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meerkat last won the day on July 7 2017

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  1. 2-Pass Condenser Vent Overflow

    Well spotted - I'm glad you solved the problem. I guess that over the years the number of piping problems that I have found that have been caused by fouling problems like this outweighs those caused by design errors by about 10 to 1.
  2. 2-Pass Condenser Vent Overflow

    Can you post a photo of the condenser, the vent and reflux line. It is hard to diagnose piping problems without seeing the piping layout. What size is the reflux line and what is your steam rate? Did the installation work correctly previously, or is this a new setup? If it worked correctly before, what has changed?
  3. Proofing liqueurs: Table 6 question

    The presence of the sugar does mean that Table 6 cannot be used directly. You have to separate the alcohol from the sugar and then use Table 6 on the sugar-free portion. This is described in a series of videos published by the TTB, which you will find at https://www.ttb.gov/spirits/proofing.shtml Parts 3 and 4 of this series are what you need. We have found that with very high levels of sugar the dilution ratios recommended by the TTB do not give accurate results. I wrote about it on these forums in the thread http://adiforums.com/topic/9237-lab-distillation-of-very-high-solids-liqueurs For strategies to use for diluting alcohol with sugar syrup please have a look at my software called AlcoDens LQ. This page is https://www.katmarsoftware.com/alcodenslq.htm This software will enable you to calculate the blending ratios you need to achieve target levels of alcohol and sugar, but the TTB regulations require that you verify the final proof using the methods in the videos referenced above. This is exactly the same as for spirits without sugar, in that you cannot take the results of your proofing calculations (no matter how you do them) as being correct until you have checked the final blend with an hydrometer. There are many threads in these forums discussing gauging and proofing liqueurs. The search function will find them for you.
  4. Bench still for Proofing

    I believe that working at 30°C is a practical solution to the problem, and would be a good way to do internal (i.e. non excise) measurements that you would use for blending or proofing calculations. But you might run into problems with excise authorities who want to impose the letter of the law. There are two areas where the authorities might object. The first is that you will probably not be able to purchase volumetric flasks that are calibrated at 30°C. If you measure 250 ml at 30°C in a flask calibrated for 20°C the true volume (at 20°C) would be 294.4 ml. But if you start with 294.4 ml and then make up to the same 294.4 ml after distillation does that introduce any error? I don't think so. The second possible objection would be that if you measure the proof (or ABV) with an hydrometer at 30°C you would have to correct back to 20°C (or maybe to 60°F) and that is quite a large correction. It can be done, but whether it would be acceptable to your inspector is something you would have to negotiate with them.
  5. Lab distillation of very high-solids liqueurs

    @PeteB I believe that your friend is analyzing his absinthe correctly in accordance with the TTB guidelines, but the TTB procedure is not valid for absinthe in my opinion. If he follows my revised method outlined above he should get the true values. Let me explain my thinking. As far as I know, absinthe contains little or no added sugar. An hydrometer reading on the original absinthe should therefore suffer very little obscuration and the apparent ABV will be very close to the true ABV. The flavorings are present in trace quantities and won't have a material effect. But absinthe typically contains very high levels of alcohol and the TTB procedure will not transfer all the alcohol from the sample to the distillate when using the recommended quantities. It is therefore reasonable that the distillate ABV will be lower than that of the original sample - some of the alcohol is still in the boiling flask. I ran some calculations assuming that the absinthe contains 55 %abv. If the standard 100 ml sample, 50 ml of rinse water and 96 ml of recovered distillate is used I estimate that only about 85% of the original alcohol will report in the distillate. Changing the procedure to my 100 ml sample, 200 ml added water and 196 ml distillate increases the recovery to +99.9%. But remember that the measured abv of the distillate must be doubled to get the original sample abv. There are two reasons why the high alcohol levels cause problems. Firstly there is simply more alcohol in the sample so it is not as easy to get it out. Secondly, the volatility of alcohol relative to water decreases rapidly as the abv increases. We all know that it is much easier to double the strength from 5 abv to 10 abv than it is to go from 45 abv to 90 abv. When the alcohol is dilute it literally leaps out of the water. At high abv you have to really squeeze it. Part of my reasoning in using the higher quantity of added water is to dilute the alcohol and increase its volatility. If you would like to send me the actual sugar and alcohol levels in the absinthe I will rerun the numbers to see how close the calculations come to the measured values.
  6. Lab distillation of very high-solids liqueurs

    @teh_pitts With a true ABV of around 13 % the lab distillations with 50 ml rinse water indicated 0.9 to 1.2 ABV % low.
  7. We have recently experienced some problems when using the standard TTB procedure for determining ABV by lab distillation of liqueurs containing above 30% solids, especially if we have milk solids present. If we start with 100 ml of sample, add 50 ml of rinsing water and then distill off the recommended 96 ml what is left in the boiling flask is so thick that it is impossible to deal with. The actual ABV of the sample is known because we know how much neutral spirit had been added and we know the total volume (from the total mass and measured density). This corresponded very closely with the ABV calculated by AlcoDens LQ, but the lab distillation always gave low results. I suspect this was due to carry over of solids. Even commercial lab results were quite far from the known ABV. We modified the lab distillation procedure and are now getting much more accurate and consistent results, and I would really appreciate your comments if you have experienced similar problems. In our modified procedure we still start with a 100 ml sample but we add 200 ml of water and then distill off 196 ml (which we make up to 200 ml), leaving approximately 100 ml in the boiling flask. This means that the initial solids are still in 100 ml and remain nicely in solution. My calculations show that for a sample containing 15 ABV this procedure will recover +99.99% of the alcohol. Since the alcohol that was initially in 100 ml is now in 200 ml the measured ABV has to be doubled. We understand that this halves the precision of the measurement but the results are so much closer to the known value and are much more consistent - and the glassware is much easier to clean afterwards! How have you gotten around this problem?
  8. Proofing Issues

    It would seem that your blending targeted at 95 proof was actually spot on (and not 95.6) because if you calculate 190 lb of 95 proof plus 1.65 lb of water you get 94.25 proof. I would guess that everything was correct, but your gauging after the first blend gave a slightly higher reading than it should have. Others have also mentioned that immediately after blending the measured proof can be slightly high and the most plausible theory I have come across for this is that micro bubbles of air are mixed into the spirit during blending lowering the density and making the proof appear high. It could of course also be caused by the exothermic blending raising the temperature and decreasing the density, but I presume that you would have corrected for the temperature. Whatever the cause, leaving the blend to settle for 12 hours or so will give the correct proof. What is strange in this case is that the second blending immediately gave the correct/expected proof. Was there any difference in the way you did the first and second blends? How soon after the first blend was completed did you do the gauging, and how long after the gauging did you add the extra water?
  9. How do you measure the spirits quantity ?

    @Still_Holler I am a bit confused about what exactly you are asking because in an earlier post you asked whether temperature corrections need to be applied if the quantity of spirit is measured by weight, but then in your example the quantity is given in volume. Let's look at both alternatives, as applied to your example. If you measure 1000 gallons at 76°F then you would have to use Table 7 to correct the volume to 60°F. As you showed before, the factor is 0.991 and there would be 991 wine gallons at 60°F. For reporting purposes you need the proof gallons and this is simply 991 x 190 / 100 = 1882.9 proof gallons. If you had weighed the same tank you would have got a weight of 6733 lbs. From Table 4 we get that 190 proof spirit has 0.27964 PG/lb so we can calculate the total proof gallons as 6733 x 0.27964 = 1882.8 PG. So in summary, if you have the weight and the proof you can go directly to the proof gallons using Table 4. If you have the volume and the proof then you also need the temperature at which the volume was measured so that you can obtain the volume at 60°F, and then obtain the proof gallons by correcting this volume by the ratio of the actual proof to 100 proof (190/100 in the example).
  10. Ethanol Water Contraction and Dilution

    Thanks to @John Bassett and @HedgeBird for the kind words. @PeteB - please will you make a screen shot of where the problem occurred. I guess it wasn't on the Hydrometer Correction calculator? If it was on one of the blending calculators then maybe I could lock the choice between Proof, ABV and Mass the way that the Standard Temperature can be locked. This would allow all the choices to be fixed for normal work, but leave the option open for the one weird day when you need to blend some European (or Aussie!) ABV spirit with some American Proof spirit.
  11. Pulsing Still

    @Hudson bay distillers If there is such a thing as a universal optimum temperature for the feed to a continuous column then I would say it is the boiling point corresponding to the composition of the feed. If it is colder than this it causes internal reflux in the bottom part of the column which does not do much towards providing a high strength top product. On the other hand if it is hotter than the boiling point you will find that you need to provide a higher reflux ratio from the condenser which increases the water requirements on the condenser but saves a bit of heat on the boiler. But I have seen feed temperatures from substantially below the boiling point all the way through to feeding the column with 100% vapour. If the feed is not a liquid at its boiling point then a change in diameter of the column at the feed point may be required.
  12. Pulsing Still

    From one physics nerd to another.... I believe you are on the right track with your interpretation that it is the boiling that stops and starts. I have seen a similar phenomenon in continuous columns that have significantly oversized external reboilers. These get into a similar cycle of pulsing and the accepted interpretation was always that boiling was stopping and starting. With the very oversized reboiler, heat can be passed through the tubes into the liquid so fast that a vapor blanket is formed on the inside of the tubes. The heat transfer through vapor is much slower than through liquid and suddenly the heat transfer stops. The bouyancy of the vapor gradually causes the vapor to rise out of the reboiler and colder liquid flows in from the bottom of the column. Heat transfer picks up because of the higher thermal conductivity of the liquid and the cycle repeats.
  13. Violent bubbling in the parrot

    To eliminate the liquid U-seal formed by the tapered section below the condenser and the parrot itself you can either lower the parrot or raise the entire condenser. Once you have the levels changed so that the section of pipe coming out of the condenser stand no longer stays flooded with liquid you can install a vent as suggested by Dehner. It probably sounds like a lot of hassle to do, but if you don't this setup will always be awkward to operate.
  14. Violent bubbling in the parrot

    It appears that the stainless vessel to the right of the parrot in the photo is the condenser. If that is so, then you will have a problem installing a vent. In order for the condensed liquid to develop sufficient head to flow over the top edge of the parrot the level of liquid in the condenser will have to build up to slightly higher than the top edge of the parrot. This will create a liquid seal at the bottom of the condenser and gas will not be able to get to the outlet. If you were only concerned with flushing trapped air at startup then the suggestion by PeteB to open the bypass would be adequate. But there will also be dissolved air and CO2 in the fermented beer and this could continue to come out during operation. There will also be light ends (aldehydes etc) that some operators allow to escape from the vent by setting the cooling water flow to get a fairly high temperature for the condensate. Colder isn't always better. By creating a seal at the bottom of the condenser you will force the pressure in the still and condenser to gradually build up (due to incondensible gases) to the point where the seal is blown and you get the surging you are seeing now. In my experience the outlet from the condenser either flows to a small vented pot and then drains from the bottom of the pot to the parrot, or else the vent is mounted on the body of the condenser itself. This second option is common when the condenser is mounted at floor level. We cannot see the other side of the condenser in the photo - perhaps there is already a vent mounted there?
  15. Violent bubbling in the parrot

    When I have seen this in the past it has always been because the product line from the condenser down to the parrot (or flow meter) has been too small and the liquid flowing down entrains air sucked in via the condenser vent. The solution is just to use a larger diameter drain pipe from the condenser. But it seems this is not the reason in your case. If you genuinely do not have a vent after the condenser there is nowhere for the air that is in the system at startup to escape - except via the parrot. As the water is turned to steam and displaces the air, the air will be forced out via the parrot. Seeing that it stops after 10-20 minutes I suspect this is the cause rather than the small drain pipe I mentioned above.