Distilling Craft
Distilling Craft
You Only Still Twice
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We talk with Chip Tate about his new venture Tate & Company Distillery and the pot stills he is creating on-site - designing them, fabricating them, and using them. Later in the episode we talk about the anatomy of a pot still.
You're listening to Distilling Craft, Episode (7): "You Only Still Twice". Today, we're going to be talking with Chip Tate of Tate & Co. out of Waco, Texas.
Podcast PromoDistilling Craft is brought to you by Dalkita, a group of architects and engineers who specialize in designing craft distillery across the US. More information is available at our website dalkita.com [ d a l k i t a.com]
Colleen MooreHello everyone. Welcome to Distilling Craft- I'm Colleen Moore. Just a quick thing, before we start today's show. While we're hard at work, lining up new interviews, producing new shows, and you are so kindly waiting on us - we're going to reissue a couple of our episodes from season (1), with some previously unreleased material mixed in. We revisit episode (7)- from season (1) with Chip Tate from Tate & Co. in Waco, Texas. Chip was formerly with Balcones, but he's now firmly in his second act with Tate & Co., a distillery and a copper works where he's designing and building his own pot stills. Later, our radiogenic part-time distiller - DJ talks about the anatomy of a Pot Still. Welcome to the show, Chip.
Chip TateThanks!
DJ for DalkitaSince most of your day is spent making stills right now, I figured we'd jump right into some of the technical aspects. What kind of stills are you making?
Chip TateWe make pot stills. I've always used and been partial pot stills, so that's what we make the copper works. There are other great companies that make columns, but that's just not our thing.
DJ for DalkitaI know, in the past, you've been a proponent of direct fire stills and, obviously, there's some engineering aspects around how to work a direct fire still into the distillery. Can you talk about some of what you're doing with direct fire?
Chip TateThe advantages most people are, or at least a little of are, aware of in terms of the flavor development that can happen. It always depends on what you're distilling, of course, in terms of what those flavors are that can be developed during the first distillation. From my standpoint, during a second distillation or third distillation, it really doesn't make that much difference other than an evenness of heat which could be done any number of different ways including, but not limited to direct fire. We've got our first distillation done via direct fire. The challenge there is, some of it you've just got to make the stills thicker, and more structurally robust because of all that heat stress. Then, there's a wear component in terms of typically you've got some kind of mixing. We have a unique mixing systems, I won't go into right now. But, the advantages, they don't have any friction other than just the swirling motion of the liquid to where the stills down, which is a major factor. Most people are using agitators or even rumagers, which will of course wear down the thickness of the bottom of the still as they scrape over the years. The final thing, you don't really think about too much until you do a direct fire, still especially above a certain size, I'd say above 200 or 300 gallons, is the structural component of making sure that you can support all that weight and a very hot oxidative environment. Things like steel, that we usually use for structure, started to get a little unhappy when they get above 700- 800 degrees constant duty. So there's some challenges there too.
DJ for DalkitaWith the flavor development, are you mainly talking about formalization, or what are the flavor developments you see happening on the first pass?
Chip TateMaillard reactions, Amadori reactions, the caramelizing, the browning effect- caramelizing effects are in that class of reactions. But, many of the sorts of flavors that we associate with freshly baked bread or with beer for instance, or actually the production of Malliard reactions in the kettle, or sometimes in the malting process. But either way, those hotter temperatures are necessary to create those flavors.
DJ for DalkitaTypically those reactions are occurring on the sugars themselves.
Chip TateSugars and proteins. This is a kind of oversimplification but, in general, you're talking about simple sugars, simple proteins , aqueous solution and not add 200 degrees- 400 or 500 degrees, so that's the sort of thing where you need an elevated heating surface temperature to achieve that, obviously, with any sort of standard high pressure steam, I mean, even high pressure steam, you can only get to 300 and chain, it's all going to be a function of the pressure of the system. But you can't really practically get to 500 degrees. I don't know what the steam pressure would be at that temperature, but I'm pretty sure it's off the chain. It's probably 25 bar or something like that. Something off the commercially acceptable scale.
DJ for DalkitaAre you filtering your washes before you run them into those stills? Are you trying to remove the grain and east things that are burning at that temperature?
Speaker 3A malted mash- like some people do. In other words, if it's a malted, typically, malted barley, then we'll use a mash lower tend to separate them, but in other cases now, any sort of core whisky, if we were to do other small grains, even something I might do with fruit that might have some solids in it or something, we will keep all that in.
DJ for DalkitaSo, you're just relying on the agitation then to prevent the burning of your non art solids- the proteins.
Chip TateRight. We have the system. Again, I won't get too into it right now, but it uses a carefully done re-circulation process, to keep fluid moving along the bottom on the heating surface. The point is that other than maybe assisting convection a little bit and heating faster from a burning standpoint, it's making oatmeal. It really doesn't matter whether you start at the top of the pot, it matters if you started the bottom of the pot. So that's what that system is focused on, is to keep things moving at the heating surface.
DJ for DalkitaSo, the other big problem with direct fire is the safety. How are you looking at either the venting, the chimney effect on your direct fire, or renting a possible leaking the still to causing problems?
Chip TateOne thing I always like to say is that, "You're right but with some caveats". Potentially, one thing that makes a steam still safer, which we also use, is the lack of an ignition point, in terms of an open flame. Of course, one thing that can make a steam still less safe is this lack of an ignition point, because you don't want anything to burn or explode. But if it's going to, there's some places that it's better for to do that than others. For instance, if you had a well designed firebox, the still were to leak better than it leak in there, you've got a well ventilated fireproof space. The same sort of thing, you still have to constantly inspect your stills and make sure everything's good and do all the things to still it should do, to make sure that their equipment's still in good condition, make sure that there's no panting, which is as the still ages and gets thinner. You can actually use this comes up to pressure, you can see the shoulders expand very slightly, which just means that the coppers standing out there with the vapor hits it. But, the main issues on safety is that you have to do a thicker still, mostly for thermal stress, but then the flip side of that is, in our wash stills we have probably seven, eight thick, very carefully welded and tested weld, which makes it less likely than a thinner piece of metal to leak- all things being equal. I think a lot of the safety issues, honestly, are pretty similar. The only other real safety issue is structural. Making sure that whatever supporting the still can handle the temperatures and the weights. That's a bit of a trek. So, we use some pretty exotic stainless alloys and cooling systems to make sure that the support structure for the still doesn't fatigue and eventually give way. You can imagine what happens if the still crashes down on top of a burner or something, it's not good. It probably just means the still will stop the stilling, but it could be worse than that. But, I think, that most of the really important safety things are consistent across all types of stills. And, I think, that the most important thing is good ventilation and good ethanol sensing. Because one general engineering principle is true If you can make sure that air is moving and not coalescing anywhere, and the alcohol level is below a certain amount, you're not going to have a fire. That's pretty basic because all equipment will eventually fail. The question is what happens when it does?
DJ for DalkitaThat's exactly it. What are you doing with your stills to help control and influence the flavor they're producing? I've read a bunch of papers on the shape of the head- everybody talks about the line arm and inclined versus declined. What are you doing to look at? What do you think is important?
Chip TateIn many respects, the stills we do are pretty conventional. Some of the particulars, for instance, my spirit stills have double steam jackets, which allows me to heat things up more quickly and also only heat from the bottom and a more gentle way later on in the distillation, like jets, or planes I guess, or a lot like stills that you don't make them act a certain way, but you do create a set of possibilities. Technically, you can make vodka on a pot still, just you can dig a swimming pool with a garden spade, it aint the easiest way. Now, that's not an argument against pot stills. Pot stills are really good at doing other things, that column stills, in my opinion, aren't as good at, for the same reasons- they're different tools. Really, it's going to come down to creating a still where you can run it. It's the control factors that she really need. I mean, setting a pot still system things are going to be set up to operate pretty smoothly inside of its certain reflux range. Just like different air frames are set up to fly well under certain circumstances. It's not to say that you can't make them go faster than that tool point, or make them go slower than that tool point, but they may struggle. That something takes a 747, it's meant to carry a whole lot of people very safely at a relatively slow speed for a jet. There's a lot of things that plane is designed to do well, but make really sharp tight turns in one of them, because you can't have all of that. The same sort of thing with our stills, they're really designed around both the heating system. So it's going to be the cooling in the room, the shape of the still, the thickness of the metal, and the heating system you put on it. Because the natural reflux you build into the still is going to depend in part on how quickly you're running it, so almost all pot stills if you've got a big enough heat under it, it really doesn't matter how they're shaped because you're just going to blasting vapor up through the top of it. Then, others that when you slow them way down, the more upward ascent you have, the more transient turbulent mixing you have, the more potential there is to create a much higher reflux situation. Do you want that or not? How stable is it? Where do you need it to be? It's very much like designing an air frame that way, because when you drop below that stall speed, the analog therefore for potstill is going to essentially be the equilibrium point, where the amount of cooling and hating going into exactly the same. And for some stills, column stills set up on equilibrium pretty easily because once they get going, because they're meant to do that, pot stills can be a little more finicky depending
DJ for DalkitaWhat are you doing with the cooling? You've got your basic radiant cooling through the fitness of the metal. But, what other things are you doing to help increase or decrease a reflux in your head for various styles or desires of whisky- other products?
Chip TateWell, for instance on our direct fire stills, one thing that's kind of obvious with- I mean it's not that noble, but it's not as common, I suppose. We have infrared burner assembly that isn't just one burner, for instance, it's a number of burners and also it transmits a lot of the heat into this still via infrared heat is one of the problems you can have with direct fire or something like a power burner is that you've got really high velocity going through there, so the more you turn up the burner, the faster the gas is moving through the system, and the more you can end up heating up your flue pipe twice as fast as your heating up you still. But with this burner system, we can control different arrays at burners to give a lot more precision on overall heating level and also to make sure that our efficiencies are higher than you typically see in a direct fire system.
DJ for DalkitaHow are you monitoring that during operation?Are you looking at sensors or is this a look in there? What is their monitoring system on your flame look like for that system?
Chip TateWell, the way that system is set up is essentially manual in terms of how you actually correct, you could arbitrarily say zero to 100. For us, it would really be broken down to a minimum sort of firing point, and then there's a range inside of each burner assembly. For instance, we have burners to have afforded one turn down ratio, and most people know that means that they can efficiently operate down to a quarter of the nominal rating without getting all weird, and burning out, or burning dirty or whatever. But, we're able to take that to a higher, turn down rate by having multiple burner assemblies distributed under the still. So, the only regulation that goes into it has to do with safety stuff, so making sure, for instance, we have a hot pilot essentially for pushing gas in there. Then there are other sorts of safeties that link in- I kind of call him "Scram Protocol". So, basically, there are certain scenarios where you want to shut down the still, it doesn't like if there's a fire in the building, if the water cooling system stops working, or the power goes out, or any number of things that can mean a potentially unsafe condition. Our scram protocol, essentially, make sure that the condenser has plenty of water, and then the burner has no gas, so we stop. Stop making vapor and cool what you've got because that creates a stable shutdown scenario, and you don't have any runaway systems.
DJ for DalkitaIt makes perfect sense. With the cooling, what are you doing on the back-end of your skills? Are you doing anything like Thumpers? What are you doing on the second half of your still process?
Chip TateWe just use shell and tube condensers. Pretty standard stuff there, mine tend to be longer. I like that long cool down that you get to give more hot copper contact. That's probably the only functional difference in terms of how it performs on the spirit. There are other little things that we do, I used double tube sheets, the distiller turns still makers saying I just, I don't like the idea of cooling water leaking in my spirit at all ever. I don't know if you're familiar with the double tube sheets scenario, but the idea is that each end, rather than having a single tube sheet that provides the barrier between the water box and the shell, you have two tube sheets and they're separated by a gap. So if there's any leaking, for instance, around the tube seal and the water box, it leaks into the void and not under the shell and vice versa for the shell side. So it provides a certain level of verification. Of course, eventually, all shell into condensers are going to blow a tube, but that's pretty binary. When the still isn't on and you turn the condenser water on and stuff starts flooding out of the spirit safe, you got a problem. You got a confirmation that you have an elite there, but that's true of all shell and tube heat exchangers. Eventually, you're going to have to cut tubes and replaced them with rolling new tubes, that's pretty standard and boilers or other types of similarly bill heat exchangers. But, you don't have a sort of slow leak of either city water or, in our case, we actually use a re-circulation system to minimize our water usage. So, you've got something that'll have bacterial inhibitors, you've just got stuff you don't want to mix with your whiskey in there.
DJ for DalkitaOut of curiosity, this is mainly for my own interest more so than our listeners. Have you ever looked at doing a second tube inside your tube and Shell? So, basically, you're creating a donut for the vapor to flow down, that way you can quadruple your copper contact and decrease your length considerably.
Chip TateAre you talking about doing- you say don't know that you're talking about like a YouTube configuration or what do you mean?
DJ for DalkitaBasically, you're creating an annual list, so you'd have a five chamber system- where the first and fifth chamber would have cold water flowing kind of up the middle. The second and fourth chamber would be your vapor and distillate path. And then, the first chamber would be your conventional exterior cold water on the outside of your tube. So, basically, you have an annular space that vapors going down, and you're tripling, or quadrupling your copper contact.
Chip TateYes. What we do is we do baffles. So, we may have 10 foot condenser, and every between four and eight inches, there's going to be a baffle on the shell side directing that vapor back and forth, in and out to maintain the degree of turbulence that you want to have and to maximize copper contact. But, that's just how we do that. We want to be a gradual cooling process too.
DJ for DalkitaThat the downside of the double wall as you can really pull some things down. Just to jump into something a little controversial, Howard, what is your opinion on line arm slope doesn't matter. When does it matter?
Chip TateTo me, they shouldn't be that much controversy because it's just physics. Here's what I mean, as long as you're pointing upward, gravity will tell you that anything that condenses from that point, we'll trickle down. So back toward the pot rather than to the condenser point being, if at the point in your system where things point down, you're essentially pre condensing. Because whatever it is, whatever the weather, all of the vapor or some of the vapors condense, it will all eventually be condensed in the condenser presumably. And so which portions of it get condensed first are as critical. Now, when a line arm is pointed upward, in other words, any condensation of vapors is coming back toward the pot, then you've got something different because if you run the still on a high reflux situation, you can create a lot of thermal gradient as you go up this still. And so you're selectively reduce stelling; the vapors that are trickling back down, whatever feature you have. That said, you put enough heat on that still, and it won't really much matter because you're just blasting things through, and the amount of cooling in the room or whatever it is that would provide that reflux becomes minuscule compared to the rest of the system. And then you just, stuff hits the condenser and condenses. But, if you want the potential for reflux in a pod still scenario, then you need surface area and you need to be upward angled, so that you can have things trickling back down toward hotter vapors to create that essentially an infinite number of distillations, although that- Now, we're talking in discrete math, but you know what I'm talking about, that you create some indiscreet amount of reflux that depends on the setup, depends on the room, depends on the burner system, etc. But nonetheless, you're going to be more selectively taking things off the still and at a higher proof than if you were just collecting the vapor right off the boiling liquid surface.
DJ for DalkitaI guess the controversy I've read is, at what point does the line matter if it's so short that there's not enough time to create any interior reflux, then it's angled doesn't matter, and you need to achieve either a surface area volume or a length requirement, which is the same thing in order to create any reflux in your lineup.
Speaker 3Right. What I would say is, it's like sticking your hand out the window and asking if it causes drag. Well, how far did you stick it out? How fast are you going and how big is your hand? It depends on those things. There's always going to be some effect, but I guess what I'm really saying is, it's one of a number of different things, then they're going to create the potential for certain distilling effects. So it's important, but not just on its own. So having adequate burner control, having adequate air circulation in the room and having an overall still design where you can hold that level of reflux relatively stable. When you're trying to do that, all of those things are going to determine the effect of that particular liner. So, it's an important factor of several, I think that they kind of dictate how you can run a still.
DJ for DalkitaThat's actually where I've ended up on the issue as well. One last thing to talk about is "The Head." You're saying, you run a fairly simple head shape. Do you do any work on your stills with interchangeable heads where today I'm running a pot, tomorrow I can change out the fitting, and now I have a short column. Any kind of interchangeability like that?
Chip TateWell, we don't typically do that. We always do a flange between the pot and the neck. So in theory, that's always a possibility. That's mostly for pragmatic reasons in terms of moving a finished still into position or replacing parts by. That's not something that I tend to just design stills or a collection of stills that do what I want, because I guess this in part depends on the size of your still. So, our wash stills, for instance, for about 2,500 gallons.
DJ for DalkitaI understand what you're talking about. All those small stills out though.
Chip TateWell, what I'm saying is if you have a small still, then it's a lot more. If two guys can safely lift the head off and put a new head on, that's one thing. Now, it's not my particular thing that I like to do a lot. The first thing that we come to mind is to say, "Okay, if you do that, do make sure that you're constantly checking gaskets and that the people who are attaching bolts and such know about torque wrenches and make sure you don't break it, trying to fix it, cause that happens more than you think. But, our next stills are a little bit larger, so that makes it a little less practical to remove 3000 pound head, to bring the overhead crane, it's a rigging company kind of affair. But also I tried to just design stills that have the flexibility that I want, I tend to design stills that angle upward and have fewer maybe elaborate curves in certain ways, but more elaborate line arms or next or things that kind of control the fluid dynamics. Because one of the interesting things about is, if you could see, again this is just fluid dynamics that if you can see inside, say a boiling ball or a typical like Cognac, alamic still what's going on in that head is going to look pretty different at different distillation rates. That means, if you're really dialed in on your distillation rate, it just gives you a lot of variability compared to longer straighter setups. Because, you're creating some turbulence, and how much turbulence, and how much it affects the spirit depends a lot with those kinds of heads.
DJ for DalkitaIs that, generally, what you're putting on your equipment right now, is either kind of an Olympic style or where you have an expansion chamber heading up?
Chip TateFor lack of a picture, hours look more Scottish, less than bowling ball or something. They tend to taper upward and not expand back out again, but then the way in which they do that exactly, and the line arm designs are often different and more elaborate, but the sort of general tapering that you would often see in Scottish and Irish stills, again, there are certainly exceptions with lantern shapes or boiling balls, but for those that don't have that, I think those are probably more cannon shape generally to what we're building.
DJ for DalkitaThat makes Sense. What are you doing for cleaning your stills? Are you looking at spray ball placement to ensure that you're removing any sulfur that might precipitate out? Or, how do you design that- the cleaning?
Chip TateWe're really careful about cleaning, especially in terms of not doing it when it's not necessary. We clean out stills with a hose, pretty much. Making sure that the site glass is clean because it's a cycle as being able to see through it. Obviously, the heating services need to be clean and that doesn't necessarily mean shiny copper, although that's usually what you're looking at because of the acid in the wash. If you're talking a direct fire scenario, first distillation has to be more careful about burning, but then the higher acid content is going to tend to clean the copper outside of any burning effects. I don't really find any need to clean stills, and part of that is because when people do use acids or cost x or whatever, that's really hard on copper.
Speaker 3I mean, it can be done occasionally, but I just don't like it. I mean, there have been a number of incidents connecting to copper, or kubrick metals being pitted or damaged by caustic solutions and causing safety situations. Soft metals and caustics just really, you can buffer those cleaning things to make it less damaging, but it's still damaging. And so, I'm just not a fan of CIP insight a still, obviously, other scenarios. Absolutely, Mash Tun, serial cooker, for minerals, anything else of course. But we stills, we wipe them on the outside with a wet rag and we spray them down with a hose on the inside, maybe use a scotch brite or something on the inside of a sight glass if necessary, but that's about it.
DJ for DalkitaWhat piece of equipment do you think is the most important to focus on when you're starting your distillery?
Chip TateAll of it. That's a hard question to answer from one standpoint. Money, practicality, safety, quality. From what standpoint?
DJ for DalkitaI'd go with pick one. If you are going to start a distillery, where would you focus your time and effort on selecting the exact right piece of equipment?
Chip TateWell, I will answer your question this way. I mean, I talk to a lot of people who want my help and advice starting a distillery. The first question I pursue and rarely get a good answer to is, what do you want to make? And they say, "Whiskey". I said, "Okay, what kind of whiskey?" And they said, "Well, we're thinking this. We're thinking. I was like, Oh, can I get enough? I need you to say, "Hey, I want to make a corn whiskey that's reminiscent of these brands, but has this asked for like, I need a flavor profile. What is it you want to make? And if it's more than one thing, fine, but what do you want to make? Because we can't figure out how we're going to make it until we figure out what it is we're going to make. And then you work backwards from there. S So, do you know if you're going to work with a bunch of bits and solids? Like, for us, you could say that multi to have two peanut exchangers a critical piece of equipment, it might be irrelevant for other people depending on what it is you want to try to still, I mean obviously picking your stills is really critical. I mean, having the right still is- there's any number of right answers, but there's even more wrong answers. So that's definitely, I think picking a flavor profile, and then stills around that, then you get down to sort of process aspects and you can answer all the other questions like, how much are we going to make? etc. But you really have to design around your product and I think that's one of the problems that people face is that they don't really know what they want to make.
DJ for DalkitaI agree completely. I get asked all the time, "Well, what's the best still?" "I don't know. What are you going to make with your still?"
Chip TateExactly.
DJ for DalkitaWhere do you see the industry going in the next 5 to 10 years?
Chip TateI think, there's going to be a level of maturity. I think, we're going to continue to see some expansion in terms of number of distillers, and we'll probably see news articles that say that the whole world is changed forever, and we'll never be the same. Five years later, we'll say that, read stories that say that craft distilling is dead and it'll be somewhere in between. I mean, there's going to be, there'll be some point at which the number of craft distillers starts declining, but I don't think that's going to be a bad sign necessarily for the industry. I mean, there are a lot of people getting into this based on the number of people that are getting into this that maybe shouldn't be and we're going to see more. We're going to see some consolidation, hopefully not mostly by purchasing all that's been the pattern in the fleet, but things will kind of settle down. And the most important thing, I think, would be that all the craft distilling is, some conversations are almost tired for us. Most people have never even heard of craft distilling yet. And that's an important thing to realize that like the heyday of craft distilling, like you can go to the grocery store and buy craft beer, probably 10 different kinds of craft beer. You can get that at the corner store. And that was not the case in 1985, and so the advent of, you know, most people even knowing that our movement exists, that's coming up soon and that's going to be kind of cool. And I think it's important will we make and how we present ourselves because we're not on the stage yet. I mean, we kind of are. Like, what main strain with the main strain population thinks craft distilling is, is still being shaped, I think to a large degree, because it isn't really out there yet. It hasn't been around long enough.
DJ for DalkitaIf you were going to start your distillery over or start a new distillery or another new distillery, what do you think is something that most people aren't focusing on that should be focused on?
Chip TateSo many things. We spent the last three years building the framework into which we're putting this distillery, whether they say it or not, I think a lot of people are kind of like, "What the hell takes three years?" Well, and in this, some of this may be particular to our distillery in terms of not only location but more size. We had to negotiate directly with utilities because we need a 12 inch waterline and the amount of power that we draw is actually going to change the induction of the overall power grid, and that has been accounted for with acid. I mean, there's like a different level of engineering that comes into it. I don't know if there's any one answer for most people, but certainly sending up the staff, the corporate structure, the financing and the space is a lot more important than most people realize that they try to kind of fix it after the fact and that's not always possible.
DJ for DalkitaCool. Well, thanks for your time today. I really appreciate you coming on.
Chip TateIt's my pleasure. Look forward to hearing more podcasts.
AutomatedToday's interview is brought to you by the team of architects and engineers at Dalkita. Dalkita has been serving the craft distilling industry for over 13 years, and committee to production facilities that work. Now, let's get back to the show.
Colleen MooreThanks again to Chip Tate for taking the time to talk with us today. Up Next, we've got our captive distilling student, D.J. and his monologue on the anatomy of a pot still.
DJ for DalkitaI got a couple of comments after our first episode that I focused way too much on column stills and I didn't talk enough about pot stills. And I'm right in the middle of doing a custom still design for a client who's got a great manufacturer, but doesn't necessarily know anything about what you need in still. So, I figured that was a great opportunity to take some of the calculations I'm already doing, bringing them to you, and show you what you need to do to design a still. In this case, a pot still. So, let's get started on this. I like to look at the still, particularly a pot still or any still, for that matter, as three components. We have our pot, which is where we're going to charge with our washer or low wines. We have our head, which can be the pot still head, a column on our column still. And what I think of is the head goes all the way through the gin basket or thumper if we have one.
And then the last component is, the condenser or whatever we're using for cooling. And so I'll kind of address the design of the three components. We'll go through it and see what you think.
DJ for DalkitaWith the pot. Basically, the way I design stills, I guess the first thing they talk about is material. So everything in contact with liquid should be stainless steel and everything in contact with the vapor should be copper. The reason I do this is that copper has, well obviously we've talked about the properties for working as a catalyst in changing the flavor of the spirit, so that's probably the best thing. But it also has great thermal properties. It's very conductive of heat. So this is terrible in your pot, because any heat you're putting into your pot, can then be radiated back through the edge. This is not terrible, I guess if you're direct fire. If you have a direct fired still, you do want your pot to be copper, you'll get more even heating that way, and you'll be able to bring that heat up from the fire up into your liquid better and more efficiently. If you have a properly designed firebox, you can get really efficient here. So if more people who are direct fire, then you do want to a copper pot or at least a copper bottom on your pot, we'll just leave it there. But if you are doing either a direct steam or you were doing a steam coil, anything that is heating the liquid directly or in your liquid, then you want to have stainless on the outside of your pot, so that you can keep all that heat in there. The vast majority of the stills I design are steam coils in the liquid, so I want to stainless exterior to try to keep as much heat in there as possible. Typically, the difference between stainless and copper, it's something on the order of five to six times, the thermal resistance depending on where you want to call it. So just having that stainless, we'll give you a little bit insulation. If you are using copper, honestly, even if you're using stainless, we should probably be insulating our pots. So a great way to do this is have a stainless main vessel, then have a row of insulation. Then outside of that, put a really thin layer of copper that we already goes, "Look at that pretty copper still!" And you're still being able to take all the energy that you put into your pot, and put it into your liquid, and get it going rather than having to radiate it out into the room, and then cool the room. So that's the material. In terms of thickness. If you are going direct fire, your material needs to be at least one and a half times thicker than it would be if you weren't direct fire. So if you were doing copper and say you had a 10 mil copper plate on the bottom, that would be okay. But if you are then going direct fire, you need to be at least 15 mil, 16 mil, somewhere in that range for thickness on that bottom plate. Now, that math doesn't work if you're going from copper to stainless, but gives you an idea. For really small stills, we're talking 316, a quarter inch, somewhere in that range for stainless. Thickness is something I like to use pressure vessel calculations for. So, generally, we're going to look up what the tensile strength is of the material, and three or four stainless or whatever. Then we're going to take roughly a third off of that to use as our ultimate strength we can get to, and then we're going to say, "Okay, this is not a pressure vessel". So maximum pressure and here's going to be 15 PSI at the top or wherever we're putting our pressure relief valve, then we're going to take the height of the liquid. So if you have a real tall, skinny pot, for some reason, not great for distillation, but let's say you're doing it and three or four or five feet tall in your pot, then you'll add about a half PSI per foot to get you down to what the pressure is going to be at the base of your pot. And then you can use that to figure out times the surface area of your pot divided by what the maximum pressure is, and figure out how thick does this need to be? It's not that complicated. It's maybe a minute or two of math, but we'd need to make sure we're looking at that. If for some reason you want to design a pressure vessel, please get a professional engineer to do the work. That's not something you need to have just your regular fabricator down the street slapping together. That being said, you shouldn't design pressure vessels. Anyhow, there's no reason to maintain pressure in a still it's terrible for your distillation. So that being said, if I designed 15 PSI, we would have a pressure relief valve set much lower than 15. But that way, we're making sure that the material is thick enough, that we won't have any issues. Talking about that, let's make sure we have a pressure relief valve on the steel body. If you aren't doing a pot still and you do have a column still, there's potential for liquid up in there to cause a vacuum. So you want to make sure you have both a vacuum brake on the pot body as well as on your column. That way, if there is any interference in there, you won't accidentally collapse your pot. But today, we're talking about pot stills, so you only need one and what's make sure we have a vacuum break at the highest point in the system that's open. Generally, that means, at the top of our line arm, we'll have our vacuum breaker. And then at the lowest point in the system and the air part of the system is where we're going to put our pressure relief valve. So that would be basically right above the liquid lake. I've found that for sizing your vacuum breakers, you want to look at the drain. So if you are planning on emptying your still in an hour after distillation, look at your gallons per minute from that, then use that to size your vacuum breaker. That's typically going to be a worst case scenario then just vapor cooling in the still. If you turn it off and walk away, although check it, you never know, it could be the other way around. Other things on the pot are the steam coil. So the steam coil goes back to our conversation a couple of episodes back about cooling. So we can use those same calculations that we did for cooling to figure out how much energy we need to put into the pot. Generally speaking, I like to use a one hour heat up to get from room temperature, call it 70 degrees, to distillation temperature 173. Basically, we're looking at 100 degree temperature increase in one hour. And so that works out really well for easy math. So if we have a 500 gallon still, that weighs roughly 800 pounds, and we need to take that 800 pounds of, we'll call it water, and increase at 100 degrees. So we're looking right around 80,000 BTUs an hour in order to make that jump. That's not that complicated. You'll see a lot of rules of thumb out there on the Internet from still manufacturers that say a one pound of steam per gallon and that works out within 5% or so of me calculating it that way. So either one you're going to be good enough for sizing and the boiler to run your system. Once you have that heat that you're putting into your still, we need to look at sizing your steam coil. A couple of different ways to look at sizing, it is material. If you were going to use stainless cause that's what most steam systems are based off of, then I typically recommend using a thicker metal. Typically, at least schedule 80. That way we can, if there is carbonic acid creation after the heat comes out of the steam, that coil will last longer and you won't have a coil failure that ruins your still. That being said, if you were really going to design it to be as perfect as possible, we would look at using copper in there for the steam coil. I am not going to get into design and copper steam lines, that is a complicated topic and you should hire somebody to do that. Dimensions, that's one last thing. So for me, I like to design as compact of pots as I can, which in a perfect world would mean spheres. In reality what I do is, I calculate this circle volume for my pot size, then turn that into a circle and then figure out what the cylinder height would be off of that. So generally speaking, my stills will be about as tall as they are widened dimer. That will give me the smallest surface on the outside insulate and we can focus on getting all the heat into the pot. The other way to look at it is, to increase the radius on your still as much as practical, decrease that height so that you can create the largest evaporation surface. This will enable you to move the largest amount of fluid through your still as fast as possible. This is really good for stripping stills and things that you want to blow through quickly. Tomato, tomato, you can pick one shape or the other, either way, just make sure you're insulating it and keeping all that heat in there. Once we get out of the pot, the last thing to talk about is the neck. So since our pod has been, in my opinion, made out of stainless, we need to have a gasket of some sort to separate it from the copper and the vapor portion. Copper and stainless will create a mild galvanic reaction, particularly if there's liquid across there and, basically, your copper will get eaten away and played out on your stainless, so this will shorten the length of time- a lifetime of your still. If you don't have a rubber barrier of some sort between them, so liked I said "Stainless pot", then I typically do a tri clover tight fitting, depending on still size, maybe a bolted fitting, and then we'll go up to the copper neck. This isn't perfect. In theory, you would like to have everything above your liquid leg is copper. So, like I was just saying, you're going to have your cylinder of liquid, and then you want some kind of conical top on there, to neck down to your neck. In a perfect world, as soon as you got off of that cylindrical base, you would switch over to copper. I haven't found a good way to do that and not create galvanic reactions in there, and you'll see it from most manufacturers. It'll either be all copper or all stainless. You won't see people swapping back and forth too often. So once you get into your head, there's a whole lot of debates, how the shape of the head affects it. Generally speaking, there's three kinds of properties that are going to rule all. One is the amount of copper. So the more surface area of copper you can pack into the head, the more reaction surface will have available for your spirit. I'm not talking about packing your still with Copper Mesh, although, obviously that works. I think that moves us more into a column still design and you'd have to look at it from theoretical plates and flow rates and that kind of thing. On a pot still, what it generally means is, we're going to try to do spheres and do weird expansion shapes, so that the spirit comes up, and then has a large area to boil into. This is where some of the diamonds or onions come in, and you can see all kinds of interesting shapes out there. I don't really have an opinion about what shape is best, it's just kind of a fact of life. The next thing that'll affect your still is, the ratios. I guess we'll do a little engineering here. The Joules Thomson effect is basically what makes refrigerators work. What that means is that when a saturated liquid, nor for that matter, any vapor is neck down or throttled, it's temperature will then decrease. So when you go from your wide boil surface on your pot, down to a small neck, going through that neck, you'll have a rate increase in the vapor and that will cause the temperature to drop. This temperature dropping then can cause some of the liquid to come out and we'll see a lower, if it's steam, we'd call it "Quality". So this is good because we can then use this to create reflux in our pot still, and going from the wide pop body to a narrow neck to a wide body on your boil ball or your diamond or onion, whatever we want to call it down to another narrow neck. And then you'll see people stacking these things, and then we'll have another expansion chamber, and another contraction into the line arm. Each of those is, basically, guaranteed reflux point, particularly if properly designed. And so you can say, "Look, this still is going to have at least three points of reflux just from the Joules Thomson effect". I think it's important to look at. I don't necessarily know. If you want to stack multiple diamonds, at some point you just say, "Why don't you just get a plate? It's still". but it's something you need to look at when you're designing it; how much temperature do you drop? Do you want through those throttle points? How much do you want to drop out? If you throttle it too much, you can actually create a space where you've gotten basically all the reflux is occurring in that spot and you're going to to really crank on your temperature to force anything through it. I typically start looking at, so I have my BTUs coming into the still during heat up. I want 20% while I'm running it, so that's going to give me a volume of evaporation or at least at the start and I just use initial conditions, I don't model it all the way through. Now, I have my volume coming up, it's going to go through my throttle point. Let's say, I want a 10 degree Kelvin dropped to my throttle point, so that I get a 50% increase in quality. That's fairly simple math. We do all that and we create what our next sizes need to be. The last part of the head is, the surface area. So now that we're in copper, part of it's for the reaction, but the other part is, like I said earlier, it's very thermally efficient. So what that means is as your vapors rising through the head, it's giving off heat into the room. This is one reasons amongst many that you want copper up here. So by giving away its heat, therefore it causes reflux. That's why you can see, say the nice swan necks over in Scotland, they don't have any expansion points, they don't have a lot of that stuff. They just have big long lengths of copper, that will just cause reflux naturally as heat is given off, it works great. So how much heat is given off is a function of the area of the head. So if you look at the onion shapes on your cognac stills, they do have an expansion point in the neck, but then they just go out into this huge ball that is somewhere in the neighborhood of a third to 50% of the size of the pot body. And what that does is, it creates this huge area for heat to vapor off on. And so as this heat's coming off, it's blowing into the room and you're going to get a lot of reflux that way. So, those are the three main things to look at when you're designing your head shape is, how much reflux do you want to cause? How do you want to cause that reflux? And then use that to design what shape you're looking for. This is where you really get to play as a designer. Coming off of there, we're going to move into our gin basket or a thumper or not. If you're going to be using a thumper, typically first of all, make sure that you're not creating too much back pressure on your still. The liquid leg in your thumper is going to create back pressure. So first of all, make sure we not only have a vacuum break at a pressure relief behind that, but we have one on the other side as well just in case anything weird goes on in there. There's a whole lot of science going on with Thumpers because you're going to charge it without alcohol vapor, and then you're going to increase the temperature and the thumper. You're basically creating an additional leg of reflux and depending what you charge it at. So if you charge your Thumper with NGS, then it's going to have a huge amount of alcohol that'll start boiling off almost immediately. But if you do a 10% charge, you're charging it with the same as your wash. That temperature's got to really increase a long way from all this other steam and that vapor then will cause some of the flavor characteristics to come off of that pot. I've never really played much with numbers. I know the basic math around. I've designed a couple. I'm sure some of you know a lot about them, shoot me an email, let me know in the comments, which you think about Thumper design. How do you design your Thumper? They get pretty interesting. With Gin baskets, there's a couple of different ways to do them. One is in the column or the head. The other one is off on the line arm side. I vastly prefer doing it in the Carter head or line armed style, that way we can control where the oil goes. If you put it in your column or in your pot, all that oil is just going to drop straight down into your pot and you've got to clean it up later. If you have it over on the Carter's side, you can run that drain pipe back into your pot body if you'd like. I typically don't, I run it just to a drip leg and on a valve with a sight glass, so you can ensure there's some liquid staying in your leg, and you just open it and you can drain that oil into a separate pot. The nice thing there is, you can then control throwing out the oil, putting it in into your spirit, you can decide how much, you can use it for bidders. It just gives you a lot of control for, basically, no cost and it makes the cleaning a whole lot easier. A couple things to note. If you are developing a liquid leg in your Carter head, then now you have a Thumper, so you can get a proof increase, you can also create pressure buildup. So safety is a huge thing with these things and make sure we're designing them appropriately. Next part of designing your Gin head basket, however we're looking at it, is to ensure that the vapor flow through the basket is consistent. We need to try them first of all, get some kind of laminar flow through the cylinder, that way we're getting an equal amount of vapor into every single part. And, we need to ensure that we're not bypassing or missing an ingredients where then you have to put more in there to make up for the amount that's missing. It's not that hard. Basically, we're going back to where we were at the head of the pot and we know, generally speaking, what the flow rate is off of our still for a given temperature and input. You design what you want your temperature input range to be for your still and then say, "Okay, now we know this many cubic feet is going to be moving through the head every hour, every minute", then let's say we're doing copper, it's smooth wall sides with a nice well that's a ground down. Say, "Okay, and this is where we're looking for our friction factors and here's where we're at now we're in Laminar flow with this rate". Once you have that, then you just pick the right diameter and you're good to go. It's not that complicated math.
Line Arms. Everybody likes to talk about line arm angle. I don't think it matters for most of the distilleries out there. And the reason I don't think it matters is, the theory behind line arm angle is, that you will have some reflux in your line arm, and if that line arm was pointed up, the reflex will run back to your head and pot to be read is stilled. If it is down, it'll all run into the still. If it's flat, some runs each way. The reason I don't think it matters is, if you look at the number of BTUs lost per square foot of copper, it's large. Somewhere in the neighborhood of a thousand if I remember correctly, it's been five or six hours since I've looked at this. Anyhow, so that thousand BTUs, we're talking about putting something on the order of about 30,000 BTUs into your pot each hour during distillation for a small still, this is that little one on I'm telling you about. So if we're putting in 30,000 that means just to, and it cross back over across that line, back to a liquid, to create that reflux, we need to remove about 30,000. So roughly speaking, that means we need 30 square feet of copper in our line arm. If you have a one inch line arm, you have less than one inch of copper, which means you need something in the order of like a 300 foot line arm to create enough reflux to cause a heat loss to cause any reflux.
DJ for DalkitaNow let's start talking about a four inch line arm. Four inches turns into 16, turns into 40 ish square inches, which all of a sudden means we're getting roughly three feet per inch. I'll have it in my show notes. Don't worry about the math too much. So if we have three feet per inch, now we need a 10 foot line arm to get our 30. So unless you're running a 10 foot long, four inch line arm, you're not creating the reflux anyhow. And who's running a four inch line arm on a 200 gallon still? Now that being said, big stills, big line arms, long throws, this starts matters. It really is a big deal for the big scotch distilleries. But for somebody running a 500 gallon still that has a 10 foot line arm, it's not worth talking about. That being said, lots of people disagree with me, so there's that.
Colleen MooreAre you interested in filing a report with us? Well, we're actively seeking professionals to give us the lowdown on the technical aspects of distillery operations for our listeners. Contact us via our website with your pitch. Do you have feedback on this show? Well, send us an email to (distillingcraft@dalkita.com). Of course, if you want to find out more about this specific episode, go to our show notes on our webpage, that's: dalikta.com/shownotes. Remember, you can subscribe to this podcast at Apple podcasts, or however you get your podcast. Our theme music was composed by Jason Shaw, and is used under a Creative Commons attribution 3.0 license. And finally, a special thanks to the Dalkira team behind this production, and the man that puts it all together, our sound editor Daniel Phillips of Zero Crossing Productions. Until next time, stay safe out there- I'm Colleen Moore.
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