cooling requirements

[StillSober]

Hi Everyone (first post), thanks for the forum site, seems great.

I'm in the process of designing and making a reflux still.

I'd like to ask about the adequacy of the cooling I have in mind.

Boiler: 10 to 15ltrs
Heater: 2000W induction plate with 200W step settings
Column: 2.5" x 1m high
Condenser: Liebig with inner 12mm, outer 19mm x 600mm long
Reflux condenser: 3m x 12mm coiled copper tubing at the top of the column.

So what I had in mind was a 30watt submersable pump in a plastic 200ltr drum. Most of the flow going through the Liebig and with a tap to control the flow in the reflux condenser coil to control the reflux.

So how much water would I need to put in the drum?
What is an acceptable temperature rise for the cooler water?

Many thanks

[CaptainRedBeard]

You should drop by the Welcome Centre first and say hello, tell us who you are and what your distilling dreams are.
As far as your build goes, I personally would make the column a bit longer, 1.5m to the take off, more room for packing. Then the additional 300-400mm above the take off to fit your RC.
Your leibig length and size is the same as mine, does the job.

But I'm only a noob, so take what I say with that in mind 8-}

[CaptainRedBeard]

Well now I do feel like an idiot. Threw the tape over my reflux. 1m from boiler to the T-section. Then 300mm above the T. 8-}
Your design looks good then.
As for your cooling method, I can't help you there, I just run off a 3,000L water tank.

[Meatheadinc]

Hi

for purity make the column length as tall as possible - ceiling height - a bit :))

200l cooling on 2000w reflux will heat up. I used a similar set up
if only planning single runs of 10 liters it might do, but will require time for your cooling reservoir to cool before a new run. and adjustments to flow will need to be made as temp rises.
ideally you will need a cooler of some sort or a larger reservoir

[Meatheadinc]

realistically you will need a bigger tank or an efficient cooler

[StillSober]

Thanks for the replies.

@Cap'n: I'm using 1000mm column height also, because the nice stainless tube (brand new exhaust pipe) comes in that length. $53 delivered it's 63mm OD, with 2mm thick wall. From what I read, it seems that over 600mm and the purity gains are diminishing returns on the extra length of column used.

@MH: I suspected this might be the case. I'm reading "The Compleat Distiller" by Nixon and McCaw. It has a scientific approach to quantifying things. Power input, together with water mass and time should yield temperature rise. I'll try and calculate it and post back my results.

I have an old car radiator that seems in good condition. I could have the return water flow through that and ceiling fan push air through the radiator. I might need a bigger pump for the required pressure though.

[BIG D]

Hi mate and welcome . I have just rolled a 12.7 mm copper coil and I think you would be hard pressed to roll it tight enough to fit inside 2.5" I would consider 1/4" if that is your intension .Maybe a picture of your proposed design if your looking for input. :think:

[Meatheadinc]

I have used I car radiator and was not happy with its efficiency on long and multiple runs.
I now use a AC split system radiator with the compressor removed.
this AC system is rated at 9KW and does not get warm with approx. 3kw of still heating power.

cooler.jpg

keep an eye on the tip and recyclers

[StillSober]

Thanks BigD, I've tended to limit myself to what's available in Bunnings for copper materials. I've used this coil calculator http://deepfriedneon.com/tesla_f_calchelix.html and yes, 3m makes a long coil, it would probably need to be a coil within a coil so that it does not take up too much of the column. I'll definitely consider the thinner tubing. I'll make a detailed drawing of my design.

MH: is that a 90ltr bin and is it full to top with water? Is the split system outside box minus compressor easy to get hold of by the average punter? I guess having oversized cooling has a big advantage of negligible temperature rise and adjustments to condenser flows during a distillation run.

[Meatheadinc]

SS the bin is a standard 220l wheelie bin holding approx. 200l
it is great having an oversized cooler, as you said little to no adjustment required.

availability is hard to judge i would suggest talking to the local aircon guys as they takeaway old systems when they replace new ones.
i got mine this way and free of charge. bloke was happy not having to load it on the truck. ( bloody heavy with compressor, light once removed)

[Meatheadinc]

I have a spare 1/4 double rolled coil approx. 10inch long. if your nearby its yours ( pm me) I stopped using it when I move to recirculated water as it was too restrictive and added too much back pressure for the pump system (750w submersible) the problems were solved with the addition of a cold finger

[StillSober]

Thanks for the kind offer, but I'm not near by.
What is "cold finger"?
How would you compare the heat transfer requirements of a reflux coil in the column with that of the Liebig condenser?
I've been assuming (maybe wrongly) that the reflux coil is throttled back because only a portion of the vapours present need to be condensed whereas 100% of vapours on the output need to be condensed.

[CaptainRedBeard]

I've been assuming (maybe wrongly) that the reflux coil is throttled back because only a portion of the vapours present need to be condensed whereas 100% of vapours on the output need to be condensed.

This depends on the type of reflux still you operate. In some, the reflux coil can be manually shifted up and down the column to prevent a percentage of vapors from entering the takeoff, and the water flow is not adjusted or "throttled". In some where the reflux condenser is located in the column, before the take off, these are generally controlled by water flow to alter the percentage of reflux.

[Meatheadinc]

I may have my terminology slightly off but this is what I was talking about

coldfinger.jpg

Left is 1/4inch pipe double wound with 1/2 cold finger. - water enters 1/2 and returns via 2, 1/4inch coils running parallel to increase flow and reduce backpressure.

Right is 1/4 inch double coil - water down centre coil and up on the outter

hope that helps

[BIG D]

I may have my terminology slightly off

Meaty your terminology is spot on mate. ;-)

[StillSober]

MH, thanks for the pictures, that makes it clear. I read that Cold Fingers are used to allow greater flow of coolant and why you'd need that with 750W pump!
I also read in Compleat Distiller the rule of thumb: 1kW boiler raises cooling water flowing 1ltr/min by 14degC. My 30W submersible will pump more than 10x this flow rate. So if 10ltrs is being raised by 1.4degC every minute the 200ltr drum will warm up. So after 1hr the whole drum could rise by 4 or 5 degC.
I think Vapor Managment controls are less sensitive to coolant temperate but I'm not sure if 15degC over a 3hr run is doable?

[Meatheadinc]

I use a 750w pump to cover for head height and ability to prime a dry system. It as allows for extra flow (bypassed) to pass through my cooling system.
The 750w easily feed the double coil, I was unhappy with the amount of back pressure on the pump so a new coil with cold finger was made.
I also mucked around with smaller pumps for aquariums and fountains and was not happy with the performance they offered

coolant water, providing you have enough surface area and flow, can still knock down vapour above 40C however I think you will find that the coolant water in the reservoir will heat up at an expediential rate and not in a linear fashion as in your equation. although you may be able to utilise the this system for a single run (10-15l), it will require increasing flow rates during the run and long cool down periods between runs.

[StillSober]

I'll do a small run (cleaning runs) and get a feel for things.

Here's a thread with my first plan:http://www.aussiedistiller.com.au/viewtopic.php?f=29&t=7180

[gemini2544]

I'm A noob too & asked this same question this morning (not seeing yours) I was stunned at the amount of cooling water needed. I'm so glad that one of my sheds has a full 5000 liter tank next to it & the same shed has 240 volt power, I now just need to do some creative plumbing. :D

[twentytwo250]

I have just purchased a Neutralizer and am looking for the simplest condenser hookup. My intension is to feed water from the water main into the 2" condenser out into the 4" condenser and then out of the 4" to the sewer. My question is, would the water from the 2" be too hot for the 4" condenser, and what flow rate should I use.