Measured product production in VM head

[DestructoMutt]

Reflux Ratio: Column Diameter vs. Product Take-Off Port Diameter
---the theory: initial take-off port size controls the reflux ratio, not what the vapor path is reduced to after the initial take-off port size.

Wash: 3 - 1.5L bottles of 95%ABV, with enough water added to make 10 gallons.
Equilibrium Period: 2 Hours
Input Heat: 1125 Watts (4500W at 240VAC element used at 120VAC)
Column Diameter: 2 inch nominal
Column Height: 46 inches, packed height
Column Packing: 15 copper scrubbers, choreboy brand

Product volume was measured for the first hour of production after the equilibrium period. The take-off valve was fully opened and product was collected for 60 minutes, then cooled to 68F and then the volume was measured. ABV of the product was not measured.


Product condensor and valve match the take-off port size.
Take-Off Port Diameter:......... 2"....................... 1"....................... ½"
RR (theoretical*):................. 1:1..................... 4:1..................... 16:1
Product output:................... 2894ml................1139ml.................. 335ml
RR, observed**.................... 0.93:1................3.26:1....................15.89:1


Valve matches the take-off port size, product condensor is ½" diameter, reduction occurs after 90deg. elbow.
Take-Off Port Diameter:......... 2"....................... 1"....................... ½"
RR (theoretical*):................. 1:1..................... 4:1..................... 16:1
Product output:.................... 345ml.................. 334ml.................. 340ml
RR, observed**.................... 15.37:1................ 15.98:1................ 15.65:1


Valve matches condensor size (½" diamter), reduction occurs immediately after take-off port.
Take-Off Port Diameter:......... 2"......................1"........................ ½"
RR (theoretical*):................. 1:1..................... 4:1..................... 16:1
Product output:....................344ml.................. 337ml.................. 336ml
RR, observed**.....................15.97:1................ 15.77:1................ 15.84:1

Conclusion: it appears that the size of the pathway that the vapor "sees" on it's way to the product condensor is what controls the reflux ratio.

Additional information: The column was allowed to drain overnight, with the reflux and product condensors running. The column packing was not changed throughout the test period. After measuring the volume, all product was returned to the boiler, and the volume was checked for losses. Total losses for the entire test period were less than 225ml. A recirculating cooling system was used; 55 gallon barrel and a pond pump, 150 gal/hr. Cooling water was allowed to return to 72F between tests. Reflux condensor is 1/4"ID copper tube wrapped around a 1" mandrel and 10" overall in length. The bottom of the reflux was held at 2" above the top of the take-off port. The packing stopped 1" below the bottom of the take-off port. The product condensors all used 3/8" ID inlets and outlets for the cooling water, and were 18" long. They were followed up with a coiled liebig of ½" ID copper pipe inside 3/4" copper pipe at 9 feet long. There were no other controls on the cooling water flow. Product take-off valves were positioned as close to the column as possible and in a horizontal orientation. The 2" diameter product condensor was of the graham design (3/8" ID copper coil inside a 2" pipe).

* = Theoretical reflux ratio is based on cross sectional area of column and of the take-off port (nominal dimensions).

** = Observed reflux ratio is calculated from theoretical total of vapor production and actual product take-off.

I started on this test in September of '08, initial planning, the first shakedown run was in October '08. initially i was going to use a sugar wash and monitor the %ABV of the product for the run. but the shakedown run showed some problems. bleeding off the foreshots - for example - i wanted a consistent run each time for each head variation, so i switched to store bought everclear and enough to hopefully eliminate any drop in production due to diminishing alcohol supplies in the wash. the next run, using everclear, was much easier, and i was able to work on a procedure to enable consistent and repeatable runs for each VM variation head. i was then able to do one run every four weeks.....i do have other hobbies and a family...