Jump to content
ADI Forums
TuftedTurtle

Direct Fire Heat Up Problem

Recommended Posts

Still_Holler, when you say the sides of the still are insulated, do you mean the still itself is insulated (double walled)?

Share this post


Link to post
Share on other sites

I assume the bottom is not insulated and the flame touches the single layer of copper.

For safety reasons I am concerned about the wooden cladding with direct flame heating.

I had my direct fired still wrapped with a foil like insulation. I was planning to eventually wrap with fibreglass insulation then clad with wood.

Years went by then suddenly the "foil" went up in flames. It was just shiny plastic. No harm done because there was nothing flammable near by but it could have burnt the distillery down.

I have definitely decided against wood cladding.

Share this post


Link to post
Share on other sites

I'd be pretty concerned about the wood cladding as well.  Just to give you an idea of temps, with our jet burner we see heating surface temps of around 900-1000F at the bottom of the still, the ignition temp of wood is 375-500F.  A hassle for sure but you might really want to consider swapping out that wood for something non combustible like brick.  Because you have insulation on the sidewalls you are limited to only heating the bottom of the still and because of the cladding I would think you'd want very near flame contact and then have something like your power vent idea to draw out all the excess heat and bring in enough combustion air to feed the burner.  If you're going to keep the wood cladding I would use some ceramic wool insulation to seal  and insulate between the fire bricks/side of fire box and the bottom of the still so very little heat escapes near the wood so the still would sit on an insulating gasket essentially, not sure how well that would do it but something to keep the heat away from the wood.  

 

Related to the air, those jet burners really suck a lot of air.   ours is in an open stack of bricks from floor to the base of the still where we tighten the stack up to hold onto the heat. The power vent might be able to draw in enough air for good combustion, it'd be nice to test the idea somehow before dropping the coin one.  I'd also make sure the vent pipe is large enough diameter, I doubt 4" pipe is going to do it.

 

Good luck!

Share this post


Link to post
Share on other sites

Thanks for the feedback, you guys may have saved me a lot of trouble.  

I have the "aluminum" bubble insulation as well, PeteB how many years did yours last for?

I just asked the still manufacturer for the insulation type, which is Reflectix. I looked it up, It is rated for +180F. I called the insulation company and the engineer said there is very little flexibility in the heat rating and that it will melt if I bring the pot to boiling and I should remove it immediately.

 

Share this post


Link to post
Share on other sites

Wow!  That was a good call to follow up with the insulation manufacturer.  I'm sure the wood is slick and would be fine for an internally heated steam or even electric still but with direct fire it's just not the right material.  If you're pulling the wood, you could expand the brick base up the side of the still and maybe even set your vent up closer to the shoulder to take advantage of more heating surface.

Share this post


Link to post
Share on other sites
17 hours ago, Still_Holler said:

.................

I have the "aluminum" bubble insulation as well, PeteB how many years did yours last for?

..................

 

The insulation was there for several years before it "vanished in a puff of smoke" 

I wasn't next to it when it went up. Could smell hot plastic and went to investigate. In hindsight I am surprised it survived for so long. I possibly had the burner turned up a litter higher and the flame licked up the side of the still and caught the plastic foil on fire.

 

Share this post


Link to post
Share on other sites

To follow up: I installed power vents on both my vent pipes and have been getting a good draft with no problems. I removed the insulation and wood and did not replace it with any thing.  The insulation showed signs of deterioration and there was lots of moisture trapped against the inside of the wood.  I may end up going with a high temp, high moisture pipe insulation on the still, but the volume of water (200 gal) holds heat so well I see no reason to put it on the mash tun, it would just increase my cooling time.  (I was able to use the removed wood to face my bar with so at least its not a total loss)

Now I am running again I'm trying to figure the still out curious what you all think of these numbers?  It is 250 gal pot that has a 4 plate 6" column with dephleg on the top and 440,000 btu propane burner underneath.

Running pretty high flame I heat up 220 gallons 10 degree F every 15 minutes, or 40/hr.

Right now, I heated for 4 hrs with no water to dephleg and my kettle temp is 170 F but my column temp is only 78 F.  I heated it fast and then as I approached 160 I cut the heat way down but kettle temp is still slowly creeping up.  I would like to get the heads out with kettle at 170 (altitude adjustment of -3 F) then run on dephleg and higher heat to get hearts.  It seems like long time for column to heat up but I guess I'll have to be patient, possibly shut heat off for a little while.  

Share this post


Link to post
Share on other sites
18 hours ago, Still_Holler said:

Right now, I heated for 4 hrs with no water to dephleg and my kettle temp is 170 F but my column temp is only 78 F.  I heated it fast and then as I approached 160 I cut the heat way down but kettle temp is still slowly creeping up.  I would like to get the heads out with kettle at 170 (altitude adjustment of -3 F) then run on dephleg and higher heat to get hearts.  It seems like long time for column to heat up but I guess I'll have to be patient, possibly shut heat off for a little while.  

Not sure if this is what you are saying, but the boiling point of the wash is a function of the percentage of alcohol to water, you can't use the wash temperature as a proxy to attempt to distill out only specific components.  If your wash temp is 170f and your column temp is 78f, it's because you aren't boiling - the column/head temp will not begin to rise in earnest until you are boiling.  You would need to fill your kettle with azeotrope to be able to boil that low. 

Share this post


Link to post
Share on other sites

By the way, someone sold you a still wrapped in Reflectrix and Wood?  Knowing you were going to use it direct fire?  God I hope it's not a vendor on here.

That's the stuff they sell at Home Depot to staple up between your floor joists when you put in radiant floor heating - well, that's what I used it for anyway.

Share this post


Link to post
Share on other sites
20 hours ago, Still_Holler said:

Right now, I heated for 4 hrs with no water to dephleg and my kettle temp is 170 F but my column temp is only 78 F.  I heated it fast and then as I approached 160 I cut the heat way down but kettle temp is still slowly creeping up.  I would like to get the heads out with kettle at 170 (altitude adjustment of -3 F) then run on dephleg and higher heat to get hearts.  It seems like long time for column to heat up but I guess I'll have to be patient, possibly shut heat off for a little while.  

Ethanol-Phase-Diagram.jpg

Keep the heat on as high as you can until you reach a boil.  As Silk said your not hot enough.

Share this post


Link to post
Share on other sites

That's a lot of volume for 440k without a mixer, which is part of the delay. Once it gets going it should be fine.  I think the biggest problem as mentioned above, is that you have a thermometer in the pot, and you are looking at it. 

The only two devices you need to run the still are a thermometer at the top of your column, and a hydrometer in the parrot. You don,t really need the thermometer in the coulmn, but it gives you something to watch, other than the clock.

Crank up the heat

 

prost

Share this post


Link to post
Share on other sites

Roger, I know what you mean by watching the thermometer in the pot and it seems to take forever to boil, but that thermometer is very important to give you an idea when the pot is about to boil. If the heat is up too high at start of boil there can be foaming and puking issues. (but probably not such a problem with this particular still)

The other thing you say is essential is the hydrometer in the parrot. I don't use one because I do my cuts purely on nose. I don't want a hydrometer that might influence me to think the cut is at a particular ABV when my nose is telling me it is not.  I am making spirits that smell and taste great, I think of ethanol as just a byproduct (unless making vodka) . I use a cheap $30 refractometer to indicate when to turn the still off at the end of the run.

Share this post


Link to post
Share on other sites

Thanks for the advice all! I'm new to the bubble plate column still.  Unfortunately, PeteB I don't have much sense of smell, but I admire your skill.  I will have to rely mostly on the top of column thermometer and proof for my cuts.

So I have given it another run and I am getting very slow volume of product.  It is about 100/ml per minute.  What kind of volume are folks getting out there?

I was trying to run it faster to see if I could get more volume, so I turned the dephleg up and flame up; but I guess I turned the flame up too much.  The product flow would stop, temp drop, then condensate start slowly at high proof, pressure rising to 0.9 psi 1/2 hr later and proof would suddenly drop quickly and condensate overrun the dephleg and started spewing alcohol all over out of the vapor relief holes on the parrot. 

I got cautious after that happened a couple times and I would barely turn up dephleg water and then turn up heat tiny bit, and I would get steady flow of 100 m/l. After a 1/2-1 hr as proof started to drop toward 120 I would turn up slightly again and repeat. The proof would spike each time untill the heat increase caught up to the cooling water and then would even out at 100ml/min.  I turned it up incrementally 6 times but the flow never did surpass 100ml/min.  I got good yield of good product but it just took 14 hrs.

I am thinking to try again with the same small adjustments but be slightly more agressive with getting to a higher flame.

Is flow rate tied to alcohol percentage of the mash?  i.e If I do stripping runs and then use a 25% low wine for the spirit run will my flow rate be faster with the same heat compared to a 6% mash?

Thanks  

Share this post


Link to post
Share on other sites
On 11/6/2017 at 6:28 AM, Silk City Distillers said:

By the way, someone sold you a still wrapped in Reflectrix and Wood?  Knowing you were going to use it direct fire?  God I hope it's not a vendor on here.

That's the stuff they sell at Home Depot to staple up between your floor joists when you put in radiant floor heating - well, that's what I used it for anyway.

 When I told the still/masher manufacturer that the Reflectix engineer confirmed it was only rated to 180 F and should be removed immediatly his response was "never been a problem" and "its yours, it you want to remove it that is your choice"   I'm still in the process of rectifying quite a few problems with the manufacturer, so don't want to name names as it is a pending matter. 

Picture shows what I found under the wood.

015.JPG

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×