Condenser / Dephlegmator Temperature Monitoring

[Son of Opus 27]

I am tinkering with the still setup and have a couple of queries / questions in regard to setup of the condenser and dephlegmator.

In regard to the dephlegmator I plan on using the hot output from the top feed of the product condenser to feed the dephlegmator the plan is to put this feed into the top of the dephleg so that the top of the container is cooler than the bottom as the water will heat up as it descends is this right.

The second question relates to temperatures and monitoring if I monitor the output from the product condenser what temperature does the feed to the top of the dephleg need to be at I am assuming that it wants to stay below 195F / 90.5C to effectively limit tails coming through.

The third and final question a the moment relates to the water out of the bottom of the dephleg is it useful to monitor the temperature of this output or is it not going to be overly helpful.

Cheers
Nick

[Anavrin]

Hi Nick

It all depends on how efficiant your dephalmator is if you want to run the two in series.

I deally you want to be able to adjust the water flow in your product condensor so that the product being collected is at 20°c, this ensures your parrot gives accurate readings.

Also the dephlagmator needs to be able to knock down all the vapour and produce 100% reflux return.

If the two aren't matched in the sense that your dephlag needs a high flow and your product doesn't, you won't be able to run them together inline, you can of course run the product too cold, just so long as you can control the reflux.

So far as temperature goes, I've tried measuring the temp outputs from both the deflag and the PC but it doesn't really tell you anything because next time you run it, your mains water will be at a different temp due to the time of year.

I think the best place to measure temp is in the parrot and just above the deflag in the pipe bend, in theory you start with the deflag on full, then slowly close off the supply to start allowing vapiur through to the PC, if the probes above the deflag, it should read pretty close to the vapour temp, adjust the deflag to give a temp of 77°c to take heads off, then start decresing the water flow some more to increase the temp to 80°c ish for hearts, I'm still learning a CM setup myself, it might be a good idea to go on the StilDragon forum, most of the guys on there run SD stills, the majority of which are CM, there's also some manuals written for running the SD dash colums that are 4" with a few bubble plates, and similar to your setup.

http://www.stilldragon.org for their forum

[Son of Opus 27]

Thanks for that Anavrin, the product generally is probably at the same temperature as the tap water going in at the bottom. Probably only the first 2-3 inches of the product shot gun is noticeably warm, so I will warm it up more by reducing the flow so will have to take some temperature readings of the essential oils that are collecting.

The Dephleg is not a shotgun but a copper coil with copper packing (lots of cut up 10mm od pipe) around it so has no difficulty creating 100% reflux I should not have an issue feeding it from the PC. I also plan to have couple of valves in the pipe work to adjust the amount that goes through the dephleg or whether it leaves the system first. Initially on startup I can send all of the water from the PC through the depleg and at that point the water will be cold as no heat will reach the PC.

I have just put a thermowell in the boiler side of the top bend so will be able to monitor the temperature of the vapour coming over to the PC which I had not been able to do before.

I think I will still check the temperature of the water leaving the PC to feed the dephleg as this will give me an indication of the relationship of the water temperature and the temperature of the vapour.

Will also do some further reading on the Stilldragon site.

Cheers
Nick

[Phantom]

It took me a while to picture what was being alluded to.

I suspect that Anavrin has got it spot on.

There are designs kicking around, where the outlet (the hot end) of a liebig condenser is designed to run through a reflux column (sorry I can't get used to using the dephlegmator term, however correct/accurate it may be), but it seems like it's usually used instead of packing in the column, which I suspect, is more about the difficulty of getting the packing into the column after the tubing has been installed.

The tubing would help some with refluxing, but not as much as packing.

I'd guess that if you built/adapted a column so that you could make use of the heat transfer from the water flow, then mesh packing would be out of the question, and you'd have to make sure that you had enough space to use SPP, rashig rings or similar down the sides of the tube. Something inline to stop that granular type packing dropping out of the column.

So, say you designed it so that the outlet of the product condenser did indeed pass through the column (however many times you wanted etc), then the main diameter of the column body/riser area might have to be a good few sizes larger - say you used 15mm pipe for the heating exchange water flow path, then the main body would likely have to be something like 75mm pipe so you could install and remove the main column packing (as alluded to above).

Then there's the issue of the water temp as it comes out the condenser. Is it cool enough to help with refluxing ? or is it warm enough to just reheat cooling vapour as it passes the pipework ?

If you look at CM designs, like a T500 for example, it's a very delicate balancing act that has been researched heavily for commercial production (delicate because tiny changes in cooling water flow can cause quite wide temperature swings in the column, causing instability in the column and likely smearing any cuts you're aiming to do).

I'm not saying it's a bad idea, just that there's better ways of designing how you incorporate elements to provide the refluxing facility. Many have pro's and con's (still dragon designs often have bubble caps etc, to provide refluxing, which on the face of it is good - as it's aesthetically pleasing as well as efficient, but it's the one way I know of, that with refluxing, allows for flavour retention, which is fine if you're making flavoured spirits, but less so if you're aiming for clear/neutral spirits).

Hence it depends on what you're aiming to do/produce as to the design that's gonna be most efficient......

I think that lot makes sense (it does to me)..........

[Easydrinker]

After a couple of read throughs,I think what you say makes sense to me Phantom.
Your logic seems sound.
But I have got a wobble on,and about to stagger to bed

Robert.