Glass Marbles for Reflux Column Structured Packing

[rad14701]

I'm starting this topic to open a discussion about using glass marbles for structured packing in reflux columns... I have always considered marbles to be underestimated as far as their effectiveness as structured packing and would like to see whether anyone else has used them, whether successfully or unsuccessfully...

Checking the parent site one might surmise that marbles wouldn't be worthwhile from a purity standpoint... I have always disagreed but never did any testing to prove out my stance... Using the HETP's Calculator with various settings, and comparing between marbles and SS scrubbers, performance would seem dismal at first glance... However, I feel that theoretical and practical results differ greatly for a multitude of reasons... For example, setting the calculator to some baseline numbers of Column Diameter = 0.1, Packing Height = 1m, Reflux Ratio = 1, and Power Input = 1000W, SS scrubbers supposedly yield 0.085m HETP, 13.8 plates, and 95% ABV while marbles yield 0.256m HETP, 5.9 plates, and 91.9% ABV... Based on those numbers one might assume that in practical application marbles would be less than satisfactory for neutral spirits... In reality, this is not the case - at least in my own personal experience...

I recently began glass marbles in my small scale 1.25"/32mm LM reflux column with greater success than I had expected... What surprised me the most was the fact that I attained my highest purity spirits by using them... I was also surprised by how stable the run went and how the ABV hung right at 96.5% all the way to the tails at a seemingly rapid take off rate for such a small diameter column... Had I slowed down my take off rate I may have been able to further compress the tails but I have found that it's easier to just increase the heat input because the take off rate drops as soon as the transition from hearts to tails occurs...

The packed column section measures 30" and is completely filled with marbles with the exception of the top 1" and bottom 2" which have SS scrubber to hold the marbles in place during assembly and dis-assembly... I am using a concentric reflux condenser on top of my dual reducer LM head which has recently been fitted with an external reflux return tube, located on the back side and not visible in the picture below...

My last run of 3 gallons of 40% low wines produced 2.5 liters of ~95%+ neutral spirits, making overly conservative cuts from the 3.75 liters collected in total... While there were more acceptable spirits which could have been blended, I chose not to be greedy and tossed all but foreshots into the feints jug...

Let the discussion begin...

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