Back shed Boka

[GroggyAl]

Here's a write up of my 2" BSB (Back Shed Boka if its not already in your acronym list). It was operational by Christmas and it produces a nice drop. Not sure if I will be adding the still building experience to my resume though. I won't go into all the boring construction details because there is already plenty of information on these forums but hopefully others can learn from my experience. So what is it? My BSB is the typical slant plate Boka with a Liebig product cooler which incorporates a parrot. I wanted it all compact so it didn't take up too much room and I made it so it could be dismantled into smaller components for storage. The reflux column is 1200mm long and packed with copper mesh and the boiler is the normal SS keg with a 2400 watt element. Cooling is done with a water recirculation system. I only have SS or copper in the distillate path.
If I had to do it again I would do it differently. I would buy a nice stainless steel FSD Boka top and just build the boiler and some of the accessories around it. Many thanks to Mac at FSD for advice along the way.

[GroggyAl]

The reflux condenser is the typical copper coil with a central cold finger. The 3/4" cold finger feeds 2 coils of 1m long 1/4 tube. I did it this way to maximise surface area for minimal pressure drop through system. The two 1/4 tubes come through a flat top plate and then join into a 1/2" outlet which makes it more robust. It seems to be very efficient and it knocked down boiling water steam at ease. The condenser has been wrapped in copper mesh but it still fits loosely in the top of the column.

[GroggyAl]

The top section has a clamp connection just below the bottom slant plate so I could easily dismantle it all and swap the packed column for a short open column for pot runs. The clamps are cheap and flanges are simple to make using rings made from 1/4 tube. I was concerned about keeping the ends square so I made a former out of a piece of 2" pipe split in half and clamped in vice that held the 2" copper. I machined an internal radius to the pipe before splitting. Now I can form the ends of the 2" copper pipe for the flange quickly and be confident they will be square. Work the copper around the internal radius of the former then loosen the vice to move the former further back and do it all again. Remove the former, slide the ring in place, solder then hammer flat.

[GroggyAl]

I decided to use recirculated water rather than town water going to waste. Not having the luxury of big water tanks or the real-estate for a 1000L IBC, I elected to go for a more compact closed circuit cooling system made from an old air conditioning unit. The old AC condenser & fan can be picked up from the scrap yards or any AC service companies. I borrowed a 12v pressure pump mounted on a plastic tank from my son just to test the system. It flows up 4.7L/min which is more than adequate. I will eventually mount one of these pumps inside the old AC unit with a small 10l holding tank so that it is all neat and compact. It will be inconspicuous when finally mounted on the back wall of the shed.

[Meatheadinc]

Nice work.
May i suggest you insulate the top of the boiler keg too, only suggested as you have gone to the trouble of insulating the rest and i have recently found large power savings using excessive insulation on my set up.

Air con systems are great. Most contain miltiple radiators that you can run separate feeds on for added efficiency. ( although not necessary )

[GroggyAl]

I followed others and mounted a Liebig downstream of the 3/8 needle valve. I thought about handling hot distillate cuts, unstable parrots or glass trial jars and decided I am too clumsy to go down that route. My parrot is mounted to the product cooler with its own drain valve. The Liebig is 1/2 copper inside 3/4" water jacket. To reduce the volume of the parrot and increase cooling I twisted up some strips of copper plate and installed it inside the cooler tube. The hot distillate has to run down the spiral (which is in contact with the inner tube) and stays in the bottom of the cooler until the parrot is full. It is very efficient and there is no surging effect on the alcometer. I drain the parrot/cooler regularly to minimise smearing.
I used a 1/2" cistern valve on the water outlet of the Liebig to control flow. Not sure if it is needed but the cistern valve is cheap, compact and controls water flow really well. It works a treat with continuous ABV monitoring of a cool product.

[GroggyAl]

The boiler is still work in progress. I welded an element fitting and guard in the side and found that to be harder than expected. I will have to do some more practice before I attempt to weld the 4" fill port in place. At the moment I fill and drain through the std 2" keg flange. I used the self-adhesive foam insulation with aluminium foil backing from Clark rubber retain heat and provide some personnel protection from burns. Once the keg is eventually complete I will insulate the top and bottom as well. A timber bench top will be incorporated so I have a secure bench for the collection jars.

[MacStill]

Lovely build Groggy, the penny finally dropped :laughing-rolling:

Welcome aboard mate :handgestures-thumbupleft:

[Andy]

nice mate. looks fantastic!

[GroggyAl]

I did a bit more work on my proposed self contained water cooling / recirculation system today. I have to give the 12v pump and tank that I used for my first couple of runs back to my son one day so I need to find a replacement. The 12v PD pump I think was perfectly sized (4.6 litres per minute at 60psi) however I would prefer 240v. It would just make for a neater installation with a single power supply.
I found a small plastic tank that will fit inside the old AC outdoor unit where the original compressor was mounted. It has a ball cock to maintain water level and a lid to keep sealed. Also from the scrap pile I found a 30w washing machine pump that could be mounted in the cabinet. After testing the pump today I don't feel confident that it will do the job. It can pump 8L/minute to 1.5m static head (open pipe) but by the time I run it through the radiator, RC and connecting pipe work it is down to 2 L/M with the extra friction losses. Despite having a NPSH of over 1.m it would not self prime without lowering the hose below suction head level. My cooling system will be mounted on the back wall of my shed so I can always raise it off the ground to overcome some head losses but my preference is to mount at ground level. Whilst it may be OK for my little Boka I don't want to rely on it for a new 4" bubbler in the future.
A 350w submersible pump from Bunnings will only just fit in my little tank but it seems a real overkill. I could not find a pump curve for the ozito but I found a simple head/flow curve for the similar 350w Commercial Electric barrel pump. The CE pump has twice the head but half the flow rate of the Ozito which may be better. There is no system or power curves to be found (if you could believe them anyway) but the specifications nominate a very low NPSH requirement in manual mode which should be ok in my small tank.
So this is where I need your help - has anyone measured how much current their 350w (1/2 HP) pump motor draws when throttled right back to very low flow rates? Being a centrifugal pump it should be lowest when throttled back (high pressure, low flow).
What is the minimum flow rate required for say a 4" bubbler RC.
For those using pond pumps, how does the flow of my washing machine pump compare (open flow)?
Any other recommendations / comments for a pump around 100 -150 watts (Submersible or dry mount)? My preference is the hardware store variety where I can rely on a warranty rather than go down the eBay route. I guess my fall back position is the 12v PD pump.

[Meatheadinc]

I use a 550w submersible with a couple of bypasses. It works great. I beleive over sized is good. Can prime any of my configuration from dry. I split the 4 radiators in my ac to allow bypasses and cooling. 1 pc 1 rc and 2 in parallel. I also fond that 12" pvc fits my pump and will fit in the houseing but havent fitted it
I suggest submersable over dry as less posiblity of leaks.
Good luck with it

[GroggyAl]

Hi Meathead.
Thanks for the advice and I will probably have to go down the bigger submersible pump route. Pity there isn't anything in-between at a reasonable price. It's a shame running a 1/2 horse motor for such a piddly arsed flow requirement. I'll defer the final decision on a pump until next year - it's all too hard :think:

So you cut out all the small bore tubing that combines the different flow paths in your AC cooler to effectively have 4 separate radiators? I was thinking about increasing that small bore tubing to reduce friction losses but there is very little flow going through the radiator after the still so the restriction should not be a problem. My AC unit was 7kw so I should have ample cooling capacity. Using one (or more) of the radiator flow paths for a pump bypass is an option (only really required with an oversized pump) but it's more plumbing and requires some form of flow control. It is already starting to get congested in my cabinet and once it is in its final position beside shed it won't be that accessible. The bypass may have to be external and go straight back into tank for simplicity. Interested to get your thoughts.

I put an amp meter on the old AC fan motor and draws just under 1/2 amp. That's approx 100 watts which I think is great for the cooling potential it has.
Will be interested to see what a 350w pump draws when the flow is throttled back. Hopefully someone has answers and I will be pleasantly surprised.

[Meatheadinc]

Yep i cut out and replaced the smaller tubes for higher flow and less restriction on the pump. This gives me plenty of scope for expansion to larger columns/boiler and more power if i choose to do so.

viewtopic.php?f=3&t=6973
My cooler can be seen in this thread although useing a wheelie bin as a resevouir at the time.

[GroggyAl]

Cheers MH, will keep working the options. I have another wash ready to go so will probably run washing machine pump to test (having the 12v one ready as backup).
Very impressive rig and control system you have. You obviously have too much spare time.

HNY

[GroggyAl]

Last year I was thinking about what pump to get. Today I just jumped in and did it. I bought a 350 watt submersible. I'd didn't go for the 350w Ozito though because that model only had 5m of head. I went for the CE (Commercial Electric) brand because it had 10m of head and lower flow rate.

I felt with my closed loop cooling system I need as much head as possible to overcome the extra friction head I have in my RC and radiator. Whilst my cooler will be relatively close to my still (just through shed wall), there will still be line losses through hoses and connectors. When it came to pump selection, head was more important to me - not flow rate. I would have had to go to the 750w Ozito to get 8m of head. More watts = more power consumption and more heat to be dissipated through the water.

I hope I have made the right decision???? To be on the safe side I have put a spare suction point on the bottom of my tank so I can easily retrofit a 12v PD pump if I am wrong. :shifty:

Initial tests show the 350w CE pump produces 12m of head which is better than expected but the open flow rate is lower than specified on the pump curve. Current draw is approx 1 amp when throttled back and flowing 4LPM through my entire system. It's drawing approx 1.15 amps at full open flow (no pressure just short hose straight back into tank). No where near as efficient as a 12v PD pump but at least it is not at the limit of motor capacity. I will play around with flow and bypass rates tomorrow to see if I can find a sweet spot.
Stay tuned.

[GroggyAl]

Ok here is the finished cooling water system all in one compact unit (an old AC split system cabinet). I completed a still run two nights ago with high ambient temperatures (26-29c) and it works brilliantly. The cooler keeps temperature of water well within 1.5c of ambient. I have a very small tank in the unit with a 350w Commercial Electric barrel pump from Bunnings. It produces over 11m of head which is heaps of capacity. Total cost for cooling system was just under $180 for pump, hose and fittings but most of the main components were salvaged from scrap heap.

The AC radiator has 5 flow paths. The original AC condenser configuration was 4 paths in parallel and then combining into the final 5th path (in series). I have re-plumbed it into two separate circuits - 4 paths in parallel for the main cooling and one path split off for cooling the bypass water. I bypass enough water to keep the system operating pressure at at approx 80kpa (8m head which I have extrapolated out to be the pumps BEP). The tank level is maintained from the mains supply through a float valve but it's only there in case the system springs a leak. The mains is also my backup if I had a major cooling system failure. The tank has a low level switch which will be interfaced with my future control system.

I monitor the supply and return temperatures at the Boka using an indoor/ outdoor digital thermometer mounted near the water inlet on the Liebig. The return temperature is taken from the water exit port of the RC. It's easy to adjust water flow based on exit temperature. The future control system will also monitor the temperature exiting the RC to trigger audible alarms set at circa 50c and full ESD at 60c. The Control Freak (Meatheadinc) has inspired me to do a full control system but that will be the subject of a separate post. :-D

The pump draws just over 1 amp and the fan just under 1/2 amp so 1.5 A in total. I couldn't get it much lower than this. 350 watts with 10+ metres head is a total over-kill. This unit will easily feed a much bigger still against higher head pressures. I am now on the look out for a smaller pump and cooler to see if I can make one simpler, more compact and get the power consumption down. I would rather put the power savings towards extra boiler heating.

Now the cooler is finished the current project is to 'pimp-out' the boiler. It now has 4 extra orifices that need to be closed up with more bling stuff. It's then time to build trolley / stand for the keg and control box.
I'll be rummaging through the surplus scrap heap if anyone is looking for me. :greetings-waveyellow:

[GroggyAl]

The boiler is done. An extra element, 4" clean/fill port, 1" drain connection and a spare 1" socket has now been welded in. Passed a hydro test at 100kpa and then a big clean up. Insulation was then stuck on top and bottom. Not sure what I am going to put in the spare 1" socket on the top - possibly a thermowell & thermometer but that would suff up plans I had for a bench top.

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[GroggyAl]

While on a roll with the tig torch I made up a SS trolley on casters. I need as much practice as I can get :)) Some more bling will be added once I figure how the control panel is going to be set up.

The drain connection comes out to the edge of the keg then turns 90 degrees so as not to cause a trip hazard. The valve outlet swings up out of the way when not in use.

Perfect timing as another wash is ready to go. :dance:

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[rumdidlydum]

Nice work there mate. I like your drain idea :handgestures-thumbupleft: just hope that step is stable with a boiler full i would hate to see it fall over :-B

[GroggyAl]

Rumi, the step is rock solid but I do need to make up the right thickness spacer (with a decent stop) to ensure levels are right. One thing I didn't consider is the door frame is lower than the rest of shed. My Boka just fits under it but suspect a 4" bubbler won't. ~x(
Means I will have to use a longer drain spout but it retracts nicely out of the way.