Dephlegmator With 3 x Inputs And 3 x Outputs - How To Plumb It?

Hi,

I just got a dephlegmator from a supplier that is similar in configuration to the 4" SD Super Dephlegmator, but mine has 3 inputs and 3 outputs. How on earth are you supposed to plumb that? I'm considering just blocking off 2 ins and 2 outs.

Even with the SD super, what's the point of 2 ins and 2 outs?

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Comments

  • Like this? Again, what's the point?

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  • edited June 24

    Yep, plug off the ones you don't need.

    Keep in mind, for PID control, a temperature probe in the dephleg provides more accuracy and better response time.

    Small diameters don't necessary need dual inputs, but when you get larger, double inputs provide for a more even temperature gradient inside the dephleg. For example, we use 2 inputs/outputs on our 12", and use the additional port at the top to measure dephleg temperature for control.

    I could also imagine using both a temp probe for control, and a dial thermometer on it - that way you can have a real time view at temp when operating the still. That takes 2 of the 3 top ports.

  • It also allows you to use Grim's Crazy Alternative Condenser Plumbing Scheme.

    Where there is a pump plumbed onto the condenser, circulating from the bottom to the top, separate from coolant input/output loop.

    You can supercharge condenser performance with this approach, and more effectively use warmer water as your coolant.

  • The multiple inputs can be utilized to help mitigate the channeling effect that can occur at slower flow rates.

    Basically helping to avoid hot spots on one side of the shell.

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  • Perhaps you could ask the manufacturer how to plumb it...... :O)

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  • I did consider trying to find something like a danfoss control to use for one of the ports.

  • @punkin said: Perhaps you could ask the manufacturer how to plumb it...... :O)

    my first thought... but probably for a dial thermometer or temp probe...

  • @CothermanDistilling said: my first thought... but probably for a dial thermometer or temp probe...

    I just got done reading your thread from 6 years ago on danfoss valves. I've just found an FJVA on eBay for a decent price.. I'm presuming that despite them not being as sensitive as the valves with the probe that theynare still good enough

  • @needmorstuff said: I just got done reading your thread from 6 years ago on danfoss valves. I've just found an FJVA on eBay for a decent price.. I'm presuming that despite them not being as sensitive as the valves with the probe that they are still good enough

    I use thermostatic for PC only, not the RC. I use a PID and an electronic probe for the RC.

    If you use a thermostatic without a probe in any kind of condenser, I am not sure how it will work, it could be a complete waste of money, and make sure it has an internal bypass, because if it shuts off completely, how does it get hot to turn back on again? that sounds REALLY DANGEROUS!

  • edited June 26

    Unless one can provide stable, uniform cooling media temps for the duration of the distillation run, it is best to have the temp station in the vapor path above the dephlegmator with a modulating flow control valve tied to the PID.

    Placing valve on the discharge side to avoid any siphoning effect. Also, a default closed position on the valve will help alert you if there is a problem with the valve operation. Default in the open position can make trouble shooting more confusing.

    Modulating valves on the PC should always default to open position.

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  • @CothermanDistilling said: it does have an internal bypass. spec sheet (PDF)

    re using for RC, on adi southernhighlander from olympic recommends going out of PC through temp sensor into RC.. says it works a charm. That is however using the one with external probe. Maybe I should ask over there...

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  • Oops here comes the car salesman :))

  • If I understand your last post correctly, PCs easily affected by flow rates will have a limited operating range when tying the cooling circuits of PC and RC together.

    If the PC is small and easily affected by flow rates, the RC should have it's own dedicated cooling circuit.

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  • @richard said: Oops here comes the car salesman :))

    Pardon?

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  • @Smaug said: Pardon?

    I think Richard might be referring to the gent from the other forum.

    I think I have just had a moment of clarity anyway, just gonna learn my rig manual first lol.. using separate flow inputs and needle valves.

  • edited June 27

    @needmorstuff said: I think I have just had a moment of clarity anyway, just gonna learn my rig manual first lol.. using separate flow inputs and needle valves.

    Ah sure,

    IMO, that's really the best way.
    Then set up your automation accordingly.

    StillDragon North America - Your StillDragon® Distributor for North America

  • @needmorstuff said: re using for RC, on adi southernhighlander from olympic recommends going out of PC through temp sensor into RC.. says it works a charm. That is however using the one with external probe. Maybe I should ask over there...

    If you want one cooling circuit, go for it... you can learn the hard way, and maybe that is best... but none of what I have done with the thermostatic on the PC and the PID on the RC will apply, because you will have two automated systems that will fight each other. Especially when you understand that PC's are most effective with a low flow of cool water, and RC's are best at high flow or warm water. Keep in mind mine is not just 'talk', I am running a production distillery with a 1000L still on a daily basis with no mechanical chiller, only sub-tropical Florida water temps...

  • I said in my last comment I'm going dual flow and manual. Walk before you run, right.

  • @grim said: It also allows you to use Grim's Crazy Alternative Condenser Plumbing Scheme.

    Where there is a pump plumbed onto the condenser, circulating from the bottom to the top, separate from coolant input/output loop.

    You can supercharge condenser performance with this approach, and more effectively use warmer water as your coolant.

    I do not understand. I must be missing something.

  • Increasing the flow rate through the condenser increases efficiency

  • edited July 3

    Always the paradox of what constitutes efficient behavior in distilling.
    More flow= inefficiency

    More surface area = more expensive = inefficiency.
    Or, more surface area= more efficient.

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  • @needmorstuff said: Increasing the flow rate through the condenser increases efficiency

    Not sure about that. It increases your cooling capacity for sure, but might waste energy & water.

    @Smaug said: Always the paradox of what constitutes efficient behavior in distilling.
    More flow= inefficiency

    More surface area = more expensive = inefficiency.

    Not sure that is what @grim is talking about though. I don't think he's talking about efficiency or inefficiency.

    What I think he's suggesting is adding some cooling water to the top of the condenser as a good thing. Why I'm not sure, I'm guessing there might be turbulence created at the top of the condenser which will somehow increase your cooling capacity. Maybe??

    I suppose it is possible, but I don't understand why you'd need a pump either. What you're effectively doing is creating a partial bypass which would just need a pipe between a top and bottom port and a valve to control flow. Surely he's not trying to reverse part of the flow in the condenser? Maybe??

    Need more details please ;)

  • edited July 2

    Sure. But text book would say more flow = inefficiency.

    More of any practical thing almost always = inefficiency.

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  • Sorry. Just being argumentative.

    StillDragon North America - Your StillDragon® Distributor for North America

  • @Smaug said: Sure. But text book would say more flow = inefficiency.

    More of any practical thing almost always = inefficiency.

    I agree with this.

    Now we're just waiting for the man himself to tell us what he's talking about.

    I have to think he actually is proposing partially reversing the flow. How to avoid just sucking all the cool water out of the bottom when you're pumping it to the top would be the key I think.

  • edited July 2

    Circulation loop on the condenser itself increases overall condenser efficiency due to turbulent flow and allows for a higher input t, or lower coolant flow rates.

    Catch 22 in distilling condensers is that you can’t adjust input temperature such that flow rate is high enough to move out of inefficient laminar flow. Most of us have no control of input t.

    So how do you increase flow rate to improve condenser efficiency?

    You increase the flow rate independently of the the coolant flow, by adding a pump to create a high velocity turbulent flow within the shell.

    Makes more of a difference with larger condenser, especially baffle-less designs.

    For reflux condensers - this allows you to hold the entire tube side surface at a set temperature, without risking sub-cooled reflux. The result is being able to increase the vapor knock down ability, as you no longer have any gradient at all.

  • So this after more thinking like I said above is indeed what you were referring to, reversing part of the flow. Seems like an odd way to achieve turbulence, but given that most of us have to make the best out of what we have, it makes sense that it could work.

    Given that most of these condensers have their inputs and outputs physically close to each other, how do you manage to make sure you're just not pumping all of your cold input water straight to the top?

  • edited July 3

    I suppose that could be the case with a small pump, But would be counterproductive to run a small pump if the goal is increased turbulence. I’d say 10x your typical coolant flow rate or condenser volume to keep the coolant in the shell thoroughly mixed and at a consistent temp.

  • The main advantage of counter flow cooling is that your product temperature should be nearly the same as your coolant temperature. If our coolant is already warm the technique you describe would make our product even warmer than it would otherwise be. So the cooling capacity might increase, but with a tradeoff which in most cases wouldn't be a good thing.

    One of these days I'm going to add two stage cooling in the form of a short condenser under my main product condenser. The main one would do the vast majority of the work, and perhaps be set up the way you describe, but the 2nd stage could be on its own loop and would get the product nice and cool since it wouldn't need to drop the temperature very much.

  • Yeah that’s ideal for PC.

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