Help on Dual Element 120v controller

[beaugranbois]

I'm am looking for some help from the vast knowledge that is the members on this forum. I am looking to build my first element controller. I don't have a 220v plug in my garage so I was thinking about just building a 120v controller. I'll be running a standard insulated 15.5 stainless beer keg with two 2000w elements. Everything I've read leads me to believe that the 4000w will be enough to get the 13-14 gallon warmed up in just over an hour? I am currently building everything (boiler, still and controller) and hope to have the still up and ready to go by spring time. I have electrical experience but its been a long time and I never built something like this. Since I is my first controller build I've decided to be with potentiometers instead of PIDs. I've got or have coming just about everything I need to do the build, I think? So far I have a 10.25x7.25x3.75 control box, 2 pots with knobs & labels, 3 cord grips, 2 40amp SSR w/ heat sinks, a few terminal blocks, an emergency stop switch/main power switch, 2 ammeter/voltmeters, 3-4 temperature meters & plug sockets and a couple fans for cooling. I've also got a two switch set that I was wondering if I could use to switch the elements on and off. My first question is can I wire in these low amp switches between the pot and ssr to switch the elements on and off or would I need to get a higher amp switch like a house light switch to cut the power directly from the element? I've sourced around and haven't been able to find any schematic and very few 120v builds, no dual element 120v builds. If anyone could help me out with some advice, links to a similar build with schematics or have schematics for one like this. I would be greatly appreciative, so I don't do something wrong and burn up my garage. I have also seen breakers put into some, would I need to get one for this as well? I know I'm missing some questions but I'm trying the right this at work and am trying to make it quick. Thanks again everyone.

[Maritimer]

Hi beaugranbois,

Here is a post by sambedded, the controller guru: http://homedistiller.org/forum/viewtopi ... 85&t=51796 . He has another thread that has thousands of hits.

He shows a thermal switch to turn off the SSR in case of overheating, but you could put your low-amperage switch there to turn off the SSR. Further down the thread I added a flow switch with a bypass: http://homedistiller.org/forum/viewtopi ... 6#p7257521 .

If you're just starting the build, adding a jack for a flow switch is a good idea. The biggest common danger you can face in distilling is loss of coolant flow. Your shed will fill up with explosive ethanol vapour if you don't catch it.

M

[beaugranbois]

Thanks maritimer for the advice. I'll look into the flow switch with a bypass. I sure don't want to be blowing up my garage. I was planning on doing a nicer 220v controller down the line with PIDs and all the bell and whistles. And now that you say something about vapors that will definitely be in the plans for that.

[Massassi]

If you're running off of a regular 15a house circuit, I'd just use a standard 15a lightswitch. They're like 2 bucks at Rona and you know you won't melt them. Do t cheap out then dealing with electrical. Using something rated too low, can end up letting out the magic smoke - and after that none of it works. Then you have to rebuild and replace... Maybe even the garage.

[RedwoodHillBilly]

I did something similar initially. I had 2 20A GFCI protected circuits available. I used 2 phase angle controllers (dimmers on steriods). 1 each for each element. I didn't bother with power switches, just unplugged the controllers to shut them off. If you really want switches, there are toggle switches rated for 120V at 20A or you could just use common light switches. While flow switches as have been suggested are nice, it will add complexity. If you are present during the run as is prudent, you don't really need it. If there is a water flow problem, it will be readily apparent and you can take corrective action. If it was me, I would keep it simple and monitor the rig at all times. Don't run unattended.

[Snackson]

It seems like you're trying to make it too complicated. What I would do, buy two 12g extension cords, buy two small box Still Dragon DIY kits, some stainless 5500w elements (1376w@110), and an enclosure to hook up to your boiler and you're done. Very close to $100 total (depending on element guard, purchased would push cost up). No need for a flow switch as you should be sitting next to still the whole time. Cut extension cord where it's longer on the inlet to controller and your set. Technically, you only need one controller and can run the other full bore and adjust heat on one only. No need for all the bells and whistles. This is coming from a guy who has been E-brewing for over 6 years and has built multiple brewing panels. I use a SD kit for stillin' because it's easy and no nonsense.

[Maritimer]

Hi beaugranbois,

Don't listen to those guys telling you to forget the flow switch. That's equivalent to not using a seat belt, insisting that you are only going to drive carefully. In the real world, you will leave your still unattended or lose your attention. Distilling can get very boring and time-consuming. At least add the jack and a bypass switch now so that you can put in a flow switch after your first experience of smelling ethanol vapour in your garage.

M

[Snackson]

Hi beaugranbois,

Don't listen to those guys telling you to forget the flow switch. That's equivalent to not using a seat belt, insisting that you are only going to drive carefully. In the real world, you will leave your still unattended or lose your attention. Distilling can get very boring and time-consuming. At least add the jack and a bypass switch now so that you can put in a flow switch after your first experience of smelling ethanol vapour in your garage.

M

What about all those that run on their stove top? Do they need to go wire in a solenoid and flow switch to shut their stove down? Yes, it's a good safety switch and a nice to have, but not necessary. My ears work damn well and can hear the water trickling into my recirc tank. My eyes also work well and I can see if my product condenser is putting out liquid or vapor.

[beaugranbois]

I'm not looking to go fully automated but I would like to be able to walk away from the still. I've got two young boys and a third on the way, so safety and being about to keep an eye on them or tend to them if I need to is what I would like to be able to do. I do like the safety of it and I just looked on ebay and looks like they're not very expensive. I'll pay $10-20 and do a lil more wiring for that safety feature. I'm going to use most of the components when I get 220v wired into the garage and build a new more automated controller. Right now I'm just looking for a pretty basic dual controller. Well I guess to me it seems like a pretty basic controller. 2 pots, 2 ammeters, a master kill switch, and a couple thermo gauges for boiler, column and water output temps. I believe I might just be thinking that building a controller is harder than it really is. I guess I'm just looking for some basic schematics to check out and get the basic understanding down so I'm confident that I wont turn my control box into a puddle of bubbling plastic.

[Maritimer]

Hi beaugranbois,

If you are willing to have unequal element power, you can just put one element on an on/off SSR controlled with a low-current switch on the signal input. Use the pot to vary from 0 to max on the other element. The ammeter can go in series with both elements in parallel, so it will show the total current.

You aren't going to control boiler temperature, are you? It needs to boil.

M

[beaugranbois]

No, I just wanted to be able to keep an eye on what the boiler temp is doing. I drilled the port hole before really thinking and it might just end up getting plugged if I get no useful data from the boiler temp.

[Massassi]

the simplest of 110v systems would be a GFCI outlet powering a regular knob style dimmer switch for a living room. could probably all be built from parts you have lying around.

[RedwoodHillBilly]

Don't over think it. A pair of 2Kw elements don't really need controllers for a 15.5G keg. You could just plug them into separate circuits. If you calculate the vapor speed, you will find that this is right in the sweet spot. KISS theory applies.

[skow69]

I don't like to be contrary, but you can't calculate the vapor speed from the boiler size. You need the column dimensions.

[still_stirrin]

I don't like to be contrary, but you can't calculate the vapor speed from the boiler size. You need the column dimensions.

Homerun Skow.

Heat input in a vessel filled with a liquid mixture of various boiling points will produce a mass flow of vapor (determined by the composition of the mixture) proportional to the rate of transfer of heat into the liquid....that is, the heat input rate (not the scaler "temperature") determines the pounds per second of mass produced at saturation (lbm/s).

This mass flow has a temperature, a pressure and a resultant density. That mass flows into the piping network...cap and lyne, riser, or column and its rate establishes the feet per second of vapor velocity. As you can see, operating pressure affects it. But we distill at pressures very near to atmospheric, so the pressures should be (nearly) constant. Also, the rate of vapor production is related to the heat input (joules/second, or watts, or BTUs/second, etc.) and not the geometry of the vessel. (OK, so geometry does play into the flow characteristics..but that is, at best insignificant, and neglected in an engineering analysis. Things like pipe outlet shape, diameter of the vessel, and even the surface of the liquid/vapor interface can affect boil rates..but they are neglected as insignificant).

But keep in mind that flow in a piping network has pressure losses due to viscosity of the fluid (liquid or vapor) and as those losses occur, the pressure drops...which in the case of a vapor (compressible fluid) causes the vapor to expand...and since mass flow is constant, the vapor velocity increases. As it speeds, it's pressure continues to drop because of the friction losses and the speed continues to increase. This is what causes a "choked flow" in a vapor tube...that is, when the mass flow is limited due to sonic conditions in the tube. Only an increase in pressure at the source can increase the mass flow more. And we don't want the boiler to build up pressure because the flow is constricted in the vapor piping...right?

So, we try to keep the vapor speed (for the purposes of still design) at, or below 119 cm/sec (47 inch/sec) empirically:
"All these figures above equate to a vapor speed up the column of 119 cm/sec (47"/sec) Assuming for ease a column length of 119cm, that means that vapor will traverse the column in one second, and during that time it is busy condensing and being reboiled many times. "
(from the parent site: http://homedistiller.org/theory/refluxdesign/diameter" onclick="window.open(this.href);return false;" rel="nofollow).

Faster..and it will choke (potentially). Slower..and it will be inefficient..longer distillation duration and (potentially) lower product proof.

So obviously, column diameter is a key factor. And likewise, column length is also a factor to speed, and mass throughput (choked flow, remember).

That's the lesson in "Compressible Fluid Mechanics" for today. Next lesson...Thermodynamics 101: enthalpy, saturation temperatures, and latent heat of fusion.
ss

[RedwoodHillBilly]

I don't like to be contrary, but you can't calculate the vapor speed from the boiler size. You need the column dimensions.

Homerun Skow.

Heat input in a vessel filled with a liquid mixture of various boiling points will produce a mass flow of vapor (determined by the composition of the mixture) proportional to the rate of transfer of heat into the liquid....that is, the heat input rate (not the scaler "temperature") determines the pounds per second of mass produced at saturation (lbm/s).

Ya, physics is a bitch. Math is a bitch It isn't that hard. Thanks for the explanation, it might help someone.

edit: - reduced quoted text.

[skow69]

Help me out here, SS. I've seen you make this point before, and I would really like to understand it. Let me just hit the parts where I get lost.

But keep in mind that flow in a piping network has pressure losses due to viscosity of the fluid (liquid or vapor) and as those losses occur, the pressure drops

I'm not sure where viscosity comes in, but lets continue your example as a 2" packed column 47" long. We know that the pressure at the top of the column is atmosphere, 15 psi or 416 inches of water column (in.H2O), and the pressure at the bottom of the column is higher. The parent site page that you referenced quotes an article in Chemical Engineering that defines flooding as "pressure drop reaches 2 in.H2O per foot of packing" so our column can't have more than 8 in.H2O drop total, so let's say the pressure at the bottom of the column is 416 + 8 = 424 in.H2O.

.which in the case of a vapor (compressible fluid) causes the vapor to expand

From the ideal gas law PV=nrT, so PV (pressure times volume) at the column bottom must equal PV at the top. A 2" column has cross section of 3.14 sq.in. so volume is 3.14 cu.in. per linear inch of column. So PVbottom = 424 * 3.14 and PVtop = 416 * 3.20. So 3.14 cu.in. of vapor in the boiler expands to 3.20 cu.in. above the column.

and since mass flow is constant, the vapor velocity increases.

If vapor speed is 47 in./s. at the bottom, then the volumetric flow rate would be 3.14 * 47 = 148 cu.in./s. Volumetric flow rate at the top would be 3.20 * 47 = 150 cu.in./s. and vapor speed of 3.20 / 3.14 * 47 = 47.9 in./s. So vapor velocity of 47 in./s increases to 47.9 in./s.

Now here is where I have trouble.

As it speeds, it's pressure continues to drop because of the friction losses and the speed continues to increase.

What friction losses? And how does that reduce pressure?

This is what causes a "choked flow" in a vapor tube...that is, when the mass flow is limited due to sonic conditions in the tube.

What are sonic conditions?

Sorry for the hijack, beau. It got more involved than I thought. We could move this to another thread if you like.

[rad14701]

I am a firm believer in the KISS concept... YOU are the process controller... The fewer bells and whistles the better in my honest opinion... I'm a minimalist... Less crap to break and less crap to buy and less crap to maintain while getting the job done has worked for me for decades... I've dealt with folks that thought they were the big dogs on the block that got so wrapped up in the bleeding edge and one-upmanship to the point where it was obvious they had more money than brains...

Get your feet wet as simply and inexpensively as you can... If this hobby is truly for you, your next build can be incrementally more complicated and expensive... Don't over-engineer, over-think, or over-spend...

All that being said, running one element directly on one circuit and another using a cheapo controller on another would be a good starting point... That way you can have 2000W - 4000W with both elements plugged in and one regulated, 2000W unregulated, or 0 - 2000W regulated...

This hobby can be practiced safely and effectively on the cheap... Beyond that it's just a matter of how deep you want to dig into your pockets and how complicated you want things to be... As for me, I'll stick with KISS... YMMV...

[Maritimer]

There was an interesting program on CBC radio a couple of weeks ago--The 180--on which a professor was explaining that the safer a car was, the more risks the driver would take.

Rad, are you really dissuading readers from using safety devices because that would incline them to leave their stills unattended? As I said, in the real world, distilling is boring and time consuming and real people do leave their stills or stop paying attention.

So, is it more dangerous not to have safety devices and rely on the fear of danger, or is it more dangerous to have constantly-watching, never-bored safety devices monitoring and reacting to dangerous conditions and helping the user? Is putting on a safety belt so complicated that careful driving is preferable to using a simple contraption?

M

[Snackson]

Maritimer, I admire your stance on safety. I ask you this, have you ever seen an SSR fail? They fail closed, meaning full boil. Even with your fancy flow switch if the SSR fails, it's not going to shut it down. Find something to do next to your still and listen for the water flow, watch the drip/stream, and look/listen/feel everything going on with your still. I have a plan and have things to do around my garage while stilling so it's not too boring. I'm actually enjoy my time running my still.

[Maritimer]

Hi Snackson,

As a matter of fact, I have four SSRs ( four 1000W elements), each with a monitor to check that it is working. I do this by using zero-crossing SSRs. They turn on completely for 1/2 cycle, depending on whether or not the control voltage is high or low at the zero-crossing. Each half-cycle has an interrupt about 1/3 into the half-cycle, so the control voltage is set before the zero-crossing and then the actual element voltage is checked on the next half-cycle interrupt. The element voltage is monitored with an opto-coupler. I even have a hardware watchdog to check that my microcontroller is working. It controls a contactor, shutting off power if an SSR fails.

There is a description of my system here: http://www.artisan-distiller.net/phpBB3 ... =30&t=8686" onclick="window.open(this.href);return false;" rel="nofollow .

So, yes, I agree that a flow switch is only part of the safety solution. Maybe I should build and sell a controller with a flow switch input and SSR monitor. Or somebody else could do it, maybe on Still Dragon. Any entrepreneurs out there?

M

[rad14701]

There was an interesting program on CBC radio a couple of weeks ago--The 180--on which a professor was explaining that the safer a car was, the more risks the driver would take.

Rad, are you really dissuading readers from using safety devices because that would incline them to leave their stills unattended? As I said, in the real world, distilling is boring and time consuming and real people do leave their stills or stop paying attention.

So, is it more dangerous not to have safety devices and rely on the fear of danger, or is it more dangerous to have constantly-watching, never-bored safety devices monitoring and reacting to dangerous conditions and helping the user? Is putting on a safety belt so complicated that careful driving is preferable to using a simple contraption?

M

If you find this hobby boring in any way then perhaps it simply isn't the right hobby for you... This hobby is only as boring as you make it... There are many many more boring hobbies that I can readily think of... Using automation as an excuse to leave a still unattended is irresponsible, plain and simple...

This is a home based hobby for amusement and satisfaction, not an automated manufacturing plant that needs to run 24/7... Sometimes we shouldn't be dragging as many work concepts into the home... Leave them at the time clock... I know it can be tough for some members to grasp that, but that's how I see it as do many others... Probably overly tough for those in automation engineering careers that think they have to try to automate and/or improve absolutely everything... But I digress...

[Maritimer]

Hi rad,

Distillation as a science and a technology is anything but boring. It's the raw process of distillation that is boring, just as watching a dripping tap is boring. Do you think that only people who are fascinated by dripping taps are entitled to be distillers?

M

[rad14701]

Hi rad,

Distillation as a science and a technology is anything but boring. It's the raw process of distillation that is boring, just as watching a dripping tap is boring. Do you think that only people who are fascinated by dripping taps are entitled to be distillers?

M

I collect in streams, not drips... So there's your answer... But to expound upon that, I keep myself busy checking for leaks, collecting data, monitoring output and coolant rates, and whatever else needs done... Surely no time to be waltzing away from my still... If all I wanted was easy booze I'd head to any of the plethora of liquor stores within a few minutes drive...

Just pointing out that everybody doesn't need to start out fully automated, if ever... Distilling can be one of those hobbies where you need to keep your senses sharp, kinda like hunting, racing, and a multitude of others... If someone is into automation and just can't step away from it then I'd consider that somewhat unfortunate... But trying to promote automation simply as an easy way to make spirits does the hobby a certain amount of disservice... Might as well toss the idea to Keurig to make a machine that you pop a container of the flavor you want into the unit and eventually it produces the spirits you want while you go about your life without so much as a thought about what's going on with the overall process... Now that would be bliss, right...???

[Maritimer]

Hi rad,

As a matter of fact, my still is not yet automated. My mantra has always been that first a still must be safe before it can be automated. There hasn't been an incident ever, before and after adding safety devices, so this summer will see the completion of the automation project.

There isn't anything to record or watch on my VM still. I know its sweet spot and nothing changes once it's running, so I have to add safety features. Like many others, I make alcohol because it is cheaper than buying it. We would be consuming $10 per day otherwise, which on a retirement income is a lot of money.

Now as for bringing work home, don't forget about all the welders and machinists on this site who would never be reproached for bringing work home. I loved my work (which included machining), when I was working, and always brought home ideas to think about. But I have the impression that you hated your IT work (or was it programming?).

Anyway, all I am proposing is that every safety device helps, and I hope the OP will include at least a flow switch in his controller.

M

[raketemensch]

My career is based on automating with software, and it was the first thing I thought of when looking at this whole hobby/craft, and I've got raspberry pis and temp sensors and code to handle both, and the first thing I did was start looking at solenoid valves...

But then I started running my first, then second pot, and then built a flute, and realized that you can't really automate something that you don't really yet understand.

In the end I've come to enjoy running the still manually, so my first automation will probably be a step mash pot. But, again, until I understand how it all works, code and sensor hardware is somewhat moot.