Show Us Your Dragon

CothermanDistilling

I think it would be more important to direct the inlet and outlets a bit to eliminate this, I did this with The 4" Copper Cored Dephlegmator Attempt

jacksonbrown

You just can't cool saturated vapour without screwing with pressure. That's pretty basic thermodynamics.
Am I misunderstanding?
I meant what is the difference in temp above and below.
Are you saying that below the RC the vapour is cooler?
Are you sure there is no reflux in contact with the probe?
Are you sure the probe is long enough that there are no outside influences?
Are you even sure that the probe is of adequate quality that you can make those calls?

Like you say, the easiest thing is to try both ways and see the difference.
If you do have gas accumulating through the run then the available surface area for heat exchange will be reducing by a similar rate so you might even get an increase in performance at the end of the run. If you maintain the same water outlet temp through out the run that you normally would you should see a marked drop off in take of rate.

CothermanDistilling

the temperature in the RC tube is not uniform, so the first item is out the window.... near the wall is different from the middle..

CothermanDistilling

same way ice forms on the evaporator of an AC unit, but the air does not come out at 32F

jacksonbrown

RC tube? The vapour line? I think you'll find that's cooling from conduction heat through the metal of the probe. Rig it up so you've at least four inches of insertion and have the end of the probe a few mm off the opposing wall (while keeping it dry).

jacksonbrown

@CothermanDistilling said: same way ice forms on the evaporator of an AC unit, but the air does not come out at 32F

Sorry but it's actually nothing at all like that.
You need to read and understand that link I put up. I can't help any more than that.

CothermanDistilling

I understand completely, Please understand that there can be saturated vapor in the center of a RC tube, and liquid flowing down the side of that tube that is cooler than that saturation point... this cooled liquid will cool more saturated vapor into liquid as it falls, but as it goes down the side of the tube, it can either warm or cool depending upon the direction of the coolant flow through the RC.

DocPorter

I have to be honest I didn't read everything. Only skimmed, but this may help:

Logarithmic mean temperature difference @ Wikipedia

Read under assumptions and limitations:

A particular case where the LMTD is not applicable are condensers and reboilers, where the latent heat associated to phase change makes the hypothesis invalid.

That being said there is a certain amount of subcooling of condensed liquid, which is really how you decide cocurrent vs. counter in a condenser.

I run my defleg counter-current. My defleg cooling is a closed loop recirculation. It runs very hot and at a high flowrate. My reasoning for counter is that I want to decrease process vapor temp as it travels upward so I want the cooling to liquid to match as close as possible. Heat transfer is worse, but vapor temp is more steady and consistent and less liquid sub-cooling happens.

@jacksonbrown What you say about saturated vapor is correct with a single components system (like steam). However, we are looking a two component system, so there is a change in concentration rather than pressure. I think...

CothermanDistilling

isn't the product condenser undergoing a phase change also... well, it is, but is is also undergoing liquid cooling in addition, and that benefits greatly from counter flow...

I agree with @DocPorter, and that in a system that is doing complete phase-change and complete phase-change only, the two are the same...

In the RC, while taking product, we are doing 'incomplete phase change' and the orientation of the dephlegmator is backwards of what a steam system would be, where in something like a boiler jacket, you have a mechanism to drain out condensate so that the new steam can do it's job.

Kapea

Perhaps I'm missing something, but if there is only condensate (no vapor) exiting the product condenser at the proof you want, it's all good, right? Twiddle the control valve left or right as needed. The rest is just angels dancing on the head of a pin...

CothermanDistilling

hook your PC lines up backwards and see your cooling water efficiency absolutely plummet... if there is a diff in the RC, it is much less..

DocPorter

@CothermanDistilling That's exactly right. I run my PC in Counter-Current, because sub-cooling is desirable

Kapea

I didn't know you are in the Navy @CothermanDistilling, and a submariner no less! That explains a lot... ;)

Anavrin

An interesting conversation from a picture of my still :-)

I have it setup as counterflow as I can see the benifet of this method allowing more heat transfer between the vapour and the coolant for a lower flow rate of the coolant.

CothermanDistilling

think of it as using the warmest coolant to cool the hottest distillate, and the coolest coolant to cool the coolest distillate

image from wiki:

Kapea

FWIW I've been cooling my wort with counter-flow wort chiller (retasked AC condenser coil) for a couple of decades. Got one of these as a wedding present 20 years ago. The wife's gone, but the wort chiller still works like new.

Sunshine

@Anavrin, what did you expect? Just "nice still, keep up the good work"? :))

Kapea

My mistake, @DocPorter is the one air conditioning the U-boat (sub-cooling).

CothermanDistilling

@Kapea said: FWIW I've been cooling my wort with counter-flow wort chiller (retasked AC condenser coil) for a couple of decades. Got one of these as a wedding present 20 years ago. The wife's gone, but the wort chiller still works like new.

I have that same chiller from hearts, bought about 12 years ago, recently, I used it as a post chiller back in the daywhen using my PDA-1 as a stripper on a 40 gal water heater, massive efficiency when used that way, but the corrugation causes smearing, but not an issue in stripping...

I have been pushing for convoluted tubes in heat exchangers for years here, right boys?

CothermanDistilling

Oh... anyone in FL can get a similar one for free by taking the commonly disconnected 'AC superheat recovery box' that is on the outside wall of many homes in FL apart and using it, same coil is in the box along with a taco pump and some snap switches... they pipe the freon from the AC unit into the box, and when a snap switch gets to 180, it turns on the pump, and water pumped from your household water heater via the little taco pump absorbs the heat.. you can get your water heater to 180 with the right mods, but you need a tempering valve to bring the exit of your water heater to the house below 140...

I can't help but using the same thing to preheat wash while chilling a cold liquor tank...

marcus

hello just a update, from the small 8" column still we built last year as a test to see if a column mounted on the floor would work, we have now up scaled to a 600mm twin column 2500 litre pot. we are fitting it all together the first of two columns are built and the pot is in.

jez

Hi all,

It's a working progress but it's getting there and I'm eager to use it for the first time.

jacksonbrown

Looking good! Fire that baby up!

jez

@jacksonbrown oh I will as soon as I get a spare day to sit play and learn oh and try the new electric parrot that I received today :) :)

FloridaCracker

Lotta toys you got there Jez. Let us know how it all goes; the good, bad and the ugly.

grim

Sweet rig

Kapea

I like the ethanol CEMS sensor you have T-ed in there @jez. Let us know how that works out for you.

punkin

That there is the first production model electric parrot from SD. Congrats Jez looks the goods.

I'd put the tee before the product condensor, it will work very well for the parrot and will lower your takeoff by 200mm.

rossco

So are they available yet Punkin?

punkin

There are a couple mate. I'm just waiting on some photos to list them on the site. The parrot kit with probe and either 1/2" or 3/8th compression fitting will list at $390. There will be more stock in a few weeks and we are hoping to get the price down a bit in the long term with better sourcing of the expensive parts if the sales numbers make it possible.

Give me an email or PM if you want one and i'll see what i can do. I'll tell you one thing, once you have used it you won't be going back to relying solely on an alcometer. $20 lottery ticket on that one.