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edited November 2013 in Usage

On a couple of my test runs with water, I've had some flooding (one time it filled the window about half way) on one of my plates. While using 3 plates, it was the middle plate and now with four plates it was the 3rd plate (2nd under the dephlegmator). This seems to occur while knocking down all the vapor with the dephlegmator and as soon as I let up to let some steam through, the flooding goes away.

Any ideas as to what's going on? The problem seemed to go away after the first couple test runs, but with four plates, it occurred again. You might say I'm using too much power, but its about 9kw on an 8" column. It doesn't seem like it should be too much (only running 2 of 5 elements) but perhaps not. Thoughts?



  • I am sure I have read something similar before but can not remember where. Something to do with letting all the plates warm up, cutting power to drain them and then starting again. But that was about perforated plates.

    What does it do with alcohol in the system as water only approximates the conditions at the end of a run. I know some folks us the condition of the lowest plate as a tails indicator.

  • I haven't run with alcohol yet as I've been gaining familiarity with the system before running anything real. I will find out in a few hours what it does with alcohol, but I thought I'd ask the question using water first so I might have some idea on how to mitigate the potential problem if it happens again.

  • So other than the DIY SSR going POP! in the middle of the run when I decided to reduce the amps a little, the run went fine. The top plate under the dephlegmator was loaded the most, but not really flooded. Now to find a reliable power controller...

  • Were you using a fan to help cool it @jbierling? My little DIY only ever sees a 2000 watt element and a fan is not needed but you mentioned an 8" column so I'm assuming 5500 watt element?

  • edited November 2013

    It was the stock build following the DIY instructions so no fan. 4500 watts (20A circuit). Seemed to be fine at full power but it blew a few minutes after turning it down 20% or so. I'd be willing to try rebuilding with a fan if a replacement showed up.

  • 4500 watts with no fan is too much to ask of a $31 DIY controller.

    If you don't understand that I'm very sorry and will give your money back.

    Your comments are asinine because you thought a $31 DIY controller without a cooling fan for 4500 watts (probably 5500 watts) was correct but it certainly is not.

    Fine, dude, get a real controller for hundreds $$ more. While most of us enjoy the SD controller that you simply cannot seem to operate.

  • @jbierling said: It was the stock build following the DIY instructions so no fan. 4500 watts (20A circuit). Seemed to be fine at full power but it blew a few minutes after turning it down 20% or so. I'd be willing to try rebuilding with a fan if a replacement showed up.

    The DIY Controller is a simple and cheap device, but it works. The present DIY Instructions are more a guideline on how to wire the parts, it does not take into account what load you are actually using with it. It has been discussed before, and frankly it should be clear that a heatsink alone is not enough in most cases. It is in the user's discretion to have an electrician have a look at the whole installation before use, to be on the safe side.

    Nevertheless the DIY Controller Kit Instructions need a rewrite, unfortunately nobody has volunteered so far.

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  • The system will always behave differently when running alcohol compared to water.

    During your alcohol run, it is preferable to try and get the plates to behave as similar as possible, though the top plate will always appear to hold more liquid especially when running aggressively.

    A truly flooded top plate suggests too much power.

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  • No. He is running water only til now.
    When he makes a real run, with alcohol, he will understand.

  • edited November 2013

    I don't know which model controller is included in the DIY kit but if you look at any of the similar available devices you will see the importance of cooling.

    Purely as an illustration look at the United Automation PSR 25, as it is a fairly standard alternative.


    The maximum allowable current is SIGNIFICANTLY affected by the thermal ability of the heatsink. With any device a fan is essential in my opinion at higher power usage.

    PSR Heatsink.jpg
    796 x 411 - 49K
  • First, my name is not "Dude"; you can ask Larry what it is if you wish to know. Second, I was not being asinine or complaining, merely reporting what had happened as an aside while trying to understand the topic at hand -- flooding. Third, this was an alcohol (cleaning) run. Fourth for clarity, this 8" column was bought from Still Dragon. Fifth, the DIY controller was only intended to last long enough until the "real" controller arrives. Sixth, the element is 4500w not 5500w.

    Damn, didn't manage to count to 10 before replying.

    @Smaug, what was odd was that the flooding with water was not the top plate but the one under the top plate. With this first alcohol run, the top plate was indeed loaded the most but not what I'd call flooded. I had the thought it could benefit from another downcomer (from 4 to 5)? It would seem to make sense to me that the closer a plate is to the dephlegmator, the more downcomers it needs. Would under 9kw be considered aggressive for the 8"?

    @Moonshine, perhaps including a fan with the DIY controller would be a good idea?

  • Now that is interesting. Why would you think that you need to change the downcommers cross sectional surface area as you move down the column? I don't think I have read that suggestion before. It would not matter if you have too much downcommer capacity, too little is a problem for sure.

    Do you think the recommended qty is wrong? Part of the downcommer function is to collapse foaming and I was under the impression that this was a bigger problem lower down the column.

    Not being difficult here - am honestly interested as I am aware that plate flooding is not always consistent regarding which plate it occurs on. I always thought this was due to the wash being run and not the design of the plates.

  • I run 10 plates with 2 DIY kits for 2 5500w elements, over 15 runs, 12 with 6 plates and 3 with 10 plates so far without any problems with the DIY kits or the plates or the downcomers cross sectional surface area. I never run any element at full power but rather 2 at 75% for warm up then 1 at whatever needed, somewhere bet 12 and 13 amps for the run. I could have spent over 1,000 for an equivalent 11000w controller elsewhere but mine works like a charm. Thanks SD!!

  • @jbierling, I must apologize for my rude behavior. I've had a really hard last few days trying to get the impossible done.

    I answered your post after reading a bigoted post from another member here and my blood was already boiling at the stupidity.
    I did not calm down before responding to your post and for that I am very sorry.

    A mod removed the offensive post but my stupid remarks to you remain and for that please accept my apology.

  • edited November 2013

    As a rule of thumb I recommend that you never run any controller, no matter where you get it from, at over 75% max current.
    Yes you can do so, however it will reduce the life expectancy of the controller. A better option is to run one element on an ON/OFF switch for warm up, and use the controller during the run on another element.

    It is always better to over spec a power controller - irrespective of what you are using it for. Oven, Kiln, Lighting or even a boiler!!

    One other thing which may not have been mentioned. In general controllers produce power spikes when you make sudden control voltage changes. Best to keep your control changes gradual.

  • @Myles what part of the controller actually gives up the ghost normally as I have been having a bit of trouble with my fore mentioned $1000+model I haven't had time to have a good play with it since I found the problem but if I new what part/parts normally crap out I could easily replace them

  • On most controllers whether from individual components on a board or encapsulated like the commonly available items, one of the common failures is thermal runaway. The components overheat and get to a point where there is a cascading current flow. Often this is in the highest power device (Triac) but it can also occur in the trigger circuit (Diac).

    Anyway in effect what happens is the component goes to full ON, overheats, and the current and heat just snowball until it burns out.

    The components last longer if you run at less than max power. However, Even at low power, without adequate cooling something going wrong is inevitable.

  • edited November 2013

    On my 6" column (non-SD) I get a foaming effect on my first plate while equilibrating or returning a lot of reflux. It looks like its flooding, with the foam going above the SG. However, I still get a good temp differential between plates 1 and 2 (around 5C), so I don't think the foam is pushing all the way up. I use 1" downcomers above the plate narrowing to 3/4" below the plate.

    I use the foam as an indicator that I'm working in the sweet spot. If I take off too fast, the foam dies down to nothing, just a single layer of bubbles over the liquid. If the foam is over the SG, I'm wasting time while I could be taking off faster.

    Having a temp probe on every plate will tell you if the plates really are working properly. I have found it very handy. Also, once the plate is out of alcohol, I no longer get bubbles.

    I cook with gas, about 8kW worth.

  • No worries @Lloyd. I wish I'd gotten to 10. I kinda figured something was up.

    Unrelated to flooding but since this has somewhat turned into a discussion about controlling power, I'm not even sure how much control I need. So far I've only done 40ish gallon runs but I seem to get good output so far on either one or two 4500w elements just on or off. There is one 5500w element running on 110v too, but I don't think it puts out enough heat to even keep up with the heat loss.

  • @Myles said: Why would you think that you need to change the downcommers cross sectional surface area as you move down the column?

    My thought was that if there is a bottle neck on a road, you add more lanes. Since there seems to be an excess of liquid trying to get back down, perhaps give it more paths to allow it to go.

  • No you miss-understood my comment. Do you think there is a bigger volume passing through the downcommers on the lower plates?

    Once the plates have filled, the dephlegmator generates a certain volume of condensate. That volume overflows from 1 plate to another until it reaches the boiler. I can understand increasing the downcommer area on all the plates, but am not sure if it needs to change between the plates.

  • I don't think once it condenses it necessarily goes all the way to the boiler. I'm sure some of it is heated sufficiently by vapor going up that it vaporizes again and goes back up. As I understand it this is how lighter fractions concentrate near the top.

  • True, but some of the liquid held on any plate is displaced downwards. That in turn displaces some of the liquid on the next plate downwards etc etc. There is a cycle going on which ultimately results in a similar volume overflowing into the boiler from the lowest plate, as is produced by the dephlegmator. I was not suggesting that the same liquid goes all the way down the column. It should be thoroughly mixed up on each plate.

    What I was asking about is whether there is a need to have a different downcommer capacity at the top plate in comparison to the bottom plate. Plate flooding can occur on any plate, it does not always occur in the same place in the column.

    In general all the plates have the same downcommer cross sectional area. If you need to increase the capacity of the downcommers you do so for all of the plates, as they should all be dealing with similar volumes at any moment in time.

    If you eventually get to the point where you are producing so much reflux condensate that flooding is likely, one solution is to divert some of the liquid from the top plate directly back to the boiler. This reduces the volume passing through the column.
    However, this is only likely to be needed if you are operating at the highest power threshold for the column. Many folks never run their column that hard.

  • Over many runs I've also noticed the top bubble plate has the strongest stream of reflux coming from the downcomer. Each successive plate under that has less and less as the reflux works its way down the column.
    During a really hard (high power) run the top plate is on the verge of flooding while all the lower plates are acting normally. I'm sure this is normal as the top plate is coping with the "cold" reflux and as that plate's liquid drops to the much warmer plate below some alcohol will flash back into vapor, thus decreasing the visible stream flowing from the second plate's downcomer and adding even more work for the top plate.
    I'm with @jbierling on further experimentation just to see how much harder my 4" column could be run by adding an additional downcomer only to the top plate. I conjecture the unaltered plate below the topmost plate would be 'on the verge of flooding' but until I try it its just a guess.
    The question in my mind is will this scheme cause the second plate to behave like the top plate or add a balance across the two plates.

    I typically try to overpower the column and dial it back to a more moderate power setting, usually about 25 to 30% power reduction. This feels comfortable as I'm not in any hurry but I'm also not a commercial distiller where time is money and an extra few liters per hour of production could make a big difference to the bottom line.

  • edited November 2013

    You are absolutely correct there @Lloyd, there are two reasons for flooding, too much power or inadequate size downcomers. I never had any flooding problems with my Flute MkII which had weir downcomers which could handle anything.

  • edited November 2013

    That makes sense Lloyd, and it reinforces what I was trying to say (not very well) - you don't need bigger downcomers on LOWER plates. @olddog - your weirs were probably at the upper end of the recommended range for area relative to plate area, and I suspect they would all be the same size.

    It is logical that an additional downcomer might be useful on the top plate.
    What would be interesting is to see if a twin downcomer on the top plate would cause flooding lower down. I suspect that there is a step change with the biggest reduction in reflux volume being between the top and second plates. From that point onwards single downcomers might be sufficient. Experimentation will show for sure.

  • This could be interesting.
    By sacrificing space for a single bubble cap (on a 4" column) and allocating that space to an additional downcomer it could possibly allow us to run at increased speed. The top plate seems to be the workhorse of the column because it takes the full brunt of the reflux flowing from the dephlegmator. Letting the second plate share that load makes sense.

    It will be a few days before the next run to try this out but will report the results. I smell a video coming on :)

  • The addition of a dc would be far less drastic on 8" vs. 4".

  • @jbierling said: The addition of a dc would be far less drastic on 8" vs. 4".

    True Jbierling, but the good news is that we can populate the 8" with as many DCs as necessary in order to get the top plate to cope and behave as the lower plates do while under the heavy work load of 100% reflux.

    Lets see how Lloyd's experiment plays out.

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  • BTW, you do have each plate populated with 4 DCs,,,,, correct?

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