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Temperature Sensor Locations?

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  • It will be interesting to see how it goes with the pond pump since those pumps usually don't have a lot of pressure behind them and are usually defeated at about 8 feet of head.

    800 ltrs/hr = 13 ltrs/min, is this sufficient flow for the dephleg?

  • edited June 2014

    Just for reference, the Danfoss AVTA valve used on most every big German still has a Cv value of 2.2 in the 1/2" version and a 4.0 in the 3/4" version, so I would assume slightly higher flow rates than this specific Johnson valve, but absolutely in the ball park. However, at municipal water pressures the valve is noisy, definitely some cavitation, etc. So slightly larger might be the key.

    I can't imagine either the dephlegmator or product condenser presenting any appreciable pressure drop.

  • Have you got the valve piped in the correct way? There should be A and AB marked on the valve or an arrow for flow. Have you got the valve on the outlet of the dephleg and not the inlet?

  • edited June 2014

    Valve was backwards, B to A, it's a bit quieter now from A to B. The output line is running free, with even just a minimum of restriction on the output line, the valve quiets down almost immediately. I believe this means a higher Cv is needed. Although really, it's very minor. If I cut some of the supply pressure, it quiets down immediately as well.

    3-way might be the better choice in a recirc system. I went with a two-way since the goal was to use the condensers to pre-heat mash water.

    800L/h - 13L liters per minute, 210 gallons per hour - should be sufficient for the big systems, but this is really going to be dependent on the cooling water temp and condenser efficiency.

    We'll see how it does with the little pond pump as soon as I can go out to pick up a fitting.

  • Glad you got it sorted. Sounds like the CV of 1.2 is about spot on, if you go bigger you probably wont be able to control it at low flows with the town pressure. The minimum restriction you put on the line mimics what happens in a closed loop system with a bit of back pressure on the valve.

    The 13ltrs/min is what worries me at higher condenser water temps which may need the higher CV rated valves. Keep us informed of your experiments, input power, inlet/outlet water temps, valve position.

    What size SD are you using, element size?

    Thanks grim.

  • edited June 2014

    Ok, using a RIO Plus 2100 pond pump (35 watts, 2600l/h), same setup as above. Surprisingly this thing did not keel over and die, although it probably will.

    25% - 30L/hr (0.5L/min)

    50% - 120 L/hr (2L/min)

    100% - 280L/hr (4.6L/min)

    I wouldn't recommend this pump, you'd need to go larger. According to the specs, the max head on this is exactly what Micki stated, 8 feet, so no surprises.

  • Just out of interest what is the flow of that pump without the valve fitted, piped directly to the dephleg? Sorry to this to you grim but I am just interested to see these figures, if your flow rates are are accurate to about +/-10% I can work out the pressure drop across the dephleg. Thanks mate.

  • so glad you guys are here having this conversation, I have all the parts, the johnson valves, a lot of solenoid valves, several danfoss valves, but waiting on the last of the concrete to get poured, so just drooling... I also have a wide variety of pumps from my buddy at depco pump.. I have one that is a 60psi internal switch I was thinking about hooking up to one of those blue pressure tanks with bladder... Thanks again!

  • edited June 2014

    Ok, with the pond pump it looks like 290l/hr with the valve out.

  • so I am taking it that pond pump would be good with three way valve if third port goes back to the 'pond'...

  • edited June 2014

    With the dephleg completely out, I'm seeing 290-300l/hr - maybe closer to 300l/hr. My error rate may be high since I am extrapolating the hourly flow. I am taking a measurement of the time it takes to flow 2 liters and calculating from there.

    I think the pump is being choked by the restriction of 12 feet of 3/8ths ID push hose, and the head, of course. The output nozzle of the pump is 1/2".

  • On a side note, I was also thinking about welding a fitting of some (swagelock probably) sort near the top of the dephleg and putting a curved pipe up into it and a air bleeder valve in, there has to be some residual air no matter which way you push water through... maybe a combination air bleed and vacuum break?

  • Submerge the end of your return hose into the coolant tank, such that air bubbles can't work their way back upwards, or you aren't draining into a mostly open pipe. Open your coolant flow wide open when you start, and you'll force most of the residual air out.

  • I think that works with city water pressure, you think most recirc pumps will have the oomph to do it???

  • edited June 2014

    This little pond pump probably only has enough flow for a small dephleg, maybe not even enough for a 4" column, unless the coolant was very cold. Pond pump should probably be thrown back into the pond. I would suggest you compare pump curves and go much larger.

  • edited June 2014

    @CothermanDistilling don't you have a March Chugger? With 19 feet of head and a 22L/min flow rate, it looks like it would be a great pairing. Get down on the floor and plumb it up.

  • A 20l bucket may be a better way to measure than a 2l jar. It will take a lot of the error out using a larger sample. Just use the beaker to make twenty litres and mark that on the 5g bucket.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • I have a couple 809's, 815, 815SS, MD3, MD5, MD5.5SS, etc... but also some other ones, for instance I use a macerator pump off a boat to transfer stuff that may have yeast or solids in it, it is sold as a marine poop pump, has a blender blade in it and self primes..

  • edited June 2014

    @CothermanDistilling said: for instance I use a macerator pump off a boat to transfer stuff that may have yeast or solids in it, it is sold as a marine poop pump, has a blender blade in it and self primes..

    I would use this to pump rum with some pineapple and coconut solids in it.

  • edited June 2014

    Perhaps we need everyone to post their setup size, power requirements, and typical flow rates.

    We could probably work through the appropriate valve and pump sizes for each range. I could see at least 3 different combinations being required.

  • Thanks for doing that @grim. Just as I suspected the pressure drop across the dephleg is about 0.7-1.2kPa. Arse cheeks have more resistance to a fart than that. So going with a higher CV valve probably wont increase flow by much as the flow only increased by about 10-20l/hr without the valve installed. You need to decrease the pipe resistance, go with 1/2" flow and return hoses.

    @CothermanDistilling said: so I am taking it that pond pump would be good with three way valve if third port goes back to the 'pond'...

    This all still depends on the CV of the valve. A 3 way and a 2 way valve with a CV of 1.2 will both have the same flow characteristics, the 3 way valve wont decrease the pressure drop or increase flow, the third port just diverts water away instead of backing it up. Its all a balancing act about pressure versus flow to get it right.

    If you feed the dephleg from the bottom then there should be no airlocks, fed from the top it will be all air. This gets tricky when working with pharmaceuticals especially refluxing acids at high temps, the condensers on these setups are top fed, airlocks here can cause explosions. They use another valve to prime the condenser from the bottom and then change it over to feed from the top.

    All the condensers I have worked with have been fed from the top, according to my chemical engineer mates, reflux should take place in the lower 1/3 of the condenser, this is called the primary condensation point. Any vapour that has not condensed in this lower 1/3 will condense in the next 2/3 as the condenser gets cooler the higher up you go, makes sense.

    If it is fed from the bottom, the higher you go up the condenser the higher the surface temperature of the condenser, makes sense. So anything that should have condensed at the lower temps will not have a chance to condense fully past the primary condensation point as it simply gets hotter above this point. There is a massive formula for working out condenser efficiency and the biggest factors in this are the temperature of the fluid in the condenser, the thermal exchange rate of the condenser material, the surface area the vapour is in contact with and atmospheric pressure. The formula assumes the condenser is fed from the top.

    From other things they told me, a top feed will have a lower water consumption as well since you are allowing the full surface area of the condenser to do the work not just the lower cooler part as it would be in a bottom feed.

  • edited June 2014

    Spoke to another chemical engineer today and he disagrees with the others, reckons alcohol is a lighter vapour than what Derrick is used to working with and alcohol dephlegs should be fed from the bottom, something to do with liquid/vapour interchange. I must read now so I understand what the fuck they are talking about. Anyway if you can get a bunch of experts arguing and disagreeing then there are obviously no set rules here. As I know bugger all about distilling I cant comment any further except to say if you have something that works don't change it. I cant wait to get home and order my still and start experimenting.

  • edited June 2014

    @Mickiboi said: Just as I suspected the pressure drop across the dephleg is about 0.7-1.2kPa.

    I'd wager a bet that this has more to do with the 3/8ths input and output fittings I have on my test rig dephlegmator, versus the restriction provided by the tube-in-shell design. Once you get into the shell, it's wide open. Obviously this would be very different from a coil or tight liebig.

    I wonder if even the smaller rig dephlegmators should be using larger piping and fittings, not because they need more flow, but because they need less head restriction to be able to use smaller pumps. 1/2" all around would be much easier pump load.

    Just a brief literature review of the forumosphere indicates that folks are using massively oversized pumps in their recirculating setups, which is surprising, because most of these monster sump pumps will be generating quite a bit of heat, and that heat is going to be heating up the coolant reservoir.

    Saw one case of someone using a 1/4 horsepower sump pump on a 2" column dephlegmator. I'd say that the temp rise they see in their reservoir has nothing to do with the dephlegmator cooling load, and everything to do with the 500 watt heat sink in the tub.

    Suspect in many of these cases, a much smaller externally mounted pump and larger hose would result in significant energy savings and a much easier time controlling heat load.

  • In my practice if found feeding from the bottom to work much better. More cooling and less water.

    The dephlegmator is so short that I'd think there would be almost no temp gradient.

  • edited June 2014

    @jbierling said: In my practice if found feeding from the bottom to work much better. More cooling and less water.

    The dephlegmator is so short that I'd think there would be almost no temp gradient.

    That's entirely possible, the titanium condensers used in pharmaceutical industry can be up to 2 metres long. They are HUGE. There is a definite temperature decrease along these monsters.

    So you think 1/2" fittings should be on the dephleg?

  • I think I want to make a dephleg out of a Sight Glass tower to see the water.... or have the water on the inside of the copper tubes and the cartridge go into the glass with 2 orings on the top and 2 on the bottom so you can see vapor condense... I hate you guys, my brain cannot stop when you give it these weird ideas...

    Picture this: Multiple copper tubes about the length of the height of the glass in the SGT Stainless plates .010" or so smaller than the ID of the glass, about 10mm thick Stainless plates outer diameter therefore is larger than the ID of the SGT seal and end cap Stainless plates have holes with o-ring grooves in them and have a smaller ID one side to keep copper tubes in place Stainless plates have outer groove with o-ring above and below it, this void also has passages drilled to pass water to tubes SGT end caps have 3/4" TC fittings between the glass mating surface and ferrules one on top and one on bottom

    I know there are technicalities to overcome, but it would be a cool dephleg!

  • edited June 2014

    Everything is a trade off in one way or another. If you are running off municipal water, your water pressure is high enough that the hose and fittings are irrelevant. It's only the recirc scenario where it becomes more important. However, 1/2" also becomes much more complicated as push-fit hoses in 1/2" (pex) are no longer as flexible and will be difficult to work with, you'd probably need to move to rubber hoses or use a more complex plumbing arrangement (push fit 90's, etc).

    Also don't think there will be a one-size-fits-all solution here - realistically, the sizing for a 4" dephleg is going to be completely different than an 8" dephleg, and still different from a 12" dephleg. Realistically, we'll probably need 2 or 3 different valve suggestions and at least 3 different pump suggestions.

    There's got to be a better way than using an overkill pump throttled down to single digits flow rates.

  • edited June 2014

    Interesting idea @CothermanDistilling. Does your brain ever stop? I love the idea of seeing the vapour condense.

    @grim I was thinking about a little 0.5hp external pump like this one for $100. Might be a bit big on the flow side side of things but its easy to lose flow and impossible to make flow. My god where does any of this stop in the pursuit of the ultimate still.

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    0.5hp pump.jpg
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  • edited June 2014

    Or this one for $69. Anything external has to be better than those crappy pond pumps or submersibles that as grim said add heat to the water. Has anyone tried a decent sized car radiator with a fan on it, or the outdoor unit from an old split system ac unit, it already has a fan, its in a case, they have a reasonably big sized coil in them. All you need is a header tank attached to it and an external pump like this one and it should work.

    69 buck water pump.jpg
    105 x 105 - 3K
  • @grim. You did those flow tests yesterday, how many litres of water do you think it takes to do a run for those wanting to use town water? Might just end up with a really green garden.

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