Which one has more reflux? Stainless steel or copper?

[spiritdistiller123]

Hi there,

I have some questions.
I am a little confused between copper and stainless steel(SS).
I know that copper transfers heat better that SS.
So, I want to know in a reflux column distiller which metal plays a better role in the reflux issue?
which type of helmet do better reflux, copper helmet or SS helmet?
and also packing!!
I want to use SPP packing for my column. I want to know which metal to use to get higher proof of alcohol.
which type of SPP packing does better reflux, copper SPP or SS SPP?

In my point of view, copper plays a better role here and higher proofs could be achieved with copper with respect to SS. because it conduct the heat just like heat sinks and we have more reflux inside the column or helmet or packing. but I'm not sure!

thank you for your kind help

[shadylane]

From a practical stand point.
SS spools are the easiest to acquire and use.
4" dia copper tubing is hard to come by and then there's the problem adding ferules.

I think the copper tubing would have more unwanted passive reflux. That's not a good thing,
We want the reflux to start at the top of the column and drain through the packing.
Reflux forming on the walls of the column will lower the overall performance.
Insulating the column helps to increase the columns performance

[spiritdistiller123]

From a practical stand point.
SS spools are the easiest to acquire and use.
4" dia copper tubing is hard to come by and then there's the problem adding ferules.

I think the copper tubing would have more unwanted passive reflux. That's not a good thing,
We want the reflux to start at the top of the column and drain through the packing.
Reflux forming on the walls of the column will lower the overall performance.
Insulating the column helps to increase the columns performance

thank you for your answer

what do you mean by unwanted reflux? why it is unwanted? supposed that we have a column full of SPP, why the reflux from the walls is unwanted?
So you mean copper do better reflux than SS but it is unwanted reflux and leads to lower alcohol proof? is it true?
what about SPP? which kind of SPP acts better? Copper or SS?

[tiramisu]

How much reflux you get has little to do with copper vs. stainless and a lot to do with the surface area.

Column shape, onion etc effect what temps the reflux takes place at and can affect flavour.
Quite a few masters thesis on the impact of column shapes on taste and ester/chemicals that have key flavors outputs.

Copper is a popular reflux material in order to reduce potential Ethyl Carbamate (urea/thane(?))
Although it could be argued that you would be better off focusing on not creating the urea in the first place by not stressing your yeast rather than stripping it out in the end.

Popular opinion seems to be you can't go wrong putting some copper in the vapor path to act as a catalyst but this isn't a discussion of
which has more reflux.

Alcohol on its own, is a much higher risk factor than Ethyl Carbamate. In the quantities responsible drinking is consumed at, Ethyl Carbamate in spirits becomes a non-issue (expect for fear mongering and unscrupulous marketing purposes to promote or justify stills for potable spirits that excludes copper to reduce costs)

On the other hand Copper is magic

[Twisted Brick]

Column shape, onion etc effect what temps the reflux takes place at and can affect flavour.
Quite a few masters thesis on the impact of column shapes on taste and ester/chemicals that have key flavors outputs.

I've seen a number of articles on how the shape of pot stills reportedly affect distillate flavor, but not come across any on how column shapes (dimensions?) affect flavor in reflux stills. Any papers you could recommend?

[still_stirrin]

...what do you mean by unwanted reflux? ...why is it unwanted?.. <— As Shady said, “passive reflux” is unwanted, because it occurs along the walls of the column instead of above the packing.

“Reflux” is the process of condensing vapor and reboiling it by rising hot vapors. This causes the vapor constituents with a lower boiling point to rise to the top of the column while, constituents with a higher boiling point (water) to condense and return down the column, or even back to the boiler. The process of reflux is enhanced by the contact of condensate and vapors on the packing materials, so yes, packing material matters to the efficiency of the column.

...supposed that we have a column full of SPP, why the reflux from the walls is unwanted? <— I hope my explanation above answers this question for you. Condensate accumulating along the walls of the column would simply “wick” down the column and wouldn’t effectively intermingle with rising vapors.

So you mean copper do better reflux than SS but it is unwanted reflux and leads to lower alcohol proof? is it true?
what about SPP? which kind of SPP acts better? Copper or SS?<— There are many types of packing (materials and shapes). The purpose of the packing is the heat exchange process between rising hot vapors and falling cool condensate. Copper is a good conductor of heat while glass and even scoria (lava rocks) are good insulators. Some of the best packing is scoria, simply because of the surface area of the chunks and the ability to transfer heat from the vapors to the condensate.

There you go...a brief lesson in reflux distillation and (hopefully) some answers to your questions. Purity is increased by multiple reflux cycles (condensing and reboiling, etc.). A higher reflux ratio will improve purity, separating the water from the alcohol and other volatile components.
ss

[Birrofilo]

Copper and SS have different pros and cons usually not really related to heat transfers unless we talk final condensers.

Copper can be easily worked and people with some practice can self-build a copper still. Stainless steel, not so.
Copper requires more and more complicated maintenance and cleaning, SS is easier to clean and keep in order.

Copper is shiny, is bling, and makes good still porn. SS is plain and says "industry" not "artisanate", it says "prose" not "poetry". But my still is SS. I'm prosaic.

Some copper is usually (but not universally) deemed advisable in the process but that can be satisfied with a little copper in the vapour path.

Reflux depends more on the surface than on other factors such as material.

Helmets: I don't know but I would say that in order to have the same reflux with a SS helmet one probably need a slightly larger SS helmet than a copper helmet.

Final condenser. I think this is where copper can make a difference, copper knocks down your vapours more easily. If you have a Liebig condenser, a copper one will dissipate more heat than a SS one of the same dimensions, so if your condenser is a Liebig type, or a simple air-cooled long cannule, than copper is best or it allows you to save space.

I have SPP and I bought it in SS rather than in copper because I presume the working in the column is almost exactly the same. I do have some copper in my column already and I wanted to avoid the additional cleaning hassle.

[spiritdistiller123]

There you go...a brief lesson in reflux distillation and (hopefully) some answers to your questions. Purity is increased by multiple reflux cycles (condensing and reboiling, etc.). A higher reflux ratio will improve purity, separating the water from the alcohol and other volatile components.
ss

thank you so much this helped me a lot

[spiritdistiller123]

Final condenser. I think this is where copper can make a difference, copper knocks down your vapours more easily. If you have a Liebig condenser, a copper one will dissipate more heat than a SS one of the same dimensions, so if your condenser is a Liebig type, or a simple air-cooled long cannule, than copper is best or it allows you to save space.

thank you for your answer

What about shotgun and coil condenser?? I think SS performs better than copper there. what's your opinion?

[still_stirrin]

What about shotgun and coil condenser?? I think SS performs better than copper there. what's your opinion?

Copper is 7.7 times better at conducting heat than stainless steel. For this reason, copper will always “get the nod” for use in a condenser unless material interaction is a concern; highly caustic or acidic fluids, for example. Stainless steel is much less reactant in harsh environments than copper is, as copper will tend to ionize in acidic and caustic conditions.

But, copper’s heat conductivity is a big advantage when the desire is to transfer heat, from a hot vapor to a cool liquid like water. The energy moves quickly from the vapors through the copper tubing and into the water. However, you must consider the tubing’s “wall thickness” because that is a key feature of the heat transfer equation as well.

Since stainless steel is stronger than copper (in both tension and bending), you can get away with a much thinner wall for the tubing to hold the same line pressures. However, the strength is not 7 times greater such that copper is still better for use as the condenser’s vapor tubes because our operations simply won’t see or need to hold high operating pressures.

Heat conductivity, therefore, “wins the design advantage”, albeit capital cost not withstanding. Copper is certainly more expensive than stainless, so many users choose it “for purchase” without consideration to function.
ss

[Birrofilo]

What about shotgun and coil condenser?? I think SS performs better than copper there. what's your opinion?

A coil condenser would typically be made in copper but a SS will certainly work, again with a bit more effort in lenght and space.

A shotgun is normally so "powerful" that will work very well also in SS. I have a SS shotgun final condenser which is way more powerful than needed. I have a 2000W or so stove under my 35 litres kettle. This is my final condenser:

https://www.stilldragon.eu/en/condenser ... -long.html

If you buy them you can ask the producer the rating which is in Watts of istantaneous heat they can dissipate (given sufficient water).

If you build one yourself in copper, that lenght will certainly let you knock down anything that can be produced by a still like mine, without need for calculations.

Basically, for a Liebig condenser you should calculate a bit if it is sufficient or ask here about advice.

A copper coil condenser and a SS shotgun will be sufficient if you just follow the normal dimensions that you see in pictures of stills, you should have no problems unless you grossly undersize your final condenser. Just keep the normal proportions that you see around.

Copper is more conductive than SS but the relative advantage is less than what appears from the conductivity differential. In homebrewing it is known that a copper immersion cooler is better (faster), but not radically better than a SS immersion cooler. I think this is because extension of the exchange surface is more important than the conductivity of the material. It is clear though that copper will always perform better than SS, coeteris paribus.

[spiritdistiller123]

Copper is 7.7 times better at conducting heat than stainless steel. For this reason, copper will always “get the nod” for use in a condenser unless material interaction is a concern; highly caustic or acidic fluids, for example. Stainless steel is much less reactant in harsh environments than copper is, as copper will tend to ionize in acidic and caustic conditions.

thank you so much
actually I care about the interaction of copper with acidic fluids!! I think this issue should be considered while building final condensers. am I right?
you said heat conductivity wins the design advantage! So I figured out from what you said that if you want to build a condenser you will choose copper! why didn't you consider the interaction of copper?? why you don't care about the interaction of copper with the fluid?

[spiritdistiller123]

A shotgun is normally so "powerful" that will work very well also in SS. I have a SS shotgun final condenser which is way more powerful than needed. I have a 2000W or so stove under my 35 litres kettle. This is my final condenser:

https://www.stilldragon.eu/en/condenser ... -long.html

If you buy them you can ask the producer the rating which is in Watts of istantaneous heat they can dissipate (given sufficient water).

If you build one yourself in copper, that lenght will certainly let you knock down anything that can be produced by a still like mine, without need for calculations.

A copper coil condenser and a SS shotgun will be sufficient if you just follow the normal dimensions that you see in pictures of stills, you should have no problems unless you grossly undersize your final condenser. Just keep the normal proportions that you see around.

thank you

your condenser is great!!
you can see my final condenser and dephlegmator (reflux condenser) below! the left one is final condenser and the right one is dephlegmator. I have build it myself.
the diameter is 2" and the length of final condenser is 700mm. the volume of my boiler is about 40 lit.
I made the condenser a little long in order to consume less water and it works perfectly. my outcome is about 20 degrees Celsius. any comment?

[Birrofilo]

@spiritdistiller

I think your final condenser is certainly able to knock down whatever you give it to knock down!

[spiritdistiller123]

@spiritdistiller

I think your final condenser is certainly able to knock down whatever you give it to knock down!

thank you for taking your time