Typical Flow rate for 1/4" double-coil reflux condenser?

[joeymac]

I did a quick search and nothing immediately jumped out at me so I figured I'd ask...

what's the typical water flow rate for reflux condensers of 1/4" tubing construction?
(shortcut version: mine's about .8 L/min)

I'm considering replumbing my boka head for a better look and more control over individual processes and, more for curiosity than anything, I want put an inline flowmeter (http://www.amazon.com/dp/B0122QAEXM/ref=cm_sw_su_dp" onclick="window.open(this.href);return false;" rel="nofollow) in the mix so I can monitor my condenser flows too. Then I can do on the fly calculations and all that... I'm a nerd like that. Anyways, I had no idea what my flow rate through just the reflux condenser actually is. My pump drives coolant up the leibig product cooler, and then the flow splits to a valve-controlled bypass or the reflux condenser... the valve lets me pass more fluid through the leibig cooler than the downstream reflux condenser alone would allow.

Other setup info:
My heating is a 1800w hotplate driving a 2" column and my cooling is a Brewhaus 110v submersible pump circulating water through the typical 1/4" double coils you see in classified forums and on ebay (looks kind of like this: https://lh5.googleusercontent.com/-cB45 ... G_0682.JPG" onclick="window.open(this.href);return false;" rel="nofollow).



So I shut off all the bypasses so all of the flow from the pump went though the condenser coil only and it looks like it only flows about 0.82 L/min (or 13.7 mL/s). Seems kind of puny and once I open up my bypass some to allow more flow for the leibig, that means less pressure available to push through the reflux condenser than the rate I at which I just measured. Now I'm wondering if I should either upgrade to a higher flowing reflux condenser of 3/8" find a pump that can push more pressure. I mean, I know it works as-is since I've been using it for years...

[still_stirrin]

I've never measured the flowrate.

But I try to adjust slow enough so the temperature delta is close to the delta for the condensing vapor flows. The flowrates are very low due to the efficiencies of both my concentric reflux condenser and the shotgun product condenser.

I'd guess the combined flows to be at or below 1 lpm for a normal reflux run powered at 1.5-1.8 kW.
ss

[joeymac]

When I'm actually running the still, my combined flow is usually pretty high. This is only because I run my leibig output cooler and reflux condenser on the same cooling loop. I feared if I limited the flow of the whole loop to just what the reflux condenser could pass then by the time coolant got past the leibig it would be significantly heated before it ever even entered the reflux condenser... so the bypass lets more volume through the leibig portion of the loop. In the picture above, my coolant flows from bottom to top.

I guess I could just reverse the flow of my coolant. I know the ideal flow for the leibig segment is counter-flow... but the product is already liquefied in a boka reflux, so that wouldn't be much of an issue. However, reversing my flow would ensure cold water hits my reflux coils.

My best bet might be to add a 1/2" cold finger as the in-flow to my coils coming up and out of the head for less resistance.

[still_stirrin]

joeymac,

Your fashioned Liebig on the product is quite innovative...I like it. The cooling water should be counterflow, however, to work best with low flow.

And your bypass valve on your reflux condenser is a good way to regulate the RC throughput.

But I would recommend running the reflux and product condensers "parallel" from your cooling water circulation pump....that is, a separation T before running into the Liebig with the other branch connected to your reflux condenser inlet.

Then , you can collect the two water outlets for return to your water tank (or run through a radiator for additional cooling power efficiency).

Keeping separate flow controls will allow better tuning and water efficiency through both heat exchangers...you'll be able to approach maximum efficiency where the temperature differences are optimized.
ss

[joeymac]

Yeah, when I first built it awhile ago, I was going for simplicity. Simplicity meant less copper and less money, lol. Now I want to get a more streamlined and nicer look by rerouting the flow, ditching that plastic valve for a pair of nice brass ones, and adding an inline flow meter. I like the homemade leibig and reflux valve though so I'll keep those.

The more I think about it, the more I'm unconvinced the liebig flow direction really matters for me:
a) in a boka reflux the product is already liquid. There shouldn't much phase change inside the leibig.
b) Why does it matter if the product in the collection jar is a little warm.

[skow69]

If you can knock down the whole 1800 watts, and the bypass valve gives you accurate control, why mess with it? It sounds like you have a very workable system as is. You just need to build something. Make a parrot.

[joeymac]

Engineer by trade... I'm physically incapable of not messing with something even if it's perfectly fine.

Engineers:
If it ain't broke, keep "fixing" it until it is.

[Danespirit]

Engineer by trade... I'm physically incapable of not messing with something even if it's perfectly fine.

Engineers:
If it ain't broke, keep "fixing" it until it is.

....reminds me of my friend, who ....is a engineer.

I haven't actually measured my amount of flow in my RC every time i use it, but i would also "guesstimate" it to be a litre or even less per minute.

The more I think about it, the more I'm unconvinced the liebig flow direction really matters for me:
a) in a boka reflux the product is already liquid. There shouldn't much phase change inside the leibig.
b) Why does it matter if the product in the collection jar is a little warm.

I made a small Liebig for a LM solution: http://homedistiller.org/forum/viewtopi ... 4#p7298626
Yes, you are correct...no phasechange in a LM system (a Boka is also a LM).
My product usually is a bit warm. The more voilatile substances i don't want anyway, will evaporate.
If i want the product a bit cooler, i just put the collectionjar in a waterbath..
A extra valve for the RC is a good idea.
I run one on mine and even if the Liebig runs with full power from my pump (600 L/Hr), i can still regulate my RC to a point where it just cools the vapor enough to get liquid again.
Btw...you have a beautiful rig, Joseph..

[rad14701]

The general rule of thumb is that if your reflux condenser has a flow rate of 1 - 2 liters/quarts per minute you should be able to knock down just about anything you can throw at it... Some rigs are far more efficient and require far less than a liter per minute... YMMV...