but recommends placing it on top of the Snyder column.
  • A participant mentions that they are running the Vigreux column separately to determine the temperature of ethanol distillation, expecting it to be slightly higher than with the Snyder column, which they believe is more efficient.
  • One participant argues that while the Vigreux may have more theoretical plates, actual efficiency is determined by technique, noting that various factors like distillation speed and atmospheric pressure can affect results.
  • A user claims that their experience with a 3-stage Snyder column shows it achieves separation in half the time compared to a longer Vigreux column, asserting that the Snyder performs better in terms of separation efficiency.

Areas of Agreement / Disagreement

Participants express differing views on the efficiency of the Snyder versus the Vigreux column, with some asserting the Snyder's superiority while others highlight the theoretical advantages of the Vigreux. The discussion remains unresolved regarding the optimal configuration and performance of the stacked columns.

Contextual Notes

Participants mention various operational factors that could influence distillation outcomes, such as column flooding, insulation, distillation speed, and atmospheric pressure changes, but these factors are not fully explored or quantified.

Who May Find This Useful

This discussion may be of interest to individuals involved in home distillation, chemical engineering, or those exploring the practical applications of different distillation column designs.

MoleMan
Messages
2
Reaction score
0
I am fractionally distilling ethanol out of solution.
I have done this with a Snyder column (3-ball)and most of my fraction came over between 79°+ and 83°.
I am wanting to improve upon this and am thinking about stacking a Vigreux in there.

Should the assembly have the Snyder on the top or the bottom?
 
Chemistry news on Phys.org
Were all three balls chattering throughout the distillation? If not you might have had a column that was flooding. If they were, it probably doesn't matter how you place the vigreux column but I would place it on top of the snyder and be careful of flooding. The longer the column, the more likely you will need to insulate it to be able to maintain a distillation.
 
Thanks for the reply.

To answer your question. Yes the Snyder was insulated with the ol paper towel/Al foil-sandwich wrap. It chattered away for hours.

I am now running the Vigreux column separately to see what temp the ethanol comes over at. I expect it to be slightly higher as I have read that a Snyder is more efficient than a Vigreux.

If I could stack columns instead of multiple passes it would be nice.

What are your thoughts on efficiency, 200mm Vigreux vs. 3-ball Snyder.
 
I think the Vigreux would have more theoretical plates but technique will determine the actual efficiency. Don't distill too fast. Temperatures can fluctuate if the pot is overfull, there is bumping and if the pressure in the lab changes. Opening the lab door or sliding up the hood's screen can have some big effects on atmospheric pressure in the lab and the hood.
 
I use a 3-stage Snyder column regularly, and the time it takes to the separation is literally half that required for a Vigreaux colummn of twice the length...and, the Snyder column does a far better job of separation! It would seem that a 3-stage Snyder beats a two-foot Viugreaux.

DrB
 

Similar threads

Replies
1
Views
14K
  • · Replies 2 ·
Replies
2
Views
21K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 8 ·
Replies
8
Views
7K
Replies
3
Views
7K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 27 ·
Replies
27
Views
5K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 8 ·
Replies
8
Views
4K
  • · Replies 7 ·
Replies
7
Views
6K